Orbital evolution studies of two HMXB pulsars

High mass X-ray binary (HMXB) pulsars are of two types, persistent and transient. 4U1538-52 is a persistent HMXB whose orbit was previously measured to be circular but the RXTE observations revealed an eccentric orbit. We observed this system with RXTE-PCA in August 2003 and our timing analysis supports the eccentric orbit of the system. However, we do not find any evidence for orbital evolution. Rotational and tidal interactions between the stars of a closed binary system result in apsidal motion which can be measured in systems with eccentric orbit. 4U0115+63 is a Be-transient HMXB whose eccentric orbit was well-determined during its 1978 outburst. We report preliminary results from analysis of data obtained during the 1999 outburst of this source with the RXTE-PCA.

Studies on design, fabrication and reliability assessment of embedded passives on a high-density interconnect (HDI) organic substrate using a sequential build-up process

One of the foremost design considerations in microelectronics miniaturization is the use of embedded passives which provide practical solution. In a typical circuit, over 80 percent of the electronic components are passives such as resistors, inductors, and capacitors that could take up to almost 50 percent of the entire printed circuit board area. By integrating passive components within the substrate instead of being on the surface, embedded passives reduce the system real estate, eliminate the need for discrete and assembly, enhance electrical performance and reliability, and potentially reduce the overall cost. Moreover, it is lead free. Even with these advantages, embedded passive technology is at a relatively immature stage and more characterization and optimization are needed for practical applications leading to its commercialization.This paper presents an entire process from design and fabrication to electrical characterization and reliability test of embedded passives on multilayered microvia organic substrate. Two test vehicles focusing on resistors and capacitors have been designed and fabricated. Embedded capacitors in this study are made with polymer/ceramic nanocomposite (BaTiO3) material to take advantage of low processing temperature of polymers and relatively high dielectric constant of ceramics and the values of these capacitors range from 50 pF to 1.5 nF with capacitance per area of approximately 1.5 nF/cm(2). Limited high frequency measurement of these capacitors was performed. Furthermore, reliability assessments of thermal shock and temperature humidity tests based on JEDEC standards were carried out. Resistors used in this work have been of three types: 1) carbon ink based polymer thick film (PTF), 2) resistor foils with known sheet resistivities which are laminated to printed wiring board (PWB) during a sequential build-up (SBU) process and 3) thin-film resistor plating by electroless method. Realization of embedded resistors on conventional board-level high-loss epoxy (similar to 0.015 at 1 GHz) and proposed low-loss BCB dielectric (similar to 0.0008 at > 40 GHz) has been explored in this study. Ni-P and Ni-W-P alloys were plated using conventional electroless plating, and NiCr and NiCrAlSi foils were used for the foil transfer process. For the first time, Benzocyclobutene (BCB) has been proposed as a board level dielectric for advanced System-on-Package (SOP) module primarily due to its attractive low-loss (for RF application) and thin film (for high density wiring) properties.Although embedded passives are more reliable by eliminating solder joint interconnects, they also introduce other concerns such as cracks, delamination and component instability. More layers may be needed to accommodate the embedded passives, and various materials within the substrate may cause significant thermo -mechanical stress due to coefficient of thermal expansion (CTE) mismatch. In this work, numerical models of embedded capacitors have been developed to qualitatively examine the effects of process conditions and electrical performance due to thermo-mechanical deformations.Also, a prototype working product with the board level design including features of embedded resistors and capacitors are underway. Preliminary results of these are presented.

Breakdown in p‐n junction diodes made on polycrystalline silicon of large grain size

This communication describes the voltage‐current characteristics in the breakdown region of p‐n junctions made on polycrystalline silicon of large grain size. The observed soft breakdown characteristics have been explained by taking into account the effect of curvature of the junction near the grain boundaries.

NQR study of complexes between p-dichlorobenzene and some aromatic π acceptors

The charge-transfer complexes of p-dichlorobenzene (PDB) with some aromatic π acceptors such as m-nitrobenzaldehyde (MNB), picric acid (PA), p-nitrobenzoic acid (PNB), and m-dinitrobenzene (MDNB) were prepared by slowly adding the acceptor to the molten donor and then cooling the mass to 15°C. The NQR frequencies of these complexes were measured at room temperature. Contrary to the theoretical prediction, the NQR shift is positive, indicating that the NQR shift in donor-acceptor complexes is indirectly related to the charge-transfer interaction. Bond properties are discussed in terms of frequency shift.

