Polyelectrolyte mediated scalable synthesis of highly stable silver nanocubes in less than a minute using microwave irradiation

Silver nanocubes were synthesized for the first time in large quantities on gold seed in the presence of a polyelectrolyte using microwave heating for 60-120?s. Our experiment indicates that the polyelectrolyte directs the growth of the particle in a specified crystallographic direction resulting in the faceted particle, i.e.?a nanocube. The nanocubes are stable for at least 2 months in ambient conditions.     

Morphology Engineering in Monolayer MoS2‐WS2 Lateral Heterostructures

In recent years, heterostructures formed in transition metal dichalcogenides (TMDs) have attracted significant attention due to their unique physical properties beyond the individual components. Atomically thin TMD heterostructures, such as MoS₂‐WS₂, MoS₂‐MoSe₂, MoS₂‐WSe₂, and WSe₂‐WS₂, are synthesized so far via chemical vapor deposition (CVD) method. Engineering the morphology of domains including size and shape, however, still remains challenging. Here, a one‐step CVD strategy on the morphology engineering of MoS₂ and WS₂ domains within the monolayer MoS₂‐WS₂ lateral heterostructures through controlling the weight ratio of precursors, MoO₃ and WO₃, as well as tuning the reaction temperature is reported. Not only can the size ratio in terms of area between WS₂ and MoS₂ domains be easily controlled from less than 1 to more than 20, but also the overall heterostructure size can be tuned from several to hundreds of micrometers. Intriguingly, the quantum well structure, a WS₂ stripe embedded in the MoS₂ matrix, is also observed in the as‐synthesized heterostructures, offering opportunities to study quantum confinement effects and quantum well applications. This approach paves the way for the large‐scale fabrication of MoS₂‐WS₂ lateral heterostructures with controllable domain morphology, and shall be readily extended to morphology engineering of other TMD heterostructures.     

Nanosize cobalt oxides as anode materials for lithium-ion batteries

Nanosize cobalt oxides (Co₃O₄) were synthesised by chemical decomposition of cobalt octacarbonyl in toluene at low temperature. Electrochemical properties of as-prepared Co₃O₄ as anodes in Li-ion cells were tested. The nanosized Co₃O₄ electrode demonstrate a stable reversible lithium storage capacity of 360 mAh/g within 30 cycles. The reactivity of as-prepared Co₃O₄ in Li-ion cells could be attributed to nanosize particles of Co₃O₄ and its lithiation products.     

The corrosion of Co-Nb alloys in reducing/oxidizing-sulfidizing gases at 600–800°C

The corrosion of the two pure metals and of two alloys containing 15 and 30 wt% Nb has been studied at 600–800°C in H₂-H₂S-CO₂ gas mixtures providing 10⁻⁸ atm S₂ at all temperatures and 10⁻²⁴ atm O₂ at 600°C and 10⁻²⁰ atm O₂ at 700 and 800°C. The corrosion kinetics were rather complex, being sometimes parabolic and in other cases nearly linear. Under a constant temperature the addition of niobium generally reduced the corrosion rate, except at 700°C when pure cobalt corroded more slowly than the two alloys. The corrosion rates for the same material decreased with an increase in temperature under the same sulfur pressure. Except at 800°C under 10⁻⁸ atm S₂, which is below the dissociation pressure of cobalt sulfide, the scales presented an outer layer of pure cobalt sulfide and an inner layer of complex composition containing a mixture of double sulfide, niobium oxide and in some cases of unreacted metallic cobalt particles. The addition of niobium was generally beneficial, the effect increasing with its concentration in the alloy, but the corrosion rates of the alloys were still much higher than that of pure niobium, mainly as a result of the lack of formation of a protective layer of niobium sulfide. The corrosion behavior is examined with special reference to the consequences of the low solubility of niobium in cobalt and to the relation between the microstructure of the alloys and the scales.     

