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2020-08-01 | The need to increase electrification in the automotive industry has been well recognized. Overshadowed by their larger counterparts used for the car’s traction is the increasing number of small electric drives used in automotive applications. As a matter of fact, up to 100 of such drives are used within a typical mid-sized car. This includes performance-, safety-, and comfort-related auxiliary drives, of which around 10 % are used as parts of pumping and fan systems. With such “small drives,” i.e., fractional horsepower (FHP) drives at the lower end of the power spectrum, volume, mass, and efficiency have so far only been attributed secondary importance. Yet, the increasing demands on the automotive industry have also resulted in renewed interest not only in the performance parameters of these auxiliary drives, such as energy conversion efficiency, size, and cost, but also in electromagnetic emission, noise, and fault tolerance. This survey article presents selected results on recent achievements in these rather new fields of research and outlines fundamental research questions. Im Zuge der Elektrifizierung der Automobilindustrie wird eine zunehmende Anzahl kleiner elektrischer Antriebe als Hilfsantriebe eingesetzt. Bis zu 100 solcher Antriebe finden sich in einem typischen Mittelklassewagen. Diese erfüllen Funktionen des Fahrverhaltens, der Fahrsicherheit, oder – zunehmend – des Komforts. Rund 10 % dieser Antriebe werden in Pumpen- und Lüftersystemen eingesetzt. Bei solch “kleinen Antrieben”, sogenannten FHP(fractional horsepower)-Antrieben am unteren Ende des Leistungsspektrums, spielten Volumen, Masse und Wirkungsgrad bislang nur eine untergeordnete Rolle. Die steigenden Anforderungen an die Automobilindustrie haben jedoch nicht nur das Interesse an diesen konventionellen Leistungsparametern, sondern auch an anderen Performance Parametern wie elektromagnetische Emissionen, Geräuschentwicklung und Fehlertoleranz, erhöht. Dieser Übersichtsartikel skizziert damit in Zusammenhang stehende grundlegende Forschungsfragen und präsentiert ausgewählte Ergebnisse aus diesen eher neuen Forschungsfeldern. | Performance improvements of auxiliary drives for automotive pump and fan applications | 10.1007/s00502-020-00797-7 |
2020-08-01 | Abstract — The article addresses factors causing damage—in particular, flow accelerated corrosion wear (FAC) of tube walls—to the evaporator operating in the low-pressure loop of the Ep-258/310/35-15.0/3.14/0.44-540/535/263 (P-132) heat-recovery steam generator used as part of a 795-MW combined-cycle plant. Factors influencing the FAC, namely, improper water chemistry, availability of gas shunts in the steam generator, and high mixture motion velocity in the tubes in combination with the flow path configuration, are described. The damages inflicted to the tubes and their locations in the heat-recovery steam generator low-pressure loop are described. It is shown that gas shunts in the heat-recovery steam generator result in an increased heat absorption and higher velocity of medium in the boundary tubes of low-pressure evaporator tube banks, which intensifies the tube’s wear process. It has been found that the water chemistry used for the Kirishi District Power Plant (DPP) heat-recovery steam generator was not the factor that caused damage to the low-pressure loop tubes. The Kirishi DPP steam generator was compared with other similar large-capacity heat-recovery steam generators. For analyzing the low-pressure evaporator performance indicators, the loop and the processes occurring in it were modeled using the Boiler Designer software. An analysis of the results from comparison of the steam generator design and performance characteristics has shown that it is necessary to change the two-phase mixture motion velocity in the Kirishi DPP steam generator low-pressure loop by modifying the design or operating parameters. The wear of the low-pressure evaporator tube walls was mathematically modeled, the results of which confirm that erosion wear is one of the main factors causing damage to the tubes. The erosion is caused by the intense dynamic effect of two-phase, high-velocity flow jets on the tube walls. General recommendations for decreasing the wear of heat-recovery steam generator tubes are given. It has been determined that the increased wear of tubes in the low-pressure loop of the P-132 steam generator at the Kirishi DPP is caused by a combination of a few factors, such as high velocity of steam–water mixture, availability of bends, and unsatisfactory quality of aligning the tubes at their welding places. | Investigation into Factors Causing Damage to Low-Pressure Loop Evaporating Tubes of Large-Capacity Heat-Recovery Steam Generators | 10.1134/S0040601520080030 |
2020-08-01 | Background Low flow anesthesia (LFA) provides a saving up to 75% and improves the dynamics of inhaled anesthesia gas, increases mucociliary clearance, maintains body temperature, and reduces water loss. LFA has been recommended for anesthesiologists in recent years to avoid high fresh gas flow (FGF). However, LFA use is limited due to associated risks. The main purpose of this study was to investigate whether LFA according to body weight, which is the main determinant of oxygen requirement, is feasible and safe in the normoxia range. The second aim was to show that this method can provide economic benefit. Methods Eighty donor hepatectomy cases were included to study in two groups as prospective, observational. A surgery room and a team were allocated only for this study. Considering the oxygen requirement (approximately 3–3.5 mL/kg/min), for the first 40 cases, 10 mL/kg (group 10) FGF was applied; for the second 40 cases, 20 mL/kg (group 20) was applied. Desflurane (Suprane©) was used as an inhalation agent, and analgesia was achieved with remifentanil infusion. Patients’ demographic, respiratory, hemodynamic, and tissue perfusion parameters (SpO 2 and NIRS), and comsumption data (anesthetic agent and CO 2 absorbent) were collected and compared. Results No significant differences were detected between the groups in terms of demographic data, duration of surgery, and hemodynamic, respiratory, and tissue perfusion parameters. These parameters were within normal limits in all patients at all times. The maximum O 2 concentration in the FGF that maintained FiO 2 :0.4 and provided adequate oxygenation during the LFA was 61% (min 56%; max 67%) in group 10, and 47% (min 43%; max 51%) in group 20. The hourly anesthetic agent consumption was significantly different in group 10 than in group 20 (12.4 ± 4 mL vs. 21.5 ± 8 mL/h, respectively ( p < 0.001). Conclusions We performed 10 mL/kg FGF speed without deviating from the safety limits to be FiO 2 :0.4 in donor hepatectomies, reducing the total costs 38% compared with 20 mL/kg FGF. | Feasibility, safety, and economic consequences of using low flow anesthesia according to body weight | 10.1007/s00540-020-02782-y |
2020-08-01 | A study was undertaken to assess the morphological variations during the period 1969–2018 in the twenty-one islands in Gulf of Mannar, southeast India, using Survey of India Toposheet, Google Earth images and field survey techniques. The results show that two of the islands have eroded and submerged, fifteen islands area cover has reduced and four have their area expanded during the last 49 years. Overall, the Tuticorin group of islands has experienced the highest percentage of land cover reduction (78.55%), followed by Keelakarai (43.49%), Vembar (36.21%) and Mandapam (21.84%) groups. The exceptions are the four islands of the Mandapam group viz. Hare, Manoli, Krusadai and Shingle, whose area covers have increased (16.44%). A small change in the area of an island induces a greater change in its morphology. From the Island Change Ratio plot, it is observed that islands with an area cover of 10–30 ha have suffered loss of more area cover and undergone mobility from the core area. The constant changes undergone and the mobility exhibited by these islands clearly indicate that they are dynamic. The main factors that are responsible for the current changes in their extent and position are coral mining and sea level rise. Thus, it is clear that the low-lying reef islands of Gulf of Mannar are very dynamic, and that their expansion, loss in area cover and mobility are mainly controlled by coral mining and climate change. Immediate conservation action is necessary to prevent the islands from submergence. | Eroding islands of Gulf of Mannar, Southeast India: a consequence of long-term impact of coral mining and climate change | 10.1007/s11069-020-03961-6 |
2020-08-01 | Acid anhydrides are used by chemical industries as plasticizers. Trimellitic acid (TMA) is an acid anhydride widely utilized in factories to produce paints, varnishes, and plastics. In addition to causing direct irritant effects, TMA can augment antibody responses in exposed factory workers leading to occupational asthma. Therefore, industries producing TMA have implemented occupational immunosurveillance programs (OISPs) to ensure early diagnosis and medical management, involving exposure reduction/ complete removal of sensitized workers from exposure areas. Multiple animal models (mice strains, rat stains, guinea pig, swine) with different exposure patterns (dermal, nasal, vapor inhalation exposures for different time frames) have been described to elucidate the pathophysiology of TMA exposure. In TMA factories, in spite of implementing advanced environmental controls and personal protective measures to limit exposure, workers become TMA-sensitized. Animal models revealed sIgG, sIgE, sIgA, and sIgM along with pulmonary lesions, cellular infiltrates, alveolar hemorrhage, and pneumonitis associated with TMA exposure. Molecular studies showed involvement of specific functional gene clusters related to cytokine and chemokine responses, lung remodeling, and arginase function. However, thus far, there is no evidence supporting fetotoxic or carcinogenic effects of TMA. OISP data showed IgG and IgE responses in exposed factory workers. Interestingly, timelines for detectable sIgG response, in conjunction with its magnitude, have been shown to be a predictor for future sIgE response. OISPs have been very successful so far at creating a healthy and safe working environment for TMA-exposed factory workers. Graphical Abstract Trimellitic Acid (TMA), used to produce paints, varnishes and plastics, can cause irritant-mediated and immune-mediated occupational health problems. NCBI pubmed search indicated that multiple animal models (different animal types, with chronic vs. acute exposure type, using TMA dust/suspension applied via dermal or other routes) have been used by investigators to elucidate the pathobiology of TMA-exposure. Several outcomes have been measured including humoral, lung/ airway, lymph nodes and dermal/ ear thickening responses. Studies on human subjects have been conducted mostly as parts of Occupational immunosurveillance programs (OISPs) implemented to identify TMA-sensitized workers (using ImmunoCAP and Skin prick testing), monitoring them longitudinally and their medical management including exposure reduction/ complete removal of sensitized workers from exposure areas. Clinical management also includes identification of irritant-induced and/ or immune-mediated outcomes of TMA occupational exposure. Collectively, these studies have led to important insights into the pathomechanism of TMA-exposure and have been very successful at creating a safe working environment for TMA-exposed factory workers. | Health Effects of Trimellitic Anhydride Occupational Exposure: Insights from Animal Models and Immunosurveillance Programs | 10.1007/s12016-020-08801-w |
2020-08-01 | Pyruvate decarboxylase (PDC) is the main enzyme in ethanol fermentation in plant low-oxygen response. Expression of the PDC gene can be induced by submergence, a low-oxygen state, which has been demonstrated in Arabidopsis, maize and rice among other plants. However, it is unknown whether the gene expression has similar pattern in the Fabaceae family under low-oxygen stress, and unavailability of PDC family member sequences in Fabaceae hindered these studies. We aimed to comprehensively identify PDC genes in adzuki bean, and characterize their phylogenetic relationships and expression profile with the emphasis of expression response to submergence. Based on genome sequences and identified conserved domains, HMMER was used to mine PDC genes in adzuki bean in addition to mung bean, both of which are Vigna species under the Fabaceae family. Sequences were aligned using MUSCLE and Phylogenetic topology was decided by using MrBayes. Tissue expression patterns were decided using publically available RNASeq data. Adzuki bean plants were treated with submergence stress, and expressions under treatments were measured using qRT-PCR. We identified the genes in PDC family in the genomes of adzuki bean and mung bean. The known PDC peptides contain three conserved domains with the same order. Based on the domain composition, we identified four PDC family genes in adzuki bean, and three in mung bean. Phylogenetic reconstruction resolved three major classes. Class I of the family was grouped with PDC gene in Arabidopsis, and thus likely encodes PDC; one gene is present in this class in adzuki bean, whose expression was high in roots and nodules compared to other tissues, and was significantly induced under submergence treatment, reaching highest at 12 h after waterlogging. No Class I gene was identified in mung bean, possibly result of assembly gaps or failure of gene model prediction of mung bean genome. Class II genes are clustered together with larger subunit of acetolactate synthase, which have two representatives in mung bean and adzuki bean, respectively. There is one copy of gene in Class III in the genome of the two Vigna species, respectively, which is grouped with an uncharacterized Arabidopsis gene. Interestingly, the adzuki bean gene in this class was significantly induced by waterlogging, whose expression reaching the highest earlier than the Class I gene, which indicates that both the Class I and Class III genes in the PDC family are involved in low-oxygen stress response in adzuki bean. Pyruvate decarboxylase family genes were mined in adzuki bean and mung bean, whose phylogeny was clarified into three independent classes. Expression of a putative PDC gene was significantly elevated by submergence stress in adzuki bean. The Class III gene in adzuki bean was significantly induced in expression by waterlogging, too, yet its expression reached highest earlier than putative PDC genes, suggesting involvement of the Class III genes in low-oxygen stress response. | Submergence response of pyruvate decarboxylase family genes in adzuki bean | 10.2478/s11756-020-00421-1 |
2020-08-01 | Near-surface disposal is anticipated to be the preferred option for the disposal of low and intermediate levels of radioactive waste in Bangladesh. A geographic information system (GIS) and a multi-criteria analysis were used for screening all of Bangladesh to identify potential areas to establish a near-surface disposal facility (NSDF). Five main data criteria, namely geology, hydrology, climatology, pedology and socio-economy, were used in the analysis and were further sub-divided into 14 sub-criteria. Layers of these sub-criteria graded on a scale of 0–5 were used as raw data for the analysis, where 0, 1, 2, 3, 4 and 5 indicate excluded area, completely unsuitable, unsuitable, moderately suitable, suitable and most suitable, respectively. Finally, a suitability map was generated using the analytic hierarchy process and GIS software, which indicated about 1.78% (2621.88 km 2 ) of the total area to be most suitable for the construction of a NSDF in Bangladesh. | Disposal of Low and Intermediate Levels of Radioactive Waste in Bangladesh — An Investigation on the Selection of a Suitable Site by Using a Geographic Information System and a Multi-criteria Analysis | 10.3938/jkps.77.201 |
2020-08-01 | The traditional strength reduction method ( SRM ) uses a single reduction parameter to reduce the cohesion ( c ) and friction coefficient (tan φ ) of a slope. However, this paper develops a new SRM using two different reduction parameters to reduce c and tan φ , by which the critical state of the slope can strictly simultaneously satisfy the upper and lower limit theorem. First, two types of critical state curves ( CSCs ) are established based on the upper and lower limit theorems, respectively, which are used to depict the sufficient conditions for the slope in the critical state. The intersection of two CSC s is considered the most appropriate combination of c/γH and tan φ to lead a slope to the critical state. Second, it is supposed that the most appropriate reduction path is that c and tan φ are reduced towards the intersection of two CSC s. Finally, the differences between the traditional SRM and the proposed method are discussed by analysing five examples with different slope angles. The results show that the potential sliding area of the slope acquired by the proposed method is larger than those obtained from the traditional SRM . The sliding surface of the slope at the critical state acquired by the proposed method can preferably represent the drawing open surface of the back edge. Thus, the traditional SRM may underestimate the sliding range of a slope. | Research on a two-parameter reduction method that strictly satisfies the upper and lower limit theorem | 10.1007/s10064-020-01736-8 |
2020-08-01 | Cell culture-based blood–brain barrier (BBB) models are useful experimental tools for developing central nervous system drugs. Several endothelial cell sources exist for BBB models, including primary cultured brain endothelial cells and immortalized cell lines. Among them, primary cell-based models are considered suitable for the functional analysis of the BBB; however, little is known about the utility of low-passage brain endothelial cells for this purpose. In this study, we investigated the effect of passage on brain endothelial cells from human, mouse and rat brain tissue as BBB models. We established in vitro BBB models using primary brain endothelial cells (Passage 1–Passage 4) from humans, mice, and rats. To analyze the effect of cell type on BBB function, we evaluated transendothelial electrical resistance (TEER) and performed immunofluorescence staining of tight junction proteins. Among the brain endothelial cell models, TEER was highest in the Passage 1 (P1) cell-based BBB model. There was no adequate increase in TEER in other low-passage cultures (P2–P4). A confluent, non-overlapping, uniform monolayer of cells in all P1 cell-based models was visible on immunostaining of tight junction proteins, whereas it was weak or undetectable in more passaged cultures. Increasing passages cultured of brain endothelial cells did not exhibit restrictive BBB function regardless of the cell source and despite culturing with pericytes and astrocytes. Among the tested culture models, only the lowest cultured cell-based models are suitable for functional analysis of the BBB. | Comparison of the rate of dedifferentiation with increasing passages among cell sources for an in vitro model of the blood–brain barrier
