bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical determination of coloured zoned minerals in ‘natural stones’ by EDS/WDS electron microprobe: an example from dumortierite quartzites
Authors: Borghi Alessandro , Cossio Roberto , Fiora Laura , Olmi Filippo , Vaggelli Gloria 
Published: January 2004

AbstractDumortierite is a rather uncommon borosilicate [(Al1−x□x) Al2Al4Si3BO18−3x(OH)3x] occurring in rare and precious commercial ‘natural stones’ which hold an economic interest related to their properties and colour. These stones are petrographically known as quartzites, whose blue colour is given by variable amounts of dumortierite. A petrographic and mineral chemistry study of blue dumortierite quartzites from Brazil, Mozambique and Madagascar mines, in order to elucidate the relationships between colour and chemical variations, was performed.Two different dumortierite generations were detected. The first occurs as millimetric porphyroblasts from the Mozambique sample and shows a marked zoning for Al, Si, Ti and Sb. The second is characterised by submillimetric prismatic crystals, which are lesser zoned. For both generations, a good correlation between Ti concentration zoning and pleochroism variations was observed. In particular, the comparison between polarised light images of single dumortierite crystals and the Ti distribution X‐ray maps evidences the good correlation existing between Ti content and blue colour variations. Moreover, dumortierite from Mozambique quartzites displays an unusual occurrence of Sb, with concentrations ranging up to 5 wt.% (expressed as Sb2O3). Copyright © 2003 John Wiley & Sons, Ltd.
Identification of overglaze and underglaze cobalt decoration of ceramics from Valencia (Spain) by portable EDXRF spectrometry
Authors: Roldán C. , Coll J. , Ferrero J. L. , Juanes D. 
Published: January 2004

AbstractThe purpose of this work is the application of non‐destructive analysis to differentiate underglaze and overglaze techniques used in the decoration of glazed ceramics from Valencia (Spain). This study was carried out by portable EDXRF spectrometry using an X‐ray tube and a thermoelectrically cooled semiconductor detector. From the EDXRF spectra we have identified the main elements present in the tin‐opacified lead glaze and in the cobalt pigments. The identification of the underglaze and overglaze decoration is based on the different ratios between the fluorescence line of the main component of the glaze (Pb‐Lα line) and the fluorescence lines of the main components of the pigment (Co‐Kα, Mn‐Kα, Ni‐Kα, … lines) when the incident angle of the X‐ray beam varies. If the position of the detector is fixed, these ratios (Pb/Co, Pb/Mn, Pb/Ni, …) increase with the angle for underglaze decoration, and decrease for overglaze decoration. Copyright © 2003 John Wiley & Sons, Ltd.
Application of the TXRF method to the elemental analysis of cerebrospinal fluid in amyotrophic lateral sclerosis
Authors: Ostachowicz B. , Boruchowska M. , Lankosz M. , Tomik B. , Szczudlik A. , Adamek D. 
Published: January 2004

AbstractThe total reflection x‐ray fluorescence technique was applied to the determination of the elemental composition of cerebrospinal fluid (CSF) in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Samples of the CSF from two groups of patients, ALS and control, were analysed. Two methods of sample preparation were tested in order to improve the detection limits of the analysed elements. The elements Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Rb and Rb were found and determined. Differences in the concentrations of Zn and Cl were found between the ALS and the control group. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of the elemental composition of aortic valve cusps by EDXRF
Authors: Wróbel A. , Goncerz G. , Kunz J. , Podolec P. , Rokita E. 
Published: January 2004

AbstractThe aim of these studies was to develop a procedure for the determination of elemental concentrations in aortic valve cusps based on XRF measurements and to evaluate whether the XRF method may be useful in mineralization studies. The investigations were conducted on aortic valves collected at autopsy from 12 donors. Concentrations of 14 elements (Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Ni, Cu, Zn and Sr) were determined. The cusp areal density determination was based on Compton scattering measurement. Calcium concentration was considered as an indicator of mineralization development. The results revealed differences in the elemental compositions of the cusps constituting one aortic valve for donors older than ∼40 years, whereas no differences were observed in younger donors. There was a correlation between advancement of the mineralization process in the aortic valves, assessed by the Ca concentration, and donors' age. Acceleration of the process was observed for subjects older than 40 years. It may be concluded that homografts should be collected from donors younger than 40 years. Copyright © 2004 John Wiley & Sons, Ltd.
Synchrotron microprobe determination of the elemental distribution in human teeth of the Neolithic period
Authors: Carvalho M. L. , Marques J. P. , Marques A. F. , Casaca C. 
Published: January 2004