FDS在VR场景设计中的应用

摘 要：为了完成内设火灾场景的优化,运用FDS数值模拟软件,对每个场景房间内的温度、能见度及烟气扩散过程进行模拟,以数据、图片、视频的形式输出计算结果。参考数值模拟计算结果,对VR场景进行构建和优化,使得场景中的火灾发展过程更科学真实,进一步增强使用者的体验感和沉浸感。同时,FDS数值计算可以解决大场景火灾缺乏现实数据的问题,为系统的优化升级提供技术支持和数据支撑。     

EFFECT OF HEAT TREATMENT ON MECHANICAL PROPERTIES OF 0Cr12Mn5Ni4Mo3Al

In this work, the effect of solid soluble temperature, cold treating temperature and ag-ing temperature on the mechanical properties of 0Cr12Mn5Ni4Mo3Al had been inves-tigated systemically. The results show that under the optimal parameters (solid solubletreatment 1050℃×40min, cold treatment -78℃×4h, aging treatment 520℃×2h) theproperties (strength and tenacity) could be up to its maximum.     

The Internal Oxidation of Ternary Alloys. VI: The Transition from Internal to External Oxidation of the Most-Reactive Component under Intermediate Oxidant Pressures

The conditions for the transition from internal to external oxidation of the most-reactive component C of ternary A–B–C alloys are examined, assuming the presence of external scales of the oxide of the component of intermediate reactivity B. For this, approximate expressions for the diffusion coefficient of oxygen and for the concentration of oxygen dissolved in the binary A–B alloy matrix within the zone of internal oxidation as functions of the composition of the metal matrix within the zone of internal oxidation are used. Numerical calculations of the critical content of C needed for this transition are carried out for different combinations of values of the various parameters involved. The results obtained for the ternary alloys are compared with the corresponding data calculated for the binary A–C and B–C alloys under oxygen pressures insufficient to oxidize the most-noble alloy component. This allows to predict the possibility of existence of a third-element effect under intermediate oxidant pressures.     

熔融石英陶瓷材料的晶化抑制研究

以粒径〈0．16mm的熔融石英颗粒为原料，以硼酸、碳化硅、氮化硅、水玻璃为晶化抑制剂，以聚乙烯醇（浓度1％）为结合剂，试样成型压强为20MPa，试样经1200℃保温2h烧成，对烧后试样进行1500℃保温1h的强化脱玻处理、RT～1300℃的差热分析以及RT～1300℃的热膨胀测定。试验发现：引入碳化硅或水玻璃对熔融石英的析晶抑制作用不明显，而引入5％的硼酸或引入3％的氮化硅可有效抑制熔融石英的析晶。     

Corrosion of Three Commercial Steels Under ZnCl2 –KCl Deposits in a Reducing Atmosphere Containing HCl and H2S at 400–500°C

The corrosion of three commercial steels in a reducing atmosphere containing HCl plus H₂S in the presence of ZnCl₂–KCl deposits has been investigated at 400–500°C and compared with the corrosion of the same materials in a similar gas mixture free from H₂S. The presence of H₂S in the gas accelerated the corrosion of the three commercial steels beneath ZnCl₂–KCl deposits. All materials suffered from severe corrosion with partial detachment and spalling of the external scales. Degradation of the steels resulted from the penetration of chlorine-containing species through the scale formed initially down to the metal matrix, because chorine-rich species were detected close to the alloy/scale interface. Although the corrosion resistance generally increased with increasing Cr content, even the high-Cr stainless steel SS304 is still unable to provide good corrosion resistance against the ZnCl₂–KCl deposits in the presence of H₂S due to the bad adherence of the scales to the alloy. The mechanisms of attack are discussed on the basis of thermodynamic considerations and of the active-oxidation model.     

二甲醚燃料的生产及应用

甲醇催化脱水可得二甲醚。它可用作化工原料，气雾剂汝民用燃料。本文介绍燃料级二甲醚的生产及二甲醚液化气、醇－醚燃料的应用概况。