基于格子玻尔兹曼的两相闭式环路热虹吸研究

两相闭式环路热虹吸(CLTPT)形成定向循环的动力来源是重力在蒸发器和冷凝器之间形成的压力差。本文通过修改Gong-Cheng相变LBM模型中重力项计算方式,成功模拟了CLTPT在沸腾和凝结相变共同作用下产生的自驱动现象,揭示了不同充液率下的多种两相流型的存在。发现对于本文设计的热虹吸管结构,在初始状态液相覆盖全部蒸发段的前提下,充液率越小,CLTPT的周期性越复杂,越难达到稳定运行状态,系统自循环时均质量流量更小,同时蒸发段时均温度更低。     

基于IABC-SVR算法的拉曼光谱定量分析山羊血清蛋白含量

提出了一种基于拉曼光谱和改进人工蜂群算法优化支持向量机回归(IABC-SVR)算法快速定量检测山羊血清蛋白含量的方法.传统人工蜂群算法在数据区域规模较大时,收敛速度逐渐减慢,出现效率低、精准度下降、局部最优解概率高等问题.所提出的算法解决了这些问题,使算法在进化前期避免陷入局部最优解,在进化中后期能够保持解的全局搜索能...     

Equilibrium folding and unfolding dynamics to reveal detailed free energy landscape of src SH3 protein by magnetic tweezers

Src SH3 protein domain is a typical two-state protein which has been confirmed by research of denaturant-induced unfolding dynamics. Force spectroscopy experiments by optical tweezers and atomic force microscopy have measured the force-dependent unfolding rates with different kinds of pulling geometry. However, the equilibrium folding and unfolding dynamics at constant forces has not been reported. Here, using stable magnetic tweezers, we performed equilibrium folding and unfolding dynamic measurement and force-jump measurement of src SH3 domain with tethering points at its N-and C-termini. From the obtained force-dependent transition rates, a detailed two-state free energy landscape of src SH3 protein is constructed with quantitative information of folding free energy, transition state barrier height and position,which exemplifies the capability of magnetic tweezers to study protein folding and unfolding dynamics.     

High-intensity ultrasound improved the physicochemical and gelling properties of Litopenaeus vannamei myofibrillar protein

The effects of high-intensity ultrasound on the physicochemical and gelling properties of Litopenaeus vannamei (L. vannamei) myofibrillar protein (MP) were investigated. MP solutions were subjected to ultrasound treatment (power 100 W, 300 W, and 500 W). It was found that the carbonyl and free amino contents of MP increased significantly with increasing ultrasound power, accompanied by enhanced emulsification properties. The increase of free radical and carbonyl content indicated that ultrasound induced the oxidation of MP. With the increase of ultrasound power, it was found that the total sulfhydryl content of the shrimp MP decreased, but the surface hydrophobicity increased significantly, which might be closely related to the conformational changes of MP. Meanwhile, a significant increase of β-sheet but a decrease of α-helix in the secondary structure of MP was observed with increasing ultrasound power, indicating that ultrasound treatment induced the stretching and flexibility of MP molecules. SDS-PAGE showed that L. vannamei MP consisted of myosin heavy chain, actin, myosin light chain, paramyosin and tropomyosin. Ultrasound treatment could lead to some degree of oxidative aggregation of MP. The results of rheological properties indicated that ultrasound treatment enhanced the viscoelasticity of MP and further improved the gel strength of MP gel. This study can provide a theoretical basis for the functional modification of shrimp MP and the processing of its surimi products.     

Effects of ultrasonic–microwave combination treatment on the physicochemical,structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.     

鱼糜漂洗水中可溶蛋白的回收技术

对鱼糜漂洗水中可溶蛋白的综合回收技术情况进行了相关介绍, 主要包括絮凝沉淀法、等电点沉淀法、膜分离法、电阻加热法等, 这些技术的使用不仅实现了蛋白资源的再利用, 而且也减少了对环境的污染.     

饲料中补充晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能的影响

饲料中添加30%鱼粉为对照组饲料和6组试验饲料(分别替代对照组中16.67%、33.33%和50.00%的鱼粉,同一鱼粉替代水平的2组分别添加晶体蛋氨酸和羟基蛋氨酸钙,使其蛋氨酸含量与对照组一致)喂养罗氏沼虾(初始体重为(0.29±0.04) g )10周,研究不同鱼粉替代水平下,分别添加晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能和血清生化指标的影响.结果表明：复合蛋白源替代对照组16.67%鱼粉并补充羟基蛋氨酸钙组的增重率、特定生长率、蛋白质效率和饲料系数同对照组无显著差异(P>0.05);同一鱼粉替代水平下,羟基蛋氨酸钙组的增重率、特定生长率和蛋白质效率均显著高于晶体蛋氨酸组(P<0.05).血清生化组成的分析结果表明：血清总蛋白含量各处理组之间差异显著(P<0.05),对照组血清谷草转氨酶和谷丙转氨酶活力显著低于其他各组(P<0.05),其中同一替代水平下,饲料中添加羟基蛋氨酸钙组谷草转氨酶和谷丙转氨酶活力低于添加晶体蛋氨酸组.由此可见,与晶体蛋氨酸相比,羟基蛋氨酸钙能更有效提高罗氏沼虾生长性能和饲料利用效率.     

浙江萧山、舟山和福建集美臭鼩血红蛋白、血清蛋白电泳比较研究

本文用血红蛋白的薄层等电聚焦技术对浙江萧山、舟山和福建集美的三地臭鼩进行比较,结果显示:大陆(萧山与集美)和海岛(舟山)之间的带谱存在差异.大陆有6条区带,海岛的带谱变化较大,存在四种不同类型.用血清蛋白的SDS-聚丙烯酰胺凝胶电泳技术和血清蛋白的薄层等电聚焦技术对上述三地臭鼩的分析表明:海岛个体血清蛋白的成份和在血液中相对含量较大陆为少,而大陆萧山和集美的血清蛋白在血液中的相对含量和成份亦略有不同.     

反应扩散系统中波传播的锁频现象

在空间延展系统中,当增强外部光强时,作者观察到波传播的N∶N-1(N≥2)锁频现象.此现象是在光敏BZ反应实验中观察到的.通过构建一个映射函数,发现在波周期和外部光强的关系中存在魔鬼阶梯,并且此阶梯与实验数据相吻合.     

Membrane Organization and Dynamics of the G-Protein-Coupled Serotonin<Subscript>1A</Subscript> Receptor Monitored Using Fluorescence-Based Approaches

The G-protein-coupled receptor (GPCR) superfamily represents one of the largest classes of molecules involved in signal transduction across the plasma membrane. Fluorescence-based approaches have provided valuable insights into GPCR functions such as receptor–receptor and receptor–ligand interactions, real-time assessment of signal transduction, receptor dynamics on the plasma membrane, and intracellular trafficking of receptors. This has largely been possible with the use of fluorescent probes such as the green fluorescent protein (GFP) from the jellyfish Aequoria victoria and its variants. We discuss the potential of fluorescence-based approaches in providing novel information on the membrane organization and dynamics of the G-protein-coupled serotonin_1A receptor tagged to the enhanced yellow fluorescent protein (EYFP). These authors contributed equally to the work.