AbstractThe purpose of the present work was to investigate whether the distribution of trace elements in human teeth of the Neolithic period in Portugal can reflect environmental conditions, dietary habits and uptake of some elements from the surrounding soil. An x‐ray fluorescence set‐up with microprobe capabilities, installed at the LURE synchrotron (France), was used for elemental analysis of teeth. The resolution of the synchrotron microprobe was 100 µm and the energy of the incident beam was 18 keV. The synchrotron microprobe concentration profiles for V, Mn, Fe, Cu, Zn, Sr and Pb in different regions of the tooth are discussed and correlated with the results obtained by cranio‐facial studies. The Mn and Fe concentrations were much higher in Neolithic teeth than in those of present humans. This may suggest uptake of both elements from the soil. Low concentration levels of Sr were found, which can be correlated with dietary habits. Moreover, the Pb concentration was very low in all the teeth analysed, in agreement with the low pollution levels of this element in this population. All samples were analysed without any chemical preparation. Copyright © 2004 John Wiley & Sons, Ltd.
Proton‐induced x‐ray emission using 68 MeV Protons
Authors: Denker A. , Opitz‐Coutureau J. 
Published: January 2004

AbstractThe x‐ray production cross‐sections for the K lines of heavy elements is large enough at 68 MeV proton energy to detect heavy elements via the K in addition to their L x‐rays. The large proton penetration range and the fact that the absorption coefficients for the x‐ray K lines are much smaller than for the L lines result in an analytical depth of several millimeters. The intensity ratio between the stimulated x‐ray L and K lines yields information about the physical composition (e.g. layered structure, layer sequence, hidden structure elements) of the samples supplementary to their chemical composition. Also, based on the now detectable K lines, spectra with mixtures of heavy elements are easier to evaluate, as the K lines will overlap less than the L lines. The experimental set‐up and several examples of measurements on archaeological and art historical objects are presented. Copyright © 2004 John Wiley & Sons, Ltd.
High energy resolution XRMF spectrometer using polycapillary x‐ray optics and PSPC
Authors: Ding Xunliang , Liu Zhiguo , Yan Yiming , Pan Qiuli 
Published: January 2004

AbstractA new spectrometer based on a plane crystal wavelength dispersive method using a position‐sensitive proportional counter (PSPC) in conjunction with an x‐ray microbeam formed by a monolithic polycapillary x‐ray focusing lens has been developed. The new spectrometer could be used for x‐ray microfluorescence (XRMF) analysis with high sensitivity, high spatial resolution and energy resolution simultaneously. The minimum spot size of the x‐ray beam focused by the lens is 50 µm for Cu Kα. An energy resolution of 4.4 eV is obtained for Ti Kα by means of the spectrometer. The detectable energy range of the spectrometer in one run without a scanning procedure is more than 800 eV. Some results of sample analysis with the spectrometer are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Assessing scattering effects in annular radioisotope excited XRF
Authors: Padilla Alvarez Román , Van Espen Pierre , Abrahantes Quintana Arian 
Published: January 2004

AbstractRayleigh and Compton scattered radiation is used in various correction procedures for quantitative x‐ray fluorescence analysis. However, the information derived from the measured scatter peaks is altered by several phenomena in the case of annular radioisotope excitation, causing the calculated results to deviate, often significantly, from the expected values. In this work, we assessed the main sources of inaccuracy when using measured scatter intensities. Monte Carlo simulation was used to trace the radiation transport in the geometric arrangement source–sample–collimator–detector and to estimate the contribution of different effects to the measured Rayleigh and Compton scatter peaks. The information obtained in this way was used to extend the IAEA–QXAS standardless fundamental parameter approach to the case of annular radioisotope excitation and to formulate a method to correct for spurious fluorescent peaks appearing in blank measurements. Copyright © 2004 John Wiley & Sons, Ltd.
Isolation and characterization of Candida albicans homologue of RAP1, a repressor and activator protein gene in Saccharomyces cerevisiae.
Authors: Uemura Hiroshi , Watanabe‐Yoshida Miyuki , Ishii Nobuya , Shinzato Tomoko , Haw Robin , Aoki Yuko 
Published: January 2004

