不同双层结构AlCrN/AlCrVN多层涂层的力学和磨损性能

采用电弧离子镀的方法制备了不同数目（1、2、4、6）双层结构的AlCrN/AlCrVN多层涂层,并研究了多层结构对涂层微观结构、力学、摩擦学和切削性能的影响。结果显示,沉积态AlCrN/AlCrVN多层涂层主要由固溶(Al,Cr)N组成,优先生长方向为[111]晶向。与其他多层涂层相比,具有6层双层结构的AlCrN/AlCrVN涂层在高温下表现出较低的摩擦系数（约0.46）和磨损率（0.15×10^-11 m³/N·m）,以及较高的硬度（HK_0.05=38 000 MPa）和膜-基结合强度（L_C2=53±1 N）。多层涂层相邻层之间形成了较多的界面,有助于提高多层涂层的硬度和耐磨性。切削试验结果显示,当切削磨损标准VB=0.2时,AlCrN/AlCrVN-6涂层具有较高的硬度和耐磨性,最长的切削长度为7.4 m。     

Retrospective of ecological approaches to excess sludge reduction

The problem of excess sludge handling produced during wastewater treatment is undeniable reality of grave concern with increasingly stringent legislations. The sludge synthesis yield being 0.4-0.6 kgVSS/kgCOD (0.57-0.8 kgCODcell/kgCOD), results in high power consumption on its digestion and therefore taken considerable attention to achieve sustainable strategies.Solids reduction by physico-chemical methods results in buildup of chemicals. This may present risk to the environment and may require further treatment to remove the chemicals of concern in future. Wastewater sludge reduction upto 100% by biological, sustainable, non-hazardous, and environment friendly methods has been successfully tested at different levels. Therefore, above reasons were sufficient driving forces to confine this review to non-chemically assisted processes. Similarly, the thermally assisted processes result in high carbon footprint and excluded from the scope of this review. Enough has been reviewed on sludge reduction, as numbers of articles on the same subject with different angles have been reported, still the progress in the last few years is missing; hence, special emphasis is given herewith to highlight the efforts of the last five years.     

Layer‐by‐layer fabrication of nacre inspired epoxy/MMT multilayered composites

The organic–inorganic hybrid multilayered composites are prepared using a unique combination of poly[(o‐cresyl glycidyl ether)‐co‐formaldehyde] (CNER), amino modified montmorillonite (NH₂‐MMT), and polyethyleneimine (PEI). This tricomponent composite multilayer PEI(CNER/NH₂‐MMT/PEI)_n deposited via layer ‐ by ‐ layer technique is based upon synergistic combination of covalent and hydrogen bonding. The growth of multilayer was monitored using UV–vis spectroscopy and ellipsometry. When subjected to optical analyses, the prepared multilayered composite films revealed profound optical transmittance ～83%–87%. The surface morphological analysis by atomic force microscopy and scanning electron microscopy revealed uniform arrangement of organic–inorganic components with relative increase in intensity of elements (C, N, O, Si) as confirmed by X‐ray photoelectron spectroscopy studies. The multilayered composites possess 1.99 GPa hardness making them potential candidate for a number of applications where mechanical strength is desired. Moreover, significant resistance against alkaline and organic solvents at minimal deterioration of circa 0.12% has also been observed for the prepared films. The epoxy clay based thin films being robust, scratch resistant, hydrophilic, chemically inert, and mechanically strong are potential candidates for advanced environmental applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46079.     

Novel synthesis and antimicrobial studies of nanoscale titania particles

In the present investigation, a novel strategy of continuous microwave assisted flow synthesis (CMFS) has been adopted in comparison to traditional synthesis procedures (sol-gel and chemical precipitation method) for the quick production of TiO₂ nanoparticles with very fine particle properties. The X-ray powder diffraction analysis (XRPD) and transmission electron microscopy (TEM) were two techniques used for analysing the properties related to structure and particle morphology of the resultant samples. It was observed that the particles formed by using continuous flow route were less agglomerated, and particle size (~ 6?nm) was smaller in comparison with others obtained using sol-gel (~ 9?nm) and chemical precipitation method (~ 15?nm). X-ray diffraction impressions established the generation of Anatase phase with preferential [101] dimension. Zeta potential computations were taken to inspect the colloidal stability of nanoparticles. Antimicrobial nature of TiO₂ nano-samples was analyzed by using various bacterial and fungal strains. The nanostructured TiO₂ particles confirmed outstanding uniformity with respect to chemical and structure. This new ceramic substance with strong antimicrobial activity promised magnificent potential in bone tissue engineering.     

