Stereospecific analysis of fish oil triacyl-sn-glycerols

Stereospecific analysis of fish oil triacyl-sn-glycerols was carried out by novel high-performance liquid chromatography on a chiral stationary phase. The positional distributions of fatty acids were determined without accumulation of errors in a particular position and preferential hydrolysis for a particular fatty acid. High-resolution gas-liquid chromatography on an open tubular column detailed the distribution of unsaturated fatty acid isomers having olefinic bonds in different positions. The distribution of fatty acids was not independent of other fatty acids. The distribution of long-chain highly unsaturated fatty acids 22:6(n-3), 22:5(n-3) and 20:5(n-3) was governed by total amounts of 20:1 and 22:1 in triacyl-sn-glycerols. Long-chain monounsaturated acids 20:1 and 22:1 were influenced by the position of the olefinic bond in 20:1 occurring in triacyl-sn-glycerols. Shorter-chain C14-C18 fatty acids seemed to be influenced by total fatty acid composition. These results introduce a concept of mutual interaction between fatty acids to the investigation of positional distribution of fatty acids.     

Magnetic and Transport Properties of Bilayered Perovskite Sr3Ir2O7

We report magnetic and transport properties of polycrystalline samples of bilayered perovskite Sr₃Ir₂O₇, which is synthesized by using high pressure technique. Magnetic susceptibility shows weak ferromagnetism below 290K with small size of remanent moment (10^–3B/Ir). Resistivity shows insulating behavior below 290K. We discuss the magnetism and conductivity in Sr₃Ir₂O₇ comparing with those of Sr₃Ru₂O₇, which has a quite similar crystal structure to Sr₃Ir₂O₇, from the view point of rotation angle of MO₆ (M=Ir, Ru) octahedra.     

Ergodicity of spike trains: when does trial averaging make sense?

Neuronal information processing is often studied on the basis of spiking patterns. The relevant statistics such as firing rates calculated with the peri-stimulus time histogram are obtained by averaging spiking patterns over many experimental runs. However, animals should respond to one experimental stimulation in real situations, and what is available to the brain is not the trial statistics but the population statistics. Consequently, physiological ergodicity, namely, the consistency between trial averaging and population averaging, is implicitly assumed in the data analyses, although it does not trivially hold true. In this letter, we investigate how characteristics of noisy neural network models, such as single neuron properties, external stimuli, and synaptic inputs, affect the statistics of firing patterns. In particular, we show that how high membrane potential sensitivity to input fluctuations, inability of neurons to remember past inputs, external stimuli with large variability and temporally separated peaks, and relatively few contributions of synaptic inputs result in spike trains that are reproducible over many trials. The reproducibility of spike trains and synchronous firing are contrasted and related to the ergodicity issue. Several numerical calculations with neural network examples are carried out to support the theoretical results.     

High-Speed CMOS Track/Hold Circuit Design

This paper describes the design of a high-speed CMOSTrack/Hold circuit in front of an ADC. The Track/Hold circuit employsdifferential open-loop architecture, very linear source follower inputbuffers, NMOS sampling switches and bootstrap sampling-switch drivercircuits for high-speed operation with 3.3 V supply voltage. SPICEsimulations with MOSIS 0.35 m CMOS BSIM3v3 parameters showed thatit achieves a signal-to-(noise+distortion)-ratio (SNDR) of morethan 50 dB for up to 100 MHz sinusoidal input at 200 MS/s with 40 mWpower consumption.     

Structures of ozonolysis products of methyl oleate obtained in a carboxylic acid medium

High-performance liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectrometry (NMR) were applied to the analysis of organic peroxide mixtures, which were labile and tended to decompose during analysis. The ozonolysis reaction of methyl oleate gives a peroxide mixture, and, finally, mono- and dibasic acids are obtained by subsequent oxidation. In this study, methyl oleate was ozonized in a nonanoic acid medium, one of the final reaction products. The reaction products were directly analyzed by LC-MS equipped with a frit-fast atom bombardment interface. The molecular ion peak of each peroxide was clearly observed, and its molecular weight was readily determined. On the other hand, each peroxide was fractionated by high-performance liquid chromatography and submitted to structural analysis by NMR. Both results indicated that the reaction products include four peroxidic species: 1,2,4-trioxolaneI, peroxide oligomerII, 1-acyloxyalkyl-1-hydroperoxideIII, and 1-acyloxyalkyl-1′-hydroxyalkyl peroxideIV, as well as an aldehydeV. Ozonolysis of methyl oleate in the absence of solvent produces mainlyI, while that in the presence of a carboxylic acid solvent characteristically produces mainlyIII andIV derived from the solvent.Bis(1-acyloxyalkyl-1-alkyl) peroxide, which was reported previously as a ozonolysis product of methyl oleate, was concluded to beIV in this study. This work was presented at the 31th Annual Meeting of the Japan Oil Chemists’ Society, 1992, Tokyo, Japan.     

A cautious scheduler for multistep transactions

Given a classC of serializable schedules, a cautiousC-scheduler is an on-line transaction scheduler that outputs schedules in classC and never resorts to rollbacks. Such a scheduler grants the current request if and only if the partial schedule it has granted so far, followed by the current request, can be extended to a schedule inC. A suitable extension is searched among the set of all possible sequences of the pending steps, which are predeclared by the transactions whose first requests have already arrived. If the partial schedule cannot be extended to a schedule inC, then the current request is delayed. An efficient cautiousCPSR-scheduler has been proposed by Casanova and Bernstein.This paper discusses cautiousWRW-scheduling, whereWRW is the largest polynomially recognizable subclass of serializable schedules currently known. Since cautiousWRW-scheduling is, in general, NP-complete as shown in this paper, we introduce, a subclass (namedWRW ^#) ofWRW and discuss an efficient cautiousWRW ^#-scheduler. We also show that the fixed point set of the cautiousWRW ^#-scheduler properly containsCPSR. Therefore, ourWRW ^#-scheduler allows more concurrency than anyCPSR- scheduler.This work was supported in part by the Natural Sciences and Engineering Research Council of Canada under Grant No. A5240 and in part by the Ministry of Education, Science and Culture of Japan under Scientific Research Grant-in-Aid.     

Low-temperature epitaxial growth of conductive LaNiO3 thin films by RF magnetron sputtering

Epitaxial growth of LaNiO₃ (LNO) thin films was successful on CeO₂/YSZ/Si(100), MgO(100) and SrTiO₃ (STO)(100) substrates by RF magnetron sputtering at 300 °C, although pulsed laser deposition requires 600 °C to prepare epitaxial LNO films according to the literature. Epitaxial LNO films deposited on CeO₂/YSZ/Si(100) and STO(100) had single orientation of LNO[100]//CeO₂[110]//YSZ[110]//Si[110]) and LNO[100]//STO[100], respectively. On the other hand, epitaxial LNO films deposited on MgO(100) had mixed orientations of LNO[100]//MgO[100] and LNO[100]//MgO[110]. The lattice parameter, composition and resistivity of the LNO thin films were strongly dependent on the substrate temperature. The minimum resistivity of LNO films was approximately 5×10⁻⁶ Ω m, which value almost agrees with the resistivity in the literature. It was found that the temperature to achieve minimum resistivity was 200 °C, irrespective of the type of substrate. The surface of the LNO films was smooth and flat.