AbstractTo study the function of RAP1, a Candida albicans gene (CaRAP1) that shows sequence similarity to RAP1 of Saccharomyces cerevisiae was isolated by colony hybridization. DNA sequencing predicted an open reading frame of 429 amino acids with an overall identity of 24% to the ScRap1p. The DNA binding domain (DBD) was highly conserved, and EMSA using a GST–CaRap1p fusion protein confirmed its binding ability to the RPG‐box of S. cerevisiae ENO1. In contrast, the N‐terminus was less conserved and a moderate homology was observed in the BRCT domain. Interestingly, CaRap1p did not contain the C‐terminal activation/repression region of ScRap1p. Its DDBJ/EMBL/GenBank Accession No. is AB036055. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of an UDP‐Glc:glycoprotein glucosyltransferase in the yeast Yarrowia lipolytica
Authors: Babour A. , Beckerich J.‐M. , Gaillardin C. 
Published: January 2004

AbstractThe UDP‐Glc:glycoprotein glucosyltransferase (UGT) is a soluble protein of the endoplasmic reticulum (ER) that plays a determining part in the mechanism by which unfolded, partially folded or misfolded glycoproteins are retained into the ER. We have identified an UGT in the yeast Yarrowia lipolytica. This protein, of a predicted molecular weight of 165.7 kDa, is encoded by a 5054 bp coding sequence containing a 643 bp intron at position 682–1323. The N‐terminal part of the protein displays a signal sequence whereas its C‐terminal part carries an ER retrieval signal HDEL. An interruption of the gene that removes the 1075 last nucleotides of its sequence did not lead to any evident phenotype except for a slight increased sensitivity to tunicamycin. YlUGT1 mRNA levels respond to tunicamycin treatment by an induction factor of 2–4, which indicates that the gene product participates in the quality control mechanism in this yeast. Finally, an immunofluorescence study of the protein localization, shows that the protein distribution is different from that of previously studied ER resident proteins. This could indicate that UGT distribution in the secretory pathway is not confined to the ER. Copyright © 2003 John Wiley & Sons, Ltd.
Alanine : glyoxylate aminotransferase of Saccharomyces cerevisiae–encoding gene AGX1 and metabolic significance
Authors: Schlösser Thomas , Gätgens Cornelia , Weber Ulrike , Stahmann K.‐Peter 
Published: January 2004

AbstractAlanine : glyoxylate aminotransferase is one of three different enzymes used for glycine synthesis in Saccharomyces cerevisiae. The open reading frame YFL030w (named AGX1 in the following), encoding this enzyme, was identified by comparing enzyme specific activities in knockout strains. While 100% activity was detectable in the parental strain, 2% was found in a YFL030w::kanMX4 strain. The ORF found at that locus was suspected to encode alanine : glyoxylate aminotransferase because its predicted amino acid sequence showed 23% identity to the human homologue. Since the YFL030w::kanMX4 strain showed no glycine auxtrophic phenotype, AGX1 was replaced by KanMX4 in a Δ GLY1Δ SHM1Δ SHM2 background. These background mutations, which cause inactivation of threonine aldolase, mitochondrial and cytosolic serine hydroxymethyltransferase, respectively, lead to a conditional glycine auxotrophy. This means that growth is not possible on glucose but on ethanol as the sole carbon source. Additional disruption of AGX1 revealed a complete glycine auxotrophy. Complementation was observed by transformation with a plasmid‐encoded AGX1. Copyright © 2003 John Wiley & Sons, Ltd.
The high general stress resistance of the Saccharomyces cerevisiae fil1 adenylate cyclase mutant (Cyr1Lys1682) is only partially dependent on trehalose, Hsp104 and overexpression of Msn2/4‐regulated genes
Authors: Versele Matthias , Thevelein Johan M. , Van Dijck Patrick 
Published: January 2004

