Low-temperature gate dielectrics formed by plasma anodisation ofsilicon nitride

Silicon nitrides, deposited on silicon by PECVD using an SiH₄ /NH₃ plasma at 300°C, were anodised in an oxygen plasma at 500°C. The resulting dielectric appears to have lower fixed charge, leakage current and interface trap density than the original PECVD nitride, and to have the potential of use as a gate dielectric for MIS devices in VLSI circuits     

Cyclic AMP protects against staurosporine and wortmannin-induced apoptosis and opioid-enhanced apoptosis in both embryonic and immortalized (F-11kappa7) neurons

The mechanism by which opiates affect fetal development is unknown, but one potential target is the programmed cell death (apoptosis) pathway of neurons. Apoptosis was induced in both primary neuronal cultures from embryonic day 7 cerebral hemispheres of chick brain (E7CH) and the F-11kappa7 cell line (an immortalized mouse neuroblastoma x dorsal root ganglion hybrid stably transfected to overexpress kappa-opioid receptors) by either staurosporine or the phosphatidylinositol 3-kinase inhibitors wortmannin and LY294002. Cells pretreated with either the mu-specific opioid agonist morphiceptin (E7CH) or the kappa-specific opioid agonist U69,593 (F-11kappa7) for 24 h showed increased apoptosis in response to staurosporine or wortmannin when compared with non-pretreated cells. The effects of morphiceptin and U69,593 were time- and dose-dependent and antagonist-reversible, suggesting that they were receptor-mediated. Neither morphiceptin nor U69,593 by themselves had any measurable effect on cell viability or DNA fragmentation, and coaddition of opiates at the same time as staurosporine, wortmannin, or LY294002 did not enhance apoptosis. Time course studies indicated a maximal opioid effect at a time (16-24 h) when inhibition of adenylate cyclase had been maximal for many hours. Addition of dibutyryl cyclic AMP either before or at the time of opioid addition protected against apoptosis and reduced fragmentation to levels seen for staurosporine plus dibutyryl cyclic AMP alone. The specificity for cyclic AMP was confirmed by showing protection with the specific agonist Sp-adenosine 3',5'-cyclic monophosphothioate and increased killing with the antagonist Rp-adenosine 3',5'-cyclic monophosphothioate. We conclude that the opioid enhancement of apoptosis is based on the inhibition of adenylate cyclase and that the effect is time-dependent.     

Semi-orthogonal versus orthogonal wavelet basis sets for solvingintegral equations

The two categories of wavelets, orthogonal and semi-orthogonal, are compared and it is shown that the semi-orthogonal wavelet is best suited for integral equation applications. The Battle-Lemarie orthogonal wavelet and the spline generated semi-orthogonal wavelet are each used to solve for the current distribution on an infinite strip illuminated by a transverse magnetic (TM) plane wave and a straight thin wire illuminated by a normally incident plane wave. The grounds for comparison are accuracy in characterizing the current, matrix sparsity, computation time, and singularity extraction capability. The limitations and advantages of solving integral equations with each of the two wavelet categories are discussed     

A study of vacuum-deposited films of CrTe and CrSe on single crystals

Vacuu,-deposited films of CrTe and CrSe grown on (100), (110) and (111) faces of NaCl and also on cleavage faces of mica at different substrate temperatures have been studied by electron diffraction. These deposits, normally having a NiAs type structure, also developed new cubic phases for both the systems at high substrate temperatures. The normal and the new phases grew epitaxially on single-crystal substrates at appropriate temperatures, often accompanied by a {111} twinned structure of the cubic phase.     

Programmable memory cell using quantum confined Stark effect in multi-quantum well heterojunction bipolar transistor

A three terminal bistable programmable memory cell which can be read either optically or electrically is proposed and demonstrated. The device is based on using Stark effect of the excitonic transitions in a multi-quantum well base region of a heterojunction bipolar transistor. The single device can be flipped (and held) from low transmittance (high voltage) to high transmittance (low voltage) state and vice versa by a varying base current signal.<>     

Numerical simulation of ultrasonic transmission through curved interface

The direct boundary integral equation formalism is used to model reflected and transmitted wave fields due to a bounded ultrasonic beam incident upon an arbitrarily curved interface separating a fluid and a solid media. The numerical procedure involves application of point collocation with quadratic isoparametric approximation that reduce the integral equations to a discrete set of linear algebraic equations. Numerical results are provided for plane, concave and convex interfaces for incident beam profiles which are Gaussian or approximately rectangular. The case of surface wave excitation on a plane interface is considered and features of their numerical solution are discussed. Constraints on the various parameters of the numerical model and their effects on the accuracy of the solution are investigated in detail.     

2-Aminobenzothiazoles Inhibit Virulence Gene Expression and Block Polymyxin Resistance in Salmonella enterica

One promising strategy to combat antibiotic-resistant bacteria is to develop compounds that block bacterial defenses against antibacterial conditions produced by the innate immune system. Salmonella enterica, which causes food-borne gastroenteritis and typhoid fever, requires histidine kinases (HKs) to resist innate immune defenses such as cationic antimicrobial peptides (CAMPs). Herein, we report that 2-aminobenzothiazoles block histidine kinase-dependent phenotypes in Salmonella enterica serotype Typhimurium. We found that 2-aminobenzothiazoles inhibited growth under low Mg²⁺, a stressful condition that requires histidine kinase-mediated responses, and decreased expression of the virulence genes pagC and pagK. Furthermore, we discovered that 2-aminobenzothiazoles weaken Salmonella’s resistance to polymyxin B and polymyxin E, which are last-line antibiotics and models for host defense CAMPs. These findings raise the possibilities that 2-aminobenzothiazoles can block HK-mediated bacterial defenses and can be used in combination with polymyxins to treat infections caused by Salmonella.