Engineering reactions in crystalline solids: predicting photochemical decarbonylation from calculated thermochemical parameters

A detailed thermochemical analysis of the alpha-cleavage and decarbonylation reactions of acetone and several ketodiesters was carried out with the B3LYP/6-31G* density functional method. The heats of formation of several ground-state ketones and radicals were calculated at 298 K to determine bond dissociation energies (BDE) and radical stabilization energies (RSE) as a function of substituents. Results show that the radical-stabilizing abilities of the ketone substituents play a very important role on the thermodynamics of the alpha-cleavage and decarbonylation steps. An excellent correlation between calculated values and previous experimental observations suggests that photochemical alpha-cleavage and decarbonylation in crystals should be predictable from knowledge of excitation energies and the RSE of the substituent.     

Purines, pyrimidines, and related fused systems. 20. Heterocyclizations of 6-alkynyl-1,3-dimethyllumazines. Synthesis of pyrrole and thiophene analogs of some natural pteridines

Sonogashira cross-coupling of 6-chloro-1,3-dimethyllumazine with terminal alkynes gave 6-alkynyl derivatives in good yields. Oxidative amination of the latter with primary alkylamines was accompanied by the pyrrole-ring closure to form 1-R"-2-R-6,8-dimethylpyrrolo[3,2-g]pteridine-5,7(6H,8H)-diones. The addition of bromine to 6-alkynyllumazines afforded the corresponding dibromoalkenes whose treatment with sodium trithiocarbonate gave rise to 2-R-6,8-dimethylthieno[3,2-g]pteridine-5,7(6H,8H)-diones. The latter compounds are close analogs of the metabolite of molybdenum cofactor (molybdopterine).     

Inhibitory Effects of Myriocin on Non-Enzymatic Glycation of Bovine Serum Albumin

Advanced glycation end products (AGEs) are the compounds produced by non-enzymatic glycation of proteins, which are involved in diabetic-related complications. To investigate the potential anti-glycation activity of Myriocin (Myr), a fungal metabolite of Cordyceps, the effect of Myr on the formation of AGEs resulted from the glycation of bovine serum albumin (BSA) and the interaction between Myr and BSA were studied by multiple spectroscopic techniques and computational simulations. We found that Myr inhibited the formation of AGEs at the end stage of glycation reaction and exhibited strong anti-fibrillation activity. Spectroscopic analysis revealed that Myr quenched the fluorescence of BSA in a static process, with the possible formation of a complex (approximate molar ratio of 1:1). The binding between BSA and Myr mainly depended on van der Waals interaction, hydrophobic interactions and hydrogen bond. The synchronous fluorescence and UV-visible (UV-vis) spectra results indicated that the conformation of BSA altered in the presence of Myr. The fluorescent probe displacement experiments and molecular docking suggested that Myr primarily bound to binding site 1 (subdomain IIA) of BSA. These findings demonstrate that Myr is a potential anti-glycation agent and provide a theoretical basis for the further functional research of Myr in the prevention and treatment of AGEs-related diseases.     

