Materials Literature
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Luminescence properties of nanosized zinc oxide (ZnO) colloids greatly depend on their surface properties. These surface properties in turn are largely determined by the method of preparation. The procedure for producing ZnO colloids consists of two major steps: (1) preparing the precursor by reacting zinc acetate wit…
A family of mesoporous molecular sieves (denoted MSU-G) with vesiclelike hierarchical structures and unprecedented thermal (1000 degreesC) and hydrothermal stabilities (more than 150 hours at 100 degreesC) associated with high SiO4 cross-linking was prepared through a supramolecular assembly pathway that relies on hyd…
The tautomeric exchange of the inner hydrogens of free base alkylporphycenes was examined with the help of 13 C-CPMAS and 15 N-CPMAS NMR recorded at variable temperatures. The porphycenes used were octaethylporphycene 2, 2,7,12,17-tetrapropylporphycene 3, and 9,10,19,20-tetrapropylporphycene 4 . The CPMAS spectra reve…
The permeation of five volatile organic compounds found in Iberian ham aroma ( n -hexanal, n -hexanol, n -decane, ethyl caproate, and d -limonene) through films of ultra-low-density polyethylene (ULDPE) and two metallocene copolymers was evaluated at 23 °C. Values of the diffusion, permeability, and solubility coeffic…
The influence of chloride adsorption and lead upd on the step dynamics of Cu(100) has been examined in acid perchlorate solution. A c (2 × 2) Cl adlayer is formed upon immersion of a Cu(100) electrode leading to step faceting in the 〈100〉 direction. At more negative potentials an order−disorder transformation occurs l…
Principles of Radiation Physics Rationale Brief History of Radiation Science Matter and Energy Atomic Structure and Radioactivity Particle Interactions Gamma Ray Interactions Gamma Ray Interactions with Lead and Water Units of Radiation Exposure and Dose Rationale Basic Concepts Other Concepts Specific Gamma Constant…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTMixed Orientation State Induced by Expansion Flow of a Thermotropic Liquid-Crystalline PolymerDavid K. Cinader and Wesley R. BurghardtView Author Information Department of Chemical Engineering, Northwestern University, Evanston, Ill…
Novel aryl derivatives of benzamidine were synthesized and tested for their inhibitory potency against bovine trypsin, rat skin tryptase, human recombinant granzyme A, human thrombin, and human plasma kallikrein. All compounds show competitive inhibition against these proteases with Ki values in the micromolar range.…
The influences of various physical and chemical characteristics of solid substrates on apparent slip violations in entangled polybutadienes are investigated in plane-Couette shear flow. Slip measurements are reported for a range of substrates: (i) clean silica glass, (ii) uncleaned silica glass, (iii) fluorocarbon-coa…
A new synthetic strategy has been developed to introduce bent and rigid tridentate 2,6-bis(benzimidazol-2‘-yl)pyridine cores into rodlike ligands L 11 - 17 . The crystal structure of the nonmesogenic ligand L 13 (C 39 H 37 N 5 O 4, triclinic, P 1̄, Z = 2) shows the expected trans − trans conformation of the tridentate…
The translational diffusion of two small molecule probes, decacyclene and lophine, has been studied in supported polymer films as a function of film thickness using fluorescence nonradiative energy transfer. These probes are sufficiently large that their translational motion is coupled substantially to the segmental m…
The global kinetics of the reactions occurring during the selective catalytic reduction (SCR) of NO by NH 3 over vanadia-based commercial DeNO x catalysts has been studied. The global kinetic model developed accounts for three chemical reaction pathways (Eley−Rideal and Langmuir−Hinshelwood type SCR and ammonia oxidat…
From the leaves of Stenochlaena palustris five new O-acylated flavonol glycosides, stenopalustrosides A-E (1-5), have been isolated along with five known compounds, kaempferol 3-O-(3' '-O-E-p-coumaroyl)-(6' '-O-E-feruloyl)-beta-D-glucopyranoside (6), kaempferol 3-O-(3' ',6' '-di-O-E-p-coumaroyl)-beta-D-glucopyranoside…
Calculations of the A_1 phonon frequency in photoexcited tellurium are presented. The phonon frequency as a function of photoexcited carrier density and phonon amplitude is determined. Recent pump probe experiments are interpreted in the light of these calculatons. It is proposed that, in conjunction with measurements…
The microstructure of Bombyx mori silk fibers before and after degumming was examined by transmission electron microscopy (TEM), selected area electron diffraction (SAED), wide-angle X-ray scattering (WAXS), and low-voltage high-resolution scanning electron microscopy (LVHRSEM). LVHRSEM micrographs of the neat cocoon…
A novel two-step silica-coating process, sol−gel followed by dense liquid coatings, is described. The maghemite surfaces coated with silica, using the two-step process, are characterized by X-ray photoelectron spectroscopy, electrokinetics, leaching test, and magnetization measurement. Compared with the single-step so…
The synthesis and characterization of palladium-grafted mesoporous MCM-41 material, designated Pd-TMS11, are described. The material is investigated for carbon−carbon coupling reactions (Heck catalysis) with activated and nonactivated aryl substrates. For the preparation of the new catalyst, a volatile organometallic…
Experimental measurements, interpreted with mean field theories, provide quantitative understanding of the stability of colloidal particles coated with a highly asymmetric diblock copolymer. Adsorption of poly((dimethylamino)ethyl methacrylate)/poly( n -butyl methacrylate) onto colloidal silica particles from 2-propan…
Fine-line electronic absorption and fluorescence spectra of porphycene and 2,7,12,17-tetra- n -propylporphycene have been measured in low-temperature nitrogen, argon, krypton, and xenon matrices. A well-resolved emission spectrum of porphycene was also obtained in an isotropic glassy matrix using the fluorescence line…
The synthesis and liquid-crystalline properties of tetracatenar covalent and H-bonded bis-ferrocene derivatives 1 and 2, respectively, are reported. Both compounds gave rise to enantiotropic columnar liquid-crystalline behavior with a hexagonal molecular organization. To explore the possibility to obtain also calamiti…