bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intensity and distribution of background x‐rays in wavelength‐dispersive spectrometry
Authors: Arai Tomoya 
Published: May 2005

AbstractExtensive studies of the components and distribution which govern background x‐ray intensity in the short wavelength region of wavelength‐dispersive spectrometry have been made. The theoretical calculations account for the contribution of coherent scattering (including anomalous dispersion factors), Compton scattering and absorption effects. For the precise comparison between the calculated and experimentally measured intensities, coherent and Compton scattered intensities of Rh Kα and Rh Kβ emitted from a rhodium‐target x‐ray tube were investigated with respect to different kinds of specimens. From the differences in the calculated and measured intensities, the intensity tailing of the large peak of the major components was found to be the Compton scattering of fluorescent x‐rays. A theoretical expression for calculating the magnitude of the background x‐ray intensity using an appropriately selected standard sample is described. The application of Co Kα x‐rays interferred by Fe Kβ x‐rays and the small intensity change in background x‐rays for the trace element analysis of steel samples are discussed.
A standardless ZAF correction for semi‐quantitative electron probe microanalysis of microscopical particles
Authors: Van Borm W. A. , Adams F. C. 
Published: May 2005

AbstractA procedure for automaied microanalysis is adapted from a correction procedure for bulk samples. A particle size correction, based on the projected diameter of the particle, assumed to be spherical, is implemented when the diameter is less than or equal to the electron interaction diameter. A bulk correction is applied in the opposite case. The method is applicable to K‐ and L‐lines for the elements Na to Bi. The method is implemented in a FORTRAN computer program QUANTA written for personal computers. The procedure offers interactive control of several parameters of a single ZAF correction as it is capable of processing the massive amount of data produced by automated analysis of large particle collections. The method uses literature data on a number of fundamental parameters and performs the ZAF corrections by making a compromise between calculation speed and accuracy using first‐order corrections for backscattering, absorption and secondary fluorescence effects. It was tested on a set of alloy standards, mineral standards and mineral particle standards.
IUPAC—nomenclature system for x‐ray spectroscopy
Authors: Jenkins R. , Manne R. , Robin R. , Senemaud C. 
Published: May 2005

AbstractThis report is one of a series on the nomenclature for spectrochemical analysis issued by the International Union of Pure and Applied Chemistry. It concerns a new notation for X‐ray emission lines and absorption edges, to be called IUPAC Notation, which replaces the existing Siegbahn notation. It is based upon the energy level designation and has the advantage of being simple and easy to apply to any kind of transition. Moreover, it is consistent with the notations used in electron spectroscopy.The document first discusses the terms currently used in X‐ray spectroscopy and then describes the principles of the IUPAC notation with reference to the X‐ray levels and the X‐ray transitions. The correspondence between Siegbahn and IUPAC notations for all X‐ray lines is given in a table. Finally, the document gives the units and conversion factors used in the X‐ray range.
X‐ray fluorescence analysis of tree rings
Authors: Gilfrich J. V. , Gilfrich N. L. , Skelton E. F. , Kirkland J. P. , Qadri S. B. , Nagel D. J. 
Published: May 2005

AbstractX‐ray fluorescence analysis was applied to the determination of the concentration of trace elements in the growth rings of trees. Some of these mineral elements can affect the growth and development of the plant. The results of the analytical measurements can provide information concerning the geochemical and atmospheric environment to which the tree has been exposed. It has been demonstrated that conventional x‐ray fluorescence equipment is adequate to perform such measurements but, more important, the high intensity available from synchrotron radiation is an ideal source to probe the spatial variation in the low‐level concentrations which can be transposed to an absolute temporal scale knowing the history of the tree. The ability to aperture or focus the synchrotron radiation to submillimeter size allows several points within individual rings to be analyzed, permitting a study of differences within a single growing season.Concentrations of mineral elements were determined in two types of tree samples, a cross‐section of the trunk of a small sassafras tree and an incremental core from a red oak. Two experimental arrangements were employed, a special energy‐dispersive x‐ray analyzer with a primary beam size of 0.5 mm and a beam line at the National Synchrotron Light Source where the radiation was focused and apertured to 50 μm × 1 mm. Concentrations as low as 1 ppm were determined for nine elements. Major year‐to‐year variations were observed, implying that cross‐ring elemental migration is slow (possibly negligible). The x‐ray technique is fast and non‐destructive, permitting the sample to be retained for additional studies.
Comparison of highly oriented pyrolytic and ordinary graphite as polarizers of Mo Kα radiation in EDXRF
Authors: Kanngiesser Birgit , Beckhoff Burkhard , Swoboda Walter 
Published: May 2005

