Environmental Effect of Macrocyclic Molecules on the Oxidation of Triethylamine by Ferricyanide Ion in Aqueous Solution

The effect of 18-crown-6 and kryptofix (2,2,1) on the oxidation of triethylamine byaqueous ferricyanide ion has been studied at pH 4, 7, and 9.The macrocycle retarded the normal oxidation process at all pH values,the effect depending on the macrocyclic ligand concentration Kryptofix (2,2,1) had a greater effect than 18-crown-6 at all pHvalues in this study. For 18-crown-6, retardation decreases in the order pH 9 > 4 > 7 while forkryptofix it follows the order pH 9 > 7 > 4.     

Unique charge-separated intermolecular and eight-membered intramolecular H-bonds in bis-(thio)barbiturates

Reaction of symmetrical and unsymmetrical (thio)barbituric acids with aldehydes in the presence of triethylamine afforded a new form of bis-(thio)barbiturate containing charge-separated inter- and eight-membered intramolecular H-bonds. The reaction products were obtained as bis-(thio)barbiturates containing eight-membered intramolecular H-bond in the presence of l-(+)-tartaric acid (TA). The intramolecular H-bond strength (kcal/mol) and corresponding pKa value for 4ab′ were estimated to be 37 kcal/mol and ?1.3, respectively.     

采自新疆北部Lecanora属的新记录地衣种

茶渍属地衣广泛分布于新疆北部.其基本特征为几乎都具有特久的子囊盘,子囊盘茶渍型.绝大多数茶渍属地衣适应于生活在干旱半干旱地区.它们对环境的适应性能力强.我们在进行分类的过程中,采用微量化学结晶法(MCT),薄层色谱法(TLC)等方法检测地衣物质,通过观察子囊盘结构、颜色和对地衣次生产物的分析,并对采自于新疆阿勒泰山哈纳斯自然保护区和天山天池所采集的茶渍属(Lecanora Ach.in Luyken) 300余号标本进行了整理及分类,初步定名新疆新记录地衣3种(Lecanora cenisia Ach , Lecanora crenulata,Lecanora intricata) ,本文对此三种新疆新记录地衣进行详细的描述并提供了三种新疆新记录地衣的彩色图片.所引用标本均保存于新疆大学资源植物标本室.     

Design and preparation of imprinted surface plasmon resonance (SPR) nanosensor for detection of Zn(II) ions

A novel Zn(II) ions imprinted poly (2-hydroxyethyl Methacrylate-N-methacryloyl-(L)-histidine methyl ester) poly(HEMAH) surface plasmon resonance (SPR) nanosensor were designed for detection of Zn(II) ions in aqueous solution and artificial plasma providing a low cost, rapid and reliable results compared to other techniques such as atomic absorption spectroscopy, inductively coupled plasma-mass spectrometer, X-ray fluorescence with synchrotron radiation. Zn(II) ions imprinted nanofilm on the SPR chip surface was synthesized by bulk polymerization. Characterization of Zn(II) ions imprinted nanosensor was performed by contact angle measurement, atomic force microscopy (AFM), ellipsometry and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR). Designed nanosensor was applied for selective detection of Zn(II) ions in aqueous solution within the range of 0.5–1.0?µg/mL. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.19 and 0.64?ng/mL, respectively. Association kinetics analysis, Scatchard, Langmuir, Freundlich, Langmuir–Freundlich, Tempkin and Dubinin-Radushkevich isotherms were analyzed to the experimental data in order to identify the adsorption behavior. The selectivity of the SPR nanosensor was examined by using competitive metal ions such as Cd(II), Cu(II), Pb(II), and Fe(II). To evaluate the imprinting effect of Zn(II) ions imprinted (MIP) and non-imprinted (NIP) nanosensor was also prepared as the control. Repeatability of the response signal was tested by four times adsorption–desorption–regeneration cycle.     

New one-pot synthesis of spiro[furo[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine-6,5′-pyrimidine]pentaones and their sulfur analogues

Reaction of barbituric acid (BA), 1,3-dimethyl barbituric acid (DMBA) and 2-thiobarbituric acid (TBA) with cyanogen bromide and various aldehydes in presence of triethylamine afforded a new class of heterocyclic stable 5-alkyl and/or 5-aryl-1H, 1′H-spiro[furo[2,3-d]pyrimidine-6,5′-pyrimidine]2,2′,4,4′,6′(3H,3′H,5H)-pentaones which are dimeric forms of barbiturate (uracil and thiouracil derivatives) at 0 °C to ambient temperatures. Structure elucidation is proved by X-ray crystallography, ¹H NMR, ¹³C NMR, FT-IR, CHN and mass analyses techniques. Mechanisms of the formations are discussed.     

A revised Cattaneo-Christov micropolar viscoelastic nanofluid model with combined porosity and magnetic effects

The dynamics of non-Newtonian fluids along with nanoparticles is quite interesting with numerous industrial applications. The current predominately predictive modeling deals with the flow of the viscoelastic micropolar fluid in the presence of nanoparticles. A progressive amendment in the heat and concentration equations is made by exploiting the Cattaneo-Christov(C-C) heat and mass flux expressions. Besides, the thermal radiation effects are contributed in the energy equation and aspect of the ...     

Synthesis,Characterization and Crystal Structure of Some Novel 1‐(3,5‐Dimethyl‐1H‐pyrazol‐1‐yl)‐3‐(substituted anilino)propan‐1‐ones

Michael addition of some substituted anilines to methyl acrylate in acidic medium afforded the methyl 3-(substituted anilino)propionates (1a—1i), which on treatment with hydrazine hydrate in methanol were converted into corresponding 3-(substituted anilino) propionohydrazides (2a—2i) in good yields. Microwave irradiation of the latter with pentane-2,4-dione afforded 1-(3,5-dimethyl-1H-pyrazol-1-yl)-3-(substituted anilino)propan-1-ones (3a—3i) under solventless conditions. The structures were confirmed by spectroscopic data, elemental analyses and in case of the 3h by single crystal X-ray diffraction data.     

NON-EQUILIBRIUM MICROWAVE RESPONSE OF Yba2Cu3O7-δ GRANULAR THIN FILMS UNDER MAGNETIC FIELDS

Microwave responses of YBa₂Cu₃O_7-δ(YBCO) granular film have been studied at the microwave frequency of 30.5 GHz. In the absence of a magnetic field the dependence of a normal microwave response on the bias current is observed at a temperature close to T_c. When a magnetic field ranged from 5.0 mT to 33.0 mT is applied, the responses broaden and shift toward a lower temperature. In the superconducting state, the responses were found to be highly dependent on the magnetic field. For the current equal to 5.0mA and a magnetic field above 17.0mT the response increases and did not vanish even at a very low temperature, the fact is believed to be correlated to the anisotropic character of the structure.