Essential oil constituents and biological activities of Peristrophe bicalyculata and Borreria verticillata

Peristrophe bicalyculata (Retz) Nees (Acanthaceae) or 'The Goddess of Mercy' and Borreria verticillata (L.) G.F.W. Mey., (Rubiaceae), or 'Irawo-Ile' (Yoruba, South-west, Nigeria), are annual herbs, which are poorly exploited. The volatile oils obtained by hydrodistillation in an all glass Clevenger-type apparatus from the plant samples have been investigated by gas chromatography-mass spectrometry (GC-MS). With respect to the oil of P. bicalyculata, beta-caryophyllene (33.9%), alpha-zingiberene (10.4%), germacrene D and globulol (5.0%) were the compounds occurring in abundance. The oil of B. verticillata had an abundance of phytol (56.3%) and 1, 8-cineole (20.4%), with sizeable proportions of alpha-pinene (7.1%) and p-cymene (4.0%). In addition, the volatile oils displayed promising in-vitro antimicrobial activity against the tested micro-organisms, (MIC 12.5-22.3 microg/mL), while only the oil of P. bicalyculata displayed in-vitro cytotoxicity to MCF-7 (human breast tumor) and MDA-MB-468 (human breast tumor) cells. The present investigation may be the first of its kind for the evaluation of the volatile oil constituents of the studied plants.     

Solid-phase microextraction: investigation of the metabolism of substances that may be abused by inhalation

Purified liquefied petroleum gas (LPG), a mixture of butane, isobutane, and propane, is commonly abused by inhalation. Little is known about the mammalian metabolism of these substances. Metabolism of other hydrocarbons, including n-hexane and cyclohexane, has been studied in vitro using a range of liver preparations, with metabolites analyzed by static headspace techniques. Solid-phase microextraction (SPME) for sampling metabolites in the headspace of incubates of volatile compounds with activated rat liver microsomes is investigated. Cyclohexanol and cyclohexanone were formed from cyclohexane and 1-, 2-, and 3-hexanol and 2-hexanone from n-hexane as predicted. Secondary alcohols are found for the other compounds studied, except for propene and isobutane, together with 2-propanone and 2-butanone from propane and n-butane, respectively. Samples from three individuals who died following LPG abuse contained a range of putative n-butane metabolites: n-butanol, 2-butanol, 2,3-butanediol, 3-hydroxy-2-butanone, and 2,3-butanedione. To our knowledge, the last three compounds have not been proposed as metabolites of n-butane in man. These might be produced through similar metabolic pathways to those of n-hexane and n-heptane. The findings indicate the value of SPME for investigating the metabolism of volatile substances and for detecting and monitoring exposure to these compounds.     

Determination of the antiferroquadrupolar order parameters in UPd(3)

By combining accurate heat capacity and x-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd(3). The order parameter of the highest temperature quadrupolar phase has been uniquely determined to be antiphase Q{zx} in contrast to the previous conjecture of Q{x{2}-y{2}}. The azimuthal dependence of the x-ray scattering intensity from the quadrupolar superlattice reflections indicates that the lower temperature phases are described by a superposition of order parameters. The heat capacity features associated with each of the phase transitions characterize their order, which imposes restrictions on the matrix elements of the quadrupolar operators.     

On the Distribution of Sums of Independent Exponential Random Variables Via Wilks’ Integral Representation

In this note we consider an alternative approach to compute the distribution of the sum of independent exponential random variables. In particular, by considering the logarithmic relation between exponential and beta distribution functions and by considering the Wilks’ integral representation for the product of independent beta random variables, we provide a closed-form expression for the distribution of the sum of independent exponential random variables. The expression we obtain is simpler than the ones previously obtained in the literature.     

