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2020-11-01 | Abstract The structural–morphological types and localization conditions of talc occurrences in the Beloretsk district of the Western Urals talc province are discussed. The talc mineralization is represented by low-iron talcites and talc stones in the Riphean clastic–carbonate complexes of the Bashkirian Meganticlinorium. Prospective talc objects in the Beloretsk district are classified as apocarbonate, to be distinguished from the apoultramafic deposits, which are predominant in the Urals. The hydrothermal–metasomatic genesis of the talc ores, their association with the metamorphosed dolomite-bearing members of the Lower and Middle Riphean Kyzyltash and Avzyan formations, the cooccurrence with magnesite deposits, and the absence of relationship with granitoid magmatism are established. The inner resources of the Riphean sedimentary basins, activated by metamorphic processes, are viewed as the sources of ore-forming fluids. The flanks of magnesite bodies in dolomite sequences near contacts with silicate interbeds are considered as the lithological settings favorable for talcite formation. The presence of the stacks of interbedded magnesian–carbonate and aluminosilicate rocks in the Riphean sequences facilitates the silica–magnesium bimetasomatism but leads to the formation of predominantly lean talc–chlorite stone varieties. The morphological types of mineralization are represented by the stratiform bed-like talcite and talc stone bodies; the saddle-like and ribbon-like talcite bodies confined to monoclines and fold hinges and limbs; and the fault controlled steeply dipping linear bodies of rich talc ores. | Structural-Morphological Types and Localization Conditions of the Apocarbonate Talc Mineralization in the Beloretsk District of the Western Urals Province | 10.1134/S1075701520060021 |
2020-11-01 | In textile and fashion industry, it is common to combine laser treatment and pigment printing processes for creating special design and aesthetic effects. Other than aesthetic effects, comfort is also a concern to the customer. This paper examines comfort properties, in terms of low stress mechanical properties, of laser treated and pigment printed denim fabric. Tensile, shearing, bending, compression and surface properties were examined by Kawabata evaluation system for Fabric under standard procedure. It was noted that tensile, shearing, bending and compression properties of the denim fabric were affected by laser treatment and pigment printing. This influence could be caused by action of the laser during the treatment as laser can damage the fabric and yarn, and can also burn the fabric surface. The pigment used in printing forms a thin layer on fabric surface making the denim fabric more rigid and difficult to deform. Moreover, surface properties of denim fabric samples were not affected by laser treatment or pigment printing and nor was there any effect of the two combined treatments. The denim fabric samples became smoother and had an even surface. | Effect of laser treatment on pigment printing on denim fabric: low stress mechanical properties | 10.1007/s10570-020-03461-7 |
2020-11-01 | The low-frequency (terahertz) dynamics of condensed phase materials provide valuable insight into numerous bulk phenomena. However, the assignment and interpretation of experimental results require computational methods due to the complex mode types that depend on weak intermolecular forces. Solid-state density functional theory has been used in this regard with great success, yet the selection of specific computational parameters, namely the chosen basis set and density functional, has a profound influence on the accuracy of predicted spectra. In this work, the role of these two parameters is investigated in a series of organic molecular crystals, in order to assess the ability of various methods to reproduce intermolecular forces, and subsequently experimental terahertz spectra. Specifically, naphthalene, oxalic acid, and thymine were chosen based on the varied intermolecular interactions present in each material. The results highlight that unconstrained geometry optimizations can be used as an initial proxy for the accuracy of interatomic forces, with errors in the calculated geometries indicative of subsequent errors in the calculated low-frequency vibrational spectra, providing a powerful metric for the validation of theoretical results. Finally, the origins of the observed shortcomings are analyzed, providing a basic framework for further studies on related materials. | Assessing the Performance of Density Functional Theory Methods on the Prediction of Low-Frequency Vibrational Spectra | 10.1007/s10762-020-00700-7 |
2020-11-01 | The trifluoroacetate metal-organic deposition (TFA-MOD) is one of the most appealing routes for the growth of high-quality YBa 2 Cu 3 O 7-δ (YBCO) coated conductors (CCs) due to its advantages of low cost and high efficiency. However, the puzzle of the inhomogeneities in microstructures and superconducting properties of YBCO CCs prepared based on the TFA-MOD route remain still a challenge. In this paper, 10 cm long YBCO films were prepared under different low-pressure conditions. These YBCO films were deposited on buffered Hastelloy C276 tapes using a dip coater. The effect of different ambient pressures on the microstructure and critical current density of YBCO films was investigated. High critical current density ( J C ) YBCO coated conductors with good homogeneity were obtained. The J C values (77 K, self-field) at different positions along the length direction of YBCO coated conductor were around 3.5–4 MA/cm 2 . The results showed that only under a suitable pressure the homogeneities of the microstructure and critical current density along the length direction of coated conductor can be greatly improved. The improvement was mainly ascribed to good texture and the absence of impurity phases BaF 2 and Ba 4 Y 2 O 7 in the films. (1) Solution-deposited long YBa 2 Cu 3 O 7-δ CCs with high homogeneity were obtained. (2) Excess water vapor causes formation of Ba 4 Y 2 O 7 in the YBCO films. (3) Excess water vapor converts orientations of needle-shaped grains from order to disorder. | High homogeneity 10 cm long BaTiO3-doped YBa2Cu3O7-δ films by the trifluoroacetate metal-organic deposition process | 10.1007/s10971-020-05367-z |
2020-11-01 | Abstract The results of studying the effect of microcrystalline complex alloys with alkaline earth metals (AEM) on the quality indicators of 17G1S-U pipe steel have been considered. It has been shown that the treatment of steel with these alloys reduces both the maximum score of non-metallic inclusions (NI) and the mean level of contavmination for the main types of inclusions including corrosive-active ones (CANI). Alongside with this, fine calcium, strontium and barium oxysulfides with a reduced oxygen content are formed in the metal. The complex alloys with alkali-earth metals contribute to obtaining a more homogeneous and refined metal structure, an increase in the cold resistance and corrosion resistance of steel. | Industrial Tests of Microcrystalline Complex Alkaline Earth Metal Alloys when Casting Pipe Steel | 10.3103/S0967091220110030 |
2020-11-01 | The present study focused on the full valorization of the tomato by-product, also known as tomato pomace consisting mainly of tomato peels and tomato seeds, by recovering natural antioxidants and edible oil, and subsequently reutilizing the leftover solid residues for the production of low-cost biosorbent. The tomato peel extract recovered using ethanol as food-grade solvent contained high phenol and flavonoid contents (199.35 ± 0.35-mg gallic acid equivalents (GAE)/g and 102.10 ± 0.03-mg quercetin equivalent (QE)/g, respectively). Even its lower content of lycopene (3.67 ± 0.04 mg/100 g), tomato peel extract showed potent antioxidant activity and can be therefore used as natural antioxidants either for food or cosmetic applications. High nutritional quality edible oil (17.15%) was extracted from tomato seeds and showed richness in unsaturated fatty acids (74.62%), with linoleic acid being the most abundant polyunsaturated fatty acid (49.70%). After recovery of these valuable compounds, the extraction solid leftovers were used to produce low-cost biosorbent tested for dye removal. Results showed that the highest biosorption yields were increasingly attributed to the acidic, direct, anthraquinone, then reactive dyes. Overall, the obtained results strongly support the complete utilization of tomato pomace for the recovery of valuable compounds and the sequential production of low-cost biosorbent. | Towards sustainable management of tomato pomace through the recovery of valuable compounds and sequential production of low-cost biosorbent | 10.1007/s11356-020-09835-5 |
2020-11-01 | This work aimed at investigating the low-velocity impact (LVI) behavior of hybrid epoxy-based laminates reinforced with woven Kevlar and Basalt fabrics. Six types of stacking sequences including sandwich hybrid, intercalated hybrid and not hybrid were employed for fabricating the specimens. Herein, the main focus of the study was to investigate the effect of Kevlar-Basalt hybridization on the low-velocity impact behavior of specimens. The impact tests were conducted using a drop-weight impact device at different energy levels of 30, 40, and 60 J. The impact properties of laminates were compared in terms of peak force, energy absorption and damaged area. Moreover, the low-velocity impact properties of specimens were simulated using ABAQUS finite element software and the results were compared with the experimental data. From the obtained results, the hybrid composite with intercalated configuration exhibited superior impact resistance. | Hybrid Effects of Basalt and Kevlar Fibers on Low-velocity Impact Behavior of Epoxy-based Composites | 10.1007/s12221-020-1418-z |
2020-11-01 | The aero-engine blades are mostly thin-walled with complex structures, which are prone to flutter, deformation during processing. All these characteristics make it difficult to machine the blade qualified. In order to improve the precision and efficiency of blades machining, a self-adaptive clamp machining process method is proposed in this paper. Then a self-adaptive auxiliary fixture of low-melting-point alloy which have simple structures is firstly designed based on the self-adaptive clamp method. The blade machining experiments of the low-melting-point alloy auxiliary fixture are carried out. And the experimental results show that the self-adaptive clamp method can improve both precision and efficiency in blade machining. But the low-melting-point alloy auxiliary fixture is still cumbersome and danger to the operators. Therefore, through analyzing the deformation in blade machining, an improved self-adaptive auxiliary fixture which is safe, efficient, and easy operated is re-designed. | A self-adaptive auxiliary fixture for deformation control in blade machining | 10.1007/s00170-020-06171-3 |
2020-11-01 | Abstract This short report substantiates the advisability of developing a two-stage model for the emergence and development of a boiling crisis. One of the stages is the violation of the stability of the two-phase wall layer, and the other is the appearance and fusion of dry spots on the heating surface. The use of a two-stage (“temporary”) model makes it possible to combine both well-known approaches to crisis analysis—hydrodynamic and thermal—in a single logical system. In the first approach, the characteristics of the boiling crisis are characteristic of high pressures in a boiling liquid, while those in the second are for low pressures. | On the Expediency of Developing a Two-Stage Model of Boiling Crisis of a Liquid Wetting a Heating Surface | 10.1134/S0040601520110051 |
2020-11-01 | The immune system is exposed to extremely low doses of neutrons under different circumstances, such as through exposure to cosmic rays, nuclear accidents, and neutron therapy. Peripheral blood mononuclear cells (PBMCs) are the primary immune cells that exhibit selective immune responses. Changes in the functions of the protein components of PBMC can be induced by structural modifications of these proteins themselves. Herein, we have investigated the effect of low-dose fast neutrons on PBMC proteins at 0, 2, 4, and 8 days post-whole body irradiation. 64 Wistar rats were used in this study of which, 32 were exposed to fast neutrons at a total dose of 10 mGy ( 241 Am-Be, 0.2 mGy/h), and the other 32 were used as controls. Blood samples were drawn, and PBMCs were isolated from whole blood. Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy were used to estimate the changes in the proteins of PBMCs. An alkaline comet assay was performed to assess DNA damage. Hierarchical cluster analysis (HCA) and principal components analysis (PCA) were utilized to discriminate between irradiated and non-irradiated samples. FTIR and fluorescence spectra of the tested samples revealed alterations in the amides and tryptophan, and therefore protein structure at time intervals of 2 and 4 days post-irradiation. No changes were recorded in samples tested at time intervals of 0 and 8 days post-irradiation. The FTIR band intensities of the PBMC proteins of the irradiated samples decreased slightly and were statistically significant. Curve fitting of the amide I band in the FTIR spectra showed changes in the secondary structure of the proteins. At 2 days post-irradiation, fluorescence spectra of the tested samples revealed decreases in the band tryptophan. The comet assay revealed low levels of DNA damage. In conclusion, low-dose fast neutrons can affect the proteins of PBMC. | Effect of low-dose fast neutrons on the protein components of peripheral blood mononuclear cells of whole-body irradiated Wistar rats | 10.1007/s11356-020-10085-8 |
2020-11-01 | We develop a new multiscale model to compute effective properties such as relative permeability, contact angle and partition coefficients in low salinity enhanced oil recovery processes for two-phase flow in sandstones containing reactive surfaces of kaolinite clay. In this setting, we construct a three-scale approach which entails the local nanoscale description ruled by the electro-chemistry of a confined electrolyte solution containing Na + , $$Ca^{2+}$$ C a 2 + , $$H^+$$ H + , $$Cl^-$$ C l - and $$OH^-$$ O H - ions residing between bounded crude-oil droplets at residual saturation and clay substrate. Our analysis focuses on the case of surface complexation geochemical reactions between the ionic species of the invading water and the electrically charged kaolinite and oil–water interfaces. In this scenario, we construct a local electric double layer problem for the electric potential based on a non-symmetric Poisson–Boltzmann equation supplemented by nonlinear boundary conditions with the magnitude of the surface charge strongly dictated by the geochemical reactions. By invoking the local mechanical equilibrium of the electrolyte solution and solving numerically the nonlinear problem using the finite element method, we compute the local ionic profiles and reconstruct numerically the disjoining pressure and adsorption isotherms for each ionic species for a wide range of brine compositions and pH of the water phase. Furthermore, combining the disjoining pressure results with the Frumkin/Derjaguin wetting theory allows to compute the dependence of the contact angle on wettability, pH and salinity. Subsequently, the formal homogenization procedure is adopted to upscale the pore-scale flow and ion transport to the macroscale giving rise to a new Darcy scale coupled flow/transport model. The hyperbolic part of the nonlinear homogenized model is solved analytically in an 1D example of enhanced oil recovery. | A New Multiscale Computational Model for Low Salinity Waterflooding in Clay Bearing Sandstones | 10.1007/s11242-020-01480-3 |
2020-11-01 | Abstract This article explores the possibility of enhancing the functionality of TKR7С-6 turbochargers by creating new friction pairs in bearing interfaces using ultrasolid ceramic coatings. According to the tests, the most efficient combination of materials for slider bearings is the friction pair including the ultrasolid B 4 C-BN coating and BrAZH9-4 bronze. Used in the TKR7С-6 turbocharger, this pair allows reducing the friction coefficient in bearing interfaces, which decreases the wear intensity as compared with the standard bearing assemblies in the turbocharger. A low friction coefficient positively affects the spinning dynamics of the turbo shaft and the ICE crankshaft. The test results can be used in engine building and maintenance production. | Modification of the Bearing Interfaces of a TKR7С-6 Turbocharger | 10.3103/S1052618820060047 |
2020-11-01 | MicroRNAs (miRNAs) have been reported to be correlated with various stress responses in soybean, but only a few miRNAs have been demonstrated to respond to low phosphorus (LP) stress. To unravel the response mechanisms of miRNAs to low-P stress, the roots of two representative soybean genotypes with different P efficiency, Nannong94-156 (a LP-tolerant genotype) and Bogao (a LP-sensitive genotype), were used for the construction of RNA sequencing (RNA-seq) libraries under low/normal-P treatment by high-throughput sequencing. In total, 603 existing miRNAs and 1699 novel miRNAs belonging to 248 and 1582 families in all samples were identified, respectively. Among these miRNAs, 777 miRNAs were differentially expressed (DE) across different P levels and genotypes. Furthermore, putative targets of DE miRNAs were predicted, and these miRNAs mainly targeted ERF (ethylene responsive factor), auxin response factors (ARF), zinc finger protein, MYB, and NAC domain transcription factors. Gene ontology (GO) analysis showed that targets of DE miRNAs were significantly enriched in binding, metabolic processes, biological regulation, response to stress, and phosphorus metabolic processes. In addition, the expression profiles of chosen P-responsive miRNAs and target genes were validated by quantitative real-time PCR (qRT-PCR). Our study focused on genome-wide miRNA identification in two representative soybean genotypes under low-P stress. Overall, the DE miRNAs across different P levels and genotypes and their putative target genes will provide useful information for further study of miRNAs mediating low-P response and facilitate improvements in soybean breeding. | Genome-wide identification of low phosphorus responsive microRNAs in two soybean genotypes by high-throughput sequencing | 10.1007/s10142-020-00754-9 |
2020-11-01 | Purpose Excess nutrients pose profound aquatic environmental impacts besides well-known essential elements for cropping. The enrichment of excess nutrients in riverine systems requires more investigation for various scenarios under different culture and governance regimes in the world. A survey on sedimentary nutrients (nitrogen and phosphorus) was conducted covering the lower Chao Phraya watershed in Thailand to explore their spatial and temporal patterns under various anthropogenic influences. Materials and methods Surface sediment and sediment core samples were collected from three subwatersheds (i.e., Pasak, Thachin, and Chao Phraya) of the lower Chao Phraya watershed in 2017. Various nutrient species (total nitrogen, ammonium nitrogen, nitrate nitrogen, total phosphorus, and phosphate phosphorus) were analyzed. The sediment cores were dated using a computerized multichannel gamma spectrometry. Multivariate statistical analyses were conducted to examine the spatial and temporal patterns of sedimentary nutrients, and to interpret their correlations with catchment land use pattern and socioeconomic development, respectively. Results and discussion Results identified spatial hot spot in downstream sections of Thachin and Chao Phraya subwatersheds and temporal hot moment between 1990 and 2000 for the three subwatersheds and an extra hot moment of 1960s for Chao Phraya subwatershed. Both spatial and temporal patterns of sedimentary nutrients were due to a shift from agriculture to urban land uses in the catchments. The catchment land use pattern explained approximate 33% spatial variation of sedimentary nutrient loadings with the top contributions of urban land use and water surface ratios in the studied watershed. With Thailand’s rapid industrialization, the nutrient sedimentation flux showed a temporal change in response to socioeconomic development with a turning point in the 1990s. Conclusions This study demonstrates that anthropogenic sources strongly influence sedimentary nutrient loadings following an order of urbanization > aquaculture > agriculture. Catchment land use pattern and socioeconomic development are efficient indicators to explain the variations of riverine environmental quality, both spatially and temporally. | Spatial and temporal variability of sedimentary nutrients in relation to regional development in the urbanizing lower Chao Phraya watersheds of Thailand | 10.1007/s11368-020-02739-4 |
