The first compound with an unusual type of anion, [Li(SR)2]–: bis­(μ2‐aqua‐d2)tetra­kis(aqua‐d2)dilithium(I) bis­[bis­(tri‐tert‐butoxy­silanethiol­ato‐κ2O,S)lithate(I)] dihydrate‐d2

The title complex, [Li₂(D₂O)₆][Li(C₉H₂₇SSiO₃)₂]₂·2D₂O, is the first compound with an S—M bond (M = alkali metal) within an unusual type of lithate anion, [Li(SR)₂]⁻ {where R is Si[OC(CH₃)₃]₃}. There is a centre of symmetry located in the middle of the Li₂O₂ ring of the cation. All Li atoms are four‐coordinate, with LiO₄ (cations) and LiO₂S₂ (anions) cores. The singly charged [Li(SR)₂]⁻ anions are well separated from the doubly charged [Li₂(D₂O)₆]²⁺ cations; the distance between Li atoms from differently charged ions is greater than 5 Å. Both ion types are held within an extended network of O—D⋯O and O—D⋯S hydrogen bonds.     

Fragmentation reactions of some aliphatic esters in the NCl(F−) and NCl(NH2−) mass spectra

The NCI(F^?) and NCI(NH₂^?) mass spectra of a series of aliphatic acetates and of methyl and ethyl trimethylacetate have been obtained. The formation of fluoroenolate ions CH₂COF^? and of carboxamide anions RCONH^? (R ? CH₃))CH₃C). respectively, is observed besides formation of [M ? H]^? ions and carboxylate ions RCOO^? (R ? CH₃, (CH₃)₃C). The relative intensities of the different anions depend on the structure of the ester molecules and on the primary reactant anions. Usually, the NCI(NH₂^?) spectra of the acetates are dominated by [M ? H]^? ions ([M? D]^? ions in the case of trideuteroacetates) fragmenting unimolecularly by elimination of an alcohol. The carboxylate ions are important fragments, too, but carboxamide ions are only observed with large intensities in the NCI(NH₂^? spectra of the trimethylacetates. The NCI(F^?) spectra show much larger intensities of carboxylate ions and fluoroenolate ions. The mechanisms of the fragmentation reactions are discussed. The results indicate that most or even all of the fragment ions in the NCI(F^? mass spectra of aliphatic esters are formed by addition-elimination reactions via a tetrahedral intermediate, while competition between direct proton abstraction and addition-elimination reactions occurs in the NCI(NH₂^?) mass spectra because of the higher basicity of NH₂^? resulting in an early transition state for direct proton abstraction.     

Kinetics of particle deposition in the oblique impinging jet cell

A new oblique impinging-jet (OBIJ) cell was developed, suitable for colloid deposition studies at various interfaces. In contrast to previously used orthogonal cells, the OBIJ construction makes possible direct microscope observations of particle deposition on nontransparent substrates. The cell performance was tested by studying kinetics of polystyrene latex particle deposition on mica. Two limiting cell configuration were used in the experiments: (i) the lower position (inverted microscope observation of substrate surface through air) and (ii) the upper position (observation of the substrate surface with adsorbed particles through the suspension layer). The dependence of local mass transfer rate (particle flux) on the position over the substrate surface was studied for various flow Reynolds numbers. It was demonstrated that deposition rate attained maximum at the flow stagnation point whose position was dependent on Re number. Moreover, it was shown that the local flux decreased at much slower rate when moving in the downstream direction, than for previously used impinging-jet cells. Consequently, the area of uniform transport conditions was larger, enabling more precise determination of the limiting particle flux at the stagnation-point. The dependence of the flux on Re number was systematically studied for various ionic strength of the suspension. It was demonstrated, in accordance with previous results for the ordinary impinging-jet, that the flux increased significantly for low ionic strength and high Re number. This phenomenon, referred to as the inverse salt effect, was interpreted in terms of the convective diffusion theory. The governing transport equation originating from this theory was solved numerically, for the region near the stagnation point, using the finite-difference method. These numerical solutions were used for nonlinear fitting of the flow intensity parameter dependence on the Re number. In this way the flow field in the vicinity of the stagnation point was fully characterized. It was concluded that the new cell can be exploited as an effective experimental tool for colloid deposition studies on various substrates.     

Solubility of Solid 2-Methyl-1,3-butadiene (Isoprene) in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubility of solid 2-methyl-1,3-butadiene (isoprene) in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K has been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in the solute. The experimental value of the mole fraction solubility of solid isoprene in liquid argon at 87.3 K is (1.41 ± 0.27) × 10^–6 and (1.56 ± 0.36) × 10^–7 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for isoprene than is liquid nitrogen. The experimental values of the solubilities of isoprene in liquid argon and nitrogen were compared with results obtained for selected unsaturated and aromatic hydrocarbons.     