AbstractThe initiation of fermentation in the yeast Saccharomyces cerevisiae is associated with a rapid drop in general stress resistance. Previously we identified a mutant which is deficient in fermentation‐induced loss of stress resistance (fil1), as a partially inactivating mutant in adenylate cyclase. We have now investigated possible causes of its high stress resistance. Deletion of the TPS1 gene, encoding the first enzyme in the biosynthesis of trehalose, or the heat shock protein gene HSP104 only resulted in a minor effect on heat stress resistance compared with deletion of these genes in a wild‐type background. A strain with a deletion of both genes still showed a higher stress resistance in the fil1 background compared to the corresponding wild‐type background. Deletion of the transcription factor genes MSN2 and MSN4, which are required for the expression of STRE‐regulated genes, resulted in a dramatic drop in heat resistance in the wild‐type background but had much less effect in the fil1 mutant. The fil1 msn2Δmsn4Δ strain remained more heat‐resistant than a wild‐type strain. A strain in which all four genes, TPS1, HSP104, MSN2 and MSN4, are deleted was very sensitive to heat stress and also to oxidative and salt stress. Presence of the fil1 mutation in such a strain, however, still clearly enhanced heat, oxidative and salt stress resistance. These results indicate that, in addition to trehalose, Hsp104 and the Msn2/4‐controlled genes, other factors exist in S. cerevisiae that can, significantly and independently of the known factors, enhance general stress resistance. The mutants described in this work provide a tool to identify these novel components. Copyright © 2003 John Wiley & Sons, Ltd.
Ein ungewöhnlicher ambivalenter Zinn(II)‐oxo‐Cluster
Authors: Niemeyer Mark 
Published: January 2004

AbstractDie Umsetzung des Kupferaryls CuDmp (Dmp = 2, 6‐Mes2C6H3; Mes = 2, 4, 6‐Me3C6H2) mit dem Stannandiyl Sn{1, 2‐(tBuCH2N)2C6H4} führt nach langsamer Hydrolyse in Gegenwart von Lithium‐tert‐butanolat mit geringer Ausbeute zu dem Zinn(II)‐oxo‐Cluster {(Et2O)(LiOtBu)(SnO)(CuDmp)}2 (5). Die Festkörperstruktur der farblosen Verbindung zeigt ein zentrales Li2Sn2O2(OtBu)2‐Fragment mit Heterocubanstruktur. Zusätzlich werden die Li‐Akzeptor‐ und O(Sn)‐Donoratome zur Koordination von je einem Molekül Diethylether und Kupferaryl CuDmp benutzt.
A New Octadecanuclear Copper(II)‐Lanthanide(III) Cluster Complex: Synthesis and Structural Characterization of [Cu12Nd6(OH)24(betaine)16(NO3)3(H2O)10](NO3)[PF6]14·5H2O
Authors: Yang Yang‐Yi , Huang Zhong‐Qi , He Feng , Chen Xiao‐Ming , Ng Seik Weng 
Published: January 2004

AbstractThe new octadecanuclear Cu‐Ln complex, [Cu12Nd6(OH)24(betaine)16(NO3)3(H2O)10](NO3)[PF6]14·5H2O, was synthesized, which crystallizes in triclinic P1¯ space group, a = 18.649(6)Å, b = 20.363(7)Å, c = 19.865(7)Å, α = 116.61(2)°, β = 91.99(2)°, γ = 117.93(2)°, V = 5666(3)Å3. Its crystal structure features a [Cu12Nd6(OH)24(betaine)16(NO3)3(H2O)10]15+ core of pseudocubic Oh symmetry, with the six Nd ions positioned at the vertices of a regular octahedron and the twelve Cu ions located at the midpoints of the twelve octahedral edges. The Cu‐Nd metal framework may be viewed as a cuboctahedron, which is interconnected by twenty‐four μ3‐OH bridges that are each linked to one Nd ion and two Cu ions. In the centre of metal polyhedron, there is an encapsulated NO3— anion that exhibits a multi‐ coordinating mode.
Synthesis and Structure of a Three‐dimensional Organically Templated Zinc Ethylenediphosphonate, [NH3(CH2)2NH3][Zn3{O3P(CH2)2}4]
Authors: Natarajan Srinivasan 
Published: January 2004

