bluuebunny/crossref_metadata_2025_split huggingface dataset:
Si(Li) detector efficiency in standard X‐ray fluorescence geometries
Authors: Szöghy I. M. , Simon J. , Kish L. 
Published: May 2005

AbstractSi(Li) detector efficieneres are measured up to 100 keV photon energy in typical X‐ray fluorescence geometries using 55Fe, 109Cd, 57Co and 241Am annular sources. The targets are common chemical compounds. The photopeak yield is normalized by the use of a bare CaF2(Eu) scintillator which is free of dead layer. The scintillator response is corrected for escape peak losses. The presented method permits the detection of long term changes in detector response. Discrepancies are found in published nominal detector thicknesses.
The complete spectral response for EDXRF systems—calculation by Monte Carlo and analysis applications. 1—homogeneous samples
Authors: Doster Joseph M. , Gardner Robin P. 
Published: May 2005

AbstractA Monte Carlo model is derived and combined with an existing detector response function model to ptdict the entire pulse‐height spectra for energy‐dispersive, x‐ray fluorescence systems that consist of an annular‐ring, photon exciting source, a coaxially positioned right circular homogental sample, and a cirular si(Li) detector. A method is dervied and demonstrated for using the predicted and experimental pulse‐height spectra on a chi‐square basis to determine elemental amounts. This approach allows the use of all the information available in an entire energy‐dispersive, x‐ray fluorescence pulse‐hight spectrum for analysis purposes.
X‐ray production in thin films by electrons with energies between 40 and 100 keV. 1—Bremsstrahlung cross‐sections
Authors: Chapman J. N. , Gray C. C. , Robertson B. W. , Nicholson W. A. P. 
Published: May 2005

AbstractCross‐sections for bremsstrahlung production in thin films may be derived theoretically only if certain approximations are made or if there is recourse to numerical techniques. In this paper, two approximate equations, one based on the Sommerfeld theory and the other on the Bethe–Heitler theory, are assessed for their accuracy in predicting cross‐sections differential in photon energy and emergence angle when a thin foil target is bombarded with electrons with energies between 40 and 100 keV. Experimental data are presented from eight different target materials and these are processed initially to make comparisons between experimental and theoretical spectral shapes and subsequently to compare observed and predicted absolute cross‐section values. Except for the heaviest target material (Au), the Bethe–Heitler theory provided a satisfactory description of all experimental observations. In contrast, the Sommerfeld theory provided a significantly inferior description of spectral shapes and consistently overestimated absolute cross‐sections by 15–20%.
Routineverfahren zur serienanalytik geologischen materials mittels XRFS
Authors: Müller N. 
Published: May 2005

AbstractIm Rahmen des österreichischen Rohstoff‐Forschungsprojektes Geochemische Basisuntersuchung von Bach‐ und Flußsedimenten wurden mehr als 25 000 Proben einer Multielementanalytik auf 36 Elemente unterzogen. Neben optischer Spektroskopie mit Kohlebogen‐ und induktiv gekoppelter Plasmaanregung gelgangten wellenlangen‐ und energie‐dispersive XRFS zum Einsatz. Es wird ein Verfahren beschrieben, das
es ermoglicht, die Analyse der Fraktion mit einem Korndurchmesser <0.18 mm auf bis zu 30 Elemente rnit hoher Genauigkeit bei einer breiten Streuung des Matrixbereiches durchzufiihren. Der Grundgedanke dabei ist, eine große Zahl von gut analysierten Referenzproben verschiedenster Zusammensetzung fiir die Eichung heranzuziehen.
X‐ray K absorption edges of cobalt and copper in their tetraphenylporphyrin (TPP) and formate di‐ and tetrahydrate (FDH) (FTH) compounds
Authors: Rajput O. P. , Nigam A. N. , Shrivastava B. D. 
Published: May 2005

AbstractK absorption edge data for TPP and FDH compounds of cobalt and copper have been recorded. Edge position shifts, changes in edge widths and shifts in the position of first absorption maximum are discussed.
EXAFS studies of some copper and cobalt compounds and complexes in aqueous solution and polycrystalline form
Authors: Koul P. N. , Padalia B. D. 
Published: May 2005

