GaInX_3(X=S,Se,Te):Ultra-low thermal conductivity and excellent thermoelectric performance

Seeking intrinsically low thermal conductivity materials is a viable strategy in the pursuit of high-performance thermoelectric materials.Here,by using first-principles calculations and semiclassical Boltzmann transport theory,we systemically investigate the carrier transport and thermoelectric properties of monolayer Janus GaInX_(3)(X=S,Se,Te).It is found that the lattice thermal conductivities can reach values as low as 3.07 W·m^(-1)·K^(-1),1.16 W·m^(-1)·K^(-1)and 0.57 W·m^(-1)·K^(-1)for GaInS_(3),GaInSe_(3),and GaInTe_(3),respectively,at room temperature.This notably low thermal conductivity is attributed to strong acoustic-optical phonon coupling caused by the presence of low-frequency optical phonons in GaInX_(3) materials.Furthermore,by integrating the charac teristics of electronic and thermal transport,the dimensionless figure of merit ZT can reach maximum values of 0.95,2.37,and 3.00 for GaInS_(3),GaInSe_(3),and GaInTe_(3),respectively.Our results suggest that monolayer Janus GaInX_(3)(X=S,Se,Te)is a promising candidate for thermoelectric and heat management applications.

Tumor suppressor role of mi R-133a in gastric cancer by repressing IGF1R

AIM:To investigate the function and mechanism of mi R-133a in gastric cancer(GC)and its relationship with clinicopathological characteristics of GC.METHODS:A total of 105 GC patients who underwent surgical resection as primary treatment were selected for this study.Real-time quantitative reverse transcriptase polymerase chain(q RT-PCR)was used to examine the expression levels of mi R-133a in human GC and adjacent non-tumor tissues,as well as in GC cell lines(SGC-7901,BGC-823,MGC-803,and AGS)and a human gastric mucosal epithelial cell line(GES-1).The biological role of mi RNA(mi R)-133a was assessed in the GC cell lines using MTT,apoptosis,migration and invasion,and colony formation assays,and xenograft tumorigenesis.q RT-PCR and western blot analyses were used to evaluate the potential target gene expression of mi R-133a.Pearson’s correlation was calculated to evaluate the correlation between mi R-133a and insulinlike growth factor 1 receptor(IGF1R)expression.The regulation of IGF1R by mi R-133a was verified using the luciferase reporter assay.RESULTS:In 80%of the 105 GC patients,the mean expression of mi R-133a was significantly downregulated in tumor tissues compared with adjacent normal tissues(1.215±0.1477 vs 3.093±0.4104,P<0.0001).Downregulation of mi R-133a was significantly correlated with the degree of differentiation(P=0.01),local invasion(P=0.001)and TNM stage(P=0.02)in GC patients.Compared with a control construct,forced expression of mi R-133a in GC cell lines inhibited proliferation(0.4787±0.0219 vs 0.7050±0.0147,P=0.0013 in SGC-7901 cells;and 0.5448±0.0085vs 0.7270±0.0084,P=0.001 in MGC-803 cells);migration(0.6333±0.0233 vs 1.037±0.0584,P=0.003 in SGC-7901 cells;0.6126±0.0311 vs 1.024±0.0456,P=0.0017 in MGC-803 cells);and invasion(0.613±0.0399 vs 1.033±0.0278,P=0.0013 in SGC-7901 cells;0.7433±0.0221 vs 1.017±0.0311,P=0.002 in MGC-803 cells).It also induced apoptosis(18.19%±0.2483%vs 5.887%±0.3837%,P<0.0001 in SGC-7901 cells;22.69%±0.7846%vs9.347%±0.3012%,P<0.0001 in MGC-803 cells).Furthermore,mi R-133a inhibited tumor growth and xenograft tumorigenesis of SGC-7901 cells in vivo.In addition,we identified IGF1R as a regulatory target of mi R-133a in GC.CONCLUSION:This study suggests that mi R-133a is downregulated in GC and functions as a tumor suppressor in vitro and in vivo partly by repressing IGF1R.