High-Resolution Magic Angle Spinning Nmr-Studies Of P-31 And B-11 In Fast Ion Conducting Agi-Ag2o-P2o5 And Agi-Ag2o-B2o3 Glasses

Silver iodide-based fast ion conducting glasses containing silver phosphate and silver borate have been studied. An attempt is made to identify the interaction between anions by studying the chemical shifts of31P and11B atoms in high resolution (HR) magic angle spinning (MAS) NMR spectra. Variation in the chemical shifts of31P or11B has been observed which is attributed to the change in the partial charge on the31P or11B. This is indicative of the change in the electronegativity of the anion matrix as a whole. This in turn is interpreted as due to significant interaction among anions. The significance of such interaction to the concept of structural unpinning of silver ions in fast ion conducting glasses is discussed.

KO2: Realization of Orbital Ordering in a p-Orbital System

KO2 is a molecular solid consisting of oxygen dimers. K present in the lattice donates an electron which goes on to occupy the O p levels.As the basic electronic structure is similar to that of an oxygen molecule, except for broadening due to solid state effects, KO2 represents the realization of the doping of oxygen molecules arranged in a lattice. These considerations alone result in magnetism with high ordering temperatures as our calculations reveal. However, we find that the high temperature structure is unstable to an orbital ordering (OO) transition. The microscopic considerations driving the OO transition, however, are electrostatic interactions instead of the often encountered superexchange driven ordering within the Kugel-Khomskii model often used to describe the OO. This OO transition is also found to preclude any possibility of high magnetic ordering temperatures, which otherwise seemed possible.

On the unreasonable effectiveness of Gutzmer's formula

In this article we plan to demonstrate the usefulness of `Gutzmer's formula' in the study of various problems related to the Segal-Bargmann transform. Gutzmer's formula is known in several contexts: compact Lie groups, symmetric spaces of compact and noncompact type, Heisenberg groups and Hermite expansions. We apply Gutzmer's formula to study holomorphic Sobolev spaces, local Peter-Weyl theorems, Paley-Wiener theorems and Poisson semigroups.

Regulation of cytochrome P-450b/e gene expression by a heme- and phenobarbitone-modulated transcription factor

The cloned DNA fragment of the cytochrome P-450b/e gene containing the upstream region from position -179 through part of the first exon is faithfully transcribed in freeze-thawed rat liver nuclei. Phenobarbitone treatment of the animal strikingly increases this transcription, and the increase is blocked by cycloheximide (protein synthesis inhibitor) or CoCl2 (heme biosynthetic inhibitor) treatment of animals. This picture correlates very well with the reported cytochrome P-450b/e mRNA levels in vivo and run-on transcription rates in vitro under these conditions. The upstream region (from position -179) was assessed for protein binding with nuclear extracts by nitrocellulose filter binding, gel retardation, DNase I treatment ("footprinting"), and Western blot analysis. Phenobarbitone treatment dramatically increases protein binding to the upstream region, an increase once again blocked by cycloheximide or CoCl2 treatments. Addition of heme in vitro to heme-deficient nuclei and nuclear extracts restores the induced levels of transcription and protein binding to the upstream fragment, respectively. Thus, drug-mediated synthesis and heme-modulated binding of a transcription factor(s) appear involved in the transcriptional activation of the cytochrome P-450b/e genes, and an 85-kDa protein may be a major factor in this regard.

An unusual C-H center dot center dot center dot O hydrogen bond mediated reversal of polypeptide chain direction in a synthetic peptide helix

An unusual C-terminal conformation has been detected in a synthetic decapeptide designed to analyze the stereochemistry of helix termination in polypeptides. The crystal structure of the decapeptide Boc-Leu-Aib-Val-Ala-Leu-Aib-Val-(D)Ala-(D)Leu-Aib-OMe reveals a helical segment spanning residues 1-7 and helix termination by formation of a Schellman motif, generated by (D)Ala(8) adopting the left-handed helical (alpha(L)) conformation. The extended conformation at (D)Leu(9) results in a compact folded structure, stabilized by a potentially strong C-H ... O hydrogen bond between Ala(4) (CH)-H-alpha and (D)Leu(9)CO. The parameters for C-H ... O interaction are Ala(4) (CH)-H-alpha .. O=C (D)Leu(9) distance 3.27 Angstrom C-alpha-H .. O angle 176 degrees, and O .. H-alpha distance 2.29 Angstrom. This structure suggests that insertion of contiguous D-residues may provide a handle for the generation of designed structures containing more than one helical segment folded in a compact manner. (C) 2000 Academic Press.

