The Chemistry of the Noncrystalline State

This article sets out to describe and account for the chemical and physical consequences of the presence of gross disorder in solids. Knowledge of the structure of such disordered materials is an obvious prerequisite to a further understanding of other properties and behavior, and our current knowledge of the structure of various noncrystalline systems is discussed together with the experimental techniques which need to be employed in order to obtain such information. The so-called glass transition, which takes place as a liquid is supercooled below the crystallization temperature, is discussed in terms of the various models which have been proposed to account for this phenomenon. The effect of noncrystallinity on electronic properties is also discussed, and we highlight new developments in the understanding of electron localization and transport processes. Finally, two applications of amorphous solids are considered in some detail: optical fibers for use in communication networks and “superionic” glasses for possible use in solid-state batteries.     

Multiscale asymptotic method of optimal control on the boundary for heat equations of composite materials

In this paper, we study the optimal control on the boundary for parabolic equations with rapidly oscillating coefficients arising from the heat transfer problems and the optimal control on the boundary of composite materials or porous media. The multiscale asymptotic expansion of the solution for the problem in the case without any constraints is presented. We derive the proofs of all convergence results.     

Structural Analysis of Electroplated Amorphous-Nanocrystalline Ni-W

 Ductile nickel-tungsten (Ni-W) alloys containing about 20–21 at.%W were electroplated onto copper substrates. The development of the amorphous/nanocrystalline microstructure towards a complete crystallization by isochronal heat treatments in vacuum was monitored by different methods. For medium annealing temperatures a solid-solution of W in the fcc-Ni lattice was achieved resulting in an increased hardness. For temperatures of 600 °C and upward recrystallization started and thermodynamically stable intermetallic compounds like Ni₄W and NiW were formed. A third phase, containing more than 80 at.%W was also detected but could not be identified so far. Only by combination of different methods and especially by use of analytical TEM structural analysis and phase identification in these amorphous-nanocrystalline Ni-W alloys were successful.     

Influence of processing variables on the formation of La2Zr2O7 in transferred arc plasma torch processing

The transferred arc plasma (TAP) torch process has various noteworthy features such as extremely high temperatures, low environmental impact and short processing time which makes it the most suitable technique for synthesizing ceramic composite materials. Furthermore, it is a direct two-step technique which by its virtue of high temperature and power density paves way for high production rate. Hence in this study, an effort has been made to utilize the TAP torch processing technique for the bulk production of La₂Zr₂O₇ with time effectiveness from the mixture of La₂O₃ and ZrO₂ powders (1:2 mol ratios) which were ball milled for 4 h. For this purpose, transferred arc plasma torch was specially designed in laboratory scale level and the operating parameters were optimized in order to achieve maximum La₂Zr₂O₇ formation efficiency. In this study, the phase and microstructure formation of the processed samples was analyzed via X-ray diffraction (XRD) and scanning electron microscope (SEM) images respectively. Moreover, EDX analysis was incorporated to highlight the superior influence of the longer processing time on the stoichiometric ratio of ZrO₂/La₂O₃ in the processed sample as against input power and the gas flow rate.     

大学物理铁磁质教学中工程教育素材的融入

在大学物理课程铁磁质知识点的教学中,结合工程实践教育,使讲授的知识点能够理论联系实际,在提高教学效果的同时,使学生认识到理论知识在工程实践中的应用,进而使学生树立正确的知识价值观,提高学习兴趣,增强主动学习的意识.     

Co-salen functionalized on graphene as an efficient heterogeneous catalyst for cyclohexene oxidation

Co-salen functionalized on graphene with an average pore size of 27.7 nm as a heterogeneous catalyst exhibited good catalytic activity and recyclability in cyclohexene oxidation.     

Multi-Channel Optical Device for Solar-Driven Bacterial Inactivation under Real-Time Temperature Feedback

Solar-driven photothermal antibacterial devices have attracted a lot of interest due to the fact that solar energy is one of the cleanest sources of energy in the world. However, conventional materials have a narrow absorbance band, resulting in deficient solar harvesting. In addition, lack of knowledge on temperature change in these devices during the photothermal process has also led to a waste of energy. Here, we presented an elegant multi-channel optical device with a multilayer structure to simultaneously address the above-mentioned issues in solar-driven antibacterial devices. In the photothermal channel, semiconductor IrO₂-nanoaggregates exhibited higher solar absorbance and photothermal conversion efficiency compared with nanoparticles. In the luminescence channel, thermal-sensitive Er-doped upconversion nanoparticles were utilized to reflect the microscale temperature in real-time. The bacteria were successfully inactivated during the photothermal effect under solar irradiation with temperature monitoring. This study could provide valuable insight for the development of smart photothermal devices for solar-driven photothermal bacterial inactivation in the future.