Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTEffect of an Internal Anthranilamide Turn Unit on the Structure and Conformational Stability of Helically Biased Intramolecularly Hydrogen-Bonded DendronsBaohua Huang and Jon R. ParquetteView Author Information Department of Chemistry The Ohio State University Columbus…
A new equation describing the behavior of the structural relaxation time, tau(T,P), as a function of both pressure and temperature, is discussed. This equation has been derived from the Adam-Gibbs theory by writing the configurational entropy, S(c), in terms of the excess thermal heat capacity and of the molar thermal…
We visualize undulations in layered systems using a cholesteric stripe phase with a macroscopic supramicron periodicity. The wave vector of stripe pattern is in the cell's plane. The undulation is induced by an in-plane magnetic field normal to the stripes. The observed displacement of layers is much larger than the v…
A method is suggested for the coating of micron-sized particles by polymeric films based on surface-controlled precipitation. Polymer particles were coated by dextran and DNA in a water/ethanol mixture containing multivalent cations. A theoretical model for depositing polymers on colloidal particles is presented using…
We investigate two-dimensional (2D) melting in the presence of a one-dimensional (1D) periodic potential as, for example, realized in recent experiments on 2D colloids subjected to two interfering laser beams. The topology of the phase diagram is found to depend primarily on two factors: the relative orientation of th…
Five generations of poly(propylene imine) dendrimers have been modified by palmityl and adamantyl endgroups via a thiourea linkage. The synthesis of the thiourea dendrimers DAB-dendr-(NHCSNHAd)(n) and DAB-dendr-(NHCSNHC(16)H(33))(n) (n = 4, 8, 16, 32, 64) proceeds smoothly via the amino-terminated DAB dendrimer and th…
The transport and relaxation properties of a molecular supercooled liquid on an isobar are studied by molecular dynamics. The molecule is a rigid heteronuclear biatomic system. The diffusivity is fitted over four orders of magnitude by the power law $D\ensuremath{\propto}(T\ensuremath{-}{T}_{c}{)}^{{\ensuremath{\gamma…
The rotational dynamics of a supercooled model liquid of rigid A-B dumbbells interacting via a Lennard-Jones potential is investigated along one single isobar. The time-temperature superposition principle, one key prediction of mode-coupling theory (MCT), was studied for the orientational correlation functions C(l). I…
Titanium-containing mesoporous molecular sieve Ti−MCM-41 has been synthesized using colloidal silica as the silicon source and TiCl 3 solution as the titanium source and was characterized by X-ray diffraction, N 2 adsorption, UV−vis, and UV−Raman spectroscopies. The formation of anatase TiO 2 can be avoided during the…
Mesoporous silica materials (MCM-41) were characterized by 13 C and 29 Si magic angle spinning (MAS) NMR. 13 C chemical shifts reveal a high content of gauche conformations in the chain of cationic surfactant molecules within the nanopores. 13 C T 1 's and proton to carbon cross-polarization times ( T CH ) demonstrate…
A statistical mechanical treatment is given of the confinement of a wormlike polymer in an entangled solution to a tube, yielding quantitative predictions for the average tube diameter D(e) and macroscopic plateau modulus G, in the tightly entangled regime in which D(e) is much less than the persistence length L(p). T…
The lattice parameters of MgB2 up to pressures of 8 GPa were determined using high-resolution x-ray powder diffraction in a diamond anvil cell. The bulk modulus, B0, was determined to be 151 +-5 GPa. Both experimental and first-principles calculations indicate nearly isotropic mechanical behavior under pressure. This…
Microprocessor powers are increasing at a phenomenal rate, which requires very small thermal resistance between the die (chip) and the ambient, if the current economical methods of conduction and convection cooling are to be utilized. A typical thermal solution in flip chip technology utilizes two levels of thermal in…
This work presents a step furthering a new perspective of proactive control of the spin-exciton dynamics in the quantum limit. Laser manipulation of spin-polarized optical excitations in a semiconductor nanodot is used to control the spin dynamics of two interacting excitons. Shaping of femtosecond laser pulses keeps…
We report on the ESR, magnetization and magnetic susceptibility measurements performed over a large temperature range, from 1.5 to 750 K, on high-quality stoichiometric LiNiO2. We find that this compound displays two distinct temperature regions where its magnetic behavior is anomalous. With the help of a statistical…
During the directional solidification of peritectic alloys, two stable solid phases (parent and peritectic) grow competitively into a metastable liquid phase of larger impurity content than either solid phase. When the parent or both solid phases are morphologically unstable, i.e., for a small temperature gradient/gro…
We examine in full generality the phase behavior of systems whose constituent particles interact by means of potentials that do not diverge at the origin, are free of attractive parts, and decay fast enough to zero as the interparticle separation r goes to infinity. By employing a mean field-density functional theory…
The preparation of substituted glycolides can greatly expand the pool of monomers available for the synthesis of polyglycolides, and provide a broader range of physical properties for degradable polymers. Ethyl-, hexyl-, isobutyl-, and benzylglycolide were prepared and converted to high molecular weight polymers by ri…
Unexpected high photoemission intensity is observed on copper surfaces at grazing incidence angles of p-polarized light $(\ensuremath{\Elzxh}\ensuremath{\omega}=21.2\mathrm{eV}).$ The dipole approximation in combination with Fresnel's equations and the optical constants of copper is not sufficient to explain the exper…
We here present a series of ab initio quantum-chemical calculations on clusters of atoms modeling several oxygen-deficiency-related defects in amorphous silica and illustrate how these defect centers will change their atomic configurations upon photoionization. We first give theoretical evidence that structural conver…