AbstractHighly oriented pyrolytic graphite (HOPG) and ordinary graphite were compared with respect to detection limits as excitation targets in a triaxial EDXRF set‐up. HOPG as a Bragg polarizer of Mo Kα x‐rays did not show appreciable advantages over ordinary graphite as a Barkla scatterer. Under relatively wide collimation conditions necessary to obtain a sufficient count rate in analytical practice, HOPG acts mainly as a Barkla scatterer.
A peak‐to‐background method for electron‐probe x‐ray microanalysis applied to individual small particles
Authors: Lábár János L. , Török Szabina 
Published: May 2005

AbstractA peak‐to‐background (P/B) method was implemented for standardless analysis of bulk samples. Components of the model were selected from the literature on the basis of comparison with the present experimental results. Pouchou and Pichoir's characteristic x‐ray intensity calculations combined with Small et al. bremsstrahlung model proved to be the most successful in this respect. An empirical modification seems to be necessary to improve the agreement between calculated and measured P/Bs for the Lα lines of single‐element samples. For modelling the dependence of the measured P/B on the particle size, small particles are approximated as thin layers. Preliminary experimental results illustrate that even such a rough approximation works.
Determination of impurities in nuclear‐grade uranium compounds by x‐ray fluorescence spectrometry
Authors: Al‐ammar Assa d. S. , Ali F. H. 
Published: May 2005

AbstractA method in described for the simultaneous determination of trace concentrations of Ca, Cr, Cu, Fe, Mn, Ni, Mo, As, Zn, Co, Th, V and Ti in nuclear‐grade uranium oxides or other uranium compounds by x‐ray fluorescence spectrometry without the use of chemical treatment. The limits of detection are Mo 25, As 40, Cu 5, Ni 29, Co 17, Fe 5, Mn 30, Cr 8, Th 7, Zn 5, V 52, Ti 10 and Ca 80 ppm. Samples are prepared in the form of double‐layer pellets with starch as a binding agent. Standards are prepared in a U3O8 matrix, which is more chemically stable than other uranium oxides. The dynamic ranges of the calibration graphs are very large because, for all impurity elements, they are linear over three orders of magnitude of concentration. The method is fast, since it requires no chemical treatment and only limited manipulations. The method has good precision for the impurity elements.
Energy‐dispersive W Kα1 spectrometer for trace element analysis of rare‐earth elements
Authors: Manninen S. , Karhumaa R. 
Published: May 2005

AbstractA spectrometer based on the use of monochromatic W Kα1 radiation for trace element studies of rare earth elements up to Z = 68 is described. Examples including both liquid and solid samples are included. Special attention is given to the contributions arising from Compton scattering and multiple scattering in the sample matrix. The results are compared with those obtained using a 241 Am γ‐source.
Measurements of L1, Lα, Lβ and Lγ x‐ray fluorescence cross‐sections in heavy elements excited by 36.62, 43.69, 48.30, 50.20 and 53.50 keV photons
Authors: Rao D. V. , Cesareo R. , Gigante G. E. 
Published: May 2005

AbstractL1, Lα, Lβ and Lγ x‐ray fluorescence cross‐sections were measured in Au and Pb at excitation energies of 36.62, 43.69, 48.30, 50.20 and 53.50 keV. Measurements were made using an x‐ray tube with a secondary exciter system as the excitation source. The x‐ray tube with a secondary target arrangement was used to obtain high intensity with a high degree of monochromatization. By using an x‐ray tube it is possible to measure L x‐ray fluorescence cross‐sections even for low‐intensity x‐rays (L1). The experimental results were compared with the theoretically calculated values of L x‐ray fluorescence cross‐sections and a fairly good correspondence was observed.
Chemical characterization of environmental particulate matter using synchrotron radiation
Authors: Török Sz. , Faigel Gy. , Jones K. W. , Rivers M. L. , Sutton S. R. , Bajt S. 
Published: May 2005