Membranes for CO2 /CH4 and CO2/N2 Gas Separation

Membrane technology has emerged as a leading tool worldwide for effective CO₂ separation because of its well-known advantages, including high surface area, compact design, ease of maintenance, environmentally friendly nature, and cost-effectiveness. Polymeric and inorganic membranes are generally utilized for the separation of gas mixtures. The mixed-matrix membrane (MMM) utilizes the advantages of both polymeric and inorganic membranes to surpass the trade-off limits. The high permeability and selectivity of MMMs by incorporating different types of fillers exhibit the best performance for CO₂ separation from natural gas and other flue gases. The recent progress made in the field of MMMs having different types of fillers is emphasized. Specifically, CO₂/CH₄ and CO₂/N₂ separation from various types of MMMs are comprehensively reviewed that are closely relevant to natural gas purification and compositional flue gas treatment     

Waste glass in civil engineering applications—A review

Each year, hundreds of thousands of tons of industrial wastes are being stockpiled, landfilled, and disposed of in storages occupying large areas of land that would otherwise be available for productive use. Recycling of such wastes is now becoming of urgent global interest due to an increasing population, the rise in anthropogenic activities, and the need for more efficient resource and waste management systems. Among many wastes, the generation of glass is dramatically increasing, particularly in the municipal, industrial, and construction sectors. In civil engineering, in general, crushed waste glass has been mainly investigated as a substitute for sand and fine-grained aggregate in concrete production. In geotechnical engineering, in particular, the application of glass wastes is mainly limited to road pavements or as an additive to different soils for subgrade improvement. While glass wastes are relatively inert and potentially offer several opportunities for recycling as a substitute for diminishing and increasingly expensive sand supplies, their potential use yet remains relatively under-researched. This paper systematically reviews the current status of knowledge on the use of glass wastes in various civil engineering applications and discusses the suitability assessment of waste glass for use as a sustainable alternative to traditional civil engineering materials.     

The dynamics of three-mode coupling in a trapped Bose gas

ABSTRACT

Multiple mode couplings in topological coherent modes of Bose–Einstein condensate are considered, by introducing an external alternating (resonating) field in the system. This analysis is based on the analytical solutions of nonlinear Gross–Pitaevskii equation for a trapped Bose gas at nearly absolute zero temperature. The dynamics of fractional populations of the generated coherent modes are analysed, particularly for a three-level system in the limit of small to large detuning of the intermediate state. These coupled topological modes, though nonlinear, are analogous to a resonant atom and exhibit a variety of significant non-trivial phenomena (effects), like: dynamic phase transitions, interference patterns, critical phenomena, mode-locking and chaotic motion.     

Statistical Modeling and Analysis of Mobile-to-Mobile Fading Channels in Cooperative Networks Under Line-of-Sight Conditions

Recently, mobile-to-mobile (M2M) cooperative network technology has gained considerable attention for its promise of enhanced system performance with increased mobility support. As this is a new research field, little is known about the statistical properties of M2M fading channels in cooperative networks. So far, M2M fading channels have mainly been modeled under the assumption of non-line-of-sight (NLOS) conditions. In this paper, we propose a new model for M2M fading channels in amplify-and-forward relay links, where it is assumed that a line-of-sight (LOS) component exists in the direct link between the source mobile station and the destination mobile station. Analytical expressions will be derived for the main statistical quantities of the channel envelope, such as the mean value, variance, probability density function (PDF), level-crossing rate (LCR), and average duration of fades (ADF) as well as the channel phase. Our results show that the statistical properties of the proposed M2M channel are quite different from those of double Rayleigh and double Rice channels. In addition, a high-performance channel simulator will be presented for the new M2M channel model. The developed channel simulator is used to confirm the correctness of all obtained theoretical results by simulations.