69 research outputs found
High temperature superconductivity of quaternary hydrides XM3Be4H32 (X, M = Ca, Sr, Ba, Y, La, Ac, Th) under moderate pressure
The compressed hydrogen-rich compounds have received extensive attention as
promising candidates for room temperature superconductivity, however, the high
pressure required to stabilize such materials hinders their wide practical
application. In order to search for potential superconducting hydrides that are
stable at low pressures, we have investigated the crystal structures and
properties of quaternary hydrides, XM3Be4H32 (X, M = Ca, Sr, Ba, Y, La, Ac, Th)
based on the first-principles calculations. We identified nine dynamically
stable compounds at moderate pressure of 20 GPa. Strikingly, their
superconducting transition temperatures are much higher than that of liquid
nitrogen, especially CaTh3Be4H32 (124 K at 5 GPa), ThLa3Be4H32(134 K at 10
GPa), LaAc3Be4H32 (135 K at 20 GPa) and AcLa3Be4H32 (153 K at 20 GPa) exhibit
outstanding superconductivity at mild pressures. Metal atoms acting as
pre-compressors donate abundant electrons to hydrogen, weakening the H-H
covalent bond and thus facilitating the metallization of the hydrogen
sublattice. At the same time, the appropriate combination of metal elements
with different ionic radius and electronegativity can effectively tune the
electronic structure near the Fermi level and improve the superconductivity.
These findings fully reveal the great promise of hosting high-temperature
superconductivity of quaternary hydrides at moderate pressures and will further
promote related exploration.Comment: 14 pages, 6 figure
High fat diet significantly changed the global gene expression profile involved in hepatic drug metabolism and pharmacokinetic system in mice.
Background: High fat diet impact transcription of hepatic genes responsible for drug metabolism and pharmacokinetics. Until now, researches just focused on a couple specific genes without a global profile showing. Age-dependent manner was also not noted well. This study aims to investigate the high fat diet effect on transcriptome of drug metabolism and pharmacokinetic system in mouse livers and show the age-dependent evidence.
Methods: C57BL/6 male mice were used in this experiment. High fat diet was used to treat mice for 16 and 38 weeks. Serum total cholesterol, low density lipoprotein cholesterol, aspartate transaminase, and alanine transaminaselevels were measured. Meanwhile, Histology, RNA-Seq, RT-PCR analysis and fourteen major hepatic bile acids quantification were performed for the liver tissues. Data was mined at levels of genes, drug metabolism and pharmacokinetic sysem, and genome wide.
Results: Treatment with high fat diet for 38 weeks significantly increased levels of serum lipids as well as aspartate transaminase, and alanine transaminase. Meanwhile, lipid accumulation in livers was observed. At week 38 of the experiment, the profile of 612 genes involved in drug metabolism and pharmacokinetics was significantly changed, indicated by a heatmap visulization and a principal component analysis. In total 210 genes were significantly regulated. Cyp3a11, Cyp4a10, and Cyp4a14 were down-regulated by 10-35 folds, while these three genes also were highly expressed in the liver. High fat diet regulated 11% of genome-wide gene while 30% of genes involved in the hepatic drug metabolism and pharmacokinetic system. Genes, including
Conclusions: High fat diet changed the global transcription profile of hepatic drug metabolism and pharmacokinetic system with a age-dependent manner
Gypenosides Altered Hepatic Bile Acids Homeostasis in Mice Treated with High Fat Diet
Abstract
