Materials Literature
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Abstract Blends of isotactic polypropylene (PP), ethylene‐propylene rubber copolymer (EPR), and ethylene‐propylene crystalline copolymer (EPC) can be produced through in situ polymerization processes directly in the reactor and blends with different structure and composition can be obtained. In this work we studied th…
Abstract Nanocomposites were produced from cotton with montmorillonite clay used as the nanofiller material. Three exfoliation and intercalation methods with different solvents and clay pretreatment techniques were tested for the production of these organic–inorganic hybrids. The method that resulted in superior clay–…
Abstract Thermoplastic elastomers, prepared by melt blending of natural rubber (NR) and isotactic polypropylene (PP) through a dynamic vulcanization technique, were developed during the later 1970s. However, they have certain drawbacks due to thermal degradation and higher molecular weight of NR. In the study reported…
The thermal conductivity of nanoporous Bi thin films has been experimentally determined. Samples are fabricated by a liquid phase deposition, and their thermal conductivities are measured by a differential 3ω method. Nanoporous Bi thin films exhibit an order-of-magnitude reduction in thermal conductivity compared to t…
<div class="htmlview paragraph">Published investigations on the calculation of pressure drop of diesel particulate filters consider the contribution of substrate, soot, channel flow and inertial effects at the inlet and outlet of the channels. The model presented in this work considers further contributions as t…
Abstract A novel way of preparing an intumescent flame retardant (IFR) and its master batch by the reactive extrusion of melamine phosphate and pentaerythritol, together with a polypropylene (PP) carrier, in a twin‐screw extruder has been established. The effect of the PP carrier resin on the flame retardancy and wate…
<div class="htmlview paragraph">In the past decade, SCR deNOx technology with urea injection has grown to maturity. European OEMs will apply SCR deNOx to meet future heavy-duty emissions legislation starting with EURO-4 (2005/2006). Numerous research programs in Europe and the US have shown a variety of system l…
<div class="htmlview paragraph">The 2007 emission standards for both light-duty and heavy-duty diesel vehicles remain a challenge. A level of about 90% NOx conversion is required to meet the standards. Technologies that have the most potential to achieve very high NOx conversion at low temperatures of diesel exh…
Biotechnological studies towards the biosynthesis of polyhydroxyalkanoates (PHAs) biopolyesters have extensively progressed through the development of various metabolic engineering strategies. Historically, efficient PHA production has been achieved using the fermentation technology of naturally occurring PHA-producin…
The level splittings induced by a horizontal magnetic field in a parabolic two-dimensional quantum dot with spin-orbit interaction are obtained. Characteristic features induced by the spin-orbit coupling are the appearance of zero-field gaps as well as energy splittings that depend on the electronic state and the orie…
The pressure response of the scheelite phase of CaWO4 (YLiF4) and the occurrence of the pressure induced scheelite-to-wolframite (M-fergusonite) transition are reviewed and discussed. It is shown that the change of the axial parameters under compression is related with the different pressure dependence of the W-O (Li-…
The relaxors $\mathrm{Pb}({\mathrm{Zn}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}$ (PZN) and $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}$ (PMN) have very similar properties based on the dielectric response around the critical temperature ${T}_{c}$ (defined by the structural transition under th…
We revisit the expression for the conductance of a general nanostructure -- such as a quantum point contact -- as obtained from the linear response theory. We show that the conductance represents the strength of the Drude singularity in the conductivity $σ(k,k';iω\to 0)$. Using the equation of continuity for electric…
In order to provide a quantitatively accurate description of the band-gap variation with sizes in various II-VI semiconductor nanocrystals, we make use of the recently reported tight-binding parametrization of the corresponding bulk systems. Using the same tight-binding scheme and parameters, we calculate the electron…
This letter addresses the issue of surface softening versus stiffening during elastic deformation. Using a combination of molecular statics and ab initio calculations, we show that a solid surface can be either softer or stiffer elastically than the corresponding bulk. Whether a particular surface is softer or stiffer…
In this paper we have calculated electron transport coefficient in ballistic regime through a periodic dot sandwiched between uniform leads. We have calculated the Green's function (GF), density of states (Dos) and the coherent transmission coefficient (conductance) fully analytically. The quasi gap, bound states ener…
Mn-doped wurtzite GaN epilayers have been grown by nitrogen plasma-assisted molecular beam epitaxy. Correlated SIMS, structural and magnetic measurements show that the incorporation of Mn strongly depends on the conditions of the growth. Hysteresis loops which persist at high temperature do not appear to be correlated…
Novel poly(p-phenylenevinylene)s (PPVs) with a dendritic phenylazomethine (DPA) as a metal-collecting site were synthesized via the Heck reaction by filling the coordination site of DPA moiety via complexation with rare earth metal ions.
We present results of first-principles calculations of structural, magnetic, and electronic properties of small Fe clusters. It is shown that, while the lowest-energy isomers of Fe 3 and Fe 4 obtained in the framework of density functional theory within the generalized gradient approximation (GGA) are characterized by…
The structure of the polymeric substrate plays an important role in the nucleation of calcium carbonate crystals. In this study a synthetic water-soluble poly(acrylamide-co-2-acrylamido-2-methyl-1-propane sodium sufonate-co-n-vinyl pyrrolidone) was found to be a substrate favoring the nucleation of polymorphs of calci…