Electron-Phonon Anomaly Related to Charge Stripes: Static Stripe Phase Versus Optimally Doped Superconducting La1.85Sr0.15CuO4

Inelastic neutron scattering was used to study the Cu-O bond-stretching vibrations in optimally doped La_1.85Sr_0.15CuO₄ (T_c = 35 K) and in two other cuprates showing static stripe order at low temperatures, i.e., La_1.48Nd_0.4Sr_0.12CuO₄ and La_1.875Ba_0.125CuO₄. All three compounds exhibit a very similar phonon anomaly, which is not predicted by conventional band theory. It is argued that the phonon anomaly reflects a coupling to charge inhomogeneities in the form of stripes, which remain dynamic in superconducting La_1.85Sr_0.15CuO₄ down to the lowest temperatures. These results show that the phonon effect indicating stripe formation is not restricted to a narrow region of the phase diagram around the so-called 1/8 anomaly but occurs in optimally doped samples as well.     

A multi-objective discrete reliability optimization problem for dissimilar-unit standby systems

A new methodology for the reliability optimization of a k dissimilar-unit nonrepairable cold-standby redundant system is introduced in this paper. Each unit is composed of a number of independent components with generalized Erlang distributions of lifetimes arranged in a series–parallel configuration. We also propose an approximate technique to extend the model to the general types of nonconstant hazard functions. To evaluate the system reliability, we apply the shortest path technique in stochastic networks. The purchase cost of each component is assumed to be an increasing function of its expected lifetime. There are multiple component choices with different distribution parameters available for replacement with each component of the system. The objective of the reliability optimization problem is to select the best components, from the set of available components, to be placed in the standby system to minimize the initial purchase cost of the system, maximize the system mean time to failure, minimize the system variance of time to failure, and also maximize the system reliability at the mission time. The goal attainment method is used to solve a discrete time approximation of the original problem.      

Moment method analysis of mutual interaction in MRI phased array coils

We describe the use of a computational method for determining the overlap distance minimizing the mutual interaction between two adjacent coils that constitute a part of a phased array system used in MRI. The method is based upon the method of moments, and the analysis is carried out at a target imaging frequency to obtain the overlap distance. For a variety of complex RF phased array coils, we can determine, using the proposed approach, the overlap distance between nearest neighbor block element RF coils such that the mutual interaction is nullified or minimized. We give experimental results to validate the proposed approach. When compared with the experimental data, our theoretical prediction is in excellent agreement.     

MASP1 (MBL-associated serine protease 1)

The intracellular concentration of many steroids and xenobiotics is influenced by the membrane protein P-glycoprotein (Pgp). It has been inferred that the intracellular retention of many drugs that upregulate Pgp or modulate Pgp function might also be affected by Pgp. However, the ability of Pgp to influence the translocation of these drugs needs to be established to understand Pgp's influence upon their pharmacological effect. We utilized two approaches to determine the interaction of several agents with Pgp: (a) an in vitro system, LLC-PK1 cell lines and derivative LLC cell lines stably expressing on the apical membrane either mouse mdr1a or human MDR1 Pgp grown as polarized epithelium in transwell culture to measure translocation of radiolabeled drugs; and (b) an in vivo system, mdr1a nullizygous and wild-type animals, to compare the contribution of Pgp to in vivo distribution of radiolabeled drugs. In combination these complementary approaches identified erythromycin as a drug whose intracellular retention is influenced by Pgp, while the intracellular accumulation and tissue distribution of retinoic acid and benzo(a)pyrene were unaffected by Pgp.     

Improved method for determining bisphenol A in polycarbonate products without using dichloromethane

An improved method for determination of bisphenol A (BPA), phenol (PH), p-tert-butylphenol (PTBP) and diphenylcarbonate (DPC) in polycarbonate products was developed without using the hazardous solvent dichloromethane. Polycarbonate samples were ground to powder or cut into small pieces, and 0.5 g was soaked in 5 mL of acetonitrile for 24 hours at 40 degrees C. The test solution was then filtered and subjected to HPLC analysis. The proposed method was evaluated by comparison of the results with those of the standard method for 14 polycarbonate products. Extraction ratios (average values obtained by the present method/average values obtained by the standard method) of BPA, PH, PTBP and DPC were 0.89-1.19, 0.89-1.14, 0.94-1.30 and 1.08-1.11, respectively. While 120 mL/sample of organic solvent is required in the standard method, only 5 mL/sample of acetonitrile was used in our new method.     