2020-11-01 | Occupational exposure assessment is almost exclusively accomplished with personal sampling. However, personal sampling can be burdensome and suffers from low sample sizes, resulting in inadequately characterized workplace exposures. Sensor networks offer the opportunity to measure occupational hazards with a high degree of spatiotemporal resolution. Here, we demonstrate an approach to estimate personal exposure to respirable particulate matter (PM), carbon monoxide (CO), ozone (O 3 ), and noise using hazard data from a sensor network. We simulated stationary and mobile employees that work at the study site, a heavy-vehicle manufacturing facility. Network-derived exposure estimates compared favorably to measurements taken with a suite of personal direct-reading instruments (DRIs) deployed to mimic personal sampling but varied by hazard and type of employee. The root mean square error (RMSE) between network-derived exposure estimates and personal DRI measurements for mobile employees was 0.15 mg/m 3 , 1 ppm, 82 ppb, and 3 dBA for PM, CO, O 3 , and noise, respectively. Pearson correlation between network-derived exposure estimates and DRI measurements ranged from 0.39 (noise for mobile employees) to 0.75 (noise for stationary employees). Despite the error observed estimating personal exposure to occupational hazards it holds promise as an additional tool to be used with traditional personal sampling due to the ability to frequently and easily collect exposure information on many employees. | Estimating personal exposures from a multi-hazard sensor network | 10.1038/s41370-019-0146-1 |
2020-11-01 | An accurate numerical approach is presented for computing two-phase flows with surface tension at low-Mach regime. To develop such a model, where slight compressible effects are taken into account as well as correct thermodynamical closures, both the liquid and the gas are considered compressible and described by a precise compressible solver. A low-Mach correction has been implemented to eliminate excessive numerical dissipation. The interface between two-phase flows is captured by the level set method that is considered to be sharp. The interface capturing issue of the level set method within the Eulerian framework is the key point of the two-phase flow simulations, and in this work we propose a high-order coupled time-space approach for interface advection. Several numerical test-cases have been employed to validate the present numerical approach and enlighten its good performance. | An Accurate Sharp Interface Method for Two-Phase Compressible Flows at Low-Mach Regime | 10.1007/s10494-020-00125-1 |
2020-11-01 | Low molecular weight fucoidan (LMWF) extracted from Saccharina japonica exhibits many biological activities including immune regulation and inhibition of tumor angiogenesis, but little research has been done for its antioxidant effect in atherosclerosis (AS). In this study, AS modeling was successfully conducted in ApoE-/- mice by feeding atherogenic diet to animals. The antioxidant activity of LMWF was verified by determining its superoxide anion radical scavenging ability and hydroxyl radical scavenging ability. LMWF significantly increased the antioxidant capacity of AS mice, this conclusion being confirmed by total antioxidant capacity (T-AOC) assay. Test results confirmed that LMWF can enhance T-AOC by reducing reactive oxygen species (ROS) and oxidized low density lipoprotein (ox-LDL) levels and increasing glutathione peroxidase (GSH-Px) level in myocardium and liver tissues of AS mice. The results showed that LMWF and probucol had comparable antioxidant effects on AS, and when combined, no further antioxidant effect was achieved. | Low Molecular Weight Fucoidan from Saccharina Japonica Ameliorates the Antioxidant Capacity and Reduces Plaque Areas in Aorta in Apoe-Deficient Mice with Atherosclerosis | 10.1007/s11094-020-02278-9 |
2020-11-01 | Due to the fact that modern American and European women postpone childbirth until later in life, they are more likely to face the problem of ovarian insufficiency by the time they are ready to have children. So, the ability to restore the ovarian function safely is crucially important. Our study involved 38 women 31–45 years of age with low ovarian reserves and at least two unsuccessful attempts to receive their oocytes through IVF. The blood from the patients was collected into two BD vacutainers for PRP preparation. The platelet concentration in the PRP was 1 × 10 6 μl. PRP injections into the ovaries were performed by a gynecologist with a special 25G needle, 20 cm in length, as an ultrasound-guided procedure or a laparoscopic-assisted approach. After PRP treatment, women were tested with several criteria for 12 months. We saw a significant improvement in hormone levels; six healthy babies were born, ten pregnancies were achieved, and four out of the ten were from natural conception. The PRP injections into the ovaries are safe, productive, and a natural treatment that may help women with premature ovarian insufficiency to give birth to their own child. The difference and novelty with our method of ovarian rejuvenation is in obtaining a higher platelet concentration (about 1 × 10 6 μl), which allows us to achieve long-lasting results, within 12 months, after a single procedure. Additionally, for the first time, we proposed and successfully performed a laparoscopically assisted technique for administering PRP into the ovary. | Ovarian Rejuvenation Through Platelet-Rich Autologous Plasma (PRP)—a Chance to Have a Baby Without Donor Eggs, Improving the Life Quality of Women Suffering from Early Menopause Without Synthetic Hormonal Treatment | 10.1007/s43032-020-00266-8 |
2020-11-01 | Energy price is a key factor in reducing carbon emissions. This paper assesses the relationship between energy prices and carbon emissions from the industrial sector in China. Using panel data covering 31 industrial sectors for the period 2003 to 2015, we calculate the industrial energy price index and then estimate the effects of sector-level energy prices on carbon emissions based on a panel smooth transition regression model. The results show that the nexus between industrial energy prices and carbon emissions is nonlinear overall, and energy prices have a significantly negative effect on carbon emissions, while this negative effect gradually weakens with an increase in energy prices. Moreover, the negative effect of energy prices on carbon emissions is more significant in energy-intensive sectors when energy prices exceed the threshold value. The findings emphasize the importance of energy prices for energy conservation and emission reduction and imply that energy prices can be used as a regulation tool for government industrial energy saving and emission reduction. | Asymmetric effects of industrial energy prices on carbon productivity | 10.1007/s11356-020-10204-5 |
2020-11-01 | Aims We tested whether arbuscular mycorrhizal fungal (AMF) community might shift as host plant generations advance under a low phosphorus (P) soil. Methods Two greenhouse experiments were conducted using Medicago truncatula as the host plant, six AMF species, and two soil P levels. Experiment 1 assessed changes in AMF composition in roots and soil during five generations of host plant grown in low-P (5.7 mg kg −1 ) and high-P soil (24.0 mg kg −1 ). Experiment 2 tested the effects of single AMF species on host plant growth in low-P and high-P soil. Results Experiment 1 showed that AMF species composition at the OTU level in roots and soil significantly changed as host generations advanced, and that the pattern of change differed in low-P vs. high-P soil. In low-P soil, the dominant OTU in both roots and soil shifted from OTU-50 ( Glomus tortuosum ) to OTU-49 ( Funneliformis geosporum ) as host generations advanced. In high-P soil, the AMF community in roots and soil was dominated by OTU-50 in first two generations but OTU-49 and OTU-50 were co-dominant in the last three generations. Experiment 2 showed that mycorrhizal dependency indices based on plant biomass and P content in plant biomass, and spore numbers were higher in host plants with F. geosporum than other AMF fungal treatments in low-P soil. Conclusion As the host M. truncatula grew in a low-P soil over five generations, AMF community in root and soil shifted to a composition with F. geosporum as dominant species who was effective in foraging for P. | Changes in the mycorrhizal fungal community in host roots over five host generations under low and high phosphorus conditions | 10.1007/s11104-020-04694-y |
2020-11-01 | Purpose The purpose of this study was to reveal whether a transanal tube (TAT) could act as an alternative to a diverting stoma (DS) after laparoscopic low anterior resection. Patients and Methods A total of 89 consecutive rectal cancer patients whose tumors were located within 15 cm from the anal verge who underwent laparoscopic low anterior resection without a DS at our institution between May 12, 2015 and August 31, 2019 were included. All patients received a postoperative Gastrografin enema study (GES) through a TAT between the 3rd and 10th postoperative day. We planned two study protocols. From May 12, 2015 to March 31, 2017, we conducted a second operation including a DS construction immediately when radiological anastomotic leakage (rAL) was detected (Group A, n=46). From April 1, 2017 to August 31, 2019, we continued TAT drainage even if rAL was detected and repeated the GES weekly until the rAL was healed (Group B, n=43). Results In Group A (n=46), 14 cases of rAL were included, 11 of which underwent stoma construction. The remaining 3 patients who refused stoma construction were treated conservatively. In Group B (n=43) rAL was encountered in 10, and 7 of these patients were treated successfully by TAT continuous drainage. The rate of DS in Group B (7.0%) was significantly lower than that in Group A (23.9%) (p=0.028). Conclusions A TAT could act as a DS to mitigate the symptoms of anastomotic leakage after laparoscopic low anterior resection. | The possibility of a transanal tube as an alternative to diverting stoma in terms of preventing severe postoperative anastomotic leakage after laparoscopic low anterior resection | 10.1007/s00384-020-03624-9 |
2020-11-01 | The resonance of thermal lags of solid fuel with heat transfer oscillations in a boundary layer flow is the primary cause of low-frequency instability initiation in hybrid rocket combustion. A detailed study of two cases was conducted experimentally to investigate how the boundary layer is disturbed and leads to low-frequency instability (LFI); combustion with swirl injection and combustion with the frequency jump. The fluctuating boundary layer was successfully captured by visualizing images and proper orthogonal decomposition analysis was performed. The results show that swirl injection with an appropriate intensity substantially reduces the amplitudes of high frequency p’, and no boundary layer perturbation is found in the spectral analysis of mode 2, and Rayleigh index amplifications disappear. While the frequency jump occurs, the coupling status between p’ and q’ became weakly positive and the driving force disturbing the upstream flow was not made. As a result, oscillatory heat transfer was difficult to occur. Therefore, the appearance of boundary layer perturbation is the necessary precondition for the initiation of the low-frequency instability. And the resonance with the thermal lag characteristic leads to the occurrence of LFI. | Low frequency instability and oscillating boundary layer in hybrid rocket combustion | 10.1007/s12206-020-1039-x |
2020-11-01 | Objectives We evaluated the effects of low-level laser therapy (LLLT) using an infrared laser (IRL) and a red laser (RL) on the pulp of molar teeth in rats after dental bleaching to assess inflammation, collagen fiber maturation, and tertiary dentin formation. Materials and methods Eighty Wistar rats ( Rattus norvegicus , albinus ) were randomly divided into eight groups with 10 hemimaxillae in each of the following: control; bleached (Ble, 35% hydrogen peroxide [H 2 O 2 ]); Ble-1IRL and Ble-1RL (one IRL [808 nm, 30 s, 3 J] or RL [660 nm, 15 s, 1.5 J] application immediately after H 2 O 2 ); Ble-3IRL and Ble-3RL (three [immediately, 24 h, and 48 h] IRL or RL applications after H 2 O 2 ); and 3IRL and 3RL (three IRL or RL applications without bleaching). The rats were euthanized after 2 and 30 days for histological evaluation of inflammation (hematoxylin-eosin) and maturation of collagen fibers (picrosirius red). Additionally, the dentin deposition in the specimens obtained at 30 days was quantified via microtomography of the pulp chamber volume. Statistical analyses were performed ( P < 0.05). Results Initially, severe damages to the pulp were observed in the Ble and Ble-1RL groups. Ble-1IRL and Ble-3RL groups showed lower inflammation. The bleached groups had a greater amount of mature collagen fibers than the control group. The Ble-3IRL group had a greater number of immature fibers than the Ble group. At 30 days, there was an absence of inflammation and equal proportion of mature and immature collagen fibers. All bleached groups showed a reduction in the volume of the pulp chamber. Conclusion Three consecutive applications of RL and one IRL application can minimize damage to the pulp of bleached teeth, whereas three IRL applications can minimize pulp fibrosis. However, LLLT did not prevent deposition of tertiary dentin. Clinical relevance This study describes LLLT protocols capable of minimizing inflammation and maturation of collagen fibers in pulp tissue after dental bleaching. However, the protocols proved insufficient for reducing the formation of tertiary dentin in bleached teeth. | Influence of low-level laser therapy on inflammation, collagen fiber maturation, and tertiary dentin deposition in the pulp of bleached teeth | 10.1007/s00784-020-03258-9 |
2020-11-01 | Abstract For the first time, mineralogical, structural, crystal-chemical and isotope-geochronological data were obtained for a glauconite sample from the Lower Riphean Ust-Il’ya Formation on the Magan River (western slope of the Anabar Massif, northern Siberia). It has been established that glauconite from the lenticular layer of friable glauconitite (glauconite grains ≥80%) contains two populations of mixed-layer crystals, in which mica layers (93%) alternate with either smectite-type (7%) or vermiculite-type layers (7%) with the short-range order factor R = 3. The ratio K Al = ( VI Al / ( VI Fe 3+ + VI Al) equal to 0.45 allows identifying the micaceous mineral as glauconite with the unit-cell parameter b = 9.065 Å and K 2 O content of 8.29%. Comparison of new data with the previously obtained mineralogical and crystal-chemical characteristics of Ust-Il’ya glauconites from the Kotuikan River section (2.5 km above the Il’ya River mouth), located 65 km south of the Magan River section, showed both similarities and differences. Analysis of the crystal-chemical heterogeneity of Kotuikan glauconite samples from rocks of different lithological types revealed peculiarities in the distribution of individual mica varieties composing the glauconite globules. Isotopic dating of glauconite from the Magan River section was performed in combination with simulation of the distribution of octahedral cations and comparison of the results obtained with Mössbauer and infrared (IR) spectroscopy data. Such an approach combined with the mineralogical and crystal-chemical analyses contributes to correct interpretation of the stratigraphic significance of isotope data. The results obtained provide grounds for the conclusion that isotopic dates of glauconite from the Magan section (1474 ± 21 Ma) coincides within the error limit with the earlier Rb–Sr and K–Ar dating of the Ust-Il’ya Formation (1485 ± 13 and 1459 ± 20 Ma, respectively) based on the glauconite in the Kotuikan section (Zaitseva et al., 2016). The former value marks the stage of early diagenesis of sediments and is suitable for estimating the age of this formation. | Structural and Crystal-Chemical Features and Rb–Sr Age of Globular Glauconite in the Ust-Il’ya Formation (Lower Riphean, Anabar Uplift) | 10.1134/S0024490220060103 |
2020-11-01 | Background There is substantial interest in using networks of lower-cost air quality sensors to characterize urban population exposure to fine particulate matter mass (PM 2.5 ). However, sensor uncertainty is a concern with these monitors. Objectives (1) Quantify the uncertainty of lower-cost PM 2.5 sensors; (2) Use the high spatiotemporal resolution of a lower-cost sensor network to quantify the contribution of different modifiable and non-modifiable factors to urban PM 2.5 . Methods A network of 64 lower-cost monitors was deployed across Pittsburgh, PA, USA. Measurement and sampling uncertainties were quantified by comparison to local reference monitors. Data were sorted by land-use characteristics, time of day, and wind direction. Results Careful calibration, temporal averaging, and reference site corrections reduced sensor uncertainty to 1 μg/m 3 , ~10% of typical long-term average PM 2.5 concentrations in Pittsburgh. Episodic and long-term enhancements to urban PM 2.5 due to a nearby large metallurgical coke manufacturing facility were 1.6 ± 0.36 μg/m 3 and 0.3 ± 0.2 μg/m 3 , respectively. Daytime land-use regression models identified restaurants as an important local contributor to urban PM 2.5 . PM 2.5 above EPA and WHO daily health standards was observed at several sites across the city. Significance With proper management, a large network of lower-cost sensors can identify statistically significant trends and factors in urban exposure. | Using a network of lower-cost monitors to identify the influence of modifiable factors driving spatial patterns in fine particulate matter concentrations in an urban environment | 10.1038/s41370-020-0255-x |
2020-11-01 | In the present paper, a method for choosing the parameters of a wing-surface waviness intended for use on small aircraft is introduced. We propose choosing the waviness geometry based on the parameters of the boundary layer for the given regime of the flow around the classical wing installed at zero angle of attack, α = 0°. We propose to check the result of the choice of the waviness parameters by the change of the flow structure in the boundary layer of the wing. For the properly chosen waviness, the continuous separation zone characteristic of the classical wing should transform into local separation zones. To substantiate and verify the proposed method, we investigate the flow around two wing models, one model being a wavy wing with a rigid surface and the other, a wavy wing with a varioform surface characterized by variable hump height. The study was carried out at wing-chord-based Reynolds numbers Re ranging from 0.35·10 5 to 1.410 5 at α = 0°. Using oil-film visualization, a transition of local separation zones into a continuous separation zone on the rigid-surface wing model with a decrease of Reynolds number implemented by decreasing the flow velocity was revealed. By measuring the velocity profile in the boundary layer on the varioform wing, the transformation of the continuous separation zone into local separation zones yet at a constant velocity with a change in waviness height has been also demonstrated. It is experimentally shown that the formation of local separation zones is observed provided that the waviness height f is one order of magnitude greater than the displacement thickness σ l in the boundary-layer pre-separation region, and the waviness coefficient K w is greater than unity. A distinct formation of local separation zones is revealed by oil-film visualization at K w = 2.8. | Formation of local separation zones on the wings with a rigid and varioform wavy surface | 10.1134/S0869864320060074 |
