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Selected AbstractsSynthesis, structural and thermal studies of tetrathioureacopper(I) chloride crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005M. Dhandapani Abstract Tetrathioureacopper(I) chloride, hereafter abbreviated as TCC, was synthesised and single crystals were obtained from saturated aqueous solution by slow evaporation (solution growth) method at room temperature. The crystals obtained are bright, colourless and transparent having well defined external faces. The grown crystals were characterized through elemental analysis, single crystal X-ray diffraction study, thermal analysis, electron spin resonance spectroscopy and Fourier Transform infrared spectroscopy. The elemental analysis confirms the stoichiometry of the compound. The single crystal diffraction studies indicate that TCC crystallises in the tetragonal lattice and the unit cell parameters are a = b = 13.4082 Å, c = 13.8074 Å, V = 2482.29 Å3, , = , = , = 90°. Space group and the number of molecules per unit cell (Z) are found to be P41212 and 8 respectively. The TG curve of the sample shows a prolonged decomposition from 210 to 628.3 °C, from which the decomposition pattern has been formulated. The endothermic peaks in the DTA curve indicate melting and decomposition of the compound at 165.2 and 633.8 °C respectively. An exothermic peak in high temperature DSC indicates a phase transition in the compound at 274.8 °C. Thermal anomalies observed in the low temperature DSC at ,163.3, ,152.0, ,141.5, ,108.3, 1.0 and 12.1 °C in the heating run and ,157.1 and ,153.9 °C in the cooling run reveal first order phase transitions in the crystal. The peaks observed at ,146.2 °C in both the heating and cooling runs suggest occurrence of a second order phase transition in this compound. The IR spectroscopic data were used to assign the characteristic vibrational frequencies of various groups present in the compound. The ESR study confirms that the copper is in the +1 oxidation state in the complex. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The climatology of sea breezes on SardiniaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2002M. Furberg Abstract Hourly wind speed and direction data from 12 coastline stations on Sardinia, Italy, are analysed in order to characterize sea breezes in the region. A set of criteria based on the diurnal reversal of wind direction, and the thermal gradient necessary to drive the circulation, is used to identify sea breeze days. Statistics are presented that describe the occurrence, duration, and strength of the sea breezes. On a stationwide basis, sea breezes are most frequent in the summer months (May,August), when they appear on more than one-third of the days. Sea breeze occurrence and duration are the greatest for the stations on the east coast of the island. The all-station average sea breeze duration reaches a maximum of about 9 h in June. The strength of the sea breezes is roughly 3 m s,1 during summer months on average over all stations in the sample. An analysis of mean daily hodographs for the stations in the sample shows clearly the onshore,offshore nature of the sea breeze circulation, and the response of the sea breezes to the local coastline. Sea breezes are shown to develop simultaneously on all coasts of the island under appropriate synoptic conditions. Copyright © 2002 Royal Meteorological Society. [source] Aspects of the modelling of the radial distribution function for small nanoparticlesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2007Vladimir I. Korsunskiy An approach to modelling radial distribution functions (RDFs) of nanoparticle samples over a wide range of interatomic distances is presented. Two different types of contribution to the model RDF are calculated. The first explicitly reflects the structure of the nanoparticle parts with more or less crystalline atomic structure. It can be calculated precisely and contains comparatively sharp peaks, which are produced by the set of discrete interatomic distances. The second includes RDF contributions from distances between weakly correlated atoms positioned within different nanoparticles or within different parts of a nanoparticle model. The calculation is performed using the approximation of a uniform distribution of atoms and utilizes the ideas of the characteristic functions of the particle shape known in small-angle scattering theory. This second RDF contribution is represented by slowly varying functions of interatomic distance r. The relative magnitude of this essential part of the model RDF increases with increasing r compared with the part that represents the ordered structure. The method is applied to test several spherical and core/shell models of semiconductor nanoparticles stabilized with organic ligands. The experimental RDFs of ZnSe and CdSe/ZnS nanoparticle samples were obtained by high-energy X-ray diffraction at beamline BW5, HASYLAB, DESY. The ZnSe nanoparticles have a spherical core with approximately 26,Å diameter and zincblende structure. The RDF of the CdSe/ZnS nanoparticle sample shows resolved peaks of the first- and the second-neighbour distances characteristic