| 10.1007/s00702-020-02202-1 |
2020-08-01 | An SARS-CoV‑2 haben sich in den letzten Monaten weltweit Millionen von Menschen infiziert, Hunderttausende sind an den Folgen einer Infektion gestorben. Das Ende der Pandemie ist nicht absehbar und viele Menschen haben Ängste, sich in unterschiedlichen Settings zu infizieren. Der Gasteiner Heilstollen (GHST) ist eine weltweit einmalige ambulante Einrichtung mit den Wirkfaktoren Wärme, hohe Luftfeuchtigkeit und milde Radonstrahlung. In dieser werden jährlich ca. 12.000 Patienten u. a. mit entzündlich-rheumatischen, degenerativen Erkrankungen und chronischen Schmerzen behandelt. Wir haben deshalb die Literatur gesichtet und hinsichtlich einer möglicherweise erhöhten Ansteckungsgefährdung für Patienten während einer Therapie bzw. Kur im GHST analysiert. Aus unserer Sicht sind zum einen die klimatischen und physikalischen Verhältnisse im GHST insgesamt als virenfeindlich anzusehen, zum anderen führen die milde Radonhyperthermie über komplexe physiologische Prozesse sowie die geografische Lage des GHST zu positiven gesundheitlichen Effekten. Daher erscheint uns eine Ansteckungswahrscheinlichkeit für Viren im GHST in keinem Fall erhöht, sondern sogar deutlich geringer als in anderen Settings. The SARS-CoV‑2 has infected millions of humans worldwide in the past few months and hundreds of thousands have died as a result of an infection. The end of the pandemic is not in sight and many people are anxious of becoming infected in different settings. The Gastein Healing Gallery (GHG) is a unique outpatient facility combining heat, high humidity and mild radon radiation. Every year approximately 12,000 patients with inflammatory rheumatic, degenerative diseases and chronic pain are treated. We have therefore reviewed and analyzed the literature with respect to a possible increased risk of infection for patients during treatment in the GHG. On the one hand the climatic and physical conditions in the GHG can be viewed as hostile to viruses and on the other hand the mild radon hyperthermia and the geographic location of the GHG lead to positive effects on the patient’s health via complex physiological processes. We therefore consider the likelihood of infection with viruses in the GHG in no way increased, in contrast, it is probably considerably lower compared to other settings. | Der Gasteiner Heilstollen und eine mögliche Ansteckungsgefahr im Therapiebereich mit Viren | 10.1007/s12688-020-00350-6 |
2020-07-31 | Background Globally, 15 million infants are born preterm each year, and 1 million die due to complications of prematurity. Over 60% of preterm births occur in Sub-Saharan Africa and south Asia. Care at birth for premature infants may be critical for survival and long term outcome. We conducted a prospective audit to assess whether women giving birth preterm could be identified, and to describe cord clamping and neonatal care at hospitals in Africa and south Asia. Methods This prospective audit of livebirths was conducted at six hospitals in Uganda, Kenya, India and Pakistan. Births were considered preterm if between 28 + 0 and 33 + 6 weeks gestation and/or the birthweight was 1.00 to 1.99 kg. A pre-specified audit plan was agreed with each hospital. Livebirths before 28 weeks gestation with birthweight less than 1.0 kg were excluded. Data were collected on estimated and actual gestation and birthweight, cord clamping, and neonatal care. Results Of 4149 women who gave birth during the audit, data were available for 3687 (90%). As 107 were multiple births, 3781 livebirths were included, of which 257 (7%) were preterm. Antenatal assessment correctly identified 148 infants as ‘preterm’ and 3429 as ‘term’, giving a positive predictive value of 72% and negative predictive value of 97%. For term births, cord clamping was usually later at the two Ugandan hospitals, median time to clamping 50 and 76 s, compared with 23 at Kenyatta (Kenya), 7 at CMC (India) and 12 at FBH/LNH (Pakistan). At the latter two, timing was similar between term and preterm births, and between vaginal and Caesarean births. For all the hospitals, the cord was clamped quickly at Caesarean births, with Mbale (Uganda) having the highest median time to clamping (15 s ‘term’, 19 ‘preterm’). For preterm infants temperature on admission to the neonatal unit was below 35.5 °C for 50%, and 59 (23%) died before hospital discharge. Conclusions Antenatal identification of preterm birth was good. Timing of cord clamping varied between hospitals, although at each there was no difference between ‘term’ and ‘preterm’ births. For premature infants hypothermia was common, and mortality before hospital discharge was high. | Identifying women giving birth preterm and care at the time of birth: a prospective audit of births at six hospitals in India, Kenya, Pakistan and Uganda | 10.1186/s12884-020-03126-0 |
2020-07-31 | Background Alpha-fetoprotein (AFP) has been widely used for many years as a serum marker for hepatocellular carcinoma (HCC). However, AFP has been recognized as having poor sensitivity. More and more studies have concluded that circulating microRNAs (miRNAs) might be a promising biomarker that could complement AFP. However, the diagnostic ability of circulating miRNAs has varied among the studies. Therefore, we performed the present meta-analysis to appraise the diagnostic performance of circulating miRNAs as a biomarker for hepatitis B virus-associated HCC (HBV-HCC) patients with low AFP levels. Methods We performed a systematic review and meta-analysis of the published literature to assess the diagnostic accuracy of circulating miRNAs in differentiating HBV-HCC patients with low AFP levels from non-HCC controls. Results Circulating miRNAs showed promising potential in the diagnosis of HBV-HCC patients with low AFP levels. In the low-AFP HBV-HCC patients, the area under the curve (AUC) was 0.88 (95% confidence interval [CI]: 0.84–0.90). The pooled sensitivity and specificity were 0.84 (95% CI: 0.78–0.88) and 0.76 (95% CI: 0.69–0.83), respectively. Conclusions The detection of circulating miRNAs provides a valuable method for the diagnosis of HBV-HCC in patients with low AFP levels. | The role of circulating microRNAs for the diagnosis of hepatitis B virus-associated hepatocellular carcinoma with low alpha-fetoprotein level: a systematic review and meta-analysis | 10.1186/s12876-020-01345-5 |
2020-07-31 | Introduction We treated a patient with late-stage unilateral bypass thrombosis after bilateral axillary-femoral bypass with lateral axillary-profunda femoris artery (LAx-PF) bypass. Case presentation A 64-year-old male patient was admitted to our hospital for acute left lower limb ischemia. Six years ago, he underwent bilateral axillary-femoral bypass due to Leriche syndrome. On emergency admission, thrombosis of the left bypass vessel was identified. Blood flow could not be restored due to failure to restore patency of the proximal and distal anastomosis of the left bypass vessel during surgery. We performed LAx-PF bypass surgery to successfully rescue the limb, which was on the verge of necrosis. Conclusion If thrombectomy cannot restore blood flow in the previous axillary-femoral bypass, LAx-PF bypass is an easy procedure to rescue the ischemic limb. | Case report: lateral axillary-profunda femoris artery bypass for acute lower limb ischemia due to thrombosis after bilateral axillofemoral bypass | 10.1186/s13019-020-01232-w |
2020-07-29 | In recent years, cooling technology for liquid xenon (LXe) detectors has advanced driven by the development of dark matter (DM) detectors with target mass in the 100–1000 kg range. The next generation of DM detectors based on LXe will be in the 50,000 kg (50 t) range requiring more than 1 kW of cooling power. Most of the prior cooling methods become impractical at this level. For cooling a 50 t scale LXe detector, a method is proposed in which liquid nitrogen (LN 2 ) in a small local reservoir cools the xenon gas via a cold finger. The cold finger incorporates a heating unit to provide temperature regulation. The proposed cooling method is simple, reliable, and suitable for the required long-term operation for a rare event search. The device can be easily integrated into present cooling systems, for example the “Cooling Bus” employed for the PandaX I and II experiments. It is still possible to cool indirectly with no part of the cooling or temperature control system getting in direct contact with the clean xenon in the detector. Also, the cooling device can be mounted at a large distance, i.e., the detector is cooled remotely from a distance of 5–10 m. The method was tested in a laboratory setup at Columbia University to carry out different measurements with a small LXe detector and behaved exactly as predicted. | A LN2-based cooling system for a next-generation liquid xenon dark matter detector | 10.1007/s41365-020-00786-7 |
2020-07-29 | Purpose Tuberculosis (TB) is a highly infectious disease caused by Mycobacterium tuberculosis ( Mtb ), which often parasites in macrophages. This study is performed to investigate the bactericidal effect and underlying mechanisms of low-frequency and low-intensity ultrasound (LFLIU) combined with levofloxacin-loaded PLGA nanoparticles (LEV-NPs) on M. smegmatis (a surrogate of Mtb ) in macrophages. Methods and results The LEV-NPs were prepared using a double emulsification method. The average diameter, zeta potential, polydispersity index, morphology, and drug release efficiency in vitro of the LEV-NPs were investigated. M. smegmatis in macrophages was treated using the LEV-NPs combined with 42 kHz ultrasound irradiation at an intensity of 0.13 W/cm 2 for 10 min. The results showed that ultrasound significantly promoted the phagocytosis of nanoparticles by macrophages ( P < 0.05). In addition, further ultrasound combined with the LEV-NPs promoted the production of reactive oxygen species (ROS) in macrophage, and the apoptosis rate of the macrophages was significantly higher than that of the control ( P < 0.05). The transmission electronic microscope showed that the cell wall of M. smegmatis was ruptured, the cell structure was incomplete, and the bacteria received severe damage in the ultrasound combined with the LEV-NPs group. Activity assays showed that ultrasound combined with the LEV-NPs exhibited a tenfold higher antibacterial activity against M. smegmatis residing inside macrophages compared with the free drug. Conclusion These data demonstrated that ultrasound combined with LEV-NPs has great potential as a therapeutic agent for TB. | A synergistic bactericidal effect of low-frequency and low-intensity ultrasound combined with levofloxacin-loaded PLGA nanoparticles on M. smegmatis in macrophages | 10.1186/s12951-020-00658-7 |
2020-07-29 | Climate change currently affects the resilience and aquatic ecosystem. Climate change alters rainfall patterns which have a great impact on river flow. Annual flooding is an important hydrological characteristic of the Mekong River Basin (MRB) and it drives the high productivity of the ecosystem and biodiversity in the Tonle Sap floodplain and the Mekong Delta. This study aims to assess the impacts of climate change on river flow in the MRB and flood inundation in the Lower Mekong Basin (LMB). The changing impacts were assessed by a two-dimensional rainfall-runoff and inundation model (RRI model). The present climate (1979–2003) and future projected climate (2075–2099) datasets from MRI-AGCM3.2H and MRI-AGCM3.2S models were applied with a linear scaling bias correction method before input into the RRI model. The results of climate change suggested that flood magnitude in the LMB will be severer than the present climate by the end of the twenty-first century. The increment of precipitation between 6.6 and 14.2% could lead to increase extreme flow (Q 5 ) 13–30%, peak inundation area 19–43%, and peak inundation volume 24–55% in the LMB for ranging of Representative Concentration Pathways (RCP) and sea surface temperature (SST) scenarios while there is no significant change on peak flood timing. | Assessing the effects of climate change on flood inundation in the lower Mekong Basin using high-resolution AGCM outputs | 10.1186/s40645-020-00353-z |
2020-07-29 | Background Extracellular vesicles (EVs) from human mesenchymal stem cells (hMSCs) are known to be mediators of intercellular communication and have been suggested as possible therapeutic agents in many diseases. Their potential use in intervertebral disc (IVD) degeneration associated with low back pain (LBP) is yet to be explored. Since LBP affects more than 85% of the western population resulting in high socioeconomic consequences, there is a demand for exploring new and possibly mini-invasive treatment alternatives. In this study, the effect of hMSC-derived small EVs (sEVs) on degenerated disc cells (DCs) isolated from patients with degenerative discs and chronic LBP was investigated in a 3D in vitro model. Methods hMSCs were isolated from bone marrow aspirate, and EVs were isolated from conditioned media of the hMSCs by differential centrifugation and filtration. 3D pellet cultures of DCs were stimulated with the sEVs at 5 × 10 10 vesicles/ml concentration for 28 days and compared to control. The pellets were harvested at days 7, 14, and 28 and evaluated for cell proliferation, viability, ECM production, apoptotic activity, chondrogenesis, and cytokine secretions. Results The findings demonstrated that treatment with sEVs from hMSCs resulted in more than 50% increase in cell proliferation and decrease in cellular apoptosis in degenerated DCs from this patient group. ECM production was also observed as early as in day 7 and was more than three times higher in the sEV-treated DC pellets compared to control cultures. Further, sEV treatment suppressed secretion of MMP-1 in the DCs. Conclusion hMSC-derived sEVs improved cell viability and expedited chondrogenesis in DCs from degenerated IVDs. These findings open up for new tissue regeneration treatment strategies to be developed for degenerative disorders of the spine. | Extracellular vesicles from human mesenchymal stem cells expedite chondrogenesis in 3D human degenerative disc cell cultures | 10.1186/s13287-020-01832-2 |
2020-07-27 | Low-speed friction riveting, a novel method of joining hybrid structures, is a promising technology for joining polymer with metallic structures in automotive and aerospace industries. It offers unique advantages such as weight reduction, reduced consumption of fuel and its cost without compromising the required mechanical properties. The present work deals with riveting of polymethyl methacrylate (PMMA) to aluminium (AA 1100) rivets using low-speed friction riveting technique. It reports the possibility of friction riveting at lower speed and its influence on the integrity of the hybrid joints. The performance evaluation of the low-speed-friction-riveted components is done by carrying out a series of mechanical tests. Microstructural investigation reveals the formation of distinct zones on the riveted components and modes of failure identified during the tensile and bending tests. Besides, numerical simulation of the low-speed friction riveting process has been carried out using ABAQUS 6.14-1 for better understanding of the process. The developed numerical model could be used as a tool to predict the temperature distribution. Validation shows that there is a good agreement between experimental and numerical results. | Low-speed friction riveting: a new method for joining polymer/metal hybrid structures for aerospace applications | 10.1007/s40430-020-02519-8 |
2020-07-22 | In this study, newly designed perylene diimide based polymers P1 and P2 were synthesized and were used as hole transporting materials in place of the more common spiro-OMeTAD in perovskite solar cells. The co-polymers P1 - P2 were synthesized by Suzuki and direct arylation polymerizations of 2,9-bis(7-bromo-9,9-dioctyl-9 H -fluoren-2-yl)anthra[2,1,9-def:6,5,10- d ’ e ’ f ’]diisoquinoline-1,3,8,10(2 H ,9 H )-tetrone M1 with 5,11-bis(2-hexyldecyl)-3,9-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,11-dihydoindolo[3,2-b]carbazole M2 and 3-octylthiophene M3 , respectively. P1 and P2 exhibit broad absorption spectra in thin film and solution with the absorption extending from the ultraviolet to visible and near infrared region of the solar spectrum. The water contact angles of P1 - P2 were determined to be 100.8° and 122.9°, respectively, showing good hydrophobicity for the synthesized copolymers. Both polymers show steady state photoluminescence quenching when blended with perovskite. Perovskite solar cell devices fabricated using P1-P2 in place of spiro-OMeTAD show power conversion efficiencies of 13.02% and 10.74%, respectively and manifest the potential of this class of materials as promising alternatives to conventionally used spiro-OMeTAD. Graphical Abstarct Table of Contents (TOC) Graphic . | Perylene diimide based low band gap copolymers: synthesis, characterization and their applications in perovskite solar cells | 10.1007/s10965-020-02212-3 |
2020-07-21 | Silicon Physical Unclonable Function (PUF) is a general hardware security primitive for security vulnerabilities. Recently, Quasi-adiabatic logic based physical unclonable function (QUALPUF) has ultra low-power dissipation; hence it is suitable to implement in low-power portable electronic devices such radio frequency identification (RFID) and wireless sensor networks (WSN), etc. In this paper, we present a design of 4-bit QUALPUF which is based on static random access memory (SRAM) for low-power portable electronic devices and then shows the post-layout simulation and measurement results. To evaluate the uniqueness and reliability, the 4-bit QUALPUF is implemented in 0.18 $$\upmu$$ μ m standard CMOS process with 1.8 V supply voltage. The 4-bit QUALPUF occupies 58.7 $$\times$$ × 15.7 $$\upmu \mathrm {m}^{2}$$ μ m 2 of layout area. The post-layout simulation results illustrate that the uniqueness calculated from the inter-die HDs of the 4-bit QUALPUF is 47.58%, the average reliability is 95.10%, and the the energy dissipation is 29.73 fJ/cycle/bit. The functional measurement results of the fabricated chip are the same as the post-layout simulation results. | Quasi-Adiabatic SRAM Based Silicon Physical Unclonable Function | 10.1007/s42979-020-00253-5 |
