bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasi-three-dimensional network of molecular interactions and electronic structure of a new organic semiconductor, ET(NCS)0.77
Authors: Kazheva Olga N. , Canadell Enric , Aleksandrov Grigorii G. , Kushch Nataliya D. , Dyachenko Oleg A.
Published: July 2002

The radical cation salt ET(NCS)0.77 [bis(ethylenedithio)tetrathiafulvalene thiocyanate (1/0.77)] has been prepared for the first time by electrocrystallization and its crystal and electronic structure at 110 K was investigated. The unit-cell dimensions are orthorhombic, a = 6.638 (1), b = 8.309 (2), c = 28.776 (6) Å, V = 1587.1 (6) Å3, space group Pbcm, Z = 4. The compound has a layered structure. The ET radical cations of the conducting cationic layer build stacks. In the anionic layer the thiocyanate groups form polymeric chains where they are oriented in a `head-to-tail' mode. The structure has short intermolecular contacts of the cation–cation, anion–anion and cation–anion types, which leads to the formation of a three-dimensional structure of intermolecular interactions. This phenomenon is very rare in molecular conductors. Tight binding band structure calculations suggest, however, that the interlayer interactions through the anions are weak and that the incomplete occupation of the anion sites is the reason for the activated conductivity of the salt.
Amino-substituted O6-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures
Authors: Quesada Antonio , Marchal Antonio , Melguizo Manuel , Nogueras Manuel , Sánchez Adolfo , Low John N. , Cannon Debbie , Farrell Dorcas M. M. , Glidewell Christopher
Published: July 2002

The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O6-benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O6-alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N—H...O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines. There is a marked propensity for these nitroso compounds to crystallize with Z′ = 2. The structure of an analogue with no nitroso group is also reported for comparative purposes. Compounds containing the N-alkyl substituents —NHCH2COOEt, —NHCH2CH2COOEt and —NHCH(CH2Ph)COOEt, derived from amino acid esters, exhibit a rich variety of conformational behaviour, and in all of the nitroso compounds the bond lengths provide strong evidence for a highly polarized electronic structure. Associated with this polarization is extensive charge-assisted hydrogen bonding between the molecules, leading to supramolecular aggregation in the form of finite (zero-dimensional) aggregates, chains, molecular ladders, sheets and frameworks.
Refinement of obverse/reverse twins
Authors: Herbst-Irmer Regine , Sheldrick George M.
Published: July 2002

Two examples of structures of obverse/reverse twins are presented. Example (1) is the structure of 2,2,4,4,6,6-hexa-tert-butylcyclotrisiloxane. It crystallizes in R\overline 3c. Example (2) is the structure of [{Li(Me3Si)3CAlF3(thf)}3LiF(thf)], tris[lithiuim tetrahydrofuran (trimethylsilyl)methyltrifluoroaluminate]lithium fluoride tetrahydrofuran. It crystallizes in R3. Additional to the obverse/reverse twinning this structure shows merohedral twinning. It will be shown how these two structures can be refined with the SHELXL program.
Coupling of the lactone-ring conformation with crystal symmetry in 6-hydroxy-4,4,5,7,8-pentamethyl-3,4-dihydrocoumarin. Erratum
Authors: Budzianowski Armand , Katrusiak Andrzej
Published: July 2002

In the paper by Budzianowski & Katrusiak (2002) Acta Cryst. (2002), B58, 125–133 Figs. 5 and 8 on pages 131 and 132 were transposed while adjusting colour details indicated by the authors in the proof. Revised PDF versions of these pages are available in the online version of this erratum, which is available through Crystallography Journals Online.
Symmetry constraints, molecular recognition and crystal engineering. Comparative structural studies of urea–butanedioic and urea–E-butanedioic acid (2:1) cocrystals
Authors: Videnova-Adrabińska V.
Published: July 2002

The crystal structures of two urea–dicarboxylic acid (2:1) cocrystals have been determined. Urea–butanedioic acid forms monoclinic crystals, space group P21/c (No. 14), with a = 5.637 (4), b = 8.243 (3), c = 12.258 (3) Å, β = 96.80 (5)°, V = 565.6 (8) Å3, Z = 2. Urea–E-butenedioic acid also forms monoclinic crystals, space group P21/c (No. 14), with a = 5.540 (1), b = 8.227 (1), c = 12.426 (3) Å, β = 97.22 (3)°, V = 561.9 (2) Å3, Z = 2. The geometry and the conformation of both molecular aggregates and the three-dimensional networks formed are very similar. The two strongest hydrogen-bond interactions are constrained in the formation of the heteroaggregates, the third hydrogen-bond interaction is used to self-associate the heteroaggregates in one-dimensional chains, whereas the next three weaker hydrogen bonds interconnect the chains into well organized three-dimensional networks.
Structural and computational analysis of published neutron diffraction data show that crystalline vitamin B12 coenzyme contains a strong intramolecular N-H...Ph hydrogen bond
Authors: Starikov E. B. , Steiner T.
Published: July 2002

