用响应面法进行压缩机环状管*的设计优化

从结构振动和结构噪声的角度来看,压缩机的环状管是电冰箱中最重要的部件。压缩机内部机体产生的振动能量通过环状管传到壳体和外界,因此压缩机环状管的设计非常重要。但是,由于环状管几何形状的复杂性和运动的非线性,分析和设计环状管十分困难,往往不得不用统计法和试验法进行系统设计。对于类似环状管这样的复杂系统,响应面法(RSM)是常用的建模技术。用有限元模型和简单的试验模型代替环状管的实际模型作为环状管优化的起点。建立RS模型以后,用Sensitivity-based优化法进行优化。采用动态最小二乘法(MLSM)减少逼近误差。     

Influence of bearing damping on instability of asymmetric shafts, part IV: Effects of fluid-film bearings

The influence of fluid-film bearings on the parametric instability of asymmetric shafts is investigated. Since fluid-film bearings may have non-isotropic stiffness and damping, the system equations are time-varying coefficients in a rotating reference frame and the complete solution of transition curves includes coupled modes. Thus, the analytical modal method provided by our previous studies has been modified in this part for the determination of approximate solutions from a truncated Hill's determinant. In numerical examples, a plain cylindrical type and a tilting four-pad type are considered to estimate the effects of bearing parameters concerning static load, oil viscosity, and clearance on unstable regions.     

Preparation of Mo2C by MPCVD and Its Photocatalytic Properties

Mo2C was prepared by microwave plasma chemical vapor deposition(MPCVD)technique with the power of 800 W and pressure of 18 kPa. Compared with traditional prepar...     

A Flower-like In2O3 Catalyst Derived via Metal–Organic Frameworks for Photocatalytic Applications

The most pressing concerns in environmental remediation are the design and development of catalysts with benign, low-cost, and efficient photocatalytic activity. The present study effectively generated a flower-like indium oxide (In₂O₃-MF) catalyst employing a convenient MOF-based solvothermal self-assembly technique. The In₂O₃-MF photocatalyst exhibits a flower-like structure, according to morphology and structural analysis. The enhanced photocatalytic activity of the In₂O₃-MF catalyst for 4-nitrophenol (4-NP) and methylene blue (MB) is likely due to its unique 3D structure, which includes a large surface area (486.95 m² g⁻¹), a wide spectrum response, and the prevention of electron–hole recombination compared to In₂O₃-MR (indium oxide-micro rod) and In₂O₃-MD (indium oxide-micro disc). In the presence of NaBH₄ and visible light, the catalytic performances of the In₂O₃-MF, In₂O₃-MR, and In₂O₃-MD catalysts for the reduction of 4-NP and MB degradation were investigated. Using In₂O₃-MF as a catalyst, we were able to achieve a 99.32 percent reduction of 4-NP in 20 min and 99.2 percent degradation of MB in 3 min. Interestingly, the conversion rates of catalytic 4-NP and MB were still larger than 95 and 96 percent after five consecutive cycles of catalytic tests, suggesting that the In₂O₃-MF catalyst has outstanding catalytic performance and a high reutilization rate.     

Combination of Sanguisorbigenin and Conventional Antibiotic Therapy for Methicillin-Resistant Staphylococcus aureus: Inhibition of Biofilm Formation and Alteration of Cell Membrane Permeability

Methicillin-resistant Staphylococcus aureus (MRSA) infection is challenging to eradicate because of antibiotic resistance and biofilm formation. Novel antimicrobial agents and alternative therapies are urgently needed. This study aimed to evaluate the synergy of sanguisorbigenin (SGB) isolated from Sanguisorba officinalis L. with six conventional antibiotics to achieve broad-spectrum antibacterial action and prevent the development of resistance. A checkerboard dilution test and time-to-kill curve assay were used to determine the synergistic effect of SGB combined with antibiotics against MRSA. SGB showed significant synergy with antibiotics and reduced the minimum inhibitory concentration of antibiotics by 2–16-fold. Biofilm inhibition assay, quantitative RT-PCR, crystal violet absorption, and transmission electron microscopy were performed to evaluate the synergy mechanism. The results indicated that SGB could inhibit biofilm formation and alter cell membrane permeability in MRSA. In addition, SGB was found to exhibit quite low cytotoxicity and hemolysis. The discovery of the superiority of SGB suggests that SGB may be an antibiotic adjuvant for use in combination therapy and as a plant-derived antibacterial agent targeting biofilms.     

