Materials Literature
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Abstract A mechanistic study of the trans⇆cis isomerization of the azobenzene moiety in a side‐chain liquid‐crystal polymer system was carried out with six liquid‐crystalline polymethacrylates in which different electron‐withdrawing substituents were attached to the para‐positions of the azobenzene chromophores. Compa…
Na- and Ca-exchanged smectite in aqueous suspension have been studied using the polarized attenuated total reflectance (ATR)-FTIR technique. These spectra correspond to the first reported use of polarization methods to study smectite particles in aqueous suspension. Similar to the behavior of hydrous metal oxides, a t…
We calculate ab initio the NMR relaxation rates and the Knight shifts in MgB_2. We show that the dominant relaxation mechanism at the B nucleus is the interaction with the electronic orbital moment, and we give a simple explanation of that using a simple $sp$ tight binding model. When Stoner enhancement (also calculat…
The transverse magnetoresistance of the Bechgaard salt (TMTSF)$_2$PF$_6$ has been measured for various pressures, with the field up to 24 T parallel to the lowest conductivity direction c$^{\ast}$. A quadratic behavior is observed in the magnetic field dependence of the spin-density-wave (SDW) transition temperature $…
The possibility to induce ferromagnetism and insulator to metal transitions in small A site cation manganites Ln_{1-x}Ca_xMnO_3 by rhodium doping is shown for the first time. Colossal magnetoresistance (CMR) properties are evidenced for a large compositional range (0.35 \leq x < 0.60). The ability of rhodium to induce…
We present a detailed study of the exchange-correlation hole and exchange-correlation energy per particle in the Si crystal as calculated by the Variational Monte Carlo method and predicted by various density functional models. Nonlocal density averaging methods prove to be successful in correcting severe errors in th…
The reaction of LiGaMe 4 with diphenysilanediol in THF at 50 °C leads to the formation of the title gallosiloxane Li 2 (Li(THF) 2 ) 2 [Ph 2 SiO 2 GaMe 2 ] 2 [Ph 2 SiO 2 GaMe(OH)] 2 ·2THF ( 1 ), which is made up of a central tetraanionic Ga 4 Si 4 O 8 16-membered macrocyclic core. The cavity that is created by this tet…
A novel synthesis of 3-fold symmetric, homochiral tris(2-alkyl-2-aminoethyl)amine (TREN) derivatives is presented. The synthesis is general in scope, starting from readily prepared chiral alpha-amino aldehydes. The optical purity of the N-BOC protected derivatives of tris(2-methyl-2-aminoethyl)amine and tris(2-hydroxy…
Delta5-3-ketosteroid isomerase (KSI) from Pseudomonas putida Biotype B catalyzes the allylic isomerization of Delta5-3-ketosteroids to their conjugated Delta4-isomers via a dienolate intermediate. Two electrophilic catalysts, Tyr-14 and Asp-99, are involved in a hydrogen bond network that comprises Asp-99 Odelta2...O…
Abstract A series of poly( o ‐hydroxy amide)s having both ether and sulfone linkages in the main chain were synthesized via the low‐temperature solution polycondensation of 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoyl chloride and 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoyl chloride with three bis(…
The dynamics and thermodynamics of a model potential-energy surface are analyzed with regard to supercooling and glass formation. Relaxation is assumed to be mediated by pathways that connect groups of local minima. The dynamics between these groups is treated via transition state theory using appropriate densities of…
Part 1 of these studies described poly(methyl methacrylate-r-polyoxyethylene methacrylate) P(MMA-r-POEM) comb polymers that present Arg-Gly-Asp (RGD) peptides at a surface in nanoscale clusters on a protein-resistant background for control of cell adhesion. Here in part 2, we examine surface segregation of these pepti…
Variable-temperature single-crystal X-ray diffraction using a synchrotron X-ray source has allowed the mechanism of negative thermal expansion in the pure silica zeolite IFR to be studied in greater detail than was previously possible over the temperature range 30-557 K. The results have allowed the changes in average…
An incident fast ion in the electronic stopping regime produces a track of excitations which can lead to particle ejection and cratering. Molecular Dynamics simulations of the evolution of the deposited energy were used to study the resulting crater morphology as a function of the excitation density in a cylindrical t…
The dispersion of the A-valence-band in GaN has been deduced from the observation of high-index magneto-excitonic states in polarised interband magneto-reflectivity and is found to be strongly non-parabolic with a mass in the range 1.2-1.8 m_{e}. It matches the theory of Kim et al. [Phys. Rev. B 56, 7363 (1997)] extre…
Conjugates of bovine serum albumin and CdTe nanoparticles capped with l -cysteine have been synthesized via a one-pot glutaric dialdehyde cross-linking procedure. Diads (1:1) with some amount of 2:1 albumin−nanoparticle assemblies preferably form in this reaction, as evidenced by gel electrophoresis. Circular dichrois…
The crystal structure of the title compound, [Fe(C(44)H(20)F(8)N(4))(CH(3)O)], has been determined. The Fe atom lies 0.485 (1) A out of the plane of the four N atoms to which it is coordinated and from the inversion centre at the origin of the unit cell. The methoxy group is axially coordinated to the Fe atom with O-F…
Single stage thin film coolers based on thermoelectric and thermionic cooling in p-type InGaAsP superlattice structures have been fabricated. Devices with different sizes and at various ambient temperatures have been characterized. Experimental results showed 0.5 degree centigrade cooling below the ambient temperature…
Significant progress has been made in the last decade in understanding mixtures of hard–sphere colloids and (smaller) non–adsorbing, ideal, linear polymers. We introduce extra complexity into this simple model system by replacing the linear polymers with star–branched polymers with increasing functionality but constan…
In situ monitoring of catalyst nickel atoms by laser induced fluorescence during carbon nanotube formation in a laser-produced plume was performed at the Johnson Space Center nanotube production laboratory. The results indicate that ablation of nickel and plume dynamics are strongly related to the oven temperature. Ni…