2020-07-20 | Microalgae Nannochloropsis sp. is a widely recognized renewable biodiesel feedstock. The ability of this microalgae to absorb CO 2 constitutes an added value toward reducing global warming. However, the process of optimizing its growth still involves many challenges. Photoinhibition, which takes places during microalgae cultivation when using continuous lighting, constitutes an unresolved problem. Therefore, the optimum light/dark cycle method is considered necessary. The experiments were conducted using a designed, tubular airlift photobioreactor and blue, energy-saving, light-emitting diode (LED) lights for the purpose of internal illumination. We observed that a 45:15 min (light:dark) cycle increased the production of Nannochloropsis sp. biomass significantly, with a cell density, wet weight, and lipid content of 17 × 10 6 cell/ml, 7.11 g, and 10.1% dry weight, respectively. By using the blue LED lights, our designed, airlift photobioreactor increased cell growth by 70% compared to the growth of Nannochloropsis sp. in nature and produced 61 times higher lipid content compared to Nannochloropsis sp. that is exposed to natural light. | Enhanced biomass productivity of microalgae Nannochloropsis sp. in an airlift photobioreactor using low-frequency flashing light with blue LED | 10.1186/s40643-020-00331-9 |
2020-07-20 | Background The objective of this randomized clinical trial was to evaluate Low-Level Laser Therapy (LLLT) effectiveness in spontaneous and chewing pain reduction following initial orthodontic archwire placement. Methods 26 patients (mean age 20.07 ± 3.13 years) with maxillary Little’s Irregularity Index (LII) of 7 mm or more that indicates first maxillary premolars extraction and no medications intake were eligible for this trial. Patients were randomly assigned with 1:1 ratio using simple randomization technique to receive either LLL or placebo treatment. Blinding was applicable for patients only. In the laser group, patients received a single LLL dose (wavelength 830 nm, energy 2 J/point) in four points (2 buccal, 2 palatal) for each maxillary anterior tooth root. Patients in the placebo group had the same laser application procedure without emitting the laser beam. Patients were asked to score spontaneous and chewing pain intensity by filling out a questionnaire with a 100-mm Visual Analogue Scale (VAS) after 1, 6, 24, 48, and 72 h of treatment application. Independent t-test was used to compare the mean pain scores between the laser and placebo groups for both spontaneous and chewing pain at each studied time point. Results No dropout occurred so the results of the 26 patients were statistically analyzed. Despite some clinical differences observed between the two groups, no statistical significance was found for each studied time point ( p > 0.05) for both spontaneous and chewing pain except after 72 h for chewing pain with a VAS score of (18.84 ± 13.44) mm for the laser group compared to (38.15 ± 27.06) mm for the placebo group. Conclusions LLLT, with the suggested parameters, is not effective in pain reduction following initial orthodontic archwire placement. Trial registration Name of the registry: Clinicaltrials.gov Trial registration number: NCT02568436. Date of registration: 26 September 2015 ‘Retrospectively registered’. | Low-level laser therapy effectiveness in reducing initial orthodontic archwire placement pain in premolars extraction cases: a single-blind, placebo-controlled, randomized clinical trial | 10.1186/s12903-020-01191-7 |
2020-07-19 | In Argentina, the yield potential of rice ( Oryza sativa L.) under suboptimal temperatures of temperate regions and during early sowing in tropical regions depends on its low-temperature germinability (LTG) and subsequent cold tolerance at the seedling stage (CTS). This study focused on the phenotyping and identification of contrasting henotypes for LTG and CTS of 18 rice genotypes genotyped with 49 markers previously linked to cold tolerance. The selected markers revealed phenotypic variability among the genotypes evaluated. The results also demonstrated that both traits are regulated by different genes and that CTS is associated with differential alleles of candidate gene (CG)-based markers. Biplot clustering analysis allowed the selection of two cultivars, H298a/90 and Puitá INTA CL, contrasting for LTG, CTS and CG alleles. An F 2 population (n = 128) derived from these two cultivars was genotyped with 43 SSR- and CG-based markers and 89 F 2:3 families (~ 1800 seedlings) phenotyped for CTS. Single-marker analysis detected two major QTL that had been previously reported for CTS: qCTS11 , which explained 18.35% of the phenotypic variance at 7 days of treatment, and qCTS12 , which explained 26.62% and 47.94% of the phenotypic variance at 7 and 14 days of treatment, respectively. Marker-assisted introgression of QTL alleles favorable for CTS into Puitá INTA CL, which has high LTG, could contribute to obtaining breeding lines with early seedling vigor adapted to the sowing season in Argentina. | Phenotyping and QTL mapping for cold tolerance at the germination and seedling stages in Argentine temperate rice | 10.1007/s10681-020-02661-3 |
2020-07-17 | Background Plants are always exposed to dynamic light. The photosynthetic light use efficiency of leaves is lower in dynamic light than in uniform irradiance. Research on the influence of environmental factors on dynamic photosynthesis is very limited. Nitrogen is critical for plants, especially for photosynthesis. Low nitrogen (LN) decreases ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and thus limits photosynthesis. The decrease in Rubisco also delays photosynthetic induction in LN leaves; therefore, we hypothesized that the difference of photosynthetic CO 2 fixation between uniform and dynamic light will be greater in LN leaves compared to leaves with sufficient nitrogen supply. Results To test this hypothesis, soybean plants were grown under low or high nitrogen (HN), and the photosynthetic gas exchange, enzyme activity and protein amount in leaves were measured under uniform and dynamic light. Unexpectedly, dynamic light caused less photosynthetic suppression, rather than more, in LN leaves than in HN leaves. The underlying mechanism was also clarified. Short low-light (LL) intervals did not affect Rubisco activity but clearly deactivated fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-1,7-bisphosphatase (SBPase), indicating that photosynthetic induction after a LL interval depends on the reactivation of FBPase and SBPase rather than Rubisco. In LN leaves, the amount of Rubisco decreased more than FBPase and SBPase, so FBPase and SBPase were present in relative excess. A lower fraction of FBPase and SBPase needs to be activated in LN leaves for photosynthesis recovery during the high-light phase of dynamic light. Therefore, photosynthetic recovery is faster in LN leaves than in HN leaves, which relieves the photosynthetic suppression caused by dynamic light in LN leaves. Conclusions Contrary to our expectations, dynamic light caused less photosynthetic suppression, rather than more, in LN leaves than in HN leaves of soybean. This is the first report of a stress condition alleviating the photosynthetic suppression caused by dynamic light. | Dynamic light caused less photosynthetic suppression, rather than more, under nitrogen deficit conditions than under sufficient nitrogen supply conditions in soybean | 10.1186/s12870-020-02516-y |
2020-07-16 | In this work, the idea of parallel computing for a full adder has been proposed. Based on parallel computing, a new architecture of full adder (A-I) has been proposed in which the input needs to pass through only two transistors to reach the output node which results in reduced delay time. The second design of full adder (A-II) has been proposed with two-phase clocked adiabatic static complementary metal oxide logic which results in decreased power dissipation. The third design of full adder (A-III) uses parallel computing for both sum and carry generation. In A-III, a buffer has been introduced to restore the logic level which proves the drive capability of parallel computing logic. The adiabatic logic-based proposed design A-II shows a 61.95% improved power delay product (PDP) as compared to the best-reported body biasing approach-based adder, whereas the fully parallel computing-based design A-III shows a 53.29% improved PDP as compared to double pass transistor-based full adder. Post layout results of the proposed design A-III verified the functionality of proposed parallel computing logic. The proposed designs also perform well under varied temperature conditions. These designs show satisfactory performance at low voltages, whereas the use of adiabatic logic makes these designs energy efficient for low power applications. | Implementation of parallel computing and adiabatic logic in full adder design for ultra-low-power applications | 10.1007/s42452-020-3188-z |
2020-07-14 | Background Maize ( Zea mays L.) is one of the main agricultural crops with the largest yield and acreage in the world. However, maize germplasm is very sensitive to low temperatures, mainly during germination, and low temperatures significantly affect plant growth and crop yield. Therefore, the identification of genes capable of increasing tolerance to low temperature has become necessary. Results In this study, fourteen phenotypic traits related to seed germination were used to assess the genetic diversity of maize through genome-wide association study (GWAS). A total of 30 single-nucleotide polymorphisms (SNPs) linked to low-temperature tolerance were detected (−log10( P ) > 4), fourteen candidate genes were found to be directly related to the SNPs, further additional 68 genes were identified when the screen was extended to include a linkage disequilibrium (LD) decay distance of r 2 ≥ 0.2 from the SNPs. RNA-sequencing (RNA-seq) analysis was then used to confirm the linkage between the candidate gene and low-temperature tolerance. A total of ten differentially expressed genes (DEGs) (|log 2 fold change (FC)| ≥ 0.585, P < 0.05) were found within the set distance of LD decay ( r 2 ≥ 0.2). Among these genes, the expression of six DEGs was verified using qRT-PCR. Zm00001d039219 and Zm00001d034319 were putatively involved in ‘mitogen activated protein kinase (MAPK) signal transduction’ and ‘fatty acid metabolic process’, respectively, based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Thus, these genes appeared to be related to low-temperature signal transduction and cell membrane fluidity. Conclusion Overall, by integrating the results of our GWAS and DEG analysis of low-temperature tolerance during germination in maize, we were able to identify a total of 30 SNPs and 82 related candidate genes, including 10 DEGs, two of which were involved in the response to tolerance to low temperature. Functional analysis will provide valuable information for understanding the genetic mechanism of low-temperature tolerance during germination in maize. | Identification of candidate tolerance genes to low-temperature during maize germination by GWAS and RNA-seq approaches | 10.1186/s12870-020-02543-9 |
2020-07-14 | Drilling and blasting play an important role in operation cycle of a mine or quarry. Optimum blast design plays a pivotal role to achieve maximum utilization of explosive energy and blast fragmentation. Only 20 to 30% of explosive energy is utilized for fracturing and fragmentation of rock, and the rest of the energy is converted in noise, air overpressure, ground vibration, etc. It has been observed that using the low-density explosive may reduce the deleterious effect of engineering blasting with desired blast fragmentation. This paper substantiates this fact wherein distinct explosive energy utilization enhancement has been achieved with the use of low-density explosive and reduces ground vibration. This paper outlines the on-field assessment of low-density explosive in Quarry AB of Tata Steel West Bokaro Division. It is a solid sensitized emulsion blend. It comprises products designed for blasting in dry, dewatered, and wet blast-hole applications. Low-density explosive provides the capability to better match explosive performance to ground conditions. Being a low-density, low-energy explosives, it provides an added benefit of reducing the environmental effects of blasting. The key objective of the field assessment was to test the on-field performance of the new low-density bulk products and its effects on blast-induced ground vibration and air overpressure. | Reduction of blast-induced ground vibration and utilization of explosive energy using low-density explosives for environmentally sensitive areas | 10.1007/s12517-020-05645-8 |
2020-07-13 | We have developed the low-temperature conformal ZnO nanowire fabrication on flexible plastic substrates by utilizing the solution-processible metal seed-assisted hydrothermal ZnO crystallization. Structural evolution of ZnO nanowires controlled by major parameters involving growth temperature, growth time, and seed coating condition, has been systematically investigated towards uniform and large-area growth of conformal ZnO nanowires. Direct ZnO nanowire growth on flexible plastics without undergoing the high-temperature seed sintering has been realized by developing the low-temperature Ag-seeded hydrothermal ZnO nanowire growth. The nanoporous Ag layer favorable for ZnO crystal nucleation and continued nanowire growth can be reduced from the Ag ion solution coating at the temperature as low as 130 °C. This tactfully enables the selective hydrothermal growth of ZnO nanowires on the Ag patterns on flexible plastics. Such an all-solution-processible low-temperature fabrication protocol may provide an essential and practical solution to develop many diverse applications including wearable and transparent electronics, sensors, and photocatalytic devices. As one example, we demonstrate that a transparent UV sensor can be devised based on the ZNW growth on the Ag micromesh electrode. | Low-temperature large-area fabrication of ZnO nanowires on flexible plastic substrates by solution-processible metal-seeded hydrothermal growth | 10.1186/s40580-020-00235-6 |
2020-07-13 | The hypothesis that the incorporation of halloysite nanotubes (HNTs) into low-density polyethylene (LDPE)/thermoplastic starch (TPS) blends could lead to materials with mechanical and flow properties close to those of pure LDPE but with improved potential biodegradability, was investigated. A 50 wt.%/50 wt.% LDPE/TPS blend was prepared via extrusion and injection molding, by using different HNT contents up to 8 wt.%. The obtained nanocomposite structure and properties was investigated. The SEM images and EDS analyses indicated that the HNTs were preferentially located within the starch-rich phases of the blend. Moreover, the addition of 8 wt.% HNTs to the LDPE/TPS blend promoted a pronounced enhancement in mechanical properties with respect to those of the original blend, leading to properties resembling those of pure LDPE. The results suggest that nanocomposites can be interesting candidates for the replacement of LDPE in applications in which the biodegradability of the proposed blend can reduce the environmental impact of traditional LDPE short-life products. | Effect of incorporation of Halloysite nanotubes on the structure and properties of low-density polyethylene/thermoplastic starch blend | 10.1007/s10965-020-02185-3 |
2020-07-09 | Pressmud is one of the most abundant wastes produced in the sugarcane industry; however, far too little attention has been paid to it as a reactive material for pollutant removal. This paper investigates the potential use of the composted pressmud for Cd 2+ removal and considers the possible remobilization of the ion after the use and subsequent disposal of this material. Characterization and adsorption analyses (batch equilibrium and kinetic) were carried out in addition to desorption and bioaccessibility assays. The pressmud revealed promising adsorption characteristics, including a high specific surface area (SSA) (236.1 m 2 g −1 ) and the presence of oxygen surface functional groups. The batch equilibrium data exhibit a better fit with the Langmuir isotherm model, assuming a monolayer adsorption capacity of 12.063 mg g −1 , and for kinetic data, the pseudosecond-order model satisfactorily suited the adsorption. The equilibrium time was attained rapidly at lower concentrations (within 30 min), increasing to 180 min at 500 mg L −1 , due to the contribution of the intraparticle diffusion process. According to the desorption and bioaccessibility tests, pressmud is capable of maintaining the element at the binding sites, although the Cd 2+ adsorbed by the material is almost in its bioaccessible form, which supports the need of the correct handling after use. The results indicate that pressmud may be a promising reactive material for Cd 2+ adsorption, identifying upcycling opportunities for this low-cost and renewable waste. | The Potential Use of Pressmud as Reactive Material for Cd2+ Removal: Adsorption Equilibrium, Kinetics, Desorption, and Bioaccessibility | 10.1007/s11270-020-04746-0 |
2020-07-09 | Background Reduced protein diet manifested potential to mitigate heat production based on the concept of ideal amino acid profile. The hypothesis of this study was that lactating sows fed a low crude protein (LCP) diet with supplemental amino acid produce less heat compared to those fed a high crude protein (HCP) diet under both thermal neutral (TN) and heat stress (HS) conditions. Methods Thirty-two lactating sows were allotted to HCP (193 g CP/kg) and LCP (140 g CP/kg) diets under thermal neutral (TN, 21 ± 1.5 °C) or cycling heat stress (HS, 32 ± 1.5 °C daytime and 24 ± 1.5 °C nighttime) conditions. Diets contained 0.90% SID lysine and 10.8 MJ/kg net energy. Positive pressure indirect calorimeters were used to measure gas exchange in individual sows with litters, and individual piglets on days 4, 8, 14 and 18. Sow and litter weights were recorded on days 1, 10 and 21. Results Sow total heat production (THP) was calculated by subtracting litter THP from sow + litter THP based on BW 0.75 . Sow BW and body protein (BP) loss was greater for LCP diet compared to HCP diet in peak lactation ( P < 0.05 and P < 0.01, respectively) and throughout the entire lactation period ( P < 0.05 and P = 0.056, respectively) under HS conditions. Heat-stressed sows fed HCP diet had higher ( P < 0.05) rectal temperature at 13:00 ( P < 0.05) and 19:00 ( P < 0.01), and higher respiration rate at 07:00 ( P < 0.05), 13:00 ( P < 0.05) and 19:00 ( P < 0.05) compared to TN sows fed HCP diet. In sows fed LCP diet, those under HS tended to have higher ( P = 0.098) rectal temperature at 13:00 and had higher ( P < 0.05) respiration rate at 07:00, 13:00 and 19:00 compared to TN sows. The relationship between daily THP and days in lactation of sows fed LCP diet was quadratic ( P < 0.05), with an ascending trend until day 14 and a descending trend from days 14 to 18. Sows fed LCP diet had lower daily THP at day 18 ( P < 0.001) compared to those fed the HCP diet under HS conditions. Conclusion Reduction in THP in sows fed LCP diet was largely associated with THP on day 18 of lactation under HS conditions. Feeding LCP diets alleviated the increased body temperature in sows under HS conditions throughout lactation, which was accompanied by a reduction in respiration rate. Total heat production is associated with days in lactation, in particular under HS conditions with THP appearing to peak between days 14 and 18. | Effect of dietary near ideal amino acid profile on heat production of lactating sows exposed to thermal neutral and heat stress conditions | 10.1186/s40104-020-00483-w |
