纤维型黏土在日化领域的应用研究进展

纤维型黏土(包含海泡石与坡缕石/凹凸棒石)是一类晶体结构呈纤维状、含水富镁铝硅酸盐的天然一维黏土矿物,其特殊的微观形貌(棒状、纤维状或纤维集合体)和纳米级孔道赋予了这类黏土矿物优异的离子交换能力、吸附性能、流变调节性和载体功能。近年来,纤维型黏土在个人护理品、洗涤用品等日用消费品中的应用增长迅速。该文以纤维型黏土的流变调节、防晒修饰、抑菌消炎、吸附与控释四种应用特性为主线,综述了这类天然黏土矿物在日用化学工业领域的应用特性、相关机理及毒理学研究进展,分析了纤维型黏土在日化领域应用面临的问题与挑战,并对其未来的发展趋势进行了展望,为我国科研人员充分利用优势矿物资源,进一步开发出高技术含量的日化产品提供参考。

Optimum Tilt Angle of Flow Guide in Steam Turbine Exhaust Hood Considering the Effect of Last Stage Flow Field

Abstract Heat transfer and vacuum in condenser are influenced by the aerodynamic performance of steam tur- bine exhaust hood. The current research on exhaust hood is mainly focused on analyzing flow loss and optimal design of its structure without consideration of the wet steam condensing flow and the exhaust hood coupled with the front and rear parts. To better understand the aerodynamic performance influenced by the tilt angle of flow guide inside a diffuser, taking a 600 MW steam turbine as an example, a numerical simulator CFX is adopted to solve compressible three-dimensional （3D） Reynolds time-aver- aged N-S equations and standard k-e turbulence model. And the exhaust hood flow field influenced by different tilt angles of flow guide is investigated with consideration of the wet steam condensing flow and the exhaust hood coupled with the last stage blades and the condenser throat. The result shows that the total pressure loss coefficient and the static pressure recovery coefficient of exhaust hood change regularly and monotonously with the gradual increase of tilt angle of flow guide. When the tilt angle of flow guide is within the range of 30~ to 40~, the static pressure recovery coefficient is in the range of 15.27% to 17.03% and the total pressure loss coefficient drops to approximately 51%, the aerodynamic performance of exhaust hood is significantly improved. And the effectiveenthalpy drop in steam turbine increases by 0.228% to 0.274%. It is feasible to obtain a reasonable title angle of flow guide by the method of coupling the last stage and the condenser throat to exhaust hood in combination of the wet steam model, which provides a practical guidance to flow guide transformation and optimal design in exhaust hood.

Manipulation and optimization of electron transport by nanopore array targets

The transport of sub-picosecond laser-driven fast electrons in nanopore array targets is studied.Attributed to the generation of micro-structured magnetic fields,most fast electron beams are proven to be effectively guided and restricted during the propagation.Different transport patterns of fast electrons in the targets are observed in experiments and reproduced by particle-in-cell simulations,representing two components:initially collimated low-energy electrons in the center and high-energy scattering electrons turning into surrounding annular beams.The critical energy for confined electrons is deduced theoretically.The electron guidance and confinement by the nano-structured targets offer a technological approach to manipulate and optimize the fast electron transport by properly modulating pulse parameters and target design,showing great potential in many applications including ion acceleration,microfocus x-ray sources and inertial confinement fusion.

Labyrinth Seal Design Optimization Based on Quadratic Regression Orthogonal Experiment

The influence of labyrinth seal structure parameters and their interaction on the characteristics of leakage amount are numerically investigated by conducting a quadratic regression orthogonal experiment. To determine the optimal structure parameters of the steam seal for minimizing the leakage amount, a reliable regression equation that does not lack of fit is established. The flow characteristics of the fluid in the labyrinth seal are analyzed in detail. Results show that the leakage amount is greatly influenced by seal cavity depth, convex platform height, seal tooth thickness, and tooth tip clearance, with the tip clearance having the most significant effect. The interaction among the four items exerts a certain impact on the leakage amount. The proposed regression equation exhibits a good significance and does not lack of fit. After optimization, the labyrinth seal demonstrates increased entropy and energy dissipation at the tip of the seal tooth, as well as decreased speed and inertia effect in the cavity, suggesting that the resistance leakage performance of the optimized labyrinth seal is improved.