AbstractExtended x‐ray absorption fine structures (EXAFS) associated with K‐absorption edges of copper and cobalt in their simple compounds and trisethylenediamine complexes both in aqueous solution and in the polycrystalline form have been measured. Bond lengths in these samples have been determined. An attempt is made to give a qualitative explanation for the appearance of some EXAFS peaks in solution that do not occur with the polycrystalline form of the same sample.
The operator model for X‐ray fluorescence and its application to inter‐element effect corrections in XRF analysis
Authors: Werfel Zbigniew W. 
Published: May 2005

AbstractA new empirical mathematical method for inter‐element effect corrections in XRF analysis is presented. It is based on a special theoretical description of XRF phenomena called OMX (operator model of x‐ray fluorescence), presuming a discrete layer model of the sample structure and using mathematical operators to describe the interaction between sample layers and exciting radiation. The operators formed generally as spectral distributions may be simplified into the matrix form for practical application. The effectiveness of the proposed method was verified experimentally by analysing samples of glass and glass raw materials.
Chemical effects in X‐ray fluorescence analysis
Authors: Kataria S. K. , Govil R. , Saxena A. , Bajpei H. N. 
Published: May 2005

AbstractEnergy‐dispersive x‐ray fluorescence (EDXRF) analysis of manganese compounds has been carried out. A significant dependence of the Mn Kα and Kβ x‐ray yields per incident photon and of the Kβ/Kα ratio on the valence state of manganese in these compounds was observed. The measurement of attenuation coefficients of these compounds, which are used in absorption corrections in XRF analysis, also showed similar effects. These results imply that the EDXRF elemental analysis results have inherent inaccuracies of the order of 10%.
Evaluation of correction algorithms with theoretically calculated influence coefficients in wavelength dispersive XRF
Authors: Vrebos B. A. R. , Helsen J. A. 
Published: May 2005

AbstractThree correction algorithms for quantitative XRF analysis of samples of infinite thickness have been compared using intensities and influence coefficients calculated from fundamental parameters. Errors due to heterogeneity and counting errors are avoided by this procedure. Both the three‐coefficient model of Lachance and the α‐model of de Jongh proved to be very satisfactory. The choice has to be made depending on the computer facilities available.
Mathematical matrix correction procedures for x‐ray fluorescence analysis. A critical survey
Authors: Tertian R. 
Published: May 2005

AbstractThe complexity of the intensity–concentration relationship in x‐ray fluorescence analysis as well as new requirements for speed and accuracy will induce analysts to resort more and more to mathematical methods for effecting matrix correction. A thorough study of Lachance–Traill coefficients, based on theoretically calculated fluorescence intensities, shows that all ‘binary’ coefficients vary systematically with composition under the usual working conditions with polychromatic excitation, while ‘multicomponent’ coefficients can no longer be represented (i.e. in the form of curves or diagrams) owing to the intricacy of third element effects. For these reasons, we are compelled to turn to a fundamental approach, where two methods are now competing: on the one hand, the classical fundamental parameter method, which permitted the abovementioned investigation, but does not in itself offer a sufficiently coherent solution to the problem of matrix correction; on the other, the new fundamental coefficient method, which accounts for all theoretical implications, but preserves the flexibility and adaptability of the older influence coefficient procedures. Utilizing such effective coefficients in a comparison standard correction algorithm allows one to solve any analytical problem, from the most complicated to the simpler ones, through a kind of ‘à la carte’ procedure. The so‐called empirical algorithms are in principle ineffective for treating the complex corrections which belong to the analysis of compact specimens (e.g. metal alloys). They must be reserved for simpler problems, notably the study of diluted specimens where an experimental calibration remains feasible.
Measurement of the dead time of XRF detection systems using a pulsed beam
Authors: Méray L. 
Published: May 2005

AbstractA method of measuring the dead time of nuclear detectors using a pulsed beam is described. The application of the method to detectors used in an electron microprobe device is reported and results obtained in this way are presented. The method seems to be suitable for measuring the dead time of any nuclear x‐ray counting system which can be operated with a pulsed beam.
XANES study of tungsten LIII discontinuity in some rare earth tungstates
Authors: Vishnoi A. D. , Sapre V. B. , Mande C. 
Published: May 2005

AbstractThe shape and near edge structure of the LIII absorption discontinuity of tungsten in some rare earth tungstates, RE2(WO4)3, were studied using a 40 cm Cauchois‐type transmission x‐ray spectrograph. Molecular orbital theory was used to interpret the fine structure.
Use of the DuMond arrangement in analytical x‐ray spectrometers
Authors: Verman B. S. , Serikov I. V. 
Published: May 2005

