Interfacial structure and reaction mechanism of AlN/Ti joints

Bonding of AlN to Ti was performed at high temperatures in vacuum. The bonding temperature ranged from 1323 to 1473 K, while the bonding time varied from 7.2 up to 72 ks. The reaction products were examined using elemental analysis and X-ray diffraction. TiN, Ti3AlN (τ1), and Ti3Al were observed at the AlN/Ti interface, having various thickness at different bonding conditions. The thickness of TiN and Ti3AlN layers grew slowly with bonding time. On the other hand, growth of the Ti3Al layer followed Fick’s law. The activation energy of its growth was found to be 146 kJ mol-1. When thinner Ti foil (20 μm) was joined to AlN at 1473 K for a long time (39.6 ks), the Ti central layer has completely consumed and another ternary compound Ti2AlN(τ2) started to form. A maximum bond strength was achieved for an AlN/Ti (20 μm) joint made at 1473 K for 28.8 ks, after which the bond strength of the joint deteriorated severely. This revised version was published online in November 2006 with corrections to the Cover Date.     

THERMOXIDATIVE AND HYDROLYTIC CHANGES IN OILS USED FOR FRYING OF FROZEN PREFRIED FOODS

Palm olein with 22.9 h of stability at 100 C (by the Rancimat method) and low acid and peroxide values of 0.184% and 1.33 meq/kg, respectively, was used to study the deteriorative effect of frying of frozen prefried potatoes and chicken and compared it with the effect of frying the same fresh foods. Quality characteristics of palm olein were monitored by following the changes in physical and chemical properties; foam height (FH), smoke point (SP), refractive index (RI), viscosity (Vis), acid value (AV), peroxide value (PV), polymer content (%Pol.), oxidized fatty acids (%OFA), thiobarbituric acid (TBA) value and, conjugated acids (absorbance at 232 nm for conjugated dienes and at 268 nm for conjugated trienes) with the progress in frying time of up to 20 h. Results revealed that frying the frozen prefried foods express more deteriorative effect than the fresh foods throughout the frying process.     

Quality of Five Rice Varieties Grown in Egypt

The quality of two new drought-resistant varieties of rice (IR441 and IR3304) grown in Egypt, were compared with three commercial varieties (Selection 180, Reiho and Giza 172). Based on milling yield, IR441 and IR3304 showed lowest rice quality. Gelatinization temperature was highest in IR441 and lowest in IR3304 and Giza 172. During cooking, water uptake ratio and elongation ratio were higher in IR441 and Selection 180. Protein content was in the range 4–6% for all varieties. Amino acid analysis indicated nutritional superiority of Selection 180 over the other varieties. With the exception of lysine and threonine, the amount of each of the other essential acids in IR441 and Reiho matched or exceeded the FAO/ WHO pattern. IR3304 is deficient in the most number of essential acids (lysine, threonine, and isoleucine).     

ELECTROMAGNETIC TRANSIENTS ON COMPENSATED LINES UNDER CORONA

ABSTRACT

The purpose of this paper is to present a digital computational method for the determination of the fast electromagnetic transients propagating on compensated overhead power lines, evoked by internal or external over voltages, as effected by corona discharges. The approach enables the consideration of series capacitor and shunt reactor compensation. The line model is based on time-domain solution using the Runge-Kutta-Verner numerical technique to solve a set of simultaneous differential equations, whose number depends on the assumed number of line sections, as derived from the line equivalent circuit. The increase of the location-dependent conductor effective radius due to corona is considered as one of variable sets, using an iterative solution procedure. To avoid the parasitic Gibbs-oscillations due to the finite number of line sections (which are superimposed on the actual solutions, a set of properly chosen damping resistors is added to the line model, yielding a frequency-dependent damping. The simulation of the corona discharge uses a model derived from an experimentally measurable voltage-charge hysteresis loop relationship of a line test length. As far the input voltage stimuli are concerned, so the model can consider any voltage-time function (step, ramp, double-exponential, sine waves...etc), or even be in the form of tabulated numerical data. The validity of the model is checked by comparing its results to corresponding measurements.     

Micro-fabrication of ceramics:Additive manufacturing and conventional technologies

Ceramic materials are increasingly used in micro-electro-mechanical systems(MEMS)as they offer many advantages such as high-temperature resistance,high wear resistance,low density,and favourable mechanical and chemical properties at elevated temperature.However,with the emerging of additive manufacturing,the use of ceramics for functional and structural MEMS raises new opportunities and challenges.This paper provides an extensive review of the manufacturing processes used for ceramic-based MEMS,including additive and conventional manufacturing technologies.The review covers the micro-fabrication techniques of ceramics with the focus on their operating principles,main features,and processed materials.Challenges that need to be addressed in applying additive technologies in MEMS include ceramic printing on wafers,post-processing at the micro-level,resolution,and quality control.The paper also sheds light on the new possibilities of ceramic additive micro-fabrication and their potential applications,which indicates a promising future.     

DETECTION OF FIMBRIAE (CFA/I) ON ENTEROTOXIGENIC ESCHERICHIA COLI USING ANTIBODIES

Fimbriae (CFA/I) were isolated after detachment from an enterotoxigenic Escherichia coli ( ETEC) strain H10407, purified by successive isoelectric point precipitation at pH 3.5, and injected into rabbits. The antisera containing the polyclonal antibodies against the fimbrial proteins (antigens) were then used to detect the presence of CFA/I on other E. coli cultures using an indirect ELISA system. The ELISA procedures for the CFA/I assay was as sensitive as the DNA hybridization for detecting the ETEC strains. Two bands (major and minor) were present when the isolated fimbrial proteins were subjected to SDS-PAGE. The major band had a molecular mass of 40.3 and the minor 36.4 kDa. Electron microscopy of the fimbriae appeared as thin thread rods with variable length (5–15 μm ).     

OPTIMAL COMPENSATION OF NONUNIFORMLY LOADED RADIAL FEEDERS,WITH APPLICATIONS

ABSTRACT

This paper presents a generalized mathematical model for assessing the loss reduction in nonunlformly loaded radial feeders by capacitor shunt compensation. The model allows for the simultaneous presence of linearly increasing feeder load density in addition to a concentrated load at the feeder end. Any number of compensating capacitors can be included in the analysis. The model is then applied to study the effect of the number of feeders on the achieveable optimal reduction in the feeder copper loss. The paper also gives the optimal size and locations of these capacitors, for any number of radial feeders eraenatlng from a distribution substation to serve a certain total load.