2020-07-09 | Low-cost air quality sensors are widely used to improve temporal and spatial resolution of air quality data. In Lima, Peru, only a limited number of reference air quality monitors have been installed, which has led to a lack of data for establishing environmental and health policies. Low-cost technology is promising for developing countries because it is small and inexpensive to operate and maintain. However, considerable work remains to be done to improve data quality. In this study, a low-cost sensor was installed with a reference monitor station as the first stage for the calibration process, and a multiple regression model was developed based on reference measurements as an outcome variable using sensor data, temperature, and relative humidity as the predictive parameters. The results show that this particular technology exhibits a promising performance in measuring PM 2.5 and PM 10 (particulate matter with diameter aerodynamic less than 2.5 μm and 10 μm, respectively); however, the correlation for PM 2.5 appears to be better. Temperature and relative humidity data from the sensor were only partially analyzed due to the evident low correlation with the reference meteorological data. The objective of this study is to begin analyzing the performance of low-cost sensors that have already been introduced to the Peruvian market and selecting those that perform better to provide for informed decision-making. | Development of a multiple regression model to calibrate a low-cost sensor considering reference measurements and meteorological parameters | 10.1007/s10661-020-08440-w |
2020-07-06 | The well-known archaeological site of Anahita Temple at Kangavar is one of the most important Iranian stone monuments. It has been dated by various authors in an interval extended from Achaemenid to Sasanian Persian Empires (sixth century BCE to seventh century AD). Significant weathering has been occurred in various stone blocks used in the construction of this monument. The aim of this research is to study the deterioration process of the stone blocks used in the Temple. It includes chemical and mineralogical analysis of stones, characterization of deterioration patterns and processes, and identification of factors influenced the process. Results have been obtained by on-site and laboratory studies, including optical microscopy, petrography, X-ray fluorescence, X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy methods. They showed that low-porosity limestone and dolomitic limestone have been used in the construction of the Temple, which have a compact micritic structure with variable size calcite veins (sparite) and clay veins. According to the on-site and laboratory studies, the deterioration patterns are partially similar in majority of the stone blocks and include different types of detachments as well as biological colonisations. The multianalytical results proved that the deterioration process is mainly of physical weathering type, due to structural and chemical characteristics of the limestone as well as climate factors, temperature fluctuations in particular. It turned out that limestone characteristics (including presence of clay veins as well as heterogeneity of calcitic matrix (micrite and sparite)) can affect the behaviour of stone blocks against climate factors; helping us to find reasons behind physical weathering of limestone in the cultural/historical sites and monuments. | The deterioration process of limestone in the Anahita Temple of Kangavar (West Iran) | 10.1186/s40494-020-00411-1 |
2020-07-06 | The major conduit of water and sediment discharges from the mighty Ganges-Brahmaputra-Meghna river system to the Bay of Bengal, the Lower Meghna River (LMR), experiences rapid morphological changes with significant environmental and socioeconomic consequences to the surrounding areas. This study measures the rate of bankline shifting, river widening, and change in the braiding index (BI) in the LMR over a period of 30 years (1988–2017) in order to understand the channel dynamics. To extract these parameters, we used the Digital Shoreline Analysis System (DSAS) together with other geospatial techniques on multiple satellite images taken over this period and subsequently validated the spatial outcomes through an extensive field investigation. Our findings revealed that rapid changes occurred in both banks, although at different rates, mostly due to erosion; the right bank has retreated at an average rate of 81 m/yr and the left bank at 28 m/yr, resulting in widening as well as river migration to the west. The channel widening, an overall average increase of about 49%, has been accompanied by a substantial increase in the BI, from 2.2 in 1988 to 6.4 in 2017. This study suggests that the higher erosion rate in the right bank and the consequent westward migration of the river are due to the active tectonic setting of the adjoining areas. Enormous volumes of water and sediment discharges and their periodic variations, heterogeneous bank material properties, climate change, and anthropogenic activities are also possible contributors to this bank instability. This research shows the value of implementing an integrated GIS-DSAS tool for spatiotemporal channel change investigation and could be useful in land-use planning and mitigating bank erosion in the LMR locality. | Assessing bank dynamics of the Lower Meghna River in Bangladesh: an integrated GIS-DSAS approach | 10.1007/s12517-020-05514-4 |
2020-07-02 | The Lower Ordovician succession, consisting of the Yingshan and Penglaiba formations, encompasses significant petroleum reservoirs in Yubei area, southwest Tarim Basin. Mesogenetic dissolution and dolomitization strongly contributed to the increase in rock porosities here. Wells YB 7, YB 5, and YB 1-2X drilled in eastern Yubei area met the deposits of Yingshan and Penglaiba formations, providing abundant data for the mesogenetic diagenesis analysis. Among them, Well YB 5 encountered the thickest Penglaiba Formation and was chosen for detailed analysis. Eight diagenetic elements (i.e., micrite encrust, radial fibrous calcite cement, stylolites, poikilotopic calcite cement, dolomite, fracture, bladed quartz, and equant quartz) are identified and ascribed to seven paragenetic events. Their Paragenetic sequence evidences Yingshan and Penglaiba Formations experienced severe deep burial diagenesis. The presence of green luminescent fluorite, non-luminescent and zoned quartz, and violet to orange luminescent saddle dolomite with sweeping extinctions, together with the positive Eu 2+ anomalies shown in the rare earth element (REE) patterns all help to ascribe the buried dissolution and dolomitization to the incorporation of hydrothermal fluids. The inconsistency between the REE patterns of the Yingshan and Penglaiba formations and that of the organic-rich source rocks of Lianglitage and Bachu Formations exclude the assumption that hydrocarbon influx caused the mesogenetic dissolution. High-angle fractures, generated by the Middle Caledonian–Early Hercynian tectonic movements, acted as conduits for hydrothermal fluid migration and promoted the mesogenetic dissolution to form dolomite reservoirs. The coincidence that samples with positive Eu 2+ anomalies all fall in the basalt province, while samples lacking positive Eu 2+ anomalies from Tahe fall out, backs up that the main source of the hydrothermal fluid promoting the mesogenetic dissolution was probably derived from the Permian magma. Strata possessing similar geochemical and petrological characteristics as Yingshan and Penglaiba formations in eastern Yubei area, and experiencing subsequent tectonic and magmatic activities could be potential exploration targets in further exploration practice in Tarim Basin and in the other basins in the world. | Mesogenetic diagenesis of the Ordovician limestone in Yubei area, Tarim Basin, NW China | 10.1007/s13146-020-00610-8 |
2020-07-01 | Results of preparing Portland cement by low-energy technology using technogenic raw materials are presented. Coal mining waste and tephritobasalt in a ratio of 1:1 are used as the clay component, and granulated lead slags are used instead of scarce pyrite cinder. Correlation of the influence of charge compositions, saturation coefficient, silicate and alumina moduli, firing regimes with chemical and mineral composition and clinker and cement quality are established. Composition of the raw material mixtures is calculated according to a ROCS program, and the free CaO content in clinker composition is determined. Experimental cement strength is tested after hardening for 7 and 28 days. Its physicomechanical characteristics and structure are studied. | Preparation Low-Energy Content Cement from Technogenic Raw Materials | 10.1007/s11148-020-00449-5 |
2020-07-01 | Abstract A UV-crosslinkable two-component organically modified silicate (ORMOSIL) sol–gel coating was made using 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) in two stages. In the first stage, key synthetic parameters, such as use of co-solvents, reaction temperature, reaction time, and catalyst, were optimized for the rapid hydrolysis and condensation of the ORMOSIL. The ORMOSIL material was made using isopropanol as the solvent and HNO 3 as the acid catalyst. This resulted in a sol–gel that underwent rapid hydrolysis in 35 s. The ORMOSIL demonstrated extensive condensation after 10 min of stirring at room temperature followed by 10 min of heating at 60°C as monitored by 29 Si-NMR. In the second stage, the ORMOSIL was successfully crosslinked with up to 70% consumption of the acryl functionality within 5 min under UV light exposure in the presence of photoinitiator. The UV-crosslinked coating exhibited high adhesion to low-carbon steel and impeded substrate corrosion from 17 to 25 h under an accelerated corrosive environment. Graphic abstract Schematic representation of the hydrolysis and condensation of 3-methacryloxypropyltrimethoxysilane (MaPTMS) and tetraethoxysilane (TEOS) system and the 2D gHMBC 29 Si NMR of the system. | Curable hybrid materials for corrosion protection of steel: development and application of UV-cured 3-methacryloxypropyltrimethoxysilane-derived coating | 10.1007/s11998-019-00317-z |
2020-07-01 | The paper presents the results of numerical simulation for the process of production of hollow microspheres during heating and melting of porous particles of silica (the precursor) by a flow of low-temperature plasma. This model takes into account the partial capturing of gas in the particle and offers the laws of evolution for the hollow microsphere diameter and the wall thickness for different precursors with the size D 0 = (50–150) microns and porosity P p = (0.2–0.6). | Simulation of production of hollow silica particles in a plasma flow. Part 2. Hollow particle production dynamics | 10.1134/S0869864320040125 |
2020-07-01 | Abstract A study of the thermal effects observed during the low-temperature pyrolysis of various types of pelletized biomass (sunflower husk, coniferous wood, litter-litter mass) is presented. It is shown that during sunflower husk torrefaction the greatest exothermic effect is observed and the possible reasons for its occurrence are explained. The influence of a small oxygen content in the heating medium on the exothermic effects during biomass torrefaction is analyzed. It has been suggested that the use of internal energy resources of the process (waste heat of exhaust gases and internal energy released in the process of biomass torrefaction) significantly increases the torrefaction process energy efficiency and allows to consider secondary biomass as a real competitor to traditional fuels, a substitute for fossil coal. | Thermal Effects during Biomass Torrefaction | 10.3103/S0361521920040084 |
2020-07-01 | With the purpose of further investigating the influence of aging on the tensile behaviors of hydroxyl-terminated polybutadiene (HTPB) propellant at low temperatures under dynamic loading, uniaxial tensile stress responses of thermal accelerated aged propellant samples at different temperatures (223–298 K) and strain rates ( 0.40 – 42.86 s − 1 $0.40\mbox{--}42.86~\mbox{s}^{-1}$ ) were obtained through the use of a new INSTRON testing machine. And scanning electron microscope (SEM) was employed to analyze the microscopic damage of HTPB propellant under the test conditions. Test results indicate that aging can significantly affect the characteristics of the stress-strain curves, mechanical properties and fracture mechanisms of HTPB propellant at low temperatures under dynamic loading. There are three regions in the tensile stress-strain curves of aged propellant when deforming at lower temperatures and the highest strain rate, however, there are five ones for unaged propellant. At lower temperatures and higher strain rates, the strain at maximum tensile stress of the propellant decreases more obviously after aging. Moreover, the variation of mechanical parameters for HTPB propellant with aging time are highly complex due to the occurrence of oxidative cross-linking during aging and the distinct changes of the fracture mechanisms. These variation were reasonably well described with linear model and the improved exponential model in this investigation. The fracture mechanism of aged propellant can change from dewetting, matrix tearing and AP particle fracture to only AP particle fracture with increasing strain rate for the entire test temperature range, and the strain rate for this transition is all at 4.00 – 14.29 s − 1 $4.00\mbox{--}14.29~\mbox{s}^{-1}$ . In addition, the microscopic damage of HTPB propellant becomes more severe with the thermal aging time rising, however, this effect is weaker at higher strain rates after long-time thermal aging. Finally, the master curves of typical mechanical parameters for aged HTPB propellant were constructed according to the time-temperature superposition principle (TTSP). | Tensile behaviors of thermal aged HTPB propellant at low temperatures under dynamic loading | 10.1007/s11043-019-09413-4 |
2020-07-01 | A new low-power Si 1− x Ge x pocket junctionless single-gate tunnel field-effect transistor (JLSGTFET) is designed to achieve steep subthreshold performance and a better I ON / I OFF ratio (∼ 10 8 ) in sub-20-nanometer technology node. The mole fraction of Ge represented by x is kept at 0.3 for the SiGe pocket region. The proposed JLSGTFET shows better performance with a Ge mole fraction value x = 0.3. The mole fraction value affects various electrical parameters in terms of leakage current, junction capacitance and transconductance of the channel region. The device exhibits reduced switching capacitance due to the smaller-bandgap pocket region between the source and channel. Analysis of the JLSGTFET is carried out for DC and AC parameters at room temperature. Temperature analysis plays a vital role in determining reliable ON- and OFF-state performance in transistors. Therefore, the proposed pocket JLSGTFET is investigated under harsh temperature conditions to characterize the performance for DC and subthreshold parameters. The sensitivity of the device is analyzed under different temperature conditions over a range of 250–400 K to observe subthreshold performance including transfer characteristics, output characteristics, I ON / I OFF ratio, subthreshold slope (SS) and drain-induced barrier lowering (DIBL). The JLSGTFET demonstrates a small variation in DC and subthreshold parameters, indicating good prospects for future analog and digital applications. All the analysis of the proposed JLSGTFET is carried out on a 2D/3D VisualTCAD device simulator. | Low-Power Efficient p+ Si0.7Ge0.3 Pocket Junctionless SGTFET with Varying Operating Conditions | 10.1007/s11664-020-08145-3 |
2020-07-01 | Abstract A hydrogeochemical and isotopic study was conducted in the western portion of the Celaya Valley Aquifer, Mexico, to assess the role of dissolved carbon dioxide in groundwater contamination. The partial pressure of carbon dioxide value is used to evaluate a complex hydrogeochemical environment, and the carbon dioxide behavior is used to identify the natural and anthropogenic processes related to pollution sources in a thermal aquifer located in the western portion of the Celaya Valley Aquifer. Results indicate that during groundwater migration from the recharge zone to the center of the basin, a hydrogeochemical evolution from calcium bicarbonated and calcium–bicarbonate–chloride type to sodium–bicarbonate type occurs. During this process, deep fluids that migrate through the fault system interact with the aquifer; these fluids contain carbon dioxide released from the metamorphism of the carbonated basement, although another source is not discarded as the dissolved inorganic carbon typical of meteoric groundwater produced from atmospheric carbon dioxide. The hydrogeochemical and isotopic evidences of delta carbon thirteen, delta oxygen eighteen and delta deuterium indicate that the dissolved content of carbon dioxide in the aquifer is involved in the silicate weathering process that plays a major role during water type evolution. In some cases, during weathering, potentially toxic elements are released in amounts that represent an environmental risk, among which arsenic and fluoride stand out, mainly in depth wells. Additionally, other isotopic and hydrogeochemical evidence indicates a biological source of carbon dioxide in the shallow aquifer, primarily due to the agricultural activity carried out in the entire study area. Graphic abstract | Evaluation of the carbon dioxide behavior in a thermal aquifer located at Central Mexico and its relation to silicate weathering | 10.1007/s13762-020-02683-3 |