AbstractA hydrothermal reaction of a mixture of ZnO, HCl, ethylenediphosphonic acid, ethylenediamine, acetic acid in a water, THF mixture gave rise to a new three‐dimensional zinc ethylenediphosphonate, [NH3(CH2)2NH3][Zn3{O3P(CH2)2}4], I. The structure, determined by single crystal X‐ray diffraction, (monoclinic, space group = C2/c, a = 16.9948(14), b = 6.7383(6), c = 16.8886(14)Å, β = 1113.568(1)°, V = 1772.7(3)Å3, Z = 4, R1 = 0.0227, wR2 = 0.0601), consists of a network of strictly alternating ZnO4 and PO3C tetrahedral units linked through their vertices forming the three‐dimensional structure. The amine molecules occupy the middle of the 8‐membered channels and interact with the framework through the hydrogen bonds. Unlike other zinc diphosphonates, I appear to have close similarity to zinc phosphate structures reported in the literature. To our knowledge, this is the first three‐dimensional zinc diphosphonate prepared in the presence of an organic amine molecule.
Magnetic Investigations and 151Eu Mössbauer Spectroscopy of MYbSi4N7 with M = Sr, Ba, Eu
Authors: Höppe Henning A. , Trill Henning , Kotzyba Gunter , Mosel Bernd D. , Pöttgen Rainer , Schnick Wolfgang 
Published: January 2004

AbstractThe isotypic nitridosilicates MYb[Si4N7] (M = Sr, Ba, Eu) were obtained by the reaction of the respective metals with Si(NH)2 in a radiofrequency furnace below 1600 °C. On the basis of powder diffraction data of MYb[Si4N7] Rietveld refinements of the lattice constants were performed; these confirmed the previously published single‐crystal data. The compounds contain a condensed network of corner‐sharing [N(SiN3)4] units. The central nitrogen thus exhibits ammonium character. Magnetic susceptibility measurements of MYb[Si4N7] (M = Sr, Ba, Eu) show paramagnetic behavior with experimental magnetic moments of 3.03(2), (Sr), 2.73(2) (Ba), and 9.17(2) (Eu) μB per formula unit. In EuYbSi4N7 the europium and ytterbium atoms are in stable divalent and trivalent states, respectively. According to the non‐magnetic character of the alkaline earth cations, ytterbium has to be in an intermediate valence state YbIII‐x in the strontium and barium compound. Consequently, either a partial exchange N3—/O2— resulting in compositions MYbIII‐x[Si4N7—xOx] or an introduction of anion defects according to MYbIII‐x[Si4N7—x/3□x/3] has to be assumed. The phase width 0 ≤ x ≤ 0.4 was estimated according to the magnetic measurements. 151Eu Mössbauer spectra of EuYb[Si4N7] at 78 K show a single signal at an isomer shift of δ = —12.83(3) mm s—1 subject to quadrupole splitting of ΔEQ = 5.7(8) mm s—1, compatible with purely divalent europium.
Neue heterometallische Organoderivate von Haupt‐ und Nebengruppenelementen mit dem 2‐(Dimethylaminomethyl)ferrocenyl(1‐)‐Liganden FcN(1‐) und der N‐[2‐N′, N′‐(Dimethyl‐aminoethyl)‐N‐methyl‐aminoethyl]ferrocenyl(1‐)‐Gruppierung FcN, N(1‐)
Authors: Jacob Klaus 
Published: January 2004

AbstractNeuartige — vorzugsweise seit 1998 beschriebene — heterometallische Organoderivate von Haupt‐ und Nebengruppenelementen mit dem 2‐(Dimethylaminomethyl)ferrocenyl(1‐)‐Liganden FcN(1‐) und dem N‐[2‐N′, N′‐(Dimethylaminoethyl)‐N‐methyl‐aminoethyl]ferrocenyl(1‐)‐ Rest FcN(1‐) als Organogruppen werden zusammenfassend vorgestellt. Es wird ein Überblick verwendeter Synthesemethoden und vorliegender Molekülstrukturen gegeben.
Zur Kenntnis der inversen Perowskite M3TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb)
Authors: Velden A. , Jansen M. 
Published: January 2004

