Molecular Structure of Bis(trimethylsilyl) Hypophosphite HP(OSiMe3)2 by Gas-Phase Electron Diffraction and Quantum Chemistry

Geometric parameters and conformation of the bis(trimethylsilyl)hypophosphite molecule were determined by gas-phase electron diffraction and quantum-chemical calculations. The molecule has an asymmetric structure, including an asymmetric P(OSiMe₃)₂ group. The principal geometric parameters are as follows: (r _a; in parentheses are standard deviations): bond lengths: P-O 1.616 and 1.633(1), Si-O 1.670(1), Si-C 1.892(1), C-H 1.097(3) Å; bond angles: OPO 100.8(8), POSi 133.3, and 138.4(3)°; torsion angles about P-O bonds 120(2) and 41.(3)°; and torsion angles about Si-O bonds are 145 and −178(4)°.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 897–902.Original Russian Text Copyright © 2005 by Naumov, Oberhammer, Tafipol’skii.     

Synthesis and structure of optically active compounds [Ni(HL1)]NO3 and [Ni(HL2)]NO3H2O containing anions of diaminodioximes H2L1 and H2L2 derived from α-Pinene and (+)-3-Carene as Ligands

New optically active levorotatory compounds [Ni(HL¹)]NO₃ (I) and [Ni(HL²)]NO₃H₂O (II) containing the anions of chiral diaminodioximes, H₂L¹ and H₂L², derived from the terpenes ±-pinene and (+)-3-carene, respectively, were synthesized. Complexes I and II were studied by X-ray diffraction. The crystal structures of compounds are ionic, being composed of the [Ni(HL¹)]⁺ or [Ni(HL²)]⁺ cations and the outer-sphere NO₃^– anions. The Ni²⁺ ion coordinates four N atoms of the tetradentate chelating ligand, the NiN₄ coordination unit being shaped like a tetrahedrally distorted square. Compounds I and II are diamagnetic, which corresponds to a low-spin d⁸ configuration. The NMR spectra of compounds were recorded and analyzed.Translated from Koordinatsionnaya Khimiya, Vol. 30, No. 12, 2004, pp. 888–896.Original Russian Text Copyright © 2004 by Larionov, Myachina, Saveleva, Glinskaya, Klevtsova, Sheludyakova, Tkachev, Bizyaev.     

Determination of trace and platinum-group elements in high ionic-strength volcanic fluids by sector-field inductively coupled plasma mass spectrometry (ICP-MS)

The accurate measurement of ultra-trace concentrations of rare metals and platinum group elements in volcanic fluids is complicated by interferences, complex matrices, and preferential element partitioning. We analyzed condensed, high-temperature magmatic fluids collected from Kudryavy volcano (Kurile Islands, Russia) for Be, B, Rb, Sr, Mo, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi, and U using ICP-MS. The samples had three different matrices: 5 mol L^–1 sodium hydroxide (NaOH, pH = 11), gas condensates of sulfuric acid (H₂SO₄, pH = 0), and solid elemental sulfur. Interferences and suppression/enhancement effects were investigated using standards in concentrated NaOH and H₂SO₄ solutions to determine adequate dilution for sample analyses, which then required very low levels of element detection (< 1 μg L^–1 for most elements). Depending on the field sampling technique of volcanic gas vents, our results show significant differences in concentrations of some trace elements due to the precipitation of solid sulfur during gas condensation and variations in element volatility as a function of temperature.     

Photometric determination of carboxylic acid impurities in polymers and organic liquids with the use of the ion pair of trinonyloctadecylammonium and Bromothymol Blue as the colored reagent

A method was proposed for the photometric determination of carboxylic acid impurities in polyvinylchloride, food and machine oils, and other samples. The method is based on the interaction of the acid groups of the sample with the ion pair of Bromothymol Blue and the trinonyloctadecylammonium cation in the binary solvent toluene-tetrahydrofuran. The method is highly sensitive and reproducible and was tested with many samples.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 22–26.Original Russian Text Copyright © 2005 by Rakhmanko, Zhilko, Egorov.     

Synthesis and properties of 4,4′-bis[5-alkyl(aryl)benzoxazol-2-yl]-2-hydroxy(alkoxy)biphenyls

Synthesis of 2-hydroxy(methoxy)-4,4′-biphenyldicarboxylic acids was developed. Based on their reactions with o-aminophenols we prepared for the first time 4,4′-bis[5-alkyl(aryl)benzoxazol-2-yl]-2-hydroxy-(alkoxy)biphenyls, which might be of interest as luminescent dyes. Hydroxy compounds in a salt form possess abnormally high Stokes shift.     