2020-07-01 | Abstract The paper analyzes the nucleation and growth of bainite in low-carbon low-alloy 09Mn2Si steel doped with titanium carbonitride nanoparticles in impact toughness testing. The analysis shows that such particles segregate at low-angle boundaries, retarding the formation of high-angle ones, and when impacted into the steel, they curve the lattice and generate a new bainite phase at the curvature interstices. The mechanism of bainite nucleation and growth is sympathetic, obeys the angular momentum conservation law, and provides the formation of multilayered packets of bainite plates capable for unlimited thinning to sub-sub-subunits during deformation. Such bainite plates can respond to their stress-strain state by one or another rotation, showing a high relaxation capacity and providing a high impact toughness of the steel at low temperatures. | Hardening Mechanism in Low-Carbon Low-Alloy Steels with a
Simultaneous Increase in Ductility and Fracture Toughness | 10.1134/S1029959920040098 |
2020-07-01 | A high-building multi-directional pipe joint (HBMDPJ) was fabricated by wire and arc additive manufacturing using high-strength low-alloy (HSLA) steel. The microstructure characteristics and transformation were observed and analyzed. The results show that the forming part includes four regions. The solidification zone solidifies as typical columnar crystals from a molten pool. The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100°C, and the typical columnar crystals in this zone are difficult to observe. The partial austenitizing zone forms from the completely austenite zone heated between Ac1 (austenite transition temperature) and 1100°C, which is mainly equiaxed grains. After several thermal cycles, the partial austenitizing zone transforms to the tempering zone, which consistes of fully equiaxed grains. From the solidification zone to the tempering zone, the average grain size decreases from 75 to 20 µm. The mechanical properties of HBMDPJ satisfies the requirement for the intended application. | Microstructure and mechanical properties of high-strength low alloy steel by wire and arc additive manufacturing | 10.1007/s12613-019-1919-1 |
2020-07-01 | This study investigated the applicability of low transformation temperature (LTT) arc welding consumables to improve fatigue strength against weld root failure. Transverse attachment joints formed by single-sided welding, similar to rib-to-deck connections in orthotropic steel bridge decks, were fabricated using an LTT welding consumable and conventional welding consumable. Fatigue tests were performed with out-of-plane bending loads using a vibration-type fatigue testing machine. The test results indicated that higher fatigue strength can be achieved in the joint with an LTT consumable compared with a conventional one. In addition, residual stresses around the weld bead were clarified by X-ray diffraction measurements and finite element analyses. The results revealed that the LTT consumable weld metal can reduce residual stress around the weld and also introduce compressive residual stress to the weld root, which can contribute to improved fatigue strength. | Fatigue strength of transverse attachment steel joints with single-sided arc weld using low transformation temperature welding consumable | 10.1007/s40194-020-00915-1 |
2020-07-01 | Abstract The change in mechanical properties due to low temperatures and the associated damage are studied for various metals. Cracks in austenitic steel are found to be due to large carbides, nitrides, and carbonitrides. The time for a brittle crack to propagate in metal depends on the grain size, the elastic modulus and the density. | Low-Temperature Damage to Metals | 10.3103/S1068798X20070175 |
2020-07-01 | Abstract The reasons for the fall in the discharge capacity of the LiMn 2 O 4 spinel composition with a Norit carbon filler in the redox reaction with lithium at a temperature of 271 K were analyzed using cyclic voltammetry and impedance spectroscopy. A comparison is made between the electrochemical behavior of LiMn 2 O 4 –Norit compositions, LiMn 2 O 4 compositions with carbon nanotubes, and LiMn 2 O 4 compositions with natural EUZ–M graphite to identify the key factors responsible for the efficient transformation of the composite electrodes under study in the prototype lithium battery. | LiMn2O4–Norit at a Low Temperature in Comparison with LiMn2O4—MWCNT and LiMn2O4–EUZ–М Graphite in the Prototype Li-Battery | 10.3103/S106837552004002X |
2020-07-01 | This study predicts numerically the performance of low-GWP refrigerants [R152a, R1234yf and R1234ze(E)] as an alternative to R134a in a vapor compression refrigeration system. The plate heat exchanger was used as a condenser, and the appropriate correlations available in the published literature were used to predict the heat transfer coefficients and friction factors of refrigerants during condensation. Drop-in analysis based on the same conditions of the cooling medium (water) was considered, and the system was modeled in EES software. For this analysis, the inlet temperature of the water was varied from 15 to 40 °C as an input, and its effect on the performance parameters (condensation temperature, input power, discharge temperature, compression ratio, cooling capacity and COP) was analyzed and compared with R134a. The correlation used in this study predicts the better performance of R152a and R1234ze(E) as their heat transfer coefficient values are found to be 67–72% and 0.85–3% higher at condensation temperatures of 40–55 °C, respectively, when compared with R134a. The trends for the predicted frictional pressure drops are also found to be similar. For the drop-in analysis based on the same cooling medium conditions, simulation results reveal better performance for R152a and R1234ze(E). R152a shows 6.3–11% higher COP relative to R134a, whereas R1234yf shows lower COP of 7.6–12%, for the range of cooling water inlet temperatures considered in this study. Simulation results conclude that R152a seems more adequate refrigerant as an alternative of R134a in vapor compression refrigeration system. | Comparative Performance of Low-GWP Refrigerants as Substitutes for R134a in a Vapor Compression Refrigeration System | 10.1007/s13369-020-04525-3 |
2020-07-01 | In this research, combustion behaviour of three crude oils with different °API gravities was analysed. The thermogravimetric analyser (TGA) and differential scanning calorimeter (DSC) experiments were performed using three different heating rates (2, 5, and 10 °C min −1 ) under air atmosphere. The reaction regions, burn-out temperatures, and peak temperatures were determined accordingly. Two main reaction regions, particularly the low-temperature oxidation (LTO) and high-temperature oxidation (HTO) reactions, were figured out in TGA and DSC curves, which suggested exothermic behaviour. Kinetic parameters of the crude oils were determined using model free methods (Ozawa–Flynn–Wall, OFW, and Kissinger–Akahira–Sunose, KAS), which allows the calculation of kinetic properties at progressive conversion degrees without the requirement of any reaction models and f ( α ) estimations. The variation in activation energy with respect to the conversion degree pointed out that the LTO reaction stage can be subdivided into three subzones. The results indicated that the activation energies were changing depending on the conversion degree, which is an indication of complex reaction mechanisms. The change in activation energy with respect to conversion degree showed slight variation for heavy crude oil compared with that in light crude oil. | Low-temperature oxidation reactions of crude oils using TGA–DSC techniques | 10.1007/s10973-019-09066-y |
2020-07-01 | Abstract The issue of the formation of the compound composition of low-molecular-weight organic compounds in aquatic macrophytes, which make up their low-molecular-weight metabolism, has hardly been studied when introducing them into new habitats. The study aims to compare the component composition of the low-molecular-weight metabolome of sago pondweed ( Potamogeton pectinatus L.) on the low-molecular-weight organic compounds contained in the essential oil from the invasive population in the Lake Ladoga and the populations from the native range in Astrakhan Region, Russia. Gas chromatography–mass spectrometry was the major research method. Upon the invasion of P. pectinatus into Lake Ladoga, there was a change in the content of various groups of low-molecular-weight organic compounds in the essential oil and a change in the complex of major components. Fatty acids (29.3–40.0%) and ketones (14.5–18.5%) prevailed in the low-molecular-weight metabolome of sago pondweed in the lakes of the native range. Ketones (27.4%) and aldehydes (18.1%) were the main groups in this species inhabiting Lake Ladoga. About a third of the compounds in the composition of the low-molecular-weight metabolome were specific both to the invasive population of the sago pondweed in the Lake Ladoga and to the population from the lakes of the native range. The plasticity of the metabolism of P. pectinatus allows it to adapt to a wide spectrum of abiotic conditions and different biological environments and to settle in new habitats, primarily those under anthropogenic impact. | Change of Low-Molecular-Weight Metabolome of Alien Species Potamogeton pectinatus L. in Lake Ladoga in Comparison with Population of Native Range | 10.1134/S2075111720030066 |
2020-07-01 | Compositions, technology features, and the main properties of cement-free refractory concretes (CFRC) based on a silica-sol binder are considered. Concretes of high-alumina and corundum compositions of CFRC, as well as in the Al 2 O 3 –SiO 2 –SiC–C system predominate in this group. Improved thermal and thermomechanical properties of CFRC compared with the properties of LCRC are largely due to mullitization as a result of interaction of nanodispersed SiO 2 (silica sol and microsilica) with reactive alumina of the matrix system. Extensive and effective use of CFRC based on silica binders is achieved in blast furnace production (chutes, cold and hot shotcreted blast furnace shafts) and for lining cement production furnaces. | Cement-Free Refractory Concretes. Part 4. Refractory Concretes based on Silica Sol Binders | 10.1007/s11148-020-00447-7 |
2020-07-01 | Abstract Austenitic stainless steels (ASSs) offer many advantages over carbon and/or graphite composites for bipolar plates of proton exchange membrane fuel cells (PEMFCs). However, its corrosion resistance in PEMFCs operating conditions is lower. A low temperature (450°C) salt bath nitriding technique for different durations (3, 6 and 12 h) was employed to modify the surface of 316L ASS to enhance its corrosion resistance. The scanning electron microscopy of the transverse sections of nitrided sample reveals a white layer and its thickness increases on increasing nitriding durations. The X-ray photon spectroscopy results show that on nitriding, nitrogen (N) is present in the free form (on 3 h duration) and nitrides (CrN and Fe x N) precipitates (on 6 and 12 h durations). The corrosion resistance increased on nitridation. The best corrosion resistance was obtained for 3 h nitriding. The corrosion resistance decreases on increasing durations which can be attributed to the formation of nitrides. | Influence of Time on Low Temperature Salt Bath Nitriding and its Corrosion Behavior of 316L ASS in PEMFC Environment | 10.1134/S2070205120040243 |
2020-07-01 | In this paper, T-joint samples in a 1300 MPa yield strength steel were produced using conventional or low transformation temperature (LTT) type consumables. The welded samples were either subjected to high-frequency mechanical impact (HFMI) treatment or to shot-peening. Fatigue testing was performed under fully reversed, constant amplitude bending load. Shot-peening gave a significant increase in fatigue strength for more than around 50,000 cycles. Shot-peened LTT welds had the highest fatigue strength, with conventional welds being shot-peened having slightly lower fatigue strength. HFMI treatment of conventional and LTT welds improved the fatigue strength also, but to a lesser extent, keeping the slope in the SN diagram close to three, while shot-peened samples had a slope of 5–7. Significant differences in compressive residual stress were seen between the different welds, with the most compressive stress found in the shot-peened samples. This was probably one of the main reasons for the improved fatigue life of shot-peened samples. | Comparison of effect of shot-peening with HFMI treatment or use of LTT consumables on fatigue strength of 1300 MPa yield strength steel weldments | 10.1007/s40194-020-00917-z |
2020-07-01 | (7 R ,8 S )-diaminopelargonic acid transaminase from the cold-adapted Gram-negative bacterium Psychrobacter cryohalolentis ( Pcryo361 ) is able to react with unnatural substrates including ( S )-( +)-1-phenylethylamine, aldehydes and α-diketones. Additionally, Pcryo361 is active at 0–50 °C and retains up to 10% of the maximum activity at 0 °C. Here, we report a detailed study on the stability and low temperature activity of Pcryo361 . At the optimal pH for ( S )-amine activity (pH 10.0), the enzyme was stable at 0–10 °C and no decrease in the enzyme activity was observed within 24 h in a slightly alkaline medium, pH 8.0, at 35 °C. Pcryo361 was solvent stable and was activated in 10% DMSO and DMFA at 35 °C. An analysis of the efficiency of catalysis of Pcryo361 at 35 °C and 10 °C showed that the specificity towards ( S )-( +)-1-phenylethylamine dropped at 10 °C; however, the specificity towards 2,3-butanedione remained unchanged. Inhibition analysis showed that Pcryo361 activity was not inhibited by acetophenone but inhibited by amines (products of aldehyde amination). The observed pH stability and low temperature activity of Pcryo361 with activated keto substrates are attractive features in the field of development of stereoselective amination at low temperatures. | Effects of pH and temperature on (S)-amine activity of transaminase from the cold-adapted bacterium Psychrobacter cryohalolentis | 10.1007/s00792-020-01174-0 |
2020-07-01 | Laboratory simulation of recrystallization annealing in continuously operating units is performed for rolled IF-steels of nine different compositions of laboratory and industrial melting. It is established that by controlling parameters of low-temperature processing regimes in a CAU and CHGU, it is possible to improve ductility and formability of rolled IF-steels significantly. During annealing rolled products in a CHGU it is possible to reduce the intensity of aging processes and prevent a reduction in ductility and formability using a strip temperature at the exit of the accelerated cooling section (P6) of at least 540°C, as well as a strip temperature at the exit from the cooling section after the galvanizing bath (P10) of not more than 180°C. This is especially relevant for IF-steels with a low sulfur content, when the possibility of stabilizing carbon in the form of titanium carbosulfide is limited. During annealing in a CAU rolled products from fully stabilized IF steels are slightly sensitive to overageing temperature regime. With incomplete stabilization of carbon in IF-steels, due to a low titanium concentration, its removal from solid solution in the form of cementite precipitates and the improvement of ductility and formability of rolled products is possible when using an overageing regime of 420–330°С, and especially at 390–300°С. Removal of carbon from the solid solution may be prevented by a high phosphorus concentration (≈ 0.011 wt.%) in steel. In this case, complete stabilization of IF steel is necessary by increasing titanium and/or niobium concentration. | Study of the Effect of Recrystallization Annealing Regimes in Continuous Operating Units on the State of If-Steel Solid Solution and Mechanical Properties | 10.1007/s11015-020-01000-0 |
2020-07-01 | Abstract A relatively new approach to obtaining metal materials containing several principal elements in equiatomic concentrations which look promising for replacing commercially used alloys is proposed. Such materials are called high-entropy alloys (HEAs). Studies show that HEAs tend to form a simple solid-solution structure and can also contain ordered intermetallic phases. Such a method of forming metal materials can be regarded as a background for producing new HEAs with elevated performance characteristics. Most studies focus on the relationship between microstructure and measured properties; significantly less attention is paid to studying and developing new effective methods for creating HEAs. In this paper, we study the possibility of obtaining CoCrFeNiMn–(X) HEAs by centrifugal metallothermic SHS. Chemical and technological modes of modifying cast CoCrFeNiMn alloy during synthesis (in situ) by introducing alloying components into the starting exothermic compositions are tested for the first time. The microstructure and phase composition of NiCrCoFeMn alloys synthesized from mixtures containing Ti–Si–B(C) or Al are characterized. The microstructure of CoCrFeNiMn–(Ti–Si–B(C)) HEAs is found to consist of an HEA-based matrix and new structural inclusions of carbides and borides of titanium. High-Al CoCrFeNiMn–Al HEAs are represented by a composite structure containing NiAl as a basis and dispersion nanoprecipitates (~100 nm) of a Cr- and Fe-based solid solution. | Centrifugal Metallothermic SHS of Cast Co–Cr–Fe–Ni–Mn–(Х) Alloys | 10.3103/S1067821220040070 |
2020-07-01 | Cleanliness of aluminum-killed ultra-low carbon steel produced through BOF–RH–CC and BOF–LF–RH–CC was comparatively investigated by nitrogen–oxygen analysis, SEM analysis and thermodynamic calculation to seek for an optimum refining process. The results show that the non-metallic inclusions with area above 8 μm 2 could be removed obviously in both the refining processes. Compared with BOF–RH–CC process, in RH refining stage, the size of inclusion and total oxygen control were better than the original process. Furthermore, BOF–LF–RH–CC process reduced the inclusion area ratio, the proportion of single inclusion area of < 8 μm 2 increased from 85 to 95%, the proportion of Al 2 O 3 inclusion less than 5 μm 2 increased from 50 to 70%. Meanwhile, the desulfurization effect became pronounced and the temperature control of the double refining process was more stable than that of the original process. | Comparative Study on the Cleanliness of Ultra-low Carbon Al-Killed Steel by Different Refining Processes | 10.1007/s12666-020-01988-8 |
