Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We have developed a new technique to measure viscoelasticity in soft materials such as polymer solutions, by monitoring thermal fluctuations of embedded probe particles using laser interferometry in a microscope. Interferometry allows us to obtain power spectra of fluctuating beads from 0.1 Hz to 20 kHz, and with sub-…
A theory of the hysteresis loop in ferromagnets controlled by the domain wall motion is presented. Domain walls are considered as plane or linear interfaces moving in a random medium under the action of the external ac magnetic field $H=H_0\sinωt$. We introduce important characteristics of the hysteresis loop, such as…
PE and PBT are known to be incompatible polymers. A grafted copolymer PBT-EVA has been generated as a compatibilizer in situ during the processing operation by redistributive transesterification between PBT and EVA in the presence of dibutyl tin oxide (DBTO). This copolymer has been isolated by selective extractions f…
Hybrid systems based on 3-trimethoxysilyl propyl methacrylate, tetramethylorthosilicate, and methyl methacrylate were developed for moisture protection and strengthening of glass objects. The hydrophobic behavior of the hybrid was obtained by adding different fluorinated precursors to the hybrid solution. Experimental…
In his Perspective, Engel discusses the diverse structural features of collagens, a ubiquitous fibrillar protein that forms the main support of skin and tendons. A unique example is reported in this issue by Coyne et al ., who describe the amino acid sequence of the specialized collagen that forms the byssal threads t…
To adhere to solid surfaces, marine mussels produce byssal threads, each of which is a stiff tether at one end and a shock absorber with 160 percent extensibility at the other end. The elastic extensibility of proximal byssus is extraordinary given its construction of collagen and the limited extension (less than 10 p…
The fcc-based structure of Yb2.75C60 is unique among metal-doped fullerene compounds, exhibiting long-range-ordered vacancies, significantly off-centered divalent Yb cations, and distorted, crystallographically inequivalent, orientationally ordered C60 anions. A simple electrostatic-energy analysis, which models the c…
The reversible reaction of a monomeric CuII complex to a cyclic hexamer (crystal structures shown below) is the first example interconversion between a potential guest complex and a complex that cannot function as a guest [Eq. (a)]. It is—like in living organisms—controlled by a very common external signal, namely pro…
Why don't we live in β-peptide world? This is a legitimate question in light of new findings by D. Seebach et al. and S. Gellman et al. on the secondary structures of β-peptides. Peptides composed of less than ten β-amino acid residues can from stable, secondary structure motifs like the 31-M-helix shown on the right.…
A highly ordered lamellar mesophase is exhibited by the thermally stable liquid-crystalline gold(I) dicarbene compounds presented here. The crystal structure of one of these compounds is depicted on the right.
The total energy differences between various SiC polytypes (3C, 6H, 4H, 2H, 15R and 9R) were calculated using the full-potential linear muffin-tin orbital method using the Perdew-Wang-(91) generalized gradient approximation to the exchange-correlation functional in the density functional method. Numerical convergence…
Improvement of a superconducting magnet system makes induction of a strong magnetic field easier. This fact gives us a possibility of energy conversion by the Nernst effect. As the first step to study the Nernst element, we measured the conductivity, the Hall coefficient, the thermoelectric power and the Nernst coeffi…
The statistical properties of coherent radiation scattered from phase-ordering materials are studied in detail using large-scale computer simulations and analytic arguments. Specifically, we consider a two-dimensional model with a nonconserved, scalar order parameter (Model A), quenched through an order-disorder trans…
A LMTO implementation of Aversa and Sipe's length-gauge formalism for calculating the full frequency dependent second-harmonic generation in the independent particle approximation is presented. It is applied to GaAs, GaP, 3C-SiC, c-BN and wurtzite and zincblende GaN and AlN. The use of the scissor's operator for corre…
Double exchange (DE), superexchange (SE), and higher-order contributions to the exchange interaction energy between Mn layers in ${\mathrm{LaMnO}}_{3}$ are studied using the linear-muffin-tin-orbital method as generalized to treat noncollinear magnetic configurations. The degree of the internal lattice distortion $(f)…
Photocurrent changes with light soaking have been studied in amorphous ${\mathrm{As}}_{2}{\mathrm{S}(\mathrm{S}\mathrm{e},\mathrm{T}\mathrm{e})}_{3}$ and Se and crystalline ${\mathrm{As}}_{2}{\mathrm{S}}_{3}$ and Se at 10--300 K. In the chalcogenide glasses the photoconductive degradation occurs at 300 K, while at low…
Heat-capacity and magnetic-susceptibility studies have been carried out on ${\mathrm{NiS}}_{2\ensuremath{-}x}{\mathrm{Se}}_{x}$ single crystals for $0.38<~x<~0.58$ and $0<~x<~0.71,$ respectively. These and earlier physical measurements document the gradual evolution, with rising $x,$ of the alloys from goo…
We applied molecular dynamics, density functional theory, and computer graphics techniques to the investigation of the homoepitaxial growth process of the MgO(001) surface. MgO molecules are deposited over the MgO(001) plane one by one at regular time intervals with definite velocities. Any deposited MgO molecule migr…
Two ether-sulfone-dicarboxylic acids, 4,4′-[sulfonylbis(2,6-dimethyl-1,4-phenylene)dioxy]dibenzoic acid (Me-III) and 4,4′-[sulfonylbis(1,4-phenylene)dioxy]-dibenzoic acid (III), were prepared by the fluorodisplacement of 4,4′-sulfonylbis(2,6-dimethylphenol) and 4,4′-sulfonyldiphenol with p-fluorobenzonitrile, and subs…
Copolyamides based on poly(m-phenylene isophthalamide) and poly-(p-phenylene terephthalamide), to which 1,6-diaminohexane units were regularly inserted every 3 or 5 phenylene monomer units, were synthesized. The copolymers were obtained by condensation of individually prepared diamino- and dicarboxylic-building blocks…