The neutron diffraction crystal structure of vitamin B12 coenzyme [Bouquiere et al. (1993). Acta Cryst. B49, 79–89] contains a yet unnoticed intramolecular aromatic hydrogen bond donated by a propionamide side chain and accepted by the benzimidazole group. The distance from the H-atom to the aromatic midpoint is only 2.58 Å and the bond energy is calculated to be 16.7 kJ mol−1.
Experimental Charge Density and Electrostatic Potential of Triglycine
Authors: Pichon-Pesme V. , Lecomte C.
Published: July 2002

The experimental electron density distribution in triglycine has been determined using single-crystal X-ray diffraction data at 123 K to a resolution of (sin θ/λ)max = 1.1 Å−1. Several multipolar pseudo-atom density refinements were performed against the 7238 observed data in order to estimate the net charges on the atoms. The electrostatic potential around the two molecules is calculated from the parameters derived from these refinements. A charge transfer between the two triglycine molecules of the asymmetric unit is discussed. Crystal data: C6H11N3O4, Mr
= 189.2, triclinic, P1¯, Z = 4 (two molecules in the asymmetric unit), T = 123 K, a = 11.585 (1), b = 14.603 (2), c = 4.800 (4) Å, α = 89.28 (3), β = 95.55 (2), γ = 104.484 (8)°, V = 782.5 (7) Å3, Dx
= 1.61 g cm−3, μ = 1.5 cm−1 for λMo = 0.7107 Å.
Electron density and electrostatic potential of KNiF3: multipole, orbital and topological analyses of vacuum-camera-imaging plate and four-circle diffractometer data
Authors: Ivanov Yury , Zhurova Elizabeth A. , Zhurov Vladimir V. , Tanaka Kiyoaki , Tsirelson Vladimir
Published: July 2002

The electron density and electrostatic potential of KNiF3, nickel potassium trifluoride, were studied using multipole and orbital model treatment of the precision X-ray diffraction data measured by vacuum-camera-imaging plate and four-circle diffractometer methods. Different experimental methods lead to similar multipole and atomic displacement parameters and to qualitatively the same electron densities. Good agreement was also achieved for the Laplacians of the electron density and the electrostatic potentials. Some pitfalls of the vacuum-camera-imaging plate method that could be improved are discussed.
Les colonnes cylindriques transparentes unicolores et bicolores
Authors: Roman T.
Published: July 2002

By unrolling the surface of a cylinder into a double-faced plane, the cylindrical, double-faced columns, with single-coloured (\cal j) or two-coloured (\cal j2) patterns and their symmetries, are studied. A symmetry is the isometric mapping of the column and its pattern set onto themselves, and is characterized by the retention or change of the patterns between the two faces, or by the colour-retention or colour-change of the patterns. All possible classes of these discontinuous columns are derived for the cases with and without translation. As extreme cases, the columns with an infinite-fold cylinder axis and those with an infinite screw pitch are given. For particular values of m, the rotational component order of the fundamental rototranslation, the 945 types of proper crystallographic, two-coloured, transparent, columns \cal j2
2c
are deduced. Illustrations are given for the unrolling into a double-faced plane of some types of \cal j2
2c
columns, of the two-coloured, biracial columns without translation, {\bar \cal j}2
2, and of the two-coloured, semicontinuous oblique columns.
Rigid-body motion in phosphorus chalcogenides
Authors: Forder R. A.
Published: July 2002

The thermal parameters of P4S5, P4S7, P4S10 and P4Se5 have been analysed on the basis of the rigid-body hypothesis, using both Cruickshank's and Shomaker & Trueblood's methods. For these compounds, at least with the data at present available, the fit to the rigid-body model is only moderate, and there is no significant difference in the results of the two methods. Librational corrections to bond lengths have been calculated.
When two into one won't go: fitting in the presence of steric hindrance and partial occupancy
Authors: Thouvenin Eric , Hewat Elizabeth
Published: July 2002