AbstractFirst results from a new program for chemical characterization of environmental particulates using synchrotron radiation are described. Trace element concentrations and chemical state determinations were made on fly ash samples from lignite‐fired power stations. The experiments were based on the use of x‐rays produced by an electron beam passing a bending magnet at the Brookhaven National Synchrotron Light Source. The high brilliance, energy tunability and almost complete polarization of the x‐rays were used as the basis of a versatile X‐ray microscope (XRM) at the X26 beam line. Mössbauer spectroscopy was employed as a complementary method for determination of the compounds in the iron‐containing fly ash particles. The results demonstrate the practicality and strengths of using the synchrotron XRM for measurements of trace elements in fly ash particles and for the determination of oxidation states using x‐ray absorption near‐edge structure.
Analytical electron microscopy of thin segregated layers
Authors: Faulkner R. G. , Morgan T. S. , Little E. A. 
Published: May 2005

AbstractAnalytical convolution methods used to explain the interaction of a fine electron beam with a thin segregated layer in a typical electron microscope specimen are described. Expressions are derived which quantify the shape of the measured concentration profile determined in the microscope by scanning the beam across the segregated layer. The expression contains parameters concerned with the beam profile and the thickness of the segregated layer. The method is applied to grain boundary segregation studies of neutron‐irradiated ferritic‐martensitic steels.
Measuring system for obtaining concentration profiles in supported catalysts using electron‐probe microanalysis. Influence of standards
Authors: Viturro H. , Bonetto R. D. , Pizzio L. R. , Vázquez P. G. , Sanchez M. , Alvarez A. G. 
Published: May 2005

AbstractA system based on the EDAX 9100 analyser was developed to obtain concentration profiles. Even though the system can be used on any type of flat specimens, in this study it was used for measuring the tungsten (W) concentration on rough spherical specimens of the W–γ‐Al2O3 supported catalyst. The concentration gradient of the active component from the periphery to the centre of the particle is often an important factor in determining catalyst performance. The purpose was to determine the concentration profile of W along the radius of a sphere with a large enough number of experimental points to draw accurate information in a short time. In this way, a considerable number of impregnated spheres can be analysed, and average results can be calculated and taken as representative values of the population under study. The method developed provides highly satisfactory results, making it very useful for the systematic study of this type of specimen. Obviously, the use of this system can be extended to metallurgical and mineralogical specimens.
Coherent and incoherent scattering of 42.75 and 47.24 keV x‐ray photons scattered from Al, Cu, Y, Mo, Au and Pb
Authors: Rao D. V. , Gigante G. E. , Cesareo R. 
Published: May 2005

AbstractUsing nearly monoenergetic unpolarized Kα x‐ray photons, measurements were made of the coherent and Compton scattered intensity in the atomic region 13 ⩽ Z ⩽ 82 at an angle of 90° with a high‐resolution Si(Li) detection system. In order to improve the efficiency of the detection system, the excitation source, detector and the sample assembly were placed in a vacuum chamber and a pressure of 10−2 mbar was maintained throughout the measurements. Experimental scattering cross‐sections are compared with the normalized integrated cross‐sections based on form factor and incoherent scattering functions. Experimental coherent scattering cross‐sections are higher than the theoretical values, indicating the resonance behaviour, fine structure effects and oscillation of coherent intensity around the absorption edges. Experimental incoherent scattering cross‐sections are lower than the theoretical estimates for heavy elements, indicating the effect of electron binding at low photon energies.
Analysis of DNA double strand breakage and repair using orthogonal field alternation gel electrophoresis
Authors: Contopoulou C. Rebecca , Cook Vincent E. , Mortimer Robert K. 
Published: May 2005

AbstractOrthogonal field alternation gel electrophoresis (OFAGE) allows separation of DNA molecules in the size range of 200 kb to 3000 kb. These sizes encompass the chromosome sizes of the genome ofSaccharomyces cerevisiae. Using this technique, we have found that yeast cells exposed to X‐rays generate a smear of DNA fragments corresponding to the products of random, independent double strand breaks, and that the bands corresponding to unbroken chromosomes decrease in intensity in direct proportion to chromosome size. If exposed wild type cells are permitted time to repair (5 h at 30°C on YEPD), the fragments partially disappear and the chromosome bands reappear, although at less than normal intensity. In certain radiation‐sensitive mutants (rad51,rad52andrad54), the fragment smear appears following X‐ray exposure but no repair of broken chromosomes occurs. In fact, loss of the fragments occurs; this could appear as partial repair using other procedures.
Nucleotide phosphotransferase, nucleotide kinase and inorganic pyrophosphatase activities of killer virions of yeast
Authors: Georgopoulos Denise E. , Leibowitz Michael J. 
Published: May 2005

