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2021-08-01 | The pure phase (Zr 0.8 ,Sn 0.2 )TiO 4 nano crystals have been prepared by hydrothermal-molten salt method. The effects of the pH of solvent system, the calcinations temperature and the ratio of composite molten salt on the phase composition and crystalline morphology have been investigated. The results show that the high pure phase (Zr 0.8 ,Sn 0.2 )TiO 4 nano crystals with regular morphology were prepared at 1000 o C in NaCl-KCl salt system. The synthesized temperature of single phase (Zr 0.8 ,Sn 0.2 )TiO 4 is lower and the crystal growth is more complete compared with the hydrothermal-solid state method. The rod-like crystalline grain are evenly distributed with a diameter of about 50–60 nm and can be used as start materials for preparing ZST textured ceramics. The (Zr 0.8 ,Sn 0.2 )TiO 4 nano crystal has a certain photocatalytic effect and good UV shielding performance. (Zr 0.8 ,Sn 0.2 )TiO 4 nano powders were prepared by hydrothermal-molten salt method. Synthetic nano powder can be used as the starting material for preparing ZST textured ceramics. The synthesized powder has a certain degree of photocatalysis and good UV shielding performance. The synthesized powder is rod-like crystal grains, uniformly distributed, with a diameter of about 50–60 nm. | Preparation and characterization of (Zr0.8,Sn0.2)TiO4 nano crystals by hydrothermal-molten salt method | 10.1007/s10971-021-05581-3 |
2021-08-01 | Studies on phase transformations in Fe-11Al-5Mn-1C (Alloy 1) and Fe-11Al-10Mn-1C (Alloy 2) ferritic low-density steels were carried out using differential thermal analysis (DTA) and dilatometry (all compositions in wt.%). An appreciable difference was observed between the phase transformation temperatures predicted by the ThermoCalc software and the experimental values. The ferrite + kappa carbide → austenite phase transformation started around 1017 °C for Alloy 1 and 960 °C for Alloy 2. The dissolution of carbides was completed around 1115 °C and 1050 °C for Alloy 1 and Alloy 2, respectively. Studies on water quenched alloys were carried out to confirm the phase transformation temperatures. Both the alloys were hot rolled at 1000 °C. The rolled alloys exhibited high yield and tensile strength due to the presence of a large volume fraction of kappa carbides. After hot rolling, Alloy 2 exhibited higher ductility than Alloy 1. This is attributed to the presence of a higher volume fraction of metastable austenite in Alloy 2. Reasons for the presence of metastable austenite are discussed. Fracture surfaces of the tensile samples revealed crack initiation and propagation along ferrite-kappa carbide interfaces. | Phase Transformation and Hot Working Studies on High-Al Fe-Al-Mn-C Ferritic Low-Density Steels | 10.1007/s11665-021-05857-3 |
2021-08-01 | The influence of the underlying nucleation layer on the properties of semipolar $$(11{\bar{2}}2)$$ ( 11 2 ¯ 2 ) GaN grown on m -plane sapphire by metalorganic vapor-phase epitaxy has been investigated. $$(11{\bar{2}}2)$$ ( 11 2 ¯ 2 ) GaN epilayers of ~ 1 μ m thickness were grown using four different initiating sequences: low-temperature AlN and GaN, and high-temperature AlN buffer layers, and directly (high-temperature GaN). The choice of nucleation layer had a pronounced effect on the surface morphology and crystal quality of the overlying GaN epilayer. In comparison, direct growth of $$(11{\bar{2}}2)$$ ( 11 2 ¯ 2 ) GaN without any buffer layer provided the best crystal quality with a rocking-curve $$\omega $$ ω full-width at half-maximum (FWHM) value of 720 arcsec along the $$[11{\bar{2}}{\bar{3}}]$$ [ 11 2 ¯ 3 ¯ ] direction and relatively enhanced near-band-edge photoluminescence emission, thus showing this direct growth process to be a simple route for synthesis of semipolar $$(11{\bar{2}}2)$$ ( 11 2 ¯ 2 ) GaN layers. | Influence of Nucleation Layers on MOVPE Growth of Semipolar (
$$11{\bar{2}}2$$
11
2
¯
2
) GaN on m-Plane Sapphire | 10.1007/s11664-021-08969-7 |
2021-08-01 | Abstract Wood is an increasingly important material in the sustainable transition of societies worldwide. The performance of wood in structures is intimately tied to the presence of moisture in the material, which directly affects important characteristics such as dimensions and mechanical properties, and indirectly its susceptibility to fungal decomposition. By chemical modification, the durability of wood in outdoor environments can be improved by reducing the amount of moisture present. In this study, we refined a well-known chemical modification with acetic anhydride and showed how the spatial distribution of the modification of Norway spruce ( Picea abies (L.) Karst.) could be controlled with the aim of altering the wood-water interactions differently in different parts of the wood structure. By controlling the reaction conditions of the acetylation it was possible to acetylate only the cell wall-lumen interface, or uniformly modify the whole cell wall to different degrees. The spatial distribution of the acetylation was visualised by confocal Raman microspectroscopy. The results showed that by this targeted acetylation procedure it was possible to independently alter the wood-water interactions in and outside of cell walls. The cell wall-lumen interface modification altered the interaction between the wood and the water in cell lumina without affecting the interaction with water in cell walls while the uniform modification affected both. This opens up a novel path for studying wood-water interactions in very moist environments and how moisture distribution within the wood affects its susceptibility towards fungal decomposition. Graphic abstract | Targeted acetylation of wood: a tool for tuning wood-water interactions | 10.1007/s10570-021-04033-z |
2021-08-01 | Near-neutral bleaching of cotton fabrics at low temperature is of great importance for saving energy and ecological friendliness in textile industry. In this work, glycerol triacetate (GT) was investigated as an activator of hydrogen peroxide (H 2 O 2 ) for low temperature bleaching of cotton knitted fabrics, and satisfactory whiteness was obtained. The bleaching properties of H 2 O 2 /GT system for cotton was assessed by the CIE whiteness index (WI), H 2 O 2 decomposition rate, concentration of generated peracetic acid and bursting strength. Possible factors affecting the properties of cotton bleached by H 2 O 2 /GT bleaching system were discussed in detail. At 60 °C, adding only 10 mmol/L GT to the hydrogen peroxide solution (60 mmol/L) to bleach cotton knitted fabrics for 60 min, the WI was significantly increased from 52.09 to 68.92. By using benzenepentacarboxylic acid as a fluorescent probe for hydroxyl radical (HO·) detection, it was found that GT could clearly promote HO· generation and its concentration closely related to the WI of cotton fabric. Furthermore, the bleaching mechanism of H 2 O 2 /GT system was proposed by exploring the relationship between WI and HO· concentration. GT as a bleach activator has more economical benefits and better water solubility than tetraacetylethylenediamine. The H 2 O 2 /GT system may provide a cost-effective and environmentally friendly bleaching approach of cotton as alternative to conventional alkaline high-temperature bleaching. | An eco-friendly approach to low-temperature and near-neutral bleaching of cotton knitted fabrics using glycerol triacetate as an activator | 10.1007/s10570-021-04030-2 |
2021-08-01 | Abstract Viscous bitumen for highway use, which matches all the physicomechanical properties of BND 60/90 bitumen (in other words, those required by the standard for bitumen), may be produced by modifying the organic component of hydrogenated coal with sulfur. The new bitumen may be used as a road surface operating at mean monthly temperatures between –10 and –20°C. On adding sulfur, the content of monocyclic, bicyclic, and condensed aromatic hydrocarbons in BND 60/90 bitumen is decreased, while the content of asphaltenes and tars is increased. That may be explained by the reaction of sulfur with aromatic compounds. | Bitumen Production from Shubarkol Coal (Kazakhstan) | 10.3103/S1068364X21080044 |
2021-08-01 | The partitioning of nitrogen atoms and its effect on the retained austenite content (RAC) during quenching and partitioning (Q&P) process were investigated by dilatometry, X-ray diffraction, and field emission transmission electron microscopy with energy-dispersive spectrometer mapping in a 00Cr13Mn8N steel. Nitrogen partitioning by diffusion of N atoms from martensite to austenite occurred at 400 °C after quenching. N atoms are enriched in austenite after partitioning, and the stability of these N-rich austenite is improved and retained at room temperature during subsequent cooling. The different quenching temperatures (QTs) result in different phase fractions after partitioning. With the increase in QT, RAC first increases and then decreases, and the maximum RAC is 28.5 vol.% after quenching at 80 °C. A mathematical model was developed to rapidly and accurately characterize the phase fraction in Q&P process based on the relative length change of the samples partitioned after quenching at different QTs. | Partitioning of nitrogen atoms and its effect on retained austenite content in an ultra-low-carbon Cr–Mn–N stainless steel | 10.1007/s42243-021-00560-y |
2021-08-01 | An innovative method for utilizing synthetic calcium fluoride (CaF 2 ), recovered from fluoride-containing semiconductor wastewater, and waste sulfuric acid (H 2 SO 4 ) to produce hydrofluoric acid (HF) was investigated. The research was set to study the low-temperature production of HF via reaction of synthetic CaF 2 and waste H 2 SO 4 . The impact of four factors, including H 2 SO 4 concentration, total volume (H 2 SO 4 + H 2 O)/CaF 2 ratio, drying temperature of synthetic CaF 2 , and reaction carried out under different temperature, on HF productivity was investigated in this study. HF yield increased with increasing H 2 SO 4 concentration and total volume/CaF 2 ratio under room temperature. Generally, reactions carried out under low-temperature (< 100 °C) had a positive impact on HF yield. The higher temperature led to an increase in absorbed-HF but a decrease in total-HF. The reaction of commercial CaF 2 and 70% H 2 SO 4 had a higher absorbed-HF yield of 61.7% than synthetic CaF 2 and 70% waste H 2 SO 4 , which had a yield of 36%. This was due to the higher purity of the commercial CaF 2 and fewer interference ions in H 2 SO 4 . HF productivity was lowered by CaSO 4 , which hindered the reaction of reactants and also the generation of fluorosulfuric acid. | Recycle of synthetic calcium fluoride and waste sulfuric acid to produce electronic grade hydrofluoric acid | 10.1007/s11356-020-09867-x |
2021-08-01 | The impact energy prediction model of low carbon steel was investigated based on industrial data. A three-layer neural network, extreme learning machine, and deep neural network were compared with different activation functions, structure parameters, and training functions. Bayesian optimization was used to determine the optimal hyper-parameters of the deep neural network. The model with the best performance was applied to investigate the importance of process parameter variables on the impact energy of low carbon steel. The results show that the deep neural network obtains better prediction results than those of a shallow neural network because of the multiple hidden layers improving the learning ability of the model. Among the models, the Bayesian optimization deep neural network achieves the highest correlation coefficient of 0.9536, the lowest mean absolute relative error of 0.0843, and the lowest root mean square error of 17.34 J for predicting the impact energy of low carbon steel. Among the variables, the main factors affecting the impact energy of low carbon steel with a final thickness of 7.5 mm are the thickness of the original slab, the thickness of intermediate slab, and the rough rolling exit temperature from the specific hot rolling production line. | Prediction of the Charpy V-notch impact energy of low carbon steel using a shallow neural network and deep learning | 10.1007/s12613-020-2168-z |
2021-08-01 | The low velocity impact response of the epoxy composite materials, which were reinforced with various hybrid contents, such as plain pure or hybrid fabrics (carbon, aramid and glass fibers and copper wires) and filler mixtures into the epoxy matrix (aramid powder, potatoes starch, barium ferrite and carbon black) was investigated using a drop weight impact machine. The aim of this study was to characterize and assess the effects of fiber orientation at various angles and filler mixtures into epoxy matrix on the impact response. All the tests were carried out at constant impact energy, namely 90.629 J. Results indicated that the fiber orientation at various angles has a positive effect on impact response, mainly in the case of aramid fabric reinforced composites. In terms of influence of fillers addition into matrix, it was obtained an improvement on the impact response of hybrid fabric reinforced composite as compared to the pure fabric reinforced composites. | Influence of Fiber Orientation and Fillers on Low Velocity Impact Response of the Fabric Reinforced Epoxy Composites | 10.1007/s10443-021-09910-1 |
2021-08-01 | In this study, we have designed and synthesized a low-bandgap polymer, DPP-Qx, using quinoxaline (Qx), a non-alkylated weak acceptor, with diketopyrrolopyrrole (DPP) as an electron donor. The incorporation of Qx into DPP leads to the highest occupied molecular orbital level at −5.1 eV with a narrow optical bandgap (1.25 eV). The synthesized polymer is utilized in photovoltaics, and the photovoltaic properties are studied. This DPP-Qx with fullerene acceptors in polymer solar cells (PSCs) exhibits efficiency of 3.26%. Moreover, a minimum energy loss of 0.57 eV along with high extended external quantum efficiency is achieved with the DPP-Qx electron donor. The thermal, electrical and optical properties, energy levels and hole mobility of the synthesized polymer are studied and discussed. | Low-Bandgap DPP-Based Quinoxaline with Extended EQE and Low Energy Loss for Efficient Polymer Solar Cells | 10.1007/s11664-021-08868-x |
2021-08-01 | In Latin America, default assumptions and borrowed templates and methodologies are often used in energy modeling, resulting in models that might not represent their cultural context and leading to policies awkwardly fit to local practices. Policy-driving low-income housing studies in Mexico, for example, activated both heating and cooling in energy models even though less than 5% of the homes in the country have heating systems. This paper illustrates the importance of modeling local sociocultural habits and practices, and how this can affect design outcomes. Here, we modeled low-income housing representative of typical residences in two desert climates—Hermosillo, Mexico, and Copiapo, Chile—using EnergyPlus. Settings representing local practices in each region were tested against default values, including occupancy settings, regional construction systems, and importantly, HVAC settings related to partial conditioning. Their impacts were measured via variation in energy use, comfort conditions, and the payback period of design upgrades. Results demonstrated how certain assumptions can have a high “design significance”, a term we propose for inputs that completely change optimal design decisions, as well as the importance of considering thermal comfort in such decisions. Including partial conditioning, for example, resulted in at least double the payback period and discomfort degrees for design upgrades in 16 of 24 instances. | The impact of cultural assumptions on simulated energy, comfort, and investment returns of design decisions in two desert climates | 10.1007/s12273-020-0718-y |
2021-08-01 | Abstract The influence of structural inhomogeneity on a superconducting gap near d -wave nodes is co-nsidered for optimally doped YBa 2 Cu 3 O 6.92 HTSCs. To this aim, specific heat in the temperature range of T = 2‒10 K at magnetic fields H = 0–9 T is analyzed for a series of fine-crystalline samples with different degrees of controlled structural disorder. Information about specific features of the superconducting gap near d -wave nodes in structurally disordered samples is obtained. It is shown that d -wave nodes (typical of an ideal crystal structure) change under the influence of structural disorder with the formation of small Fermi arcs, which are not covered by the superconducting gap, in the vicinity of the nodal point at T $$ \ll $$ T c . Note that the gap is retained at T ≤ T c in other directions of the Brillouin zone and coexists with Fermi arcs. This transformation is accompanied by an increase in the nodal slope, a decrease in the Volovik effect, and creation of the metal-type linear term γ(0) T in the temperature dependence of the specific heat, which should not exist for superconductors with an ideal crystal structure; its nature has not yet been established. | Formation of Fermi Arcs at T
$$ \ll $$
Tc in the Vicinity of d-Wave Nodes of Structurally Inhomogeneous YBa2Cu3O6.92 HTSCs | 10.1134/S1063783421080187 |
2021-08-01 | Regucalcin (RGN) is a calcium-binding protein mainly expressed in the liver. It functions in regulating activities of several calcium-dependent enzymes related to energy metabolism, antioxidant mechanisms, and apoptotic pathways. Previous proteomics analyses revealed downregulation of regucalcin in milkfish livers when acclimated to low temperature (18 °C) from normal temperature (28 °C). This study first identified the full-length sequence of milkfish regucalcin from the livers with high similarity in the protein structure and calcium-binding function compared to the regucalcin of other animals. The mRNA and protein expression of regucalcin in the livers of fresh water (FW)– and seawater (SW)-acclimated milkfish under hypothermal acclimation were further analyzed. In FW milkfish, upregulation of regucalcin was found in mRNA and protein levels from 2 to 4 days, respectively, to 1 week after transfer to 18 °C for the two. However, in SW milkfish, upregulation of regucalcin occurred quickly and returned to the basal levels in 1 (mRNA expression) or 2 days (protein expression) up until 1 week after transfer. These results suggested potential roles of regucalcin in maintaining calcium homeostasis and its correlation to differential physiological responses in the livers of milkfish when they were acclimated to FW and SW. | Hypothermal effects on expression of regucalcin, a calcium-binding protein, in the livers of seawater- and fresh water–acclimated milkfish, Chanos chanos | 10.1007/s10695-021-00960-7 |
2021-08-01 | Abstract Some results of studying the unoccupied electron states and the formation of a boundary potential barrier during the thermal vacuum deposition of ultrathin 4-quaterphenyl oligophenyl films onto the surfaces of CdS and oxidized silicon were presented. Using X-ray photoelectron spectroscopy (XPS), the atomic Cd and S concentrations were established to be the same on the surface of a 75-nm CdS layer formed by atomic layer deposition (ALD). The electron characteristics of 4-quaterpheyn films with a thickness of up to 8 nm were studied in the process of their deposition onto the surface of a formed CdS layer and the surface of oxidized silicon by total current spectroscopy (TCS) within an energy range from 5 to 20 eV above E F . The energy positions of major maxima in the fine structure of the total current spectra (FSTCS) of 4-quaterphenyl films were established. The positions of maxima were reproducible, when the two selected materials of substrates were used. A slight decrease in the work function from 4.2 to 4.1 eV during the thermal deposition of 4-quaterpheynl onto the CdS surface was established. The work function was revealed to grow from 4.2 to 4.5 eV, when a 4-quaterphenyl film was deposited onto the surface of oxidized silicon. Some possible mechanisms of physicochemical interaction between the 4-quaterphenyl film and the surfaces of the studied substrates that lead to different work function values observed on these substrates were discussed. | Unoccupied Electron States of Ultrathin Quaterphenyl Films on the Surfaces of Layered CdS and Oxidized Silicon | 10.1134/S1063783421080138 |