Combining structural data from cryo-electron microscopy (cryo-EM) and X-ray crystallography to give pseudo-atomic models of large molecular complexes has proved particularly suitable for studying viruses and viral complexes. Several groups are developing programs to fit X-ray data to EM data. These programs are in general tailored to particular problems with regard to size, symmetry, number of rigid bodies, resolution etc. Here, two approaches are described to fitting X-ray data to EM data in the presence of steric interference and their relative merits and limitations are indicated. These fitting techniques are applied to the case of the rotavirus double-layered particle (DLP) in complex with antibodies which inhibit the transcription of mRNA by the DLP. This is a particularly good test case, as the cryo-electron microscopy map of the DLP–Fab complex, the X-ray structure of the viral protein (VP6) and also that of the VP6–Fab complex are available. The estimation of partial occupancy is also considered.
Protein structure resources
Authors: Weissig Helge , Bourne Philip E.
Published: July 2002

The Protein Data Bank (PDB) is the primary source of macromolecular structure data for a worldwide community of users. A subset of those users then process these data to derive secondary information which is also available on the WWW. This process includes validation, some form of reductionism, via sequence or structure, or visualization. The result, a set of further web-accessible resources on protein structure and functional classification, links to primary genomic information, protein–protein and protein–ligand interactions, protein dynamics and protein-modeling resources. This paper reports on these processes and a subset of the web resources that result.
The Biological Macromolecule Crystallization Database: crystallization procedures and strategies
Authors: Gilliland Gary L. , Tung Michael , Ladner Jane E.
Published: July 2002

The Biological Macromolecule Crystallization Database (BMCD) archives crystallization data from published reports for all forms of biological macromolecules that have produced crystals suitable for X-ray diffraction studies. The information includes the crystallization conditions, crystal data, comments about the crystallization procedure and information on the biological macromolecule or biological macromolecule complex. Crystallization procedures, including fast screens and more general procedures, can be developed effectively using this web-based resource (http://wwwbmcd.nist.gov:8080/bmcd/bmcd.html).
Determination of the Relative Precision of Atoms in a Macromolecular Structure
Authors: Zhou Genfa , Wang Junfeng , Blanc Eric , Chapman Michael S.
Published: July 2002

Several real-space indices and temperature factors are compared with respect to their correlation with atomic positional error and their ability to indicate atoms and residues with the worst of subtle errors. The best index, r
ED, is a correlation coefficient between model and map electron densities, similar to one proposed earlier, but incorporating two improvements. Firstly, resolution is accounted for explicitly by calculating the model electron density by Fourier transformation of resolution-truncated scattering factors. Secondly, the deviation between model and map electron densities is assigned to neighboring atoms according to their contribution to the electron density of each grid point. With maps of various qualities, r
ED is the single index with best correlation to atomic error with grouped or individual atoms, and it is the most reliable indicator of poor residues. With poorer omit maps, imprecision of individual atoms is best diagnosed by a combination of low r
ED or high B factor. With the improved methods, 60–70% of the least precise atoms can detected in a fully refined structure. Similarly, 40–80% of the least precise atoms of an unrefined model can be detected by comparison with an isomorphous replacement map. This is useful in assessing and improving the quality of a model, but not sufficient to confidently validate all atoms of a structure at sub-atomic resolution.
Preliminary X-ray crystallographic analysis of a novel maltogenic amylase from Bacillus stearothermophilus ET1
Authors: Cho Moon-Ju , Cha Sun-Shin , Park Jong-Hyeok , Cha Hyun-Ju , Lee Hee-Seob , Park Kwan-Hwa , Oh Byung-Ha
Published: July 2002

A novel maltogenic amylase from Bacillus stearothermophilus ET1, which has a dual activity of α-1,4- and α-1,6-glycosidic bond cleavages and α-1,6-glycosidic bond formation, was crystallized by using the hanging-drop vapor-diffusion method. The best crystals were obtained by employing a high concentration of protein (56 mg ml−1) and a precipitant containing 22% glycerol, 1.6 M ammonium sulfate in 0.1 M Tris–HCl (pH 8.5). Native diffraction data to 2.66 Å resolution have been obtained from crystals flash-frozen at 110 K. The crystals belong to the space group P212121 with unit-cell dimensions of a = 77.62, b = 121.23, c = 244.29 Å, and contain three or four protomers per asymmetric unit. Structure determination by multiple isomorphous replacement is in progress.
First Experimental Evidence for Human Dentine Crystal Formation Involving Conversion of Octacalcium Phosphate to Hydroxyapatite
Authors: Bodier-Houllé Patricia , Steuer Pierre , Voegel Jean-Claude , Cuisinier Frédéric J. G.
Published: July 2002