2020-11-01 | The experiment was conducted to evaluate the effect of breed, diet, and level of feed supplementation on growth performance, feed conversion ratio, and survivability of Sasso and Kuroiler chicken. The study was conducted in two separate phases, i.e., the starter phase (0–6 weeks of age) and grower phase (6–20 weeks of age). One thousand sixty–day-old Sasso and Kuroiler chicks were raised until 6 weeks under intensive management system with three dietary treatments. At the age of 6 weeks, a total of 960 birds (480 Sasso and 480 Kuroiler) were randomly selected from each treatment diet and assigned to four feed supplementation levels, i.e., 25%, 50%, 75%, and 100% with two replicates each having 20 birds. Beginning week 7, birds were allowed to semi-scavenge from 6:00 am in the morning to 6:00 pm in the evening with free access to open grass area of 1 bird/4 m 2 . Grower rations based on the three categories, i.e., commercial, medium-cost, and low-cost formulation, were fed from 7th to the 20th week of age. During 0 to 6 weeks of the growing phase, the breed and diet significantly ( p < 0.05) influenced 6-week live weight, live weight gain, and feed conversion ratio. Birds given commercial diet (D1) excelled in live weight, total live weight gains, and feed conversion ratio followed by medium-cost (D2) and low-cost (D3) diet respectively. During the 7th to 20th weeks of the growing phase, the breed, diet, and supplementation levels had a significant influence ( p < 0.05) on the live weight and weight gain at 20 weeks of age. Feed cost per kilogram gain increased with an increase in the level of supplementation. Days taken by birds to reach market weight (2 kg) with 100%, 75%, 50%, and 25% level of dietary supplementation were 16, 18, 20, and more than 20 weeks respectively. The survival rate for Sasso and Kuroiler was 99.80% and 97.13% respectively. It is concluded that appreciable growth performance can be attained for semi-scavenging Sasso and Kuroiler chickens when supplemented with medium- or low-cost diets at the level of 50 to 75% of their daily feed requirements. | Evaluation of growth performance of Sasso and Kuroiler chickens fed three diets at varying levels of supplementation under semi-intensive system of production in Tanzania | 10.1007/s11250-020-02363-x |
2020-11-01 | Abstract In 2016 and 2017, from April to July, bird individual nesting home ranges were regularly mapped along the permanent census route (2.8 km) in the low-mountain forests dominated by pine and birch. For each bird species, the nesting densities and average sizes of the bird individual nesting home range were estimated, and raster maps of spatial allocation (MSA) at the scale of the raster grid of 50 × 50 m were obtained. The degree of spatial conservatism (DSC) for each local population was inferred from the pairwise comparisons of the specific MSAs obtained at the same area (28 ha) in different years with the use of the Gamma rank correlation method. The statistical dependence of the population habitat area on DSC was demonstrated earlier (Cherenkov, 2017). The more habitat area is found within the trial plot, the less dependent (random) the individual spatial allocation within a population is observed in different years. Significant DSC estimates (p < 0.05) were obtained for 15 species, and their habitat areas and habitat saturation were found. The population status was inferred from the degree of habitat saturation. Average estimates of the degree of habitat saturation were close in migratory and nonmigratory species (49 and 45%, respectively). The Altai migratory birds wintering in Southeast Asia did not differ statistically in the degree of habitat saturation from those wintering in Southern Europe and North Africa. A comparison of avifauna status of the Altai and Baikal regions revealed substantial differences. In Altai the number of the most common migratory nesting species is almost twice as high, their average nesting density is four times higher, and habitat saturation is twice as high as in the birds of the Baikal region. The interregional differences in the degree of habitat saturation indicate that most of populations of the migratory species of the Baikal region are subject to twice as much intensive pressure of some factors limiting the population growth compared to the Altai populations. At the same time, there were no significant differences in the ecological population status of the nonmigratory species between these regions. Close estimates of the degree of habitat saturation in nonmigratory species in the Altai and Baikal regions support a suggestion that the integrate influence of factors limiting their population numbers is similar in both regions. Close estimates of the degree of habitat saturation and nesting density in the migratory and nonmigratory Altai species show that neither of the two strategies of surviving gives a pronounced advantage. The difference between the Altai and Baikal regions in the degree of habitat saturation in the migratory species is seemingly determined by the different mortality levels in the wintering areas and on the routes of migrations. | Ecological Population Status of the Most Common Bird Species in Northern Altai Low-Mountain Forests and the Principal Difference in Avifauna Status in Altai and Baikal Regions | 10.1134/S1995425520060062 |
2020-10-29 | Background The extraordinarily resistant bacterium Deinococcus radiodurans withstands harsh environmental conditions present in outer space. Deinococcus radiodurans was exposed for 1 year outside the International Space Station within Tanpopo orbital mission to investigate microbial survival and space travel. In addition, a ground-based simulation experiment with conditions, mirroring those from low Earth orbit, was performed. Methods We monitored Deinococcus radiodurans cells during early stage of recovery after low Earth orbit exposure using electron microscopy tools. Furthermore, proteomic, transcriptomic and metabolomic analyses were performed to identify molecular mechanisms responsible for the survival of Deinococcus radiodurans in low Earth orbit. Results D. radiodurans cells exposed to low Earth orbit conditions do not exhibit any morphological damage. However, an accumulation of numerous outer-membrane-associated vesicles was observed. On levels of proteins and transcripts, a multi-faceted response was detected to alleviate cell stress. The UvrABC endonuclease excision repair mechanism was triggered to cope with DNA damage. Defense against reactive oxygen species is mirrored by the increased abundance of catalases and is accompanied by the increased abundance of putrescine, which works as reactive oxygen species scavenging molecule. In addition, several proteins and mRNAs, responsible for regulatory and transporting functions showed increased abundances. The decrease in primary metabolites indicates alternations in the energy status, which is needed to repair damaged molecules. Conclusion Low Earth orbit induced molecular rearrangements trigger multiple components of metabolic stress response and regulatory networks in exposed microbial cells. Presented results show that the non-sporulating bacterium Deinococcus radiodurans survived long-term low Earth orbit exposure if wavelength below 200 nm are not present, which mirrors the UV spectrum of Mars, where CO 2 effectively provides a shield below 190 nm. These results should be considered in the context of planetary protection concerns and the development of new sterilization techniques for future space missions. Video Abstract | Molecular repertoire of Deinococcus radiodurans after 1 year of exposure outside the International Space Station within the Tanpopo mission | 10.1186/s40168-020-00927-5 |
2020-10-23 | Background Thermal control after birth is an essential part of neonatal care. However, the relationship between neonatal temperature at and after admission is unknown. This study aimed to evaluate the change between neonatal temperature at admission and at day 1, and its impact on mortality. Methods Retrospective observational study at the Beira Central Hospital, Mozambique. Axillary temperatures were recorded at admission and at day 1 in 1,226 neonates who were admitted to the Special Care Unit between January 1 and December 31, 2017. The relationship between mortality rate and temperature change was evaluated with a matrix plot and a forest plot (obtained from a logistic regression model as odds ratios with 95% confidence intervals). Results Normothermia was found in 415 neonates (33.8%) at admission and in 638 neonates (52.0%) at day 1. Mortality rate was highest in (i) neonates who remained in severe/moderate hypothermia (74%), (ii) neonates who rewarmed from hypothermia (40–55%), and (iii) neonates who chilled to severe/moderate hypothermia (38–43%). Multivariable analysis confirmed that temperature change from admission to day 1 was an independent predictor of mortality (p < 0.0001). Conclusions In a low-resource setting, one out of three neonates was found hypothermic at day 1 irrespectively of admission temperature. Relevant thermal deviations occurred in a high proportion of newborns with normothermia at admission. Being cold at admission and becoming cold or hyperthermic at day 1 were associated with increased likelihood of mortality. Appropriate actions to prevent both hypothermia and hyperthermia represent both a challenge and a priority during postnatal period. | Impact of temperature change from admission to day one on neonatal mortality in a low-resource setting | 10.1186/s12884-020-03343-7 |
2020-10-23 | Background External fixation is a mainstream limb reconstruction technique, most often used after a traumatic injury. Due to the high rates of trauma in developing countries, external fixation devices are often utilized for immediate fracture stabilization and soft tissue repair. Proper external fixation treatment too often still fails to be adopted in these regions due to the high cost and trauma complexity. A novel, inexpensive, unilateral fixator was constructed using 3D printed clamps and other readily available supporting components. ASTM standard F1541 tests were used to assess the biomechanical properties of this novel external fixator. Methods Applicable sections of ASTM standard F1541 were used to determine the biomechanical properties of the novel external fixator. 3D printed clamps modeled using SolidWorks and printed with chopped carbon fibers using a fuse deposition modeling (FDM) based 3D printer by Markforged (Boston, MA) were used. This study included 3 different testing configurations: axial compression, anterior-posterior (AP) bending, and medial-lateral (ML) bending. Using the novel unilateral fixator with 3D printed clamps previously sterilized by autoclave, an input load was applied at a rate of 20 N/s, starting at 0 N via a hydraulic MTS tester Model 359. Force and deformation data were collected at a sampling rate of 30 Hz. There was a load limit of 750 N, or until there was a maximum vertical deformation of 6 mm. Also, 4 key dimensions of the 3D printed clamps were measured pre and post autoclave: diameter, width, height and length. Results The novel external fixator had axial compression, AP and ML bending rigidities of 246.12 N/mm (σ = 8.87 N/mm), 35.98 N/mm (σ = 2.11 N/mm) and 39.60 N/mm (σ =2.60 N/mm), respectively. The 3D printed clamps shrunk unproportionally due to the autoclaving process, with the diameter, width, height and length dimensions shrinking by 2.6%, 0.2%, 1.7% and 0.3%, respectively. Conclusion Overall, the biomechanical properties of the novel fixator with 3D printed clamps assessed in this study were comparable to external fixators that are currently being used in clinical settings. While the biomechanics were comparable, the low cost and readily available components of this design meets the need for low cost external fixators in developing countries that current clinical options could not satisfy. However, further verification and validation routines to determine efficacy and safety must be conducted before this novel fixator can be clinically deployed. Also, the material composition allowed for the clamps to maintain the appropriate shape with minimal dimensional shrinkage that can be accounted for in clamp design. | Low cost 3D printed clamps for external fixator for developing countries: a biomechanical study | 10.1186/s41205-020-00084-3 |
2020-10-23 | The focus of this study was the experimental determination of surfactant adsorption during low salinity water injection combined with surfactant flooding (LSW-SF) into an oil reservoir and development of an analytical model to predict this adsorption. The experimental model used was surfactant adsorption on silica and aluminosilicate coated quartz crystal surfaces in a quartz crystal microbalance (QCM), taking into consideration different surfactant concentrations, different surfactants, and the effect of different oils. In a previous study, the authors developed a method for determining the oil desorption from surfaces in QCM measurements. In this method the frequency decrease due to surfactant adsorption was determined experimentally by carrying out the blank measurements, and the role of the oil in the surfactant adsorption process was neglected. Therefore, in the developed calculation procedure for simplicity and practicality, it was assumed that the surfactant adsorption is independent of the oil properties. The analytical solution of the developed theoretically model in this study and the associated QCM experiments with different oils showed that taking into account the role played by the oil, it was possible to predict the difference in surfactant adsorptions with different type of oils, and there is a good agreement between analytical and experimental results. The results of the model reveal that surfactant\oil replacement on silica surfaces increased with increasing concentration of surfactant on silica surfaces. On the other hand, it decreased on aluminosilicate crystals with increasing surfactant concentrations. | Modeling of surfactant adsorption on coated quartz crystal surfaces during surfactant flooding process | 10.1007/s42452-020-03714-x |
2020-10-23 | Typical green roof systems are used to improve downstream water quality and reduce long-term total runoff. However, they perform poorly at peak discharge reduction during large design storm events. This performance can be significantly improved by the addition of storage a layer (blue roof) underneath a green roof system. This paper presents a simple design methodology for designing modular green–blue roof systems to reduce this peak discharge. In particular, the methodology can be used for the preliminary design of the blue roof module’s outflow control sizing. It is then shown how the resulting design can be incorporated into a standard hydrologic modeling system for a more detailed analysis. Results of an example design show that the addition of just 3.8 cm (1.5 in) of storage can result in a 38.6% reduction in peak discharge for a rainfall depth of 17.2 cm (6.78 in) compared to a green roof without underlying storage. Increasing the storage depth to 7.6 cm (3 in) for the same storm resulted in a 78.2% reduction of peak discharge. | A simple method for sizing modular green–blue roof systems for design storm peak discharge reduction | 10.1007/s42452-020-03725-8 |
2020-10-22 | Background The purpose of this study was to observe the effect of hematoporphyrin monomethyl ether (HMME)-mediated low-frequency and low-intensity ultrasound on mature and stable Staphylococcus aureus ( S. aureus ) biofilms under different ultrasound parameters. Methods The biofilm was formed after 48-h culture with stable concentration of bacterial solution. Different types of ultrasound and time were applied to the biofilm, and the ultrasonic type and time of our experiments were determined when the biofilm was not damaged. The penetration effects of low-frequency and low-intensity ultrasound were decided by the amount of HMME that penetrated into the biofilm which was determined by fluorescence spectrometry. Results The destruction of biofilms by pulse waveform was the strongest. Sinusoidal low-frequency and low-intensity ultrasound can enhance the biofilm permeability. For a period of time after the ultrasound was applied, the biofilm permeability increased, however, changes faded away over time. Conclusions Low-frequency and low-intensity sinusoidal ultrasound significantly increased the permeability of the biofilms, which was positively correlated with the time and the intensity of ultrasound. Simultaneous action of ultrasound and HMME was the most effective way to increase the permeability of the biofilms. | The penetration effect of HMME-mediated low-frequency and low-intensity ultrasound against the Staphylococcus aureus bacterial biofilm | 10.1186/s40001-020-00452-z |
2020-10-22 | Background Simulation based learning (SBL) is a technique where teachers recreate “real life” clinical experiences for health care teams for purposes of gaining clinical skills in a safe environment. There is evidence that SBL is superior to the traditional clinical teaching methods for acquisition of clinical skills. Although it is well established in resource rich settings, there is limited experience in resource limited settings and there is uncertainty regarding how SBL will be perceived among the stakeholders in medical education. As part of the steps leading to implementation of a SBL program at a university in Uganda, we sought to describe the perceptions of various stakeholders regarding the introduction of SBL methodology into learning at a medical school in Uganda. Methods We conducted a formative qualitative assessment using key informant interviews (KIIs) among faculty members and university administrators and focus group discussions (FGDs) among medical and nursing students at Mbarara University of Science and Technology. Data were collected till saturation point and were transcribed and analyzed manually using open and axial coding approaches to develop themes. Results We conducted seven KIIs and three FGDs. Overall, findings were categorized into five broad themes: 1. Motivation to adopt simulation-based learning 2. Prior experience and understanding of simulation-based education 3. Outcomes arising from introduction of medical simulation 4. Drawbacks to establishment of medical simulation; and 5. Potential remedies to the drawbacks. Overall, our data show there was significant buy-in from the institution for SBL, stakeholders were optimistic about the prospects of having a new method of teaching, which they perceived as modern to complement the traditional methods. There was significant knowledge but very limited prior experience of medical simulation. Also, there was some concern regarding how students and faculty would embrace training on lifeless objects, the human resources needed and sustainability of simulation-based learning in the absence of external funding. Conclusion Stakeholders perceive SBL positively and are likely to embrace the learning methods. Concerns about human resource needs and sustainability need to be addressed to ensure acceptability. | Stakeholder perceptions about the establishment of medical simulation-based learning at a university in a low resource setting: a qualitative study in Uganda | 10.1186/s12909-020-02301-3 |
