A new precursor for organo-osmium complexes

The use of potassium osmate, K₂[OsO₂(OH)₄], as a precursor for some cyclopentadienyl-osmium complexes is described. The X-ray structures of OsBr(PPh₃)₂Cp, OsCl(dppe)Cp and OsX(dppe)Cp^∗ (X = Cl, Br) are reported.     

虎杖象甲培植真菌营养特性及对菌丝附属物形成的影响

虎杖象甲培植共生真菌形成的共生体系是植菌昆虫菌业中的典型代表。共生真菌Penicillium herquei如何向虎杖象甲Euops chinensis提供营养尚未明确。本研究发现共生真菌P. herquei的菌丝表面存在大量瘤状凸起物及由凸起物衍生的附属丝等特化结构,该结构可能为虎杖象甲提供营养;对共生真菌的营养研究表明,共生真菌能高效利用山梨醇、蔗糖、海藻糖、葡萄糖等单糖或双糖,以及酪氨酸、甘氨酸、谷氨酰胺等昆虫非必须氨基酸,同时在高碳和最适碳源条件下有利于菌丝特化附属物的产生。研究结果不仅提供了植菌卷叶象甲菌业中共生真菌在营养方面的适应性进化证据,而且为进一步揭示共生真菌适应卷叶象甲的营养机制奠定了基础。     

Understanding Molecular Structures of Buried Interfaces in Halide Perovskite Photovoltaic Devices Nondestructively with Sub‐Monolayer Sensitivity Using Sum Frequency Generation Vibrational Spectroscopy

As performance of halide perovskite devices progresses, the device structure becomes more complex with more layers. Molecular interfacial structures between different layers play an increasingly important role in determining the overall performance in a halide perovskite device. However, current understanding of such interfacial structures at a molecular level nondestructively is limited, partially due to a lack of appropriate analytical tools to probe buried interfacial molecular structures in situ. Here, sum frequency generation (SFG) vibrational spectroscopy, a state‐of‐the‐art nonlinear interface sensitive spectroscopy, is introduced to the halide perovskite research community and is presented as a powerful tool to understand molecule behavior at buried halide perovskite interfaces in situ. It is found that interfacial molecular orientations revealed by SFG can be directly correlated to halide perovskite device performance. Here how SFG can examine molecular structures (e.g., orientations) at the perovskite/hole transporting layer and perovskite/electron transporting layer interfaces is discussed. This will promote the use of SFG to investigate molecular structures of buried interfaces in various halide perovskite materials and devices in situ nondestructively with a sub‐monolayer interface sensitivity. Such research will help to elucidate structure–function relationships of buried interfaces, aiding in the rational design/development of halide perovskite materials/devices with improved performance.     

2D Metal Zn Nanostructure Electrodes for High‐Performance Zn Ion Supercapacitors

Recent supercapacitors show a high power density with long‐term cycle life time in energy‐powering applications. A supercapacitor based on a single metal electrode accompanying multivalent cations, multiple charging/discharging kinetics, and high electrical conductivity is a promising energy‐storing system that replaces conventionally used oxide and sulfide materials. Here, a hierarchically nanostructured 2D‐Zn metal electrode‐ion supercapacitor (ZIC) is reported which significantly enhances the ion diffusion ability and overall energy storage performance. Those nanostructures can also be successfully plated on various flat‐type and fiber‐type current collectors by a controlled electroplating method. The ZIC exhibits excellent pseudocapacitive performance with a high energy density of 208 W h kg^?1 and a power density from 500 W kg^?1, which are significantly higher than those of previously reported supercapacitors with oxide and sulfide materials. Furthermore, the fiber‐type ZIC also shows high energy‐storing performance, outstanding mechanical flexibility, and waterproof characteristics, without any significant capacitance degradation during bending tests. These results highlight the promising possibility of nanostructured 2D Zn metal electrodes with the controlled electroplating method for future energy storage applications.     

Separating distinct structures of multiple macromolecular assemblies from cryo-EM projections

Single particle analysis for structure determination in cryo-electron microscopy is traditionally applied to samples purified to near homogeneity as current reconstruction algorithms are not designed to handle heterogeneous mixtures of structures from many distinct macromolecular complexes. We extend on long established methods and demonstrate that relating two-dimensional projection images by their common lines in a graphical framework is sufficient for partitioning distinct protein and multiprotein complexes within the same data set. The feasibility of this approach is first demonstrated on a large set of synthetic reprojections from 35 unique macromolecular structures spanning a mass range of hundreds to thousands of kilodaltons. We then apply our algorithm on cryo-EM data collected from a mixture of five protein complexes and use existing methods to solve multiple three-dimensional structures ab initio. Incorporating methods to sort single particle cryo-EM data from extremely heterogeneous mixtures will alleviate the need for stringent purification and pave the way toward investigation of samples containing many unique structures.     