Ginkgo paste improves tinea corporis in a guinea pig model

To investigate the effects of Ginkgo paste for external use on tinea corporis in a guinea pig model.The guinea pig tinea corporis model were induced by infection with Trichophyton mentagrophytes strains.And then,high and low doses of Ginkgo water-paste and alcohol-paste were administrated to the animals.The symptom,tinea corporis skin lesions and histopathological aspects of guinea pig were analyzed.High and low doses of Ginkgo alcohol-paste and Ginkgo water-paste could significantly reduced the tinea corporis symptom(P<0.01),increased negative rate of strain culture(P<0.01),and improved pathological changes of tinea corporis(P<0.01).The best efficacy was observed in high dose ginkgo alcohol paste group.These results suggest that Ginkgo paste exhibits the efficacy to treat tinea corporis in a guinea pig model.

The effects of incident light wavelength difference on the collective stimulated Brillouin scattering in plasmas

The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility.Although each beam intensity is below its individual threshold for stimulated Brillouin backscattering(SBS),collective behaviors are excited to enhance the octad SBS.In particular,when two-color/cone lasers with wavelength separation 0.3 nm are used,the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain.This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation.This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.

Collective stimulated Brillouin scattering modes of two crossing laser beams with shared scattered wave

In inertial confinement fusion(ICF),overlapping of laser beams is common.Owing to the effective high laser intensity of the overlapped beams,the collective mode of stimulated Brillouin scattering(SBS)with a shared scattered light wave is potentially important.In this work,an exact analytic solution for the convective gain coefficient of the collective SBS modes with shared scattered wave is presented for two overlapped beams based on a linear kineticmodel.The effects of the crossing angle,polarization states,and finite beamoverlapping volume of the two laser beams on the shared light modes are analyzed for cases with zero and nonzero wavelength difference between the two beams.It is found that all these factors have a significant influence on the shared lightmodes of SBS.Furthermore,the out-of-plane modes,in which the wavevectors of daughter waves lie in different planes from the two overlapped beams,are found to be important for certain polarization states and especially for obtuse crossing angles.In particular,adjusting the polarization directions of the two beams to be orthogonal to each other or tuning the wavelength difference to a sufficiently large value(of the order of nanometers)are found to be effective methods to suppress the shared light modes of SBS.This work will be helpful for comprehending and suppressing collective SBS with shared scattered waves in ICF experiments.

热电耦合作用下功率器件引脚开裂的机理

在电子产品的小型化的趋势下,电力电子器件所承受的工作温度、电流密度越来越高,这给封装材料提出了严峻的挑战.一种引线框架材料为C194合金的MOSFET器件,在高电流密度的工作环境下服役3~4年后发生了引脚开裂的现象.针对该失效现象,使用扫描电子显微镜对界面金属间化合物和断口形貌进行了精细的微观表征,确定了电迁移和热迁移的耦合作用是导致引脚开裂的主要原因.具体地,对于器件源极来说,Cu原子的电迁移与热迁移方向相反,且热迁移扩散通量较大,抵消了电迁移的作用从而导致了阳极开裂的反常现象.对于器件漏极来说,Cu原子的热迁移方向与电迁移方向相同,热迁移加速了阴极界面裂纹的萌生与扩展,开裂情况最为严重.为了进一步揭示开裂机理,我们使用电子探针、透射电子显微镜分析发现,在C194合金与金属间化合物界面上,原本弥散分布于C194合金内部的铁晶粒发生了明显的晶粒长大,并富集形成连续层.由于细小铁晶粒组成的富铁层弱化原有的界面结合力,成为薄弱环节.因此,在外加热应力或机械应力下,裂纹总是沿着由铁晶粒形成的富铁层发生开裂.综上,该器件引脚开裂的失效模式为典型的多场耦合作用下的失效形式,相关机理将为产品工艺优化和提高使用寿命提供理论指导.

