Simulation model for shapiro time delay and light deflection experiments

The time delay experiment proposed by I.I. Shapiro in 1964 and conducted in the seventies was the most precise experiment of general relativity until that time. Further experimentation has improved the accuracy level of both the time delay and the light deflection experiments. A simulation model is proposed that involves only a simple mass and time transformation factor involving velocity of light. The light deflection and the time delay experiments are numerically simulated using this model that does not use the general relativistic equations. The computed values presented in this paper compare well with recent levels of accuracy of their respective experimental results.     

Thermal stability evaluation of methylic biodiesel obtained for different oilseeds

Biodiesel is defined as a mixture of mono- or di-alquil esters of vegetable oil or animal fats. During long-term storage, oxidation caused by contact with air (autoxidation) presents a legitimate concern in relation to monitoring and maintaining fuel quality. Extensive oxidative degradation may compromise the quality by adversely affecting kinematic viscosity, acid value, or peroxide value. The oxidation susceptibility of biodiesel, due to the presence of triacilglycerides of poly-unsaturated fatty acids, was evaluated in this study. Samples of sunflower, castor, and soybean biodiesels were obtained through the transesterification reaction, with the intention of achieving the thermal stability study through thermogravimetrical analyses and differential scanning calorimetry high pressure. It was furthermore observed through thermogravimetry and pressure differential scanning calorimetry curves that castor biodiesel exhibited the highest thermal and oxidative stability.     

Pressure-induced phase transformations in LiAlH4

The pressure-induced phase transformations in pure LiAlH4 have been studied using in situ Raman spectroscopy up to 7 GPa. The analyses of Raman spectra reveal a phase transition at approximately 3 GPa from the ambient pressure monoclinic alpha-LiAlH4 phase (P2(1)/c) to a high pressure phase (beta-LiAlH4, reported recently to be monoclinic with space group I4(1)/b) having a distorted [AlH4]- tetrahedron. The Al-H stretching mode softens and shifts dramatically to lower frequencies beyond the phase transformation pressure. The high pressure beta-LiAlH4 phase was pressure quenchable and can be recovered at lower pressures ( approximately 1.2 GPa). The Al-H stretching mode in the quenched state further shifts to lower frequencies, suggesting a weakening of the Al-H bond.     

Schur complement preconditioners for anisotropic problems

We present two new variants of Schur complement domain decompositionpreconditioners suitable for 2D anisotropic problems. Thesevariants are based on adaptations of the probing idea, describedby Chan et al (1992 Fifth Int. Symp. on Domain DecompositionMethods for Partial Differential Equations, Philadelphia: SIAM,pp 236-249), used in conjunction with a coarse grid approximationas introduced by Bramble et al (1986 Math. Comput. 47, 103-134).The new methods are specifically designed for situations wherethe coupling between neighbouring interfaces is stronger thanthe coupling within an interface. Taking into account this strongcoupling, one variant uses a multicolour probing technique toavoid distortion in the probe approximations that appear whenusing the method proposed by Chan et al. The second techniqueuses additional probe matrices to approximate not only the couplingwithin the interfaces but also the coupling between interfacepoints across the subdomains. This latter procedure looks somewhatlike an alternating line relaxation method for anisotropic problems,see Brandt (1977 Math. Comput.. 31, 333-390). To assess therelevance of the new preconditioners, we compare their numericalbehaviour with well known robust preconditioners such as thebalanced Neumann-Neumann method proposed by Mandel (1993 Commun.Numer. Methods Eng.. 9, 233-241).     

评《马氏决策过程》

（《马氏决策过程》,侯振挺、郭先平著,长沙,湖南科技出版社,1997,中文版,386页,定价：28元）马尔可夫决策过程是概率论的运筹学的理论研究和实际应用中极其重要的领域之一．随着中国和国际上对马尔可夫决策过程（MarkovDecisionProcesses,简记为MDP）研究的新进展,许     

Simulation model for anomalous precession of the perihelion of mercury's orbit

The ‘anomalous perihelion precession’ of Mercury, announced by Le Verrier in 1859, was a highly controversial topic for more than half a century and invoked many alternative theories until 1916, when Einstein presented his theory of general relativity as an alternative theory of gravitation and showed perihelion precession to be one of its potential manifestations. As perihelion precession was a directly derived result of the full General Theory and not just the Equivalence Principle, Einstein viewed it as the most critical test of his theory. This paper presents the computed value of the anomalous perihelion precession of Mercury's orbit using a new relativistic simulation model that employs a simple transformation factor for mass and time, proposed in an earlier paper. This computed value compares well with the prediction of general relativity and is, also, in complete agreement with the observed value within its range of uncertainty. No general relativistic equations have been used for computing the results presented in this paper.     

Aminobenzohydrazide based colorimetric and ‘turn-on’ fluorescence chemosensor for selective recognition of fluoride

Chemosensors based on aminobenzohydrazide Schiff bases bearing pyrene/anthracene as fluorophores have been designed and synthesized for F⁻ ion recognition. The addition of fluoride ions to the receptors causes a dramatically observable colour change from pale yellow to brown/red. ¹H NMR studies confirm that the F⁻ ion facilitates its recognition by forming hydrogen bond with hydrogens of amide and amine groups. Moreover these sensors have also been successfully applied to detection of fluoride ion in commercial tooth paste solution.     

The phase diagram of ammonium nitrate

The pressure-temperature (P-T) phase diagram of ammonium nitrate (AN) [NH(4)NO(3)] has been determined using synchrotron x-ray diffraction (XRD) and Raman spectroscopy measurements. Phase boundaries were established by characterizing phase transitions to the high temperature polymorphs during multiple P-T measurements using both XRD and Raman spectroscopy measurements. At room temperature, the ambient pressure orthorhombic (Pmmn) AN-IV phase was stable up to 45 GPa and no phase transitions were observed. AN-IV phase was also observed to be stable in a large P-T phase space. The phase boundaries are steep with a small phase stability regime for high temperature phases. A P-V-T equation of state based on a high temperature Birch-Murnaghan formalism was obtained by simultaneously fitting the P-V isotherms at 298, 325, 446, and 467 K, thermal expansion data at 1 bar, and volumes from P-T ramping experiments. Anomalous thermal expansion behavior of AN was observed at high pressure with a modest negative thermal expansion in the 3-11 GPa range for temperatures up to 467 K. The role of vibrational anharmonicity in this anomalous thermal expansion behavior has been established using high P-T Raman spectroscopy.     

Simultaneous quantitation of IC87114, roflumilast and its active metabolite roflumilast N‐oxide in plasma by LC‐MS/MS: application for a pharmacokinetic study

A sensitive and reliable high‐performance liquid chromatography–mass spectrometry (LC–MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N‐oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid–liquid extraction and separated on a reverse phase C₁₈ column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1–60 ng.mL^?1 for RFM and RFN and 6 to 2980 ng.mL^?1 for IC87114. Intra‐ and inter‐day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r²) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug–drug interaction study in Wistar rats. Copyright © 2012 John Wiley & Sons, Ltd.