An experimental investigation on slope stability under drawdown conditions using transparent soils

This paper presents an experimental investigation into slope failure during water-level drawdown using transparent soil. The internal characteristics of slope failure are not well-known due to the limitations of the techniques used in the experiments conducted to date. In this study, transparent soil is used to visualize the process of slope failure. We developed a water-level control system to implement simulation of the drawdown of the water level at various speeds and used a charge-coupled device camera to capture images during the entire slope failure process. Particle image velocimetry was used to measure the displacement of the sand particles and identify the sliding zones. The flow paths of the fluid inside the slope were illuminated using an organic dye. The results show that the slope failure process can be divided into two stages: surface and overall sliding. The overall sliding of the slope is caused by the gradual development of partial instability, and the failure mode is a cyclic failure. The slope angle is different above and below the water level during the process of sliding. In our experiments, the slope angle is about 20° above the water level, which is the same as the final stable slope angle, and about 35° below the water level, which is the same as the initial slope angle. This means that the drawdown influences the angle above the water level but has little influence on the angle below the water level. The results of this paper provide a better understanding of the physical behavior and failure mode of soil slopes caused by drawdowns near the coast.     

Structural,optical and electrical properties of indium doped Cu2ZnSn(S,Se)4 thin films synthesized by the DC and RF reactive magnetron cosputtering

Element doping into the Cu₂ZnSn(S,Se)₄ (CZTSSe) absorber is an effective method to optimize the performance of thin film solar cells. In this study, the Cu₂In_xZn_1-xSn(S,Se)₄ (CIZTSSe) precursor film was deposited by magnetron cosputtering technique using indium (In) and quaternary Cu₂ZnSnS₄ (CZTS) as targets. Meanwhile, the In content was controlled using the direct current (DC) power on In target (P_In). A single kesterite CIZTSSe alloy was formed by successfully doping a small number of In³⁺ into the main lattice of CZTSSe. The partial Zn²⁺ cations were substituted by In³⁺ ions, resulting in improving properties of CZTSSe films. Morphological analysis showed that large grain CIZTSSe films could be obtained by doping In. The well-distributed, smooth, and dense film was obtained when the P_In was 30 W. The band gap of CIZTSSe could be continuously adjusted from 1.27 to 1.05 eV as P_In increased from 0 to 40 W. In addition, the CIZTSSe alloy thin film at P_In = 30 W exhibited the best p-type conductivity with Hall mobility of 6.87 cm²V^?1s^?1, which is a potential material as the absorption layer of high-performance solar cells.     

Formation mechanism of hydride precipitation in commercially pure titanium

Since titanium has high affinity for hydrogen and reacts reversibly with hydrogen,the precipitation of titanium hydrides in titanium and its alloys cannot be ignored.Two most common hydride precipitates in α-Ti matrix are γ-hydride and δ-hydride,however their mechanisms for precipitation are still unclear.In the present study,we find that both γ-hydride and δ-hydride phases with different specific orienta-tions were randomly precipitated in the as-received hot forged commercially pure Ti.In addition,a large amount of the titanium hydrides can be introduced into Ti matrix with selective precipitation by using electrochemical treatment.Cs-corrected scanning transmission electron microscopy is used to study the precipitation mechanisms of the two hydrides.It is revealed that the γ-hydride and δ-hydride precipita-tions are both formed through slip + shuffle mechanisms involving a unit of two layers of titanium atoms,but the difference is that the γ-hydride is formed by prismatic slip corresponding to hydrogen occupy-ing the octahedral sites of α-Ti,while the δ-hydride is formed by basal slip corresponding to hydrogen occupying the tetrahedral sites of cα-Ti.     

Synthesis and photocatalytic performance of MoS2/Polycrystalline black phosphorus heterojunction composite

As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS₂ as a cocatalyst to synthesize BP/MoS₂ catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS₂ can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS₂ catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h^?1 g^?1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts.     

