A triple channel HEMT on InP (Camel HEMT) for large-signalhigh-speed applications

A triple channel HEMT structure grown on InP has been developed (the “Camel” HEMT). Starting from a dual channel (InGaAs/InP) HEMT that utilizes both the high electron mobility of InGaAs and the low impact ionization coefficient of InP, a third InGaAs channel as well as a quaternary carrier supply layer have been introduced to improve the electron transfer and thus the transistor performance. The design of the new transistor structure and its fabrication technology are described. Static and dynamic performances for an 0.8 μm gate length Camel HEMT are presented and compared to standard double channel HEMT transistors that are fabricated with the same geometry and process conditions. The results show that this new structure offers a very good tradeoff between high breakdown voltage and current gain cutoff frequency     

Characterization of a branched-chain amino-acid aminotransferase from Schizosaccharomyces pombe

The Saccharomyces cerevisiae genes for the cytosolic and mitochondrial branched-chain amino-acid aminotransferases (BCAT) were isolated recently. These genes show significant homology to mammalian ECA39, originally isolated as a gene regulated by the c-myc oncogene. We now report the isolation of the Schizosaccharomyces pombe eca39/BCAT gene. The S. pombe protein shows 47–52% identity to other eukaryotic BCAT proteins isolated from S. cerevisiae, nematode, mouse and man. A genetic growth assay for BCAT activity was established using an S. cerevisiae strain disrupted in both BCAT isoenzymes. Consequently, the activity of the S. pombe BCAT was demonstrated by genetic and biochemical means. Possible applications of BCAT-encoding genes as selection markers in yeast transformation are proposed. The sequence has been deposited in the GenBank data library under Accession Number U88029. © 1998 John Wiley & Sons, Ltd.     

Efficient Set Intersection with Simulation-Based Security

We consider the problem of computing the intersection of private datasets of two parties, where the datasets contain lists of elements taken from a large domain. This problem has many applications for online collaboration. In this work, we present protocols based on the use of homomorphic encryption and different hashing schemes for both the semi-honest and malicious environments. The protocol for the semi-honest environment is secure in the standard model, while the protocol for the malicious environment is secure in the random oracle model. Our protocols obtain linear communication and computation overhead. We further implement different variants of our semi-honest protocol. Our experiments show that the asymptotic overhead of the protocol is affected by different constants. (In particular, the degree of the polynomials evaluated by the protocol matters less than the number of polynomials that are evaluated.) As a result, the protocol variant with the best asymptotic overhead is not necessarily preferable for inputs of reasonable size.     

Microvoids in electrochemically hydrogenated titanium-based alloys

In a recent study, it was observed that electrochemical charging with hydrogen produces microvoids both in wrought and in additively manufactured, electron beam melted (EBM) Ti–6Al–4V alloys. This result is surprising since titanium forms stable hydrides and has an exothermic heat of hydrogen solution. By comparison, hydrogen bubble formation is typically observed only in metals and alloys with an endothermic heat of hydrogen solution that do not form hydrides. Here, we evaluate possible mechanisms for the formation of microvoids and bubbles in Ti-based alloys. Additional experimental work confirms that voids do not form in electrochemically hydrogenated, single-phase, pure wrought Ti, whereas they do form in the wrought Ti–6Al–4V alloy hydrogenated under the same conditions. In commercially pure Ti (CP–Ti), hydride is formed from the surface inward, and the surface is brittle and heavily cracked and disintegrated. By contrast, in the two-phase alloy, hydrides are formed also deeper in the bulk, and microvoids are evident both adjacent to the surface and along interphase boundaries. Alongside the forming hydride, the surface integrity is maintained, although some cracks are formed due to microvoid coalescence. While the incorporation of hydrogen into the alloy causes a large increase in its volume, we note that the precipitation of hydride from a supersaturated solution causes a net contraction. We suggest that the mechanism that best reflects the experimental evidence of microvoids formation is a manifestation of the contraction that results from hydride precipitation from a hydrogen-supersaturated alloy.     