2020-10-21 | Nitrate contamination has gain significant research interest, since presence of nitrate in large quantity in drinking water, often causes health disorders. In present day situation, nitrate removal is important aspects of water treatment process. Prevailing process, conditional influence and various approaches play important role in nitrate remediation. Various physical and chemical methods are available to remove the nitrate from groundwater; these are effective in removal but expensive in operation. To overcome these limitations, low cost bench scale water system with suitable adsorption method is adopted. In the present study, a treatment system was developed for community level comprising of anoxic batch reactor; filtration unit and a chlorination unit. Adsorption method is extremely useful in nitrate removal for different dosages such as: 5 g/L, 7.5 g/L, 10 g/L, since it retains nitrogen within the root zone. From the experiment, it is found that, low cost bench scale treatment method was effective in nitrate removal as material used were cost effective and locally available. Adsorbent method such as fly ash shows prominent result compared to other adsorbent such as activated carbon for an optimized condition of 7.5 g/L. Hence it can be recommended compared to other methods. | Low cost bench scale community level water treatment system and adsorption method for removal of nitrate from groundwater | 10.1007/s40899-020-00465-w |
2020-10-20 | Background Very low birth weight (VLBW) infant thermal instability upon neonatal intensive care unit admission has been associated with respiratory morbidity; however, the association between ongoing thermal instability and respiratory morbidity remains unclear. Methods A longitudinal data analysis was conducted on 12 VLBW infants. Chronic respiratory morbidity risk was defined as supplemental oxygen requirement (FiO 2 ) or scheduled diuretic dosing at 36 weeks post-menstrual age. Acute respiratory morbidity was quantified as desaturations (SpO 2 <90%), bradycardia with desaturations (HR<100 and SpO 2 <90%), apnea, increase in FiO 2 requirement, or increase in respiratory support. Multi-level, mixed-effects models and regression analysis examined the relationships between body temperature over the first 14 days of life and respiratory morbidities. Results Body temperature was not associated with chronic respiratory morbidity risk ( p= 0.2765). Desaturations, bradycardia with desaturations, increased FiO 2 requirement, and increased respiratory support were associated with decreased body temperature ( p< 0.05). Apnea was associated with increased body temperature ( p <0.05). The covariate-adjusted risk of desaturations ( aOR =1.3), bradycardia with desaturations ( aOR =2.2), increase in FiO 2 requirement (aOR =1.2), and increase in respiratory support ( aOR= 1.2) were significantly greater during episodes of hypothermia. Conclusion VLBW infants are dependent on a neutral thermal environment for optimal growth and development. Therefore, the significant associations between hypothermia and symptoms of acute respiratory morbidity require further study to delineate if these are causal relationships that could be attenuated with clinical practice changes, or if these are concurrent symptoms that cluster during episodes of physiological instability. | Body temperature instability and respiratory morbidity in the very low birth weight infant: a multiple case, intensive longitudinal study | 10.1186/s12887-020-02351-y |
2020-10-19 | Background Direct seeding is an efficient cultivation technique in rice. However, poor low temperature germinability (LTG) of modern rice cultivars limits its application. Identifying the genes associated with LTG and performing molecular breeding is the fundamental way to address this issue. However, few LTG QTLs have been fine mapped and cloned so far. Results In the present study, the LTG evaluation of 375 rice accessions selected from the Rice Diversity Panel 2 showed that there were large LTG variations within the population, and the LTG of Indica group was significantly higher than that of Japonica and Aus groups ( p < 0.01). In total, eleven QTLs for LTG were identified through genome-wide association study (GWAS). Among them, qLTG_sRDP2–3/qLTG_JAP-3 , qLTG_AUS-3 and qLTG_sRDP2–12 are first reported in the present study. The QTL on chromosome 10, qLTG_sRDP2–10a had the largest contribution to LTG variations in 375 rice accessions, and was further validated using single segment substitution line (SSSL). The presence of qLTG_sRDP2–10a could result in 59.8% increase in LTG under 15 °C low temperature. The expression analysis of the genes within qLTG_sRDP2–10a region indicated that LOC_Os10g22520 and LOC_Os10g22484 exhibited differential expression between the high and low LTG lines. Further sequence comparisons revealed that there were insertion and deletion sequence differences in the promoter and intron region of LOC_Os10g22520 , and an about 6 kb variation at the 3′ end of LOC_Os10g22484 between the high and low LTG lines, suggesting that the sequence variations of the two genes could be the cause for their differential expression in high and low LTG lines. Conclusion Among the 11 QTLs identified in this study, qLTG_sRDP2–10a could also be detected in other three studies using different germplasm under different cold environments. Its large effect and stable expression make qLTG_sRDP2–10a particularly valuable in rice breeding. The two genes, LOC_Os10g22484 and LOC_Os10g22520 , were considered as the candidate genes underlying qLTG_sRDP2–10a . Our results suggest that integrating GWAS and SSSL can facilitate identification of QTL for complex traits in rice. The identification of qLTG_sRDP2–10a and its candidate genes provide a promising source for gene cloning of LTG and molecular breeding for LTG in rice. | The Candidate Genes Underlying a Stably Expressed QTL for Low Temperature Germinability in Rice (Oryza sativa L.) | 10.1186/s12284-020-00434-z |
2020-10-19 | Background The optimal time-response window for photobiomodulation therapy (PBMT) using low-level laser therapy (LLLT) and/or light emitting diodes therapy (LEDT) combined with static magnetic fields (sMF) before physical activity still was not fully investigated. The aim of the present study was to investigate the better of four time-response windows for PBMT combined with sMF (PBMT-sMF) use before exercise in humans. Methods A prospectively registered, randomized, triple-blinded (volunteers, therapists and assessors) placebo-controlled trial was carried out. Sixty healthy untrained male subjects were randomly allocated to six experimental groups ( n = 10 per group): PBMT-sMF 5 mins, PBMT-sMF 3 h, PBMT-sMF 6 h, PBMT-sMF 1-day, placebo, and control. The control group performed all procedures, however did not receive any kind of intervention. PBMT-sMF active or PBMT-sMF placebo was applied precisely in different time points after baseline MVC test to ensure that both MVC tests and eccentric exercise protocol would occur at the same hour of the day in all groups. Then, after five minutes, 3 h, 6 h or 1-day (24 h) of PBMT-sMF treatment (active or placebo) the eccentric exercise protocol was performed. The primary outcome was peak torque obtained from maximum voluntary contraction (MVC). The secondary outcomes were creatine kinase (CK), and delayed onset muscle soreness (DOMS). The primary and secondary outcomes were measured at baseline, immediately after, 1 h, 24 h and 48 h after the eccentric exercise protocol. Results Sixty patients were randomized and analyzed to each sequence. The outcomes in absolute values show that all active PBMT-sMF groups increased ( p < 0.05) MVC from immediately after to 1 h after eccentric exercise, and decreased (p < 0.05) CK activity at all time points. However, PBMT-sMF 5 mins, 3 h and 6 h groups showed better results in MVC and CK analysis from 24 h to 48 h, and also to DOMS ( p < 0.05) at all time points. Participants did not report any adverse events. Conclusions PBMT-sMF can be used from 5 min to 6 h before exercise, and the effects can last up to 54 h after treatment. However, the effects start to decrease when a 1-day (24 h) time-response window is used. Trial registration NCT03420391 . Registered 05 February 2018. | What is the optimal time-response window for the use of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) for the improvement of exercise performance and recovery, and for how long the effects last? A randomized, triple-blinded, placebo-controlled trial | 10.1186/s13102-020-00214-8 |
2020-10-17 | The measurement of physicochemical variables to infer water quality is important since they help determine the distribution and abundance of aquatic organisms or pollution-related problems. Recently, the development of low-cost probes is a suitable alternative for continuous monitoring of these variables rather than the use of expensive instruments. In this work, a low-cost multiparameter probe (LCMP) has been developed to monitor water quality in an estuary located in Northwestern Mexico during a 3-month period. The LCMP integrates different sensors to an Arduino Nano microcontroller allowing to measure electrical conductivity, dissolved oxygen, pH, salinity, water temperature, and tide level. Data files were stored in a data logger system consisting of a secure digital (SD) card module and a real-time clock module coupled to the Arduino microcontroller. To ensure continuous operation, the system was powered by four 3.7 V, 10,000 mAh rechargeable LiPo batteries. All LCMP components were encapsulated in a polyvinyl chloride pipe. The results show that the LCMP had a good agreement with a commercial-grade multiparameter probe and was able to monitor continuously in hourly time steps. Finally, the LCMP proved to be an alternative for the establishment of coastal observatories, which has been deficient due to limited funding. | Design and implementation of a low-cost multiparameter probe to evaluate the temporal variations of water quality conditions on an estuarine lagoon system | 10.1007/s10661-020-08677-5 |
2020-10-16 | Background Schizochytrium species are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids (PUFAs) in many species. This study investigates low-temperature effects on DHA biosynthesis in Schizochytrium sp. TIO01 and its underlying mechanism. Results The Schizochytrium fatty acid biosynthesis pathway was evaluated based on de novo genome assembly (contig N50 = 2.86 Mb) and iTRAQ-based protein identification. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are, respectively, responsible for DHA and saturated fatty acid synthesis in Schizochytrium . Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium , increasing the DHA content from 43 to 65% of total fatty acids. However, the expression levels of PKS pathway genes were not significantly regulated as the DHA content increased. Further, gene expression analysis showed that pathways related to the production of substrates (acetyl-CoA and NADPH) for fatty acid synthesis (the branched-chain amino acid degradation pathway and the pentose phosphate pathway) and genes related to saturated fatty acid biosynthesis (the FAS pathway genes and malic enzyme) were, respectively, upregulated and downregulated. These results indicate that low temperatures increase the DHA content by likely promoting the entry of relatively large amounts of substrates into the PKS pathway. Conclusions In this study, we provide genomic, proteomic, and transcriptomic evidence for the fatty acid synthesis pathway in Schizochytrium and propose a mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium . The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for investigating the regulation of polyunsaturated fatty acid biosynthesis and the evolutionary characteristics of Thraustochytriidae species. | Low-temperature effects on docosahexaenoic acid biosynthesis in Schizochytrium sp. TIO01 and its proposed underlying mechanism | 10.1186/s13068-020-01811-y |
2020-10-16 | Background RNA sequencing is a powerful approach to quantify the genome-wide distribution of mRNA molecules in a population to gain deeper understanding of cellular functions and phenotypes. However, unlike eukaryotic cells, mRNA sequencing of bacterial samples is more challenging due to the absence of a poly-A tail that typically enables efficient capture and enrichment of mRNA from the abundant rRNA molecules in a cell. Moreover, bacterial cells frequently contain 100-fold lower quantities of RNA compared to mammalian cells, which further complicates mRNA sequencing from non-cultivable and non-model bacterial species. To overcome these limitations, we report EMBR-seq (Enrichment of mRNA by Blocked rRNA), a method that efficiently depletes 5S, 16S and 23S rRNA using blocking primers to prevent their amplification. Results EMBR-seq results in 90% of the sequenced RNA molecules from an E. coli culture deriving from mRNA. We demonstrate that this increased efficiency provides a deeper view of the transcriptome without introducing technical amplification-induced biases. Moreover, compared to recent methods that employ a large array of oligonucleotides to deplete rRNA, EMBR-seq uses a single or a few oligonucleotides per rRNA, thereby making this new technology significantly more cost-effective, especially when applied to varied bacterial species. Finally, compared to existing commercial kits for bacterial rRNA depletion, we show that EMBR-seq can be used to successfully quantify the transcriptome from more than 500-fold lower starting total RNA. Conclusions EMBR-seq provides an efficient and cost-effective approach to quantify global gene expression profiles from low input bacterial samples. | Efficient and cost-effective bacterial mRNA sequencing from low input samples through ribosomal RNA depletion | 10.1186/s12864-020-07134-4 |
2020-10-15 | Realizing the efficiency benefits of low viscosity lubricants requires novel strategies to avoid failures resulting from increased boundary contact. Zirconium dioxide (ZrO 2 ) nanoparticles (NPs) form protective tribofilms through tribosintering at lubricated contacts in pure hydrocarbon base oils, suggesting they hold promise for reducing boundary contact-induced failures. However, their tribological behavior alongside co-additives found in fully formulated oils has not been examined in depth. Here, the macroscopic tribological performance of dispersed ZrO 2 NPs (1 wt% loading; 5 nm diameter nearly spherical ZrO 2 tetragonal phase NPs with organic capping ligands for oil solubility) with and without the presence of co-additives found in fully formulated commercial gear oils was studied using a mini-traction machine (MTM). The results show that ZrO 2 NPs reproducibly develop surface-bound ~ 100 nm thick tribofilms on both contacting surfaces under a wide range of rolling-sliding contact conditions, from 0 to 100% slide-to-roll ratio. Steady-state traction coefficient values of ZrO 2 tribofilms formed alongside co-additives (0.10–0.11) do not substantially differ from ZrO 2 tribofilms formed in neat polyalphaolefin base oils (0.10–0.13). However, there is improvement in the tribological performance of the contact, with at least a twofold reduction of wear of the steel. This behavior is proposed to be a result of cooperating mechanisms, where the extreme pressure additives adsorbed on the steel surfaces protect them against early adhesive wear, during the time that a protective ZrO 2 tribofilm incorporating the co-additives forms on the steel surfaces, preventing further wear. Graphic Abstract | Cooperativity Between Zirconium Dioxide Nanoparticles and Extreme Pressure Additives in Forming Protective Tribofilms: Toward Enabling Low Viscosity Lubricants | 10.1007/s11249-020-01346-1 |
2020-10-15 | Background In the current study, our specific aim was to characterize the Klotho protein and expression levels in the hippocampus and prefrontal cortex of old rats treated with different diets (high-fat, high-protein, low-calorie, high-protein and low-calorie). Methods Rats were treated with high-fat, high-protein, low-calorie, low-calorie high-protein diets for 10 weeks and then behavioral and molecular assessments were evaluated. Results Statistical analysis showed the percentage of open arm time was increased in the high-protein, low-calorie and low-calorie high-protein groups compared with old control (old-C) rats. The percentage of open arm entries was increased in the low-calorie and low-calorie high-protein group compared with old-C rats. The body weight and serum triglyceride were decreased in the low-calorie and low-calorie high-protein groups in comparison to control old rats. Low-calorie and low-calorie high-protein treatments statistically enhanced caspase-3 level compared with old-C rats in the hippocampus and prefrontal cortex. Treatment of old rats with high-protein, low-calorie and low-calorie high-protein could increase Klotho-α level compared with control old rats. The levels of Klotho-α, c-fos and brain-derived neurotrophic factors were decreased in the low-calorie high-protein group in Klotho inhibitor's presence compared with the low-calorie high-protein group. Conclusion According to our findings, Klotho-α level was reduced in old rats. Low-calorie, high-protein and particularly low-calorie high-protein diets increased this protein level and consequently increased neuronal plasticity and improved memory function. Graphic abstract | High-protein and low-calorie diets improved the anti-aging Klotho protein in the rats’ brain: the toxic role of high-fat diet | 10.1186/s12986-020-00508-1 |
2020-10-14 | Background The health impact of COVID-19 may differ in African settings as compared to countries in Europe or China due to demographic, epidemiological, environmental and socio-economic factors. We evaluated strategies to reduce SARS-CoV-2 burden in African countries, so as to support decisions that balance minimising mortality, protecting health services and safeguarding livelihoods. Methods We used a Susceptible-Exposed-Infectious-Recovered mathematical model, stratified by age, to predict the evolution of COVID-19 epidemics in three countries representing a range of age distributions in Africa (from oldest to youngest average age: Mauritius, Nigeria and Niger), under various effectiveness assumptions for combinations of different non-pharmaceutical interventions: self-isolation of symptomatic people, physical distancing and ‘shielding’ (physical isolation) of the high-risk population. We adapted model parameters to better represent uncertainty about what might be expected in African populations, in particular by shifting the distribution of severity risk towards younger ages and increasing the case-fatality ratio. We also present sensitivity analyses for key model parameters subject to uncertainty. Results We predicted median symptomatic attack rates over the first 12 months of 23% (Niger) to 42% (Mauritius), peaking at 2–4 months, if epidemics were unmitigated. Self-isolation while symptomatic had a maximum impact of about 30% on reducing severe cases, while the impact of physical distancing varied widely depending on percent contact reduction and R 0 . The effect of shielding high-risk people, e.g. by rehousing them in physical isolation, was sensitive mainly to residual contact with low-risk people, and to a lesser extent to contact among shielded individuals. Mitigation strategies incorporating self-isolation of symptomatic individuals, moderate physical distancing and high uptake of shielding reduced predicted peak bed demand and mortality by around 50%. Lockdowns delayed epidemics by about 3 months. Estimates were sensitive to differences in age-specific social mixing patterns, as published in the literature, and assumptions on transmissibility, infectiousness of asymptomatic cases and risk of severe disease or death by age. Conclusions In African settings, as elsewhere, current evidence suggests large COVID-19 epidemics are expected. However, African countries have fewer means to suppress transmission and manage cases. We found that self-isolation of symptomatic persons and general physical distancing are unlikely to avert very large epidemics, unless distancing takes the form of stringent lockdown measures. However, both interventions help to mitigate the epidemic. Shielding of high-risk individuals can reduce health service demand and, even more markedly, mortality if it features high uptake and low contact of shielded and unshielded people, with no increase in contact among shielded people. Strategies combining self-isolation, moderate physical distancing and shielding could achieve substantial reductions in mortality in African countries. Temporary lockdowns, where socioeconomically acceptable, can help gain crucial time for planning and expanding health service capacity. | Response strategies for COVID-19 epidemics in African settings: a mathematical modelling study | 10.1186/s12916-020-01789-2 |