On-line grid-packing with a single active grid

In this paper, we study the problem of packing rectangular items into a minimum number of square grids in an on-line manner with a single active grid, where the size of each grid is m×m for some positive integer m, and the height and the width of each item are positive integers smaller than or equal to m, respectively. We prove two elementary bounds on the asymptotic competitive ratio of an optimal on-line algorithm, that is at least 23/11 and at most . We then propose an on-line algorithm that achieves a competitive ratio O((loglogm)²).     

Dissimilatory arsenate reduction by a facultative anaerobe, Bacillus sp. strain SF-1

Bacillus sp. strain SF-1, isolated first as a selenate-reducing bacterium, was characterized as a novel arsenate-reducing bacterium. Strain SF-1 rapidly reduced 10 mM levels of arsenate to arsenite with concomitant cell growth and lactate oxidation under anoxic conditions, indicating that arsenate can act as the terminal electron acceptor for anaerobic respiration (dissimilatory arsenate reduction). Strain SF-1 can use various organic compounds including synthetic sewage mainly composed of peptone and meat extract as the electron donors for arsenate reduction. Although strain SF-1 can grow aerobically, which is very rare for dissimilatory arsenate-reducing bacteria, the presence of oxygen inhibited the arsenate reduction. On the other hand, the presence of nitrate or selenate, which can support the growth of strain SF-1 as electron acceptors, did not significantly inhibit the arsenate reduction. Arsenate-reducing activity, that is, arsenate reductase, was exhibited in strain SF-1 only when grown on arsenate, but the enzyme could not reduce other oxyanions including nitrate and selenate. It was presumed that arsenate reduction was carried out by an enzyme system separate from those of nitrate and selenate reduction, and the arsenate reductase was inducible and specific for arsenate. These results suggest that strain SF-1 may be utilized for extracting arsenic from contaminated soil for the purpose of bioremediation.     

Identification of ultradilute dopants in ceramics

The properties of ceramic materials are strongly influenced by the presence of ultradilute impurities (dopants). Near-edge X-ray absorption fine structure (NEXAFS) measurements using third-generation synchotron sources can be used to identify ultradilute dopants, provided that a good theoretical tool is available to interpret the spectra. Here, we use NEXAFS analysis and first-principles calculations to study the local environments of Ga dopants at levels of 10 p.p.m in otherwise high-purity MgO. This analysis suggests that the extra charge associated with substitutional Ga on a Mg site is compensated by the formation of a Mg vacancy. This defect model is then confirmed by positron lifetime measurements and plane-wave pseudopotential calculations. This powerful combination of techniques should provide a general method of identifying the defect states of ultradilute dopants in ceramics.     

Inter-laboratory validation studies of analytical method for determination of chloramphenicol in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSD(R)) were 10.5 and 6.8%, HORRAT(R) values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSD(R) were 9.8 and 12.3%, and HORRAT(R) values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance.     

A new evaluation method of electron optical performance of high beam current probe forming systems

A new numerical simulation method is presented for the electron optical property analysis of probe forming systems with point cathode guns such as cold field emitters and the Schottky emitters. It has long been recognized that the gun aberrations are important parameters to be considered since the intrinsically high brightness of the point cathode gun is reduced due to its spherical aberration. The simulation method can evaluate the 'threshold beam current I(th)' above which the apparent brightness starts to decrease from the intrinsic value. It is found that the threshold depends on the 'electron gun focal length' as well as on the spherical aberration of the gun. Formulas are presented to estimate the brightness reduction as a function of the beam current. The gun brightness reduction must be included when the probe property (the relation between the beam current l(b) and the probe size on the sample, d) of the entire electron optical column is evaluated. Formulas that explicitly consider the gun aberrations into account are presented. It is shown that the probe property curve consists of three segments in the order of increasing beam current: (i) the constant probe size region, (ii) the brightness limited region where the probe size increases as d approximately I(b)(3/8), and (iii) the angular current intensity limited region in which the beam size increases rapidly as d approximately I(b)(3/2). Some strategies are suggested to increase the threshold beam current and to extend the effective beam current range of the point cathode gun into micro ampere regime.