2021-08-01 | This study aims to explore the feasibility of biochar as a carrier to improve the simultaneous removal of nitrogen and phosphorus in biological aerated filters (BAFs) for treating low C/N digested swine wastewater (DSW). Two similar BAFs (BAF-A with hydrophobic polypropylene resin as fillers and BAF-B with bamboo biochar as carrier) were developed for DSW treatment. Results showed that the NH 4 + -N, TN, and TP removal performances in BAF-B were higher than those in BAF-A. Carrier type had an obvious influence on the structures and diversity of the microbial population. The biochar carrier in BAF-B was conducive to the enrichment of the functional microorganisms and the increase of microbial diversity under high NH 4 + -N conditions. Microbial analysis showed that the genera Rhodanobacter (10.64%), JGI_0001001-h003 (14.24%), RBG-13–54-9 (8.87%), Chujaibacter (11.27%), and Ottowia were the predominant populations involved in nitrogen and phosphorus removal in the later stage of phase III in BAF-B. BAF with biochar as carrier was highly promising for TN and TP removal in low C/N and high NH 4 + -N DSW treatment. | Performances of simultaneous enhanced removal of nitrogen and phosphorus via biological aerated filter with biochar as fillers under low dissolved oxygen for digested swine wastewater treatment | 10.1007/s00449-021-02557-z |
2021-08-01 | This paper extensively studies the spacer technology, including low- k /high- k , single/dual dielectrics on the device performances focusing on the leakage current. The tactical use of a spacer, introduction of a low bandgap material as a pocket on the source side along with the incorporation of gate dielectrics helped in improving the switching ratio effectively. A systematic comparison is made in between the conventional symmetrical single low- k spacer 3D FinFET and the proposed optimized 3D FinFET. Various device architectures are evaluated by showing significant improvements in on current (I on ) and off state leakage (I off ), leading to a high switching ratio (I on /I off ) and the subthreshold slope (SS). An I on /I off of value 1 × 10 6 indicates sufficient electrostatics to control over the channel, and our study results in ~8 time of this value. These parameters are obtained after the appropriate selection of low- k & high- k spacer length on both sides of the source and drain. The use of SiGe material near the source side to modulate carrier mobility and incorporating high- k gate dielectric to suppress leakage. | Improvising the Switching Ratio through Low-k / High-k Spacer and Dielectric Gate Stack in 3D FinFET - a Simulation Perspective | 10.1007/s12633-020-00618-8 |
2021-08-01 | Abstract Secondary and tertiary amines of the acetylene series of various structures (14 compounds) were synthesized based on propargylamine. The possibility of a significant inhibition with these substances of low-carbon steel corrosion in hot solutions of hydrochloric acid has been established. The protective effect of acetylenic amines rises with an increase in their content in an aggressive environment and with an increase in its temperature. The maximum protection effect is provided by tertiary amines containing 2,3-epoxypropyl or 2,3-epithiopropyl as a substituent. The presence of chemically active epoxy and epithio groups in the structure of these acetylenic compounds promotes the stimulation of their polymerization on the steel surface through the opening of C≡C bonds, which leads to the rapid formation of a protective polymer film on it. | Substituted Propargylamines—Acid Corrosion Inhibitors for Steel in Petroleum Industry | 10.1134/S1070427221080103 |
2021-08-01 | Abstract Some types of the slot input of high energy into cylindrical and rectangular cavities are considered. The energy input through slot waveguiding apertures located at the central circle of the cavity is selected and optimized. The standing wave ratio of the system is determined. The change in the electrical field energy in the cavity, when the position of the slot waveguide is shifted, is simulated. The optimum (best for processing with microwave discharge plasma) positions of the objects and waveguide slots as well as critical positions (choosing which can put the oscillator out of action) are shown. The increase in the field density between two metallic objects is calculated. The results demonstrating the inacceptable way of the slot input of energy for solving some types of problems related to processing of complex surfaces with the microwave discharge are obtained. | Study of Distribution of the Electric Field in a Plasma Chamber with Slot Input of Microwave Energy | 10.1134/S1063780X2108002X |
2021-08-01 | Reliable data on the effects of chronic prenatal exposure to low dose (LD) of ionizing radiation in humans are missing. There are concerns about adverse long-term effects that may persist throughout postnatal life of the offspring. Due to their slow cell cycle kinetics and life-long residence time in the organism, mesenchymal stem cells (MSCs) are more susceptible to low level genotoxic stress caused by extrinsic multiple LD events. The aim of this study was to investigate the effect of chronic, prenatal LD gamma irradiation to the biology of MSCs later in life. C3H mice were exposed in utero to chronic prenatal irradiation of 10 mGy/day over a period of 3 weeks. Two years later, MSCs were isolated from the bone marrow and analyzed in vitro for their radiosensitivity, for cellular senescence and for DNA double-strand break recognition after a second acute gamma-irradiation. In addition to these cellular assays, changes in protein expression were measured using HPLC–MS/MS and dysregulated molecular signaling pathways identified using bioinformatics. We observed radiation-induced proteomic changes in MSCs from the offspring of in utero irradiated mice (leading to ~ 9.4% of all detected proteins being either up- or downregulated) as compared to non-irradiated controls. The proteomic changes map to regulation pathways involved in the extracellular matrix, the response to oxidative stress, and the Wnt signaling pathway. In addition, chronic prenatal LD irradiation lead to an increased rate of in vitro radiation-induced senescence later in life and to an increased number of residual DNA double-strand breaks after 4 Gy irradiation, indicating a remarkable interaction of in vivo radiation in combination with a second acute dose of in vitro radiation. This study provides the first insight into a molecular mechanism of persistent MSC damage response by ionizing radiation exposure during prenatal time and will help to predict therapeutic safety and efficacy with respect to a clinical application of stem cells. | In vitro cellular and proteome assays identify Wnt pathway and CDKN2A-regulated senescence affected in mesenchymal stem cells from mice after a chronic LD gamma irradiation in utero | 10.1007/s00411-021-00925-7 |
2021-08-01 | This article discusses the absence of methods for measuring low-frequency (LF) fluctuation processes at high temperatures and proposes an original bridge method for measuring the spectra of LF current fluctuations in the tungsten filaments of electric lamps in the controlled temperature range 300–2700 K. The application of the bridge measurement circuit reduces the influence of degradation processes in the filament and the power source’s own noise on the measurement results by several orders of magnitude. A spectral analysis of LF current fluctuations is performed in the frequency range 1.5·10 –5 –5·10 –1 Hz using an automated unit based on a personal computer under the control of specially developed software. | Bridge Method for Studying the Spectra of Current Fluctuations in Tungsten Filaments in the Frequency Range 1.5·10–5–5·10–1 Hz | 10.1007/s11018-021-01942-0 |
2021-08-01 | Mosques within the professional environments such as universities, banks and shopping malls possess different features that from the public mosques. These mosques are of relatively smaller size, less airy, populated for a shorter duration of the day and the visitors with more formal dressing. All these factors contribute to an increased activity of Volatile Organic Compounds (VOCs) generated by the visitors. Improper drying of the wet feet after ablution and/or prolonged wearing of socks, while being in professional environments, further worsens the situation. A prolonged activity of these VOCs in confined environments is not only unpleasant but also poses certain health issues. This study aims at identification of the need to control this activity within an acceptable limit by deploying a low-cost smart computational configuration of sensor array. The configuration parameters depend on a number of factors such as mosque space, ventilation, air conditioning and the quantity and quality of VOCs generated on average. Pertinent VOC data monitoring, computing and averaging across a network is done in real-time using mobile sensing stations. A proof of concept-based technical feasibility on the adoption of a control strategy is conducted by establishing an acceptable threshold level for the VOCs activity in varying conditions. As the sensitivity of the sensor and the lifespan & proliferation of the VOCs are affected by the humidity, temperature and the air circulation, these factors are closely monitored. Mosque being a sacred place, all these experiments are constrained to be conducted in a controlled manner without any disturbance whatsoever to the environment, visitors and the religious activities being performed. | Identification and control of the volatile organic compounds activity in confined environments (Mosques) | 10.1007/s11227-020-03599-y |
2021-08-01 | The ATP6ap2 (Pro)renin receptor protein associates with H + -ATPases which regulate organellar, cellular, and systemic acid–base homeostasis. In the kidney, ATP6ap2 colocalizes with H + -ATPases in various cell types including the cells of the proximal tubule. There, H + -ATPases are involved in receptor-mediated endocytosis of low molecular weight proteins via the megalin/cubilin receptors. To study ATP6ap2 function in the proximal tubule, we used an inducible shRNA Atp6ap2 knockdown rat model (Kd) and an inducible kidney-specific Atp6ap2 knockout mouse model. Both animal lines showed higher proteinuria with elevated albumin, vitamin D binding protein, and procathepsin B in urine. Endocytosis of an injected fluid-phase marker (FITC- dextran, 10 kDa) was normal whereas processing of recombinant transferrin, a marker for receptor-mediated endocytosis, to lysosomes was delayed. While megalin and cubilin expression was unchanged, abundance of several subunits of the H + -ATPase involved in receptor-mediated endocytosis was reduced. Lysosomal integrity and H + -ATPase function are associated with mTOR signaling. In ATP6ap2, KO mice mTOR and phospho-mTOR appeared normal but increased abundance of the LC3-B subunit of the autophagosome was observed suggesting a more generalized impairment of lysosomal function in the absence of ATP6ap2. Hence, our data suggests a role for ATP6ap2 for proximal tubule function in the kidney with a defect in receptor-mediated endocytosis in mice and rats. | The (pro)renin receptor (ATP6ap2) facilitates receptor-mediated endocytosis and lysosomal function in the renal proximal tubule | 10.1007/s00424-021-02598-z |
2021-08-01 | The biaxial accumulative plasticity and the biaxial non-proportional low-cycle fatigue crack growth behavior of a hull structure subjected to biaxial non-proportional low-cycle fatigue loading under phase differences of approximately 45°, 90°, and 180° were investigated in this study. Biaxial non-proportional low-cycle fatigue crack propagation tests were conducted on cruciform Q235 steel specimens containing an inclined crack to validate the analysis. The fracture morphologies and the crack propagation angles of the cruciform specimens containing an inclined crack under different phase differences were examined. Numerical simulations were conducted to simulate the stress–strain field and the accumulative plasticity. The effects of the different phase differences, biaxiality ratios, and stress ratios on the biaxial non-proportional low-cycle fatigue crack growth rates of the cruciform Q235 steel specimens with an inclined crack were analyzed. The obtained results provide a basis for the accurate evaluation of the biaxial non-proportional low-cycle fatigue crack growth fracture behavior of a hull’s cracked plate. | Analysis of Biaxial Non-Proportional Low-Cycle Fatigue Crack Propagation Behavior of Hull Plate with an Inclined Crack Based on Accumulative Plasticity | 10.1007/s11668-021-01179-7 |
2021-08-01 | This paper presents an imprecise predictive inference method for accelerated life testing. The method is largely nonparametric, with a basic parametric function to link different stress levels. The log-rank test is used to provide imprecision for the link function parameter, which in turn provides robustness in the resulting lower and upper survival functions for a future observation at the normal stress level. An application using data from the literature is presented, and simulations show the performance and robustness of the method. In case of model misspecification, robustness may be achieved at the price of large imprecision, which would emphasize the need for more data or further model assumptions. | Imprecise inference based on the log-rank test for accelerated life testing | 10.1007/s00184-021-00807-4 |
2021-08-01 | Objective To correct for image distortions produced by standard Fourier reconstruction techniques on low field permanent magnet MRI systems with strong $${B}_{0}$$ B 0 inhomogeneity and gradient field nonlinearities. Materials and methods Conventional image distortion correction algorithms require accurate $${\Delta B}_{0}$$ Δ B 0 maps which are not possible to acquire directly when the $${B}_{0}$$ B 0 inhomogeneities also produce significant image distortions. Here we use a readout gradient time-shift in a TSE sequence to encode the $${B}_{0}$$ B 0 field inhomogeneities in the k-space signals. Using a non-shifted and a shifted acquisition as input, $$\Delta {B}_{0}$$ Δ B 0 maps and images were reconstructed in an iterative manner. In each iteration, $$\Delta {B}_{0}$$ Δ B 0 maps were reconstructed from the phase difference using Tikhonov regularization, while images were reconstructed using either conjugate phase reconstruction (CPR) or model-based (MB) image reconstruction, taking the reconstructed field map into account. MB reconstructions were, furthermore, combined with compressed sensing (CS) to show the flexibility of this approach towards undersampling. These methods were compared to the standard fast Fourier transform (FFT) image reconstruction approach in simulations and measurements. Distortions due to gradient nonlinearities were corrected in CPR and MB using simulated gradient maps. Results Simulation results show that for moderate field inhomogeneities and gradient nonlinearities, $$\Delta {B}_{0}$$ Δ B 0 maps and images reconstructed using iterative CPR result in comparable quality to that for iterative MB reconstructions. However, for stronger inhomogeneities, iterative MB reconstruction outperforms iterative CPR in terms of signal intensity correction. Combining MB with CS, similar image and $$\Delta {B}_{0}$$ Δ B 0 map quality can be obtained without a scan time penalty. These findings were confirmed by experimental results. Discussion In case of $${B}_{0}$$ B 0 inhomogeneities in the order of kHz, iterative MB reconstructions can help to improve both image quality and $$\Delta {B}_{0}$$ Δ B 0 map estimation. | Image distortion correction for MRI in low field permanent magnet systems with strong B0 inhomogeneity and gradient field nonlinearities | 10.1007/s10334-021-00907-2 |
2021-08-01 | An in situ relationship between the deformation behavior characteristics and the spatial and temporal evolution of deformation field distributions is studied in flat samples of technically pure A7 aluminum under uniaxial tension. Using a VIC-3D digital optical system, the features of the deformation field evolution on the sample surfaces at a macroscopic scale level are revealed. It is found out that in the transient section of the stress – strain curve in the patterns of distributions of longitudinal strains ε YY , in addition to the macrohomogenous deformation on the surface of the gaging section of the sample, randomly distributed centers of tension and compression are observed to form. The presence of a transient section from elastic to plastic deformation indicates a low-stability state of the material. In the case where the stresses become higher than the elastic limit during the transition to the stage of plastic deformation, small foci of deformation merge into larger areas in the distribution patterns of the longitudinal relative strains on the sample surface. The transition from one stage to another occurs through the low-stability state of the system and is manifested, in addition to other factors, in a changed deformation field distribution on the surface of the sample under tension. | Relationships Between Characteristics of Deformation Behavior and Evolution of Deformation Fields in Aluminum Under Uniaxial Tension | 10.1007/s11182-021-02388-1 |
2021-08-01 | Abstract The trends in river runoff during the winter lower water period in the Ural River basin have been analyzed in this work. The long-term dynamics of the runoff parameters has been studied. Concurrently, consideration has been given to the phases with a different river water content. It was found that the water regime of the rivers in the study basin is characterized by a stable trend of a decreasing share of the spring runoff and an increasing share of the winter runoff. The growth of the share of winter runoff is caused by an increase in the frequency and duration of positive temperature anomalies and the share of basic (underground) river feeding. Comparison of the annual runoff and 30-day values of the minimum runoff in the winter period illustrates a certain interdependence in the changes of their values. In spite of the general trend of the increasing winter low water discharges, certain differences have been revealed for the rivers of the basin studied due to the heterogeneous conditions under which the runoff is formed. The regional features of the formation of the winter low water runoff confirm the different dates for occurrence of the maximum (complete) depletion of the river runoff. The significant increase in the water content of the rivers in winter affects the decrease in the variability of daily discharges, which is consistent with the previously established trend of decreasing interannual variability of the river runoff in the basin of the Ural River. The increase in the winter low water runoff is of great practical importance, because the runoff value for a given period is the limiting factor that determines the guaranteed and sustainable water consumption. Accordingly, the current trends in the change in the water regime of the rivers of the Urals basin must be taken into consideration when determining the regulations and norms for the use of water resources in the steppe zone. | Changes in River Runoff during Winter Low Water Periods in the Basin of the Ural River | 10.1134/S1028334X2108016X |