Morphological and optical properties of PdxAg1-x alloy nanoparticles

Alloy nanoparticles (NPs) can offer a wide range of opportunities for various applications due to their composition and structure dependent properties such as multifunctionality, electronic heterogeneity, site-specific response, and multiple plasmon resonance bands. In this work, the fabrication of self-assembled Pd_xAg_1-x NPs alloy nanostructures with distinct size, density, shape, and composition is demonstrated via the solid-state dewetting of sputtered Pd/Ag thin films on c-plane sapphire. The initial stage of bilayer dewetting exhibits the nucleation of voids, followed by the expansion of voids and cluster breakdown and finally shape transformation along with the temperature control. Bilayer composition shows a substantial influence on the dewetting such that the overall dewetting is enhanced along with the increased Ag composition, i.e. Pd_0.25Ag_0.75 > Pd_0.5Ag_0.5 > Pd_0.75Ag_0.25. On the other hand, the size and density of NPs can be efficiently controlled by varying the initial thickness of bilayers. Reflectance peaks in UV and near-infrared (NIR) regions and a wide absorption band in the visible region arisen from the surface plasmon resonance are observed in reflectance spectra. The peak intensity depends on the composition of Pd_xAg_1-x NPs and the NIR peaks gradually blue-shift with the size decrement.     

P204树脂和阳离子交换树脂分离Sc与裂变产物

P204对Sc有很好的分离选择性和分离能力，但由于反萃困难限制了其在Sc纯化中的应用。本工作研究了从裂变产物中分离纯化Sc的方法，建立流程如下：首先利用P204树脂对Sc的强萃取能力，将Sc与大量裂变产物分离，再通过灰化方法破坏树脂官能团，解决了吸附在P204树脂上的Sc难以解吸的问题，最后通过阳离子交换树脂实现Sc与残留Zr和Mo的分离，从而实现了Sc与裂变产物的分离。该方法对样品体积和酸度要求低，流程步骤操作简单。通过对模拟样品进行分析，Sc的回收率大于65%，对主要裂变产物的去污因子大于10³，适用于Sc与裂变产物的分离。     

Flexible piezoelectric energy harvesters with graphene oxide nanosheets and PZT-incorporated P(VDF-TrFE) matrix for mechanical energy harvesting

Flexible piezoelectric energy harvesters (PEHs) have attracted extensive interest because of their ability to transform mechanical energy into electric power. Here, PEHs were fabricated using P(VDF-TrFE)-based piezoelectric composite films containing lead zirconate titanate (PZT) powder and –OH-functionalized graphene (HOG) nanosheets (HOG-P/P). Among all composites, a high open-circuit voltage (Voc) of approximately 50 V_p-p and a maximum power density of 1.4 μW/cm² were obtained from a HOG-P/P PEH with 0.10 wt% HOG nanosheets and 15 wt% PZT under bending–releasing mode. Moreover, the PEH exhibited a stable voltage output after 3000 bending–releasing cycles. In addition, the PEH harvested mechanical energy from human body movements and generated an output voltage and current of 60 V and 8 μA during the finger bending–releasing process, lighting up 30 commercial white LEDs. The enhanced piezoelectric performance can be attributed to the introduction of HOG nanosheets and PZT powder. This work provides an effective strategy for improving the output performance of P(VDF-TrFE)-based PEHs.     

Use of heat-moisture treated maize starch to modify the properties of wheat flour and the quality of noodles

Waxy, normal and high-amylose maize starches were subjected to heat-moisture treatment (HMT) and then added to wheat flour (WF) in different ratios (1%, 5% and 10%). The properties of blends and their cooked noodles were studied to investigate the effects of HMT starches. The incorporation of HMT starch in WF led to an increase in swelling power, peak viscosity and breakdown and to a decrease in setback, thus inhibiting retrogradation, hence enhancing resultant noodle softness. Compared to the same addition ratio of native starch to WF, HMT starch led to higher tensile strength and extensibility in resultant noodles. WF with added HMT starch had higher resistant starch than with native starch. This study showed that addition of HMT maize starch has potential to bring nutritional benefits. However, it is necessary to select the proper blending ratio and amylose content of starch to add, in consideration of its effect on noodle quality.     

基于复合养老模式的城市社区的基本概念与构建模式

本文从建立复合养老模式的必要性入手,分析养老职能社会化和养老模式多元化的趋势以及目前社区养老存在的不足,提出适应未来常态化养老需求的复合型养老模式的概念,并在此基础上论述其特征、构建原则和三种不同角度的基本构建模式。     

优化军工科研项目管理的具体策略

我国的军工科研所成立于上世纪，它以军工项目的科研、预研为主，为我国的国防军工提供研发产品。伴随着我国经济实力的增强和科技军事力量的增长，军工科研院所也转变了原有的工业专属性质，走上了军民两用、寓军于民的道路，并在时代的进步中成为了我国先进装备制造业的重要科研力量和科技创新支柱。凸现军事工业“高、精、尖”的特点，以项目管理的优化为具体策略进行军工科研开发工作。