Ligand design,synthesis and biological anti-HCV evaluations for genotypes 1b and 4a of certain 4-(3- & 4-[3-(3,5-dibromo-4-hydroxyphenyl)-propylamino]phenyl) butyric acids and 3-(3,5-dibromo-4-hydroxyphenyl)-propylamino-acetamidobenzoic acid esters

4-(4-[N-1-carboxy-3-(3,5-dibromo-4-hydroxyphenyl)-3-oxo-propylamino]phenyl)-4-oxo-butyric acid (V), 4-(3- & 4-[N-1-carboxy-3-(3,5-dibromo-4-hydroxyphenyl)-3-oxo-propylaminophenyl]-2-aryl-4-oxo-butyric acids (Xa–e) and 4-(2-alkyl-2-[N-3-(3,5-dibromo-4-hydroxyphenyl)-1-carboxy-3-oxo-propylamino]acetamido) benzoate esters (XVa–e) were designed, synthesized and biologically evaluated as anti-HCV for genotypes 1b and 4a. The design was based on their docking scores with HCV NS3/4A protease-binding site of the genotype 1b (1W3C), which is conserved in the genotype 4a structure. The docking scores predicted that most of these molecules have higher affinity to the HCV NS3/4A enzyme more than Indoline lead. These compounds were synthesized and evaluated for their cytopathic inhibitory activity against RAW HCV cell cultures of genotype 4a and also examined against Huh 5–2 HCV cell culture of genotype 1b, utilizing Luciferase and MTS assays. Compounds Xa and Xb have 95 and 80% of the activity of Ribavirin against genotype 4a and compounds XVa, XVb and XVd exerted high percentage inhibitory activity against genotype 1b equal 87.7, 84.3 and 82.8%, respectively, with low EC₅₀ doses.     

Local Treatment of Murine Tumors by Electric Direct Current

Low-level direct current (0.2–1.8 mA) was demonstrated to be an antitumor agent on two different murine tumor models (fibrosarcoma Sa-1 and melanoma B-16), and has been suggested for regional cancer treatment. Its antitumor effect was achieved by introduction of single or multiple–array needle electrodes (Pt-Ir alloy) in the tumor and (an)other electrode(s) subcutaneously in its vicinity. The electrode inserted in the tumor was made anodic (anodic electrotherapy, ET) or cathodic (cathodic ET). In control groups, animals were subjected to exactly the same procedures with needle electrodes inserted at usual sites without current. In single-stimulus ET performed after the tumors have reached approximately 50 mm3 in volume with 0.2, 0.6, and 1.O mA for 30, 60, and 90 min, cathodic ET exhibited better antitumor effect than anodic ET. In both cases and at all ET durations, the antitumor effect depended proportionally on the current level applied. The antitumor effect was evaluated by following tumor growth and by microscopic estimation of the necrotization of the tumor area immediately after ET, and 24, 48, and 72 h posttreatment.

Necrotization produced by cathodic ET was observed to be immediate and extensive whereas anodic ET resulted in increased necrotization only at 24 h posttreatment. In both cases the extent of necrosis was significantly higher than in control and was centrally located (site of electrode), whereas in controls it was sporadic, distributed randomly over the whole tumor area. When current was delivered via multiple–array electrode ET, the antitumor effect was slightly better in cathodic ET compared to single-electrode ET. Employing cathodic multiple-array electrode ET and using higher currents, i.e., 1.0, 1.4, and 1.8 mA in melanoma B-16, 20% and 40% cures were achieved by 1.4 and 1.8 mA single-shot ET of 1 h duration, respectively, whereas in fibrosarcoma Sa-1 no cures were accomplished. In general, different susceptibility of the two tumor models to ET was noticeable. Comparing tumor growth and necrotization after the application of direct current (0.6 mA) and alternating current (0.0 mA mean, 0.6 mA RMS), it appeared that alternating current had no impact either on necrotization of tumor tissue or on tumor growth. ET was performed on normal tissues as well. In subcutaneous tissue, thigh muscle, and liver of healthy mice immediately after 1 h of treatment using 0.6 mA in both cathodic and anodic modes, local necrotization at the site of electrode insertion was evident, with signs of acute inflammation in the vicinity. In anodic ET, vacuolization around the electrode was noticed.     

Comparing methods for metabolic network analysis and an application to metabolic engineering

Bioinformatics tools have facilitated the reconstruction and analysis of cellular metabolism of various organisms based on information encoded in their genomes. Characterization of cellular metabolism is useful to understand the phenotypic capabilities of these organisms. It has been done quantitatively through the analysis of pathway operations. There are several in silico approaches for analyzing metabolic networks, including structural and stoichiometric analysis, metabolic flux analysis, metabolic control analysis, and several kinetic modeling based analyses. They can serve as a virtual laboratory to give insights into basic principles of cellular functions. This article summarizes the progress and advances in software and algorithm development for metabolic network analysis, along with their applications relevant to cellular physiology, and metabolic engineering with an emphasis on microbial strain optimization. Moreover, it provides a detailed comparative analysis of existing approaches under different categories.     

Temperature‐dependent conformational change affecting Tyr11 and sweetness loops of brazzein

The sweet protein brazzein, a member of the Csβα fold family, contains four disulfide bonds that lend a high degree of thermal and pH stability to its structure. Nevertheless, a variable temperature study has revealed that the protein undergoes a local, reversible conformational change between 37 and 3°C with a midpoint about 27°C that changes the orientations and side‐chain hydrogen bond partners of Tyr8 and Tyr11. To test the functional significance of this effect, we used NMR saturation transfer to investigate the interaction between brazzein and the amino terminal domain of the sweet receptor subunit T1R2; the results showed a stronger interaction at 7°C than at 37°C. Thus the low temperature conformation, which alters the orientations of two loops known to be critical for the sweetness of brazzein, may represent the bound state of brazzein in the complex with the human sweet receptor. Proteins 2013; © 2012 Wiley Periodicals, Inc.