AbstractCa3SiO und sieben weitere inverse Perowskite M3TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb) wurden durch die Reaktion 6 M + TO2 + T = 2 M3TO bzw. 3 M + TO = M3TO für Yb3PbO in verschlossenen Reineisentiegeln unter Argon bei Temperaturen von 1123—1173 K dargestellt. Die Kristallstrukturen aller Verbindungen wurden mit Röntgenpulvermethoden bestimmt und verfeinert. Ca3SiO, Ca3GeO, Sr3SiO, Sr3GeO sowie Yb3SiO und Yb3GeO sind orthorhombische Perowskite (anti‐GdFeO3‐Typ, Raumgruppe Pbnm, Nr. 62, Z = 4). Sie sind aus schwach verzerrten, eckenverknüpften OM6‐Oktaedern aufgebaut, die bezüglich ihrer Lagen in der idealen inversen Perowskit‐Struktur gekippt sind. Der Wirkungsradius von T4— variiert signifikant mit der Art der M2+, weshalb diese Verbindungen außerhalb des Geltungsbereichs des “hard‐sphere” Modells liegen und der Goldschmidt'sche Toleranzfaktor als strukturchemisches Kriterium nicht mehr greift. Die ideal‐kubischen Verbindungen Yb3SnO und Yb3PbO wurden in der Raumgruppe Pm3¯m verfeinert (anti‐SrTiO3‐Typ, Z = 1).
Caesium Heptaiodo‐Dititanate(III), CsTi2I7
Authors: Jongen Liesbet , Meyer Gerd 
Published: January 2004

AbstractCaesium heptaiodo‐dititanate(III), CsTi2I7, is obtained from CsI, Ti and TiI4 at 250 °C in a sealed tantalum ampoule as dark red single crystals. The crystal structure (trigonal, R‐3, a = 1706.6(3), c = 2088.3(5) pm, Z = 12, R1 = 0.0619) contains [TiI4] tetrahedra sharing common vertices (with Ti—I—Ti angles of 180°) to isolated ditetrahedra [Ti2I7]—. It may also be described as a cubic closest packing of alternating CsI3 and I4 layers between which neighbouring tetrahedra are occupied in a way that [Ti2I7]— ditetrahedra are achieved.http://www.gerdmeyer.de
New Phases in the Lithiumnitridovanadate System — The Solid Solution Li7‐2xMgx[VN4] with 0 ≤ x ≤ 1
Authors: Niewa Rainer , Zherebtsov Dmitry A. 
Published: January 2004

AbstractSolid solution phases Li7‐2xMgx[VN4] (0 < x ≤ 1) with varying Mg‐content are obtained as yellow microcrystalline powders from heat treatment of mixtures of VN, Li3N and Mg3N2 or from mixtures of Li7[VN4] and Mg3N2 at 1370 K in N2 atmosphere at ambient pressure. At substitution parameter values of x > 0.5 a subsequent distortion from the ideal cubic unit cell to an orthorhombic unit cell is observed. The crystal structure of Li7‐2xMgx[VN4] with x ≈ 1 was refined from neutron and X‐ray powder diffraction data (space group Pbca, No. 61, a = 963.03(3) pm, b = 958.44(3) pm, c = 951.93(2) pm, neutron pattern 14° — 156° 2θ, step non‐linear ≈ 0.0782° 2θ, No. of measured points 1816, Rp = 0.089, Rwp = 0.115, RBragg = 0.155, RF = 0.114; X‐ray pattern 10° — 98° 2θ, step 0.005° 2θ, No. of measured points 17600, Rp = 0.028, Rwp = 0.045, RBragg = 0.113, RF = 0.133, structure variables: 45). The crystal structure resembles a Li2O type superstructure with the atomic arrangement of β‐Li7[VN4] and with two crystallographic Li‐sites each substituted by Mg with statistical occupation factors of 0.5. Chemical analyses prove the composition and XAS spectroscopy at the V K‐edge support the +5 oxidation state assignment for vanadium. XAS data also support the tetrahedral coordination of vanadium by N as indicated by the structure refinements.