β-Alanine-functionalized magnetic graphene oxide quantum dots: an efficient and recyclable heterogeneous basic catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 2,3-dihydroquinazolin-4(1H)-one derivatives

In this research, we report a novel synthesis of magnetic β-alanine-functionalized-graphene oxide quantum dots Fe₃O₄@GOQDs-N-(β-alanine) as a recyclable and eco-friendly heterogeneous nanocatalyst. The catalytic efficiency of these nanosheets was explored as a basic catalyst for a one-pot three-component synthesis of various 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 2,3-dihydroquinazolin-4(1H)-one derivatives. The reactions proceeded smoothly under mild and green conditions to afford the respected products in excellent yields. The structure of this newly fabricated catalyst was successfully confirmed by different analytical techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. The stability and recyclability of the catalyst were examined by performing the model reaction in six consecutive runs. The recovered catalyst from the first run was directly used for the next runs with no significant loss of catalytic activity.     

Meet the Cerium(IV) Phosphate Sisters: CeIV(OH)PO4 and CeIV2O(PO4)2

Two new cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO₄, and cerium(IV) oxidophosphate, Ce₂O(PO₄)₂, which were shown to complement the classes of isostructural compounds M(OH)PO₄ and R₂O(PO₄)₂, where M=Th, U and R=Th, U, Np, Zr. Ce₂O(PO₄)₂ oxidophosphate is formed by elimination of H₂O from the crystal structure of Ce(OH)PO₄ during its thermal decomposition. The structures of Ce(OH)PO₄ and Ce₂O(PO₄)₂ are related to each other with the same Cmce space group and similar unit cell parameters (a=6.9691(3) Å, b=9.0655(4) Å, c=12.2214(4) Å, V=772.13(8) ų, Z=8; a=7.0220(4) Å, b=8.9894(5) Å, c=12.544(1) Å, V=791.8(1) ų, Z=4, respectively).     

Potassium Natural Asphalt Sulfonate (K-NAS): Synthesis and characterization as a new recyclable solid basic nanocatalyst and its application in the formation of carbon–carbon bonds

In this research, we synthesized and characterized a new heterogeneous basic nanocatalyst and its catalytic application was studied in the Claisen-Schmidt and Knoevenagel condensations. In order to prepare this nanocatalyst, first, the Iranian natural asphalt was sulfonated with the concentrated sulfuric acid and then, converted to the potassium natural asphalt sulfonate (K-NAS). In order to characterization of the nanocatalyst, used of FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), inductively coupled plasma (ICP) and thermogravimetric analysis (TGA) techniques. This new basic heterogeneous nanocatalyst have advantages such as being eco-friendly, huge specific surface area, high reactivity and recyclability .     

Identification of Novel Influenza Polymerase PB2 Inhibitors Using a Cascade Docking Virtual Screening Approach

To discover novel inhibitors that target the influenza polymerase basic protein 2 (PB2) cap-binding domain (CBD), commercial ChemBridge compound libraries containing 384,796 compounds were screened using a cascade docking of LibDock–LigandFit–GOLD, and 60 compounds were selected for testing with cytopathic effect (CPE) inhibition assays and surface plasmon resonance (SPR) assay. Ten compounds were identified to rescue cells from H1N1 virus-mediated death at non-cytotoxic concentrations with EC₅₀ values ranging from 0.30 to 67.65 μM and could bind to the PB2 CBD of H1N1 with Kd values ranging from 0.21 to 6.77 μM. Among these, four compounds (11D4, 12C5, 21A5, and 21B1) showed inhibition of a broad spectrum of influenza virus strains, including oseltamivir-resistant ones, the PR/8-R292K mutant (H1N1, recombinant oseltamivir-resistant strain), the PR/8-I38T mutant (H1N1, recombinant baloxavir-resistant strain), and the influenza B/Lee/40 virus strain. These compounds have novel chemical scaffolds and relatively small molecular weights and are suitable for optimization as lead compounds. Based on sequence and structure comparisons of PB2 CBDs of various influenza virus subtypes, we propose that the Phe323/Gln325, Asn429/Ser431, and Arg355/Gly357 mutations, particularly the Arg355/Gly357 mutation, have a marked impact on the selectivities of PB2 CBD-targeted inhibitors of influenza A and influenza B.     

