Capillary tube selection for HCFC22 alternativesSélection de capillaires pour les frigorigènes de remplacement du HCFC22

In this paper, pressure drop through a capillary tube is modeled in an attempt to predict the size of capillary tubes used in residential air conditioners and also to provide simple correlating equations for practicing engineers. Stoecker's basic model was modified with the consideration of various effects due to subcooling, area contraction, different equations for viscosity and friction factor, and finally mixture effect. McAdams' equation for the two-phase viscosity and Stoecker's equation for the friction factor yielded the best results among various equations. With these equations, the modified model yielded the performance data that are comparable to those in the ASHRAE handbook. After the model was validated with experimental data for CFC12, HFC134a, HCFC22, and R407C, performance data were generated for HCFC22 and its alternatives, HFC134a, R407C, and R410A under the following conditions: condensing temperature; 40, 45, 50, 55°C, subcooling; 0, 2.5, 5°C, capillary tube diameter; 1.2–2.4 mm, mass flow rate; 5–50 g/s. These data showed that the capillary tube length varies uniformly with the changes in condensing temperature and subcooling. Finally, a regression analysis was performed to determine the dependence of mass flow rate on the length and diameter of a capillary tube, condensing temperature, and subcooling. Thus determined simple practical equations yielded a mean deviation of 2.4% for 1488 data obtained for two pure and two mixed refrigerants examined in this study.     

基于超导差分加速度测量原理的微推力测量方案

随着微推进技术的快速发展,微推力器推力的测试与标定也日益困难。为实现微推力的精密测量和动态特性测试,通过分析超导重力梯度仪的差分加速度测量原理、仪器的构成和原理电路等,提出了一种基于高温超导差分加速度测量原理和SQUID检测技术微推力测量方案,其推力测量范围为10^-7-10^-2N、测量频带从直流至4Hz。根据检验质量的动力学方程和超导回路磁通量守恒方程,导出了推力与输出差分电流的传递函数,分析了影响测量的主要噪声。方案可应用于微推力的测量,并有进一步提高推力测量精度的潜力。     

A study on the performance of multi-stage heat pumps using mixturesEtude sur la performance de pompes à chaleur multi-étagées utilisant des mélanges

Multi-stage heat pumps composed of a condenser, evaporator, compressor, suction line heat exchanger, and low and/or high stage economizers are studied by computer simulation. Their thermodynamic performance and design options are examined for various working fluids. In the simulation, HCFC22/HCFC142b and HFC134a are studied as an interim and long term alternatives for CFC12 while HFC32/HFC134a and HFC125/HFC134a are studied as long term alternatives for HCFC22. The results indicate that the three-stage super heat pump with appropriate mixtures is up to 27.3% more energy efficient than the conventional single-stage system with pure fluids. While many factors contribute to the performance increase of a super heat pump, the most important factor is found to be the temperature matching between the secondary heat transfer fluid and refrigerant mixture, which is followed by the use of a low stage economizer and suction line heat exchanger. The contribution resulting from the use of a high stage economizer, however, is not significant. With the suction line heat exchanger, the system efficiency increases more with the fluids of larger molar liquid specific heats. From the view point of volumetric capacity and energy efficiency, a 40%HCFC22/60%HCFC142b mixture is proposed as an interim alternative for CFC12 while a 25%HFC32/75%HFC134a mixture is proposed as a long term alternative for HCFC22.     

Thermodynamics of π–π Interactions of Benzene and Phenol in Water

The π–π interaction is a major driving force that stabilizes protein assemblies during protein folding. Recent studies have additionally demonstrated its involvement in the liquid–liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs). As the participating residues in IDPs are exposed to water, π–π interactions for LLPS must be modeled in water, as opposed to the interactions that are often established at the hydrophobic domains of folded proteins. Thus, we investigated the association of free energies of benzene and phenol dimers in water by integrating van der Waals (vdW)-corrected density functional theory (DFT) and DFT in classical explicit solvents (DFT-CES). By comparing the vdW-corrected DFT and DFT-CES results with high-level wavefunction calculations and experimental solvation free energies, respectively, we established the quantitative credibility of these approaches, enabling a reliable prediction of the benzene and phenol dimer association free energies in water. We discovered that solvation influences dimer association free energies, but not significantly when no direct hydrogen-bond-type interaction exists between two monomeric units, which can be explained by the enthalpy–entropy compensation. Our comprehensive computational study of the solvation effect on π–π interactions in water could help us understand the molecular-level driving mechanism underlying the IDP phase behaviors.     