Kinetic degradation of amoxicillin by using the electro-Fenton process in the presence of a graphite rods from used batteries

This study reports the removal of amoxicillin(AMX) in aqueous media using the electro-Fenton process in the presence of a graphite cathode recovered from used batteries.The impact of the relevant parameters on the electro-Fenton process,namely the applied current intensity,the temperature,the initial concentration of AMX and the initial concentration of ferrous ions were investigated.The results showed that the optimal values were:I=600 mA,T=25℃,[AMX]_0=0.082 mmol·L~(-1) and [Fe~(2+])=1 mmol·L~(-1),leading to 95% degradation and 74% mineralization.The model parameters of AMX mineralization were determined using nonlinear methods,showing that it follows a pseudo-second-order kinetic.The Energy consumption(EC) calculated under the optimal values was found to be 0.79 kW·h·g~(-1) which was of the same order of magnitude of those reported in other findings;while it is noteworthy that the electrodes used in our study are of a lower cost.     

Argan oil-in-water emulsions: Preparation and stabilization

We prepared stable oil-in-water emulsions of argan oil with two different types of mixtures of nonionic emulsifiers. Three different types of oil (Israeli argan oil, Moroccan argan oil, and soybean oil) were emulsified with mixtures of Span 80 and Tween 80. The optimum HLB value for argon oil was 11.0 (±1.0). The argan oil-in-water emulsions were stable for more than 5 mon at 25°C. Synergistic effects were found in enhancing stability of emulsions prepared with sucrose monostearate. The origin of the oil and the internal content of natural emulsifiers, such as monoglycerides and phospholipids, have a profound influence on its interfacial properties and on the stability of the argan oil-in-water emulsions.     

NMR relaxation studies to explore the role of emulsifier in tristearin polymorphic transformation

Proton magnetic resonance measurements were performed onα andβ polymorphs of tristearin crystals. T₁ relaxation time was measured with the Bruker PC Minispec at 20 MHz and 37° on the pure triglyceride crystals and therefore on tristearin crystallized in the presence of different solid surfactants. A significant negative correlation for T₁ values and different compositions ofα andβ polymorphs in a mechanical mixture was found. The shortening of T₁ relaxation time of theβ form was found to be different for the various types of the added surfactants while they have no effect on the relaxation time of theα form. A model was proposed according to which the presence of additives, such as surfactants, generates vacancies within the crystal lattice of triglyceride and enhances the freedom of rotation of the fat molecule about the terminal carbon-carbon bond.     

HPLC analysis of nonionic surfactants. Part IV. Polyoxyethylene fatty alcohols

A high performance liquid chromatographic technique (HPLC) was applied to analyze nonionic surfactants of ethylene oxide (EO) adducts. Pattern analyses of EO adducts (ethers), with 2, 10 and 20 average EO units, were carried out using a Lichrosorb SI-60 (10 μm) column (4.6 mm inner dimension (id)×25 cm) under the following conditions: mobile phase-mixture of isopropanol, methanol and n-hexane (gradient): temperature of 50 C: UV detector at 220 nm. No derivatization of the compounds was needed. An improved baseline, in spite of gradient elution, was achieved by adding negligible amounts of anthracene to the eluents. Brominated ethoxylated alcohols, resulting from the addition of bromine to the hydrophobic chain of the ethoxylated fatty alcohol, did not require any changes in the elution conditions.     

Extended naming conventions for communicating processes

We present two extensions of the naming conventions of Communicating Sequential Proceses [11]: computed communication targets and unspecified communication targets, as well as corresponding extensions to the system of cooperating proofs [3] for verifying distributed programs. These language extensions are important for the natural expressibility of many distributed programs. Examples of the use of these extensions are discussed and verified.     

Solvent-swelling of vulcanizates reinforced by fibrillar fillers

Two models are proposed for vulcanizates reinforced by fibrillar fillers. These are then analysed for swelling behaviour by considering the swelling of a cylinder of elastomer surrounding an individual fibre and firmly attached to it. A complex of such cylinders in a laminated geometry is then studied. Graphs are given which may be used to study the swelling of rubberized cord.