Materials Literature
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Enantioselective enzymatic acylation, using Lipase PS® (Pseudomonas sp., immobilized on Celite, Amano Pharmaceutical Co., Ltd.), of endo-dihalosubstituted and nonsubstituted dispiro[2.0.2.1]heptylmethanol and endo-4-methylenespiropentylmethanol provided the corresponding optically active compounds in high enantiomeric…
Dispersion polymerization of styrene (S) and vinylbenzyltrimethylammonium chloride (VBA) was conducted in an ethanol-water medium using an aromatic poly(amic acid) (PAA) as the stabilizer. When equimolar amounts of VBA and the carboxylic acid of PAA were used, monodisperse particles with high PAA content were obtained…
Dysprosium disilicate (Dy(2)Si(2)O(7)) is triclinic with a = 6.6158 (2), b = 6.6604 (2), c = 12.0551 (4) A, alpha = 94.373 (2), beta = 90.836 (2), gamma = 91.512 (2) degrees, V = 529.4 (1) A(3), space group P1;, Z = 4 and D(x) = 6.156 g cm(-3). The structure (single-crystal X-ray, R = 0.033, wR = 0.041) is built from…
Abstract X-ray diffraction analysis elucidated that a pair of hexaarylbiimidazoles was transformed to a complex composed of two lophyl radicals and a piezodimer on irradiation at low temperatures. The piezodimer, the existence of which has been assumed spectroscopically as an unstable isomer, was produced via molecula…
Drastisch weniger mehrfach oxygenierte Arene entstehen als Nebenprodukte bei der eisenkatalysierten Oxidation von Benzol zu Phenol mit H2O2 in einem MeCN/H2O-Zweiphasensystem. Mit 5-Carboxy-2-methylpyrazin-N-oxid als Eisenligand konnte dabei Benzol zu 8.6 % umgesetzt werden, wobei die Selektivität der Reaktion bezogen…
The Raman spectra of some common naturally occurring pseudo-alums, wupatkiite [CoSO4·Al2(SO4)3·22H2O], apjohnite [MnSO4·Al2(SO4)3·22H2O] and halotrichite [FeSO4·Al2(SO4)3·22H2O] were obtained at 298 and 77 K. Bands were observed at 996 and 990 cm−1 and assigned to the ν1(Ag) SO4 vibration. A band was observed at 972 c…
Heat Treatment of Gears: A Practical Guide for Engineers describes the processes and procedures used to harden alloy steel gears and explains how to optimize benefits, such as improved fatigue life, while minimizing distortion and costs. The first few chapters familiarize readers with the basic concepts of heat treati…
The genetic operon for propionic acid degradation in Salmonella enterica serovar Typhimurium contains an open reading frame designated prpE which encodes a propionyl coenzyme A (propionyl-CoA) synthetase (A. R. Horswill and J. C. Escalante-Semerena, Microbiology 145:1381-1388, 1999). In this paper we report the clonin…
The crystal structure of the two isostructural rare earth tungstates Ln 6 WO 12 ( Ln = Y , Ho ) has been refined by the Rietveld method from X-ray powder diffraction data. They crystallize with a three-dimensional rhombohedral structure (S.G. R 3¯ and Z =3 for the R -centered setting) closely related to that of the bi…
During hollow fiber spinning many variables are involved whose effects are still not completely clear. However, its understanding is of great interest because the control of these variables may originate membranes with the desired morphologies and physical properties. In this work, the phase inversion process induced…
Tradicionalmente, as embalagens para alimentos têm sido planejadas para proteger o produto; um de seus principais requisitos é a não interação com o alimento acondicionado, funcionando assim como uma barreira inerte entre o alimento e o ambiente. Entretanto, as tecnologias envolvendo embalagens ativas visam o planejam…
We report here new Ar-Ar dates for adularia, illite, and muscovite from the Twin Creeks Carlin-type deposit. All illite samples were obtained from altered intrusive and volcanic rocks that are interlayered with mineralized sedimentary rocks, thus largely avoiding complications caused by detrital illite and muscovite i…
This paper summarizes the results obtained in the MICAT project for mild steel specimens exposed for 1 to 4 years in 47 marine atmospheres in the Ibero-American region. All these atmospheres were characterized for climatology, pollution and corrosion rates according to ISO standards. Complementary morphological and ch…
Electrochemically formed porous silicon (PS) can be released from the bulk silicon substrate by underetching at increased current density. Using this technique, two types of channels containing free-standing layers of PS were constructed, which were failed multi-walled microchannels (MW /spl mu/Cs). They can be used i…
KMgF 3 (KMF) single crystals were grown by the Czochralski technique as a new candidate of vacuum-ultra-violet optical materials. The absorption edge of KMF single crystals was 115 nm. The distribution of birefringence in the radial direction was of the order of 10 -7 . The thermal expansion coefficient of KMF single…
Abstract There are two different views regarding the genesis of gibbsite in tropical acid soils: (1) direct weathering of primary Al-silicate minerals; and (2) transformation through clay mineral intermediates. We investigated the genesis of gibbsite in two representative Ultisols from northeastern India. Gibbsite in…
The removal of small particles is vital for contamination-free manufacturing. In humid environments liquid can condense between the particle and substrate and give rise to a very large capillary force, which increases the total force of adhesion. The removal and adhesion forces of polystyrene latex (PSL) particles and…
Tetragonal ZrO 2 nanocrystallites—with or without yttria (3 mol%) doping—have been synthesized via a precipitation process in which the hydrous oxide precipitate reacts with hexamethyldisilazane (HMDS) vapor before calcination. The nanocrystallites are formed and retain a tetragonal structure for hours after calcinati…
Blazed-binary gratings for which a blazed effect with binary etches is achieved under normal incidence offer first-order diffraction efficiencies larger than those of blazed-échelette gratings in the resonance domain [Opt. Lett. 23 1081 (1998)]. We provide further insight into the behavior of blazed-binary gratings an…
Aluminum subjected to smooth mechanical loading does not often deform in a correspondingly smooth manner. Typically it deforms inhomogeneously through the propagation of deformation fronts that slowly traverse the sample. These are called Portevin-Le Chatelier fronts; what determines their velocity has been somewhat m…