2020-10-13 | We examine the renormalized free energy of the free Dirac fermion and the free scalar on a (2+1)-dimensional geometry ℝ × Σ, with Σ having spherical topology and prescribed area. Using heat kernel methods, we perturbatively compute this energy when Σ is a small deformation of the round sphere, finding that at any temperature the round sphere is a local maximum. At low temperature the free energy difference is due to the Casimir effect. We then numerically compute this free energy for a class of large axisymmetric deformations, providing evidence that the round sphere globally maximizes it, and we show that the free energy difference relative to the round sphere is unbounded below as the geometry on Σ becomes singular. Both our perturbative and numerical results in fact stem from the stronger finding that the difference between the heat kernels of the round sphere and a deformed sphere always appears to have definite sign. We investigate the relevance of our results to physical systems like monolayer graphene consisting of a membrane supporting relativistic QFT degrees of freedom. | Does the round sphere maximize the free energy of (2+1)-dimensional QFTs? | 10.1007/JHEP10(2020)078 |
2020-10-12 | Purpose The primary aim of this study is to assess, in an animal model, whether biostimulation of osteoporotic bone with low-level laser therapy improves the osseointegration of dental implants. Material and methods Twenty-two female rabbits were randomly divided into two groups: sham-ovariectomy and bilateral-ovariectomy. Laser therapy was applied to the implants placed in the right tibial bones and was not applied to implants placed in the left tibial bones. The periotest device was used for the stability test. Periotest values were recorded after the implantation (T0) and when the animals were euthanized (T1). The removal torque test and micro-computed tomography examination were evaluated. Results As a result of removal torque, the mean of ovariectomy-laser group (56.1 ± 5.1 Ncm) was higher than sham-ovariectomy group (55.4 ± 18.5 Ncm) ( p = 0.9). In periotest analysis, a significant difference was found between the values of T1 and T0 in all groups, except sham-ovariectomy group ( p < 0.05); and the highest difference was found in the ovariectomy-laser group. Micro-CT examination demonstrated that ovariectomy-laser group showed an increase of implant–bone contact when compared with ovariectomy ( p < 0.05). Conclusions The values obtained from biomechanical tests and micro-CT in the ovariectomy-laser group were significantly higher than the ovariectomy group and achieved the values in the healthy bone. | Effect of low-level laser therapy on osseointegration of titanium dental implants in ovariectomized rabbits: biomechanics and micro-CT analysis | 10.1186/s40729-020-00257-z |
2020-10-12 | Background Placental malaria (PM) is a major public health problem associated with adverse pregnancy outcomes such as low birth weight (LBW), preterm delivery and maternal anemia. The present study is aimed to determine the prevalence of placental malaria among asymptomatic pregnant women in Wolkite health center, Gurage zone, Southern Ethiopia. Method Facility-based cross-sectional study was carried out from June 2019 to August 2019. A total of 230 pregnant women were involved in the study where socio-demographic data, medical and obstetric history were collected using pretested structured questionnaires. Blood samples were collected at delivery from maternal capillary, placenta and umbilical cord for the detection of malarial parasite. Maternal hematocrit was determined to screen for anemia. Result In this study, the prevalence of placental malaria, peripheral malaria and umbilical cord malaria was 3.9% (9/230), 15.2% (35/230) and 2.6% (6/230) respectively. Plasmodium falciparum and Plasmodium vivax were detected by microscopy. All babies with positive umbilical cord blood films were born from a mother with placental malaria. Maternal anemia was recorded in 58.3% of the women. In univariate analysis, placental malaria was significantly associated with LBW ( p < 0.001) unlike parity and maternal anemia. Conclusion Placental malaria among asymptomatic pregnant women is low in Wolkite health centre, Gurage zone in Southern Ethiopia. Moreover, placental malaria was strongly associated with LBW. Thus, further strengthening the existing prevention and control activities and screening of asymptomatic pregnant women as part of routine antenatal care service is very essential. | Prevalence of placental malaria among asymptomatic pregnant women in Wolkite health center, Gurage zone, Southern Ethiopia | 10.1186/s40794-020-00121-3 |
2020-10-09 | U–Pb petrochronology of deep crustal xenoliths and outcrops across northeastern Tanzania track the thermal evolution of the Mozambique Belt and Tanzanian Craton following the Neoproterozoic East African Orogeny (EAO) and subsequent Neogene rifting. At the craton margin, the upper–middle crust record thermal quiescence since the Archean (2.8–2.5 Ga zircon, rutile, and apatite in granite and amphibolite xenoliths). The lower crust of the craton documents thermal pulses associated with Neoarchean ultra-high temperature metamorphism (ca. 2.64 Ga, > 900 °C zircon), the EAO (600–500 Ma rutile), and fluid influx during rifting (< 5 Ma apatite). Rutile in garnet granulite xenoliths exhibits partial Pb loss related to slow cooling of the lower crust after the EAO and suggests residence at 500–600 °C prior to entrainment. In contrast to the craton, the entire crust of the Mozambique Belt underwent differential cooling following the EAO. Both the upper and middle crust record metamorphism from 640 to 560 Ma (zircon, monazite, and titanite) and rapid exhumation at 510–440 Ma (rutile and apatite). Lower crustal xenoliths contain Archean zircon, but near-zero age rutile and apatite, indicating residence > 650 °C (above Pb closure of rutile and apatite) at the time of eruption. Zoned titanite records growth during cooling of the lower crust at 550 Ma, followed by fluid influx during slow cooling and exhumation (0.1–1 °C/Myr after 450 Ma). Permissible lower-crustal temperatures for the craton and orogen suggest variable mantle heat flow through the crust and reflect differences in mantle lithosphere thickness rather than advective heating from rifting. | Four-dimensional thermal evolution of the East African Orogen: accessory phase petrochronology of crustal profiles through the Tanzanian Craton and Mozambique Belt, northeastern Tanzania | 10.1007/s00410-020-01737-6 |
2020-10-09 | Major and trace element concentrations of thirteen limestone samples from zone XX of the Tlayúa Quarry Fossillagerstätte were analysed with the aim of elucidating the source of rare earth elements plus yttrium (REE+Y) as well as some palaeoenvironmental conditions attributable to them. The concentrations of cortex-derived elements/element oxides (SiO 2 , Al 2 O 3 , Zr), as well as of phosphorus, show no significant contamination by means of terrigenous material and/or phosphates, which means that the REE+Y concentrations can be interpretable. REE+Y patterns display partly typical modern seawater signals, particularly positive La and Y anomalies, mostly superchondritic Y/Ho ratios (between 42.34 and 56.38) and moderate depletions of light rare earth elements (LREE) and middle rare earth elements (MREE) in comparison to heavy rare earth elements (HREE) ( x̄ Pr SN /Yb SN = 0.12, x̄ Nd SN /Yb SN = 0.14 and x̄ Dy SN /Yb SN = 0.42, respectively). Negative cerium anomalies could also be identified [(Ce/Ce* SN ) = 0.73], which indicate oxidising conditions. In addition, positive Eu anomalies [(Eu/Eu* SN ) = 2.53] were detected. Since no convincing evidence for diagenesis, hydrothermal or aeolian input exists, the origin of these anomalies can, to some extent, be attributable to the influence of the dissolution of plagioclases in the water column, which can be inferred from the bivariate correlation of (Eu/Eu*) SN and Na/Al. Despite depicting modern seawater-like signals, an important difference between the REE+Y patterns from zone XX of the Tlayúa Quarry and modern seawater REE+Y patterns can be determined. For instance, modern seawater does not display significant europium anomalies. Nevertheless, REE+Y patterns from zone XX of the Tlayúa Formation can altogether be reliable palaeoenvironmental proxies for the Cretaceous. The inferred palaeoenvironment for zone XX from these proxies is represented by an open-marine setting, showing oxidising conditions, evidence of plagioclase dissolution and overall negligible terrigenous influence. The palaeoecological interpretation from these patterns does not exclude, however, the probability of monsoonal or tidally influenced sedimentation in other sediments from zone XX or from other zones in Tlayúa, as previous works suggest. | REE+Y patterns and positive europium anomalies recorded in limestones from zone XX of the Tlayúa Quarry Konservat-Lagerstätte (Tlayúa Formation, Lower Cretaceous; Tepexi de Rodríguez, Mexico) | 10.1007/s12517-020-06075-2 |
2020-10-08 | Main conclusion Early cytokinin activity and late abscisic acid dynamics during wheat kernel development correspond to cultivars with higher yield potential. Cytokinins represent prime targets for marker development for wheat breeding programs. Abstract Two major phytohormone groups, abscisic acid (ABA) and cytokinins (CKs), are of crucial importance for seed development. Wheat ( Triticum aestivum L.) yield is, to a high degree, determined during the milk and dough stages of kernel development. Therefore, understanding the hormonal regulation of these early growth stages is fundamental for crop-improvement programs of this important cereal. Here, we profiled ABA and 25 CK metabolites (including active forms, precursors and inactive conjugates) during kernel development in five field-grown wheat cultivars. The levels of ABA and profiles of CK forms varied greatly among the tested cultivars and kernel stages suggesting that several types of CK metabolites are involved in spatiotemporal regulation of kernel development. The seed yield potential was associated with the elevated levels of active CK levels ( t Z, c Z). Interestingly, the increased kernel c Z levels were followed by higher ABA production, suggesting there is an interaction between these two phytohormones. Furthermore, we analyzed the expression patterns of representatives of the four main CK metabolic gene families. The unique transcriptional patterns of the IPT (biosynthesis) and ZOG (reversible inactivation) gene family members (GFMs) in the high and low yield cultivars additionally indicate that there is a significant association between CK metabolism and yield potential in wheat. Based on these results, we suggest that both CK metabolites and their associated genes, can serve as important, early markers of yield performance in modern wheat breeding programs. | Cytokinin activity during early kernel development corresponds positively with yield potential and later stage ABA accumulation in field-grown wheat (Triticum aestivum L.) | 10.1007/s00425-020-03483-2 |
2020-10-07 | In this work, a tunneling field-effect transistor (TFET) in the structure that can maximize the electrostatic effects in determining its electrical performances is optimally designed and characterized. The featured device structure includes gate-all-around (GAA) channel and dual gates (DuGs) identified as control gate (CG) and adjust gate (AG), respectively. Not along with the design tasks, more fundamental studies on the effects of respective gates on device performances are sought. It has been found that the relatively different vicinities of the DuGs to source and drain junctions have differentiable dominances in controlling the primary direct-current (DC) parameters of the TFET including threshold voltage ( V th ), on-state current ( I on ), subthreshold swing ( S ), and on/off current ratio ( I on / I off ). For the systematic study, four different cases have been presumably schemed giving the degree of freedom in gate workfunctions and inter-gate connectivity. It has been found that the CG at the source side more effectively modulates V th , I off , and S , while the AG at the drain side shows the higher controllability over I on and I on / I off of the TFET. An optimally designed GAA DuG demonstrated I on / I off > 10 11 along with a small S of 14.6 mV/dec, which supports the strong potential of the GAA DuG TFET in the low-power applications. | More physical understanding of current characteristics of tunneling field-effect transistor leveraged by gate positions and properties through dual-gate and gate-all-around structuring | 10.1007/s00339-020-04015-1 |
2020-10-07 | The elastic behavior of low albite is investigated ab initio under hydrostatic pressure up to 16 GPa. Our calculations complement and extend previous studies confirming a highly anisotropic character of the feldspar cell compression and, more importantly, revealing a clear change of all structure deformation trends around 8–9 GPa pressure. We correlate this change to the trend of the bulk modulus of low albite as a function of pressure, which we compute in different and independent ways using (1) the Birch–Murnaghan equation of state, (2) the analytical Voigt–Reuss–Hill averaging scheme of calculated elastic constants, and (3) a pressure–volume numerical differentiation procedure. The latter, in particular, uncovers a singularity in the bulk modulus between 8 and 9 GPa pressure which is evocative of a $$\lambda$$ λ -type critical point. We find that the same behavior emerges when comparing with pressure–volume datasets from the experimental literature, where it has been so far overlooked due to the misleading use of a fourth-order Birch–Murnaghan equation of state. Indeed, we show that the equation of state must be extended up to at least the sixth power of the Eulerian strain to approximate the complex elastic behavior of feldspars. The low albite structure softens under increasing pressure between 5 and 8 GPa, as a result of the initiation of auxiliary compression mechanisms—notably, the squeezing of the crankshaft chains along b —and then abruptly resumes a stiffening trend in association with a displacive transformation of the O–O pair interactions. Whether this is an isosymmetric phase transition or a supercritical crossover, it suggests a compatibility with seismological profiles indicating a low wave-velocity anomaly in correspondence of the upper portion of the subducting Pacific plate and the disappearance of such anomaly at greater depths, assuming the alkali feldspar survives as a metastable phase. The data and methodology described here can enable the exploration of important, potentially overlooked features in other minerals, and inspire future high-pressure research in mineral physics. | Ab initio compressibility of metastable low albite: revealing a lambda-type singularity at pressures of the Earth’s upper mantle | 10.1007/s00269-020-01110-w |
2020-10-07 | Background Metabolic inflammation is an essential event in obesity-induced diabetes and insulin resistance. In obesity, an increasing number of macrophages recruited into visceral adipose tissues undergo significant M 1 -like polarization, secreting variable amounts of pro-inflammatory cytokines and causing insulin resistance. Piperine has excellent anti-inflammatory activities and may be used in the treatment of a variety of inflammatory diseases. In this study, we investigated the effect of piperine on adipose tissue inflammation and insulin resistance in obese mice. Methods Newborn mice were subcutaneously (s.c.) injected with monosodium glutamate (MSG) to establish a diabetes model. After 24 weeks, the MSG obese mice were divided into three groups and treated with piperine (40 mg/kg/day), metformin (150 mg/kg/day) and vehicle for 10 successive weeks, respectively. Results The obesity model was successfully established, as the body weight, insulin resistance, fasting blood glucose (FBG) and dyslipidemia were significantly increased. The 10-week administration of piperine to the obese mice not only significantly decreased the elevated FBG (Model: 6.45 ± 0.41 mM; Piperine: 4.72 ± 0.44 mM, p < 0.01), serum TC (Model: 5.66 ± 0.66 mM; Piperine: 3.55 ± 0.30 mM, p < 0.01) and TG (Model: 1.41 ± 0.08 mM; Piperine: 0.94 ± 0.05 mM, p < 0.001), but also enhanced the glucose infusion rate in the hyperglycemic clamp experiment. Meanwhile, piperine improved glucose intolerance and insulin resistance in MSG obese mice. Piperine markedly decreased the total and differential white blood cell (WBC) count, the serum levels of lipopolysaccharide (LPS) and pro-inflammatory cytokines such as galectin-3 (Gal-3) and interleukin-1β (IL-1β). Furthermore, piperine clearly down-regulated the mRNA levels of pro-inflammatory cytokines and the protein levels of M 1 -like polarization marker CD11c and Gal-3 in adipose tissues. The in vitro study showed that piperine inhibited LPS-stimulated polarization of RAW 264.7 cells toward the M 1 phenotype. Conclusions Piperine served as an immunomodulator for the treatment of obesity-related diabetes through its anti-inflammatory effects, which might be achieved by inhibiting macrophages M 1 polarization in adipose tissues. | Piperine ameliorates insulin resistance via inhibiting metabolic inflammation in monosodium glutamate-treated obese mice | 10.1186/s12902-020-00617-1 |
2020-10-05 | Background Burundi has one of the poorest child health outcomes in the world. With an acute malnutrition rate of 5% and a chronic malnutrition rate of 56%, under five death is 78 per 1000 live births and 47 children for every 1000 children will live until their first birthday. In response to this grim statistics, Village Health Works, a Burundian-American organisation has invested in an integrated clinical and community intervention model to improve child health outcomes. The aim of this study is to measure and report on child health indicator ahead of implementing this model. Methods A cross sectional design was employed, adopting the Demographic Health Survey methodology. We reached out to a sample of 952 households comprising of 2675 birth, in our study area. Mortality data was analysed with R package for mortality computation and other outcomes using SPSS. Principal component analysis was used to classify households into wealth quintiles. Logistic regression was used to assess strength of associations and significance of association was considered at 95% confidence level. Results The incidence of low birth weight (LBW) was 6.4% at the study area compared to 10% at the national level with the strongest predictor being malnourished women (OR 1.4 95%CI 1.2–7.2 p = 0.043 ). Fever incidence was higher in the study area (50.5%) in comparison to 39.5% nationally. Consumption of minimum acceptable diet was showed a significant protection against fever (OR 0.64 95%CI 0.41–0.94 p = 0.042 ). Global Acute Malnutrition rate was 7.6% and this significantly reduced with increasing age of child. Under-five mortality rate was 32.1 per 1000 live births and infant mortality was 25.7 per 1000 in the catchment with most deaths happening within the first 28 days of life (57.3%). Conclusion Improving child health status is complex, therefore, investing into an integrated intervention for both mother and child could yield best results. Given that most under-five deaths occurred in the neonatal period, implementing integrated clinical and community newborn care interventions are critical. | Infant and child health status ahead of implementation of an integrated intervention to improve nutrition and survival: a cross-sectional baseline assessment | 10.1186/s40795-020-00372-5 |
