Materials Literature
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Both tri- and tetra(ethylene glycol) linked bis-chromium carbene complexes have been synthesized. These carbene complexes were photolyzed with N-protected imidazolines to give protected azapenams. These were transformed into polyether-linked basket dioxocyclams 4a,b and bis-dioxocyclams 5a,b. These compounds have cavi…
In this paper we first develop an approximate theory for the leading order concentration dependence of the sedimentation coefficient for rodlike colloids/polymers/macromolecules. To first order in volume fraction φ of rods, the sedimentation coefficient is written as 1+αφ. For large aspect ratios L/D (L is the rod len…
The synthesis of 3H-naphtho[2,1-b]pyrans linked to mono-, di-, or terthiophene via an acetylenic junction is described (Schemes 2 and 3). The synthetic approaches involve successive Sonogashira coupling reactions. The photochromic properties in solution of these novel materials were investigated under continuous irrad…
The adsorption mechanism of horse spleen apoferritin on smooth Si(Ti)O2 surfaces was investigated by means of optical wave guide lightmode spectroscopy (OWLS) as well as with atomic force microscopy (AFM), for which images of high resolution were obtained on muscovite mica surfaces. By the use of both experimental met…
In this work we present a simple model for the kinetics of spreading of film-forming liquids on polymer gels. The model is compared with experiments and fair agreement is obtained. The spreading process can be theorized by considering the gel as a thick liquid layer containing a fibrous material (i.e., the polymer net…
The wavelength dependent photochemical cross sections for three adsorbates (OCS, NO, SO2) on roughened silver have been measured, and contrasted with the behavior on Ag(111). Surface roughness leads to significant enhancements of the photochemical cross sections for all three adsorbates. The enhancement exhibits a max…
There is much literature showing that carbon black particles in vulcanized natural \nrubber modify the mobility of the polymer chains as a result of chemical linkages formed \nbet\\veen the two materials. This modified polymer layer is estimated to be about 50 A in \nthickness. Therefore. the modulus and the ultimate…
Some deciduous hardwoods such as oak or elm have very large vessels concentrated \nat the beginning of annual rings. Such woods are called &s;"ring porous wood." whereas \nother deciduous species and almost all evergreen hardwoods in which the vessels arc \nevenly dispersed over the annual ring arc calJed "&s;diffuse…
The ground and excited electronic states conformations of various tautomers of salicylidene methylamine (SMA) are calculated by ab initio methods. It is demonstrated that the cis-keto form, more stable in the ππ* S1 state, can rapidly decay to a strongly nonplanar configuration of the nπ* state, which subsequently und…
Antioxidants colourants coupling agents fiber reinforcment fillers - types, properties and performance flame retardant and smoke suppressants heat stabilizers for halogenated polymers impact modifiers lubricants optical brighteners plasticizers processing aids specialty additives.
The remarkable rate enhancement of orotidine 5'-phosphate decarboxylase (ODCase) has been attributed to ground-state destabilization (GSD) by desolvation and more recently to GSD by electrostatic stress. Here we reiterate our previous arguments that the GSD mechanisms are not likely to play a major role in enzyme cata…
Classical and path integral molecular dynamics (PIMD) simulations are used to study alpha-quartz and beta-quartz in a large range of temperatures at zero external stress. PIMD account for quantum fluctuations of atomic vibrations, which can modify material properties at temperatures below the Debye temperature. The di…
We observed room-temperature intersubband transitions at 1.26 microns in n-doped type-II In$_{0.3}$Ga$_{0.7}$As/AlAs strained quantum wells. An improved tight-binding model was used to optimize the structure parameters in order to obtain the shortest wavelength intersubband transition ever achieved in a semiconductor…
The dependence of mesoscopic conductance fluctuations on parallel magnetic field is used as a probe of spin degeneracy in open GaAs quantum dots. The variance of fluctuations at high parallel field is reduced from the low-field variance (with broken time-reversal symmetry) by factors ranging from roughly two in a 1 sq…
Background —Tissue engineering using in vitro–cultivated autologous vascular wall cells is a new approach to biological heart valve replacement. In the present study, we analyzed a new concept to process allogenic acellular matrix scaffolds of pulmonary heart valves after in vitro seeding with the use of autologous ce…
Classification of designs by symmetry group Classification of designs by symmetry group and design unit Classification of discrete patterns Classification of isohedral tilings.
A water-soluble self-doped conducting polypyrrole-based copolymer was synthesized via the grafting of pyrrole onto the p-aminodiphenylamine moieties of a water-soluble copolymer. The conductive copolymer exhibited a conductivity as large as 3.4 S/cm. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 86–89, 2001
Background —Tissue engineering is a new approach in which techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional autologous tissue. Workers at our laboratory have focused on tissue engineering of heart valves. The present study was designed to evalu…
Background —Previous tissue engineering approaches to create heart valves have been limited by the structural immaturity and mechanical properties of the valve constructs. This study used an in vitro pulse duplicator system to provide a biomimetic environment during tissue formation to yield more mature implantable he…
It is shown that, in submonolayer growth at off-normal incidence, even much less than one percent of transfer from the condensation energy of the deposited atoms into adatom motion is sufficient to induce a net adatom current from the illuminated edge of a two-dimensional island to the other edges, thereby breaking th…