AbstractA comparison of estimated performance of x‐ray spectrometers employing Cauchouis and DuMond arrangements shows that the latter are 5‐15 times more efficient at the same resolution. These data and the experimental performances of the above spectrometers and of the Soller type in the U Lα1 region with standard granite specimens suggest that it is advisable to develop short‐wavelength analytical spectrometers with the DuMond arrangement.
Mean depth of X‐ray production by electron beams in thick targets
Authors: Gaber M. , El‐Khier A. A. Abou 
Published: May 2005

AbstractAn analytical expression was deduced for calculating the mean depth of ionization, pz, in electron probe x‐ray microanalysis. The data used were generated from previous Monte Carlo calculations for bulk targets of aluminium, titanium, iron, copper, arsenic, indium, tungsten, gold and lead at normal electron incidence for energies ranging from 10 to 40 keV. The results show that the mean depth pz depends on the back scattering coefficient,η, the energy of the incident electron, Eo, the excitation energy of the target atoms, Ec, and the target atomic number, Z. In the case of non‐normal incidence, it is found that the ratio of the mean depth pz(α) at an angle of incidence α to the mean depth pz(0) at normal incidence varies linearly with cos α and depends only on the atomic number of the target material. The effect of the atomic number of the target on the ionization mean depth was also studied.
Calibration of analytical spectrometers and metrological aims of quantitative analysis
Authors: Kotlyarov Yakov B. 
Published: May 2005

AbstractThe mathematical criteria of calibration, which reflect the metrological aims of quantitative analysis, are formulated. It is shown that the traditionally used calibration procedure is not adequate for these criteria when using the analytical techniques which are required to solve jointly the calibration functions for concentrations in the course of the analysis. A procedure which avoids this shortcoming is proposed. It stipulates the simultaneous construction of the calibration functions and is based on the utilization of a specially introduced metrological index, the ‘indicator of the inaccuracy of a sample analysis’. The paper theory is illustrated by examples in x‐ray fluorescence analysis.
LIII subshell intensity ratios of Pb, Th and U
Authors: Tan M. , Sahin Y. , Saplakǧlu A. 
Published: May 2005

AbstractA study of LIII intensity ratios by using characteristic x‐rays as the exciting radiation is described. Only the LIII subshells of Pb, Th and U were excited by the characteristic x‐rays of the elements used as the secondary sources. A Ge(Li) detector system coupled to a programmable multi‐channel analyser was used in the measurements. Lα1, 2/L1, Lα1, 2/Lβ6 and Lα1, 2/Lβ2, 15 intensity ratios of Pb, Th and U were determined by spectral analysis and were compared with recent theoretical and experimental results.
Effect of non‐radiative transitions on the number and depth distribution of generated x‐ray photons
Authors: L. Lábár János 
Published: May 2005

AbstractNon‐radiative transitions enhance the generated Lα intensity by 20–50%. A critical assessment of the dependence of the enhancement on the type of ionizing radiation and on the experimental condition is presented. Numerical values of the enhancement are given as a function of atomic number for situations common in EPMA, TEM/EDS and XRF. It is outlined how to incorporate these effects into standardless analysis, the Cliff–Lorimer method and the fundamental parameter approach. It is shown that even conventional EPMA with measurement of standards may be affected if stratified samples are examined. Measurements and Monte Carlo simulations are suggested for testing the latter prediction.
Narrow‐beam attenuation curve as a functional description of a low‐energy x‐ray beam
Authors: Delgado V. , Ortiz P. 
Published: May 2005

AbstractIt is shown that the narrow‐beam attenuation curve can be a functional description of a low‐energy x‐ray beam, as is the spectral distribution. Physical quantities, which are usually calculated by integration over the spectral distribution (differential photon or energy fluence), can also be obtained from the narrow‐beam attenuation curve without any need for an explicit knowledge of the spectral distribution.
Validity of a simple approximation for enhancement calculations
Authors: Rössiger V. 
Published: May 2005

AbstractFor calculating secondary XRF intensities, the substitution of the isotrope emission of the enhancing radiation by an emission with a few discrete angles leads to considerably reduced numerical effort. The validity of this previously suggested approximation of the enhancement effect is discussed for the analsysis of multilayer system in the nm and μm region and for bulk materials.
Characterization of an x‐ray source for the fundamental parameter method
Authors: Pozsgai I. 
Published: May 2005