2021-08-01 | The effects of high pressure (100–500 MPa) and heated (80 °C, 25 min) combinations on gel properties, rheological characteristic and water distribution of pork batters were investigated. Compared to the only-heat, the cooking yield, a * value, hardness, cohesiveness, and chewiness of cooked pork batters treated less than 300 MPa were significantly increased ( P < 0.05), meanwhile, the b * value was significantly decreased ( P < 0.05). Opposite, the color and cooking yield were not significant different ( P > 0.05) when over 300 MPa, except the L * value. At 300 MPa, the cooking yield, hardness, chewiness, and G′ value at 80 °C of pork batter were the highest. The initial relaxation time of T 21 was decreased significantly ( P < 0.05), and the peak ration of P 21 was increased significantly ( P < 0.05) when treated at 200 and 300 MPa, that indicated the water was bound tightly and the ratio of immobilized water was increased. Overall, 300 MPa treatment and thermal combinations could improve the gel properties of pork batters. | Effects of high pressure and thermal combinations on gel properties and water distribution of pork batters | 10.1007/s13197-021-05051-2 |
2021-08-01 | Abstract The processes of structure formation during plasma hardening of samples made of 65G grade low-alloy structural steel have been studied using optical metallography. It is shown that the structure formation during quenching after exposure to a highly concentrated energy flux obeys general structure formation features described by the iron–carbon phase diagram. The depth of the hardened structural zones in occurring under plasma quenching depends on the parameters of heating and cooling and is determined by the mechanisms and kinetics of α → γ phase transformations under nonequilibrium conditions. By changing the heating parameters (heating rate, holding time), one can control the level of homogeneity and the size of austenite grains at the beginning of the γ → α transformation, and, by changing the cooling rate, one can control the dispersion level of martensite in the reverse γ → α transformation, therefore, the properties of steel. The study results show the fact that in order to obtain the maximum possible hardening, it is necessary to carry out a preliminary heat treatment, which could provide fine austenite grains by the beginning of the α → γ transformation with a more stable structural state of the initial phase in combination with the crystal structure defects. | Structure Formation under Plasma-Assisted Hardening of Thin-Walled Low-Weight Parts | 10.3103/S0967091221080064 |
2021-08-01 | A phase frequency detector (PFD) with a very low dead zone is proposed which is based on a configuration adaptable to both CMOS or carbon nano-tube transistors (CNTFETs). In the first step the proposed configuration is designed using CMOS transistors, and then CNTFETs are substituted to improve the speed and reduce the propagation delay. The proposed PFD in addition to very low dead zone, has low power consumption and high frequency range of operation, which are achieved as a result of the elimination of the reset path. The simulation results based on 32 nm technology for CNTFET and 180 nm technology for CMOS, illustrate that CNTFET-based proposed circuit dissipates 2 µW and has frequency of operation up to 30 GHz, and the dead zone equal to 1 ps. Compared to the conventional PFD based on CMOS technology, its dead zone and power consumption are lower. In addition, the effects of blocks’ parameters including the phase detector, which affect the operation of the phase locked loop, or delay locked loop, are systematically analyzed. | Low-power high-speed phase frequency detector based on carbon nano-tube field effect transistors | 10.1007/s10470-021-01845-8 |
2021-08-01 | Abstract The endangered and declining butterfly species Colias myrmidone is sensitive to land-use changes and vulnerable in its immature stages. The requirements for its larval habitats are still largely unknown, which hinders appropriate management in protected areas. We examined the relation between the larval development of C. myrmidone and environmental variables at a Natura 2000 site in Romania. Individuals that reached higher larval stages had a higher cover of litter as well as a lower cover of forbs around their host plants than individuals that died in early larval stages or as eggs. Surviving individuals had less other host plants in their surrounding and were found on larger host plants. Surviving individuals were found further away from the tip of their hosts than individuals that were lost due to grazing. The grazing regime is of particular importance to ensure the successful development of C. myrmidone from egg to higher larval stages. There seems to be a trade-off between positions at the tip of the shoot with palatable leaves and positions further down that protect against grazing. Especially sheep grazing may cause high direct mortality. The higher amount of litter around surviving larvae indicates a better survival when the grazing pressure is very low, but still present to keep the habitat open. However, occasional heavy grazing events may reduce the cover of forbs. Implications for insect conservation The designation of the investigated Natura 2000 site offers a great opportunity to implement the insights on larval development of C. myrmidone into a management plan, which can support low-intensity grazing regimes preferably with cattle. | Preserving Colias myrmidone in European cultural landscapes: requirements for the successful development from egg to higher larval stages at a Natura 2000 site in Romania | 10.1007/s10841-021-00332-9 |
2021-08-01 | In this study, the effect of external treatment conditions [i.e., heat treatment conditions, storage conditions, pH, and high-intensity ultrasound (HIU)] on the stability of low-density lipoprotein (LDL) in egg yolk plasma modified by phospholipase A 2 (PLA 2 ) was studied. Asymmetrical flow field-flow fractionation (AF4) coupled with ultraviolet–visible (UV/Vis), multiangle light scattering (MALS) and differential refractive index (dRI) detectors was employed for the analysis of LDL modified with PLA 2 . The AF4 results show that PLA 2 modification enhanced the stability of LDL in terms of heat treatment and −18 °C storage. However, the extent of aggregation of PLA 2 -modified egg yolk plasma with HIU treatment (400 W for 10 min) was larger than that of raw egg yolk plasma, and the stability decreased. Alkaline condition (i.e., pH 10) promoted the aggregation of egg yolk plasma regardless of modification with PLA 2 . The increased knowledge of how external factors studied in this work affect the stability of PLA 2 -modified LDL could increase the understanding and controlling of properties of the food made of the egg yolk. | Investigation on the stability of low‐density lipoproteins modified by phospholipase A2 using asymmetrical flow field‐flow fractionation | 10.1007/s11694-021-00918-6 |
2021-08-01 | This study aimed to investigate the effects of balneological outpatient treatment (hydrotherapy and peloidotherapy) on clinical status and serum cytokine levels in patients with chronic low back pain (CLBP). Seventy-four patients with CLBP who accepted to participate to the study were randomly divided into two groups. The study group was given ten sessions (in 2 weeks) of hydrotherapy, peloidotherapy, and home exercise, while the control group was given only home exercise. All patients were assessed before and at the end of therapy, at the 1st and 3rd months. The primary outcomes were pain intensity on the visual analog scale (VAS) (VAS-pain, VAS-rest, VAS-exercise) and Oswestry Disability Index (ODI). The secondary outcome measures included patient’s and physician’s global assessment (VAS-PGA), (VAS-DGA), finger-to-floor distance (FFD), modified Schober test, Short Form-36 (SF-36), and the use of analgesic drug. Venous blood samples were drawn from all patients before/1st day and after therapy/12th day to measure serum interleukin (IL)-6 and IL-10 levels. Significant improvement was observed in the study group in VAS-pain, VAS-rest, VAS-exercise, VAS-PGA, VAS-DGA, ODI, and SF-36 parameters after treatment and improvement maintained for 3 months. In the control group, significant improvement was observed in VAS-pain, VAS-exercise, VAS-PGA, VAS-DGA, and ODI scores on the 12th day and continued for 3 months. Decrease in pain, pain during rest and exercise, modified Schober test, VAS-PGA, VAS-DGA, ODI scores, and the increase in SF-36 pain and general health scores showed superiority in favor of the study group in all evaluations. There was a significant increase in IL-10 values from baseline at the end of treatment in the study group. The use of non-steroidal anti-inflammatory drug (NSAID) was significantly lower in the study group compared with the use of NSAID in the control group in the 3rd month. Balneological outpatient treatment improved clinical status in CLBP patients. Although no significant correlation was clearly determined between IL-10 levels and pain score, this effect might be related to the observed increase in the anti-inflammatory cytokine IL-10 levels that was observed only in the study group. | Effects of balneological outpatient treatment on clinical parameters and serum cytokine levels in patients with chronic low back pain: a single-blind randomized controlled trial | 10.1007/s00484-021-02109-w |
2021-08-01 | Ultrafiltration and Diafiltration processes are used to concentrate proteins present in defatted milk in order to manufacture milk protein concentrate (MPC) powders. Selective passage of the water-soluble components causes retention as well as concentration of colloidal milk components in these processes. Increase in calcium and casein contents decreases the stability of milk proteins present in ultrafiltered retentates and negatively influence properties of manufactured MPC powders. Homogenization, diafiltration and disodium phosphate induced changes in properties of low-protein MPC powders were targeted in this study. Applied treatments significantly ( P < 0.05) improved foaming and emulsification, solubility, viscosity, heat stability, dispersibility, specific surface area and buffer index of resultant MPC powders over control. Fresh, treated low-protein MPC powders showed significantly higher (< 0.05) solubility values over control sample, which remains higher even after 60 days of storage at 25 ± 1 °C. The rheological behaviour of reconstituted low-protein MPC solutions was also studied. It was best explained as Herschel–Bulkley rheological behaviour. Low-protein MPC powders with improved functional properties may find better use as a protein ingredient in different dairy and food applications. | Production and characterization of cow milk based low-protein milk protein concentrate (MPC) powders | 10.1007/s13197-020-04824-5 |
2021-08-01 | Recently, the technology has evolved towards artificial intelligence world which include IoT (Internet of Things) and IoE (Internet of Everything) as communication between machines or between devices is possible. The development of these systems today requires electronic components capable of generating higher power and frequency levels, which is why new technologies have emerged to meet these needs, GaN HEMT technology. It has attracted a lot of attention for microwave power and high temperature applications. More recently, this technology has become a great interest to the international scientific community for the realization of low noise amplifiers which are the main components of wireless communication systems. In this paper, we modeled an LNA amplifier based on HEMT GaN transistors. This amplifier is unconditionally stable in the X-band (8–12) GHz with a gain of 38 dB, a noise factor does not exceed 2.4 dB and lower input and output reflection coefficients (S11, S22). at -14 dB and − 8 dB respectively. The designed amplifier can be integrated into radar systems, space communications systems and civilian-military radiolocation systems. | Design and Optimization of LNA Amplifier Based on HEMT GaN for X-Band Wireless-Communication and IoT Applications | 10.1007/s12633-020-00626-8 |
2021-08-01 | The Belt and Road Initiative (BRI) has promoted the deployment of renewable energy to achieve sustainability. It is essential to reveal the influence of renewable energy on low-carbon economic development. The share of renewable energy consumption (SREC) is taken as the core explanatory variable in this paper, and its impacts on carbon emission intensity (CEI) and economic growth are investigated from the spatial-temporal perspective. First, the panel Granger causality test is applied for revealing the causal links among SREC, CEI, and economic growth during 1999–2017. Then, this paper investigates the impacts of SREC on economic growth and CEI through rigorous econometric techniques. Based on the regression results, Shapley value decomposition is utilized to account for the cross-country inequalities of economic growth and CEI. The main findings are as follows: (1) There exist bidirectional Granger causalities between SREC, economic growth, and CEI, which shows there is a systematic link between the three variables. (2) All models demonstrate SREC negatively influences economic growth, indicating renewable energy deployment costs are urgent to be decreased with SREG increasing. Besides, capital investment and openness positively affect economic growth, but energy intensity has an opposite impact. (3) From the spatial heterogeneity perspective, the cross-country inequality in economic growth is primarily due to the regional inequality of capital investment, followed by energy intensity and SREC. By contrast, the impacts of labor and openness are negligible. (4) SREC has a negative effect on CEI. In addition, an inverted U-shaped nexus between economic growth and CEI is observed. Energy intensity positively affects CEI, while the impacts of urbanization and openness are insignificant. (5) From the spatial heterogeneity perspective, the cross-country CEI inequality is mostly caused by the inequality of energy intensity, followed by SREC, urbanization, and economic growth, while the contribution of the openness gap is little. This article provides important implications for low-carbon development in the BRI countries. | Exploring the effect of renewable energy on low-carbon sustainable development in the Belt and Road Initiative countries: evidence from the spatial-temporal perspective | 10.1007/s11356-021-13611-4 |
2021-08-01 | Laparoscopic cholecystectomy (LC) is a common surgical procedure in acute cholecystitis (AC). Patients often suffer from considerable postoperative pain and indigestion, which prolongs in-hospital stay. The enhanced recovery after surgery (ERAS) program has proven its efficacy in elective surgery and could hypothetically improve outcomes of emergency LC. Currently, there is no ERAS program for LC in patients with AC. A modified ERAS (mERAS) protocol was studied in a prospective, randomized non-blinded clinical trial (NCT03754751). The mERAS group consisted of 88 patients the control group of 101 patients. The modified protocol included a patient information brochure; minimizing drain use; local anesthesia; low-pressure pneumoperitoneum; PONV prophylaxis, early mobilization and oral diet. The primary outcome was postoperative length of stay (pLOS). The postoperative length of stay in the mERAS group was shorter (24 (21–45.5) h) than in the control (45 (41–68) h) ( p < 0.0001). One re-admission in the mERAS group was reported ( p = 0.466). There difference in complications was insignificant (mERAS 6.8% vs 5% p = 0.757). Post-operative pain intensity was significantly lower in the mERAS group immediately after awaking (3.7 ± 1.8 vs 5.4 ± 1.3 p < 0.0001), 2 h (3.3 ± 1.7 vs 4.9 ± 1.6 p = 0.0006), 6 h (2.9 ± 1.5 vs 4.2 ± 1.2 p < 0.0001), 12 h (2.7 ± 0.9 vs 4.1 ± 1.2 p = 0.0001) and 24 h after surgery (2.1 ± 1.2 vs 3 ± 1.2 p < 0.0001). The incidence of shoulder and neck pain was lower in mERAS group (13.6% vs 34.7% p = 0.0009). Peristalsis recovery was similar in both groups. The proposed protocol improved postoperative recovery and reduced hospital stay in patients with AC without increasing the rate of complications or re-admissions. | Modified enhanced recovery after surgery protocol in patients with acute cholecystitis: efficacy, safety and feasibility. Multicenter randomized control study | 10.1007/s13304-021-01031-5 |
2021-08-01 | In seismic data processing, low-frequency random noise with non-Gaussian and non-stationary characteristics heavily contaminates the reflected signals in Tarim area, which brings great difficulties in interpretation of seismic records in northwest China. To achieve more satisfied resolution, more greater fidelity, together with much higher increased signal-to-noise ratio (SNR), this paper proposes a SNR enhancement method based on the combination of variational mode decomposition (VMD) and Semi-soft Go Decomposition (Semi-Soft GoDec), named VMD-SSGoDec, which can realize the simplification of low-rank extraction in time–frequency representation (TFR) domain. Firstly, each trace of the rough seismic record is decomposed into several modes to reconstruct a component matrix by VMD. Due to the semi-low rank or approximate low-rank character of the desert low-frequency noise component matrix in TFR domain, secondly, we apply the Semi-soft GoDec, a low-rank matrix estimation to extract the low-frequency random noise components from the VMD results obtained in the first step. Repeating the above single-trace procedure to each trace rather than decomposing the entire record but use low-rank estimation once can lead to a more reduced dimension of the component matrix, and thus simplify the low-rank selection in Semi-soft GoDec. Finally, with the extracted random noise results in the second step, we can obtain the denoised record by making a difference with the original input. The proposed algorithm is tested by both synthetic record and field desert seismic data. Experimental results show outstanding advantages in low-frequency noise attenuation comparing with those of f-x deconvolution and SSWT-OptShrink. Both low-frequency random noise and surface waves are almost thoroughly attenuated by the proposed method, while the reflected signals are left nearly intact, revealing a significant enhancement in SNR. | A SNR Enhancement Method for Desert Seismic Data: Simplified Low-Rank Selection in Time–Frequency Decomposition Domain | 10.1007/s00024-021-02789-w |
2021-08-01 | Low-permeability media such as clay appear in nearly all hydrogeological systems. To date, although significant efforts have been put forward by hydrologists, transport mechanism is still not well understood in such media, especially in an aquifer-aquitard system. In this study, two-dimensional experiments of groundwater flow and solute transport were conducted in a clay-sand two-layer system to investigate the characteristics of flow and transport in such a system. Sodium chloride (NaCl) (a conservative tracer) from a tank was injected after passing by the pre-inlet reservoir where the mixing effect and flow transiency were analyzed. A new numerical model considering the mixing effect and flow transiency was developed to interpret the experimental data based on the finite-element COMSOL Multiphysics platform. Transport parameters were assessed by best fitting the observed breakthrough curves (BTCs). Several important results were obtained. Firstly, aquitard advection was found to be non-negligible and should be considered in a proper mathematical model for describing the transport process. Secondly, advective velocities were temporally variable and showed decreasing trends in the sand and clay layers, mainly due to the impacts of physical and biological clogging. Thirdly, the mixing effect in the pre-inlet reservoir led to a lower tracer concentration in the sand layer at early times. Finally, the observed BTCs exhibited early arrivals in the clay layer, possibly resulting from preferential flow pathways. These findings can provide hints for contamination remediation works in aquifer-aquitard systems. | Laboratory observations for two-dimensional solute transport in an aquifer-aquitard system | 10.1007/s11356-021-13123-1 |