Biological apatite-crystal formation is a complex process starting with heterogeneous nucleation of inorganic calcium phosphate on an organic extracellular matrix [Cuisinier et al. (1995), J. Cryst. Growth, 156, 443–453]. Further stages of crystal growth are also controlled by the organic matrix and both nucleation and growth processes are under cellular control [Mann (1993), Nature (London), 367, 499–505]. The final mineral in calcified tissue is constituted by poorly crystalline hydroxyapatite (HA) with a low Ca:P ratio, containing foreign ions such as carbonate and fluoride. This study reports the first observation of octacalcium phosphate (OCP) [Brown (1962), Nature (London), 196, 1048–1055] in a biological tissue; OCP was found in the central part and HA at the extremities of the same crystal of calcifying dentine. This observation is of key importance in understanding the first nucleation steps of biological mineralization. The presence of OCP in a forming human dentine crystal and the observation in the same tissue of nanometer-sized particles with a HA structure [Houllé et al. (1997), J. Dent Res.
76, 895–904] clearly proves that two mechanisms, direct nucleation of non-stoichiometric HA crystals and nucleation of OCP, occur simultaneously in same area of mineralization. OCP is found to be a transient phase during the growth of biological crystals. In small crystals, OCP is completely transformed into HA by a hydrolysis reaction (Brown, 1962) and can only be detected in larger crystals because of its slow kinetics of transformation.
Databases in Protein Crystallography
Authors: Kleywegt Gerard J. , Jones T. Alwyn
Published: July 2002

Applications of structural databases in the protein crystallographic structure determination process are reviewed, using mostly examples from work carried out by the authors. Four application areas are discussed: model building, model refinement, model validation and model analysis.
Crystallization and preliminary X-ray diffraction studies of the carboxylesterase EST2 from Alicyclobacillus acidocaldarius
Authors: De Simone Giuseppina , Manco Giuseppe , Galdiero Stefania , Lombardi Angela , Rossi Mosè , Pavone Vincenzo
Published: July 2002

EST2, a thermophilic carboxylesterase from Alicyclobacillus acidocaldarius, belonging to the HSL group of the esterase/lipase superfamily, has been crystallized for the first time. Ammonium sulfate was used as a precipitant and the crystallization proceeded at pH 7.8. The crystals belong to space group P41212 or its enantiomorph P43212, with unit-cell parameters a = b = 78.8, c = 106.4 Å. A complete data set has been collected at the synchrotron source Elettra in Trieste to 2.4 Å resolution, using a single frozen crystal.
Structure of orthorhombic crystals of beef liver catalase
Authors: Ko Tzu-Ping , Day John , Malkin Alexander J. , McPherson Alexander
Published: July 2002

The growth mechanisms and physical properties of the orthorhombic crystal form of beef liver catalase were investigated using in situ atomic force microscopy (AFM). It was observed that the crystals grow in the 〈001〉 direction by an unusual progression of sequential two-dimensional nuclei of half unit-cell layers corresponding to the `bottoms' and `tops' of unit cells. These were easily discriminated by their alternating asymmetric shapes and their strong growth-rate anisotropy. This pattern has not previously been observed with other macromolecular crystals. Orthorhombic beef liver catalase crystals exhibit an extremely high defect density and incorporate great numbers of misoriented microcrystals, revealed intact by etching experiments, which may explain their marginal diffraction properties. To facilitate interpretation of AFM results in terms of intermolecular interactions, the structure of the orthorhombic crystals, having an entire tetramer of the enzyme as the asymmetric unit, was solved by molecular replacement using a model derived from a trigonal crystal form. It was subsequently refined by conventional techniques. Although the packing of molecules in the two unit cells was substantially different, with very few exceptions no significant differences in the molecular structures were observed. In addition, no statistically significant deviation from ideal 222 molecular symmetry appeared within the tetramer. The packing of molecules in the crystal revealed by X-ray analysis explained in a satisfying way the process of crystal growth revealed by AFM.
Co-crystallization and preliminary crystallographic analysis of the high mobility group domain of HMG-D bound to DNA
Authors: Murphy Frank V. , Sehy Jonathan V. , Dow Linda K. , Gao Yi-Gui , Churchill Mair E. A.
Published: July 2002

