Materials Literature
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The structure of beta-ketoacyl-[acyl carrier protein] reductase (FabG) from Escherichia coli was determined via the multiwavelength anomalous diffraction technique using a selenomethionine-labeled crystal containing 88 selenium sites in the asymmetric unit. The comparison of the E. coli FabG structure with the homolog…
Acute grazer toxicity of freshwater diatom biofilms was determined using Thamnocephalus platyurus Packard, an anostracan grazer, as the bioassay organism. The diatoms exhibited toxicity when the cells of the biofilm were freeze–thawed before the assay. The toxicity could be extracted from the biofilms with methanol an…
PURPOSE: To quantitate and characterize the expression of an engineered human transferrin receptor (ETR) as a marker gene by using magnetic resonance (MR) imaging. MATERIALS AND METHODS: Rat gliosarcoma 9L cells stably expressing ETR (ETR+) were used, with nontransfected (ETR-) cells serving as controls. A conjugate o…
The layer charge is perhaps the single most significant characteristic of 2: 1 layer phyllosilicates. Layer charge affects cation-retention capacity and adsorption of water, and various polar organic molecules. The effects of layer charge on the sorptive properties of organo- clays were illustrated by Lee et al. (1990…
Bonding characteristics of low-dielectric-constant (low-k) fluorine-incorporated silicon oxide (SiOF) and carbon-incorporated silicon oxide (SiOC) films prepared by plasma enhanced chemical vapor deposition were investigated by Fourier transform infrared spectroscopy (FTIR). The frequency of Si–O stretching vibration…
In this work, it is attempted to theoretically understand the phenomenon of wall slip through empirical and molecular models. Initially, we use the framework a transient network theory. We show that the severe disentanglement in the interfacial region can give rise to non-monotonic flow curve locally in that region. F…
This research aimed at defining a route for recovering precious metals from a very heterogeneous gold bearing sulphide and arsenide concentrate that was partially roasted and dumped by the 1960s when Santo António mine closed. Gold occurs in this concentrate as free particles in the range of 10-100 mum, most of them s…
The influence of the application of residues from the cellulose and paper industry in construction mortar was investigated. Mortars were prepared with CPI-S-32 or CPII-Z-32 Portland cements and sand in a 1:3 proportion. Four solids residues, i.e., Fiber, Dregs, Bottom Ash and Grit, were incorporated in the mortars in…
The aim of this work was to compare the in vitro wear and roughness of different composite resins after toothbrushing. Six resins were tested: Revolution (Kerr), Natural Flow (DFL), Flow It! (Jeneric-Pentron), Fill Magic Flow (Vigodent) - flowable composites, Silux Plus (3M) - microfilled composite, and Z100 (3M) - hy…
Dynamic rheological parameters such as storage modulus, G’, loss modulus, G”, and dynamic viscosity, h’, at 200°C were studied for Kevlar fibres, glass fibres and their hybrids reinforced linear low density polyethylene (LLDPE). Parallel plate rheometer was employed for these tests. G’, G” and h’ increased with the in…
To overcome difficulties (slip, sample disturbance) associated with traditional sensors, a semi-empirical method was developed to allow the use of a 4-bladed vane sensor in small strain oscillatory testing. It was assumed that the vane sensor acted as a bob with an acting radius, RV, different from the actual radius o…
The Microsoft Excel ‘Solver’ tool is a very simple but powerful procedure, even in the hands of the mathematically disadvantaged. It has very good application for quickly fitting experimental flow-curve data to non-Newtonian flow models with any number of parameters, and can cope with data from a number of sources. Ex…
Current technological advances require that the raw materials used in the production of electric devices and structural materials present special characteristics of chemical purity, size distribution and morphology of the particles. Tin oxides are mainly used as gas sensor and as surges suppressor (varistor). To achie…
This work proposes a procedure to estimate the dynamic damped behavior of fiber reinforced composite beams in flexural vibrations. A set of experimental dynamic tests were carried out in order to investigate the natural frequencies and modal shapes. These results are used to evaluate the damping factors by the program…
One of the most important compounds that are used in structural ceramics is alumina. During the last years, a variety of synthesis methods have been developed to obtain raw materials with suitable characteristics in terms of particle composition, size and shape. Controlled precipitation method (CP) allows to reach the…
A new Peltier system is introduced which offers new dimensions in temperature precision for parallel-plate and cone-and-plate measuring geometries in the temperature range from −30°C to +130°C. The use of an additional actively Peltier controlled hood (pat. pent.) reduces the temperature gradient across the sample to…
Silicon carbide has been extensively used in structural applications, especially at high temperatures. In this work, Y2O3, Al2O3 and SiO2 were added to beta-SiC in order to obtain highly dense ceramics. Sintering was conducted in a dilatometer and in a graphite resistance furnace and the densification behaviour was st…