2021-08-01 | Background Mesenchymal stem cell-based therapy is known to have the potential to induce angiogenesis. However, there are still some limitations regarding their clinical application. Photomodulation/photobiomodulation is non-invasive and non-toxic phototherapy able to stimulate cell viability, proliferation, differentiation, and migration, when the right irradiation parameters are applied. A review of the published articles on human conditioned-by-photobiomodulation mesenchymal cells in an in vitro set up was carried out. Our aim was to describe the studies' results and identify any possible tendency that might highlight the most suitable procedures. Methods A search in English of the PubMed database was carried out with the search criteria: photobiomodulation or photoactivation or photomodulation, and mesenchymal cells. All irradiations applied in vitro, on human mesenchymal cells, with wavelengths ranged from 600 to 1000 nm. Results The search yielded 42 original articles and five reviews. Finally, 37 articles were selected with a total of 43 procedures. Three procedures (7.0%) from 620 to 625 nm; 26 procedures (60.5%) from 625 to 740 nm; 13 procedures (30.2%) from 740 to 1000 nm; and one procedure (2.3%) with combinations of wavelengths. Of the 43 procedures, 14 assessed cell viability ( n = 14/43, 32.6%); 34 cell proliferation ( n = 34/43, 79.1%); 19 cell differentiation ( n = 19/43, 44.2%); and three cell migration ( n = 3/43, 7.0%). Conclusions Photobiomodulation is a promising technology that can impact on cell viability, differentiation, proliferation, or migration, leading to enhance its regenerative capacity. No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 . | The Effect of Photobiomodulation on Human Mesenchymal Cells: A Literature Review | 10.1007/s00266-021-02173-y |
2021-08-01 | In the chlorophyll biosynthesis pathway, the 8-vinyl group of the chlorophyll precursor is reduced to an ethyl group by 8-vinyl reductase. Two isozymes of 8-vinyl reductase have been described in oxygenic photosynthetic organisms: one encoded by BciA and another by BciB . Only BciB contains an [Fe-S] cluster and most cyanobacteria harbor this form; whereas a few contain BciA . Given this disparity in distribution, cyanobacterial BciA has remained largely overlooked, which has limited understanding of chlorophyll biosynthesis in these microorganisms. Here, we reveal that cyanobacterial BciA encodes a functional 8-vinyl reductase, as evidenced by measuring the in vitro activity of recombinant Synechococcus and Acaryochloris BciA. Genomic comparison revealed that BciB had been replaced by BciA during evolution of the marine cyanobacterium Synechococcus , and coincided with replacement of Fe-superoxide dismutase (SOD) with Ni-SOD. These findings imply that the acquisition of BciA confers an adaptive advantage to cyanobacteria living in low-iron oceanic environments. | Distribution and functional analysis of the two types of 8-vinyl reductase involved in chlorophyll biosynthesis in marine cyanobacteria | 10.1007/s00203-021-02348-w |
2021-08-01 | Niedertemperatur-Wärme- und Kältenetze (NT-WK-Netze) sind innovative Ansätze zur Deckung des Wärme- und Kältebedarfs insbesondere in städtischen Gebieten. Fernwärmesysteme stehen vor einem Übergang zu sinkenden Netztemperaturen und zeitgleich auch vor einem Übergang zu einem Anstieg der Nutzung erneuerbarer Energien auf bis zu 100 %. NT-WK-Netze wurden erstmals vor etwa 10 Jahren in der Schweiz installiert. In Österreich haben sich einige Forschungsprojekte mit der Machbarkeit dieser Netze beschäftigt und in Wien sind zwei kleine NT-WK-Netze in Betrieb. Im Allgemeinen ist das Wissen über die Hauptkomponenten von NT-WK-Netzen gut entwickelt. Die eigentliche Herausforderung ist nicht die Auslegung der einzelnen Komponenten, sondern das hydraulische und thermische Zusammenspiel aller Komponenten mit seinen hohen Freiheitsgraden. Standardverfahren für die technische Auslegung von gemeinsamen Fernwärmenetzen und geothermischen Anlagen sind daher nicht geeignet. Aus diesem Grund ist ein volldynamisches Simulationstool mit gekoppelten thermohydraulischen Prozessen für die Dimensionierung der Komponenten und deren Interaktion mit dem Netz wichtig. Im Oktober 2018 starteten die Autor/innen ein interdisziplinäres angewandtes Forschungsprojekt mit dem Ziel, ein NT-WK-Netz für das ehemalige Militärlager ,,Martinek-Kaserne“ in der Stadt Baden südlich von Wien zu entwickeln, für das ein neues urbanes Mischnutzungsquartier geplant ist. Wesentliche Elemente sind die Nutzung von industrieller Niedertemperatur-Abwärme aus Prozessen der benachbarten NÖM-Molkerei sowie die Entwicklung von Sanierungs- und Umnutzungskonzepten für die denkmalgeschützten Gebäude. Die Projektergebnisse zeigten eindeutig für den Standort ein hohes Realisierungspotenzial für ein NT-WK-Netz am Standort mit der Abwärme der NÖM sowie geothermischer Speicherung in Erdsondenfeldern. Das Netz kann unabhängig von der zukünftigen Nutzung wirtschaftlich betrieben werden. Die Ergebnisse des Projekts sind ein wichtiger erster Schritt, der zur breiteren Umsetzung von NT-WK-Netzen in Österreich beiträgt. Es wird sowohl das Screening von Standorten als auch die Planung von Netzdesigns ermöglichen. Das Konsortium hat sich zum Ziel gesetzt, potenzielle Entwickler bei der Realisierung des NT-WK-Netzes in der ,,Martinek-Kaserne“ in naher Zukunft zu unterstützen. Low-temperature heating and cooling (LTHC) grids are innovative approaches to meet the heating and cooling demand especially in urban areas. In October 2018 the authors started the interdisciplinary applied research project ,,Smart Anergy Quarter Baden“ (SANBA), with the aim of developing a LTHC grid for the former military camp ,,Martinek-Kaserne“ in Baden, south of Vienna, which was abandoned in 2014 and for which there are plans to develop a new urban mixed-use quarter. The main challenge for this project is the condition of the buildings which date back to the 1930s and which are protected by cultural heritage. The need for refurbishment of the buildings is given regardless of their future use. The refurbishment of the buildings so that they are suitable for a low-temperature heating and cooling distribution system is a new aspect for the owner, the Austrian Federal Ministry of Defence. Key elements for the LTHC grid are the use of industrial low-temperature waste heat from processes in the neighbouring NÖM dairy plant as well as the development of refurbishment and conversion concepts for the protected buildings. | Niedertemperatur-Wärme- und Kältenetze für denkmalgeschützte Bestandsgebäude mit industrieller Abwärme und Geothermie | 10.1007/s00502-021-00896-z |
2021-08-01 | Self-organization, physicochemical properties (specific electrical conductivity, surface tension), UV absorption, and fluorescence of aqueous herbicide compositions based on N -(phosphonomethyl)glycine and plant growth regulator succinic acid (SA) were studied in a range of herbicide concentrations of 1·10 −19 −1·10 −1 g L −1 at the constant concentrations of SA 1·10 −3 g L −1 (series 1 ) and 1·10 −13 g L −1 (series 2 ). Such compositions are used in agriculture for decreasing toxic effects on cultural plants and environment. A comparison of the nonmonotonic concentration dependences of the size and ξ-potential of the disperse phase, properties, and bioeffects of systems 1 and 2 revealed significant distinctions in these compositions in the ability of self-organization and surfactant properties, which can cause, as a whole, their substantial difference in the degree of harmful influence on aquatic life and higher plants. The influence of the compositions of series 1 is accompanied by a decrease in the harmful effect on the chosen biological test objects compared to the herbicide, and that of series 2 results in an almost complete elimination of the harmful effect against multicellular organisms (cladocerans and wheat roots) and an insignificant effect on unicellular aquatic life (infusoria and algae). The influence of the compositions of series 2 on aquatic life is related to the formation of a negatively charged disperse phase accompanied by an increase in the fluorescence intensity in a range of 300–360 nm (λ exc = 225 nm). | Physicochemical and biological properties of aqueous herbicide compositions based on N-(phosphonomethyl)glycine and succinic acid in a range of low concentrations | 10.1007/s11172-021-3245-9 |
2021-07-29 | Poor soil chemical fertility and climate change restrict pearl millet grain yield in Niger Republic. Apart from the seedball technology, which targets majorly early phosphorus supply to the plants, the recommended practices of mineral fertilization and seed treatments (coating and priming) are barely affordable to the local farmers in particular. In the case of female farmers, who usually have chemically infertile farmlands often located far away from their homestead, low pearl millet grain yield can be exacerbated. In quest for a cheap, affordable, and effective solution, we hypothesized that the application of sanitized human urine (Oga), in combination with organic manure (OM) or solely, increases pearl millet panicle yield in women’s fields and on different local soils. In on-farm large -N trials ( N = 681) with women farmers in two regions of Niger (Maradi, Tillabery), pearl millet panicle yields were compared between the control (farmer practice), and a combination of Oga and OM in the first and second year, and Oga alone in the third year. Our results showed an average panicle yield increase of about +30%, representing +200 to +300 kg ha −1 . Major factors determining the yield effect are season, village, and local soil type. This study shows for the first time that Oga innovation can be used to increase pearl millet panicle yield particularly in the low fertile soils of women’s farmlands in Niger. Oga innovation is affordable, locally available, and does not pose a risk to resource-poor female farmers of Niger. | Sanitized human urine (Oga) as a fertilizer auto-innovation from women farmers in Niger | 10.1007/s13593-021-00675-2 |
2021-07-27 | Herein, a KFeS 2 whisker was formed in mass production at a low temperature, with waste cold-rolling sludge as Fe source, which exhibited good performance in the removal of Zn/Ni from real electroplating effluent. At laboratory scale, KFeS 2 was generated at 80 °C by the hydrothermal method, and KFeS 2 whisker grew radially with the extension of the reaction time. This method was applied at pilot scale, where a similar KFeS 2 whisker was also produced with waste cold-rolling sludge as Fe source, and a residual brownish supernatant was observed after the reaction and then completely recycled in the next round for KFeS 2 synthesis. After recycling five times, the produced KFeS 2 whisker did not change. The drying and storage of KFeS 2 have also been verified. Freeze drying and vacuum drying were applicable, whereas air drying was not profitable. Moreover, the efficiency of Zn/Ni removal using undried KFeS 2 was similar to that of dried KFeS 2 . The efficiencies of Zn/Ni removal using KFeS 2 were apparently higher those of common reagents for wastewater treatment. | Low-temperature conversion of Fe-rich sludge to KFeS2 whisker: a new flocculant synthesis from laboratory scale to pilot scale | 10.1186/s42834-021-00098-4 |
2021-07-27 | Background Many lower-limb exoskeletons have been developed to assist gait, exhibiting a large range of control methods. The goal of this paper is to review and classify these control strategies, that determine how these devices interact with the user. Methods In addition to covering the recent publications on the control of lower-limb exoskeletons for gait assistance, an effort has been made to review the controllers independently of the hardware and implementation aspects. The common 3-level structure (high, middle, and low levels) is first used to separate the continuous behavior (mid-level) from the implementation of position/torque control (low-level) and the detection of the terrain or user’s intention (high-level). Within these levels, different approaches (functional units) have been identified and combined to describe each considered controller. Results 291 references have been considered and sorted by the proposed classification. The methods identified in the high-level are manual user input, brain interfaces, or automatic mode detection based on the terrain or user’s movements. In the mid-level, the synchronization is most often based on manual triggers by the user, discrete events (followed by state machines or time-based progression), or continuous estimations using state variables. The desired action is determined based on position/torque profiles, model-based calculations, or other custom functions of the sensory signals. In the low-level, position or torque controllers are used to carry out the desired actions. In addition to a more detailed description of these methods, the variants of implementation within each one are also compared and discussed in the paper. Conclusions By listing and comparing the features of the reviewed controllers, this work can help in understanding the numerous techniques found in the literature. The main identified trends are the use of pre-defined trajectories for full-mobilization and event-triggered (or adaptive-frequency-oscillator-synchronized) torque profiles for partial assistance. More recently, advanced methods to adapt the position/torque profiles online and automatically detect terrains or locomotion modes have become more common, but these are largely still limited to laboratory settings. An analysis of the possible underlying reasons of the identified trends is also carried out and opportunities for further studies are discussed. | Review of control strategies for lower-limb exoskeletons to assist gait | 10.1186/s12984-021-00906-3 |
2021-07-24 | Salinity drops in estuaries after heavy rains are expected to increase in frequency and intensity over the next decades, with physiological and ecological consequences for the inhabitant organisms. It was investigated whether low salinity stress increases predation risk on three relevant commercial bivalves in Europe. In laboratory, juveniles of Venerupis corrugata, Cerastoderma edule , and the introduced Ruditapes philippinarum were subjected to low salinities (5, 10 and control 35) during two consecutive days and, afterwards, exposed to one of two common predators in the shellfish beds: the shore crab Carcinus maenas and the gastropod Bolinus brandaris, a non-indigenous species present in some Galician shellfish beds . Two types of choice experiment were done: one offering each predator one prey species previously exposed to one of the three salinities, and the other offering each predator the three prey species at the same time, previously exposed to one of the three salinities. Consumption of both predators and predatory behaviour of C. maenas (handling time, rejections, consumption rate) were measured. Predation rates and foraging behaviour differed, with B. brandaris being more generalist than C. maenas . Still, both predators consumed significantly more stressed (salinity 5 and 10) than non-stressed prey. The overall consumption of the native species C. edule and V. corrugata was greater than that of R. philippinarum , likely due to their vulnerability to low salinity and physical traits (e.g., thinner shell, valve gape). Increasing precipitations can alter salinity gradients in shellfish beds, and thus affect the population dynamics of harvested bivalves via predator–prey interactions. | Predation risk increases in estuarine bivalves stressed by low salinity | 10.1007/s00227-021-03942-8 |
2021-07-23 | In the past decade, therapeutic hypothermia using a variety of low-cost devices has been widely implemented in India and other low-and middle-income countries (LMIC) without adequate evidence of either safety or efficacy. The recently reported data from the world’s largest cooling trial (HELIX - hypothermia for encephalopathy in low- and middle-income countries) in LMIC provides definitive evidence of harm of cooling therapy with increase in mortality (number to harm 9) and lack of neuroprotection. Although the HELIX participating centers were highly selected tertiary neonatal intensive care units in South Asia with facilities for invasive ventilation, cardiovascular support, and 3 Tesla magnetic resonance imaging (MRI), and the trial used state-of-the-art automated servo-controlled cooling devices, a therapy that is harmful under such optimal conditions cannot be safe in low-resource settings that cannot even afford servo-controlled cooling devices. The HELIX trial has set a new benchmark for conducting high quality randomized controlled trials in terms of research governance, consent, ethics, follow-up rates, and involvement of parents. The standard care for neonatal encephalopathy in LMIC should remain normothermia, with close attention to prevention of hyperthermia. There is no role for therapeutic hypothermia in LMIC as the efficacy of hypothermia is dependent on the population, and not merely on the level of neonatal intensive care facilities. Future research should explore timings and origins of brain injury and prevention of brain injury in LMIC, with a strong emphasis on academic research capacity building and patient and public engagement. | Rise and Fall of Therapeutic Hypothermia in Low-Resource Settings: Lessons from the HELIX Trial | 10.1007/s12098-021-03861-y |
2021-07-23 | A new inter-cluster DC capacitor voltage balancing scheme for a delta connected modular multilevel cascaded converter (MMCC)-based static synchronous compensator (STATCOM) is presented. A detailed power flow analysis of applying negative sequence current (NSC) and zero-sequence current (ZSC) injection methods in addressing the issue of inter-cluster DC voltage imbalance under unbalance grid voltage is carried out. A control scheme is proposed which integrates both inter-cluster methods using a quantification factor Q F . This is used to achieve the sharing of the inter-cluster active power between the NSC and ZSC injection methods. An accurate method of determining the quantification factor is also presented. The proposed method offers better sub-module DC capacitor voltage balancing and prevents converter overcurrent. The influence of unbalanced grid voltage on the delta connected MMCC-based STATCOM rating using this integrated cluster balancing technique is investigated. The control scheme is verified with a 5 kV 1.2MVA MMCC-STATCOM using 3-level bridge sub-modules, and the results show the advantages of the proposed method over other inter-cluster methods. | Inter-cluster voltage balancing control of a delta connected modular multilevel cascaded converter under unbalanced grid voltage | 10.1186/s41601-021-00203-0 |
