Materials Literature
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Abstract Graft copolymers of natural rubber (NR) and methyl methacrylate (MMA) were prepared using cumene hydroperoxide and tetraethylene pentamine as redox initiators via the semibatch emulsion polymerization technique. Various molar percentage ratios of NR/MMA were studied in the grafting reaction (i.e., 95/5, 90/10…
Abstract Copper chitosan complexes prepared by different specifications of chitosan and copper sulfate were used as urea sorbents. Experimental results showed that the adsorption capacity for urea of copper chitosan increased with an increasing degree of deacetylation and decreasing molecular weight of chitosan. The u…
In order to see the effect of CO(2) inhibition resulting from the use of pure oxygen, we carried out a comparative fed-batch culture study of polyhydroxybutyric acid (PHB) production by Ralstonia eutropha using air and pure oxygen in 5-L, 30-L, and 300-L fermentors. The final PHB concentrations obtained with pure O(2)…
We report Monte Carlo simulations of a lattice-polymer model that can account for both polymer crystallization and liquid–liquid demixing in solutions of semiflexible homopolymers. In our model, neighboring polymer segments can have isotropic interactions that affect demixing, and anisotropic interactions that are res…
The first goal of this article is to study the validity of the Zwanzig model for liquid crystals to predict transitions to inhomogeneous phases (like smectic and columnar) and the way polydispersity affects these transitions. The second goal is to analyze the extension of the Zwanzig model to a binary mixture of rods…
A diamond detector structure for uniform and efficient collection of photogenerated carriers in the ultraviolet spectral range is presented. The device operating principle is based on the contemporary collection of both photogenerated carriers in the bulk, and photoelectrons emitted from the diamond surface. A three-e…
Based on a simple two-level system, we discuss optical gain in materials with indirect optical transitions. We show that contrary to direct materials the absolute value of the negative absorption coefficient, which describes the optical gain, can be orders of magnitude larger in indirect semiconductors than the positi…
It is known from experiment that the light emission from a sonoluminescing bubble can be increased by using more than one driving frequency. In this paper, a systematic method to determine the optimal conditions of pressure amplitude and relative phase for this effect is described. As a specific application, a two-fre…
A nanosecond pulsed laser direct-write and doping (LDWD) technique is used for the fabrication of carbon-rich silicon carbide nanoribbons heterostructure in a single crystal 4H–SiC wafer. Characterization by high-resolution transmission electron microscope and selected area electron diffraction pattern revealed the pr…
Abstract For the first time, high‐percentage molybdosilicic acid fiber mats (20–80% H 4 SiMo 12 O 40 ) were prepared using the electrospinning technique. The fiber mats were characterized by IR, XRD, and DSC. The results indicated that poly(vinyl alcohol) was changed from a semicrystalline to an amorphous state with a…
During the deposition of films that grow by the Volmer–Weber mechanism, crystallites nucleate as isolated islands, grow larger to impinge with other islands, and eventually coalesce into a continuous film. Tensile stress generation due to grain boundary formation during island coalescence, commonly referred to as isla…
We give a brief review of how activation energies from scan-rate-dependent Tg studies have been correlated with those for viscosity and other relaxation processes, in order to place the present study in context with previous work, including that referred to in the comment. Then we examine the ensuing question of the e…
Cationic and anionic microgels based on sulfonated polystyrene and poly(ethylmethacryltetramethylammonium chloride) and containing Pd and Pt nanoparticles were used as templates along with polystyrene- block -poly(ethylene oxide) block copolymers for casting nanoporous alumina and aluminosilica with nanoparticles. The…
Using electron microscopy, we identify local, intergranular regions of hexagonal close-packing at a grain boundary in gold. By analyzing the topological defects that connect this layer to the adjacent face-centered cubic grains, we explain the geometric origin of this interfacial reconstruction. We extend this analysi…
Polyaniline (PANI) porous asymmetric membranes were prepared using a phase-inversion technique, and their bending−recovery behavior induced by sorption and desorption of chemical vapors was studied. It was found that the bending−recovery rates and maximum bending angles of the membranes were different in various vapor…
Behaviors of magnetic domains with cooling in a Ni51Fe22Ga27 ferromagnetic shape memory alloy were examined by electron holography and Lorentz microscopy. A peculiar meshy pattern was observed in the Lorentz microscope image of the parent phase, being concurrent with the anomaly in the thermomagnetization curve. The m…
This letter reports on flexible field emitter arrays of single-walled carbon nanotubes (SWNTs) aligned on organic polymer substrates. An array of gold electrodes was patterned on the Ti-coated polymer substrate by sputtering gold through a shadow mask. A self-assembly monolayer of organic molecules was then formed on…
Multiwall boron nitride nanotubes (BNNTs) were produced with a yield of about 50% by co-pyrolyzing NH 4 BF 4, KBH 4, and NaN 3 in a temperature range from 450 to 600 °C. The obtained BNNTs have a diameter range of 60−350 nm and length range of 0.5−5 μm. Many BN nanocages were found coexisting with the BNNTs. The exper…
Homogeneous ice nucleation was investigated in aqueous solutions of poly[ethylene glycol] (PEG) with a molar mass between 300 and 6000 g mol−1. Experiments were performed with a differential scanning calorimeter using emulsified aqueous PEG solutions with concentrations of 0–44 wt %. Equilibrium phase transition tempe…
Solid solutions of xBiFeO3–yPrFeO3–zPbTiO3 (x+y+z=1) and (1−w)BiFeO3–wPbTiO3 have been explored for finding ferroelectromagnetic bulk material, in which ferroelectricity and ferromagnetism coexist simultaneously. The coexistence has been observed only in some ternary composition samples, that is, 0.2BiFeO3–0.2PrFeO3–0…