Pyrolysis mechanism of trisbipyridineiron(II) chloride to iron nanoparticles

Pyrolysis of trisbipyridineiron(II) chloride under controlled thermal conditions and inert atmosphere of argon gas yields a residue of iron nanoparticles. Evolved gas analysis by GC?CMS and ¹H NMR revealed emission of bipyridine, 6-chlorobipyridine, 6,6??-dichlorbipyridine, bipyridine hydrochloride, and hydrochloric acid as decomposition products. CHN, XRPD, EDXRF, TEM, AFM, and ⁵⁷Fe M?ssbauer spectroscopy of the residue indicated formation of pure iron nanoparticles in the size range of 50?C72?nm. Based on these results a mechanism for thermal degradation of trisbipyridineiron(II) chloride has been worked out.     

Synthesis,characterization, anti-fungi and anti-bacterial activity of new [(2-pyridyl)-3-isatin]-bishydrazone

New [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetylpyridine)-3-isatin]-bishydrazone (apish), and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bpish) have been synthesized and characterized by the elemental analysis, IR, NMR and electronic spectra. The bioefficiency of the [(2-pyridyl)-3-isatin]-bishydrazones have been examined for their in-vitro antibacterial and antifungal activity against many types of bacteria and fungal cultures which are common contaminants of the environment in Egypt and some of which are involved in human and animal diseases or in plant diseases or frequently reported from contaminated soil, water, and food substances. The results of these studies indicate that the [(2-pyridyl)-3-isatin]-bishydrazones possess notable antimicrobial properties.     

The Implication of Low Dose Dimethyl Sulfoxide on Mitochondrial Function and Oxidative Damage in Cultured Cardiac and Cancer Cells

Although numerous studies have demonstrated the biological and multifaceted nature of dimethyl sulfoxide (DMSO) across different in vitro models, the direct effect of “non-toxic” low DMSO doses on cardiac and cancer cells has not been clearly explored. In the present study, H9c2 cardiomyoblasts and MCF-7 breast cancer cells were treated with varying concentrations of DMSO (0.001–3.7%) for 6 days. Here, DMSO doses < 0.5% enhanced the cardiomyoblasts respiratory control ratio and cellular viability relative to the control cells. However, 3.7% DMSO exposure enhanced the rate of apoptosis, which was driven by mitochondrial dysfunction and oxidative stress in the cardiomyoblasts. Additionally, in the cancer cells, DMSO (≥0.009) led to a reduction in the cell’s maximal respiratory capacity and ATP-linked respiration and turnover. As a result, the reduced bioenergetics accelerated ROS production whilst increasing early and late apoptosis in these cells. Surprisingly, 0.001% DMSO exposure led to a significant increase in the cancer cells proliferative activity. The latter, therefore, suggests that the use of DMSO, as a solvent or therapeutic compound, should be applied with caution in the cancer cells. Paradoxically, in the cardiomyoblasts, the application of DMSO (≤0.5%) demonstrated no cytotoxic or overt therapeutic benefits.     

Chlorosulfonyl styrene–divinylbenzene copolymer characteristics as a function of chlorosulfonation and chlorination reaction parameters

Chlorosulfonyl substituted styrene–divinylbenzene copolymer is a highly reactive intermediate used in organic synthesis. It is obtained in three steps: (1) the polymeric support in the form of spherical beads is prepared by free radical polymerization of styrene; (2) the divinylbenzene mixture and the aromatic styrene groups of the obtained copolymer are sulfonated with chlorosulfonic acid in dichloroethane and (3) this is followed by chlorination of the sulfonyl groups with PCl₅/POCl₃ mixture. Chemical analysis shows that chlorosulfonation leads to both sulfonyl and chlorosulfonyl products in which content and ratio vary as a function of reaction parameters: maximum total group content of 5.1 meq/g is reached after 3 hr reaction, at 40°C with styrene to a chlorosulfonic acid molar ratio of 12.4:1. In the chlorination reaction, sulfonyl to chlorosulfonyl conversion is also observed to vary as a function of time and chlorinating mixture composition: 99.6 mol% conversion degree is attained after 2 hr reaction with styrene/PCl₅/POCl₃ in a molar ratio of 1:4:23. © 1997 John Wiley & Sons, Ltd.     