2021-07-20 | Previous observational analyses have shown a declining rainfall trend over Israel, mostly statistically insignificant. The current study, for the period 1975–2020, undermines these findings, and the alarming future projections, and elaborates other ingredients of the rain regime. No trend is found for the annual rainfall, reflecting a balance between a negative trend in the number of rainy days and a positive trend in the daily rainfall intensity, both on the order of 2.0%/decade. In the mid-winter, the rainfall and the daily intensity increased, while both declined in the autumn and spring, implying a contraction of the rainy season. The time span between accumulation of 10% and 90% of the annual rainfall, being 112 days on the average, shortened by 7 days during the study period. This is also expressed by an increase of the Seasonality Index, indicating that the regional climate is shifting from “markedly seasonal with a long dry season” to “most rain in ≤3 months.” The intra-seasonal course of the rainfall trend corresponds to that of the occurrence and intensity of the Cyprus Lows and the Mediterranean Oscillation. The contraction of the rainy season and the increase in the daily intensity have far-reaching environmental impacts in this vulnerable region. | Recent changes in the rain regime over the Mediterranean climate region of Israel | 10.1007/s10584-021-03161-6 |
2021-07-19 | The Salawusu aquifer in the Ordos coalfield is characterized by large thickness and water abundance. Most wells built in such water-rich sand layers are constructed by artificial freezing method. After thawing of the frozen wall, the original crack in the shaft wall gradually expands, penetrates, and even cracks because of the high external water pressure, then, resulting in water inrush and sand collapse. In order to solve the above problems, we adopted the method of laboratory tests to conduct the properties tests of cement slurry with various additives in low temperature environment. The setting time, strength, and rheological properties of the cement slurry with addition of NaCl, Ca(HCOO) 2 , CaCl 2 , and sodium silicate were studied respectively. The research results showed that NaCl, Ca(HCOO) 2 , CaCl 2 , and sodium silicate could effectively shorten the setting time at low temperature. The addition of NaCl, Ca(HCOO) 2 , and CaCl 2 in cement slurry has a critical amount. When NaCl, Ca(HCOO) 2 , and CaCl 2 amounts were lower than the critical amount, the setting time of the cement slurry was negatively correlated with the addition amount; while when they were higher than the critical amount, the setting time was positively correlated with the addition amount. For cement slurry with sodium silicate, the setting time was negatively correlated with the sodium silicate amount and temperature. The viscosity and shear stress of cement slurry without addition were less affected by temperature, and NaCl, Ca(HCOO) 2 , or CaCl 2 could slightly reduce the viscosity and shear stress. With water-cement ratio of 1:1 and 5%NaCl was added, the cement slurry achieved good results for ground grouting in field application. It has obvious effects on flood control and sand fixation of water-rich sand layer, and could exert great influence on water blocking, material source reducing, and dynamic water head decreasing. | Properties and field application of the grouting material for water blocking during thawing of frozen wall of deep sand layer | 10.1007/s12517-021-07826-5 |
2021-07-17 | Dynamic changes in growth characteristics and endogenous hormone contents in the leaves and roots of Sophora davidii seedlings under low-phosphorus stress were studied to provide a reference for further study of the internal regulatory mechanism of the response strategy of this species to low-phosphorus stress. Normal phosphorus (0.5 mmol KH 2 PO 4 , NP) and low-phosphorus (0.005 mmol KH 2 PO 4 , LP) levels and different treatment times were applied to study growth characteristics, phosphorus utilization and hormone contents in the leaves and roots of potted Sophora davidii by tissue culture and sand culture. The results first showed that compared with NP, LP significantly decreased the plant height, leaf length, leaf width, leaf area, leaf perimeter and root–shoot ratio by 20.10%, 21.08%, 22.73%, 51.33%, 24.94% and 18.92%, respectively. LP decreased the total root length and root dry weight, and increased the root surface area, average root diameter, root tip number, root volume and dry weight of the aerial part on day 9, but these effects were not significant. Second, compared with NP, LP significantly decreased P contents in the aerial part and roots and P uptake efficiency in the aerial part and roots on day 9 by 23.33%, 53.89%, 14.04% and 58.06%, respectively. LP significantly increased the P utilization efficiency and leaf acid phosphatase (ACP) activity on day 9 by 82.79% and 84.38%, respectively. LP increased root ACP activity on day 9, but the effect was not significant. Third, compared with NP, LP significantly decreased abscisic acid (ABA), cytokinin (CTK) and strigolactone (SL) contents in leaves by 21.52%, 36.65% and 45.86%, respectively, and significantly increased gibberellin (GA) contents in roots by 28.92% on day 9. LP decreased GA contents in leaves and CTK contents in roots and increased indole-3-acetic acid (IAA) contents in leaves and roots and ABA and SL contents in roots on day 9, but these effects were not significant. Correlation analysis indicated that endogenous hormone contents in Sophora davidii leaves and roots under different treatment conditions had certain correlations with growth characteristics. In conclusion, Sophora davidii can improve its P utilization efficiency by changing growth characteristics and endogenous hormones to enhance its adaptive response to low-phosphorus stress. | Response of growth characteristics and endogenous hormones of Sophora davidii to low-phosphorus stress | 10.1007/s11738-021-03284-4 |
2021-07-15 | Background This study aimed to compare the clinical efficacy of digital subtraction angiography (DSA) combined arterial thrombectomy versus simple arterial thrombectomy in the treatment of acute lower limb ischemia (ALI). Methods This retrospective cohort study collected the clinical data from 124 patients (128 affected lower limbs) with ALI who underwent emergency surgery from March 2010 to November 2019. Patients were consecutively divided into Group A and Group B. Patients in Group A underwent simple arterial thrombectomy via the Fogarty catheterization. Patients in Group B underwent arterial thrombectomy, and the DSA was performed during the surgery. The differences in the success rate of primary surgery, the second intervention rate, and the amputation/mortality rate within 30-days after surgery were compared. Results In Group A, 4 of 70 limbs (5.7%) were amputated, 54 of 70 limbs (77.1%) had improved blood flow, 14 of 70 limbs (20.0%) received a second intervention, and 3 of 68 patients (4.4%) died within 30 days. In Group B, 1 of 58 limbs (1.7%) was amputated, 56 of 58 limbs (96.6%) had improved blood flow, 3 of 58 limbs (5.2%) received a second intervention, and 2 of 56 patients (3.5%) died within 30-days. The success rate of primary surgery, the second intervention rate, and the amputation rate of Group B were significantly lower than Group A ( P < 0.05). Conclusion Arterial thrombectomy combined with DSA may effectively improve the clinical efficacy of patients with ALI. | Comparison of digital subtraction angiography combined arterial thrombectomy versus simple arterial thrombectomy in the treatment of acute lower limb ischemia | 10.1186/s12893-021-01297-x |
2021-07-14 | Background and objective Recently, dietary restriction of fermentable carbohydrates (a low-FODMAP diet) in combination with a gluten-free diet (GFD) has been proposed to reduce the symptoms in irritable bowel syndrome (IBS) patients. Different studies reported that IBS has been associated with dysbiosis in the gut microbiota. Additionally, a few studies have reported inflammation in the gastrointestinal (GI) system of adults with IBS. In this study, we aimed to investigate the effects of low FODMAP-gluten free diet (LF-GFD) on clinical symptoms, intestinal microbiota diversity, and fecal calprotectin (FC) level in Iranian patients with IBS. Design In this clinical trial study, 42 patients with IBS (Rome IV criteria) underwent LF-GFD intervention for 6 weeks. Symptoms were assessed using the IBS symptom severity scoring (IBS-SSS), and fecal samples were collected at baseline and after intervention and analyzed by quantitative 16 S rRNA PCR assay. The diversity of gut microbiota compared before and after 6 weeks of dietary intervention. FC was also analyzed by the ELISA method. Results Thirty patients (mean age 37.8 ± 10.7 years) completed the 6-week diet. The IBS-SSS was significantly ( P = 0.001) reduced after LF-GFD intervention compared to the baseline. Significant microbial differences before and after intervention were noticed in fecal samples. A significant increase was found in Bacteroidetes , and the Firmicutes to Bacteroidetes (F/B) ratio was significantly ( P = 0.001) decreased after the dietary intervention. The value of FC was significantly decreased after 6 weeks of dietary intervention ( P = 0.001). Conclusions Our study suggests that patients with IBS under an LF-GFD had a significant improvement in IBS symptoms severity, with reduced FC level following normalization of their gut microbiota composition. Further rigorous trials are needed to establish a long-term efficacy and safety of this dietary intervention for personalized nutrition in IBS. Clinical Trial Registry Number: IRCT20100524004010N26. | Influence of low FODMAP-gluten free diet on gut microbiota alterations and symptom severity in Iranian patients with irritable bowel syndrome | 10.1186/s12876-021-01868-5 |
2021-07-14 | Along with the development and construction of new roads, a significant percentage of the existing road network also need reconstruction and renovation to sustain the momentum of the economic growth of any developing country like India. Role of state agencies involved in road maintenance, assessment and monitoring of pavement conditions is of utmost importance for maintaining good quality pavement often assessed by riding comfort signified by pavement roughness. A large number of devices have been developed around the world for roughness measurement. With significant developments of costly automated and high-output road survey equipment in the recent past for road network condition monitoring, it is possible now to conduct a survey at normal traffic flow speed, may not be a feasible option for state agencies of developing/underdeveloped countries. In this work, a new low-cost Ultrasonic Roughometer (Us-R) device is developed for the measurement of pavement roughness. Us-R has the added benefit of acquiring precise roughness data along the wheel path with ease of operating without hampering the normal traffic flow. MERLIN is used to calibrate the new device’s measuring capacities fitted in a bi-cycle and motorcycle. The IRI value collected by fitting Us-R device in both bi-cycle and motorcycle differs within 5%, producing a high correlation. The roughness values collected using the Us-R are also consistent with time. The easy fixing of Us-R device with a readily available vehicle like bi-cycle/motorcycle makes it user-friendly and a good option for evaluating road roughness in underdeveloped and developing countries. The newly developed low-cost device can be used advantageously over existing devices present in the market for roughness measurement by state agencies involved in road maintenance of developing country like India. | Low cost ultrasonic roughometer for pavement roughness measurement | 10.1007/s41062-021-00521-0 |
2021-07-13 | Background The combination of imaging and therapeutic agents in the same smart nanoparticle is a promising option to perform a minimally invasive imaging guided therapy. In this study, Low density lipoproteins (LDL), one of the most attractive biodegradable and biocompatible nanoparticles, were used for the simultaneous delivery of Paclitaxel (PTX), a hydrophobic antitumour drug and an amphiphilic contrast agent, Gd-AAZTA-C17, in B16-F10 melanoma cell line. These cells overexpress LDL receptors, as assessed by flow cytometry analysis. Results PTX and Gd-AAZTA-C17 loaded LDLs (LDL-PTX-Gd) have been prepared, characterized and their stability was assessed under 72 h incubation at 37 °C and compared to LDL loaded with Gd-AAZTA-C17 (LDL-Gd) and LDL-PTX. The cytotoxic effect of LDL-PTX-Gd was evaluated by MTT assay. The anti-tumour drug loaded into LDLs showed a significantly higher toxicity on B16-F10 cells with respect to the commercially available formulation Paclitaxel kabi (PTX Kabi) used in clinical applications. Tumour cells uptake was initially assessed by ICP-MS and MRI on B16-F10 cell line. By the analysis of the image signal intensity, it was possible to extrapolate the amount of internalized PTX indirectly by the decrease of relaxation times caused by Gd, proportional to its concentration. Finally, the treatment with PTX loaded LDL on B16-F10 tumour bearing mice resulted in a marked reduction of tumour growth compared to the administration of PTX Kabi alone. Conclusions LDLs are selectively taken-up by tumour cells and can be successfully exploited for the selective delivery of Paclitaxel and imaging agents. For the first time the anon invasive “in vivo” determination of the amount of PTX accumulated in the tumour was possible, thanks to the use of theranostic agents of natural origin. Graphic abstract | LDL mediated delivery of Paclitaxel and MRI imaging probes for personalized medicine applications | 10.1186/s12951-021-00955-9 |
2021-07-13 | Objective To investigate the impact of microecological preparation combined with modified low-carbon diet on the glucolipid metabolism and cardiovascular complication in obese patients. Methods From August 2017 to July 2020, 66 obese patients were recruited, and administrated with an modified low-carbon diet with (group A) or without (Group B) microecology preparation and a balanced diet in control group (group C) for 6 months. Meanwhile, 20 volunteers administrated with a balanced diet were recruited as the healthy control group (group D). Results After 6-month intervention, obese subjects in group A and B showed significant improvement of body and liver fat mass, reduction of serum lipid levels, intestinal barrier function markers, insulin resistance index (IRI), high blood pressure (HBP) and carotid intima thickness, as compared with subjects in group C. More importantly, subjects in group A had better improvement of vascular endothelial elasticity and intimal thickness than subjects in group B. However, these intervention had no effect on carotid atherosclerotic plaque. Conclusion Administration of microecological preparation combined with modified low-carbon diet had better improvement of intestinal barrier function, glucose and lipid metabolism, and cardiovascular complications than low-carbon diet in obese patients, but the effect of a simple low-carb diet on carotid atherosclerotic plaque need to be further addressed. | Microecological preparation combined with an modified low-carbon diet improves glucolipid metabolism and cardiovascular complication in obese patients | 10.1186/s13098-021-00697-6 |
2021-07-09 | Background Recently, pine wood nematode (PWN, Bursaphelenchus xylophilus ) has been found in the extreme cold area of northeast China. The third-stage dispersal juvenile (DJ3) of PWN, which is a long-lived stress-resistant stage, plays an important role in the process of PWN spreading to low-temperature areas, as this stage can survive under unfavorable conditions. Results Weighted correlation network analysis (WGCNA) was used to analyze the expression patterns of 15,889 genes included in 21 RNA-Seq results of PWN at DJ3 and the other 6 different stages, and a total of 12 coexpression modules were obtained. Among them, the magenta module has the highest correlation with DJ3, which included a total of 652 genes. KEGG enrichment analysis showed that most of the genes in the magenta module were involved in metabolic processes, which were related to autophagy and longevity regulation. These pathways included starch and sucrose metabolism, which contains trehalose metabolism. To explore the function of trehalose in DJ3 formation and survival under − 20 °C, a trehalose-6-phosphate synthase encoding gene ( Bx-tps ), a trehalose-6-phosphate phosphatase encoding gene ( Bx-tpp ) and 7 trehalase encoding genes ( Bx-tre s) were identified and investigated. The expression of these 9 genes was related to the formation of DJ3. A treatment under − 20 °C induced the accumulation of trehalose. The survival rate of DJ3 at -20 °C reduced after silencing of any of these trehalose metabolism genes. Further analysis suggested that two trehalose synthesis genes were highly correlated with DJ3 and might be involved in autophagy by regulating with energy conversion related genes. Conclusions The above results indicated that trehalose metabolism promotes DJ3 formation and helps DJ3 survive at -20 °C. Although trehalose accumulation is favorable for DJ3 to cope with low-temperature stress, multiple trehalose metabolism genes need to work together. There may be a multi-path regulated physiological process involving trehalose synthesis genes under low-temperature stress resistance. This physiological process may regulate the formation and maintenance of DJ3 through autophagy and energy conversion. | Trehalose in pine wood nematode participates in DJ3 formation and confers resistance to low-temperature stress | 10.1186/s12864-021-07839-0 |
2021-07-08 | Background Microbial contamination of edible low moisture food poses a significant public health risk for human. In this study, the microbial quality of sweet dehulled sesame seed croquettes, salted dehulled sesame seed and the raw sesame seed, sold under ambient conditions were examined. The samples were collected in the cities of Burkina Faso. The first type is sweet dehulled sesame seed croquettes (n 1 = 25); the second type is salted dehulled sesame seed (n 2 = 25) and the third type is raw sesame seed (n 3 = 25). Assessment of the microbial quality was based on the total aerobic mesophilic bacteria, the thermotolerant coliforms, the yeasts and moulds, the E. coli, and the Salmonella spp. using ISO methods. Results The results showed the presence of microorganisms varying from <1.0 to 1.72 × 10 5 CFU g − 1 for thermotolerant coliforms, from <1.0 to 6,12 × 10 6 CFU g − 1 for the total mesophilic aerobic flora and from <1.0 to 8.10 × 10 5 CFU g − 1 for yeasts and moulds. The higher contaminations rates were mostly observed in raw sesame seed samples. No E coli or Salmonella pathogens were detected. Based on international standards of dehydrated food, 50.67% of the ready to eat sesame are satisficing while 17.33% are acceptable and 32% are not satisficing. Conclusion Attention should be emphasized on the processing practices, especially in crowded places where RTE sesames seeds are mostly sold. The high numbers of all microbial groups in these sesame seed samples suggested that the production of RTE sesame seed should be improved by better hygiene. This study highlights also that RTE sesame seed might harbor a wide range of microorganisms when processes are weak of hygiene. | Assessment of the sanitary quality of ready to eat sesame, a low moisture street food from Burkina Faso | 10.1186/s12866-021-02269-0 |
2021-07-07 | Carbonate rocks are important targets of hydrocarbon exploration in the Gucheng area, Tarim Basin. In this study, the thin sections, carbon and oxygen isotopes, trace elements and rare earth elements of 25 carbonate samples from the Upper Cambrian and the Ordovician are conducted to research the original sedimentary environment of these carbonate rocks. The carbonate rocks have undergone high-temperature hydrothermal activity due to the movement of magmatic water in the Permian based on carbon and oxygen isotope and Eu anom data. The Upper Cambrian and Ordovician are divided into five third-order sequences based on carbon isotopes and natural gamma-ray spectral logging combined with previous researches. The SQ1~SQ3 in the Upper Cambrian and Middle-Lower Ordovician predominant in sea-level decline cycle, whereas the SQ4 and SQ5 in the Middle-Upper Ordovician are dominated by sea-level rise cycle. Ce anom and Z values are suitable to analyze the redox environment and paleosalinity quantitatively, which suggests an oxidizing and marine origin in this area. The dolomites are formed in a paleoenvironment with a higher salinity, a stronger oxidation and a lower falling sea level than that of the limestones. | Geochemical characteristics of carbonates and indicative significance of the sedimentary environment based on carbon-oxygen isotopes, trace elements and rare earth elements: case study of the Lower Paleozoic carbonates in the Gucheng area, Tarim Basin, China | 10.1007/s12517-021-07574-6 |