Coating of TiO2 nanoparticles with PbS thin films and preparation of PbS nanoparticles using a one-pot sonochemical reaction under the multibubble sonoluminescence conditions

Preparations of PbS-coated titanium dioxide (TiO₂) and lead sulfide (PbS) nanoparticles under ultrasonic field at the multibubble sonoluminescence (MBSL) conditions were tested in water solutions. Under the optimal MBSL conditions (20 kHz and 220 W power input), PbS nanoparticles (diameter = 40-50 nm) were prepared by treating lead nitrate and thioacetamide for 20 min in water solutions. The size of PbS nanoparticles was found to be easily increased to about 90 nm in diameter by increasing the reactant concentration twice. A similar sonochemical reaction with TiO₂ nanoparticles (about 20-30 nm in diameter) gave rise to PbS-coated TiO₂ nanoparticles with a core/shell structure. The PbS thin film coating was quite uniform and the average coating depth of PbS on the TiO₂ nanoparticles was about 2-3 nm under the described conditions. It is interesting to note that the coating depth was found to be controlled to 2-10 nm range by increasing the amounts of reactants for Pb and S twice with a sonication time of 30 min.     

Studied on a novel human keratinocyte membrane delivery system in vitro

The culture of keratinocytes on flexible membranes has been proposed as a means to simplify, accelerate and improve the efficiency with which proliferating cells are delivered to full thickness or non-healing skin defects. The purpose of this article was to study the ability of chitosan-gelatin manbranes to facilitate the growth of human keratinocytes. The membranes with different chitosan contents were studied. The surface properties of chitosan-gelatin membranes were investigate by SEM, and water contact angle test. The mechanical property of the membranes was tested. Data implied that gelatin could make the membranes more flexible and hydrophilic than chitosan membranes, which may regulate the seeded cells behavior. Loading human keratinocytes on chitosan-gelatin membranes, cells attachment, spread, and growth were investigated by light microscopy, SEM, and MTT test. The results suggested that the adhesion and proliferation of keratinocytes seeded on chitosan-gelatin membranes were same as on tissue culture plate, in which gelatin could modify the interaction between keratinocytes and chitosan membranes. Therefore, chitosan-gelatin membrane is a good candidate for keratinocytes delivery system.     

地埋管地源热泵水系统的若干问题研究

结合调研测试的实际工程,根据实际工程中地埋管地源热泵系统中水系统的形式及特点,归纳了设计、运行管理、设备故障等几个方面的水系统常见的问题。探讨了地埋管地源热泵水系统的设计问题,指出某些工程水系统存在的问题及解决思路;分析水系统故障的原因及表现,通过对水系统运行状态的观察与测试,从机组COP及系统能效比的角度分析水系统故障的影响：对于运行管理方面,提出相应的水系统形式的运行建议,为优化地埋管地源热泵的设计及运行管理提供了相应参考。     

Creation of Nonspherical Microparticles through Osmosis‐Driven Arrested Coalescence of Microfluidic Emulsions

Droplet‐based microfluidics enable the production of emulsions and microparticles with spherical shapes, but the high‐throughput fabrication of nonspherical emulsions and microparticles still remains challenging because interfacial tension plays a dominant role during preparation. Herein, ionic liquids (ILs) containing salts, which possess sufficient osmotic pressure to realize water transport and phase separation, are introduced as inner cores of oil‐in‐oil‐in‐water double emulsions and it is shown that nonspherical emulsions can be constructed by osmosis‐driven arrested coalescence of inner cores. Subsequently, ultraviolet polymerization of the nonspherical emulsions leads to nonspherical microparticles. By tailoring the number, composition, and size of inner cores as well as coalescence time, a variety of nonspherical shapes such as dumbbell, rod, spindle, snowman, tumbler, three‐pointed star, triangle, and scalene triangle are created. Importantly, benefitting from excellent solvency of ILs, this system can serve as a general platform to produce nonspherical microparticles made from different materials. Moreover, by controlling the osmotic pressure, programmed coalescence of inner cores in double emulsions is realizable, which indicates the potential to build microreactors. Thus, a simple and high‐throughput strategy to create nonspherical microparticles with arrested coalescence shapes is developed for the first time and can be further used to construct novel materials and microreactors.