Liver Stiffness Measurement Can Reflect the Active Liver Necroinflammation in Population with Chronic Liver Disease:A Real-world Evidence Study

Background and Aims: Non-invasive evaluation of liver nec-roinflammation in patients with chronic liver disease is an un-met need in clinical practice.The diagnostic accuracy of transient elastography-based liver stiffness measurement(LSM)for liver fibrosis could be affected by liver necroinflam-mation,the latter of which could intensify stiffness of the liver.Such results have prompted us to explore the diagnosis potential of LSM for liver inflammation.Methods: Three cross-sectional cohorts of liver biopsy-proven chronic liver dis-ease patients were enrolled,including 1417 chronic hepatitis B(CHB)patients from 10 different medical centers,106 non-al-coholic steatohepatitis patients,and 143 patients with auto-immune-related liver diseases.Another longitudinal cohort of 14 entecavir treatment patients was also included.The re-ceiver operating characteristic(ROC)curve was employed to explore the diagnostic value of LSM.Results: In CHB patients,LSM value ascended with the increased severity of liver nec-roinflammation in patients with the same fibrosis stage.Such positive correlation between LSM and liver necroinflammation was also found in non-alcoholic steatohepatitis and autoim-mune-related liver diseases populations.Furthermore,the ROC curve exhibited that LSM could identify moderate and se-vere inflammation in CHB patients(area under the ROC curve as 0.779 and 0.838)and in non-alcoholic steatohepatitis pa-tients(area under the ROC curve as 0.826 and 0.871),respec-tively.Such moderate diagnostic value was also found in autoimmune-related liver diseases patients.In addition,in the longitudinal entecavir treated CHB cohort,a decline of LSM values was observed in parallel with the control of inflam-matory activity in liver.Conclusions: Our study implicates a diagnostic potential of LSM to evaluate the severity of liver necroinflammation in chronic liver disease patients.

Characterization of natural fiber from manau rattan(Calamus manan)as a potential reinforcement for polymer-based composites

Researches on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications.Herein,in this study,novel cellulosic fibers were extracted from the stem of manau rattan(Calamus manan)by mechanical separation.The chemical,thermal,mechanical and morphological properties of manau rattan fibers were comprehensively analyzed and studied by Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)analysis,thermogravimetric analysis(TGA),single fiber tensile test and scanning electron microscopy(SEM).Component analysis re-sults showed that the cellulose,hemicellulose and lignin contents of C.manan fibers were 42wt%,20wt%,and 27wt%,respectively.The surface of the rattan fiber was hydrophilic according to the oxygen/carbon ratio of 0.49.The C.manan has a crystalline index of 48.28%,inducing a max-imum degradation temperature of 332.8°C.This reveals that it can be used as a reinforcement for thermoplastic composites whose operating temperature is below 300°C.The average ten-sile strength can reach(273.28±52.88)MPa,which is beneficial to improve the mechanical properties of rattan fiber reinforced composites.The SEM images displayed the rough surface of the fiber,which helped to enhance the interfacial adhesion between the fibers and matrices in composites.These results indicate the great potential of C.manan fibers as the reinforcement in polymer-based composites.

Variations in EXD3 caused congenital cataracts in three Chinese families

Congenital cataract is a clinically and genetically heterogeneous disease characterized by any opacity of the lens presenting at birth or in the first year of life,with an incidence of 1–6/10,000 live births in developed countries and 5–15/10,000 live births in developing countries.Congenital cataract accounts for 7.4%–15.5%of all childhood blindness,and it occurs as either a syndromic disease or an isolated(nonsyndromic)disease with or without other ocular malformations,such as microcornea.