2021-07-06 | Abstract Abandoned roadways of coal mines are suitable for compressed air energy storage after proper treatment with grouting reinforcement and concrete lining. According to the theoretical analysis, the rock mass and concrete lining will experience cyclic tensile stress in the air injection-withdrawal process which is unfavorable to the long-term stability of the roadway. At present, few researches have focused on mechanical properties of rock under cyclic tensile stress. Therefore, cyclic tests were conducted for sandstones under different maximum tensile stresses and different cyclic frequencies, respectively. The test results showed that there was little damage in the sandstone until the maximum tensile stress was over the threshold which was about 75% of the average tensile strength of the sandstone. Besides, the rock was damaged more easily under lower cyclic frequency. Based on the testing results, a viscoelastic-plastic model for sandstone was constructed under cyclic tensile stress. The model parameters were fitted by optimization analysis method and used to predict mechanical behaviors of the sandstone. The results showed that the response of the rock could be well obtained by the proposed model. Article highlights Lower cyclic frequency of tensile stress makes sandstone sample more favorable to be broken. The sample tested under low cyclic frequency of tensile stress will generate time-depending tensile strain inside. The time-depending tensile strain evolution properties of the sample under different testing conditions can be uncovered by a model constructed by different basic mechanical elements and a self-defined element. | Experimental investigation and viscoelastic-plastic model for sandstone under cyclic tensile stress | 10.1007/s40948-021-00272-3 |
2021-07-03 | Elastomeric nanostructures are normally expected to fulfill an explicit mechanical role and therefore their mechanical properties are pivotal to affect material performance. Their versatile applications demand a thorough understanding of the mechanical properties. In particular, the time dependent mechanical response of low-density polyolefin (LDPE) has not been fully elucidated. Here, utilizing state-of-the-art PeakForce quantitative nanomechanical mapping jointly with force volume and fast force volume, the elastic moduli of LDPE samples were assessed in a time-dependent fashion. Specifically, the acquisition frequency was discretely changed four orders of magnitude from 0.1 up to 2 k Hz. Force data were fitted with a linearized DMT contact mechanics model considering surface adhesion force. Increased Young’s modulus was discovered with increasing acquisition frequency. It was measured 11.7 ± 5.2 MPa at 0.1 Hz and increased to 89.6 ± 17.3 MPa at 2 kHz. Moreover, creep compliance experiment showed that instantaneous elastic modulus E 1 , delayed elastic modulus E 2 , viscosity η , retardation time τ were 22.3 ± 3.5 MPa, 43.3 ± 4.8 MPa, 38.7 ± 5.6 MPa s and 0.89 ± 0.22 s, respectively. The multiparametric, multifunctional local probing of mechanical measurement along with exceptional high spatial resolution imaging open new opportunities for quantitative nanomechanical mapping of soft polymers, and can potentially be extended to biological systems. | Quantitative Nanomechanical Mapping of Polyolefin Elastomer at Nanoscale with Atomic Force Microscopy | 10.1186/s11671-021-03568-1 |
2021-07-03 | Background The heterogeneous subtypes and stages of epithelial ovarian cancer (EOC) differ in their biological features, invasiveness, and response to chemotherapy, but the transcriptional regulators causing their differences remain nebulous. Methods In this study, we compared high-grade serous ovarian cancers (HGSOCs) to low malignant potential or serous borderline tumors (SBTs). Our aim was to discover new regulatory factors causing distinct biological properties of HGSOCs and SBTs. Results In a discovery dataset, we identified 11 differentially expressed genes (DEGs) between SBTs and HGSOCs. Their expression correctly classified 95% of 267 validation samples. Two of the DEGs, TMEM30B and TSPAN1 , were significantly associated with worse overall survival in patients with HGSOC. We also identified 17 DEGs that distinguished stage II vs. III HGSOC. In these two DEG promoter sets, we identified significant enrichment of predicted transcription factor binding sites, including those of RARA, FOXF1, BHLHE41, and PITX1. Using published ChIP-seq data acquired from multiple non-ovarian cell types, we showed additional regulatory factors, including AP2-gamma/TFAP2C, FOXA1, and BHLHE40, bound at the majority of DEG promoters. Several of the factors are known to cooperate with and predict the presence of nuclear hormone receptor estrogen receptor alpha (ER-alpha). We experimentally confirmed ER-alpha and PITX1 presence at the DEGs by performing ChIP-seq analysis using the ovarian cancer cell line PEO4. Finally, RNA-seq analysis identified recurrent gene fusion events in our EOC tumor set. Some of these fusions were significantly associated with survival in HGSOC patients; however, the fusion genes are not regulated by the transcription factors identified for the DEGs. Conclusions These data implicate an estrogen-responsive regulatory network in the differential gene expression between ovarian cancer subtypes and stages, which includes PITX1. Importantly, the transcription factors associated with our DEG promoters are known to form the MegaTrans complex in breast cancer. This is the first study to implicate the MegaTrans complex in contributing to the distinct biological trajectories of malignant and indolent ovarian cancer subtypes. | Differential gene expression identifies a transcriptional regulatory network involving ER-alpha and PITX1 in invasive epithelial ovarian cancer | 10.1186/s12885-021-08276-8 |
2021-07-02 | Background The co-transformation of solid waste of natural and anthropogenic origin can be carried out through solid-state-fermentation systems to obtain bio-products with higher added value and lower environmental impact. Methods To evaluate the effect of Pleurotus ostreatus on co-transformation of oxo-degradable low-density polyethylene (LDPE oxo ) sheets and lignocellulosic biomass (LCB), were assembled two 0.75 L microcosm systems in vertical (VMS) and horizontal (HMS) position. The pre-treated sheets with luminescent O 2 plasma discharges were mixed with pine bark, hydrolyzed brewer’s yeast and paper napkin fragments and incubated for 135 days at 20 ± 1.0 °C in the presence of the fungus. With the co-transformation residues, biochar (BC) was produced at 300 ± 1.0 °C (BC300) for 1 h, then used to carry out adsorption studies, using the malachite green dye (MG) at pH 4.0, 7.0 and 9.0 ± 0.2. Finally, the biochar was the substrate for the germination of carnation seeds ( Dianthus caryophyllus ) and Ray-grass ( Lolium sp.) in vitro. Results For HMS, the decrease in static contact angle (SCA) was 63.63% ( p = 0.00824) and for VMS 74.45% ( p = 0.00219), concerning the pristine. Plastic roughness in VMS was higher (26%) concerning the control. Throughout the 135 days, there were fungal growth and consequently laccase (Lac), manganese peroxidase (MnP) and lignin peroxidase (LiP) activities. During the first 75 days, CO 2 production increased to 4.78 ± 0.01 and 4.98 ± 0.01 mg g-1 for HMS and VMS, respectively. In MG adsorption studies, the highest amount of the colourant adsorbed at both pH 4.0 and 7.0 ± 0.2. Conclusions Finally, the biochar or the biochar enriched with low concentrations of plant growth-promoting microorganisms and inorganic fertilizer favours the germination of Dianthus caryophyllus and Lolium sp., seeds. | Evaluation of two microcosm systems for co-treatment of LDPEoxo and lignocellulosic biomass for biochar production | 10.1186/s40824-021-00222-w |
2021-07-02 | Background Maternal and newborn mortality is high immediately after childbirth and up to 42 days postnatally despite the availability of interventions. Postnatal care is crucial in preventing mortality and improving the health of women and newborns. This prospective cohort study investigated the initiation and utilization of postnatal care at health facilities and explored users’ and providers’ perspectives on utilization of postnatal care services. Methods A sequential explanatory mixed method was used involving women who were followed from the 3rd trimester of pregnancy to 3–4 months postnatally in Northwest, Tanzania. From January to December 2018, a door-to-door survey was conducted 3–4 months postnatally among 1385 of these women. A convenience sample of women and community health workers participated in focus group discussions, and traditional birth attendants and nurses participated in key informant interviews to complement quantitative data. Data analyses were conducted using STATA version 13 and NVIVO version 12. Study findings Approximately, one half of participants attended postnatal care within 42 days after delivery. Postnatal care seeking within 48 h after delivery was reported by 14.6 % of the participants. Women who attended antenatal care at least four times, delivered at health facilities or experienced delivery-related complications were more likely to seek postnatal care. Limited knowledge on the postnatal care services and obstetric complications after childbirth, and not being scheduled for postnatal care by health providers negatively influenced services uptake. Overwhelming workload and shortages of supplies were reported to hinder the provision of postnatal care services. Conclusions Utilization of postnatal care services remains low in this setting as a result of a number of disparate and complex factors that influence women’s choices. Provision of effective postnatal care is hindered by lack of supplies, staffing, and inadequate infrastructure. To ensure accessibility and availability of quality services in this setting, both demand and supply sides factors need to be addressed. | Late initiation and low utilization of postnatal care services among women in the rural setting in Northwest Tanzania: a community-based study using a mixed method approach | 10.1186/s12913-021-06695-8 |
2021-07-01 | To optimize the structure of the burner, improve the combustion performance, and reduce the emission of NO x , a self-circulating low NO x combustion technology was used to design a new type of flue gas self-circulating low NO x burner. Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO x emissions, the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method, and the burner operating parameters, such as preheating temperature and excess air coefficient, were deeply studied through the three-dimensional finite element numerical model in this paper. The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability. The optimal ejection coefficient was 0.4829. Overall, the amount of NO x emissions greatly increased from 6.23×10 −6 (volume fraction) at the preheating temperature 973 K to 3.5×10 −3 at preheating temperature 1573 K. When the excess air coefficient decreased from 1.2 to 1, the maximum combustion temperature decreased from 2036.3 K to 1954.22 K, and the NO x emissions decreased from 352.29×10 −6 to 159.73×10 −6 . | Effects of Optimized Operating Parameters on Combustion Characteristics and NOx Emissions of a Burner based on Orthogonal Analysis | 10.1007/s11630-020-1347-6 |
2021-07-01 | Fracture resistance of low- and medium-carbon steels depending on type of microstructure (ferritepearlite, bainite, and martensite) and its volume fraction is studied. On the basis of studying the temperature dependence for impact strength of V-notched samples and pre-cracked specimens the contribution of work for crack initiation and propagation to the general specific impact energy of steels with a different structural type is revealed. It is shown, that the main part of failure energy in low-carbon steels with ferrite-pearlite structure is work for crack initiation. For low-carbon martensite steels the work for crack initiation and propagation is comparable. Failure resistance of tempered low- and medium-carbon steels depending on the quantitative relationship of martensite, bainite and ferrite structures is described. Characteristic structural features of lower and upper bainite influencing fracture resistance are detailed. It is shown that failure resistance of such complex structures is governed by properties of the components, and also their amount and location. Polygonal ferrite, whose separation occurs mainly at the boundaries of previous austenite grains, has a particularly unfavorable effect on ductility properties and cold resistance. | Effect of High Strength Structural Steel Structural State on Fracture Resistance | 10.1007/s11015-021-01167-0 |
2021-07-01 | Abstract One of the applications of construction low-carbon 22K steels (AISI 1022 type) is used as a material for the body of a core catcher (CC) for nuclear power plants with water-cooled reactors (WCRs). In the event of a severe beyond design-basis accident, the CC vessel will be under conditions of prolonged high-temperature impacts, which can significantly change the structural state and lead to degradation of the mechanical properties of the vessel material. The data on the effect of such actions on the mechanical properties and fracture resistance of welds (its properties usually differ from those of the base metal) from low-carbon steels are very limited in the literature, which makes it difficult to guarantee the reliability and safety prediction of CC. The purpose of this work was to carry out comparative Charpy V-notch impact tests of samples of the base metal and the weld metal of the 22K steel welded joint before and after long-term high-temperature heat treatment, simulating the thermal effect in the conditions of a severe accident on the material of the NPP vessel. Welded joints of 22K steel sheets were obtained by the method of automatic argon-arc welding with a consumable electrode (welding wire SV-08G2S was used) in accordance with Rules and norms in nuclear industry PNAE G-7-009–89. Based on the test results, the ductile–brittle transition curves were plotted and the analysis of fracture of the samples was carried out. The influence of structural factors on the KCV impact toughness has been studied. It is shown that prolonged high-temperature exposure leads to an increase in the temperatures of the beginning and end of the ductile-brittle transition by 30–50°C and to an expansion by 15–25°C of the temperature range of the ductile-brittle transition of both the base metal and the weld metal of the welded joint. | Influence of Long-Term High-Temperature Action on the Impact Toughness of the Base Metal and the Weld Metal of the 22K Steel Welded Joint | 10.3103/S0967091221070068 |
2021-07-01 | In order to solve the problems due to the thickening of drilling fluids at low temperatures caused by the use of high-molecular-weight polymer coating agents in offshore deep-sea oil and gas drilling, a low-molecular-weight polymer coating agent named PADA was synthesized with acrylamide, methacryloxyethyltrimethyl ammonium chloride, and 2-acrylamido-2-methyl propane sulfonic acid. The PADA polymer was characterized with Fourier transform infrared spectroscopy and gel permeation chromatography. The shale inhibition effects of the PADA polymer and associated mechanisms were investigated by shale recovery and expansion experiments, transmission electron microscopy observation, particle size and zeta potential analysis, and interlayer spacing measurements. In addition, the effects of the coating agent on the filter cakes and the low temperature rheological properties of bentonite mud were also tested, and the polymer biodegradability was evaluated. The results showed that the molecular weight of the PADA polymer was 265,000 D, which was significantly lower than that of the traditional coating agents. The PADA had similar effects as two typical commercial products CAP and HPAM on inhibiting the hydration dispersion of shales and performed better than another product PAM. The inhibition effect was achieved by the polymer absorption onto the clay particles through both hydrogen bonding and the electrostatic interactions. The viscosity of bentonite mud containing PADA was much lower than that of mud with other coating agents at 4 °C, so the serious thickening caused by traditional coating agents at a low temperature could be avoided. In addition, it is relatively easily biodegraded. | Experimental investigation of a low-molecular-weight polymer coating agent for deep-sea oil and gas drilling | 10.1007/s13202-021-01198-y |
2021-07-01 | Aqueous Zn-based energy-storage devices have aroused much interest in recent years. However, uncontrollable dendrite growth in the Zn anode significantly limits their cycle life. Moreover, the poor low-temperature performance arising from the freezing of aqueous electrolytes at sub-zero temperatures restricts their practical applications in cold regions. Here, we fabricated low-temperature-tolerant and durable Zn-ion hybrid supercapacitors (ZHSCs) via modulating a co-solvent water/ethylene glycol electrolyte. The interaction of intermolecular hydrogen bonds between water and ethylene glycol as well as cation solvation was systematically investigated by tuning the co-solvent composition. The results illustrate that the ZnSO 4 /water/ethylene glycol (65%) electrolyte possesses high ionic conductivity at low temperatures and effectively prevents the dendrite formation of the Zn anode. The as-fabricated ZHSCs exhibit long-term cyclability and are capable of working at sub-zero temperatures as low as −40°C. The present ZHSCs are anti-freezing and cost-effective, which may find new applications in the fields of next-generation electrochemical energy storage devices. 近年来, 水系锌基储能器件引起了人们极大的关注. 然而, 锌负极中不可控的枝晶生长限制了其循环寿命. 另外, 水系电解液在零度以下冻结导致较差的低温性能, 限制了其在寒冷地区的实际应用. 以锌离子混合电容器为例, 本文报道了通过调节水/乙二醇共溶剂电解液来构建耐低温、 长寿命的锌离子混合电容器. 通过调控共溶剂的组分, 系统探索了水和乙二醇分子间的氢键作用以及阳离子溶剂化对电化学性能的影响. 结果表明, 硫酸锌/水/乙二醇(65%)电解液在低温下具备较高的离子电导率, 并且可以有效地防止锌负极中枝晶的形成. 组装的锌离子混合电容器具有长循环稳定性, 能够在零下40°C的极端低温条件下工作. 该锌离子混合电容器成本低, 具有较好的抗冻特性, 有望应用于下一代电化学储能领域. | Fabricating low-temperature-tolerant and durable Zn-ion capacitors via modulation of co-solvent molecular interaction and cation solvation | 10.1007/s40843-020-1570-5 |
