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The size of Pt particles introduced into the channels of ZSM-5 zeolite by two different preparation methods has been studied\nwith EXAFS. ZSM-5 was loaded with 2 wt 5% Pt by ion exchange and by impregnation. By careful calcination of the catalysts\nthe dispersion was maintained. The EXAFS measurements were performed o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies of third-order optical nonlinearities of model compounds containing benzothiazole, benzimidazole and benzoxazole unitsMingtang Zhao, Marek Samoc, Paras N. Prasad, Bruce A. Reinhardt, Marilyn R. Unroe, Mark Prazak, Robert C. Evers, James J. Kane, Chetan Jariwala, and…
The performance of miniaturized electron optical systems comprising a field emission microsource and a microlens for probe forming has been studied. A complete system measuring millimeters in length and diameter with performance exceeding that of a conventional system over a wide range of potentials (100 V–10 kV) and…
We derive the phase diffusion and mean drift equations for the Oberbeck–Boussinesq equations in large-aspect-ratio containers. We are able to recover all the long-wave instability boundaries (Eckhaus, zigzag, skew-varicose) of straight parallel rolls found previously by Busse and his colleagues. Moreover, the developm…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRedox properties of porphycenes and metalloporphycenes as compared with porphyrinsJean Paul Gisselbrecht, Maurice Gross, Matthias Koecher, Michael Lausmann, and Emanuel VogelCite this: J. Am. Chem. Soc. 1990, 112, 23, 8618–8620Publication Date (Print):November 1, 1990Publica…
Ferroelectric liquid crystalline (LC) polymers (see figure), which in the smectic C* phase exhibit the highest yet known spontaneous polarization for LC polymers of up to 430 nC/cm 2 , a value which approaches that of the best low molecular weight materials, have been synthesized, based on chiral polysiloxanes. A copo…
Abstract Iron and manganese tetramethylporphine (TMP) complexes were synthesized within the cages in NaY zeolite. The ligation of porphine to the metals enhanced the capability of ion-exchanged zeolite to oxidize saturated hydrocarbons with hydrogen peroxide.
The formation of the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine, from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione requires a phosphorylated 4-carbon intermediate which has been designated as Compound X (Neuberger, G., and Bacher, A. (1985) Biochem. Biophys. Res. Commun. 127, 175-181). The enzyme cataly…
This paper is an overview of studies performed at the IBM Thomas J. Watson Research Center on diamondlike carbon (hydrogenated amorphous carbon) films, including some recent results on their tribological properties. The films were prepared by rf plasma-assisted chemical vapor deposition (PACVD) from acetylene. Their s…
An intense source of positive, negative, and neutral carbon clusters using excimer laser ablation of polyimide is described. The detection probability for large masses using a standard channel plate configuration is shown to increase exponentially with ion velocity. The large clusters are formed via aggregation of ato…
Total-energy band calculations using the local-spin-density approximation, the augmented-spherical-wave method, and the fixed-spin-moment procedure are used to investigate the volume dependence of the magnetic and electronic properties of 3d transition metals constrained to cubic environments in one-atom or two-atom u…
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We report a determination of the temperature dependence of the upper critical magnetic fields ${\mathit{H}}_{\mathit{c}2}$ for \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$Cu[N(CN${)}_{2}$]Br, with the use of dc-magnetization measurements that show a well-defined diamagnetic onset. We find large slopes of -20 T/K and -2.2 T/…
Bovine myelin basic protein (MBP) was found to be an excellent in vitro substrate (apparent Km = 50 microM) for MAP (mitogen-activated protein) kinase and can be used in lieu of microtubule-associated protein 2 for purification and functional studies of the enzyme. MBP phosphotransferase activity co-purified with MAP…
Abstract 1. For unswollen vulcanizates, storage modulus ( E ′) decreases with the increase in temperature and decrease in loading and surface area of carbon-black filler. On partial swelling, these effects are much reduced, and E ′ becomes independent of surface area and loading on equilibrium swelling. 2. Loss modulu…
Exchangeable Al in subsoils of Ultisols in the southeastern USA can restrict rooting depth. Downward movement of basic cations (Ca, Mg, and K), applied as lime and fertilizer, may diminish that restriction over time. Materials from the argillic horizon were collected from three paired sites, having managed (long-term…
Abstract Imidization of polyamic acid prepared from pyromellitic dianhydride and 4,4′‐methylenedianiline was investigated at 373–493 K. At a certain degree of imidization, depending on the reaction temperature, the reaction is significantly slowed down. For this reason, imidization was divided into two phases, a fast…
A mathematical model for forced‐flow chemical vapor infiltration (CVI) for densification of porous ceramic composites is presented. The process consists of mass transport of reactants by both convection and diffusion into a porous preform, decomposition of reactants, and subsequent deposition of solid product on pore…
The ferromagnetic Heusler alloy Pd2MnSn shows large reduction in magnetization by cold working, without any appreciable change in the Curie temperature. In order to clarify the relationship between the reduction and the defect structure in Pd2MnSn, transmission electron microscopic observation, high-resolution neutron…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of electrically conducting indium-tin-oxide thin films by heat treatment of mixed-metal hydroxide dispersion containing polymer binderTakaki Kanbara, Masayuki Nagasaka, and Takakazu YamamotoCite this: Chem. Mater. 1990, 2, 6, 643–645Publication Date (Print):Novem…