Femtosecond index change mechanisms and morphology of SiC crystalline materials

Femtosecond lasers have a unique ability of processing bulk transparent materials for various applications such as micromachining, waveguide manufacturing, and photonic bandgap structures just to name a few. These applications depend on the formation of micron or submicron size features that are known to be index modifications to the bulk substrate [H. Guo, H. Jiang, Y. Fang, C. Peng, H. Yang, Y. Li, Q. Gong, J. Opt. A: Pure Appl. Opt. 6 (2004) 787]. To the best of our knowledge the physical understanding of how these index-modified features are formed is still unknown, but many good theories exist such as Petite et al. [G. Petite, P. Daguzan, S. Guizard, P. Martin, in: IEEE Annual Report Conference on Electrical Insulation and Dielectric Phenomena, vol. 15, IEEE, 1995, pp. 40-44] or Tien et al. [A. Tien, S. Backus, H. Kapteyn, M. Murnane, G. Mourou, Phys. Rev. Lett. 82 (1999) 3883]. In this Letter the question on the physical cause for index changes is investigated by the combined efforts between Wright-Patterson AFB (WPAFB) and the University of Dayton (UD) using numerous imaging equipment such as TEM, AFM, NSOM, Nomarski microscopy, X-ray crystallography, Raman spectroscopy, and even diffraction efficiency experiments. With all the combined imaging equipment this research is able to present valuable data and deduce plausible theories of the physics of the index modification mechanism.     

First global observations of atmospheric COClF from the Atmospheric Chemistry Experiment mission

Carbonyl chlorofluoride (COClF) is an important reservoir of chlorine and fluorine in the Earth's atmosphere. Satellite-based remote sensing measurements of COClF, obtained by the Atmospheric Chemistry Experiment (ACE) for a time period spanning February 2004 through April 2007, have been used in a global distribution study. There is a strong source region for COClF in the tropical stratosphere near 27 km. A layer of enhanced COClF spans the low- to mid-stratosphere over all latitudes, with volume mixing ratios of 40-100 parts per trillion by volume, largest in the tropics and decreasing toward the poles. The COClF volume mixing ratio profiles are nearly zonally symmetric, but they exhibit a small hemispheric asymmetry that likely arises from a hemispheric asymmetry in the parent molecule CCl₃F. Comparisons are made with a set of in situ stratospheric measurements from the mid-1980s and with predictions from a 2-D model.     

Surface‐enhanced Raman scattering spectroscopy via gold nanostars

Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface‐enhanced Raman scattering (SERS) spectroscopy. Star‐shaped gold (Au) NPs were prepared in aqueous solutions by the seed‐mediated growth method and tested for Raman enhancement using 2‐mercaptopyridine (2‐MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman enhancement factors (EFs) for 2‐MPy on Au nanostars and nanorods are comparable and estimated as greater than 5 orders of magnitude. However, the enhancement for CV on nanostars was significantly higher than for nanorods, in particular at CV concentrations of 100 nM or lower. This article is a US Government work and is in the public domain in the USA. Published in 2008 by John Wiley & Sons, Ltd.     

Exclusive branching-fraction measurements of semileptonic tau decays into three charged hadrons, into phipi(-)nu tau, and into phi K(-)nu tau

Using a data sample corresponding to an integrated luminosity of 342 fb(-1) collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV, we measure B(tau(-)--> pi(-)pi(-)pi+nu(tau)(ex.K(S0))=(8.83+/-0.01+/-0.13)%, B(tau(-) -->K(-)pi(-)pi+nu tau(ex.K(S0))=(0.273+/-0.002+/-0.009)%, B(tau(-) -->K(-)pi(-)K+nu tau)=(0.1346+/-0.0010+/-0.0036)%, and B(tau(-) -->K(-)K(-)K+nu tau)=(1.58+/-0.13+/-0.12)x10;{-5}, where the uncertainties are statistical and systematic, respectively. These include significant improvements over previous measurements and a first measurement of B(tau(-) -->K(-)K(-)K+nu tau) in which no resonance structure is assumed. We also report a first measurement of B(tau(-) -->var phi(-)nu tau)=(3.42+/-0.55+/-0.25)x10(-5), a new measurement of B(tau(-) -->var phi K(-)nu tau)=(3.39+/-0.20+/-0.28)x10(-5) and a first upper limit on B(tau(-) -->K(-)K(-)K+nu tau(ex.var phi)).     

Observation of Y(3940) --> J/psiomega in B --> J/psiomegaK at BABAR

We present a study of the decays B;{0,+}-->J/psiomegaK;{0,+} using 383x10;{6} BB[over ] events obtained with the BABAR detector at PEP-II. We observe Y(3940)-->J/psiomega, with mass 3914.6_{-3.4};{+3.8}(stat)+/-2.0(syst) MeV/c;{2}, and width 34_{-8};{+12}(stat)+/-5(syst) MeV. The ratio of B0 and B+ decay to YK is 0.27_{-0.23};{+0.28}(stat)-0.01+0.04(syst), and the relevant B0 and B+ branching fractions are reported.