2021-07-01 | Application of bio-based diisocyanates with low volatility instead petrochemical diisocyanates has positive impact on environment by reduction of hazardous effects on living organisms and lead to bio-based polyurethanes (bio-PUs) with good usage properties. This work was focused on the synthesis and chosen properties examination of partially bio-based thermoplastic polyurethane elastomers (bio-PUs) obtained using diisocyanate mixtures, polytetrahydrofurane (PolyTHF) and bio-1,3-propanediol (bio-PDO). Two types of diisocyanate mixtures were prepared as follows: aliphatic–aliphatic based on hexamethylene diisocyanate with partially bio-based aliphatic diisocyanate Tolonate™ X FLO 100 (HDI-FLO) and aromatic–aliphatic based on diphenylmethane diisocyanate with partially bio-based diisocyanate (MDI-FLO) with reduction of 25 mass% of petrochemical diisocyanate. Bio-PUs were obtained via prepolymer method. Thermoplastic polyurethane elastomers have been examined in the terms of chemical structure and thermal, thermomechanical, mechanical and physicochemical properties. Bio-PU based on HDI-FLO diisocyanate mixture exhibited higher thermal stability. The beginning of thermal decomposition took a place at lower temperature ca. 30 ºC) and lower rate than the MDI-PU based materials. DMA analysis showed that HDI-FLO based polyurethanes exhibited greater capacity to accumulate energy and higher stiffness. Both materials characterized similar tensile strength and hardness, but with difference that TPU based on HDI-FLO relieved greater elongation at break about 360% reached 813%. Taking into account versatile properties of bio-TPU, these material can find application in many branches of industry. | Eco-friendly Route for Thermoplastic Polyurethane Elastomers with Bio-based Hard Segments Composed of Bio-glycol and Mixtures of Aromatic–Aliphatic and Aliphatic–Aliphatic Diisocyanate | 10.1007/s10924-020-01992-5 |
2021-07-01 | In recent years, the excess discharge of ammonia nitrogen from wastewater into surface water has been regulated by more stringent standard. The air stripping method is successfully used to treatment of high-concentration ammonia nitrogen; however, alkali will be added to keep pH more than 10, which is costly and not environment-friendly operation. In this study, an advanced air stripping (AAS) based on foam separation of removing ammonia nitrogen in low concentration from aqueous solution at low pH was proposed. The effect of conditions such as air flow rate, temperature, SDS dosage, coexisting ionic strength, pH, and initial ammonia nitrogen concentration on the removal efficiency was studied. The advanced air stripping exhibited favorable removal efficiency for NH 4 + -N in low concentration from aqueous solution (20 mg·L −1 ) with a broad range of low pH 3.0–9.0. Besides, for strongly alkaline (pH=11.0) solution, the advanced air stripping can alleviate the decrease of pH to some extent and keep ammonia nitrogen stripping out continuously based on equilibrium shift between NH 4 + and NH 3 . A microcalorimeter was applied to demonstrate the interaction between the negatively charged hydrophilic groups of SDS and NH 4 + ions, helping to understand the mechanisms more clearly. The simple operation and the satisfactory removal efficiency could imply that the advanced air stripping is a promising technology for minimizing low-concentration NH 4 + -N. Graphical abstract | Significant removal of ammonia nitrogen in low concentration from aqueous solution at low pH by advanced air stripping | 10.1007/s11356-021-13164-6 |
2021-07-01 | Copolymers and blends of polyhedral oligomeric silsesquioxane (POSS) and polyimides have been shown to resist atomic-oxygen (AO) attack, making them promising candidates as space-durable materials in the harsh oxidizing environment of low Earth orbit (LEO). CORIN ® is a commercially available and colorless POSS–polyimide which has the desirable but uncommon property among polyimides that it may be dissolved in a solvent and applied at room temperature, thus making it possible to have a widely applicable clear coating for protection from AO in LEO. The physical properties of CORIN ® have been largely characterized, but its AO resistance has received limited study. We have thus used a hyperthermal AO beam to expose CORIN ® and other POSS-containing polyimides, 7.3 wt% and 9.1 wt% Si 7 O 9 trisilanolphenyl POSS blended with poly(pyromellitic dianhydride- co -4,4′-oxydianiline), to characterize their resistance to AO attack. CORIN ® was found to have a particularly low erosion yield that is ≲1% that of the ubiquitous satellite material, Kapton, which agrees favorably with a result from an experiment on the International Space Station. The other POSS-containing polymers exhibited somewhat higher erosion yields of 1.4 and 2.2% that of Kapton, respectively. Surface characterization of CORIN ® showed that it remained relatively smooth during AO exposure and implied that a passivating silicon oxide was formed. The comparison of the AO effects on CORIN ® and the other POSS–polyimides suggests that the net effect of AO on such POSS–polyimides depends on the density of Si atoms as well as the reactivity of the organic component of the polymer. This work adds to our confidence in the use of POSS-containing polymers in LEO and, especially, in very LEO, where the necessity of protecting satellite materials and components from AO attack is critical. | POSS-enhanced colorless organic/inorganic nanocomposite (CORIN®) for atomic oxygen resistance in low earth orbit | 10.1007/s12567-021-00347-7 |
2021-07-01 | Abstract A mold steel for plastic injection was subjected to low cycle fatigue (LCF) tests at temperatures of 25, 200, and 250 °C. LCF tests were carried out at a total strain amplitude ( Δε t /2) from 0.004 to 0.012 under a constant strain rate of 0.01 s –1 . Transmission electron microscope images showed that cyclic loading accelerated dislocation recovery as the LCF test temperature increased. The LCF life increased as a result of improvement in the ductility associated with dislocation recovery as the test temperature increased. The LCF behavior at the test temperature range followed the Coffin–Manson equation. Empirical equation was proposed to predict the LCF life of the mold steel within the test temperature range. Graphic Abstract Empirical equation was proposed to predict the LCF life of the mold steel considering the total strain amplitude and test temperature, and the calculated LCF life was in good agreement well with the experimental results. | Effects of Test Temperature on Low Cycle Fatigue Behaviors in Large Mold Steel | 10.1007/s12540-020-00760-3 |
2021-07-01 | Experience of structure development, manufacture, and testing of a pneumatic pressure shell accumulator with a volume of 25 dm 3 is presented. A binder composition for “cold” hardening based on ÉD-20 epoxy resin and Étal-23X cycloaliphatic amine is developed. In terms of rheological and physicomechanical properties the binder proposed is suitable for manufacturing shells by a “wet” winding method with low energy consumption for hardening. | Development of a Polymer Composite Material with an Epoxy Binder for Producing a High-Pressure Cylinder | 10.1007/s10556-021-00940-x |
2021-07-01 | Recently, the modification of bituminous binders is an ongoing trend. However, most current analytical methods are insufficient to characterize bitumen. Generally, standardized laboratory techniques are often time and cost consuming. Moreover, they use one-purpose devices requiring a considerable amount of samples and solvents. Therefore, we investigated three special instrumental analytical techniques to find out bitumen properties. Our main objective was to obtain some additional parameters of bituminous binders to allow their more accurate description. The first studied method, thermogravimetric analysis operated especially in a high-resolution mode that can be used as a fingerprint area in spectrometry to determine the bitumen quality. The second one modulated differential scanning calorimetry provided many various important parameters, including temperature of glass transition, cold crystallization and serviceability limit state. The third one, the thermomechanical analysis also measured the value of glass-transition temperature for comparison with the method mentioned above. We have found correlations between the results from thermal instrumental techniques and standardized laboratory tests. | Using various thermal analytical methods for bitumen characterization | 10.1007/s42947-020-0157-2 |
2021-07-01 | In this study, LaFeO 3 photocatalyst had been synthesized via a gel combustion method using glucose and citric acid as dual chelating agents. Furthermore, the effect of different calcination temperatures (400 °C, 500 °C and 600 °C) on the physicochemical properties of the synthesized LaFeO 3 were also investigated. From the study, LaFeO 3 nanoparticles calcined at 400 °C were selected as the most promising photocatalyst due to their amorphous nature which benefits from the presence of a surface defect. In addition, the amorphous LaFeO 3 also recorded the highest surface area with a value of 70.02 m 2 /g which contributed to the enhancement of photocatalytic activity for the degradation of humic acid (HA). Besides that, effect of operational parameters such as photocatalyst loading (0.6–1.20 g/L), initial concentration of HA (10–40 mg/L) and aeration (presence of oxygen) for HA degradation under visible light irradiation was studied using the amorphous LaFeO 3 . Overall, the optimal values for degradation of HA were observed at a catalyst loading of 1.0 g/L and initial concentration of 10 mg/L. In a nutshell, the perovskite-based photocatalyst was successfully synthesized where the amorphous LaFeO 3 outperformed the crystalline LaFeO 3 as regards higher reaction rate constant 0.0305 min −1 (amorphous; 400 °C) compared to 0.0250 min −1 (crystalline; 500 °C) and 0.01329 min −1 (crystalline; 600 °C), respectively. | Impacts of Annealing Temperature on Morphological, Optical and Photocatalytic Properties of Gel-Combustion-Derived LaFeO3 Nanoparticles | 10.1007/s13369-020-04874-z |
2021-07-01 | In this study, a low-temperature planar solid electrolyte oxygen generator (SEOG) based on a (Bi 1.50 Y 0.50 ) 0.98 Zr 0.04 O 3+δ (BYO)/Bi 1.71 Nb 0.25 Ba 0.04 O 3+δ (BBNO) dual-layer electrolyte membrane was developed. The SEOG device consisted of a Ag (10 µm)/BBNO (13 µm)/BYO (710 µm)/BBNO (13 µm)/Ag (10 µm) cell sandwiched between a pair of modular planar SUS 316 interconnects with a web-type gas flow channel using a ZnO-SiO 2 -Al 2 O 3 glass sealant. The BYO layer had high oxygen-ion conductivity at low temperatures, while the BBNO layer provided good adhesion to the high-fire Ag electrode. The leakage value of the SEOG device tested at an operating temperature of 550°C was less than 0.005 (standard cubic centimeters per minute) sccm/cm. The device had excellent hermetic performance and mechanical integrity, thereby verifying the feasibility of the SEOG configuration. The oxygen flux produced by the SEOG device linearly increased with current density, reaching 0.72 cm/min at a current density of 0.20 A/cm 2 , slightly deviated from the Faraday relation at 0.25 A/cm 2 , and then began to level off beyond 0.25 A/cm 2 . The Faradaic efficiency of the device was 96.3% at up to 0.20 A/cm 2 and dropped rapidly to 66.6% at 0.37 A/cm 2 . The rapid degradation of the oxygen production at high current density was caused by the reduction of the BYO/BBNO electrolyte and the concentration polarization at the electrodes. As the applied voltage driving the current density was higher than the BYO/BBNO decomposition voltage of 0.58 V at 550°C, it triggered the instability of the Ag/BBNO/BYO/BBNO/Ag cell and thus, that of the SEOG device. | Low-Temperature Planar Oxygen Generator with (Bi1.50Y0.50)0.98Zr0.04O3+δ/Bi1.71Nb0.25Ba0.04O3+δ Dual-Layer Electrolyte Membrane | 10.1007/s11664-021-08874-z |
2021-07-01 | To long-term immobilization of secondary iodine-waste, iodine loaded silver-coated silica-gel (AgIs), glass-powder was used to directly solidify AgIs at low temperature. B 2 O 3 -Bi 2 O 3 -ZnO-SiO 2 was used as raw materials to manufacture the glass-matrix under different temperature. The samples with the richest glass phase were obtained at 1000 °C, and were used to solidify AgIs with different content of I − . The sample with 30 wt % I − possessed the highest amorphous index (0.62) at 600 °C. Element I was uniformly distributed, and the density reached to 3.06 g/cm 3 . This work highlights a simple way to solidify secondary iodine-waste at low temperature. Graphic abstract | Direct immobilization of iodine-loaded silver-coated silica gel with silicate glass powders at low temperature | 10.1007/s10967-021-07765-1 |
2021-07-01 | The influence of finish rolling and accelerated cooling stages on structure and property formation for low-manganese steel under laboratory conditions is studied. Rolling ends at temperatures in both the γ-region and at various temperatures in the γ + α -region. Accelerated cooling completion temperature is varied in the range of 630–350°C. Comprehensive analysis of the microstructure, crystallographic texture, and fine structure parameters of laboratory rolled specimen is performed. Specific features of structure and property formation are studied and compared with known pipe steels. The range of rolling parameters providing an optimum combination of strength, toughness, and cold resistance is determined. | Formation of Structure and Properties of Low-Carbon Pipe Steel with Ultralow Manganese Content during Thermomechanical Treatment | 10.1007/s11015-021-01180-3 |
2021-07-01 | Temperature control is a critical factor in PCR for efficient DNA amplification. The main aim is to achieve tight control and high rate of heating and cooling for a portable, cost-effective PCR device. This speed depends on reduction of the thermal mass of the PCR heating part. The common methods used to decrease the device's thermal mass or heating/cooling time are to improve desirable device structural design and to choose a better heating and cooling mechanism with robust controller. Increasing the thermal mass provides a good temperature distribution on the heater surface, but it delays the heat transfer. Therefore, removing thermal mass makes the controller struggle to provide a high temperature uniformity distribution on Peltier surface. In this paper, we provide a cost-effective PCR heating/cooling system using Peltier element. This system is controlled using adaptive FLC with bang-bang as a hybrid controller to provide good accuracy with maximum available temperature changing rate. The results show that in cooling, the adaptive FLC with bang-bang controller is faster by 20 % than the normal PD-like FLC, however in heating it is faster by 5 to 10 %. The adaptive FLC provided steady state error 3 % and 1.5 % less than the normal FLC at denaturation and annealing steps, respectively. Temperature distribution is tested using thermal camera. The device is validated by performing conventional PCR. The amplification product was analyzed by electrophoresis on a 1.5 % agarose gel then stained with ethidium bromide and the products show successfully amplified. | New cost effective design of PCR heating cycler system using Peltier plate without the conventional heating block | 10.1007/s12206-021-0646-5 |
2021-07-01 | Purpose This paper aims to review the evidence comparing low-speed drilling without irrigation versus conventional drilling for dental implant osteotomy preparation. Materials and methods A systematic review was carried out based on the PRISMA statement. Four databases and gray literature were searched up to November 2020. In vitro, animal, and clinical studies were included. The variables were temperature change, drilling time, quantity of harvested bone, osteotomy precision, marginal bone loss, implant success rate, osseointegration, and the histomorphologic characteristics and cellularity of the osteotomy and of the harvested bone. Different tools for the assessment of bias were applied for each study design. Results A total of 626 articles were identified, of which 13 were included. Both low-speed drilling without irrigation (test group) and conventional drilling (control group) maintained temperatures below the critical temperature of 47 °C. The test group yielded a greater quantity and more beneficial cellular and histomorphologic properties of harvested bone, with a longer drilling time and greater osteotomy precision ( p < 0.05). No significant results were obtained regarding drill wear, osseointegration, marginal bone loss, implant success rate, and histomorphology of the dental implant osteotomy ( p > 0.05). The results, in particular on the osteotomy precision and quantity of harvested bone chips, should be interpreted with caution because outcomes are based in only one in vitro study. Conclusions Low-speed drilling without irrigation seems to be comparable to conventional drilling in preparing dental implant osteotomies. In some situations, low-speed drilling without irrigation might offer advantages over conventional drilling. The results should be interpreted with caution due to the low percentage of clinical human studies. Accordingly, more clinical studies are needed to improve the scientific evidence on this topic. Clinical relevance The low-speed drilling without irrigation is a valid technique for dental implant osteotomy preparation. Its higher quantity and quality of harvested autologous bone might be particularly beneficial in cases of dental implant placement with minor simultaneous bone regeneration. | Low-speed drilling without irrigation versus conventional drilling for dental implant osteotomy preparation: a systematic review | 10.1007/s00784-021-03939-z |
2021-07-01 | In this study, wire arc additive manufacturing process is employed to fabricate a low-carbon low-alloy steel block, using an ER70S-6 solid wire. Three sets of samples with different orientations, including perpendicular (Vertical), parallel (Horizontal), and 45° (45-degree) relative to the deposition plane, were prepared in order to investigate the anisotropy in mechanical properties and microstructure of the fabricated part. Both Horizontal and 45-degree samples showed a uniform microstructure containing mostly ferritic grains with a small volume fraction of pearlite at their grain boundaries. Differently, a periodic microstructure was detected in the Vertical sample, consisting of a combination of acicular ferrite, bainite, and allotriomorphic ferrite formed in the interlayer regions in addition to polygonal ferrite within the melt pools’ center. Moreover, the uniaxial tensile and Charpy impact results exhibited isotropic tensile, yield, elongation, and impact properties for both Horizontal and 45-degree samples; however, the Vertical sample showed a lower mechanical performance. The improved mechanical properties of the Horizontal and 45-degree samples were correlated to their uniform ferritic microstructure. | On Microstructure and Mechanical Properties of a Low-Carbon Low-Alloy Steel Block Fabricated by Wire Arc Additive Manufacturing | 10.1007/s11665-021-05568-9 |
2021-07-01 | In this study, the low cycle fatigue behavior and failure mechanism of WAAM 16MND5 bainitic steel, which is commonly used in the nuclear reactor, were investigated thoroughly via a series of strain-controlled and stress-controlled low cycle fatigue tests. Results show that the microstructure of WAAM 16MND5 steel is granular bainite with a certain number of banded pro-eutectoid ferrite. WAAM 16MND5 steel exhibits similar cyclic deformation behavior under different strain amplitudes, i.e., a long stage of continuous cyclic softening and rapid cyclic softening till failure. The fatigue life decreases with the increasing strain amplitude. Moreover, the persistent slip markings in ferrite grains, the interface of pro-eutectoid ferrite and large Al 2 O 3 inclusions are the preferred locations for microcrack initiation. The crack initiated from the edge of the specimen is observed to develop into a main crack. The main crack propagates mainly in transgranular mode and can also propagate along the pro-eutectoid ferrite interface. | Low Cycle Fatigue Behavior and Failure Mechanism of Wire Arc Additive Manufacturing 16MND5 Bainitic Steel | 10.1007/s11665-021-05554-1 |