AbstractIn addition to low detection limits, x‐ray fluorescene analysis (XRF) with a transmission x‐ray source in the scanning electron microscope has other favourable features as a consequence of the microscope environment, e.g. selection of area for XRF by backscattered electron imaging or electron probe microanalysis. Another favourable feature, the ease of determining the energy distribution of the intensity of the x‐ray source, is discussed.
Simultaneous determination of rare earths by x‐ray fluorescence spectrometry using a fundamental parameters method
Authors: Marcó Parra L. M. , Greaves E. D. , Paz J. L. , Sajo‐Bohus L. 
Published: May 2005

AbstractConcentrates extracted from a lateritic mineral deposit were analysed for their rare earth (RE) content by energy‐dispersive x‐ray fluorescence (XRF) spectrometry. The L emission lines of the lanthanides were excited with the 22.1 keV Ag K radiation from an annular Cd‐109 radioisotope source. The problem of the extensive overlap of the L lines were solved by the AXIL program for deconvolution of XRF spectra. Individual REs were quantified by preparing semi‐transparent pellets of the concentrate with starch which served as dilutant and binder. This allowed correction for sample absorption with the light matrix program of the QXAS analysis package based on the fundamental parameter method. The method allowed the simultaneous determination of 12 rare earths contained in the sample, with a reproducibility of 2.0–29% and accuracy in the range 1.5–24% relative error without the use of standard materials. Detection limits achieved were in the range of 340 ppm for the heavy REs and 4000 ppm for the light REs.
Photon‐excited K x‐ray fluorescence cross‐sections for some light elements in the energy range 20–60 keV
Authors: Rao D. V. , Cesareo R. , Gigante G. E. 
Published: May 2005

AbstractKα and Kβ x‐ray fluorescence cross‐sections were experimentally determined for elements in the range 26 ⩽ Z ⩽ 40 at various excitation energies using and 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. Experimental values were compared with the theoretical values calculated using IKβ/IKα ratios based on Hartree—Fock and Hartree—Slater theories. The experimental values for all the elements at various excitation energies were in good agreement with the theoretical values.
Energy‐dispersive measurement and comparison of different spectra from diffraction x‐ray tubes
Authors: Görgl R. , Wobrauschek P. , Streli Ch. , Aiginger H. , Benedikt M. 
Published: May 2005

AbstractDirect measurement of the spectral distribution emitted by an x‐ray tube with a solid‐state detector is described. Spectral distributions of various x‐ray tubes differing in anode material were measured and compared. Numerical values and relevant data for Cu, Mo and W x‐ray tubes are presented.
Expression of the Drosophila 70 000 Dalton heat shock protein is translationally controlled in yeast
Authors: Collatz Ekkehard , Plesset Judith , Foy James J. , McLaughlin Calvin S. 
Published: May 2005

AbstractPlasmid pPW229, containing the 2·25 kilobase transcribed sequence for the 70 000 Dalton heat shock protein of Drosophila,1 was integrated into plasmid CV13 and used to transform Saccharomyces cerevisiae. Upon a heat shock, at 41°C for 20 min, a new 70 000 Dalton protein appeared in the transformants. This protein was not detected in transformants grown at 23°C, nor in transfromants carrying the hybrid plasmid from which the structural gene for the 70 000 Dalton protein had been deleted. RNA was isolated from transromants grown at 23°C and from transformants heat shocked at 41°C. RNA complementary to the Drosophila heat shock gene was present in the transformants, grown either at 23°C or heat shocked. No complementary RNA was detected in yeast cells transformed with the hybrid plasmid from which the structural gene had been deleted. The Drosophila heat shock gene in yeast appears to be transcribed constitutively but translated only under heat shock conditions.
Primary structure of the Saccharomyces cerevisiae GAL7 gene
Authors: Tajima Masahiro , Nogi Yasuhisa , Fukasawa Toshio 
Published: May 2005

