Materials Literature
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We develop coarse-grained force fields for poly (vinyl alcohol) and poly (acrylic acid) oligomers. In both cases, one monomer is mapped onto a coarse-grained bead. The new force fields are designed to match structural properties such as radial distribution functions of various kinds derived by atomistic simulations of…
Using an efficient optimal control scheme to determine the exciting fields, we theoretically demonstrate the optical creation of vibrational intrinsic localized modes (ILMs) in anharmonic perfect lattices with realistic interatomic potentials. For systems with finite size, we show that ILMs can be excited directly by…
We have grown single crystals of electron doping system Ca2-xLaxRuO4 (0.00 <= x <= 0.20) by a floating zone method. The first order metal/non-metal transition and canted antiferromagnetic ordering occur for 0.00 < x < 0.15, similar to those in the bandwidth controlled system Ca2-xSrxRuO4 (CSRO). However, comparing wit…
The utilisation of crystalline semiconductor materials as detectors and devices operating in high radiation environments, at the future particle colliders, in space applications, in medicine and industry, makes necessary to obtain radiation harder materials. Diamond, SiC and different AIIIBV compounds (GaAs, GaP, InP,…
A simplified theoretical model for the constant-magnitude steady-state surface photovoltage (SPV) technique is developed. Emphasis is placed on the determination of the minority carrier diffusion length L in the particular case for which the sample thickness is quite lower than the true value of L. The model is derive…
The origin of ferroelectricity in KH_2PO_4 (KDP) is studied by first-principles electronic structure calculations. In the low-temperature phase, the collective off-center ordering of the protons is accompanied by an electronic charge delocalization from the "near" and localization at the "far" oxygen within the O-H...…
The magnetic behaviour of nanoparticles of antiferromagnetic ferritin has been investigated by 57Fe Mossbauer absorption spectroscopy and magnetisation measurements, in the temperature range 2.5K-250K and with magnetic fields up to 7T. Samples containing nanoparticles with an average number of Fe atoms ranging from 40…
Magnetic and magnetostrictive properties have been investigated for amorphous (Tb 0.27 Dy 0.73 )(Fe x Co 1- x ) 2 thin films. An increase in the 3d magnetic moment and Curie temperatures higher than 550 K due to the enhancement of T-T interactions (T = transition metal) in substituted (Fe, Co) alloys were found. A wel…
We report the electron transport studies in the rhombohedral LaMn 1- x Al x O 3+δ series (0⩽ x ⩽20%) of samples. Though all the samples are ferromagnetic below a transition temperature ( T C ), only the samples with x ⩽5% exhibit a metal-insulator transition (MIT) at T C while the samples with x ⩾10% are all semicondu…
The explosive charge within a landmine is the source for a mixture of chemical vapors that form a distinctive 'chemical signature' indicative of a landmine. The concentration of these compounds in the air over landmines is extremely low, well below the minimum detection limits of most field- portable chemical sensors.…
Nature tries to minimize the surface area of a soap film through the action of surface tension. The process can be understood mathematically by using differential geometry, complex analysis, and the calculus of variations. This book employs ingredients from each of these subjects to tell the mathematical story of soap…
Adsorption of hydrogen sulfide on fifteen samples of activated carbons (unmodified and catalytic with introduced basic nitrogen groups) was studied using inverse gas chromatography (IGC) at infinite dilution. Porous structure of carbons was evaluated using sorption of nitrogen. From the retention volume measured in IG…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTChemical Modification of Chitosan. 3. Hyperbranched Chitosan−Sialic Acid Dendrimer Hybrid with Tetraethylene Glycol SpacerHitoshi Sashiwa, Yoshihiro Shigemasa, and René RoyView Author Information Department of Chemistry, University…
In this paper, we examine collective and self-diffusion properties of dispersions of spherically shaped colloidal particles at intermediate and long times. Our analysis is based on a fully self-consistent (rescaled) mode coupling theory (MCT) adjusted to describe the overdamped dynamics in concentrated suspensions of…
The photoluminescence (PL) at 300 and 90 K from the mesoporous silicas (MSs) [ordered (MCM-41) and disordered (DMSs)] of variously sized pores induced either by ArF laser light (λ exc = 193 nm) or by Nd:YAG (yttrium−aluminum−garnet) laser light (λ exc = 266 nm) was studied. The spectra were measured in both convention…
Zinc porphyrin receptors bearing 12 ester groups in the meso phenyl groups (1-3) were prepared, and binding of amines and alpha-amino esters was studied with emphasis on the binding mechanisms. The X-ray crystallographic analysis of 5,10,15,20-tetrakis(2, 6-bis(carbomethoxymethoxy)-4-carbomethoxyphenyl)porphyrin (free…
Pyrolysis of hyperbranched poly[1,1‘-ferrocenylene(methyl)silyne] ( 5 ) yields mesoporous, conductive, and magnetic ceramics ( 6 ). Sintering at high temperatures (1000−1200 °C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in ∼48−62% yields. The ceramization yields of 5 are higher than that (∼36%) o…
A mechanism for the formation of polyelectrolyte multilayers is proposed. All of the experiments on such systems show that there is strong interpenetration of consecutive layers. We explain the very strong stability of the multilayers by the complexation between polyelectrolytes of opposite signs. Scaling laws on bulk…
State-of-the-art first principles calculations based on density functional theory were performed on CH_3(CH_2)_{n-1}S-Au(111) systems. We show that the adsorption site of methylthiolate at low coverage on the Au(111) surface is the fcc site, not the hcp site as has been recently reported. Further, we report results fo…
We study, both numerically and variationally, the interplay between different types of elementary excitations in the model of a spin chain with anisotropic spin-orbit coupling, in the vicinity of the "dimer line" with an exactly known dimerized ground state. Our variational treatment is found to be in a qualitative ag…