Synthesis,structure, and properties of isomeric polyaminoacetophenones

In terms of the ability for electrochemical transformations in acidic medium, the reactivity decreases in the order o-aminoacetophenone > p-aminoacetophenone > m-aminoacetophenone > aniline. The products of electrochemical polycondensation of the ortho and para isomers are conductors. Oxidative polycondensation of o-aminoacetophenone forms emeraldin hydrosulfate, and with p- and m-aminoacetophenones, emeraldin and leucoemeraldin are formed. In terms of thermal stability, polyacetoaminophenones can be ranked in the order poly-o-aminoacetophenone > poly-m-aminoacetophenone > poly-p-aminoacetophenone.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 2012–2018.Original Russian Text Copyright © 2004 by Stratan, Kovalchuk, Blazejowski.This revised version was published online in April 2005 with a corrected cover date.     

Structural and mechanical study of elastomers under plane deformation

The plane shrinkage of various elastomers [natural rubber, synthetic isoprene rubber, and plasticized poly(vinyl chloride)] at room temperature has been studied via direct microscopic observations. Prior to deformation, the surface of polymer samples is decorated with a thin (several nanometers) metallic layer. Further deformation leads to formation of the surface relief in the coating. An analysis of the formed microreliefs allows one to visualize and characterize the induced stress field in the sample. The shrinkage of poly(vinyl chloride) samples is accompanied by development of the uniform surface relief over the whole surface of the deformed polymer. This fact suggests a homogeneous character of the stress field and, hence, a homogeneous structure of the polymer sample. In the case of crosslinked rubbers (natural rubber and synthetic isoprene rubber), their plane shrinkage leads to the development of an irregular pattern on the polymer surface. In addition to the folded surface relief that is typical of the poly(vinyl chloride) structure, one can observe 20-to 50-μm “islands,” which are characterized by their own morphological features. Information on structural inhomogeneity of rubbers that is obtained by scanning electron microscopy correlates with the data of DSC measurements. The advantages of electron microscopic procedure for studying structural rearrangements in polymers during strain recovery of elastomers are demonstrated.     

Effect of surface attachment on synthesis of bacterial cellulose

Gluconacetobacter spp. synthesize a pure form of hydrophilic cellulose that has several industrial specialty applications. Literature reports have concentrated on intensive investigation of static and agitated culture in liquid media containing high nutrient concentrations optimized for maximal cellulose production rates. The behavior of these bacteria on semisolid and solid surfaces has not been specifically addressed. The species Gluconacetobacter hansenii was examined for cellulose synthesis and colony morphology on a range of solid supports, including cotton linters, and on media thickened with agar, methyl cellulose, or gellan. The concentration and chemical structure of the thickening agent were found to be directly related to the formation of contiguous cellulose pellicules. Viability of the bacteria following freezer storage was improved when the bacteria were frozen in their cellulose pellicules. This article was authored by a contractor of the US government under contract no. DEAC05-00OR22725. Accordingly, the US government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US government purposes.     

马克思和阿伦特论“犹太人问题”

犹太人问题从来就不是一个固定的、指向明确的问题,但“犹太人问题”在历史上却始终是一个问题。如何解决“犹太人问题”？马克思从19世纪民族−国家的历史现实出发,对鲍威尔宗教的与世俗化的解决方式进行了反思和批判,进而得出解决犹太人问题必须在全人类解放的大背景下才能实现。通过将宗教问题还原为政治问题,将政治问题还原为市民社会对金钱的追求,马克思认为只有在实现了人的全面发展,也就是摆脱了资本的羁绊后,犹太人才可能获得真正的解放,这是一种“社会主义的解决方式”。而阿伦特则从对极权主义统治的反思,及构建一种“犹太家园”的可能方式出发,得出了一种基于“委员会制度”的“共和主义的解决方式”。在阿伦特看来,这种制度不仅是犹太人问题的解决方式,同时也是一种替代民族−国家和纳粹极权主义的政治形式的可能性,体现出一种新型政治哲学的内在希望。     

Leading order asymptotics in the Goldbeter–Koshland switch

An asymptotic analysis at leading order of the Goldbeter–Koshland switch, the simplest futile cycle, is carried out in detail. After a nondimensionalization of the problem, we find the leading order uniform expansions of the reactants, identifying the proper time scales in a total setting. Comparison with numerical integration confirms the goodness of our analysis.