for CdSe (2.62 and 4.27,Å) and for ZnS (2.33 and 3.86,Å) and for the first time clearly confirms the presence of CdSe and ZnS nanophases in such objects. The diameters of the CdSe and ZnS spherical cores are estimated as 27 and 15,Å. CdSe and ZnS are present in the sample for the most part as independent nanoparticles. A smaller amount of ZnS forms an irregularly shaped shell around the CdSe cores, which consists of small independently oriented ZnS particles. [source] Non-parametric permutation test for the discrimination of float glass samples based on LIBS spectraJOURNAL OF CHEMOMETRICS, Issue 6 2010Erin McIntee Abstract Laser-induced breakdown spectroscopy (LIBS) coupled with non-parametric permutation based hypothesis testing is demonstrated to have good performance in discriminating float glass samples. This type of pairwise sample comparison is important in manufacturing process quality control, forensic science and other applications where determination of a match probability between two samples is required. Analysis of the pairwise comparisons between multiple LIBS spectra from a single glass sample shows that some assumptions required by parametric methods may not hold in practice, motivating the adoption of a non-parametric permutation test. Without rigid distributional assumptions, the permutation test exhibits excellent discriminating power while holding the actual size of Type I error at the nominal level. Copyright © 2010 John Wiley & Sons, Ltd. [source] Dust emission in the far-infrared as a star formation tracer at z= 0: systematic trends with luminosityMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2003D. Pierini ABSTRACT We investigate whether dust emission in the far-infrared (far-IR) continuum provides a robust estimate of the star formation rate (SFR) for a nearby, normal late-type galaxy. We focus on the ratio of the 40,1000 ,m luminosity (Ldust) to the far-ultraviolet (far-UV) (0.165 ,m) luminosity, which is connected to recent episodes of star formation. Available total photometry at 0.165, 60, 100 and 170 ,m limits the statistics to 30 galaxies, which, however, span a large range in observed (and, thus, attenuated by dust) K -band (2.2 ,m) luminosity, morphology and inclination (i). This sample shows that the ratio of Ldust to the observed far-UV luminosity depends not only on i, as expected, but also on morphology and, in a tighter way, on observed K -band luminosity. We find that Ldust/LFUV, eLK0.62, where LFUV and LK are the unattenuated stellar luminosities in far-UV and K, respectively, and , is the ratio of the attenuation optical depths at 0.165 ,m (,FUV) and 2.2 ,m (,K). This relation is to zeroth order independent of i and morphology. It may be further expressed as Ldust/LFUV,L,K, where ,= 0.61 , 0.02,, under the observationally motivated assumption that, for an average inclination, e,L,0.02K. We adopt calculations of two different models of attenuation of stellar light by internal dust to derive solid-angle-averaged values of ,. We find that , is positive and decreases towards 0 from the more luminous to the less luminous galaxies. This means that there is no universal ratio of far-IR luminosity to unattenuated far-UV luminosity for nearby, normal late-type galaxies. The far-IR luminosity systematically overestimates SFR in more luminous, earlier-type spirals, owing to the increased fractional contribution to dust heating of optical/near-IR photons in these objects. Conversely, it systematically underestimates SFR in fainter, later-type galaxies, the ,FUV of which is reduced. The limited statistics and the uncertainty affecting the previous scaling relations do not allow us to establish quantitative conclusions, but an analogous analysis making use of larger data sets, available in the near future (e.g. from GALEX, ASTRO-F and SIRTF), and of more advanced models will allow a quantitative test of our conclusions. [source] Narrow-band CCD photometry of giant H ii regionsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2002Guillermo Bosch We have obtained accurate CCD narrow-band H, and H, photometry of giant H ii regions (GEHRs) in M33, NGC 6822 and M101. Comparison with previous determinations of emission-line fluxes shows large discrepancies; their probable origins are discussed. Combining our new photometric data with global velocity dispersion (,) derived from emission linewidths, we review the relation. A re-analysis of the properties of the GEHRs included in our sample shows that age spread and the superposition of components in multiple regions introduce a considerable spread in the regression. Combining the information available in the literature regarding ages of the associated clusters, evolutionary footprints on the interstellar medium, and kinematical properties of the knots that build up the multiple GEHRs, we find that a subsample , which we refer to as young and single GEHRs , do follow a tight relation in the plane. [source] Crystallization and biodegradation of polylactide/carbon nanotube compositesPOLYMER ENGINEERING & SCIENCE, Issue 9 2010Defeng Wu The crystallization behavior of polylactide/carbon nanotube composites was studied using differential scanning calorimeter