2020-10-03 | Digital light processing (DLP), a subclass of vat photopolymerization, is one of the most efficient additive manufacturing (AM) techniques that can be used to print complex objects with high precision at a greater speed than those of the other AM processes. However, printed objects are typically brittle because networks of cured resins are highly crosslinked, thereby limiting their range of possible applications. Currently, only a few commercial photocurable elastomers used for DLP can produce materials with moderate tensile strain, poor strength, and low modulus. Herein, we present a simple method for preparing photocurable resins that not only exhibit a low viscosity at room temperature, but also demonstrate tunable elasticity and strength. These novel resins are prepared from commercially available acrylate-based oligomers and monomers, which are appropriately selected to achieve a variety of mechanical properties. Subsequenlty, key parameters are investigated, including the viscosity of the uncured resin, critical energy at which the resin begins to solidify ( E c ), depth of penetration of the curing light ( D p ), and degree of curing. The viscosities of the developed resins range between 0.85 and 3.10 Pa s, and their curing and mechanical properties can be adjusted by varying the oligomer-to-monomer weight ratio. The E c (6.9–9.2 mJ cm −2 ) and D p (192–271 μm) of all the uncured resins are obtained from the working curves. The developed photoelastomers exhibit a wide range of tensile properties (tensile strain of 110–365%, tensile strength of 0.8–10 MPa, and modulus of 0.5–10 MPa), thereby facilitating their use in various applications. | Photocurable elastomers with tunable mechanical properties for 3D digital light processing printing | 10.1007/s10965-020-02289-w |
2020-10-01 | In order to reduce the sintering temperature of ceramics, the effects of binary composite sintering aids, Li 2 CO 3 and CuO, on the sintering temperature and properties of 0.7BiFeO 3 -0.3BaTiO 3 -0.0035MnCO 3 + 0.002Li 2 CO 3 + x CuO (BF-BT-LC + x CuO) ceramics were studied by traditional solid-state sintering. The results show that the sintering liquid phase can effectively promote the sintering of BF-BT-LC + x CuO ceramics by adding a certain amount of Li 2 CO 3 and changing the amount of CuO. The samples sintered at 930°C/2 h with 0.4 mol.% CuO get a piezoelectric constant d 33 = 168 pC/N, an electromechanical coupling coefficient k p = 0.302, and a mechanical quality factor Q m = 31.207. The addition of CuO was conducive to obtaining stable BF-BT-LC + x CuO piezoelectric ceramics. We conclude that the composite sintering aids, Li 2 CO 3 and CuO, can effectively promote the sintering of BF-BT-LC + x CuO, which is beneficial to obtain BF-BT-LC + x CuO ceramics with a wide sintering temperature range and stable properties. | Effects of Li2CO3 and CuO as Composite Sintering Aids on the Structure, Piezoelectric Properties, and Temperature Stability of BiFeO3-BaTiO3 Ceramics | 10.1007/s11664-020-08365-7 |
2020-10-01 | Low-temperature sintering of gahnite (ZnAl 2 O 4 ) ceramic, which has the potential to exhibit higher thermal conductivity than alumina but sinters densely at a moderate temperature of approximately 1500°C, has been investigated. When adding only 5 wt.% Cu-Nb-O additive, the sintering temperature was lowered significantly to 960°C. The sample fired at 960°C for 2 h exhibited a relative permittivity ( ε r ) of 9.1, a quality factor multiplied by resonant frequency ( Q × f ) value of 30,000 GHz (at a measurement frequency of approximately 13 GHz), and a temperature coefficient of resonant frequency ( τ f ) of −69 ppm/K, being relatively satisfactory values. However, the thermal conductivity of the sample was 9.3 W/m-K, which exceeds that of conventional low-temperature co-fired ceramic (LTCC) materials but is only one-third of that of the pure gahnite sample (27 W/m-K). Our analysis revealed that the main cause was the incorporation of the Cu component into the gahnite lattice. These results enable the proposal of guidelines for the development of new LTCC materials with high thermal conductivity. | Low-Temperature Sintering of Gahnite Ceramic Using Cu-Nb-O Additive and Evaluation of Dielectric and Thermal Properties | 10.1007/s11664-020-08346-w |
2020-10-01 | Abstract The structure and mechanical properties of 22K steel are studied during uniaxial tensile tests in the temperature range from room temperature to 1200°C. The temperatures above which the strength properties begin to decrease are determined. In the temperature range from room temperature to 950°C, austenite grain growth is shown to be almost absent. | Effect of High Temperatures on the Mechanical Properties of Grade 22K Steel | 10.1134/S0036029520100195 |
2020-10-01 | In the past few decades, low-temperature metals such as SUS304L, nickel alloys, and high-manganese steels have been widely used for liquefied natural gas (LNG) storage tanks to satisfy the structural integrity requirements at low temperature. Many researchers have conducted studies to characterize the fatigue and fracture performance of low-temperature metals. However, only a limited number of studies have considered the effects of various welding processes and consumables. This study addresses the fatigue and fracture performance of low-temperature metals while considering the effects of various alloying components. Moreover, we investigated the fatigue and fracture performance of various welding processes. Flux core arc welding (FCAW) was employed for both SUS304L and 9 wt.% nickel alloy steel, while tungsten inert gas (TIG) and shield metal arc welding (SMAW) were applied to SUS304L and 9 wt.% nickel alloy steel, respectively. Submerged arc welding (SAW) was employed for high-manganese steel. Fatigue and fracture tests were conducted according to ASTM E647 and BS 7448. The mechanical properties of the weld metals were systematically analyzed. SUS304L with FCAW exhibited excellent crack tip opening displacement (CTOD) and fatigue crack growth rate (FCGR). We also observed the microstructure of weld metals and discuss the mechanisms related to the fatigue and fracture performance in the parent and weld metals. | Investigation of fatigue and fracture characteristics for low-temperature metals considering the effects of various alloying components | 10.1007/s40194-020-00947-7 |
2020-10-01 | Today’s industrial technology offers to optimize and reutilize the resources available in terms of scum that remains after hot rolling in steel rerolling mills in Rajasthan, India. Vast reserves of low-grade coal exist and tons of mill scale are produced everyday after hot rolling in steel rerolling mills in Rajasthan, India. The present research work aimed to optimize the various parameters of solid-state reduction of mill scale using low-grade coal from Rajasthan, India. This study investigates the effect of reduction temperature (850–950 °C in steps of 50 °C), reduction time (60 to 180 min, in step of 60 min), mill scale size (800–300 μm), and mill scale to coal ratio (1:1, 1:2 and 1:3) on achievable metallic iron percentage and its metallization. A higher percentage of iron content is obtained at a lower particle size of 300 μm. The structural analysis is carried out on 300 μm mill scales using XRD analysis, which shows the percentage of iron is approximately 63%, and metallization above 80% can be obtained under the reduction temperature at 900 °C for 180 min, for 1:3 ratio (mill scale to coal ratio). The chemical composition of the mill scale is obtained using X-ray fluorescence (XRF), and particle sizes as well as distribution of mill scale are determined by scanning electron microscopy (SEM). The elements present in the mill scale are also verified using EDS, which indicates the presence of a major portion of Fe, followed by Fe 2 O 3 , Si, and C, respectively. | Synthesis and Characterization of Metallic Iron Reduced from Low-grade Coal in Rajasthan | 10.1007/s42461-020-00281-y |
2020-10-01 | The hot deformation behavior of an ultralow-carbon microalloyed steel was investigated using an MMS-200 thermal simulation test machine in a temperature range of 1 073–1 373 K and strain rate range of 0.01–10 s −1 . The results show that the flow stress decreases with increasing deformation temperature or decreasing strain rate. The strain-compensated constitutive model based on the Arrhenius equation for this steel was established using the true stress-strain data obtained from a hot compression test. Furthermore, a new constitutive model based on the Z -parameter was proposed for this steel. The predictive ability of two constitutive models was compared with statistical measures. The results indicate the new constitutive model based on the Z -parameter can more accurately predict the flow stress of an ultralow-carbon microalloyed steel during hot deformation. The dynamic recrystallization (DRX) nucleation mechanism at different deformation temperatures was observed and analyzed by transmission electron microscopy (TEM), and strain-induced grain boundary migration was observed at 1 373 K/0.01 s −1 . | Constitutive Modeling and Dynamic Recrystallization Mechanisms of an Ultralow-carbon Microalloyed Steel During Hot Compression Tests | 10.1007/s11595-020-2341-2 |
2020-10-01 | The present research investigated the effect of annealing temperature on surface gradient fine microstructure and wear resistance of low-carbon steel. The results depicted that the optimized annealing temperature from 300 °C to 400 °C can facilitate the formation of a stable fine microstructure. The fine grain size is about 0.2 μm on the topmost surface layer, and the percentage of grain boundary with misorientation angle of 1.5° is 26 %. The full width at half maximum values gradually decreases with increasing temperature from room temperature to 600 °C. In addition, the abrasive wear dominates the entire process for samples annealed at 300-400 °C. The wear mechanism gradually switches to adhesive wear and even delamination wear when the annealing temperature is increased to 500-600 °C. | Effect of Annealing Temperature on Surface Gradient Fine Microstructure and Wear Resistance of Low-Carbon Steel | 10.1007/s11665-020-05129-6 |
2020-10-01 | This study aimed to investigate the microstructure and mechanical properties of Ti x ZrVNb ( x = 1, 1.5, 2) refractory high-entropy alloys at room and elevated temperatures. The TiZrVNb alloy consisted of the body-centered cubic (bcc) matrix with a small amount of V 2 Zr phase. The Ti 1.5 ZrVNb and Ti 2 ZrVNb alloys exhibited a single-phase bcc structure. At room temperature, the tensile ductility of the as-cast alloys increased from 3.5% to 12.3% with the increase in the Ti content. The Ti x ZrVNb alloys exhibited high yield strength at 600°C, and the ultimate yield strength was more than 900 MPa. Softening occurred at 800°C, but the ultimate yield strength could still exceed 200 MPa. Moreover, the Ti x ZrVNb alloys displayed low densities but high specific yield strengths (SYSs). The lowest density of Ti x ZrVNb alloys was only 6.12 g/cm 3 , but the SYS could reach about 180 MPa·cm 3 ·g −1 , which is better than those of most reported high-entropy alloys (HEAs). | Effect of Ti content on microstructure and properties of TixZrVNb refractory high-entropy alloys | 10.1007/s12613-020-2040-1 |
2020-10-01 | Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas, and it is difficult to achieve simultaneous control of temperature and humidity. A combined absorption refrigeration (AR) and liquid desiccant dehumidification (LDD) air-conditioning system based on cascade utilization of low-grade heat source is proposed. The system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat sources. Under the design conditions, the heat utilization rate ζ reaches 21.05%, which is 2.73 times that of the conventional absorption refrigeration reference system. A parametric sensitivity analysis is performed to optimize the system. The ζ increases from 9.79% to 18.55% and the coefficient of performance COP t increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°C. With an increase in regenerant solution temperature from 60°C to 70°C, the ζ achieves the optimal value of 21.05% at 68°C. ζ decreases from 21.05% to 15.05% as the concentration of the regenerant solution increases from 36% to 40%. Under variable environmental temperature and humidity, the ζ of the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source, which indicates that the proposed system has a better adaptability to changing environmental parameters. | Performance Analysis of a Combined Absorption Refrigeration-Liquid Desiccant Dehumidification THIC System Driven by Low-Grade Heat Source | 10.1007/s11630-020-1363-6 |
2020-10-01 | A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr 0.9 FeNi 2.5 V 0.2 Al 0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients. | A new method of preparing high-performance high-entropy alloys through high-gravity combustion synthesis | 10.1007/s12613-020-2028-x |
2020-10-01 | Low-permittivity SrMgSi 2 O 6 microwave dielectric ceramics were synthesized via a conventional solid-state reaction method. Further, their sintering behavior as well as structural and microwave dielectric properties were studied. The x-ray diffraction patterns of the SrMgSi 2 O 6 and Sr 2 MgSi 2 O 7 ceramics were compared; both the samples were confirmed to be tetragonal. Meanwhile, the microwave dielectric properties of the samples were related to their microscopic morphology. In addition, the SrMgSi 2 O 6 ceramics had a low sintering temperature of 1125°C; they exhibited good microwave dielectric performances with a relative permittivity of ε r = 6.7, a quality factor Q × f = 25,800 GHz, and temperature coefficient of the resonator frequency τ f = −46 ppm/°C. Therefore, the ceramics exhibit potential for application in microwave devices. | Sintering Behavior and Microwave Dielectric Properties of Low-Permittivity SrMgSi2O6 Ceramic | 10.1007/s11664-020-08327-z |
2020-10-01 | A particular YSZ feedstock for very low-pressure plasma spraying (VLPPS) has been designed which can be automatically divided into less than 5 μm YSZ molten particles in the long plasma jet. Fully molten particles were deposited on the substrate at different deposition distances of 250, 350 and 450 mm, respectively. The deposition behavior of less than 5 μm YSZ molten particles were studied aiming to obtain a thin gastight YSZ coating. The flattening ratio of particles at different deposition distances and the gas permeability of YSZ coating prepared by VLPPS were investigated. The results revealed that the thickness of flattened particles was about 0.10-0.35 μm and the flattening ratio of molten particles was about 4.7. The flattened particles were bonded well with substrates and the width of vertical cracks appeared in flattened particles was 0.01-0.02 μm. The gas permeability of coatings prepared at 350 mm was 1.5 × 10 −7 cm 4 (gf) −1 s −1 . | Study on Deposition Behavior of Less Than 5 μm YSZ Particles in VLPPS | 10.1007/s11666-020-01087-6 |
2020-10-01 | Ion mobility spectrometers (IMS) are able to detect ppt V -level concentrations of substances in gasses and in liquids within seconds. Due to the continuous increase in analytical performance and reduction of the instrument size, IMS are established nowadays in a variety of analytical field applications. In order to reduce the manufacturing effort and further enhance their widespread use, we have developed a simple manufacturing process for drift tubes based on a composite material. This composite material consists of alternating layers of metal sheets and insulator material, which are connected to each other in a mechanically stable and gastight manner. Furthermore, this approach allows the production of ion drift tubes in just a few steps from a single piece of material, thus reducing the manufacturing costs and efforts. Here, a drift tube ion mobility spectrometer based on such a composite material is presented. Although its outer dimensions are just 15 mm × 15 mm in cross section and 57 mm in length, it has high resolving power of R p = 62 and detection limits in the ppt V -range, demonstrated for ethanol and 1,2,3-trichloropropane. | Novel ion drift tube for high-performance ion mobility spectrometers based on a composite material | 10.1007/s12127-020-00265-0 |
2020-10-01 | Vanadium oxide supported on TiO 2 (P25) catalysts were synthesized via atomic layer deposition (ALD) of vanadyl acetylacetonate (VO(acac) 2 ). Comprehensive investigations were performed to evaluate the ALD temperature window and the saturation deposition period of VO(acac) 2 , which were found to be 140–210 °C and 120 min, respectively. The synthesized catalysts were compared to their corresponding impregnation ones for the oxidative dehydrogenation of propane reaction (ODH-P). The ODH-P results indicated the superior performance of the ALD catalysts for the low temperature ODH-P (< 350 °C) given its better dispersion of vanadium oxide(vanadia) in the ALD catalysts. Several characterization techniques including HR-TEM, FE-SEM, XRD, BET, XPS, O 2 -chemisorption, ICP-OES, and H 2 -TPR were utilized to evaluate the influence of the ALD and impregnation methods of synthesis on different features of the catalysts. It was observed that the ALD method could offer far better dispersion of the active phase on the support of the catalyst, which is beneficial for the catalytic performance. Graphic Abstract Variations of Hacac, acetone, and CO 2 FTIR absorbance peaks’ areas versus the support temperature | Titania-Supported Vanadium Oxide Synthesis by Atomic Layer Deposition and Its Application for Low-Temperature Oxidative Dehydrogenation of Propane | 10.1007/s10562-020-03189-w |
2020-10-01 | OEGylated polypeptide bearing triethylene glycol monomethylether (OEG 3 ) and poly(ethylene glycol) methyl ether 350 (OEG 7 ) were first prepared by copper-mediated 1,3-dipolar cycloaddition. 1 H NMR, FTIR, and GPC results indicated the successful conjugation of oligo(ethylene glycol) (OEG) pendants with high grafting efficiency (≥ 98%). Variable temperature UV–vis spectroscopy revealed a reversible lower critical solution temperature (LCST)-type phase transition of the resulting polypeptides. The LCST-type cloud point temperature ( T cp ) in the range of 20–60 °C can be readily tuned by changing the OEG 3 and OEG 7 composition. Thermo- and pH-responsive polypeptide was prepared by first conjugating of OEG and 6-aldehyde hexyl pendants, then crosslinking in the presence of 1,6-hexanediamine, yielding OEGylated polypeptide bearing pH-labile imine bonds. The resulting polypeptide showed pH-responsive property and less pronounced thermoresponsive property at high pH values (i.e., ≥ 6.15) and noticeable thermo- and pH- dual responsive properties at low pH values (i.e., ≤ 5.80). Graphical abstract We developed a new type of pH- and thermo-responsive OEGylated polypeptides containing imine bonds. The polypeptides are able to show pH-responsive property and less pronounced thermoresponsive property at high pH values and noticeable thermo- and pH- dual responsive properties at low pH values. | Preparation and properties of thermo- and pH-responsive polypeptide bearing OEG and aldehyde pendants | 10.1007/s00396-020-04712-6 |
2020-10-01 | Simultaneous thermal analysis (TG–DTA) of low-rank coals from different annual periods (2015 and 2018) which originate from Kolubara and Nikola Tesla A (TENT A) coal-fired power plants was studied to identify their combustion characteristics and self-ignition risks. In order to investigate kinetics of thermo-oxidative degradation, model-free models including the Friedman and Kissinger–Akahira–Sunose methods were applied. In accordance with obtained kinetic results, numerical optimization of combustion process was implemented. Homogeneous and heterogeneous types of ignition were identified for the tested coals, and factors that affect their occurrence are the used heating rate and volatile matter content. From thermal susceptibility graph, it was found that the tested coals expand in a wide range of self-ignition risk, depending on their coal rank. The youngest coal (TENT A (2018)) has the largest propensity to self-ignite among high-ranking coals. It was found that less tendency of 2018 coals to show true isokinetic temperature in comparison with 2015 coals is a consequence of intraparticle diffusion limitations, and change of char properties, at higher conversion values. Gamma spectrometry analysis of coals showed that higher concentration of 40 K radionuclide (which is in mineral composition) may contribute through its deposition on available sites, decreasing surface area for reaction with oxidizing species. | Experimental study of low-rank coals using simultaneous thermal analysis (TG–DTA) techniques under air conditions and radiation level characterization | 10.1007/s10973-020-09288-5 |
