氯化钠对几种常见菌的抑制作用

文章主要研究了NaCl对几种常见菌的抑制作用,设计了梯度平板实验和肉汤增值实验.梯度平板实验表明:很低的NaCl浓度就能抑制假丝酵母和乳酸杆菌生长;NaCl溶液浓度大约在5%以下对大肠杆菌具有抑制作用;浓度大约为8.5%的NaCl溶液对金黄色葡萄球菌具有抑制作用.肉汤增值实验表明:浓度4%的NaCl溶液对大肠杆菌具有抑制作用,浓度1.5%的NaCl溶液对乳酸杆菌和假丝酵母具有明显抑制杀灭作用,浓度7.5%的NaCl溶液对枯草芽孢杆菌具有抑制作用,浓度10%的NaCl溶液对金黄色葡萄球菌具有抑制作用.实验结果为NaCl抑菌作用提供了数据支持,所设计的实验方法为进一步开展NaCl杀菌抑菌作用的研究奠定了基础.     

Fundamental study on adhesion of ice to cooling solid surface

Many technological troubles are caused by ice adhesion to a cooling solid wall (surface). Therefore, it is urgent to clarify a mechanism of ice adhesion.It is thought that ice adhesion to the cooling wall is governed by heat transfer and interfacial phenomena between ice and the wall. In this study, shearing stress corresponding to adhesion force per unit area to remove ice from the wall surface and some reagents' contact angles on the wall and ice were measured, varying the wall material and its surface state. Moreover, shearing work to remove ice from the wall surface and surface energies of the wall and ice were calculated by the shearing stress and contact angles, respectively. And adhesion energy at an interface between ice and the wall was also calculated by the calculated surface energies. And then, influence of heat transfer and interfacial phenomena on ice adhesion was discussed to clarify the mechanism of ice adhesion.     

Development of computer program for simulation of an ice bank system operation, Part I: Mathematical modelling

Since the use of standard engineering methods in the process of an ice bank performance evaluation offers neither adequate flexibility nor accuracy, the aim of this research was to provide a powerful tool for an industrial design of an ice storage system allowing to account for the various design parameters and system arrangements over a wide range of time varying operating conditions. In this paper the development of a computer application for the prediction of an ice bank system operation is presented. Static, indirect, cool thermal storage systems with external ice on coil building/melting were considered. The mathematical model was developed by means of energy and mass balance relations for each component of the system and is basically divided into two parts, the model of an ice storage system and the model of a refrigeration unit. Heat transfer processes in an ice silo were modelled by use of empirical correlations while the performance of refrigeration unit components were based on manufacturers data. Programming and application design were made in Fortran 95 language standard. Input of data is enabled through drop down menus and dialog boxes, while the results are presented via figures, diagrams and data (ASCII) files. In addition, to demonstrate the necessity for development of simulation program a case study was performed. Simulation results clearly indicate that no simple engineering methods or rule of thumb principles could be utilised in order to validate performance of an ice bank system properly.     

白细胞介素2(~(125)Ser)在昆虫细胞中的高效表达

目的　高效表达白细胞介素 2 (12 5Ser)。方法　采用新型Bac -to -Bac杆状病毒表达系统 ,以PCR技术扩增了人白细胞介素 2 (12 5Ser)的基因片段 ,将其克隆到转座载体 ,经转座作用将白细胞介素 2 (12 5Ser)基因插入杆状病毒穿梭载体 ,在昆虫细胞中表达。结果　通过免疫印迹实验及CTLL - 2细胞 /MTT法检测 ,表达产物具有人白细胞介素 2的免疫学及生物学活性。经SDS -PAGE电泳 ,薄层扫描分折 ,表达量达到了 2 3.47%。结论　白细胞介素 2 (12 5Ser)在昆虫细胞中获得了高效表达。     

Application of thermal battery in the ice storage air-conditioning system as a subcooler

This article experimentally investigates the thermal performance of a thermal battery used in the ice storage air-conditioning system as a subcooler. The thermal battery utilizes the superior heat transfer characteristics of two-phase closed thermosyphon and eliminates the drawbacks found in convectional energy storage systems. Experimental investigations are first conducted to study the thermal behavior of thermal battery under different charge temperatures (−5 °C to −9 °C) in which water is used as the energy storage material. This study also examines the thermal performance of the subcooled ice storage air conditioner under different cooling loads. Experimental data of temperature variation of water, ice fraction, refrigerant mass flow rate and coefficient of performance (COP) are obtained. The results show that supercooling phenomenon appears in the water and it can be ended when the charge temperature is lower than −6 °C. The system gives 28% more cooling capacity and 8% higher COP by the contribution of the thermal battery used as a subcooler.     