Cation-exchange resins and non-ionic cross-linked polymers in analysis of aqueous solutions for organic contaminants

Cyclohexane derivatives with a hydroxyl or carboxylic acid group separated by one or two methylene groups from the ring are, in acidified aqueous solution, adsorbed more strongly than the corresponding aromatic compounds both on sulfonated styrene—divinylbenzene resins and on non-ionic styrene—divinylbenzene resins. These observations and the lower temperature dependence observed for the cyclohexane derivatives indicate that hydrophobic interactions have a marked influence on the adsorption. Possible losses of non-ionic compounds by adsorption on cation-exchange resins and by leakage through columns packed with non-ionic resins used for concentration of organic compounds are discussed.     

Amine-catalyzed preparation of oxygenated derivatives of symmetric trisulfides

Bipyridinium tribromide reacts with thiols in the presence of thionyl chloride to yield symmetric trisulfide derivatives (RSS(O)SR) as the major products. Two possible mechanisms are advanced to explain the chemistry.     

A mixed hybrid formulation based on oscillated finite element polynomials for solving Helmholtz problems

A mixed-hybrid-type formulation is proposed for solving Helmholtz problems. This method is based on (a) a local approximation of the solution by oscillated finite element polynomials and (b) the use of Lagrange multipliers to “weakly” enforce the continuity across element boundaries. The computational complexity of the proposed discretization method is determined mainly by the total number of Lagrange multiplier degrees of freedom introduced at the interior edges of the finite element mesh, and the sparsity pattern of the corresponding system matrix. Preliminary numerical results are reported to illustrate the potential of the proposed solution methodology for solving efficiently Helmholtz problems in the mid- and high-frequency regimes.     

组合脉冲宽带激发2H-平均哈密顿理论计算研究

四级核回波实验通常需要射频脉冲能够激发谱宽超过100 kHz 的信号．在最近的研究中,作者发现组合脉冲COM-II (9018090135 45) 能够在氘核的四级核回波实验中实现宽带激发．此外,作者还结合了八步相位循环的方法,有效消除了由有限脉宽效应造成的谱图扭曲现象．利用了平均哈密顿原理,对该方法进行了理论计算研究．作者采用了自旋为1 的矩阵算符,通过计算解释了八步相位循环能够消除谱图扭曲的原因．     

Investigation of the optimal annealing temperature for the enhanced thermoelectric properties of MOCVD-grown ZnO films

In this study, we demonstrate the optimization of the annealing temperature for enhanced thermoelectric properties of ZnO. Thin films of ZnO are grown on a sapphire substrate using the metal organic chemical Vapor Deposition (MOCVD) technique. The grown films are annealed in an oxygen environment at 600–1000°C, with a step of 100°C for one hour. Seebeck measurements at room temperature revealed that the Seebeck coefficient of the sample that was not annealed was 152 μV/K, having a carrier concentration of N _D ~ 1.46 × 10¹⁸ cm^–3. The Seebeck coefficient of the annealed films increased from 212 to 415 μV/K up to 900°C and then decreased at 1000°C. The power factor is calculated and found to have an increasing trend with the annealing temperature. This observation is explained by the theory of Johnson and Lark–Horovitz that thermoelectric properties are enhanced by improving the structure of ZnO thin films. The Hall measurements and PL data strongly justify the proposed argument.     

Characterization of Sulfur-Compounds as Chemotaxonomic Markers in the Essential Oils of Allium Species by Solvent-Free Microwave Extraction and Gas Chromatography–Mass Spectrometry

Allium species were examined to authenticate the chemotaxonomic controversy about these plants by analyzing their extracted compound profiles. Essential oils of various species were isolated using conventional hydro-distillation and solvent-free microwave extraction (SFME). A comparison of the isolation procedures was performed. The presence of sulfur compounds in the Allium genus is a prominent characteristic for their medicinal uses. These components were characterized using two-way hierarchical cluster analysis (HCA) and principal component analysis (PCA). The variation of sulfur-compounds was performed by qualitative analysis of Allium species by gas chromatography–mass spectrometry (GC–MS). 2,4-Dimethyl-5,6-dithia-2,7-nonadienal, 4,6-diethyl-1,2,3,5-tetrathiolane, and 5,7-diethyl-1,2,3,4,6-pentathiepane were revealed as potential chemotaxonomic markers for all of the Alliums examined in this study. These markers may be used to provide improved systematics for other Allium species.