2020-07-01 | We have combined new titanite, zircon, and apatite fission-track and apatite [U–Th–(Sm)]/He analyses with previously published U–Pb, Rb–Sr, and 40 Ar/ 39 Ar thermochronological data to reconstruct the Cenozoic thermal evolution of the Central Rhodope Metamorphic Complex (CRMC), exposed mainly in southern Bulgaria and to a lesser extent in northern Greece. Results reveal two phases of cooling. During the first phase, between ~ 37 and ~ 33 Ma, the CRMC experienced rapid cooling from partial melting at > 650 °C to ca 60 °C. Multiple generations of low-angle ductile-to-brittle fault zones accommodated the exhumation of the migmatitic core together with parts of its high-grade periphery. Oligocene volcanism and associated local elevation of the geothermal gradient is responsible for the resetting of some fission-track ages in the CRMC. The second cooling phase to temperatures of about 40 °C, between 24 and 13 Ma, is related to exhumation along high-angle normal faults in the southern part of the CRMC. | Cenozoic thermal evolution of the Central Rhodope Metamorphic Complex (Southern Bulgaria) | 10.1007/s00531-020-01862-4 |
2020-07-01 | Abstract A phenomenological model of the kinetics of austenite decomposition of low-carbon low-alloy high-strength steels is presented. The model is based on experimentally obtained empirical dependences linking the transformation rates with the specific power of the heat flux from the metal volume and with the temperature of this volume. This model was used to implement the finite-difference scheme to solve the problem of heat conduction in a medium with internal heat release sources. The digital twin of the cooling process, which includes the specified calculation procedure, is integrated into the TLS 5000 automation system of PAO Magnitogorsk Iron and Steel Works. The determined mass fractions of austenite decomposition products are used for both the design certification of the structural state of rolled products and the construction of statistical models to predict mechanical properties. | Phenomenological Model of Austenite Decomposition Kinetics in Low-Carbon Low-Alloy High-Strength Steels | 10.3103/S0967091220070153 |
2020-07-01 | A study has been made of the activation energy of the conductance of a p – n -4H-SiC 〈Al〉 structure created through the doping of silicon carbide with aluminum. The doping was implemented by a novel method of low-temperature diffusion, in which the diffusion of aluminum in silicon carbide is stimulated by a carbon- and silicon-vacancy flux produced by the oxidation of the silicon surface. | Activation Energy of the Conductance of p–n-4H-SiC 〈Al〉 Structures Doped with Aluminum by the Method of Low-Temperature Diffusion | 10.1007/s10891-020-02205-5 |
2020-07-01 | The refrigerator unit based on electrically driven vapor compression technology consumes high energy, associated with high cost and loss of ecosystem. Recently, solar thermal energy emerges as a key research area and introducing it in refrigerator application has happened extremely fast. Solar thermal refrigeration systems based on ejector compression technology are thriving because of its utilization of low-grade energy sources, straight forward design, non-moving parts, lower maintenance costs, and durability. In this present work, the performance of a solar ejector refrigeration system (ERS) is calculated analytically using one-dimensional model. The performance parameters are calculated with the assumption that both the condensation and evaporation processes occur along the saturation line. Initially, the influence of the ejector area ratio, generator temperature, condenser temperature, and evaporator temperature on the performance of the ERS is analyzed in critical mode with water (R718) as the working fluid. The analysis shows that the coefficient of performance increases more than two times on increasing the ejector area ratio from 6.4 to 12.8. The results also show that a higher coefficient of performance (COP) is obtained at a higher ejector area ratio. The COP is found to be inversely related to the generator temperature, meanwhile the coefficient of performance increase more than 74% on increasing the refrigeration temperature from T c = 8 °C to T c = 15 °C. Then, the performance of ERS is obtained at the subcritical conditions at varying generator temperatures. At subcritical mode, COP is found to be directly proportional to the generator temperature, and the highest COP occurs at an optimum generator temperature. The performance of the ERS with various refrigerants as R717, R718, R245fa, R123, R141b, and R365fa is calculated at the critical mode. With refrigerant R717, the system shows higher performance as well as a cooling effect than other refrigerants. However, most environmental benign refrigerant R718 shows comparatively low performance, but it is found that R718 produces a significant cooling effect than other refrigerants excluding R717 refrigerant. | Performance of ejector refrigeration cycle based on solar energy working with various refrigerants | 10.1007/s10973-020-09319-1 |
2020-07-01 | Polyamide 6 (PA6) is a polymer largely applied in the packing industry; however, it has limitations like high water absorption, notch-sensitive impact and high electrical resistance. Some strategies have been developed aiming to improve these drawbacks, as blending PA6 with other polymers, like linear low-density polyethylene (LLDPE) which is also an electrical insulator. In this work, antistatic packages for the transportation and storage of electronic devices were prepared by mixing PA6 and LLDPE with the addition of carbon black as an antistatic agent to reduce the electrical resistivity of polymers. PA6/LLDPE (50/50) blend-based carbon black composites with different contents of carbon black (5, 10 and 15 wt%) were prepared in a twin screw extruder, and their mechanical, rheological, electrical and permeation properties were studied. Thereby, the effects of the addition of maleic anhydride-grafted LLDPE (LLDPE- g -MA) in the composites were also studied. The addition of LLDPE- g -MA and 5 wt% and 10 wt% of carbon black in the PA6/LLDPE blend resulted in a 130 and 150% increase in impact strength, respectively. Adding 10 wt% of carbon black in the PA6/LLDPE/LLDPE- g -MA blend increased the elastic modulus, reduced the electrical resistivity by 14 decades and also reduced the water vapor permeability, allowing this material to be eligible for use as antistatic packaging. | Development of antistatic packaging of polyamide 6/linear low-density polyethylene blends-based carbon black composites | 10.1007/s00289-019-02928-3 |
2020-07-01 | The tetragonal crystalline form of boron nitride remains in theoretical prediction stage till date without being synthesized in real practice and in accordance; properties could not be verified experimentally. Here we synthesize tetragonal boron nitride through a low-cost chemical synthesis route for the first time along with thermodynamic analysis and identification of evolved product gases through gas chromatography to authenticate the chemical reaction feasibility. The evolution of tetragonal boron nitride is substantiated with XRD analysis, Raman spectroscopy, x-ray photoelectron spectroscopy and FEG-TEM based SADP and EDS analysis together with IFFT micrograph-based measurement of the interplanar spacing of dominating (110) growth plane. The experimentally measured lattice parameters ( a = 0.4378 nm, c = 0.2541 nm) closely match with those predicted theoretically ( a = 0.4380 nm, c = 0.2540 nm). The presence of sp 3 bonding in synthesized material is also confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy. Furthermore, we determine some significant properties of synthesized tetragonal boron nitride that envisage large optical band gap (5.66 eV), low electrical conductivity (671 S m −1 ) of semiconducting range, low density (1.83 g cm −3 ), high hardness (28 GPa) and the highest specific hardness (15.30 GPa/g cm −3 ) among other forms of polycrystalline boron nitride and commonly used hard ceramic materials. Accordingly, a new dimension is hereby added to material development for electronic/optoelectronic applications as well as in low-density hard structural material synthesis in view of using tetragonal boron nitride as reinforcement for metal matrix composites. | Advent of a Wide-Band-Gap Semiconducting Low-Density Material Possessing Significantly High Specific Hardness | 10.1007/s11665-020-04915-6 |
2020-07-01 | Abstract A material in the form of a multilayer structure based on low-temperature LT-GaAs grown on (111)A-oriented substrates is proposed for fabrication of THz photoconductive antennas. These structures contain active LT-GaAs layers and doping acceptor GaAs:Si-based layers. At the optical pump power of 19 mW and the bias voltage of 30 V, a photoconductive antenna based on the optimized {LT-GaAs/GaAs:Si} (111)A structure emits THz pulses with the average power of 2.3 μW at the pulse repetition frequency of 80 MHz; the conversion efficiency is 1.2 × 10 –4 . It is shown that the dependence of the integral power of THz pulses of the antenna based on the {LT-GaAs/GaAs:Si} (111)A structure on the applied voltage is superlinear; the dependence of this parameter on the optical pump power is plotted as a curve with saturation. It is shown that the designed antennas have a practical application in THz spectroscopy of biological solutions. | THz Radiation of Photoconductive Antennas based on {LT-GaAa/GaAa:Si} Superlattice Structures | 10.1134/S0030400X20070097 |
2020-07-01 | The properties of steel parts after carburizing in low-pressure acetylene are studied. The thickness of the carburized layer, its hardness, the microstructure, and the hardness of the core are determined after carburizing at 900 – 960°C with simultaneous shortening of the process from 104 to 44 min. The data obtained for the diffusion of carbon make it possible to predict the profiles of carbon distribution over the thickness with good enough accuracy. | Influence of the Temperature of Vacuum Carburizing on the Thickness of the Carburized Layer and Properties of Steel Parts | 10.1007/s11041-020-00549-6 |
2020-07-01 | The present study has investigated the effect of changes in accelerated cooling (ACC) and finish rolling temperature (FRT) on the mechanical properties of high-strength low-alloy (HSLA) Nb-V-Ti steel plate of non-sour API 5LX70 linepipe during the thermomechanical controlled process (TMCP). Tensile test results showed that increasing ACC or reducing FRT enhanced yield and tensile strengths of the subject steel, which was also confirmed by the Vickers hardness test. Microstructure examinations demonstrated that increasing ACC and reducing FRT resulted in a lower volume fraction and a finer size of pearlite. Moreover, an increase in the ACC enhanced the formation of granular ferrite (GF) and fine polygonal ferrite (FPF), while a decrease in the FRT mostly affected the formation of acicular ferrite (AF). In all microstructures, banded structures and particles with a size of approximately 6 μm were observed due to segregation during solidification, where changing the parameters did not affect their formations. | Effect of Cooling Rate and Finish Rolling Temperature on Structure and Strength of API 5LX70 Linepipe Steel Plate | 10.1007/s11665-020-04961-0 |
2020-07-01 | Abstract Cellulose nanocrystals (CNCs) were surface modified with 3-isocyanatopropyl triethoxysilane (ICPTS) in tetrahydrofuran at 62–63 °C using triethylamine as a catalyst. ICPTS modified CNCs were further studied as a nanofiller in nanocomposites with linear low-density poly(ethylene) (LLDPE) prepared by melt processing. The modification of CNCs was confirmed by FTIR, solid state NMR, and thermogravimetric analysis. Compared to unmodified CNCs, the ICPTS modified CNCs show enhanced compatibility with LLDPE as shown by SEM. Nanocomposites processed at 70 °C reveal slightly enhanced mechanical properties and this effect was further intensified by increasing the molding temperature up to 120 °C. Under such conditions, a 20% increase in Young’s modulus and 30% increase in tensile strength are achieved compared to neat LLDPE. Differential scanning calorimetry confirms the degree of LLDPE crystallinity, beside the CNC reinforcing network formation, as an important decisive factor in defining the final mechanical properties of LLDPE/CNC nanocomposites. The maximal enhancement of mechanical properties was observed at rather low amount of added ICPTS modified CNC (1–2 wt.%), which is important for practical application as CNCs are still rather expensive nanofiller. By modification of CNC with ICPTS the CNC polarity is reduced, which result in their improved compatibility with LLDPE, while on the other hand they function as a plasticizer and thus reduce the LLDPE crystallization degree, especially at high CNC concentrations. Graphic abstract | Silane modified cellulose nanocrystals and nanocomposites with LLDPE prepared by melt processing | 10.1007/s10570-020-03181-y |
2020-07-01 | A series of Ho-modified Mn/Ti catalysts with various content of Ho were prepared by impregnation method, and the low-temperature catalytic performance was tested. Techniques of BET, SEM, XRD, H 2 -TPR, and XPS were carried out to research the effects of Ho modification on the physicochemical properties of Mn/Ti catalysts. Results showed that appropriate Ho addition could reduce the starting temperature of Mn/TiO 2 catalyst to 100 °C. 0.2HoMn/Ti exhibiting a wider temperature range of 140~220 °C with nearing 100% NO x conversion. It was found that the 0.2HoMn/TiO 2 catalyst possessed a better dispersion of active component, enhanced redox capacity, a higher concentration of Mn 4+ species, and a larger amount of O β content on the catalyst surface, which are all likely predominant factors related to the excellent SCR activity. Additionally, Ho improved the Lewis acid sites and enhanced the adsorption and activation ability of NH 3 , as well as the NO to NO 2 oxidation ability. The selective catalytic reduction with ammonia (NH 3 -SCR) deNO x mechanism over HoMn/Ti catalysts obeyed both the Eley–Rideal (E-R) and Langmuir–Hinshelwood (L-H) mechanisms under low-temperature reaction conditions. | Improved activity of Ho-modified Mn/Ti catalysts for the selective catalytic reduction of NO with NH3 | 10.1007/s11356-020-07749-w |
2020-07-01 | High-strength steel heavy plates are usually covered with a mill scale after production. Morphology, structure, and chemical composition are determined by several factors, e.g., rolling parameters, cooling rate, quenching method, and alloying elements. As the mill scale might cause pore formation and process instability, it is preferably removed prior to welding. In welding practice, the removal of scale is in many cases insufficient and can lead to welding defects. In this paper, the influence of a scale layer on the weld bead geometry and thermal cycle during GTA welding is analyzed. Several high-strength steels with different chemical compositions and plate thicknesses have been used for bead-on-plate welding. The influence of mill scale on penetration depth and cooling time is analyzed and a connection to the varying fluid flow in the weld pool is drawn. | Influence of mill scale on weld bead geometry and thermal cycle during GTA welding of high-strength steels | 10.1007/s40194-020-00910-6 |
2020-07-01 | The article considers a method for extracting xenon from gas concentrates on the basis of batch adsorption separation. An experimental unit for studying xenon adsorption dynamics at cryogenic temperatures was developed. Simulations were carried out in order to investigate the process of xenon adsorption from an air separation unit (ASU) “safety stream” on different sorbent materials (four types of silica gel and active aluminum oxide). A krypton-nitrogen-helium (Kr-N2-He) mixture was selected for the purposes of modeling to comply with fire and explosion safety requirements and to reduce the duration of the experiment. From analyzing the data obtained using the described, specially-developed experimental technique, we selected the sorbent having the maximum dynamic capacity for our application. | Investigation of Xenon Extraction from ASU Streams by Low-Temperature Adsorption | 10.1007/s10556-020-00770-3 |
2020-07-01 | A surface layer of steel/SiC nanocomposite was fabricated by multiple passes of friction stir processing (FSP) on a low-carbon steel. The characterization methods such as optical microscopy, field emission scanning electron microscopy, microhardness, and wear test were performed to obtain the microstructure and mechanical properties of the produced layers. The results revealed that the dispersion of nano-SiC particles is directly related to the FSP passes and that the superior scattering of the nanosized SiC particles is achieved at higher FSP passes. Nano-composite surface layers demonstrated an average microhardness value of ~ 424 HV, which is ~ 3.4 times higher than that of the as-received substrate. Moreover, ultra-fine submicron grains were formed by FSP due to the role of SiC particles as obstacles to grain growth. The produced surface-layer nanocomposite exhibited an outstanding enhancement in wear resistance in comparison with the FSPed sample without reinforcing particles. | Multipass Friction Stir Processing of Steel/SiC Nanocomposite: Assessment of Microstructure and Tribological Properties | 10.1007/s11665-020-04947-y |
2020-07-01 | Low-cycle fatigue properties and uniaxial ratcheting behavior of a 7050-T6 aluminum alloy were investigated by a non-symmetric cycle stress tests at the normal temperature. The low-cycle fatigue behavior of the alloy was evaluated. The effect of the stress rate, stress amplitudes, and mean stresses on its ratcheting performance was discussed. Considering the ratcheting effect and special working conditions that large mean stresses and small stress amplitudes, based on the same properties under loading, a new fatigue life prediction empirical equation was proposed to estimate the ratcheting life. The results prove that the ratcheting strain of the alloy depends on the stress amplitudes and mean stresses, whereas the stress rate almost has no effect on the ratcheting behavior on account of the rate-independent feature of the material. This equation can give a precise estimate of the ratcheting behavior of large mean stresses and their small amplitudes. | Low-Cycle Fatigue and Ratcheting Lifetime Estimation of a 7050-T6 Aluminum Alloy | 10.1007/s11223-020-00211-9 |