Gypenosides extracted from Gynostemma pentaphyllum (Thunb.) Makino have significant role in reducing serum lipid level and treating fatty liver diseases, however, without clear mechanism. As gypenosides share the similar core structures with bile acids (the endogenous ligands of nuclear receptor FXR), we hypothesize that gypenosides may improve hypercholesterolemia via FXR-mediated bile acids signaling. The present study was designed to validate the role of gypenosides in reducing levels of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), as well as in regulating bile acids homeostasis and related gene expression levels. The C57BL/6 male mice were divided into four groups. Mice in groups ND and HFD were fed with normal diet and high fat diet for 38 weeks, respectively. In groups HFD+GP and HFD+ST, mice were fed with high fat diet for 38 weeks and treated with gypenosides and simvastatin (positive control) from weeks 16 to 38, respectively. Serum TC and LDL-C levels were assayed by commercially available kits. Expression levels of genes were tested by the quantitative real-time PCR. The LC-MS/MS was applied to quantify major bile acids in mice livers. Our results showed that gypenosides significantly decreased serum TC and LDL-C levels. The gene expression level of Shp was downregulated while the levels of Cyp7a1, Cyp8b1, Fxr, Lrh1, Jnk1/2, and Erk1/2were upregulated by gypenosides. Indicated by LC-MS/MS technology, gypenosides increased the hepatic levels of several free bile acids and most taurine-conjugated bile acids while decreasing glycine-conjugated bile acids levels. In addition, gypenosides decreased the CA/CDCA ratio. Gypenosides may improve the abnormal lipid profile of HFD-fed mice via two pathways: (1) enhancing the bile acids biosynthesis from cholesterol; (2) decreasing the CA/CDCA ratio which is positively related to cholesterol absorption
Textile Robotic Interaction for Designer-Robot Collaboration
This late-breaking report describes lab-based robot experiments involving two robot arms scanning and interaction with a set of 12 novel sustainable materials programmed with handfeel gestures inspired by how designers evaluate textile materials. The aim of gathering this data is to spur research in robot perception of soft materials and to contribute towards human-robot collaborative design systems. The complete dataset including scanned images, video of interactions accompanied by the code to produce robot motion paths are made publically available
Protection effect of gut microbiota composition and acetate absorption against hypertension-induced damages on the longevity population in Guangxi, China
IntroductionRecent evidence supports a role for the gut microbe-metabolites in longevity. However, the phenomenon of hypertension is more common in the longevity area and whether hypertension is associated with longevity remains unclear. Here, we hypothesize that the levels of gut microbiota, SCFAs, and urine metabolites were different between hypertension elderly and hypertension longevity.MethodsWe recruited 46 elderly volunteers from Donglan County, Guangxi, and 32 were selected and included in the experiment. The subjects with hypertension were divided into two groups according to age, Hypertension Elderly (HTE, aged 70.5 ± 8.59, n = 19) and Hypertension Longevity (HTL, aged 100 ± 5.72, n = 13). The gut microbiota, SCFAs, and urine metabolites were determined by three-generation 16S rRNA full-length sequencing, GC-MS, and 1H-NMR, respectively.ResultsCompared with the HTL group, the HTE group had higher levels of hypertension-related genera Klebsiella and Streptococcus, while having lower levels of the SCFA-producing genera Bacteroides, Faecalibacterium, and Alistipes. Based on LEFse analysis, Klebsiella pneumoniae, Lactobacillus gasseri, Streptococcus salivarius, Ruminococcus, Actinomyces, Rikenellaceae, f_Saccharimonadaceae, Clostridium perfringens, and Bacteroids, Faecalibacterium prausnitzii, Parabacteroides, Alistipes were biomarkers that showed significant differences between the groups. In addition, the microbial pathways associated with K. pneumoniae and E. coli may promote hypertension, while A. muciniphila may play a role in reversing the development of hypertension in long-lived elderly. Metabolomics revealed that HTL contained a lower concentration of fecal acetate and propionate than HTE, while it contained a higher concentration of serum acetate and urine acetate. Furthermore, their immune cells exhibited no significant changes in SCFAs receptors.ConclusionAlthough long-lived elderly have extremely high systolic blood pressure, their unique gut microbiota composition and efficient acetate absorption in the colon may offset the damages caused by hypertension and maintain healthy homeostasis
Ensuring water resource security in China; the need for advances in evidence based policy to support sustainable management.
