Materials Literature
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Recombinant sericin proteins of different molecular masses (17.4, 31.9, and 46.5 kDa), based on the 38-amino acid repetitive motif of native sericin, were cloned, expressed, and purified. The recombinant sericin self-assembled during dialysis (starting concentration of 2.5 mg/ml) forming twisted fibers. Circular dichr…
Abstract Three grades of bisphenol‐A polycarbonate—high molecular weight linear, high molecular weight branched and low molecular weight linear—and their blends have been studied by GPC, DMTA, DSC, rheometry and impact measurements. The molecular weight distribution of the blends agred with that predicted from the com…
The kinetic energy distribution of oxygen atoms resulting from electron impact dissociation of O 2 has been measured. A high‐resolution vacuum ultraviolet spectrometer was employed for the measurement of the OI(115.2 nm, 130.4 nm, 135.6 nm) fine‐structure emission line profiles at 35 eV and 100 eV electron impact ener…
This study presents a simulation model for the microcellular injection molding process in which supercritical fluid such as carbon dioxide or nitrogen is mixed with molten polymer and injected into the mold. Our model simulates the development of cells in the melt during injection molding. The effects of cell growth o…
The oxidation behavior and effect of oxidation on room‐temperature flexural strength were investigated for hot‐pressed Si 3 N 4 ceramics, with 3.33 and 12.51 wt% Lu 2 O 3 additives, exposed to air at 1400° and 1500°C for up to 200 h. Parabolic oxidation behavior was observed for both compositions. The oxidation produc…
Optical characteristics ( R, T, A ) of thin aluminum films with thicknesses from 1.7 to 15 nm were studied at a wavelength of 8 mm with allowance for a substrate material. The absorption exhibits a maximum for a film thickness of 2.5 nm. The experimental data are interpreted taking into account the dependence of elect…
A study of samples collected in the Don Carlos Stream, a small stream that runs across an urbanised and industrialised area of the Pampean plain, displayed abnormalities in the valves of Pinnularia gibba Ehrenberg. Three stations were sampled in different sectors of the stream: station A was located upstream and expos…
Abstract This paper presents an experimental study of the coordination number of ternary mixtures of particles of sizes 24.4 : 11.6 : 6.4 (mm) by the use of the liquid bridge technique. It generates detailed information about the distributed coordination numbers corresponding to different types of contacts between sma…
Silicon based polymers obtained by ammonolysis of organochlorosilylboranes and their pyrolytic transformation into Si-B-C-N ceramics were studied by a detailed solid-state NMR investigation. Sol–gel polymerisation/pyrolysis routes were applied to form Si-B-C-N materials with exceptional high-temperature stability. The…
To understand the behavior of octahedral hydroxyl-stretching modes (ν OH ) as a function of increasing tetrahedral layer charge, infrared and Raman spectroscopic studies were carried out on a series of synthetic saponites. The nature of the monovalent interlayer cation (Na or K) and the hydration of the samples were s…
Abstract A series of meso ‐thienyl‐substituted porphyrins with different porphyrin cores such as N 3 S, N 2 S 2 and N 3 O were synthesized and characterized. The thienyl groups at the meso ‐carbon atoms change the electronic properties of the porphyrin ring. The X‐ray structure solved for the N 2 S 2 porphyrin with fo…
We present a process for fabricating phase zone plates and other diffractive-optical elements that is capable of achieving high resolution, requires only a single lithography step, and no etching. For this process we use the negative resist hydrogen silsesquioxane (HSQ) (Dow Corning), which is sensitive to both electr…
The binding of the protonated fourth generation poly(amido amine) dendrimer as a guest polyelectrolyte (GPE) to the anionic homopolyelectrolyte poly( l -glutamic acid) sodium salt as a host polyelectrolyte (HPE) has been investigated by potentiometric and turbidimetric titration in aqueous 0.25 M NaCl solutions. The p…
The mode of occurrence and chemical composition of five types of micas with Rb- or Cs-dominant populations of interlayer cations, collected from the Red Cross Lake rare-element pegmatites in north-central Manitoba, are described here. All five micas are candidates for new mineral species but crystal-structural data an…
Three series of chiral liquid crystalline dimers were investigated, having a cholesteryl and a cyanobiphenylyl, butoxybiphenylyl or hexyloxybiphenylyl group connected to a variable alkyl spacer through ether linkages. Their properties were compared with those of the corresponding ester derivatives. The phase behaviour…
Abstract The specific intermolecular hydrogen‐bonding interaction between the ester carbonyl groups of poly( ε ‐caprolactone) (PCL) and the phenolic hydroxyl groups of catechin has been studied by Fourier‐transform infrared spectroscopy (FT‐IR) and differential scanning calorimetry (DSC). According to quantitative cur…
Molar absorptivity of the infrared (IR) fundamental OH-stretching vibration band at 3550 cm -1 was determined for rhyolitic glasses. Five obsidian samples, unheated and heated at 500-700 °C using an internally heated pressure vessel, were used to evaluate the dependence of the molar absorptivity and final quenched H 2…
Composites of polypropylene filled with untreated and treated calcium carbonate (CaCO3) have been prepared. The surface modification of calcium carbonate was done by using titanate coupling agent. The effect of this treatment on the interfacial adhesion and the dispersion of filler particles in the polymeric matrix wa…
Bulk and low molecular weight (LMW) (<1 kDa) water-extractable carbon were collected from fresh and microbially degraded wheat straw (Triticum aestivum L.) and crimson clover (Trifolium incarnatum L.) residues to monitor early-stage humification over an 8-wk incubation. Copper complexation parameters were determined f…
Abstract The phenomenon of storage hardening in solid natural rubber (NR) is presumed to occur by means of reactions between some non-rubber components and abnormal groups in rubber molecule. The main non-rubber constituents in NR are composed of proteins and lipids. The storage hardening behavior of NR purified by en…