Ultrasonic measurement of the elastic constants of sodium p-nitrophenolate dihydrate single crystals

Sodium p-nitrophenolate dihydrate single crystals possess excellent nonlinear optical properties such that they can be used for optical second-harmonic generation. It belongs to the orthorhombic system with the space group Ima2. Slow evaporation or slow cooling techniques can be used to grow good optical quality single crystals from supersaturated solution. All the nine elastic constants of this crystal have been measured using an ultrasonic technique. Samples for measurements have been cut along desired crystallographic axes and the pulse echo overlap technique has been used to measure longitudinal and shear ultrasonic wave velocities along appropriate symmetry directions in the crystal. The McSkimin Delta t criterion has been applied to determine the round trip travel time accurately, from which the nine elastic constants have been evaluated. Temperature variation of selected elastic constants in a limited range have also been measured and reported.

pH mediated delamination of anionic clay-like nickel-zinc hydroxysalt in water through intercalation of zwitterionic p-aminobenzoate ions

p-aminobenzoate could be intercalated into the anionic clay, Ni3Zn2(OH)(8)(OAc)(2)center dot 2H(2)O at a high pH (similar to 10). When the pH was reduced to similar to 7 while washing colloidal dispersion due to delamination was observed. The development of partial positive charge on the amine end of the intercalated anion causes repulsion between the layers leading to delamination and colloidal dispersion of monolayers in water. The layers could be restacked from the colloid to form the parent solid either by increasing the pH or by evaporation.

Biotransformations of α-terpineol in the rat: Its effects on the liver microsomal cytochrome P-450 system

Alpha-Terpineol (I), a monocyclic monoterpene tertiary alcohol, is widely used in the manufacture of perfumes, cosmetics, soaps and antiseptic agents. It was reported earlier (Horning et al. 1976) that this monoterpene alcohol when administered to humans is hydroxylated to p-menth-l,2,8-triol (II). It is not known whether c~-terpineol also produces other metabolites during its metabolism in the mammalian system and if so, the nature of these metabolites.

Characterization of compact ICP ion source for focused ion beam applications

A compact, high brightness 13.56 MHz inductively coupled plasma ion source without any axial or radial multicusp magnetic fields is designed for the production of a focused ion beam. Argon ion current of density more than 30 mA/cm(2) at 4 kV potential is extracted from this ion source and is characterized by measuring the ion energy spread and brightness. Ion energy spread is measured by a variable-focusing retarding field energy analyzer that minimizes the errors due t divergence of ion beam inside the analyzer. Brightness of the ion beam is determined from the emittance measured by a fully automated and locally developed electrostatic sweep scanner. By optimizing various ion source parameters such as RF power, gas pressure and Faraday shield, ion beams with energy spread of less than 5 eV and brightness of 7100 Am(-2)sr(-1)eV(-1) have been produced. Here, we briefly report the details of the ion source, measurement and optimization of energy spread and brightness of the ion beam. (C) 2010 Elsevier B.V. All rights reserved.

Elasto-plastic Cracking Analysis of Reinforced Concrete

A new elasto-plastic cracking constitutive model for reinforced concrete is presented. The nonlinear effects considered cover almost all the nonlinearities exhibited by reinforced concrete under short term monotonic loading. They include concrete cracking in tension, plasticity in compression, aggregate interlock, tension softening, elasto-plastic behavior of steel, bond-slip between concrete, and steel reinforcement and tension stiffening. A new procedure for incorporating bondslip in smeared steel elements is described. A modified Huber-Hencky-Mises failure criterion for plastic deformation of concrete, which fits the experimental results under biaxial stresses better, is proposed. Multiple cracking at Gauss points and their opening and closing are considered. Matrix expressions are developed and are incorporated in a nonlinear finite element program. After the objectivity of the model is demonstrated, the model is used to analyze two different types of problems: one, a set of four shear panels, and the other, a reinforced concrete beam without shear reinforcement. The results of the analysis agree favorably with the experimental results.