and polarized optical microscope. The nucleation mechanisms and the crystallization kinetics were explored. The results show that the presence of nanotubes has nucleating effect on both the melt crystallization and the cold crystallization of PLA. However, the nanotubes also play the role of physical barrier, impeding the crystal growth dynamically. In the experimental range of temperatures, the presence of nanotubes accelerates the melt crystallization, while retards the overall kinetics of the cold crystallization. The biodegradability of the samples with various crystallization histories was then further examined. The results show that the presence of nanotubes reduces the biodegradation rate of PLA, and the amorphous sample shows the highest degradation levels. Moreover, a lower degradation level is observed both on the surface and inside the sample with melt crystallization history in contrast to the one with cold crystallization history. POLYM. ENG. SCI., 50:1721,1733, 2010. © 2010 Society of Plastics Engineers [source] Unique ramus anatomy for Neandertals?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2005Milford H. Wolpoff Abstract The ramus of Neandertal mandibles is said to show a suite of uniquely Neandertal character states that demonstrate the independent course of Neandertal evolution. This is the latest of numerous attempts to define cranial and mandibular autapomorphies for Neandertals. We examine variation in the four presumably autapomorphic ramal features and show they are neither monomorhic within Neandertals (to the contrary Neandertals are at least as variable as other human samples) nor unique to Neandertals, since they regularly appear in populations predating and postdating them. Neandertals differ from other human populations, both contemporary and recent, but the question of whether this fact reflects a divergent evolutionary trajectory must be addressed by the pattern of differences. In this case, as in the other attempts to establish Neandertal autapomorphies, rather than showing restricted variation and increased specialization, the Neandertal sample shows that the range of human variation in the recent past encompasses, and in some cases exceeds, human variation today, even in the very features claimed to be autapomorphic. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc. [source] Optical and thermo electrical properties of ZnO nano particle filled polystyreneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Mulayam S. Gaur Abstract The study of optical and thermally stimulated electrical properties such as optical band gap, refractive index, X-ray spectra, SEM spectra, thermally stimulated discharge current (TSDC), differential scanning calorimetry (DSC) have been undertaken in ZnO nanoparicle filled polystyrene nanocomposite thin film of 30 ,m thickness. The appearance of single TSDC peak at temperature 408 ± 5 K in nanocomposite samples shows the charge carriers injected from deeper trapping levels. It is due to the modification of surface and bulk properties of polystyrene by filling of ZnO nanoparticles. In other hand, the strong interaction of nanoparticles with polymer matrix is the expected reason of improvement of crystallite size, optical energy band gap, refractive index, TSDC, glass transition temperature, and charge storage. It is confirmed from SEM images that the modifications of these properties are caused by creation of clusters in amorphous,crystalline boundaries of pristine polystyrene. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Mid-Holocene and glacial-maximum vegetation geography of the northern continents and AfricaJOURNAL OF BIOGEOGRAPHY, Issue 3 2000I. Colin Prentice Abstract BIOME 6000 is an international project to map vegetation globally at mid-Holocene (6000 14C yr bp) and last glacial maximum (LGM, 18,000 14C yr bp), with a view to evaluating coupled climate-biosphere model results. Primary palaeoecological data are assigned to biomes using an explicit algorithm based on plant functional types. This paper introduces the second Special Feature on BIOME 6000. Site-based global biome maps are shown with data from North America, Eurasia (except South and Southeast Asia) and Africa at both time periods. A map based on surface samples shows the method's skill in reconstructing present-day biomes. Cold and dry conditions at LGM favoured extensive tundra and steppe. These biomes intergraded in northern Eurasia. Northern hemisphere forest biomes were displaced southward. Boreal evergreen forests (taiga) and temperate deciduous forests were fragmented, while European and East Asian steppes were greatly extended. Tropical moist forests (i.e. tropical rain forest and tropical seasonal forest) in Africa were reduced. In south-western North America, desert and steppe were replaced by open conifer woodland, opposite to the general arid trend but consistent with modelled southward displacement of the jet stream. The Arctic forest limit was shifted slighly north at 6000 14C yr bp in some sectors, but not in all. Northern temperate forest zones were generally shifted greater distances north. Warmer winters as well as summers in several regions are required to