Ankaflavin ameliorates steatotic liver ischemiareperfusion injury in mice

BACKGROUND： It is well-known that steatotic liver is more susceptible to ischemia-reperfusion （I/R） injury during liver transplantation, liver resection and other liver surgeries. The increasing incidence of non-alcoholic fatty liver disease （NAFLD） decreases the availability of liver donors. Although steatotic liver is now accepted as a source of liver for trans- plantation, NAFLD exacerbates the liver injury after liver surgery. The present study was to investigate the protective role of ankaflavin in steatotic liver I/R injury.

基于相似设计理论的自通风型牵引电机风扇降噪优化

本文详细论述了风扇相似设计理论在牵引电机风扇性能及噪声优化应用中的方法,依据某气动性能较好的参考风扇设计了适合自通风型牵引电机的低噪声新风扇来替换原有风扇。同时基于自通风型牵引电机的非定常流场仿真结果,建立有限元声学计算模型,仿真计算了该电机在最高转速下的气动噪声,获取了由电机风扇产生的气动噪声幅值与频谱特性。通过对安装原风扇与优化后风扇电机的气动噪声计算结果进行对比,表明安装相似理论设计风扇的电机在高转速时有非常明显的降噪效果,达到了优化设计的目的。同时表明风扇相似设计理论在自通风型牵引电机降噪设计中具有一定的应用前景与推广价值。

Investigation on UV-curing Reprocessable Thermosets Bearing Hindered Urea Bonds and Their Composites with Modified Zinc Oxide Nanoparticles

In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure.The prepolymers were characterized fully by various techniques.Then,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and compared.Different from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property.Furthermore,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their nanocomposites.The influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then decreased.The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample.In addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.

Reviewing and understanding the stability mechanism of halide perovskite solar cells

Finding sustainable and renewable energy to replace traditional fossil fuel is critical for reducing greenhouse gas emission and avoiding environment pollution.Solar cells that convert energy of sunlight into electricity offer a viable route for solving this issue.At present,halide perovskites are the most potential candidate materials for solar cell with considerable power conversion efficiency,whereas their stability remains a challenge.In this work,we summarize four different key factors that influence the stability of halide perovskites:(a)effect of environmental moisture on the degradation of halide perovskites.The performance of halide perovskite solar cells is reduced due to hydrated crystal hinders the diffusion of photo-generated carriers,which can be solved by materials encapsulation technique;(b)photoinduced instability.Through uncovering the underlying physical mechanism,we note that materials engineering or novel device structure can extend the working life of halide perovskites under continuous light exposure;(c)thermal stability.Halide perovskites are rapidly degraded into PbI2 and volatile substances as heating due to lower formation energy,whereas hybrid perovskite is little changed;(d)electric field effect in the degradation of halide perovskites.The electric field impacts significantly on the carrier separation,changes direction of photo-induced currents and generates switchable photovoltaic effect.For each key factor,we have shown in detail the underlying physical mechanisms and discussed the strategies to overcome this stability difficulty.We expect this review from both theoretical and experimental points of view can be beneficial for development of perovskite solar cell materials and promotes practical applications.

Excellent thermoelectric performance in weak-coupling molecular junctions with electrode doping and electrochemical gating

Excellent thermoelectric performance in molecular junctions requires a high power factor, a low thermal conductance, and a maximum figure of merit(ZT) near the Fermi level. In the present work, we used density functional theory in combination with a nonequilibrium Green’s function to investigate the thermoelectric performance of carbon chain-graphene junctions with both strong-coupling and weak-coupling contact between the electrodes and the molecules. The results revealed that a room temperature ZT of 4 could be obtained for the weak-coupling molecular junction, approximately one order of magnitude higher than that reached by the strong-coupling junction. The reason for this is that strong interfacial scattering suppresses most of the phonon modes in weak-coupling systems, resulting in ultralow phonon thermal conductance. The influence of electrode width,electrode doping, and electrochemical gating on the thermoelectric performance of the weak-coupling system was also investigated, and the results revealed that an excellent thermoelectric performance can be obtained near the Fermi level.