China currently faces a water resource sustainability problem which is likely to worsen into the future. The Chinese government is attempting to address this problem through legislative action, but faces severe challenges in delivering its high ambitions. The key challenges revolve around the need to balance water availability with the need to feed a growing population under a changing climate and its ambitions for increased economic development. This is further complicated by the complex and multi-layered government departments, often with overlapping jurisdictions, which are not always aligned in their policy implementation and delivery mechanisms. There remain opportunities for China to make further progress and this paper reports on the outcomes of a science-to-policy roundtable meeting involving scientists and policy-makers in China. It identifies, in an holistic manner, new opportunities for additional considerations for policy implementation, continued and new research requirements to ensure evidence-based policies are designed and implemented and identifies the needs and opportunities to effectively monitor their effectiveness. Other countries around the world can benefit from assessing this case study in China
Analysis of Debonding Failures of the Screen and Case during Tablet Drop
In recent years, due to the increasingly powerful functions of tablets, more and more people have used tablets. The failure of the screen caused by debonding failure between the screen and the case of the tablet due to drops will affect the normal use of the tablet. However, there have been few studies on the debonding methods of the screen and the case of the tablet, as well as the factors influencing the debonding between the screen and the case of the tablet. Numerical analysis software was used in this paper to simulate the iPad Air (Air) drop process, and the cohesive zone model and tiebreak contact were used to simulate the debonding process between the screen and case of the Air tablet, respectively. When the results are compared to the experiments, the results show that the cohesive zone model is superior. The effects of various rounded corner radii, drop postures in the XY plane, materials of the outer case, and strain rates of PC/ABS on the localized debonding between the outer case and outer glass of the Air during the drop process were investigated. The degree of debonding between the Air model’s outer case and outer glass is defined by t, which is the ratio of the area of the deleted cohesive elements to the total area of the cohesive elements. The results show that the rounded corner radius and the strain rate of PC/ABS have less influence on t; the t of the Air model dropped at 45° in the XY plane is 37.7% of that dropped at 0° and 90°; and the t of the Air model with glass as the outer case material is 48% of that with aluminum alloy as the outer case material. These studies serve as a foundation for tablet design and material selection
Numerical Analysis of the Wing Leading Edge Electro-Impulse De-Icing Process Based on Cohesive Zone Model
Aircraft icing has historically been a critical cause of airplane crashes. The electro-impulse de-icing system has a wide range of applications in aircraft de-icing due to its lightweight design, low energy consumption, high efficiency, and other advantages. However, there has been little study into accurate wing electric-impulse de-icing simulation methods and the parameters impacting de-icing efficacy. Based on the damage mechanics principle and considering the influence mechanisms of interface debonding and ice fracture on ice shedding, this paper establishes a more accurate numerical model of wing electric-impulse de-icing using the Cohesive Zone Model (CZM). It simulates the process of electric-impulse de-icing at the leading edge of the NACA 0012 wing. The numerical results are compared to the experimental results, revealing that the constructed wing electro-impulse de-icing numerical model is superior. Lastly, the effects of varying ice–skin interface shear adhesion strengths, doubler loading positions, and impulse sequences on de-icing effectiveness were studied. The de-icing rate is a quantitative description of the electro-impulse’s de-icing action, defined in the numerical model as the ratio of cohesive element deletions to the total elements at the ice–skin interface. The findings reveal that varying shear adhesion strengths at the ice–skin interface significantly impact the de-icing effect. The de-icing rate steadily falls with increasing shear adhesion strength, from 66% to 56%. When two, four, and seven impulses were applied to doubler two, the de-icing rates were 59%, 71%, and 71%, respectively, significantly increasing the de-icing efficiency compared to when impulses were applied to doubler one. Doubler one and two impulse responses are overlaid differently depending on the impulse sequences, resulting in varying de-icing rates. When the impulse sequence is 20 ms, the superposition results are optimal, and the de-icing rate reaches 100%. These studies can guide the development and implementation of a wing electric-impulse de-icing system
Simulation of Mouldboard Plough Soil Cutting Based on Smooth Particle Hydrodynamics Method and FEM–SPH Coupling Method
In the field of agricultural machinery, various empirical field tests are performed to measure the tillage force for precision tillage. However, the field test performance is costly and time-consuming, and there are many constraints on weather and field soil conditions; the utilization of simulation studies is required to overcome these shortcomings. As a result, the SPH method and the coupled FEM-SPH method are used in this paper to investigate the mouldboard plough–soil interaction. In this paper, the finite element software LS-DYNA was used to build the SPH model and the FEM-SPH coupling model of soil cutting, as well as to investigate the change in cutting resistance during the soil cutting process. The simulation results are compared with those of the experiments, and the curves of the simulation and experiment are in good agreement, which verifies the reliability of the model. The validated simulation model was used to investigate the effects of the cutting speed, depth of cut, inclination angle, and lifting angle of the mouldboard plough on cutting resistance. The simulation studies show that the SPH model takes 5 h and 2 min to compute, while the FEM-SPH coupled model takes 38 min; obviously, the computational efficiency of the FEM-SPH coupled model is higher. The relative errors between the SPH model and the experiment are 2.17% and 3.65%, respectively. The relative errors between the FEM-SPH coupled model and the experiment are 5.96% and 10.67%, respectively. Obviously, the SPH model has a higher computational accuracy. The average cutting resistances predicted by the SPH model and the FEM-SPH coupled model, respectively, were 349.48 N and 306.25 N; these resistances are useful for precision tillage. The cutting resistance increases with the increase in cutting speed and is quadratic; the cutting resistance increases with the increase in cutting depth and is quadratic; the horizontal cutting resistance and the combined cutting resistance increase with the increase in inclination angle, while the vertical cutting resistance remains essentially constant with the increase in inclination angle; the horizontal cutting resistance and combined cutting resistance increase as the lifting angle increases, while the vertical cutting resistance decreases as the lifting angle increases
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