AbstractThe intracellular killer virions of yeast co‐purify with an RNA polymerase activity which catalyzes the synthesis of fulllength transcripts of the two viral genomic double‐stranded RNA segments. This polymerase utilizes ribonucleoside diphosphates or triphosphates as substrates. The virions have other associated nucleotide‐metabolizing enzyme activities, including nucleoside diphosphate kinase, adenosine monophosphate kinase, and nucleoside triphosphate phosphotransferase, an activity which catalyzes the exchange of gamma‐phosphate from any ribonucleoside triphosphate with any ribonucleoside or deoxyribonucleoside triphosphate. The purified virions also contain an inorganic pyrophosphatase activity. These enzymes may allow the virus to utilize nucleotide pools distinct from those utilized in host cell transcription.
Ethanol and the fluidity of the yeast plasma membrane
Authors: Jones Rodney P. , Greenfield Paul F. 
Published: May 2005

AbstractEvidence is presented for an exponential increase in yeast plasma membrane fluidity (as meaured by pasive permeability to acetic acid) with ethanol concentration. The role of adaptation of yeast cells to ethanol can be seen in the existence of a threshold concnetration before the onset of an observed fluidizing effect. The physiological state of the yeast cells is also demonstrated to influence the sensitivity of the membrane to fluidizatio by ethanol. On the basis of these results, the concept that increased fluidity is an adaptive response conferring ethanol tolerance is disputed. An alternative hypothesis, namely that the observed increase in fluidity is the net result of a number of more fundamental changes, is presented to explain the observed effects.
Genetic analysis of the gene ICL1 of the yeast Yarrowia lipolytica
Authors: Barth Gerold , Weber Herbert 
Published: May 2005

AbstractThe gene ICL1 codes for the tetrameric enzyme isocitrate lyase of Y. lipolytica. Twenty icl1− alleles have been analysed for their reversion frequency, their interallelic complementation pattern, and the position of the corresponding mutation site on the fine structure map of the gene ICL1. One intragenic temperature‐sensitive revertant of the allele icl1D‐39 was isolated, which expressed a thermolabile enzyme. In spite of the fact that no nonsense mutations have been detected, the direction of transcription of the gene ICL1 was inferred from the localization of a linked cis‐dominant regulatory mutation site. The size of the mitotic map of this gene suggests that recombination frequency in Y. lipolytica is lower than in Saccharomyces cerevisiae.
Pleiotropic mutations in Saccharomyces cerevisiae affecting sterol uptake and metabolism
Authors: Lewis T. L. , Keesler G. A. , Fenner G. P. , Parks L. W. 
Published: May 2005

AbstractSterol uptake control mutants (upc−) have been isolated via ethylmethanesulfonate mutagenesis from wild‐type Saccharomyces cerevisiae. These mutants are heme and sterol competent but possess the ability to accumulate exogenous sterol(s) under aerobic conditions. Previous demonstrate sterol uptake only in a hem−, erg− background; however, the Upc− strains described here are Hem+ and do not require exogenous sterol for growth. We were unable to obtain viable hem+, erg−, upc+ recombinants; such combinations appear to be lethal. Isolates of Upc mutants demonstrated different levels of sterol uptake, and sterol analysis revealed a broad phenotypic range with regard to amounts and accumulation of ergosterol and non‐ergosterol sterols. Assays of acyl CoA: ergosterol acyltransferase and sterol ester hydrolase showed no apparent difference in activity between Upc mutants and the wild type.
Purification and properties of dihydroxyacetone reductase and 2,3‐butanediol dehydrogenase from Candida utilis CBS 621
Authors: Verduyn Cornelis , Breedveld Guido J. , Scheffers W. Alexander , Van Dijken Johannes P. 
Published: May 2005