über einige Kondensationsreaktionen von dimerem Malonitril, dimerem Cyanessigs?ure?thyl- bzw.-methylester mit aromatischen Aldehyden

Aromatic aldehydes (1 a-g) yield linear condensation products (3 a-1) with dimeric ethyl and methyl cyanoacetate, resp., and dimeric malonitrile. Reduction of the condensation product of o-nitrobenzaldehyde with dimeric methyl cyanoacetate leads to methyl (3-methoxycarbonyl-1,2-dihydro-2-chinolinylidene)-cyanoacetate (4), with o-aminobenzaldehyde a carbostyril derivative5 a is obtained. In the presence of ammonium acetate aromatic aldehydes react with dimeric methyl and ethyl cyanoacetate, resp. to hexahydro-pyrimidinylidene cyanoacetates (8).     

THE EFFECTS OF NEAR-UV RADIATION ON HUMAN LENS β-CRYSTALLINS: PROTEIN STRUCTURAL CHANGES and THE PRODUCTION OF O2_ and H2O2

beta-Crystallins (beta 1-, beta 2- and beta 3-crystallin) comprise nearly half the protein of the human lens. The effect of near-UV radiation, which is one of the possible risk factors in cataract formation, on the beta-crystallins is investigated in this study. Protein intersubunit crosslinking, change in charge of the protein subunits to more acidic species and changes in protein tertiary structure (conformation) by 300 nm irradiation are reported. The fluorescence yield of protein tryptophan residues decreases by 300 nm irradiation. There is an increase in nontryptophan fluorescence (lambda cx 340 nm, lambda cm 400-600 nm), and in protein absorption at 340 nm, due to the formation of tryptophan photooxidation products. Both tryptophan and its oxidation products can be photoexcited by 300 nm irradiation and the latter are known to be good photosensitizers. The results provide evidence for the generation of H2O2 in the irradiated human beta-crystallin solutions by the Type I photosensitizing action of the chromophores absorbing at 300 nm. The H2O2 is generated via the intermediate production of O2 anion; the latter spontaneously dismutates to H2O2, presumably via O2- protein interactions. The amount of H2O2 generated per absorbed photon is compared for various solutions of beta 1-, beta 2- and beta 3-crystallins from human lenses of different age.     

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.     

InIII-Phthalocyanine: Darstellung,Eigenschaften und Kristallstruktur von Tetra(n-butyl)ammonium-cis-di(nitrito-O,O′)phthalocyaninato(2–)indat(III)

In^III-Phthalocyanines: Synthesis, Properties, and Crystal Structure of Tetra(n-butyl)ammonium-cis-di(nitrito-O,O')phthalocyaninato(2–)indate(III) [In(Cl)Pc^2?] reacts with (ⁿBu₄N)NO₂ in acetone yielding green-blue (ⁿBu₄N)^cis[In(NO₂)₂Pc^2?], which crystallizes in the monoclinic space group P2₁/n (No. 14). Both nitrite anions are coordinated as chelating nitrito-O,O'(NO₂) ligands to In^III in cis-geometry. Consequently In^III is octa-coordinated within a distorted “quadratic” antiprism and directed towards the Pc^2?-ligand. One of the NO₂ ligands has equivalent N? O bonds similar to free nitrite, while the other has asymmetric N? O bonds. Both (In,O,N,O) rings are approximately planar with a dihedral angle of 80°. The Pc^2? ligand is distorted in an asymmetrically convex manner. Partially overlapping pairs of Pc^2? ligands related by an inversion center form double layers, which are separated by layers containing the (ⁿBu₄N)⁺ cations. The cyclic voltammogram shows three electrode processes, which are assigned to the redox pairs: Pc^3?/Pc^2? (?0.94 V) < In^I/In^III (-0.78 V) < Pc^2?/Pc^? (0.64 V). The UV-VIS-NIR spectra and vibrational spectra are discussed.     

More on limit theorems for iterates of probability measures on semigroups and groups

Summary In this paper, we continue earlier works of one of the authors on vague convergence of the sequence _k,n= _k+1 *...* _n, where _n is a sequence of probability measures on semigroups or groups. Typical results in this paper are: Theorem. Let S be a locally compact noncompact second countable group such that being the support of a probability measure on S. Suppose there exists an open set V with compact closure such that x ^–1 Vx=V for every xS. Then for all compact sets K, sup{ ⁿ (Kx): xS0 as n. Theorem. Let S be an at most countable discrete group. Let _n be a sequence of probability measures on S. Then for all nonnegative integers k, the sequence _k,n converges vaguely to some probability measure if and only if there exists a finite subgroup G such that the series and for any proper subgroup G of G and any choice of elements g_n in S, the series . A sufficient condition for the vague convergence of the sequence _k,n to a probability measure is that (i) there exists a finite subgroup G such that and (ii) _n(e)>s>0 for all n, e being the identity.The author was supported by NSF grant MCS77-03639