2020-07-01 | We propose a way to increase the wear and crack resistance of the main working tools for roller mills. Bimetallic rollers (with a diameter of 252 mm and a length of 1620 mm) are produced by sequential pouring of alloys with similar temperatures of phase transformations. The microstructure, phase composition, redistribution of alloying elements, and the properties of bimetallic materials are studied. The results are used as a basis for the development of a technological process for the production of bimetallic milling rollers by the method of centrifugal casting. The implementation of this method makes it possible to improve the reliability and durability of rollers in the course of their operation. | Structure and Properties of Bimetallic Centrifugally Cast Milling Rollers | 10.1007/s11003-020-00397-y |
2020-07-01 | 1,2,3,4-Butanetetracarboxylic acid (BTCA) can impart good anti-wrinkle properties to treated cotton fabrics, but it also causes significant strength loss. In this paper, maleic acid (MA) and acrylic acid (AA) were employed to synthesize a low-molecular-weight copolymer (P(MA–AA)) for the anti-wrinkle finishing of cotton fabrics with the hope of reducing strength loss. The best molar ratio of MA:AA and reaction time were 2.5:1 and 5 h, respectively. The molecular weight of P(MA–AA) was determined via mass spectroscopy as 376, and the copolymer consisted of two MA and two AA molecules. The recommended anti-wrinkle finishing conditions were 140 g/L P(MA–AA), finishing bath pH of 1.8, curing temperature of 180 °C and curing time of 2 min. Consequently, the P(MA–AA) showed an outstanding finishing effect on cotton fabrics, compared with BTCA, MA, and citric acid treatments. Additionally, the P(MA–AA)-treated fabrics achieved a wrinkle recovery angle, tearing strength retention, and whiteness index of 255.1° ± 3.50°, 51.2, and 76.20%, respectively. This indicates that P(MA–AA) has a potential for industrial applications. | Synthesis of a low-molecular-weight copolymer by maleic acid and acrylic acid and its application for the functional modification of cellulose | 10.1007/s10570-020-03201-x |
2020-07-01 | Green chemistry is developing to invent new reactions that are cheaper, cleaner and use less energy. Acetalization is a common strategy for the protection of aldehydes in synthetic chemistry, yet actual protocols of acetals synthesis are limited by difficult workups, the use of high-loading catalyst, harsh reaction conditions, and catalyst tedious preparation. Alternatively, photocatalysis allows to access functional products with minimum synthetic procedures and waste generation. Here we use sodium 4-[6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl]benzene-1,3-disulfonate (acid red 52) as photocatalyst under yellow light irradiation. We obtained a wide array of acyclic and cyclic acetals in 75–93% yields. Results show the efficient acetalization of aldehydes with alcohols at room temperature, the use of abundant and sustainable alcohols as both the solvents and coupling agents, low catalyst loading, short reaction time, and readily available catalyst, which might be applied to green-catalyzed systems. | Green chemistry: efficient acetalization of aldehydes with alcohols using the acid red 52 photocatalyst | 10.1007/s10311-020-00994-y |
2020-07-01 | The post-orogenic evolution of the European Variscan basement remains difficult to constrain due to the absence of post-orogenic sedimentary records. One of the current ways to access this history is to constrain the thermal evolution of these basement areas through indirect methods such as low-temperature thermochronology (LTT) thermal modelling. In this study, apatite fission-track (AFT) data have been acquired for the north-eastern part (Vendée and Limousin) of the French Massif Central Variscan basement. Similar thermal inversion procedure has been done, assuming that some samples were close to the surface during Triassic times. The results show a complex post-Variscan evolution of the western part of the Massif Central. Inversion of the AFT data indicates a high-temperature event during the Jurassic period. This thermal event can be interpreted as the deposition of a significant sedimentary cover which has been later eroded during the Late Jurassic and/or Early Cretaceous. Interpretation of the thermal models implies the presence of the sampled rocks close to the surface during Cretaceous and Eocene times. The estimated volume of this eroded sedimentary cover suggests a probable larger extension of the surrounding sedimentary basins (Paris Basin and Aquitaine Basin) across the Variscan basement area. | Lower Cretaceous inversion of the European Variscan basement: record from the Vendée and Limousin (France) | 10.1007/s00531-020-01875-z |
2020-07-01 | In the present study, the Fe-Al-based compositions developed as low-density steel are subjected to addition of Cr and Mn to increase the elastic modulus. In this regard, Fe-3.7Al-3.1Mn and Fe-6.5Al-6.3Cr steels are produced via melting and casting. The steels are cold-rolled to 98% thickness reduction followed by subsequent annealing at 750 °C. A detailed characterization based on x-ray diffraction and electron back-scattering diffraction shows the stabilization of ferrite phase upon the addition of Cr and Mn with a further reduction in density. The expansion of the lattice is observed after ternary alloying additions. The increase in the yield stress and ultimate tensile strength is noticed upon ternary alloying additions. The Cr and Mn addition also led to an increase in the elastic modulus compared to binary Fe-Al low-density steels. | Effect of Cr and Mn Addition on the Microstructure, Texture, and Mechanical Properties of Ternary Low-Density Steels | 10.1007/s11665-020-04930-7 |
2020-07-01 | Abstract Self-crosslinking styrene-acrylic latexes functionalized with 3-isopropenyl-α,α-dimethyl benzyl isocyanate (TMI) by semibatch emulsion polymerization were prepared. Polymerizations were performed in emulsions with aerosol EF-800 surfactant; remarkable colloidal stability of the copolymer latexes was measured in fresh and aged samples. The effects on film formation, tensile properties, permeability to water vapor, and oxygen were evaluated by varying the TMI concentrations (from 0 to 6 wt%). The obtained latexes were used as binder to prepare water-based coatings, which were applied on steel specimens; hydrolysis of TMI acts as a self-crosslinked promoter once the film was applied. Adhesion tests, scratch hardness, and gloss properties were evaluated. Graphic abstract Water vapor permeability of latex films | Synthesis of butyl acrylate–styrene–TMI latexes and their application as water-based coatings | 10.1007/s11998-020-00325-4 |
2020-07-01 | Abstract The influence of polar particle centers, in particular, halogen ions adsorbed on the surface of a reactor, and water molecules present in pores and microcracks on the reactor surface on the low-temperature oxidation of hydrogen and organic compounds was simulated. Within the framework of a proposed model, it was shown by appropriate calculations that the presence of the above particles in the near-surface layer promotes the conversion of H 2 O 2 molecules (an intermediate product of the oxidation of hydrogen and organic compounds) into ozone molecules. The presence of ozone molecules in the reaction system can cause changes in the reaction mechanism and thermal regime of the occurring chain process, in particular, the appearance of a pulsation process mode or burst of radiation in the reactor due to abrupt temperature fluctuations. The experimentally observed pulsation changes in the radiation of the reaction medium during the oxidation of propane under conditions of increasing the reactor pressure were explained. | Modeling of the Effect of Halogen Ions Adsorbed on the Surface of a Reactor in a Complex with Water Molecules upon the Chain Oxidation of Propane | 10.1134/S0023158420040102 |
2020-07-01 | Low temperature (LT) and Ascochyta blight are two major stresses in chickpea ( Cicer arietinum L.) cultivation. After exposure to LT treatments (acclimation, LT, acclimation + LT and control conditions), we evaluated induced responses by pathogen infection in LT-sensitive (ILC533) and -tolerant (Sel96Th11439) chickpea genotypes. In relation to genotype-specific defense reactions, tolerant plants responded more effective to the infection compared to sensitive plants, particularly after an acclimation treatment. LT treatments, and in particular an acclimation treatment, induced a significant decrease in disease symptoms 7 and 14 days after inoculation. Histopathological studies showed more infection throughout the cells of the sensitive genotype under control conditions. The minimal spread of the pathogen was observed in the tolerant genotype after acclimation treatment, and the infected plants did not contain pycnidia or hyphae of the pathogen. The electrolyte leakage index (ELI) and amount of malondialdehyde (MDA) after LT treatments were less than the values compared to post pathogen infection, indicating a difference in the degree of oxidative stress. Lower levels of pathogen-induced oxidative stress (ELI and MDA) and better photosynthetic efficiency (measured as F v / F m values) show that the tolerant genotype exposed to LT treatments acclimate better to the stress conditions compared to the sensitive genotype. Higher transcript levels for the superoxide dismutase , catalase and ascorbate peroxidase were detected during pathogen infection, particularly during the acclimation treatment, which might confirm lower oxidative stress in tolerant plants compared to sensitive plants. It is concluded that LT increased the capacity for tolerance to Ascochyta blight in chickpea plants and this was correlated with the stimulation of mechanisms involved in defense responses. | Enhanced Tolerance to Ascochyta Blight in Chickpea Plants via Low Temperature Acclimation | 10.1134/S1021443720040020 |
2020-07-01 | The detection of chlorine and improvement in its detection has remained a challenge despite the use of a single pulse and a dual pulse laser induced breakdown spectroscopic technique (LIBS). In this article, we presented an alternate technique for improving the detection of chlorine (Cl) using LIBS in conjunction with an external electric filed. A comparison of the emission intensity enhancement and plasma parameters in the absence and presence of an external field has been also presented. The implication of the presented technique for the detection of Cl is much easier and inexpensive as compared with the dual pulse LIBS. | Amelioration in the Detection of Chlorine Using Electric Field Assisted LIBS | 10.1007/s11090-020-10072-4 |
2020-07-01 | Coal gasification slag (CGS) is a carbon-containing solid waste used as an adsorbent to remove low concentrations of mercury from wastewater in a series of batch tests to assess its adsorption properties and safe storage. The results showed that the adsorption of mercury on CGS was a very rapid and efficient process, and adsorption equilibrium was reached in only 10–40 min. A pseudo-second-order kinetics model provided a better fit to the equilibrium data. The adsorption capacity on CGS was just slightly below the value of active carbon. CGS showed the highest mercury removal efficiency at a solution pH of 4. Although the presence of other metal cations and anions affected the adsorption, CGS showed good selectivity for mercury ions. The adsorption of mercury was not affected by low concentrations of Cr 3+ or Cu 2+ . The negative interference of anions on the removal efficiency followed the order: Cl − >H 2 PO 4 − >CO 3 2− . The adsorption mechanism related to the functional groups included ion exchange, precipitation, coordination complexation, and surface complexation. Mercury adsorbed on CGS leached very slowly in weakly acidic or basic solution. All results of the study indicate that CGS is an economical and safe adsorbent for potential industrial applications. | Rapid removal of low concentrations of mercury from wastewater using coal gasification slag | 10.1007/s11814-020-0546-x |
2020-07-01 | Abstract Adhesive material based on low molecular copolymer of ethylene with vinyl acetate and polymer complex synthesized by radical polymerization of acrylic acid in the presence of ε-caprolactam was developed. The compound of the adhesive was optimized, and the influence of composition and concentration of the complex, in addition to fine-grained filler (chalk), on the stickiness and adhesive strength of compositions to substrates of various natures being studied. It was shown that the adhesive characteristics of the developed adhesive compositions are superior to the corresponding indices of a composition based on low molecular polyethylene, which allows recommending them for application as construction mastic resins and as a base for label pastes and compounds for spraying on polymer films. | Adhesive Materials Based on Modified Low Molecular Copolymer of Ethylene with Vinyl Acetate | 10.1134/S1995421220030028 |
2020-07-01 | The high-strength low-alloy S460ML and S460N steels were chosen for underwater wet welding of dissimilar T-joints using covered electrodes. For improving the quality of joints, the temper bead welding (TBW) method was used. The application of TBW in pad welding conditions has been investigated earlier but the possibility of usage of this technique in welded joints was not analyzed. The main aim of the study was to check the influence of TBW on the hardness and structures of the heat-affected zone (HAZ) of dissimilar T-joints made in the underwater conditions. The experiments conducted showed that the technique used can reduce the susceptibility to cold cracking by decreasing the hardness in HAZ, which is a result of changes in its structure. The TBW technique reduced the hardness in the HAZ of the S460N steel by 40–50 HV10 and in S460ML by 80–100 HV10. It was also found that the changes in S460ML and S460N were much different, and therefore, the investigated technique can provide better results in the steel characterized by lower carbon equivalent Ce IIW . | Dissimilar underwater wet welding of HSLA steels | 10.1007/s00170-020-05617-y |
2020-07-01 | The effect of heat treatment on corrosion resistance of low-alloy pipe steels is investigated in relation to oilfield pipeline operating conditions. It is established that after pipe bulk heat treatment at 720 °C metal corrosion resistance increases, but at a lower temperature of 680 °C no significant change is detected. Analysis of the corresponding structural changes is performed and the main factors facilitating an increase in corrosion resistance are determined: cementite component spheroidization in the areas of pearlite or degenerated pearlite, and a reduction in dislocation density. The role of nanoscale precipitate type on pipe corrosion resistance is noted. It is established that at a higher processing temperature there is a larger fraction of ferritic precipitates. In contrast to interphase precipitates these particles do not adversely affect steel corrosion resistance. | Effect of Heat Treatment in Pipe Processing Stage on Corrosion Resistance of Micro-Alloyed Steel Hot-Rolled Products | 10.1007/s11015-020-00999-6 |
2020-07-01 | To evaluate the efficacy of group embryo culture under low-oxygen tension in benchtop incubators on human embryo development in vitro. The study was designed as a prospective, patient blind, randomized, controlled trial of a complex intervention. One hundred forty-eight women undergoing IVF were recruited in our fertility practice and randomized into two groups: intervention group (study culture strategy) or control group (control culture strategy). Intervention group embryos were cultured grouped under low-oxygen tension in benchtop incubators while control group embryos were cultured individually under atmospheric oxygen tension in large-box incubators. Using the study culture strategy, there were a significantly higher implantation rate (65.1% vs 49.2%; RR, 1.42; 95% CI, 1.17–1.73) and live birth delivery rate per embryo transfer (52.7% vs 39.5%; RR, 1.33; 95% CI, 1.02–1.75) with the first fresh embryo transfer. Cumulative implantation rate (56.7% vs 43.6%; RR, 1.30; 95% CI, 1.05–1.62) and cumulative live birth rate per embryo transfer (47.4% vs 36.2%; RR, 1.31; 95% CI, 1.01–1.69) were also statistically significantly increased in the study culture strategy. Human embryos exposed to our study culture condition strategy had statistically significant increased cumulative implantation rate and cumulative live birth rate per embryo transferred. Our findings suggest that this strategy specially favours poor quality embryos. Clinical Trial Registration Number: NCT 01904006 | Effect of Group Embryo Culture under Low-Oxygen Tension in Benchtop Incubators on Human Embryo Culture: Prospective, Randomized, Controlled Trial | 10.1007/s43032-020-00150-5 |
2020-07-01 | The present study assesses the Paenibacillus sp. D9 lipopeptide biosurfactant synthesis in cheap substrates including functional properties and applicability for varying biotechnological processes. Different experimental setups were made for oil dispersion, heavy metals removals from contaminated environments, and washing performance. The study revealed surface tension activities of 31.7–32.7 mN/m, and maximum biosurfactant yield of more than 8 g/L. Removals of 85.90%, 98.68%, 99.97%, 63.28%, 99.93%, and 94.22% were obtained for Ca, Cu, Fe, Mg, Ni, and Zn, respectively from acid mine effluents. In comparison with chemical surfactants, there was pronounced removal of heavy metals from wastewater, contaminated sands, and vegetable matter, as well as improved oil dispersing activity. A comparative study revealed that biosurfactant was more efficient (> 60%) for removal of tomato sauce and coffee stains than chemical surfactants (< 50%). Thus, lipopeptide biosurfactants are green biomolecules reducing hazards and contaminations within the environment. The future use of this lipopeptide biosurfactant is greatly promising in biotechnology. | Biotechnological Applications of Paenibacillus sp. D9 Lipopeptide Biosurfactant Produced in Low-cost Substrates | 10.1007/s12010-020-03246-5 |
2020-07-01 | Abstract Magnetite-gold hybrid magnetic nanoparticles of the dumbbell type were used to immobilize two proteins: α-chymotrypsin and the Bowman–Birk inhibitor. It is shown that under the influence of a low-frequency magnetic field (50 Hz), the activity of chymotrypsin bound in a complex with an inhibitor is drastically reduced depending on the magnetic field induction. We hypothesize that this effect is related to the aggregation of magnetic nanoparticles under the influence of a magnetic field. | Regulation of Biocatalysis with the α-Chymotrypsin–Bowman–Birk Inhibitor Pair Immobilized on Magnetite-Gold Hybrid Nanoparticles Using a Non-Heating Low-Frequency Magnetic Field | 10.3103/S0027131420040100 |