2020-10-01 | In this paper, for developing the excellent composition ceramics for piezoelectric actuator application, the (1 − x)[(Na,K)(Nb,Sb)O 3 ]–(Bi,Na)ZrO 3 –xBaZrO 3 ceramics were fabricated according to BaZrO 3 substitution and the their physical characteristics were analyzed. An average grain size of the ceramics was slowly reduced according to BaZrO 3 addition. When x = 0.015, an excellent physical properties of density = 4.44 g/cm 3 , Q m = 95.47, k p = 0.403, ε r = 2041, and d 33 = 271pC/N were observed. These results show that the ceramics with x = 0.015 is an attractive candidate for lead-free piezoelectric actuator. | Physical Characteristics of (1 − x)[(Na,K)(Nb,Sb)O3]–(Bi,Na)ZrO3–xBaZrO3 Ceramics for Piezoelectric Actuator | 10.1007/s42341-020-00225-9 |
2020-10-01 | Abstract The thermal stability of the blends based on polylactide and low-density polyethylene of various compositions is studied. A decrease in the degradation temperature is observed with an increase in the polylactide content in samples (from 414°C for 100% polyethylene to 364°C for 100% polylactide). The influence of aged polyethylene on the thermooxidative degradation of the blends containing 30 wt % polylactide is studied. The third component (aged polyethylene) is determined to accelerate the initial oxidation stage. | Thermal and Thermooxidative Degradation of Blends Based on Polylactide and Polyethylene | 10.1134/S0036029520100213 |
2020-10-01 | The output power of the photovoltaic system is heavily dependent on the low voltage (LV) DC cables which are exposed to multiple stresses such as climatic, mechanical, electrical, and thermal stress, hence makes them more exposed to aging as compared to other components in the system. Accordingly, it is essential to monitor the state and know the real cause of the insulation degradation of the cable. The physio-chemical changes inside the insulation during service is attributed to the thermal stress, which the cable has to endure constantly. Traditionally, destructive test techniques have been adopted to study the aging phenomenon in the cable insulation, making them unsuitable for on-line condition monitoring. This research work has been aimed to study the degradation in LV photovoltaic DC cables under thermal stress by measuring the dielectric properties; complex permittivity, tanδ with the change in frequency and decay and return voltage slopes using extended voltage response method. The non-destructive diagnostic methods used are based on the phenomenon of polarization and conduction in the insulation material. The noteworthy change in the values of the imaginary part of permittivity, tanδ at low frequencies, and the overall decrease in the values of return voltage slope showed the change in the structure of the polymer matrix under the stress which was related to the cross-linking based chemical reactions. The results show that the techniques can be adopted for the on-line condition monitoring of the cable for the PV system and the dielectric parameters can be used to study the chemical and physical changes happening inside the material effectively. | Condition Assessment of Low Voltage Photovoltaic DC Cables under Thermal Stress Using Non-Destructive Electrical Techniques | 10.1007/s42341-020-00201-3 |
2020-10-01 | The 3-2-1 constraint principle has been widely applied as the boundary conditions for the finite element method (FEM) to simulate machining deformation of aerospace structure components. However, this principle is inconsistent with the actual contact surface between workpieces and worktables because it provides only three constraint points. These points have rarely been studied in terms of positions and distances. In addition, the applicability of the principle is limited for the workpiece with geometric centers difficult to find or centers without nodes. Therefore, this study proposed a new boundary condition method, low-stiffness spring element constraint method (SECM), drawing on FEM theories and related mechanic theories. With the method proposed this study established the FE model of machining deformation, and then compared the simulation results with both the analytical results and the experimental results of milling and deformation measurements. Good agreement is found between the three results. Finally, this study examined the effect of the three constraint points on simulation of the 3-2-1 principle in terms of point positions and distances. A comparison between SECM and the 3-2-1 principle revealed that SECM is closer to the actual working conditions and more reliable with wider application, which suggests that SECM can replace the 3-2-1 principle as the boundary conditions for the workpiece. | Low-stiffness spring element constraint boundary condition method for machining deformation simulation | 10.1007/s12206-020-0905-x |
2020-10-01 | Numerous equations have been proposed to describe the behavior of metal sheets under uniaxial tensile loading in the post-critical region. Here, the evolution of the cross-section is unknown and it is unclear which equation is most appropriate for which material. In this study, the evolution of the actual specimen cross-section is determined via digital image correlation (DIC); the data is then used to establish the post-necking stress-strain curve. Ultra-high-speed cameras were employed to capture the initiation of necking and fracture in zirconium low-oxidation (ZIRLO) sheets based on changes in the specimen cross-section. True stresses are calculated based on the actual cross-sectional area. The results indicate that the onset of local necking can be determined as the point at which the second derivative of the strain at different locations across the specimen cross-section diverge. The stress-strain data obtained by this rather direct method is considered more realistic than the data from conventional extrapolation method and is expected to be more appropriate in conjunction with a damage model. | Determination of post-necking stress-strain relationship for zirconium low-oxidation based on actual cross-section measurements by DIC | 10.1007/s12206-020-0913-x |
2020-10-01 | Anemometric method is the most accurate and reliable technique for air velocity measurement. In present work, a voltage follower based circuit is proposed, and a low-cost sensor (tungsten filament) is chosen to perform Constant Voltage Anemometer (CVA) operation for air velocity measurement. For performing the real-time experiment, a wind tunnel featuring a rectangular section (test section I) and a circular section (test section II) with a provision for low-cost sensors and a reference Hot Wire Anemometer (HWA) was fabricated. The measurement is repeated multiple times for various air velocities in the range of 3 m/s to 12 m/s. The estimated ‘pdr’ value (ratio of the power dissipated in the sensor, P w to the difference between heated sensor resistance, R w and the sensor resistance at ambient temperature, R a ), considered as new output voltage, is analogous with the output voltage (V o ) of the proposed circuit. The range of ‘pdr’ in test sections I and II is 0.033 mW/Ω to 0.867 mW/Ω and 0.0062 mW/ῼ to 0.1059 mW/Ω, respectively. Similarly, overheat ratio, OHR (ratio of the difference between heated sensor resistance, R w and the sensor resistance at ambient temperature, R a to the sensor resistance at ambient temperature, R a ) estimated, is also found to be analogous with the change in temperature (difference between the temperature of the heated sensor T w and the ambient temperature T a ). The range of OHR in test sections I and II is 0.709 to 0.660 and 0.678 to 0.647, respectively. Uncertainty analysis is carried out for the proposed voltage follower based CVA measurement system and the expanded uncertainty with a 95% confidence level is obtained as 0.54 for the whole range of air velocity measurement. | Realization of Constant Voltage Anemometer Using an Alternative Signal Conditioning Circuit | 10.1007/s40799-020-00379-4 |
2020-10-01 | In this study, waste cotton yarn was used for the removal of Pb (II), Cd (II), Cr (III), and As (V) from aqueous solution. Adsorption of heavy metal ions was tested from single ion solutions, while competitive studies were performed using two- and four-ion mixtures. In order to change the structure of the material, cotton yarn was modified by sodium hydroxide solution. The surface of raw and modified cotton yarn were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and streaming potential method for determination of an isoelectric point. Sorption studies were performed on the basis of pH, kinetics, isotherms, and desorption results. It has been shown that waste cotton yarn modification, typically, does not improve the sorption capacity of the material and that the unmodified material could be used for the removal of examined heavy metal ions. Selectivity was in order Pb > Cd > Cr > As. Desorption studies have indicated to the possible reusability of the sorbent only in the case of Pb removal. A potential application of spent waste sorbent for the soil quality improvement has been considered. | Application of waste cotton yarn as adsorbent of heavy metal ions from single and mixed solutions | 10.1007/s11356-020-09811-z |
2020-10-01 | Abstract Coral-like ZnO nanostructures were successfully grown onto heat-resistant flexible substrates by the oxidation of Zn thin films. At a relatively low temperature (100°C), Zn thin film was oxidized using a horizontal furnace under the flow of water vapour. The obtained results revealed well-defined aggregates of ZnO nanostructures grown on the flexible films. XRD patterns exhibited a strong and sharp diffraction along the (002) plane suggesting a well-crystallized ZnO phase. Field emission scanning electron microscopy observations showed high-density ZnO nanostructures aggregated in coral-like shape. The present study introduced a cost-effective and simple approach to grow high-quality ZnO nanostructures with controlled shape and size, offering a promising candidate for nano-based devices such as fast-response photodiodes and gas sensors. | Growth of ZnO Nanostructures by Wet Oxidation of Zn Thin Film Deposited on Heat-Resistant Flexible Substrates at Low Temperature | 10.1134/S1063782620100103 |
2020-10-01 | Background About 10 years ago, super-high energy Charpy specimens at the National Institute of Standards and Technology were removed from inventory due to unacceptable variability in absorbed energy, leading to the advent of new methods and materials to reduce the variability and maintain the prescribed energy levels. Objective In this paper, we investigated the ductile-to-brittle transitional behavior of Ni-Cr-Mo low-alloy steel by testing Charpy specimens with side-grooves as a function of the final temper temperature to define the processing conditions for these super-high energy levels. Methods For each temper, absorbed energy and force-displacement data were measured as a function of test temperature; the former was used to assess transition temperature and upper-shelf energy and the latter was used to estimate shear fracture appearance ( SFA ). Results From the upper-shelf energy results, it was found that two of the temper conditions yielded energies in the super-high energy range and that side-grooves reduced the variability of the energy by preventing the formation of shear lips. From the SFA data, it was shown that the instrumented striker data and fractography were in excellent agreement, with the minor discrepancies attributed to difficulties with transitional fracture surfaces in the fractography and multiple crack arrest points in the instrumented striker data. Conclusions In all, the data provided clear evidence that Ni-Cr-Mo low-alloy steel is a good solution for super-high energy Charpy indirect verification specimens. | Effect of Tempering on the Ductile-to-Brittle Transitional Behavior of Ni-Cr-Mo Low-Alloy Steel | 10.1007/s11340-020-00630-4 |
2020-10-01 | Abstract — The economic feasibility of substituting small-capacity coal-fired boiler houses with geothermal heat-pump units in the central ecological zone of the Baikal natural area is analyzed. Three versions of a space-heating system equipped with heat-pump units are considered depending on the source of low-grade heat and the method for extracting it: a well, a horizontal ground collector, and a water basin (Lake Baikal). The study is carried out for the raions of the Irkutsk oblast and the Republic of Buryatia located in the most favorable natural and climatic conditions in the southern part of the Baikal natural area’s central ecological zone, which have different economic conditions in terms of electricity tariffs and fuel cost. A conditional small-capacity coal-fired boiler house having averaged technical characteristics is taken as the base version for comparing it with heat-pump units. A monovalent mode of heat-pump unit operation is considered taking into account a shift for using a low-temperature space-heating system. The economic feasibility of substituting a coal-fired boiler house is estimated proceeding from the equality between the total discounted costs for implementing a space-heating system equipped with heat-pump units and costs for operation of the coal-fired boiler house for the considered period of time. The dependences of the total discounted costs for the alternatives being compared have been obtained, using which it is possible to determine the level of electricity tariffs and coal prices at which the application of heat-pump units in the studied region becomes economically feasible. The influence of possible deviations of the conditions in a particular locality from the conditions typical for the analyzed regions that were adopted for consideration is taken into account. It can be concluded from the obtained results that, given the current prices for coal and electricity, it is not economically feasible to substitute small-capacity coal-fired boiler houses with heat-pump units under the natural and climatic conditions of the considered regions. The use of heat-pump units may become justified with a coal price equal to 5000–8000 rubles/t and electricity tariffs equal to 2–4 rubles/(kW h); in this case, the discounted payback period of investments will make approximately 30 years. | Feasibility Study of Using Geothermal Heat-Pump Units for Substituting Small-Capacity Coal-Fired Boiler Houses (Taking the Baikal Natural Area as an Example) | 10.1134/S0040601520100055 |
2020-10-01 | Potato cultivars are propagated by tubers which are sensitive to damage by freezing. Potato has about 100 related wild Solanum species growing naturally in the Americas. When tubers of a spectrum of these species were slowly cooled, most were killed at a few degrees below 0 C. Only tubers of Solanum jamesii , native to the southwest USA, remained firm, sprouted and grew after one week exposure to freezing temperatures as cold as -15C. Differential Thermal Analysis was performed to detect low temperature exotherms (LTEs) in jamesii and similar-sized tubers of cultivars Russet Burbank and Snowden. LTEs, indicating supercooling, were detected only in the jamesii tubers. Survival of potato tubers at freezing temperatures could be useful in several ways. Even non-lethal cold exposure of potato tubers at harvest reduces quality for eating and for seed, but storage at freezing temperatures without damage could help preserve tuber dormancy and limit diseases. Las variedades de papa se propagan por tubérculos, que son sensibles al daño por congelamiento. La papa tiene como 100 especies silvestres de Solanum relacionadas que crecen de forma natural en las Américas. Cuando enfriamos tubérculos lentamente en un espectro de esas especies, la mayoría murió a unos cuantos grados de 0 °C. Solo tubérculos de Solanum jamesii, nativa del suroeste de EUA, permanecieron firmes, brotaron y crecieron después de una semana de exposición a temperaturas congelantes tan frías como a − 15 °C. Se condujo un análisis diferencial térmico para detectar exotermas de baja temperatura (LTEs) en jamesii y en tubérculos de tamaño similar de las variedades Russet Burbank y Snowden. Se detectaron LTEs indicando super enfriamiento solo en los tubérculos de jamesii. La sobrevivencia de los tubérculos de papa a temperaturas congelantes pudiera ser útil de varias maneras. Aún la exposición a temperaturas frías no letales de tubérculos de papa en la cosecha reduce la calidad para ingestión y para semilla. Por otro lado, la sobrevivencia a temperaturas congelantes en el almacén pudiera ayudar a preservar la dormancia de los tubérculos y limitar las enfermedades. | Survival of Solanum jamesii Tubers at Freezing Temperatures | 10.1007/s12230-020-09797-x |
2020-10-01 | The so-called low-density steels have generated a lot of interests with their high specific strength and ductility due to the addition of the light element Al. In order to accelerate the low-density steel design, a thermodynamic database has been developed within the present author group. Two Al-containing systems, i.e., Cr–Al–C and Ni–Al–C, were modeled and optimized with CALPHAD approach based on the reliable binary descriptions. For Cr–Al–C system, the Gibbs energy of Cr 2 AlC phase was described by a temperature-dependent polynomial with the aid of the experimental data on the heat capacity, instead of estimating heat capacity from Neumann–Kopp rule. The incongruent melting temperature of Cr 2 AlC is 1762 K with the invariant reaction of liquid + Cr 3 C 2 + Al 4 C 3 → Cr 2 AlC. The phase equilibria between Cr 2 AlC and binary phases were well reproduced by using the present model parameters. For Ni–Al–C system, the liquid, fcc and bcc phases have been optimized to fit the carbon solubility in these three phases. A good agreement between the calculated and experimental data has been obtained using the present description of Ni–Al–C system. The reliable descriptions of the two ternary systems developed in the present work can be implemented into the thermodynamic database for low-density steels. | Thermodynamic modeling of Cr–Al–C and Ni–Al–C systems for low-density steels | 10.1007/s42243-020-00415-y |
2020-10-01 | Abstract Improvement of electrical insulating and adhesion characteristics of epoxydian resins cured with aminoimidazoline curing agents is considered. It is determined that necessary characteristics of fabricability (low viscosity and time of curing) and adhesion and cohesion strength to various metal substrates (steel, latten brass, coper, and aluminum) require low-viscous aminoimidazoline curing agents along with epoxy active diluents. The reasonability and effectiveness of combined action of the solutions of the products of condensation represented by Mannich bases containing imidazoline rings and initial aminoimidazolines as curing agents is demonstrated. | Fast-Setting Low-Viscous Epoxy Compositions for Impregnation and Adhesion of Electrotechnical Products | 10.1134/S1995421220040206 |
2020-10-01 | In the present investigation, an attempt has been made to investigate the replacement compatibility of conventional austenitic stainless steel (316L) with low-Ni austenitic stainless steel (201) by employing their dissimilar welding using gas tungsten arc welding technique with varying heat input. The effects of heat input on the microstructural, mechanical, and corrosion properties were studied. The result depicts the balanced austenite/ferrite content in the fusion zone for both the heat inputs. The low heat input process, which results in a faster cooling rate, demonstrates higher tensile strength and microhardness. Similarly, the pitting corrosion resistance of the fusion zone demonstrates better properties on the low heat input process attributed to the lesser dendritic length and lesser interdendritic arm spacing. | Effect of Heat Input on the Microstructural, Mechanical, and Corrosion Properties of Dissimilar Weldment of Conventional Austenitic Stainless Steel and Low-Nickel Stainless Steel | 10.1007/s13632-020-00681-y |
