Materials Literature
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The determination of alpha-amylase activity using an ethylidene-blocked 4-nitrophenyl-maltoheptaoside (EPS) has been evaluated in five laboratories on eight different analysers at 25 degrees C, 30 degrees C and 37 degrees C. The protecting ethylidene group inhibits hydrolysis at the non-reducing end of the substrate m…
Measurements were made of preferential uptakes of acetic acid from aqueous solution onto basic polymer sorbents.Individual uptakes of water and acetic acid were measured as well.The sorption equilibria were interpreted through a chemical complexation model yielding sorption affinities and capacities for acetic acid.Ba…
A mathematical model that describes the combined diffusion and reaction of trichloromethylsilane in a porous preform under typical chemical vapor infiltration (CVI) conditions is presented. The model utilizes a single pore to demonstrate the importance of the pore geometry, total gaseous pressure, temperature, and imp…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxidation of alkynes catalyzed by molybdenum(VI) and tungsten(VI) polyoxometalatesFrancesco Paolo Ballistreri, Salvatore Failla, Emanuela Spina, and Gaetano Andrea TomaselliCite this: J. Org. Chem. 1989, 54, 4, 947–949Publication Date (Print):February 1, 1989Publication Hist…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExperimental and theoretical study of tetrakis(di-p-tolylformamidinato)dimolybdenum and [Mo2(form)4]+ (form- = [(p-tol)NCHN(p-tol)]-)F. Albert Cotton, Xuejun Feng, and Marek MatuszCite this: Inorg. Chem. 1989, 28, 3, 594–601Publication Date (Print):February 1, 1989Publicatio…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUltraviolet photoelectron and ESR studies of 1,2,4,6-thiatriazinyl and 1,2,3,5-dithiadiazolyl radicalsRene T. Boere, Richard T. Oakley, Robert W. Reed, and Nicholas P. C. WestwoodCite this: J. Am. Chem. Soc. 1989, 111, 4, 1180–1185Publication Date (Print):February 1, 1989Pub…
Microcrystalline α‐aluminas (hexagonal plates, ∼0.1 μm wide and ∼0.025 μm thick) were prepared by treating fineparticle gibbsite in glycol at 300°C under the spontaneous vapor pressure of glycol (glycothermal treatment). The α‐alumina was formed by the collapse of the glycol derivative of boehmite.
By considering the Frank free energy, we show that the electric-field-induced twist and bend Freedericksz transitions can be first order. This agrees with the prediction of Arakelyan, Karayan, and Chilingaryan [Sov. Phys.--Dokl. 29, 202 (1984)] from Landau theory for the bend geometry. We have carried out dielectric m…
Nickel and lead phthalocyanine (NiPc and PbPc) thin films prepared by vacuum sublimation have been investigated for use as gas sensors. High sensitivity (25 ppb), reversibility, and very fast response time (∼ seconds) have been demonstrated for detection of NO2 at room temperature. The sensor output increases by five…
The pyrolysis of cross‐linked polycarbosilanes, polysilanes and polysilazanes in an ammonia atmosphere to 1473 K yields amorphous, low‐carbon silicon nitride powders. The efficacy of carbon removal is independent of the polymer's structure or functionality but is partially dependent on the initial cross‐linking temper…
Abstract New perfluorinated hemin carrys out hydroxylation of benzene by hydrogen peroxide at room temperature and an atmospheric pressure. The turnover for phenol produced for 2 hours is 55. This hemin also catalyses the epoxidation of cyclooctene by hydrogen peroxide.
We perform a nonrelativistic calculation of the first retardation and multipole corrections to the dipole angular distribution of 1s photoelectrons from light elements. A simple formula for this correction is obtained which compares well with the results of exact relativistic numerical calculations, for Z\ensuremath{\…
The Lactobacillus bulgaricus beta-galactosidase gene was cloned on a ca. 7-kilobase-pair HindIII fragment in the vector pKK223-3 and expressed in Escherichia coli by using its own promoter. The nucleotide sequence of the gene and approximately 400 bases of 3'- and 5'-flanking sequences was determined. The amino acid s…
A microscopic expression for the frequency and wave vector dependent dielectric constant of a dense dipolar liquid is derived starting from the linear response theory. The new expression properly takes into account the effects of the translational modes in the polarization relaxation. The longitudinal and the transver…
Cyclically induced crack propagation occurs in alumina subjected to direct tension—compression loading. The crack increment per cycle (da/dN) has a power‐law dependence on the peak stress intensity factor (K max ). Cyclic crack growth can occur at lower values of K max than are required to produce static fatigue effec…
Abstract A series expansion distribution function of the structure amplitude | F | has been used to calculate the generalised cumulative distribution function N n ( z ) for hypersymmetric crystals when there are n -fold repetitions of motifs at regular intervals ‘ d ’ along a straight line (both centrosymmetric and no…
The KMF 3 structures with M = Mn, Fe, Co and Ni have been investigated in detail using data from previous studies. The vibration amplitudes, atomic charges determined by difference density partitioning and the heights of characteristic features of the difference densities change monotonically through the series. Trend…
Abstract A kinetic model was developed to describe the rate of reaction between chromium(III) and polyacrylamide (PAAm) that leads to the crosslinking or gelation of the polymer. Cr(III) was added directly to solutions of polyacrylamide which had a degree of hydrolysis of approximately 4%. The unreacted Cr(III) was se…
Abstract The study of certain radioluminescence characteristics of stilbene single crystals is performed. Doping the stilbene melt with electron‐seeking (ES) addition agents of benzol and benzophenone halogen derivatives allowed to control the structure perfection of the crystal grown. The root‐mean‐square random orie…
High-resolution heat-capacity measurements have been made on mixtures of alkylphenyl-cyanobenzoyloxy benzoate (${\mathrm{DB}}_{\mathrm{n}}$CN) and cyanobenzoyloxypentyl stilbene (${\mathrm{C}}_{5}$stilbene). The mixtures ${\mathrm{DB}}_{5}$CN+${\mathrm{C}}_{5}$stilbene (with mole fraction of ${\mathrm{C}}_{5}$stilbene…