2020-07-01 | Abstract The formation of unoccupied electronic states and the boundary potential barrier during thermal deposition of tetracyanoquinodimethane (TCNQ) films to 7 nm in thickness on a (SiO 2 ) n -Si surface has been studied. The electronic characteristics of the surface under study are measured by the total current spectroscopy (TCS) using a testing electron beam with energies from 5 to 20 eV above the Fermi level. The formation of a boundary potential barrier in the (SiO 2 ) n -Si/TCNQ structure is accompanied by an increase in the work function of the surface from 4.2 ± 0.1 to 4.7 ± 0.1 eV. Using the results of the TCS experiments, the DOUS dependences of the TCNQ films have been built. To analyze the experimental DOUS dependences, the orbital energies of the TCNQ molecules are calculated by the density functional theory (DFT) at the B3LYP/6-31G(d) level with subsequent correction and the inclusion of the polarization energy of the condensed medium. In the energy range indicated above, DOUS of the TCNQ films has four main maxima. The DOUS maximum at energy 7.0 eV above E F is predominantly formed by π* orbitals. Three DOUS maxima in the energy range from 8.0 to 20 eV above E F are formed by approximately the same amount of the π* and σ* orbitals. | Propagation of Low-Energy Electrons and the Density of Unoccupied States in Ultrathin TCNQ Layers on the Oxidized Silicon Surface | 10.1134/S1063783420070112 |
2020-07-01 | Abstract Globus-M2—a new 1-Tesla spherical tokamak—was recently launched. The main features and research directions of this machine in scope of fusion–fission reactor development are described. Main results of the first experimental campaign with toroidal magnetic field up to 0.73 T and plasma current up to 0.33 MA are discussed. Significant improvement of the discharge parameters as compared to Globus-M was achieved. Plasma total stored energy higher than 7 kJ was obtained. Energy confinement time increase was consistent with predictions by spherical tokamak scalings. Toroidal Alfvén eigenmode-induced losses decrease with increase of plasma current and toroidal magnetic field. For the first time, LHCD with the toroidal wave slowing-down was successfully used at a spherical tokamak. | First Globus-M2 Results | 10.1134/S1063780X20070016 |
2020-07-01 | Abstract A comparative study has been performed for the structures of the maxima of the density of unoccupied electronic states (DOUS) in ultrathin films of the naphthalene-1,4,5,8-tetracarboxyl acid dianhydride (NTCDA) and naphthalene-1,8-dicarboxyl acid anhydride (NDCA) and two types of films based on phthalides: 3,3-diphenylphthalide (DPP) and 3,3-diphenylphthalide-4',4'-dicarboxyl acid (DPP–DCA). The structures of unoccupied electronic states of the 8–10-nm-thick films have been measured by total current spectroscopy (TCS) in the energy range from 5 to 20 eV above the Fermi level. The experimental results are analyzed by constructing the model total current spectra and the DOUS dependences using the results of calculation of the orbital energy of the molecules under study by the density functional theory (DFT) at the B3LYP/6-31G(d) level. The difference in the DOUS spectra of the NTCDA and NDCA films is the shift of the main DOUS maxima of the NTCDA film to lower energies approximately by 1 eV at energies lower than 12.5 eV; at higher energies, the DOUS maxima are shifted by 1.5–2 eV. The energy positions of the maxima of the total current spectra of the DPP–DCA and DPP films are changed only slightly as various substrates are used: highly ordered pyrolitic graphite (HOPG) and a CdS deposited layer-by-layer. The relative intensities of the maxima are different as various substrates are used. The characteristic shifts of the maxima of the total current spectra of the DPP–DCA films are approximately 1 eV at energies lower 12.5 eV above the Fermi level and 1.5–2 eV at higher energies, as compared to the positions of the corresponding maxima of the DPP films. | Density of Vacant Electronic States of Semiconductor Films of Molecules of Naphthalene and Diphenylphthalide Modified by Electroactive Functional Groups | 10.1134/S1063783420070100 |
2020-07-01 | Pesticide residues are detected in food items globally at levels that may cause health problems. Paper-based analytical devices have emerged as an alternative low-cost and field-based tools for determining target analytes including the pesticide residues. However, the paper devices with colorimetric detection system are limited by lower sensitivity due to their inability to record wavelength specific signal from the assays when image analysis detection method is used. In this paper, we report a low-cost analytical method that combines paper-analytical platform with a do-it-yourself desktop spectrometer to determine pesticide residues in vegetables and fruits. The pesticide determination method utilizes acetylcholinesterase enzyme inhibition assay on paper platform for signal generation. The signal of the assay was then measured using a spectrometer made from locally available components. The enzyme reaction parameters were optimized using multivariate optimization methodology to obtain better assay signal. The average repeatability of the assay method was 5.7% RSD. The combined method responded to the concentration of dichlorvos pesticide with a linear range from 0.01 to 0.25 mg/kg and detection limit of 0.023 mg/kg using only 4 μL of reagents and sample. As the enzyme inhibition assay used in this work is not able to discriminate individual pesticides, it can be used as a low-cost method for initial screening of pesticide residues in food samples in field settings. | A Combined System of Paper Device and Portable Spectrometer for the Detection of Pesticide Residues | 10.1007/s12161-020-01770-y |
2020-07-01 | The literature shows associations between maternal exposures to PM 2.5 and adverse pregnancy outcomes. There are few data from Latin America. We have examined PM 2.5 and pregnancy outcomes in Lima. The study included 123,034 births from 2012 to 2016, at three public hospitals. We used estimated daily PM 2.5 from a newly created model developed using ground measurements, satellite data, and a chemical transport model. Exposure was assigned based on district of residence ( n = 39). Linear and logistic regression analyzes were used to estimate the associations between air pollution exposure and pregnancy outcomes. Increased exposure to PM 2.5 during the entire pregnancy and in the first trimester was inversely associated with birth weight. We found a decrease of 8.13 g (−14.0; −1.84) overall and 18.6 g (−24.4, −12.8) in the first trimester, for an interquartile range (IQR) increase (9.2 µg/m 3 ) in PM 2.5 . PM 2.5 exposure was positively associated with low birth weight at term (TLBW) during entire pregnancy (OR: 1.11; 95% CI: 1.03–1.20), and at the first (OR: 1.11; 95% CI: 1.03–1.20), second (OR: 1.09; 95% CI: 1.01–1.17), and third trimester (OR: 1.10; 95% CI: 1.02–1.18) per IQR (9.2 µg/m 3 ) increase. Higher exposure to PM 2.5 was also associated with increased risk of small for gestational age (SGA). There were no statistically significant associations between PM 2.5 exposure and preterm births (PTB). Exposure to higher concentrations of PM 2.5 in Lima may decrease birth weight and increase the frequency of TLBW and SGA. Our study was inconsistent with the literature in finding no associations with preterm birth. | Association between maternal exposure to particulate matter (PM2.5) and adverse pregnancy outcomes in Lima, Peru | 10.1038/s41370-020-0223-5 |
2020-07-01 | The thioredoxin (Trx) system is an important enzyme family that regulates cellular redox homeostasis. Protein expression of Trx system family members has been assessed in various cancers and linked to various clinicopathological variables, disease progression, treatment response and survival outcomes but information is lacking in brain tumours. Expression of the system was therefore examined, by immunohistochemistry in different brain tumour types, adult and paediatric cases, to determine if expression was of importance to clinical outcome. Trx system proteins were expressed, to variable levels, across all brain tumour types with significant variations in expression between different tumour types/grades/regions. High Trx reductase (TrxR) expression was linked to worse prognosis across all cohorts. High cytoplasmic TrxR expression was significantly associated with adverse overall survival (OS) in adult glioblastoma ( P = 0.027) and paediatric low-grade glioma (LGG) patients ( P = 0.012). High expression of nuclear TrxR, cytoplasmic and nuclear Trx and Trx-interacting protein (TxNIP) was associated with improved OS in paediatric LGGs ( P = 0.031, P < 0.001, P = 0.044 and P = 0.018, respectively). For patients with high-grade gliomas, both high cytoplasmic TrxR and Trx expression were associated with poor OS ( P = 0.002 and P = 0.007, respectively). In medulloblastoma, high expression of cytoplasmic TrxR and Trx and nuclear Trx was associated with worse prognosis ( P = 0.013, P = 0.033 and P = 0.007, respectively); with cytoplasmic TrxR and nuclear Trx remaining so in multivariate analysis ( P = 0.009 and P = 0.013, respectively). The consistent finding that high levels of cytoplasmic TrxR are associated with a worse prognosis across all cohorts suggests that TrxR is an important therapeutic target in brain cancers. | Thioredoxin System Protein Expression Is Associated with Poor Clinical Outcome in Adult and Paediatric Gliomas and Medulloblastomas | 10.1007/s12035-020-01928-z |
2020-07-01 | The use of low embankments is of significant concern for ecological protection in arid-oasis areas. Based on the project of Sansha Expressway located in Kashgar City, Xinjiang, China, physical model tests were conducted in this study to investigate the dynamic response of the low embankment as per the effects of road structure, load amplitude, load frequency, load cycle, and moisture content. The dynamic stress is shown to increase with load amplitude while the dynamic elastic modulus decreases with load amplitude under short-term loading. The load frequency slightly influences the soil’s dynamic behavior; higher frequencies can improve the dynamic elastic modulus of the subgrade soil. The moisture content has greater influence on the mechanical properties of the subsoil than that of subgrade layer. The subgrade bears the majority of the traffic load as the stress dissipates to 37% of the whole value on its surface. The number of load cycles has the greatest effect on the dynamic response among the influencing factors tested. The dynamic elastic modulus with the type of long-term dynamic loading is only 40%–52% of that with static loading across the entire depth range. The dynamic stress shows significant accumulation with load cycles over the long-term dynamic loading test and becomes stable after 8 × 10 4 cycles of loading. An equation is established to quantify the cumulative dynamic stress in the low embankment under long-term dynamic loading conditions. | Low embankment dynamic response under vehicle traffic loads in arid-oasis areas | 10.1007/s11629-020-5980-z |
2020-07-01 | Due to the decline of formation pressure in the middle and late periods of low permeability reservoir development, the development effect deteriorates. Therefore, it is essential to restore and maintain reasonable formation pressure. Based on the two-phase fractional flow equation in low permeability porous media, we consider the flow characteristics in reservoirs with threshold pressure gradient and the influence of formation pressure on oil viscosity. By applying the material balance equation, we deduce the theoretical formula of future cumulative oil production with different formation pressures. In view of the contradictory relationship between cumulative oil production and water cut increasing rate, and we construct a bi-objective function to evaluate the reasonable formation pressure. Results show that during transition process from current formation pressure to reasonable formation pressure, when the reservoir formation pressure maintenance degree is 0.88, it can ensure that future cumulative oil production is relatively large and water cut increasing rate is relatively low. Under the condition of the same formation pressure maintenance degree, as threshold pressure gradient grows, the impact on cumulative oil production gradually increases. In order to provide a good development result, the formation pressure should be recovered as early as possible before it drops significantly. This method can be used to calculate reasonable formation pressure quantitatively and provide a reference for high efficiency development in low permeability reservoirs. | Reasonable Degree of Formation Pressure Maintenance in Low Permeability Reservoirs | 10.1007/s10553-020-01160-4 |
2020-07-01 | Biological effects of high fluence low-power (HFLP) lasers have been reported for some time, yet the molecular mechanisms procuring cellular responses remain obscure. A better understanding of the effects of HFLP lasers on living cells will be instrumental for the development of new experimental and therapeutic strategies. Therefore, we investigated sub-cellular mechanisms involved in the laser interaction with human hepatic cell lines. We show that mitochondria serve as sub-cellular “sensor” and “effector” of laser light non-specific interactions with cells. We demonstrated that despite blue and red laser irradiation results in similar apoptotic death, cellular signaling and kinetic of biochemical responses are distinct. Based on our data, we concluded that blue laser irradiation inhibited cytochrome c oxidase activity in electron transport chain of mitochondria. Contrary, red laser triggered cytochrome c oxidase excessive activation. Moreover, we showed that Bcl-2 protein inhibited laser-induced toxicity by stabilizing mitochondria membrane potential. Thus, cells that either overexpress or have elevated levels of Bcl-2 are protected from laser-induced cytotoxicity. Our findings reveal the mechanism how HFLP laser irradiation interfere with cell homeostasis and underscore that such laser irradiation permits remote control of mitochondrial function in the absence of chemical or biological agents. | Light-induced modulation of the mitochondrial respiratory chain activity: possibilities and limitations | 10.1007/s00018-019-03321-z |
2020-07-01 | Background Translational data analytics aims to apply data analytics principles and techniques to bring about broader societal or human impact. Translational data analytics for environmental health is an emerging discipline and the objective of this study is to describe a real-world example of this emerging discipline. Methods We implemented a citizen-science project at a local high school. Multiple cohorts of citizen scientists, who were students, fabricated and deployed low-cost air quality sensors. A cloud-computing solution provided real-time air quality data for risk screening purposes, data analytics and curricular activities. Results The citizen-science project engaged with 14 high school students over a four-year period that is continuing to this day. The project led to the development of a website that displayed sensor-based measurements in local neighborhoods and a GitHub-like repository for open source code and instructions. Preliminary results showed a reasonable comparison between sensor-based and EPA land-based federal reference monitor data for CO and NOx. Conclusions Initial sensor-based data collection efforts showed reasonable agreement with land-based federal reference monitors but more work needs to be done to validate these results. Lessons learned were: 1) the need for sustained funding because citizen science-based project timelines are a function of community needs/capacity and building interdisciplinary rapport in academic settings and 2) the need for a dedicated staff to manage academic-community relationships. | Translational data analytics in exposure science and environmental health: a citizen science approach with high school students | 10.1186/s12940-020-00627-5 |
2020-07-01 | Flow past four side-by-side identical square cylinders arranged normal to the flow have been found to show interesting and important flow features which are very difficult to get through experiments. Lattice Boltzmann method (LBM) is used for numerical simulations of two-dimensional (2D) flow around four side-by-side arranged cylinders. In this study, the Reynolds number (Re) is chosen to be 60, 80, 100, 120 and 140 and the spacing ratio g * (= g / D , where D is the size of cylinder and g is the distance between the cylinders) is set at 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5 and 4. Based on the flow characteristics, seven distinct and unique flow regimes are identified for different ranges of Re and g *. Physical features of each flow regime such as wake structures, vortex dynamics, gap flow behavior, time histories of lift coefficients, shedding frequencies and hydrodynamic forces are thoroughly discussed. The Reynolds numbers strongly affect the flow, especially at 0 ≤ g * ≤ 2, in terms of vortex-shedding frequency. A significant secondary frequency is also found other than the primary frequency in the base-bleed and flip-flopping flow regimes. It is observed that for g * ≥ 2.5 primary shedding frequency strongly affects the flow dynamics and the mutual interaction of the wakes behind the cylinders decreases with an increase in the Reynolds number. The Strouhal value is same for the outer and inner cylinders in inphase–antiphase weak interaction flow regime and different for base-bleed and flip-flopping flow regimes. In inphase asynchronous weak interaction flow regime, the Strouhal number is same for all four cylinders. | Fluid Dynamics of Flow Around Side-by-Side Arranged Cylinders | 10.1007/s13369-020-04603-6 |
2020-07-01 | The content of damaged 8-hydroxy-2-deoxyguanosine nitrogenous bases in the blood DNA of healthy donors and patients with epidermolysis bullosa after exposure to an alternating magnetic field of 550 ± 30 A/m in the frequency range from 3 to 60 Hz in vitro was determined using an enzyme immunoassay. The degree of oxidative DNA damage in epidermolysis bullosa was almost twice as high as in healthy donors. It was shown that there was a significant increase in the level of 8-oxoguanine in the DNA of both groups after the magnetic field treatment, which depended in a complex way on the frequency. The resulting effect is explained by the generation of reactive oxygen species under the influence of a magnetic field and the disruption of DNA repair processes. | Oxidative Damage to DNA under the Action of an Alternating Magnetic Field | 10.1134/S0006350920040247 |
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