Measurement of thermal conductivity of ice slurry made from solution by transient line heat-source technique (analytical discussion on influence of latent heat of fusion)

We have been studying on ice slurry in a dynamic type ice storage system. The ice slurry has many good characteristics. The ice slurry can be made from a solution. When designing the ice storage system using this ice slurry, thermal conductivity of the ice slurry is essential.When thermal conductivity of the ice slurry made from a solution is measured by a transient line heat-source technique, a measurement value of thermal conductivity is affected by a latent heat of fusion of ice. Therefore, the thermal conductivity measured is apparent thermal conductivity. In this study, influences of Stefan number, initial concentration of the solution, initial solid fraction (initial IPF) and Fourier number on the thermal conductivity was analytically discussed to improve measurement accuracy of the thermal conductivity of ice slurry in the transient line heat-source technique.     

Search for Shorter Portions of the Proline-Rich Antimicrobial Peptide Fragment Bac5(1–25) That Retain Antimicrobial Activity by Blocking Protein Synthesis

The spread of antibiotic-resistant pathogens has boosted the search for new antimicrobial drugs. Proline-rich antimicrobial peptides are promising lead compounds for the development of next-generation antibiotics, given their very low cytotoxicity and their good antimicrobial activity targeting the bacterial ribosome. Bac5(1–25) is an N-terminal fragment of the bovine proline-rich antimicrobial peptide Bac5, whose mode of action has been recently described. In this work we tested a number of Bac5(1–25) fragments, and we characterized their antimicrobial activity against Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella enterica, and Pseudomonas aeruginosa. We evaluated their cytotoxicity toward human cells and their efficacy in inhibiting bacterial protein synthesis. This allowed us to identify some shorter fragments of Bac5(1–25) with a good balance between antibacterial efficacy, protein synthesis inhibition, and ease/cost-effectiveness of synthesis, suitable as lead compounds to develop new antibacterials.     

Suppression of ice adhesion force to cooling wall due to voltage application

For ice storage, one of the authors has previously reported on the ice slurry formed by cooling water–silicone oil mixture with stirring. When the mixture is stirred in a vessel, the oil is charged due to static electricity. If the vessel can attract the charged oil, suppression of ice adhesion force to a cooling wall may be possible. In this study, therefore, a certain voltage was applied to the vessel filled with the mixture with cooling and stirring simultaneously, and water was frozen in the vessel. Then, the ice adhesion force to the cooling vessel wall was measured under a constant apparent adhesion area between the ice and cooling vessel wall. From the measurement results, optimal conditions of the oil viscosity, rotation speed and applied voltage to suppress the ice adhesion force effectively were clarified. Moreover, the factors governing suppression of the ice adhesion force were clarified.     

Study on prevention of ice adhesion to cooling wall due to voltage impression in ice storage—discussion on possibility of attraction of oil to wall

For ice storage, one of authors has studied new ice slurry formed by cooling a water–oil mixture with stirring. When the mixture is stirred in a vessel, oil is charged by static electricity due to friction. If the vessel wall can attract charged oil, prevention of ice adhesion to the wall may be realized. Therefore, in this paper, in order to observe behavior of charged water–oil droplet or mixture in electric field by a high speed camera or video camera, two types of experiments were carried out. One was that the water–oil droplet charged by static electricity was made to fall plumb down between two electrodes with electric field or without electric field, varying the water content of droplet. The other was that a constant voltage was applied on the vessel filled with the water–oil mixture stirred. From experiments, it was confirmed that attracting force between the charged wall (electrode) and charged oil acted.