AbstractCandida utilis CBS 621 contained four different enzymes capable of reducing carbonyl compounds such as dihydroxyacetone, acetoin, diacetyl, acetol, methylglyoxal and acetone, namely alcohol dehydrogenase, acetone reductase, dihydroxyacetone reductase and 2,3‐butanediol dehydrogenase. The dihydroxyacetone reductase of C. utilis did not oxidize glycerol, thus providing evidence that this enzyme cannot function as a glycerol‐2‐dehydrogenase during growth of the yeast on glycerol. This enzyme may, however, play a role in the assimilation of 2,3‐butanediol by C. utilis. The organism also contained a separate 2,3‐butanediol dehydrogenase which was unable to reduce dihydroxyacetone. Both dihydroxyacetone reductase and 2,3‐butanediol dehydrogenase were present at very high activities during growth of C. utilis on a variety of substrates, including 2,3‐butanediol.
Analysis of chromosomal DNA patterns of the genus Kluyveromyces
Authors: Sor Frédéric , Fukuhara Hiroshi 
Published: May 2005

AbstractUsing an improved procedure of pulsed field gel electrophoresis, yeast chromosomes were separated over a wide range of molecular size (250–4000 kbp) on single gels. The chromosomal DNA patterns of all the species belonging to the genus Kluyveromyces were examined. Within the species K. marxianus, the varieties lactis, drosophilarum and vanudenii showed closely related patterns; very different from them, the varieties bulgaricus and marxianus were related to each other, forming a distinct group; the strains commonly called ‘K. lactis’ and ‘K. fragilis’ were unambiguously different from each other in chromosome patterns. These differences were correlated with the presence of characteristic repetitive sequence elements in the mitochondrial DNA of the former group and not in the latter. Analysis of Candida macedoniensis, which had been considered to be an anamorph of K. marxianus var. marxianus, showed that these two yeast species were indeed similar in chromosome patterns and in mitochondrial DNA restriction patterns.
Cloning and analysis of the Kluyveromyces lactis TRP1 gene: A chromosomal locus flanked by genes encoding inorganic pyrophosphatase and histone H3
Authors: Stark Michael J. R. , Milner Jonathan S. 
Published: May 2005

AbstractThe TRP1 gene of the yeast Kluyveromyces lactis has been cloned from a genomic library by complementation of the Saccharomyces cerevisiae trpl‐289 mutation. The gene was located within the clone by transposon mutagenesis and the coding region identified by DNA sequencing. This has indicated that K. lactis TRP1 encodes a 210‐amino acid polypeptide which shows 53% identity to the homologous S. cerevisiae protein. The K. lactis TRP1 gene has been disrupted by substituting the S. cerevisiae URA3 gene for a large part of the TRP1 coding sequence. Replacement of the chromosomal TRP1 locus with this construction has enabled the production of non‐reverting trp1− strains of K. lactis, while a genetic analysis of the disrupted allele confirmed that the TRP1 gene had been cloned. DNA sequencing has also shown that the K. lactis TRP1 sequences is flanked by genes encoding inorganic pyrophosphatase and histone H3, which we have designated IPP and HHT1 respectively. Hybridization studies have shown that in common with S. cerevisiae, K. lactis has two copies of the histone H3 gene. Each H3 gene is closely linked to a gene encoding histone H4 and in both yeast species the IPP gene is tightly linked to one of the histone gene pairs.
RAG1 and RAG2: Nuclear genes involved in the dependence/independence on mitochondrial respiratory function for growth on sugars
Authors: Goffrini P. , Algeri A. A. , Donnini C. , Wesolowski‐Louvel M. , Ferrero I. 
Published: May 2005

AbstractThe analysis of five independent isolates of Kluyveromyces lactis shows that CBS 2359, CBS 683 and CBS 4574 could grow in the presence of mitochondrial inhibitors (antimycin A, oligomycin or erythromycin) and that CBS 2360 and CBS 141 were unable to grow in the presence of drugs. The resistant growth was observed only on glucose and not on other fermentable carbon sources (galactose, lactose).The phenotype ‘growth on glucose in the presence of mitochondrial inhibitors’ was called Rag+. This phenotype was found to be controlled by two unlinked nuclear genes: RAG1 and RAG2. Either of their recessive alleles, rag1 and rag2, led to the Rag− phenotype (i.e. the failure of growth on glucose in the presence of antimitochondrial drugs).Rag− strains represent the case in which fermentative growth becomes absolutely dependent on the functioning of the normal respiratory chain.