explain these shifts. Temperate deciduous forests in Europe were greatly extended, into the Mediterranean region as well as to the north. Steppe encroached on forest biomes in interior North America, but not in central Asia. Enhanced monsoons extended forest biomes in China inland and Sahelian vegetation into the Sahara while the African tropical rain forest was also reduced, consistent with a modelled northward shift of the ITCZ and a more seasonal climate in the equatorial zone. Palaeobiome maps show the outcome of separate, independent migrations of plant taxa in response to climate change. The average composition of biomes at LGM was often markedly different from today. Refugia for the temperate deciduous and tropical rain forest biomes may have existed offshore at LGM, but their characteristic taxa also persisted as components of other biomes. Examples include temperate deciduous trees that survived in cool mixed forest in eastern Europe, and tropical evergreen trees that survived in tropical seasonal forest in Africa. The sequence of biome shifts during a glacial-interglacial cycle may help account for some disjunct distributions of plant taxa. For example, the now-arid Saharan mountains may have linked Mediterranean and African tropical montane floras during enhanced monsoon regimes. Major changes in physical land-surface conditions, shown by the palaeobiome data, have implications for the global climate. The data can be used directly to evaluate the output of coupled atmosphere-biosphere models. The data could also be objectively generalized to yield realistic gridded land-surface maps, for use in sensitivity experiments with atmospheric models. Recent analyses of vegetation-climate feedbacks have focused on the hypothesized positive feedback effects of climate-induced vegetation changes in the Sahara/Sahel region and the Arctic during the mid-Holocene. However, a far wider spectrum of interactions potentially exists and could be investigated, using these data, both for 6000 14C yr bp and for the LGM. [source] Influence of La doping on the properties of molybdenum perovskite Sr1,xLaxMoO3 (0 , x , 0.2)PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2006S. B. Zhang Abstract The effects of La-doping on the structural, magnetic, electrical transport and specific-heat properties in 4d perovskites Sr1,xLaxMoO3 (0 , x , 0.2) have been investigated. The substitution of Sr ions by La ions does not change the space group of the samples, but increases the lattice parameter a (Å). The resistivity , and magnetic susceptibility , decrease monotonously with the increase of x , while the electronic specific heat coefficient ,e increases. The resistivity of all samples shows a T2 dependence in the low-temperature region of 2 K < T < 125 K and a T dependence in the high-temperature range of 130 K < T < 350 K, related to the electron,electron (e,e) and electron,phonon (e,ph) scattering, respectively. The specific-heat data agrees with the classical Dulong,Petit phonon specific heat, Ccl = 3kBrNA = 124.7 J/mol K at high temperatures and Cp(T )/T = ,e + ,pT2 at low temperatures. These behaviors can be explained according to the decrease of the density of states (DOS) at the Fermi energy level (EF), N (EF). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Genotype Frequencies of Selected Drug Metabolizing Enzymes and ABC Drug Transporters among Breast Cancer Patients on FAC ChemotherapyBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2010Nasir Ali Afsar With some exemptions, single nucleotide polymorphisms in such genes, however, are not known to be susceptibility factors for breast cancer. This study explored genotype profiles for the breast cancer patients on fluorouracil, doxorubicin and cyclophosphamide (FAC) in a Pakistani set of population and their comparison with HapMap data. Sixty-eight female breast cancer patients were included. All received FAC chemotherapy. Relevant genotyping was done either through restriction fragment length polymorphism or pyrosequencing. The variant allele frequencies were: 5.1% for CYP2C9*2 (430C>T), 15.4% for CYP2C9*3 (1075A>C), 27.2% for CYP2C19*2 (681G>A), 33.1% for GSTA1*B (-69C>T, -52G>A), 62.5% for ALDH3A1*2 (985C>G), 58.8% and 4.4% for ABCB1 (2677 G>T/A), 64.7% for ABCB1 3435 C>T, and 15.4%, 33.1% and 39.7% for ABCC2 (,24 C>T, 1249 G>A and 3972 C>T). In comparison with HapMap, this first exploration in Pakistani samples shows higher frequency of (i) CYP2C9*3 carriers (p < 0.05) than in Hispanic, Chinese, Japanese and African samples, (ii) ALDH3A1*2 carriers (p < 0.01) than Caucasian, Hispanic, Chinese, Japanese and African samples. For ABC transporters, a higher frequency of variant allele was observed in (iii) ABCB1 2677 G>T/A (p < 0.01) than Caucasian, Hispanic and African, (iv) ABCB1 3435 C>T (p < 0.05) than Chinese, Japanese and African, (v) ABCC2 1249 G>A (p < 0.01) than Hispanic, Chinese and Japanese samples. In conclusion, cyclophosphamide activation and detoxification of reactive intermediates may be altered in the Pakistani. Though carriers of CYP2C19*2 were higher than in Caucasian and Hispanics, they did not reach statistical significance (p = 0.05). [source] | ||||||||||||||||