High-Performance All-Solid-State Batteries Enabled by Intimate Interfacial Contact Between the Cathode and Sulfide-Based Solid Electrolytes

All-solid-state batteries (ASSBs) are considered the ultimate next-generation rechargeable batteries due to their high safety and energy density. However, poor Li-ion kinetics caused by the inhomogeneous distribution of the solid electrolytes (SEs) and complex chemo-mechanical behaviors lead to poor electrochemical properties. In this study, LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) (core) – Li₆PS₅Cl (LPSCl) SEs (shell) particles (NCM@LPSCl) are prepared by a facile mechano-fusion method to improve the electrochemical properties and increase the energy density of ASSBs. The conformally coated thin SEs layer on the surface of NCM enables homogeneous distribution of SEs in overall electrode and intimate physical contact with cathode material even under volume change of cathode material during cycling, which leads to the improvement in Li-ion kinetics without the increase in solid electrolyte content. As a result, an ASSBs employing NCM@LPSCl with 4 mAh cm⁻¹ specific areal capacity exhibits robust electrochemical properties, including the improved reversible capacity (163.1 mAh g⁻¹), cycle performance (90.0% after 100 cycles), and rate capability (discharge capacity of 152.69, 133.80, and 100.97 mAh g⁻¹ at 0.1, 0.2, and 0.5 C). Notably, ASSBs employing NCM@LPSCl composite show reliable electrochemical properties with a high weight fraction of NCM (87.3 wt%) in the cathode.     

Effect of set-type yoghurt supplemented with the novel probiotic Lantiplantibacillus plantarum 200655 on physicochemical properties and the modulation of oxidative stress-induced damage

Food Science and Biotechnology - The present study developed a functional yoghurt supplemented with Lantiplantibacillus plantarum 200655 and evaluated its physicochemical properties and antioxidant...     

Effects of COVID-19 on a CMOS fabrication course: An integrated design experience

In the CMOS fabrication course described herein, the lecture component provides the theoretical background for semiconductor materials and integrated circuit fabrication processes. The laboratory component provides the hands-on experience required to fabricate and electrically characterize CMOS circuits in a one-semester format. A strong semiconductor device process design thread is achieved in the course by integrating the laboratory experience and process simulation/modeling and theoretical calculations. The risks associated with the COVID-19 pandemic have forced significant course modifications. The lecture is switched to a remote learning format, including pre-recorded content and weekly advanced Q&A sessions. The laboratory provides both in-person and remote sessions. Approved social distancing and cleaning protocols are practiced in the facility for in-person learning. Complementary remote learning resources are made available to all the students such as pre-recorded laboratory instructions, live video-based laboratory sessions, and web-based supplementary information. Compared to pre-pandemic semesters, the average students' GPA of the pandemic period has increased, attributed to larger and archived volumes of instructional material. Overall student comments related to course changes necessitated by the pandemic are mixed with both positive and negative feedback.     

Fermentative effects by probiotic Lactobacillus brevis B7 on antioxidant and anti-inflammatory properties of hydroponic ginseng

Food Science and Biotechnology - Soil-cultivation presents environmental limitations and requires considerable labor, space, and water supply. Alternatively, hydroponically-cultured ginseng (HG)...     

Beyond probiotics: a narrative review on an era of revolution

Food Science and Biotechnology - Whether knowingly or unknowingly, humans have been consuming probiotic microorganisms through traditionally fermented foods for generations. Bacteria, like lactic...     

MAC: multimodal,attention-based cybersickness prediction modeling in virtual reality

Virtual Reality - Cybersickness is one of the greatest barriers to the adoption of virtual reality. A growing body of research has focused on identifying the characteristics of cybersickness and...