Zapotin,a Polymethoxyflavone,with Potential Therapeutic Attributes

The use of plants as traditional medicines is common and has prevailed in many different cultures over time. Polymethoxyflavones (PMFs) are natural polyphenols from the group of flavonoids. Zapotin, a member of the PMFs, is found mainly in citrus plants and is almost exclusively limited to their peels. The chemical structure of zapotin has been questioned from the very beginning, since the structure of flavonoids with a single oxygen atom in the C2′ position is extremely rare in the plant kingdom. To clarify this, the structural determination and bio-inspired synthesis of zapotin are discussed in detail in this review. Due to the broad biological potential of PMFs, the complication in the isolation process and characterization of PMFs, as well as their purification, have been estimated by adapting various chromatographic methods. According to available data from the literature, zapotin may be a promising curative agent with extensive biological activities, especially as a chemopreventive factor. Apart from that, zapotin acts as an antidepressant-like, anticancer, antifungal, and antioxidant agent. Finally, accessible studies about zapotin metabolism (absorption, distribution, metabolism, excretion, and toxicity) underline its potential in use as a therapeutic substance.     

Cationic Phenosafranin Photosensitizers Based on Polyhedral Oligomeric Silsesquioxanes for Inactivation of Gram-Positive and Gram-Negative Bacteria

The high photodynamic effect of the Newman strain of the S. aureus and of clinical strains of S. aureus MRSA 12673 and E. coli 12519 are observed for new cationic light-activated phenosafranin polyhedral oligomeric silsesquioxane (POSS) conjugates in vitro. Killing of bacteria was achieved at low concentrations of silsesquioxanes (0.38 µM) after light irradiation (λ_{em. max} = 522 nm, 10.6 mW/cm²) for 5 min. Water-soluble POSS-photosensitizers are synthesized by chemically coupling a phenosafranin dye (PSF) (3,7-diamino-5-phenylphenazine chloride) to an inorganic silsesquioxane cage activated by attachment of succinic anhydride rings. The chemical structure of conjugates is confirmed by ¹H, ¹³C NMR, HRMS, IR, fluorescence spectroscopy and UV-VIS analyzes. The APDI and daunorubicin (DAU) synergy is investigated for POSSPSFDAU conjugates. Confocal microscopy experiments indicate a site of intracellular accumulation of the POSSPSF, whereas iBuPOSSPSF and POSSPSFDAU accumulate in the cell wall or cell membrane. Results from the TEM study show ruptured S. aureus cells with leaking cytosolic mass and distorted cells of E. coli. Bacterial cells are eradicated by ROS produced upon irradiation of the covalent conjugates that can kill the bacteria by destruction of cellular membranes, intracellular proteins and DNA through the oxidative damage of bacteria.     

On the Dependence of Prion and Amyloid Structure on the Folding Environment

Currently available analyses of amyloid proteins reveal the necessity of the existence of radical structural changes in amyloid transformation processes. The analysis carried out in this paper based on the model called fuzzy oil drop (FOD) and its modified form (FOD-M) allows quantifying the role of the environment, particularly including the aquatic environment. The starting point and basis for the present presentation is the statement about the presence of two fundamentally different methods of organizing polypeptides into ordered conformations—globular proteins and amyloids. The present study shows the source of the differences between these two paths resulting from the specificity of the external force field coming from the environment, including the aquatic and hydrophobic one. The water environment expressed in the fuzzy oil drop model using the 3D Gauss function directs the folding process towards the construction of a micelle-like system with a hydrophobic core in the central part and the exposure of polarity on the surface. The hydrophobicity distribution of membrane proteins has the opposite characteristic: Exposure of hydrophobicity at the surface of the membrane protein with an often polar center (as in the case of ion channels) is expected. The structure of most proteins is influenced by a more or less modified force field generated by water through the appropriate presence of a non-polar (membrane-like) environment. The determination of the proportion of a factor different from polar water enables the assessment of the protein status by indicating factors favoring the structure it represents.     

基于惩罚模型的K-确认共识机制

区块链作为一门新兴技术,因其具有去中心化、数据信息的不可篡改性以及用户信息的高度隐私性等特点,已经成为了研究和应用场景开发的热点.然而随着区块链技术的发展,作为区块链系统的核心技术-共识机制所产生的效率远远满足不了当今的发展步伐.针对上述问题,通过分析当前区块链共识机制的优化方案,首次提出了将确保交易正确无误的共识任务...     

硫酸型镀铟电极过程动力学初探

过去用电化学方法对硫酸型镀铟工艺、作用机理研究较少.采用循环伏安、线性电位扫描和交流阻抗等电化学方法,研究了硫酸型镀铟中的阴极反应机理.结果表明:该体系内铟电沉积的最佳pH值为2～3,最佳温度为35～45℃;该阴极过程中存在前置化学反应和随后两个不可逆电化学反应,其中第一个电化学反应是控制步骤,其阴极过程电极反应标准常数为8.188×10-10cm/s.     

不完备契约下的企业控制权对金融契约效率的影响

构造了不完备金融契约环境下,企业控制权对金融契约效率影响的博弈论模型。在加进控制权因素后,影响金融契约效率的因素不仅仅是投资者受益、管理者的努力水平、管理者的私人福利等,更重要的是金融契约的不完备程度.这个因素对金融契约效率的影响是通过对投资者、管理者努力水平和管理者的私人福利的影响实现的。可以利用金融契约的不完备性讨论融资行为影响的传导机制。     

多股射流瓦斯燃烧器湍流扩散火焰尺度的实验研究

用火焰图像分析方法,对一种多股射流燃烧器燃烧富含氢气的瓦斯产生的湍流扩散火焰的尺度进行了实验研究,研究了燃烧器结构参数和操作参数对火焰长度和长宽比等尺度特性的影响规律。结果表明,火焰长度随燃烧器喷孔总面积的增大和燃气流量的增大而增大,随助燃空气过剩系数的增大而减小;火焰长度和长宽比随上层喷孔位置角的增大而减小。同时发现,瓦斯中氢气含量对火焰尺度影响较大,随着氢气含量增大,火焰长度和长宽比都明显减小。     

采用激光跟踪仪测量飞机外形

利用激光跟踪仪测量空间点坐标的原理,通过“转站”建立飞机坐标系,采集飞机外形坐标点云,处理数据并建立数学模型。     

300 MW等级锅炉变工况低负荷稳燃能力数值模拟与预测

采用数值模拟软测量技术,在保证锅炉燃烧稳定和炉内温度较高水平的条件下,预测300 MW等级锅炉在实际运行中可降低到25%负荷稳定燃烧,并经过现场低负荷稳燃实验对结果进行验证。针对一次风速调整、磨煤机投运方式调整和配风方式及运行氧量调整三种方式对低负荷稳燃能力的影响进行分析,结果表明:在降负荷过程中调平一次风速偏差并适当降低一次风速,投运相邻层燃烧器,关小周界风,适当降低二次风量的同时适当降低运行氧量有利于提高低负荷稳燃特性。