2020-10-01 | Aims Plant growth in the Arctic is often nutrient limited due to temperature constraints on decomposition and low atmospheric input of nitrogen (N). Local hotspots of nutrient enrichment found in up to 4000-year-old archaeological deposits can be used to explore the recycling and long-term retention of nutrients in arctic ecosystems. Methods We investigated old Inuit and Norse deposits (known as middens) and adjacent tundra ecosystems along a wet-dry fjord gradient in western Greenland to explore the isotopic fingerprinting of plant and soil carbon and nitrogen ( 13 C/ 12 C and 15 N/ 14 N) derived from human presence. Results At all locations we observed a significant isotopic fingerprint in soil and plant N related to human deposits. This demonstrates a century-long legacy of past human habitation on plant and soil characteristics and indicates a surprisingly high N retention in these ecosystems. This is consistent with the significantly higher plant biomass in areas with archaeological deposits. Conclusion Vegetation composition and N in plants and soils displayed marked differences along the wet-dry fjord gradient. Furthermore, the profound nutrient enrichment and organic matter accumulation in archaeological deposits compared to surrounding tundra demonstrates a century-long legacy of past habitation on plant and soil characteristics as well as efficient N cycling with surprisingly limited N loss. | Nitrogen isotopes reveal high N retention in plants and soil of old Norse and Inuit deposits along a wet-dry arctic fjord transect in Greenland | 10.1007/s11104-020-04683-1 |
2020-10-01 | Polymer-based EOR methods in low-permeability reservoirs face injectivity issues and increased fracturing due to near wellbore plugging, as well as high-pressure gradients in these reservoirs. Polymer may cause pore blockage and undergo shear degradation and even oxidative degradation at high temperatures in the presence of very hard brine. Low-tension gas (LTG) flooding has the potential to be applied successfully for low-permeability carbonate reservoirs even in the presence of high formation brine salinity. In LTG flooding, the interfacial tension between oil and water is reduced to ultra-low values (10 −3 dyne/cm) by injecting an optimized surfactant formulation to maximize mobilization of residual oil post-waterflood. Gas (nitrogen, hydrocarbon gases or CO 2 ) is co-injected along with the surfactant slug to generate in situ foam which reduces the mobility ratio between the displaced (oil) and displacing phases, thus improving the displacement efficiency of the oil. In this work, the mechanism governing LTG flooding in low-permeability, high-salinity reservoirs was studied at a microscopic level using microemulsion properties and on a macroscopic scale by laboratory-scale coreflooding experiments. The main injection parameters studied were injected slug salinity and the interrelation between surfactant concentration and injected foam quality, and how they influence oil mobilization and displacement efficiency. Qualitative assessment of the results was performed by studying oil recovery, oil fractional flow, oil bank breakthrough and effluent salinity and pressure drop characteristics. | Low-tension gas process in high-salinity and low-permeability reservoirs | 10.1007/s12182-020-00455-9 |
2020-10-01 | Low-cycle fatigue (LCF) behaviors of a second-generation nickel-based single-crystal superalloys with [001] orientation at 760 °C have been investigated. Different strain amplitudes were introduced to investigate the creep-fatigue effects. The LCF life of none tensile holding (NTH) was higher than that of the 60-s tensile hold (TH) at any strain amplitude. As the strain amplitude was 0.7%, the stacking and cross-slip dislocations appeared together at the γ/γ’ coherent microstructure in both TH and NTH specimens. At the strain amplitude of 0.9%, plenty of the cross-slip dislocations appeared in γ channel and other dislocations were stacking at γ/γ’ interfaces. However, the SFs still appeared in γ’ phase with 60-s TH which caused cyclic softening. As the strain amplitude increased up to 1.2%, the dislocations are piling up at the γ/γ’ interfaces and cutting through the γ’ phase in both TH and NTH tests, which caused cyclic hardening. The influences of strain amplitude and holding time were complicated. Different stress response behaviors occurred in different loading conditions. The surface characteristic and fracture mechanism were observed by scanning electron microscopy. This result is helpful for building the relationship of various blade fatigue failure modes, cyclic stress response and microstructure deformation under different strain amplitudes. | Low-Cycle Fatigue and Creep-Fatigue Behaviors of a Second-Generation Nickel-Based Single-Crystal Superalloy at 760 °C | 10.1007/s40195-020-01056-6 |
2020-10-01 | In this lecture an overview of applications of incoherent Thomson scattering (TS) as well as collective Thomson scattering (CTS) will be given. These are the most accurate methods for measuring the electron and ion properties, because the method is direct and non-intrusive. A CTS system based on the fundamental wavelength of a seeded Nd:YAG laser, being developed for the high density, low-temperature plasma of the linear plasma generator Magnum-PSI will be described also. The small Debye length of dense low temperature plasma enables application of CTS at relatively short laser wavelength. The combination of this CTS system and existing incoherent TS system enables determination of electron density and temperature as well as ion temperature and plasma velocity of the near surface plasma. In this lecture, the theoretical background and experimental challenges of the work will be given along with some examples that demonstrate the capabilities of such systems. | Incoherent and Collective Thomson Scattering for the Determination of Electron and Ion Properties in Low-Temperature Plasma | 10.1007/s10894-020-00262-5 |
2020-10-01 | Abstract Anionic dyes are often used for conventional cotton dyeing. This process, however, has a moderate affinity and it is estimated that less than 70% of the dye interacts with the cotton fiber. Cationization of cellulose is a chemical treatment that modifies the cellulose molecule, making it strongly cationic. This pretreatment increases the affinity between cotton and anionic dyes. Therefore, cationic dyeing reduces water, time, energy and chemical consumption. In this scenario, there is a growing demand to develop new cleaner products, as well as to elucidate the reaction mechanism aiming to create a clean and low-cost process for cotton cationization. In the last decades, more than 800 documents were published, and this number continues to rise. Among the cationic agents, 3-chloro-2-hydroxypropyl trimethylammonium chloride is the most researched and has achieved niche markets. However, poly-diallyldimethylammonium chloride combines effectiveness with a cleaner process. These characteristics make this cationic agent promising for future research. This review reports the state of the art on the techniques used for cationization, with a brief description of the market available for cationic cotton and a critical evaluation of the future perspectives for cationization. Graphic abstract | Cationization of cotton fiber: an integrated view of cationic agents, processes variables, properties, market and future prospects | 10.1007/s10570-020-03361-w |
2020-10-01 | Boron nitride (BN) multi-layers are proposed as dielectric material for both horizontal and vertical graphene nanoribbon interconnects. The layer number dependence of the out-of-plane dielectric constant of BN multi-layers is utilized to simultaneously reduce the interlayer dielectric thickness and the crosstalk delay at 7 nm CMOS technology node. Since crosstalk effects are manifested more strongly in denser interconnects, the proposed all-two-dimensional-materials-based interconnection schemes are compared with Cu/low-k technology in terms of crosstalk delay. Results show that by reducing the interlayer dielectric thickness from 20 nm to 2 nm, the crosstalk delay ratio of the horizontal and vertical graphene nanoribbon interconnects to the Cu/pSiCOH counterparts decreases by 27.06% and 12.86%, respectively. It is also shown that as the interconnect length increases, both horizontal and vertical graphene nanoribbon interconnects with the BN dielectric prove more advantageous than the Cu/low-k counterparts. | All-2D-Materials-Based Interconnects | 10.1007/s11664-020-08289-2 |
2020-10-01 | We present a sensitive voltage amplifier suited for measurements of source impedances in the k $$\Omega$$ Ω range at dilution refrigerator temperatures. The circuit is based on a commercial dc SQUID, an impedance matching transformer, and it works on the principle of negative feedback. At 10 mK, the amplifier contribution to the noise is only 17 $$\text{pV/}\sqrt{\text{ Hz }}$$ pV/ Hz , which is negligible in comparison with the fluctuations of the thermal voltage of a 3.25 k $$\Omega$$ Ω metallic source resistor. Various circuit parameters of the amplifier are discussed. | A SQUID-Based Picovoltmeter for Quantum Resistors | 10.1007/s10909-020-02388-4 |
2020-10-01 | As a matrix resin of silica/epoxy hybrid encapsulation material with high heat resistance and low coefficient of thermal expansion, a tri-functional triglycidyl p-aminophenol (TGPAP) epoxy was successfully synthesized with the desired chemical structure by reacting epichlorohydrin with p-aminophenol using sodium hydroxide catalyst. In order to produce highly pure TGPAP with lower viscosity, a physical thin film vacuum distillation was carried out after synthesis, resulting in 97% purity with the viscosity of 700 cps at room temperature. Silica/TGPAP hybrid was fabricated using two kinds of ground fumed silica with different sizes of 20 μm and 9 μm. Glass transition temperature of the hybrid was found to be as high as 185 °C. Viscosity of the hybrid was 30,000 cps at room temperature before curing, implying good processability. When two different sizes of silica were used with 1 to 1 weight ratio, very low coefficient of thermal expansion of 22.79 ppm/°C was obtained. From thermal shock test, no cracks were observed even after 1,000 cycles of thermal shock between −40 °C and 125 °C when 67 wt% (45.8 vol%) of silica was involved in the hybrid. In conclusion, silica/TGPAP hybrid with improved processability, superior thermal shock resistance and low thermal expansion coefficient could be fabricated as electronic device encapsulation. | Silica/Epoxy Hybrid Encapsulation with High Heat-Resistance and Low Coefficient of Thermal Expansion | 10.1007/s13233-020-8135-8 |
2020-10-01 | The development of ball grid array (BGA) packages, such as the chip scale package, wafer level package and package on package, has focused on creating electronics packages that are smaller, thinner, higher-performance and capable of higher functionality, among other desirable traits. Among the interconnection materials used in BGA packages, the Cu-core solder ball (CCSB) has many advantages, such as the use of finer pitch, improved electrical conductivity and better controllability of the coplanarity of the chip. In this study, we evaluated the mechanical properties of the CCSB and Sn-3.0Ag-0.5Cu (SAC) by low-speed shear tests, and the von Mises stress distribution and plastic strain distribution were simulated using a finite element method. The diameter of each solder ball was 280 μm, and the outer layer of the CCSB was a plated SAC layer. The shear strength of the CCSB was about 10% greater than that of SAC. The maximum value of the simulated von Mises stress for the CCSB was higher than that of SAC because the Cu-core is stiffer than SAC. The fracture energy of the CCSB decreased by about 50% compared to that of SAC. The maximum value of simulated plastic strain, which is associated with fracture surfaces, was higher with the CCSB than with SAC. We can thus conclude that the Cu-core in the CCSB affects the shear strength and fracture behavior of solder joints. | Mechanical Properties of Cu-Core Solder Balls with ENEPIG Surface Finish | 10.1007/s11664-020-08338-w |
2020-10-01 | The paper focuses on minor metals and coupled elements and aspires to understand individual incidents of imbalance on the mineral markets during the last 100 years and gain insight into the acting dynamics—those dynamics are commodity-specific but remain largely unchanged in their nature to date—and to identify the factors in play. The conclusions allow for a critical analysis of the widespread security-of-supply narrative of industrialized countries. They point at a market that is mostly a buyers’ market, in which prices and their volatility are largely dictated by shifting demand patterns and much less by supply constraints. Neither high country concentration nor poor governance seem to have a substantial or lasting impact on market balance. Short-term market imbalances are generally neutralized by a dynamic reaction on the demand side via substitution, efficiency gains or technological change. The paper also assesses the impact of those quickly shifting demand patterns and the related price volatilities on producing countries. It shows how mineral price volatilities can expose developing countries’ economies to significant economic risk, if their economy is heavily dependent on mineral production. Two cases that illustrate country exposure are explored in detail—the saltpeter crisis in Chile and the tin crisis in Bolivia. Both led to state bankruptcy. The paper concludes with an attempt to quantify economic exposure of producing countries to price volatilities of specific metals and suggests policies that adapt to the characteristic challenges of highly volatile demand. | Volatility drivers on the metal market and exposure of producing countries | 10.1007/s13563-019-00200-8 |
2020-10-01 | The Nationally Determined Contributions (NDCs) to the Paris Agreement (PA) submitted so far do not put the world on track to meet the targets of the Agreement and by 2020 countries should ratchet up ambition in the new round of NDCs. Brazil’s NDC to the PA received mixed reviews and has been rated as “medium” ambition. We use the Brazil Land Use and Energy System (BLUES) model to explore low-emission scenarios for Brazil for the 2010–2050 period that cost-effectively raise ambition to levels consistent with PA targets. Our results reinforce the fundamental role of the agriculture, forest, and land use (AFOLU) sectors and explore inter-sectoral linkages to power generation and transportation. We identify transportation as a prime candidate for decarbonization, leveraging Brazil’s already low-carbon electricity production and its high bioenergy production. Results indicate the most important mitigation measures are electrification of the light-duty vehicle (LDV) fleet for passenger transportation, biodiesel and biokerosene production via Fischer-Tropsch synthesis from lignocellulosic feedstock, and intensification of agricultural production. The use of carbon capture and storage (CCS) as well as netzero deforestation make significant contributions. We identify opportunities for Brazil, but synergies and trade-offs across sectors should be minded when designing climate policies. | Brazil’s emission trajectories in a well-below 2 °C world: the role of disruptive technologies versus land-based mitigation in an already low-emission energy system | 10.1007/s10584-020-02856-6 |
2020-10-01 | To valorize starchy waste from rice noodle factory, bioconversion of gelatinized starchy waste (GSW) to value-added product as L(+)-lactic acid, the monomer for polylactate synthesis, was investigated using amylolytic lactic acid bacterium, Enterococcus faecium K-1. Screening for appropriate nitrogen source to replace expensive organic nitrogen sources revealed that corn steep liquor (CSL) was the most suitable regarding high efficacy for L(+)-LA achievement and low-cost property. The successful applying statistic experimental design, Plackett-Burman design incorporated with central composite design (CCD), predicted the maximum L(+)-LA of 93.07 g/L from the optimized medium (OM) containing 125.7 g/L GSW and 207.3 g/L CSL supplemented with CH 3 COONa, MgSO 4 , MnSO 4 , K 2 HPO 4 , CaCl 2 , (NH 4 ) 2 HC 6 H 5 O 7 , and Tween80. Minimizing the medium cost by removal of all inorganic salts and Tween80 from OM was not an effect on L(+)-LA yield. Fermentation using the optimized medium without minerals (OM-Mi) containing only GSW (125.7 g/L) and CSL (207.3 g/L) in a 10-L fermenter was also successful. Thinning GSW with α-amylase from Lactobacillus plantarum S21 increased L(+)-LA productivity in the early stage of 24-h fermentation. Not only showing the feasible bioconversion process for GSW utilizing as a substrate for L(+)-LA production, this research also demonstrated the efficient model for industrial starchy waste valorization. | Utilizing Gelatinized Starchy Waste from Rice Noodle Factory as Substrate for L(+)-Lactic Acid Production by Amylolytic Lactic Acid Bacterium Enterococcus faecium K-1 | 10.1007/s12010-020-03314-w |
2020-10-01 | The Schrödinger equation for a system of two mobile spinless nuclei with $$\mathcal{Z}=2$$ Z = 2 and four electrons ( $$^4$$ 4 He $$_2$$ 2 -dimer) has been solved with exact diagonalization approach. It is found that the ground state of the system ( $$\sim -~4.2$$ ∼ - 4.2 a.u.) is higher than the energy of two separate $$^4$$ 4 He atoms ( $$\sim -~5.7$$ ∼ - 5.7 a.u.), and the average internuclear distance $$\langle R_0\rangle \sim 1.7~\AA $$ ⟨ R 0 ⟩ ∼ 1.7 Å is a half smaller than the typical lattice constant in solid helium phases. This result corresponds to a metastable state which can be stabilized only at extremely high external pressure estimated as 27,000 GPa. It means that formation of condensed helium phases at saturated vapor pressure (SVP) is possible only due to many-particle interaction. Below 4.2 K at SVP, $$^4$$ 4 He behaves as simple liquid without long-range ordering (He I phase), but below 2.17 K it undergoes the $$\lambda $$ λ -transformation into He II phase due to long-range antiferromagnetic ordering in the $$^4$$ 4 He spin subsystem with exchange of order 10 K. As a result, the He II phase can be interpreted as ‘spin ice’ built as polytypic structure of close-packed 2D planes on triangular lattice collected in a stack with alternated ordering in the direction perpendicular to the basal planes, but without breaking the closest packing principle between neighboring planes. | Interatomic Interaction and Structural Ordering in He II Phase | 10.1007/s10909-019-02303-6 |
2020-10-01 | Abstract — The modern state in design, calculation, and operation of heaters used in the steam-turbine regeneration systems in Russia and abroad is reviewed and analyzed. The first part of the article gives a list of companies producing steam-turbine feedwater heaters and the market shares occupied by the countries producing these apparatuses. The ranges of operating parameters for the feedwater heaters of Russian and foreign steam turbines are indicated. The article gives the types of heat exchangers included in the regenerative feedwater heating system and serving as high- and low-pressure heaters that are adopted in Russia and abroad, including contact apparatuses and plate-type heaters. Specific examples of arranging such apparatuses at power plants in different countries are given. Advantages and drawbacks associated with the use of contact and plate-type apparatuses as turbine unit feedwater heaters are discussed. Different designs of shell-and-tube high- and low-pressure feedwater heaters adopted in the United States, Europe, and Russia are presented. The designs of particular high- and low-pressure heaters characteristic of different domestic and foreign producers are described. Methods for arrangement and structural makeup of different functional areas of the heater’s heat-transfer surface are shown. The advantages and drawbacks of header-and-helical coil-type high-pressure heaters and tubular apparatuses for the similar purpose, including chamber-type apparatuses, are discussed in terms of thermal efficiency, reliability, and repairability. It follows from the presented data that there is no commonly accepted approach to designing the considered apparatuses, and that there is mutual influence of manufacturing experience, design trends, and heater manufacturing traditions in different countries. | State of the Art and Trends in the Design and Operation of High- and Low-Pressure Heaters for Steam Turbines at Thermal and Nuclear Power Plants in Russia and Abroad: Part 1. Heater Types and Designs | 10.1134/S004060152010002X |
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