Materials Literature
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Passivated and unpassivated Al single-crystal lines with (110), (133), and (111) planes parallel to the substrate have been fabricated and electromigration tests have been performed to study transgranular failure mechanisms. Both erosion voids and slitlike voids with {111} facets were observed in single-crystal lines.…
Abstract The structural collapse of mesoporous molecular sieves MCM-48 and MCM-41 materials by mechanical compression was found to occur mechanochemically through the hydrolysis of Si-O-Si bonds. Their ordered structures were well retained by compressing the samples under dry N2.
A novel method of determining the cell thickness and the twist angle of twisted nematic liquid crystal (TNLC) cells by measurement of the Stokes parameters of light transmitted through the cell is presented. The relationships of the Stokes parameters of transmission light to the cell thickness and the twist angle are…
A stochastic model for localized corrosion is investigated both analytically and numerically. A feature of the model is that each metastable pitting event can influence subsequent events, although the influence of an individual event decays with time. The model describes an abrupt, cooperative transition from metastab…
Thin sol−gel films including rhodamine B (RB) which were dip-coated using the sol−gel reaction of tetraethyl orthosilicate have been prepared as a function of time after mixing of the reaction systems. The absorption and fluorescence spectra of the individual thin films have been observed as a function of time after t…
Eight amorphous polyethers and poly(ether ketones) were synthesized and characterized by gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical thermal analysis. Polymers containing bulky, cyclic 2,2‘-biphenyl side groups were found to have the highest glas…
Collagen-based implants have been described as vehicles for transplantation of cultured skin cells for treatment of burn wounds. To optimize vascularization and repair of connective tissue, collagen solubility and glutaraldehyde crosslinking were evaluated. Cultured skin substitutes consisted of human keratinocytes an…
The synthesis and mesogenic properties of a new class of liquid crystalline metal-free and metalated phthalocyanines with different numbers of alkylthio side chains are presented. The effect of the substitution pattern in a series of differently octasubstituted phthalocyanines on the width and order of the thermotropi…
The efficiency of the nonhydrolytic sol−gel process based on the condensation between metal chlorides and metal alkoxides has been studied in the preparation of aluminum titanate gels. Solutions of aluminum and titanium precursors in the ratio Al/Ti = 2 gave gels with the same metal ratio. The structural evolution of…
Random porous silicon dielectric multilayers are proposed as interesting materials for applications as optical components. Distributed Bragg reflectors and interferential Fabry - Pérot filters are demonstrated. The randomness is obtained as a variation in the layer thicknesses. The advantage in the use of random inste…
Abstract Surface barriers, designed to limit recharge and biointrusion, have been identified as a critical component in long‐term management of buried wastes. However, surface barrier technology remains largely unproven at the field scale. Recently, a prototype of a field‐scale (2.5 ha), vegetated, capillary surface b…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStopped-Flow Photo-CIDNP Observation of Protein FoldingP. J. Hore, Stephen L. Winder, Claire H. Roberts, and Christopher M. DobsonView Author Information Oxford Centre for Molecular Sciences Physical and Theoretical Chemistry Laboratory and New Chemistry Laboratory, Un…
We have used magic‐angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy to examine the polyhedral arrangements in ternary lanthanum aluminoborate glasses. We have characterized two glass‐forming series: x Al 2 O 3 ·(1− x )LaB 3 O 6 and 0.25La 2 O 3 · y Al 2 O 3 (1− y )‐B 2 O 3 . 11 B MAS NMR reve…
Cellulose and its chemical analogs chitin and chitosan are abundant and technologically important fibrous polysaccharides. Cellulose and chitin are, respectively, the first [1] and second [2] most abundant natural polysaccharides. Chitosan, though less prevalent in nature, is a useful and easily accessible derivative…
ZrW2O8 has a negative coefficient of thermal expansion from 0.3 K to its decomposition temperature around 1050 K. The negative thermal expansion is isotropic and is not disrupted by the structural phase transition at 430 K. A complicated distribution in reciprocal space of Rigid Unit Mode (RUM) phonons has been found…
We have carried out a femtosecond transient absorption spectroscopic study on nickel(II) porphyrins in various solvents in order to obtain detailed information on vibrational relaxation processes occurring in the initial stage after photoexcitation to the highly excited states. We found the decay process of time const…
The interactions between molecules of a low molecular weight diblock copolymer of poly(ethylene oxide) (E) and poly(butylene oxide) (B), B 8 E 41, at hydrophobic surfaces were investigated experimentally by using two surface force techniques and ellipsometry. Extended mean-field theory was employed to describe the ads…
The Pt-catalyzed reduction of NO by propene exhibits strong electrochemical promotion by spillover Na supplied from a β‘‘-alumina solid electrolyte. In the promoted regime, rate increases by an order of magnitude are achievable. At sufficiently high loadings of Na the system exhibits poisoning, and excursions between…
A new approach for designing optically switchable molecular communication devices based on spin-exchange interactions is proposed in the present paper. The device is constituted from two parts, i.e., a paramagnetic block (PMB) and a coupling control block (CCB). As a prototype of this model, nickel nitroprusside, Ni[F…
Quantities for Dosimetry of Ionizing Radiations in Liquid Water , Quantities for Dosimetry of Ionizing Radiations in Liquid Water , کتابخانه الکترونیک و دیجیتال - آذرسا