Materials Literature
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Clinically available synthetic ePTFE vascular grafts frequently fail when used for small-diameter arterial substitution. The lower long-term patency of ePTFE grafts is due mainly to thrombogenicity and poor healing. We developed a new small-diameter (1.5-mm) ePTFE vascular prosthesis coated with polyamino-acid urethan…
Abstract The use of biodegradable polymer films for mulching is a topic of great interest both from the environmental point of view and for the intrinsic properties that the above films, when appropriately designed, might have. In the present article we report on a synthetic approach that, starting from existing biode…
Abstract In this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation…
Neutron powder diffraction measurements on ${\mathrm{Ca}}_{2}{\mathrm{FeReO}}_{6}$ reveal that this double perovskite orders ferrimagnetically and shows anomalous lattice parameter behavior below ${T}_{C}=521\mathrm{K}.$ Below $\ensuremath{\sim}300\mathrm{K}$ and $\ensuremath{\sim}160\mathrm{K}$ we observe that the hi…
Recent experiments have identified three-layer and four-layer distorted helical structures in the smectic liquid-crystal phases Sm C*(FI1) and Sm C*(FI2), respectively. However, no theories have explained the existence of all these phases. A discrete phenomenological model of the free-energy is analyzed and found to p…
HiPco single-walled carbon nanotubes (HPNTs) containing Fe were purified by a one-step process with HCl-washing (D-method) and a two-step process with HCl-washing after air oxidation (GD-method). The HPNT samples before and after purification were characterized using the N 2 adsorption at 77 K, thermogravimetric analy…
The random discontinuous fiber composite has uniform properties in all directions. The wetlay process is an efficient method to manufacture random discontinuous thermoplastic preform sheets that can be molded into random composite plaques in the hot-press. Investigations were done on the molding parameters that includ…
Charge transport and magnetic properties of films of polyaniline (PAN) doped with 10-camphorsulfonic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) have been studied by conductivity, magnetic-susceptibility superconducting quantum interference device measurements, and 3-cm and 8-mm electron paramagnetic…
Dihydroxy-functionalized zwitterionic push−pull chromophores have been synthesized and incorporated into 3-glycidoxypropyltrimethoxysilane- and N -[(3-trimethoxysilyl)propyl]ethylenediamine-derived hybrid materials. The functionalization allowed the dye to form covalent bonds to the matrix network, reaching up to 5% m…
Mass transfer in micro- and mesoporous materials is of crucial importance in their practical application for separation and catalysis, since the mobility of adsorbed molecules ultimately limits the rate of the overall processes. Diffusion, i.e. the irregular thermal motion of the molecules, is the dominating process.…
The oriented-gas model based on the additivity hypothesis is widely used in predicting the macroscopic nonlinear optical susceptibility of a molecular crystal from molecular (hyper)polarizability calculations. Here, we argue that the intermolecular hydrogen bond interactions will break the additivity relationship for…
Abstract Seven dicarboxylates of calcium were synthesized. The effect of dicarboxylate on the formation of β‐form polypropylene was investigated by X‐ray diffraction. Calcium pimelate, calcium suberate, calcium phthalate, and calcium terephthalate have been found to be an effective β‐nucleator. The K x values of the i…
Abstract The influence of a nonpigmenting β‐nucleating additive in the crystallization of isotactic polypropylene (iPP) is investigated by differential scanning calorimetry and X‐ray diffraction. It is found that this additive induces the formation of a very high level of the trigonal modification of iPP. The crystall…
In this paper we simulate the resistive heating of carbon nanotubes (CNT's) during field emission (FE) using the one-dimensional heat equation including radiation and conductive losses. The simulations are in relatively good agreement with our recent experiments in which we measured the heating of individual CNT's to…
Brittle fracture in silicon is simulated with molecular dynamics utilizing a modified embedded atom method potential. The simulations produce propagating crack speeds that are in agreement with previous experimental results over a large range of fracture energy. The dynamic fracture toughness is found to be equal to t…
Applying the novel exact-exchange (EXX) Kohn-Sham method within time-dependent density-functional theory, we obtained the optical absorption spectrum of bulk silicon in good agreement with experiments including excitonic features. Analysis of the EXX kernel shows that inclusion of the Coulomb coupling of electron-hole…
A new achiral banana-shaped mesogen is presented which exhibits a nematic phase and an isotropic mesomorphic phase with spontaneous chiral ordering.
The study of quantum phase transitions, which are zero-temperature phase transitions between distinct states of matter, is of current interest in research since it allows for a description of low-temperature properties based on universal relations. Here we show that the crystal green dioptase Cu_6Si_6O_18 . 6H_2O, kno…
Experimental data obtained for PbFe$_{1 / 2}$Ta$_{1 / 2}$O$_{3}$ (PFT) and NaNbO$_{3}$: Gd (NaNbGd) single crystals show a diffused dielectric permittivity peak that is inherent to relaxor ferroelectrics. However some deviations from the normal relaxor properties were also observed and are under discussion. One of the…
We determine the effective dipolar interaction between single domain two-dimensional ferromagnetic particles (islands or dots), taking into account their finite size. The first correction term decays as 1/D^5, where D is the distance between particles. If the particles are arranged in a regular two-dimensional array a…