神光-Ⅲ主机装置成功实现60 TW/180 kJ三倍频激光输出

2015年9月15日,由中国工程物理研究院激光聚变研究中心承担研制的神光-Ⅲ主机装置成功完成了48束激光三倍频180 kJ/3 ns、峰值功率60 TW的输出测试实验,标志着神光-Ⅲ主机装置已全面建成并达到设计指标,成为现有输出能力世界排名第二、亚洲排名第一的惯性约束聚变激光驱动器。神光-Ⅲ主机装置可输出48束阵列化的大口径高功率脉冲激光（分为6个束组,每个束组为一个42的光束阵列）,主要由前端、预放、主放、测量与光束控制、靶场、计算机集中控制等六大系统组成。神光-Ⅲ主机装置的研制,凝集了我国在光学、激光、脉冲功率、精密机械、快电子学、自动控制、化学清洗、超精密加工等多个学科领域的顶尖技术成就,堪称中国光学工程界的奇迹。神光-Ⅲ主机装置采用腔内四程放大+变口径90翻转U型反转器+助推三程放大的总体构型,在未使用大口径隔离组件的条件下,采用焦斑控制、精密准直、锥管镜面空间滤波及杂散光管理等技术措施,实现了基频光十万倍增益、10 kJ量级输出状态下的自激振荡抑制与反激光规避,在系统具备50%以上透过率的前提下确保了装置的运行安全,大大提高了装置的性价比。神光-Ⅲ主机装置的建设过程中攻克了高精度种子光源、高品质激光束的预放大、精密同步、辐射定标损伤检测、全光路精密波前校正、甚多束光路自动准直、自动化靶瞄准定位、计算机集中控制、高效谐波转换、一搁准精密安装、超精密光学加工、缺陷控制损伤阈值提升等多项光学工程技术难关,确保了装置具备优秀的技术指标性能。神光-Ⅲ主机装置打破了激光系统串行调试的规律,基于基准体系技术,通过不同束组间的错级并行,实现总体集成工作的满负荷运转,确保了装置建设的总体进度和集成效率。装置从第一个光机模块进场到基本完成集成调试,用时仅四年半,创造了又一个中国速度。在工程建设过程中以自主研发的传输放大动力学设计软件、激光泵浦动力学软件、杂散光树叉追迹软件等为基础,融合了部分光学设计商用软件,构建了覆盖光学、结构、电气、控制等多个学科的高功率激光装置数字化设计平台,基本实现了装置设计的全面数字化。工程建设过程中形成的质量、安全、进度控制体系保证了工程顺利进行。神光-Ⅲ主机装置的全面建成,标志着我国在大型激光驱动器方面的总体设计、总体集成、精密装校、加工制造、光学检测、关键技术等核心能力实现了体系化发展与成熟,面向更大规模的激光驱动器研制的光学工程体系已基本形成。     

The Antibacterial Activity Mode of Action of Plantaricin YKX against Staphylococcus aureus

We aimed to evaluate the inhibitory effect and mechanism of plantaricin YKX on S. aureus. The mode of action of plantaricin YKX against the cells of S. aureus indicated that plantaricin YKX was able to cause the leakage of cellular content and damage the structure of the cell membranes. Additionally, plantaricin YKX was also able to inhibit the formation of S. aureus biofilms. As the concentration of plantaricin YKX reached 3/4 MIC, the percentage of biofilm formation inhibition was over 50%. Fluorescent dye labeling combined with fluorescence microscopy confirmed the results. Finally, the effect of plantaricin YKX on the AI-2/LuxS QS system was investigated. Molecular docking predicted that the binding energy of AI-2 and plantaricin YKX was −4.7 kcal/mol and the binding energy of bacteriocin and luxS protein was −183.701 kcal/mol. The expression of the luxS gene increased significantly after being cocultured with plantaricin YKX, suggesting that plantaricin YKX can affect the QS system of S. aureus.     

Coulomb forces impacts on nanomaterial transportation within porous tank with lid walls

Journal of Thermal Analysis and Calorimetry - Electrical sensor has been considered in the current attempt. Combination of buoyancy, electric and radiative forces has been included in the governing...     

Tuning the Reactivity of a Substrate for SNAP-Tag Expands Its Application for Recognition-Driven DNA-Protein Conjugation

Recognition-driven modification has been emerging as a novel approach to modifying biomolecular targets of interest site-specifically and efficiently. To this end, protein modular adaptors (MAs) are the ideal reaction model for recognition-driven modification of DNA as they consist of both a sequence-specific DNA-binding domain (DBD) and a self-ligating protein-tag. Coupling DNA recognition by DBD and the chemoselective reaction of the protein tag could provide a highly efficient sequence-specific reaction. However, combining an MA consisting of a reactive protein-tag and its substrate, for example, SNAP-tag and benzyl guanine (BG), revealed rather nonselective reaction with DNA. Therefore new substrates of SNAP-tag have been designed to realize sequence-selective rapid crosslinking reactions of MAs with SNAP-tag. The reactions of substrates with SNAP-tag were verified by kinetic analyses to enable the sequence-selective crosslinking reaction of MA. The new substrate enables the distinctive orthogonality of SNAP-tag against CLIP-tag to achieve orthogonal DNA-protein crosslinking by six unique MAs.