2021-07-01 | Abstract Chloroplast ultrastructural changes were investigated in chilling-sensitive (cucumber, Cucumis sativus L.) and cold-tolerant (winter rye, Secale cereale L.) plants during low-temperature hardening. Cold hardening was found to shorten the total length of thylakoid membranes in chloroplasts of both species by 20–30%. The reduction in total membrane length in cucumber was due to the decline in membrane length of both grana and stroma thylakoids, whereas the membrane length of grana thylakoids in winter rye was reduced without changes in length of stroma thylakoid membranes. In cucumber plants, the chloroplast section area decreased during hardening in parallel with more than threefold increase in starch grain area. In winter rye, the chloroplast area increased after hardening, while starch grains were completely absent. Both S. cereale and C. sativus retained photosynthetic activity at hardening temperatures, although photosynthetic rates decreased by 2–3 times compared to those in untreated plants. The content of soluble sugars in leaves increased by 20% in cucumber and increased more than threefold in winter rye. The accumulation of starch in cucumber chloroplasts provides evidence that a significant part of photosynthetic products was removed from the osmotic pool, which limited the efficiency of hardening in C. sativus plants. In winter rye plants, the thylakoid system rearrangement and the lack of starch synthesis in chloroplasts caused a severalfold increase in the content of intracellular soluble sugars, which ensured highly efficient low-temperature hardening of these plants. | Ultrastructural Changes in Chloroplasts of Cucumis sativus L. and Secale cereale L. during Low-Temperature Hardening | 10.1134/S1021443721040130 |
2021-07-01 | In this work, a novel approach of leaching valuable metals, such as niobium, yttrium and cerium, from a niobium-bearing ore of low grade by roasting KHSO 4 –H 2 SO 4 system was experimentally studied. Through the work, the effects of roasting temperature, roasting time, mass ratio of agents to ore and the types of leaching agents on the extraction of Nb, Y and Ce were investigated, and the roasting KHSO 4 –H 2 SO 4 –ore system was thought as an effective method to extract these valuable metals. It was found that the recovery of Nb, Y and Ce can, respectively, reach 90.20%, 97.22% and 98.41% in condition of roasting temperature of 300 °C, roasting time of 2 h, mass ratio of KHSO 4 -to-H 2 SO 4 to ore of 0.5:1:1, particle size of − 74 μm (~ 95%), leaching solution of oxalic acid (30 g·L −1 ), leaching temperature of 90 °C and leaching liquid-to-solid ratio of 5:1. The leaching kinetics of the calcined Nb-bearing ore in oxalic acid solution was successfully modeled by chemical reaction model, and the apparent activity energy was obtained to be 14.16 kJ·mol −1 . The results generated from this work will provide the fundamentals for extracting Nb, Y and Ce from a niobium-bearing ore of low grade and have potential applications value in future. | A novel approach to extract Nb, Y and Ce from a niobium-bearing ore of low grade by roasting KHSO4–H2SO4 system | 10.1007/s12598-020-01435-z |
2021-07-01 | The main aim of our paper is to analyze the influence of temperature and service time on the fracture resistance of welded joint constituents for new and exploited low-alloyed A-387Gr.B steel (Cr–Mo type) under the action of dynamic load and changes in the mechanical properties. The exploited parent metal, as a part of the reactor mantle, is in the damage repair stage, i.e., a part of its mantle is replaced with a new material. Wohler’s curves were constructed, i.e., the fatigue strength as material resistance to crack initiation, was determined at the room and working temperatures. Testing of the welded joint and microstructural analyses of the parent metal, weld metal, and the heat-affected zones were carried out. Based on the testing results, the analysis of the fracture resistance, and the microstructural changes, represent the comparison of values obtained for the characteristic areas of the welded joint and the justification of the selected technology of welding. | Influence of Temperature and Operation Time on the Fatigue Strength and Microstructure of Welded Joints of A-387Gr.B Steel | 10.1007/s11003-021-00518-1 |
2021-07-01 | Abstract Nanocrystalline ceramic samples of the ZrO 2 –3 mol % Y 2 O 3 composition with varying degrees of tetragonality c / a (1.4337 and 1.0425) are obtained. The process of the low-temperature degradation of ceramics is studied by the methods of X-ray phase analysis and electron microscopy. It is found that samples with a high degree of tetragonality are more resistant to the action of a humid environment, while the phase composition in the bulk of the samples remains practically unchanged and the transformation t -ZrO 2 → m -ZrO 2 occurs mainly in the surface layers without significantly affecting the mechanical properties of the ceramics. | Obtaining ZrO2–3 mol % Y2O3 Ceramics with Various Degrees of Tetragonality and Studying Low Temperature Degradation | 10.1134/S108765962104009X |
2021-07-01 | Abstract This work is aimed at developing homogeneous, uniformly distributed fine-crystalline coatings based on triclinic octacalcium phosphate pentahydrate (OCP, Ca 8 H 2 (PO 4 ) 6 ⋅5H 2 O) on the surface of ceramic substrates made of hydroxyapatite (HA, Ca 10 (PO 4 ) 6 (OH) 2 ). The process of the crystalline layer of low-temperature calcium phosphates consists in a partial dissolution and recrystallization of surface layers of ceramic substrates through the intermediate phase of dicalcium phosphate dihydrate (DCPD, CaHPO 4 ⋅2H 2 O). A buffer solution having an increased concentration of $${{{\text{H}}}_{{\text{2}}}}{\text{PO}}_{4}^{ + }$$ and $${\text{HPO}}_{4}^{{2 + }}$$ anions and containing Ca 2+ ions is proposed for surface modification. When creating the crystalline coating, the buffer solution partly dissolves the surface layers, and the coating with the required phase composition and morphology is formed upon reaching the necessary concentration of Ca 2+ ions on the solution–ceramic interface. To obtain a uniform coating, Ca 2+ ions are gradually added to the buffer solution. The conditions of the beginning of the dissolution of calcium phosphate ceramic substrates and the thermodynamic conditions of the formation of uniform OCP-based coatings are established. | Coatings of Low-Temperature Calcium Phosphates on Hydroxyapatite Ceramic | 10.1134/S207511332104016X |
2021-07-01 | Abstract Characteristics of organosilicon sealant of VGO-1 brand, which is employed in the preparation of glue-welded joints through contact welding are considered. Preparation conditions of glue-welded joints are given and it is determined that there is a decrease in the magnitude of welding current and an increase in the time of welding and electrode contact pressure upon welding of steel specimens of 08kp brand by the VGO-1 sealant. Structural studies of the sealant after exposure at various temperatures show that the sealant possesses high frost resistance at –30°C in the air and a satisfactory frost resistance at –50°C in the liquid. The swelling degree of the sealant after 20 days of exposure in medical ethyl alcohol is less than 4.5%. | Evaluation of Frost Resistance of Organosilicon Sealant at Ultralow Temperatures | 10.1134/S1995421221030138 |
2021-07-01 | The rational design of polymer acceptors with strong and broad absorption is critical to improve photovoltaic performance. In this work, a new polymer acceptor PY9-T based on heptacyclic benzotriazole (Y9-C16) as a building block and thiophene unit as the linking unit was synthesized, which exhibited a low bandgap (1.37 eV) and a high extinction coefficient of the neat film (1.44×10 5 cm −1 ). When PY9-T was blended with the wide bandgap polymer donor PBDB-T, the all-polymer solar cells (APSCs) showed a high power conversion efficiency (PCE) of 10.45% with both high open circuit voltage of 0.881 V and short-circuit current density of 19.82 mA/cm 2 . In addition, APSCs based on PY9-T show good thermal stability, as evidenced by slight changes morphologies when annealed at 100 °C. These results suggest that Y9-C16 provides a new building block to develop efficient and stable polymer acceptors. 合理设计具有强和宽吸收的聚合物受体有助于提高光伏性能。本文以七环苯并三氮唑(Y9-C16) 为构筑单元,噻吩为连接单元合成一个新型聚合物受体材料PY9-T。该受体材料的薄膜具有较低的带 隙(1.37 eV)和较高的消光系数(1.44×105 cm −1 )。当PY9-T 与宽带隙聚合物给体PBDB-T 共混时,制备 全聚合物太阳电池(APSC)实现10.45%的高能量转换效率,器件具有0.881 V 的高开路电压和 19.82 mA/cm 2 的高短路电流密度。此外,器件在100 °C 退火后,共混膜形貌仅发生微小的变化,表明 APSC 具有好的热稳定性,Y9-C16 为开发高效稳定的聚合物受体提供了新的构筑单元。 | A new low-bandgap polymer acceptor based on benzotriazole for efficient all-polymer solar cells | 10.1007/s11771-021-4741-7 |
2021-07-01 | Abstract — This article presents the experimental results of wear resistance of elastomeric composites based on butadiene–nitrile rubber BNKS-18 containing hollow corundum microspheres HCM-S and HCM-L at +22°C and –34°C. It has been demonstrated that introduction of the corundum microspheres into the rubber mixture leads to a decrease in abrasion of elastomeric composite upon friction both at +22°C and at –34°C. SEM has revealed the features of wear of elastomeric composite at various temperatures of abrasive friction. In particular, it has been demonstrated that, contrary to friction at–34°C, upon friction at +22°C the abrasive wear mechanism is accompanied by friction wear. It has been revealed that upon abrasive impact at –34°C there occurs more intensive destruction of walls of corundum microspheres due to a decrease in elasticity and increase in elastomer rigidity leading to increase in closeness of contact between corundum microspheres and abrasive solid particles occur. The types of their destruction are proposed depending on the position in the elastomeric matrix. The first type, when the larger part of the microsphere is located inside the rubber and only the smaller part of the top is visible, which is exposed to destruction. The second type of destruction is observed when the position of microsphere in the rubber is shallower and it protrudes from the rubber by about 50%, thus, the microsphere is exposed to severe destruction. The destroyed cavity of such microspheres is clogged with worn rubber and abrasive. The third type of destruction is observed when the larger part of the microsphere protrudes from the rubber and a crater is formed instead of it. | The Features of Abrasive Wear of Elastomeric Composite with Corundum Microspheres at Low Temperatures | 10.3103/S1068366621040115 |
2021-07-01 | The structure of copper species, dispersed on nanostructured ceria (particles, rods and cubes), was analyzed by scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS). It was interestingly found that the density of surface oxygen vacancies (or defect sites), induced by the shape of ceria, determined the geometrical structure and the chemical state of copper species. Atomically dispersed species and monolayers containing few to tens of atoms were formed on ceria particles and rods owing to the enriched anchoring sites, but copper clusters/particles co-existed, together with the highly dispersed atoms and monolayers, on cubic ceria. The atomically dispersed copper sites and monolayers interacted strongly with ceria, involving a remarkable charge transfer from copper to ceria at their interfaces. The activity for the low-temperature water-gas shift reaction of the Cu/CeO 2 catalysts was associated with the fraction of the positively-charged copper atoms, demonstrating that the active sites could be tuned by dispersing Cu species on shape-controlled ceria particles. | Atomically dispersed copper species on ceria for the low-temperature water-gas shift reaction | 10.1007/s11426-020-9867-x |
2021-07-01 | Abstract The practical aspect of nanotechnology includes the production of devices and their components needed to create, process and manipulate atoms, molecules and nanoparticles. The phenomena of aging and self-heating significantly affect the operation of microelectronic circuits. This paper developed a model of a three-bit, parallel analog-to-digital converter with low power consumption, as a result of which the circuit does not use resistors and comparators. The absence of resistors improves the static power consumption of the circuit and reduces the problems associated with aging and self-heating, while the absence of comparators has a positive effect on the dynamic power consumption. The Parallel A/D converter has been designed for a 14 nm process, at 25°C, for input signals with an amplitude of 1.8 V. The results obtained show that the developed converter uses about 100 times less energy compared to the classical architecture. Since the eight resistors were removed from the circuit, the area of the resulting converter was reduced by at least 8 R nom , where R nom = 0.7225 μm is the area of the 1 KΩ resistor. | Low Power Analogue-Digital Converter Model | 10.3103/S1068337221030178 |
2021-07-01 | Abstract The cooling of rock formations when extracting heat by a borehole heat exchanger and the restoration of the thermal field in the rock during the idle time of the well have been investigated. The heat in the rock during the summer downtime of the well is partially restored due to the influx of heat from the outside formation. The radius of the rock cooling front around the borehole in the heating period can reach 6–8 m. The temperature on the borehole wall is restored by approximately 50% in one month and by 80–85% in summer. Hybrid technology is proposed for the extraction and accumulation of thermal energy from the upper layers of the earth’s crust comprised of a shallow borehole heat exchanger, a heat pump, and solar collectors. The technology provides for both the extraction of heat from the rock during the heating period and transmission of this heat to the heating system with a heat pump and the restoration of the temperature field around the well during the interheating period by accumulating in the rock formation the heat fed to the borehole heat exchanger with hot water from the storage tank. This system was implemented in Makhachkala at the test site of the Joint Institute for High Temperatures, Russian Academy of Sciences, for supplying heat and hot water to cottage-type houses. The main components of the system are solar collectors with a total area of 20 m 2 , a heat-insulated hot water storage tank with a built-in heat exchanger, a 15-kW heat pump, and a 100-m deep borehole heat exchanger. The test results have demonstrated high efficiency of the system for supplying heat to low-power consumers not covered by central heating. | A Hybrid Solar–Geothermal Heat- and Hot-Water Supply System | 10.1134/S0040601521050025 |
2021-07-01 | Concerning the increased market for bio-based materials and environmentally safe practices, cellulose-based beads are one of the more attractive alternatives. Thus, this work focuses on the generation of functional cellulose-based beads with a relatively simple and direct method of blending a pre-modified chitosan bearing the targeted functional groups and cellulose, prior to the formation of the beads, as a mean to have functional groups in the formed structure. To this end, chitosan was chemically modified with propargyl bromide in homogenous reaction conditions and then combined with cellulose in sodium hydroxide/urea solution and coagulated in nitric acid to produce spherical shaped beads. The successful chemical modification of chitosan was assessed by elemental analysis, as well as by Fourier-transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The alkynyl moieties from the chitosan derivative, served as reactive functional groups for click-chemistry as demonstrated by the tagging of the commercial fluorophore Azide-Fluor 488 via CuI-catalysed alkyne-azide cycloaddition reaction, in aqueous media. This work demonstrates the one-step processing of multiple polysaccharides for functional spherical beads as a template for bio-based scaffolds such as enzyme immobilization for stimuli-response applications and bioconjugations. | Simple functionalization of cellulose beads with pre-propargylated chitosan for clickable scaffold substrates | 10.1007/s10570-021-03905-8 |
2021-07-01 | Abstract A mathematical model of oxygen–methane plasma combustion at pressures of 0.2−1.6 MPa has been developed with allowance for the ionization of combustion products and recombination of charged components. Positive ion concentrations in characteristic zones of the reacting oxygen–methane mixture are estimated under the assumption of ambivalent diffusion. Distributions of self-consistent electric field and generated electric charge along the channel are determined. Results of modeling of the levels of electron and ion concentrations in the flame agree with the well-known experimental data obtained by probe methods under operation conditions of a model liquid-propellant rocket engine. | Features of Intrinsic Electric Field Formation in Low-Temperature Oxygen–Methane Plasma | 10.1134/S1063785021050278 |
2021-07-01 | Growing evidence has suggested the feasibility and effectiveness of blood coagulation with low temperature plasma (LTP) at atmospheric pressure. In the present study we examined morphological changes and contents released out from platelet after LTP treatment to investigate the mechanism of LTP accelerate blood coagulation. Changes of isolated rat platelets treated with LTP had been detected by flow cytometry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additionally, a scheme that the mixture of different color fluorescent stained platelets treated by LTP and then detected by flow cytometry had proposed to quantitatively assess plasma triggered platelets aggregation. Furthermore, we had used label free quantitative mass spectrometry to identify changes in the supernatant proteome released from LTP treated platelets. On the surface of LTP treatment hastened whole rat blood clots, a layer of semi-transparent film had formed, which had been demonstrated to form from platelet-like membrane structure by ultrastructural analysis with TEM. Flow cytometry combined with fluorescent staining confirmed that LTP treatment promoted platelet aggregation. The observation of plasma treated stained platelets under fluorescence confocal microscopy also confirmed this judgment. We separated the supernatant from the platelets treated with LTP, and then analyzed their differences using mass spectrometry. Compared with control group, Gene ontology (GO) analysis showed that the concentration of 16 protein molecules in the experimental group was increased. LTP treatment can promotes platelet aggregation and the release of platelet activating proteins, which is the potential mechanism of speeding up blood coagulation. | Low Temperature Plasma Treatment of Rat Blood is Accompanied by Platelet Aggregation | 10.1007/s11090-021-10176-5 |
2021-07-01 | The microstructure and corrosion behavior of friction stir (FS) welded API X-60 pipeline steel were investigated. Three FS welds were successfully fabricated under various welding conditions using a tungsten carbide-base tool. It was found that the microstructure and corrosion performance of the welds were strongly affected by welding parameters. A thermal history study of the welds showed that all stir zones heated up to the temperature of the ferrite–austenite region. Electron backscatter diffraction (EBSD) characterizations revealed that a significant grain refinement in the stir zones was accompanied by the formation of low angle grain boundaries. The kernel average misorientation analyses showed that the amount of residual strain and dislocation density were increased after welding. The corrosion assessments using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements showed that the welds exhibited superior corrosion resistance than that of the base metal. There results were confirmed according to the immersion tests. | Microstructure and Corrosion Properties of Friction Stir-Welded High-Strength Low -Alloy Steel | 10.1007/s12666-021-02219-4 |
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