如何理解热力学基本方程dG=-SdT+Vdp的适用条件*

从热力学第一定律和热力学第二定律出发推导了热力学基本方程dG=-SdT+Vdp;然后围绕 dG=-SdT+Vdp的适用条件做细致分析,分别从简单pVT变化、相变化和化学变化等3个方面着手,逐一举例并详细解题、分析,探讨对该公式的应用条件,得出相应的结论。为学生在热力学基本方程应用过程中的问题提供新思路。     

Synthesis,crystal structure and thermal stability of new copper(II) trichloroacetate complexes

We have synthesized two novel complexes of copper(II) trichloro acetate, Cu₂(CCl₃COO)₃(OH)(H₂O)₄·H₂O and Cu(CCl₃COO)₂(MeCN), and determined their crystal structures and thermal stability. While the complex with acetonitrile has a discrete binuclear paddle-wheel structure, typical of copper carboxylates, the aqua-hydroxo complex belongs to a novel unique chain–molecular type of basic copper complexes.     

人口算子的谱性质

本文讨论人口算子的谱性质,得到了人口算子本征值除可能有限个外均是代数单的,人口算子本征值新的分布性质,人口算子广义本征函数不构成基序列,Ｌ２［０,ｒ２］上的人口算子根子空间完整等．     

聚乙烯吡咯烷酮动态涂敷毛细管电泳柱分离碱性蛋白质

以聚乙烯吡咯烷酮(PVP)为添加剂对毛细管柱进行动态修饰,用于碱性蛋白分离。对4种碱性蛋白质进行分离,实验结果表明聚乙烯吡咯烷酮能够很好地抑制电渗流(EOF)及碱性蛋白在石英毛细管壁上的吸附作用。在pH4.0,PVP浓度(W/V)为0.4％时,EOF仅为1.35×10~(-9) m~2/V.s,平均柱效可达5×10~5理论塔板数/m。每次运行之间(n=6),天与天之间(n=6),迁移时间的相对标准偏差(RSD％)分别小于1％和3％,表明该动态涂敷方法具有良好的重现性和稳定性。另外,由于PVP的粘度较小,使得该方法操作方便、快捷。     

含三乙烯二胺强弱碱功能基阴离子交换树脂的制备及其吸附性能

含三乙烯二胺强弱碱功能基阴离子交换树脂的制备及其吸附性能;三乙烯二胺; 强弱碱基阴离子交换树脂; 滴定曲线; 苯甲酸; 吸附性能     

Chiral Separation of Racemates of Drugs and Amino Acid Derivatives by High-Performance Liquid Chromatography on a Norvancomycin-Bonded Chiral Stationary Phase

A novel norvancomycin-bonded chiral stationary phase (NVC-CSP) has been synthesized by use of the chiral selector norvancomycin, which differs from vancomycin because of the presence of leucine rather N-methylleucine. The enantiomers of some neutral and basic chiral drugs, for example warfarin, benzoin, bendroflumethiazide, and praziquantel, were directly separated by high-performance liquid chromatography in the reversed-phase mode. The effect of conditions such as organic modifier concentration, column temperature, pH, and mobile phase flow rate on retention and enantioselectivity were investigated. It was shown that hydrophobic, steric, and ionic interactions were present between the analyte and the macrocycle in this chromatographic system. Vant Hoff plots afforded the thermodynamic data _R,SH° and _R,SS°; the negative values obtained indicated the process of enantiomer separation was enthalpy-controlled. In an attempt to improve the resolution of some very polar acidic compounds (dansyl-amino acids) norvancomycin was used as stationary phase chiral selector and chiral mobile-phase additive simultaneously, better results were obtained as the result of a synergistic effect. It was also shown experimentally that the newly synthesized NVC-CSP behaved somewhat differently from the earlier reported vancomycin-bonded CSP, probably because of the different structures of norvancomycin and vancomycin.