Insights into the Action Mechanism of the Antimicrobial Peptide Lasioglossin III

Lasioglossin III (LL-III) is a cationic antimicrobial peptide derived from the venom of the eusocial bee Lasioglossum laticeps. LL-III is extremely toxic to both Gram-positive and Gram-negative bacteria, and it exhibits antifungal as well as antitumor activity. Moreover, it shows low hemolytic activity, and it has almost no toxic effects on eukaryotic cells. However, the molecular basis of the LL-III mechanism of action is still unclear. In this study, we characterized by means of calorimetric (DSC) and spectroscopic (CD, fluorescence) techniques its interaction with liposomes composed of a mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-rac-phosphoglycerol (POPG) lipids as a model of the negatively charged membrane of pathogens. For comparison, the interaction of LL-III with the uncharged POPC liposomes was also studied. Our data showed that LL-III preferentially interacted with anionic lipids in the POPC/POPG liposomes and induces the formation of lipid domains. Furthermore, the leakage experiments showed that the peptide could permeabilize the membrane. Interestingly, our DSC results showed that the peptide-membrane interaction occurs in a non-disruptive manner, indicating an intracellular targeting mode of action for this peptide. Consistent with this hypothesis, our gel-retardation assay experiments showed that LL-III could interact with plasmid DNA, suggesting a possible intracellular target.     

The Histidine Phosphocarrier Kinase/Phosphorylase from Bacillus Subtilis Is an Oligomer in Solution with a High Thermal Stability

The histidine phosphocarrier protein (HPr) kinase/phosphorylase (HPrK/P) modulates the phosphorylation state of the HPr protein, and it is involved in the use of carbon sources by Gram-positive bacteria. Its X-ray structure, as concluded from crystals of proteins from several species, is a hexamer; however, there are no studies about its conformational stability, and how its structure is modified by the pH. We have embarked on the conformational characterization of HPrK/P of Bacillus subtilis (bsHPrK/P) in solution by using several spectroscopic (namely, fluorescence and circular dichroism (CD)) and biophysical techniques (namely, small-angle X-ray-scattering (SAXS) and dynamic light-scattering (DLS)). bsHPrK/P was mainly a hexamer in solution at pH 7.0, in the presence of phosphate. The protein had a high conformational stability, with an apparent thermal denaturation midpoint of ~70 °C, at pH 7.0, as monitored by fluorescence and CD. The protein was very pH-sensitive, precipitated between pH 3.5 and 6.5; below pH 3.5, it had a molten-globule-like conformation; and it acquired a native-like structure in a narrow pH range (between pH 7.0 and 8.0). Guanidinium hydrochloride (GdmCl) denaturation occurred through an oligomeric intermediate. On the other hand, urea denaturation occurred as a single transition, in the range of concentrations between 1.8 and 18 µM, as detected by far-UV CD and fluorescence.     

GRAIN SHAPE EFFECT IN SUPERPLASTIC DEFORMATION

The method controlling grain shape in TMT processing and the effect of grain shape on char-acteristic parameters in superplastic deformation were discussed.The accommodation velocityof grahl boundary sliding,which is the dominant mechanism in superplastic deformation,andthe contribution of each mechanism to the total strain,as influenced by grain shape,were ana-lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Thenan analysis was made about the effect of grain shape on the region transition strain rate sothat a new concept,critical aspect for superplasticity,was worked out.These predictions werecompared with the measured results in an Al-Zn-Mg alloy.     

基于分水岭和区域合并的图像分割算法*

提出一种应用分水岭与区域合并相结合的图像分割算法.本方法首先利用数学形态学分水岭算法对图像进行分割,然后对分割后的图像进行相似区域合并,以减少分水岭方法产生的过分割现象,从而得到较好的分割效果.     

轴流式转轮三元粘性流动数值计算

为进一步提高轴流式转轮的设计精度与性能,采用时均Navier-Stokes控制方程,标准k-ε湍流模型及SIMPLEC算法,对一轴流定浆式水轮机转轮内三元粘性流动进行了数值模拟。提出了水力损失计算方法,获得了转轮的预测效率。分析了转轮内部流场分布规律,建立了叶片表面压力在包角范围内的变化曲线,有助于认识转轮内真实流动现象,为改善设计提供可视化数据支持。     

基于三维特征向量的非侵入式电热负荷细分算法

非侵入式负荷监测分解（NILMD）技术是当前居民用能服务深化提升和电力供需互动的重要数据获取手段,然而当前工程上应用广泛的事件驱动型NILMD技术一直无法准确细化分解电热负荷。针对这一问题,文中提出了一种基于三维特征向量的典型电热负荷细化分解算法。首先,基于有功、无功功率和电流谐波等电气负荷特征采用事件检测方法提取电热事件,在有功功率的基础上,引入运行时长、频繁启停次数等非电气负荷特征共同构建三维特征向量电器模型。然后,采用序贯覆盖法设计典型电热负荷细化分解命题学习规则和细化分解算法。最后,基于实证实验数据进行分解验证,发现4种典型电热负荷的细化分解准确率超过85%。实验结果表明,文中所提典型电热负荷细化分解算法有效地提高了4种典型电热负荷分解的准确率。     

液压-齿轮-齿条圆弧分型抽芯压铸模设计

给出了龙头体液压-齿轮-齿条圆弧分型抽芯压铸模实用结构，论述了模具的浇铸系统、结构特点和工作原理。该模具采用扇形龄轮-齿条机构实现龙头体铸件的侧向圆弧分型抽芯，同时通过相应的两套斜销滑块机构分别实现龙头体铸件另外两个方向的侧向分型抽芯。     

填隙Ti2Ni相形成条件的模式识别分析

在多维键参数空间中对填隙Ti_2Ni相化合物的形成条件做模式识别分析,由于前过渡金属原子组成的八面体空穴中填入C,N.O原子使Ti_2Ni结构稳定化,此结构的分布区扩大,邻近的Al_2Cu,MoSi_2结构分布区减小。     

金相显微镜三维自动平台

运用现代计算机信息处理技术和自动控制技术，成功地对一台国产显微镜和一台进口显微镜的载物台进行了自动化改造，实现了X、Y方向自动移动和Z方向自动聚焦。本方案改造加工工作小，成本低，不破坏原有显微镜结构，同时还保留了传统的手动调节方法，使用户更容易接受。同时，系统控制软件还中嵌了软件可编程技术，从而简化了操作过程，明显减轻了劳动强度。本系统符合我国国情，是进口设备优良的替代品。     

金属薄板的精密剪切

详细地叙述了精密分条圆盘刀片在金属薄板精密剪切中的重要性,并介绍了圆盘刀片的正确使用方法.文中的一些数据和用刀的观念对国内快速发展的金属薄板的加工行业有参考价值.