AbstractWe present the nucleotide sequence of a 1599‐base pair (bp) DNA fragment containing the entire GAL7 gene that encodes galactose‐1‐phosphate uridyltransferase of Saccharomyces cerevisiae. The deduced peptide was composed of 364 amino acid residues. The expected molecular weight was 42 005 daltons, which agreed with the observed value for the purified enzyme.1 The 3′‐end of the GAL7 transcript mapped at a position 82 bp downstream from the UAA termination codon by the S1 nuclease protection experiment. We constructed a GAL7′‐lac′Z fusion on various types of yeast plasmid vectors. The fused gene on any type of vector was induced by galactose and repressed by glucose as for the GAL7 gene on the chromosome. The response of GAL7′‐lac′Z fusion to gal4Δ and gal80Δ regulatory mutations was also similar to the response of the chromosomal GAL7 gene. By using various deletions in the 5′‐flanking region of the gene fusion, we delimited the sequence essential for galactose controlled expression with a 180 bp‐fragment of DNA lying 92 bp upstream of the transcription initiation site.
Structure and nuclear localization signal of the SK13 antiviral protein of Saccharomyces cerevisiae
Authors: Rhee Sang‐Ki , Icho Tateo , Wickner Reed B. 
Published: May 2005

AbstractThe yeast chromosomal genes SK12, SK13, SK14, SK16, SK17 and SK18 repress the replication of double‐stranded RNA viruses, protecting the host from the otherwise lethal effects of the virus. We cloned and sequenced the SK13 gene and found that it encodes a 163 kDa protein including a typical nuclear localization signal. Cell fractionation experiments show that the SK13 gene product is indeed tightly associated with nuclei and that the putative nuclear localization sequence directs β‐galactosidase into the nucleus. However, fusion of a part of the SK13 protein lacking this signal with β‐galactosidase directs β‐galactosidase into the nucleus, suggesting the presence of a second nuclear localization signal. The SK13 gene is only essential in the presence of an M double‐stranded RNA virus.
Divergence and conservation of SUP2(SUP35) gene of yeasts Pichia pinus and Saccharomyces cerevisiae
Authors: Kushnirov Vitaly V. , Ter‐Avanesyan Michael D. , Didichenko Svetlana A. , Smirnov Vladimir N. , Chernoff Yuri O. , Derkach Irina L. , Novikova Olga N. , Inge‐Vechtomov Sergey G. , Neistat Michael A. , Tolstorukov Ilya I. 
Published: May 2005

AbstractSUP2(SUP35) is an omnipotent suppressor gene, coding for an EF‐1α‐like protein factor, intimately involved in the control of translational accuracy in yeast Saccharomyces cerevisiae.In the present study a SUP2 gene analogue from yeast Pichia pinus was isolated by complementation of the temperature‐sensitive sup2 mutation of S. cerevisiae.The nucleotide sequence of the SUP2 gene of P. pinus codes for a protein of 82·4 kDa, exceeding the Sup2 protein of S. cerevisiae by 6 kDa. Like the SUP2 gene product of S. cerevisiae, the Sup2 protein of P. pinus represents a fusion of a unique N‐terminal part of a region homologous to EF‐1α. The comparison of amino acid sequences of the Sup2 proteins reveals high conservations (76%) of the C‐terminal region and low conservation (36%) of the N‐terminal part where, in addition, the homologous correspondence is ambiguous.Proteins related to the Sup2 of S. cerevisiae where found in P. pinus and some other yeast species by the immunoblotting technique.The relation between the evolutionary conservation of different regions of the Sup2 protein and their functional significance is discussed.
The MAT locus revisited within a 9·8 kb fragment of chromosome III containing BUD5 and two new open reading frames
Authors: Jacquet Michel , Buhler Jean Marie , Iborra François , Francingues‐Gaillard Marie Claude , Soustelle Christine 
Published: May 2005

AbstractThis paper reports the DNA sequence of a segment of 9·8 kb of the chromosome III. The sequenced DNA contains the MATα locus. The new sequence of the MATα locus differs from the previously reported sequence by six modifications in the W segment. We have found the same modifications in the HML locus. The corrected sequence contains, in HML, an open reading frame (ORF) of 190 codons which ends at the border between the W segment and the flanking DNA. In the MAT locus, this ORF extends in the flanking DNA up to 538 codons. This ORF corresponds to a gene independently identified as BUD5 (Chant et al., 1991). This gene presents homologies with the exchange factors SDC25 and CDC25. A large ORF of 1399 codons is found on the opposite side of MATα (toward the telomere). This ORF corresponds to a new gene YCR724. Next to this gene is a small ORF, YCR725, of 127 codons. The localization of this fragment on chromosome III, originally supposed to be distal from the MAT locus based on genetic distance, illustrates variation in recombination frequency along the chromosome and suggests the existence of hot spots of recombination between MAT and the THR4 locus.