Analysis of Dynamic Processes in Biological Systems Using Acousto-Optic Video Spectrometry

Journal of Communications Technology and Electronics - A measurement setup based on a transmission microscope with double acousto-optical wavelength selection is proposed for detection of...     

Modelling of metal hydride hydrogen compressors from thermodynamics of hydrogen – Metal interactions viewpoint: Part II. Assessment of the performance of metal hydride compressors

Performance of the thermally-driven metal hydride hydrogen compressor (MHHC) is defined by (a) its H₂ compression ratio and maximum output H₂ pressure; (b) throughput productivity/average output flow rate; (c) specific thermal energy consumption which determines H₂ compression efficiency. In earlier studies, the focus of the R&D efforts was on the optimisation of the design of the MH containers and heat and mass transfer in the MH storage and compression system aimed at shortening the time of the H₂ compression cycle. This work considers an important but insufficiently studied aspect of the development of the industrial-scale thermally driven MHHC's – selection of the materials and optimisation of the materials performance. Further to the operation in the specified pressure/temperature ranges, materials selection should be based on the estimation of the productivity of the compression cycle, and specific heat consumption required for the H₂ compression, which together determine the process efficiency.The current work presents a model to determine productivity and heat consumption for a single- and multi-stage MHHC's which is based on use of Pressure – Composition – Temperature (PCT) diagrams of the utilized metal hydrides at defined operating conditions – temperatures and hydrogen pressures – and main operational features of the MHHC (number of stages, amounts of the MH materials used, cycle time). In Part I of this work [Lototskyy, Yartys, et al., Int J Hydrogen Energy, DOI: 10.1016/j.ijhydene.2020.10.090], we showed that the calculated cycle productivities significantly vary for the different materials. Analysis of the system performance carried out in this work (Part II) shows that the throughput productivity and efficiency of a multi-stage MHHC also depends on the types and amounts of the used MH materials in the multi-stage compressor layout. This has been analysed for a number of the most practically important AB₅ and Laves type AB₂ hydrogen storage alloys integrated into the MHHC's.A comparison of experimentally measured performances of single-, two- and three-stage industrial-scale MHHC's developed by the authors earlier shows their satisfactory agreement with the modelling results thus demonstrating a high value of the presented method for the proper materials selection during development of the MHHC. As an important future development, the work presents a performance evaluation of a two-stage MHHC for H₂ compression operating in the pressure range from 30 to 500 atm at operating temperatures between 20 and 150 °C.     

OPTE special issue on PDE-constrained optimization

Optimization and Engineering -     

Prediction of time series using wavelet Gaussian process for wireless sensor networks

Wireless Networks - The detection and transmission of a physical variable over time, by a node of a sensor network to its sink node, represents a significant communication overload and consequently...     

Protected bis(hydroxyorganyl) polysulfides as modifiers of Li/S battery electrolyte

The protected bis(hydroxyorganyl) polysulfides synthesized have been tested as modifiers of electrolyte of lithium-sulfur rechargeable batteries. The best result (35% increase of the battery capacity at the 50th cycle) was attained using 5 wt.% of 2,2,12,12-tetramethyl-4,10-diphenyl-3,11-dioxa-6,7,8-trithia-2,12-disilatridecane. Bis(hydroxyorganyl) polysulfides protected at the hydroxyl group have been synthesized for the first time by the reaction of oxiranes with sodium polysulfide (ethanol, NaHCO₃, 12 h, 20–25 °C) in yield 21–87%. For the hydroxyl protection in the hydroxy polysulfides, the acetal, tri(methyl)silyloxy or tri(ethoxy)silyl protecting groups were employed.     

Dancing with the Cells: Acoustic Microflows Generated by Oscillating Cells

The interaction of a sound or ultrasound wave with an elastic object, such as a microbubble, can give rise to a steady‐state microstreaming flow in its surrounding liquid. Many microfluidic strategies for cell and particle manipulation, and analyte mixing, are based on this type of flow. In addition, there are reports that acoustic streaming can be generated in biological systems, for instance, in a mammalian inner ear. Here, new observations are reported that individual cells are able to induce microstreaming flow, when they are excited by controlled acoustic waves in vitro. Single adherent cells are exposed to an acoustic field inside a microfluidic device. The cell‐induced microstreaming is then investigated by monitoring flow tracers around the cell, while the structure and extracellular environment of the cell are altered using different chemicals. The observations suggest that the maximum streaming flow induced by an MDA‐MB‐231 breast cancer cell can reach velocities on the order of mm s^?1, and this maximum velocity is primarily governed by the overall cell stiffness. Therefore, such cell‐induced microstreaming measurements, including flow pattern and velocity magnitude, may be used as label‐free proxies of cellular mechanical properties, such as stiffness.     

Residual strength estimation of a laminated composite with barely visible impact damage based on topology optimization

Structural and Multidisciplinary Optimization - The purpose of this study is to develop an approach to generate reasonably conservative estimations of the residual strength of a composite material...