Structural studies are essential to understand mechanisms of non-sequence-specific DNA binding used by chromosomal proteins. A non-histone high-mobility group (HMG) chromosomal protein from Drosophila melanogaster, HMG-D, binds duplex DNA in a non-sequence-specific fashion. The DNA-binding domain of HMG-D has been co-crystallized with a duplex DNA fragment in the primitive orthorhombic space group P212121, with unit-cell dimensions a = 43.74, b = 53.80, c = 86.84 Å. Data have been collected to 2.20 Å at 99 K, with diffraction observed to at least 2.0 Å. Heavy-atom derivative crystals have been obtained by co-crystallization with oligonucleotides halogenated at major-groove positions near the end of the DNA.
Charge densities from high-resolution synchrotron X-ray diffraction experiments
Authors: Mallinson Paul R. , Barr Gordon , Coles Simon J. , Guru Row Tayur N. , MacNicol David D. , Teat Simon J. , Woźniak Krzysztof
Published: July 2002

The combination of intense X-ray sources, especially synchrotron radiation, with area-detector technology has accomplished an enormous advance in the experimental conditions available for charge-density analysis by single-crystal high-resolution X-ray diffraction. Such experiments can now be carried out in a time measured in hours rather than weeks. Some features of these experiments are examined and preliminary results are reported for charge-density studies of 2-hydroxy-5-nitrobenzaldehyde N-cyclohexylimine (1), octakis(m-tolylthio)naphthalene (2), and 7-fluoro-4-styrylcoumarin (3). Weak interactions in crystals of (1) and (3) are found to have similar charge-density characteristics. Cages in the crystal lattice of (2) have a complex charge distribution.
In situ EXAFS study on metal particles dispersed on Loy Yang brown coal
Authors: Shirai Masayuki , Arai Masahiko , Murakami Kenji
Published: July 2002

The structure of nickel catalysts supported on Loy Yang brown coal by an ion-exchanging method during thermal treatment was studied by an XAFS technique. The exchanged nickel species aggregated to metal particles during pyrolysis and hydrogasification. The aggregation behaviour of nickel species depended on the amount of nickel loaded and/or treatment atmospheres.
XAFS study of copper species stabilized in the interlayer space of layered perovskite oxides
Authors: Kim Dong-Kuk , Choi Shin-Hei , Han Yang-Su , Yun Hoseop
Published: July 2002

New intercalation compounds with Cu2+ ions in the interlayer of layered perovskite oxides, OA1-xCa2-xLaxNb3O10 (OA = n-octylammonium ion, 0 ≤ x < 1), have been prepared by ion-exchange reaction, and characterized by means of XRD and XAS. For the detail elucidation of the fine structure of the Cu K-edge XANES spectra, polarized XAS was applied for the [Cu(en)2]2+ and Cu2+ ions intercalated to the single crystal. According to the XANES and EXAFS spectra measured at Cu K-edge, copper ions are four-coordinated. In addition, XANES spectra have shown that the charge transfer from host layer to intercalated ions influences on the chemical state of copper ion.
The use of prior information for extracting the post-edge background
Authors: Klementev K. V.
Published: July 2002

A new method for extracting the post-edge background µ0 is proposed, the method of Bayesian smoothing. A further evolution of the smoothing spline method is considered as well. Both techniques are capable to take into account prior information about the peculiarities on the µ0. In addition, since the Bayesian approach works in terms of the posterior probability density functions, it contains a natural way to determine the errors of the µ0 construction, which has always been an unresolvable problem for any other method. Even with use of the prior information, which narrows the posterior probabilities, the errors of µ0 are shown to be larger than the experimental noise.
XAFS at the Pacific Northwest Consortium-Collaborative Access Team undulator beamline
Authors: Heald Steve , Stern Edward , Brewe Dale , Gordon Robert , Crozier Daryl , Jiang Detong , Cross Julie
Published: July 2002

The Pacific Northwest Consortium-Collaborative Access Team (PNC-CAT) has begun operating an insertion device beamline at the Advanced Photon Source. The beamline has been extensively used for XAFS studies. This paper summarizes its capabilities, and our initial operational experience. The beamline is based on APS undulator A, and incorporates full undulator scanning. The monochromator is liquid nitrogen cooled and has both Si(111) and Si(311) crystals in a side-by-side configuration. Crystal changes only take a few minutes. The crystals cover the energy range from 3-50 keV with fluxes as high as 2 × 1013 ph/sec. Microbeams can be produced using Kirkpatrick-Baez mirrors (spot size 1-3 µm) or tapered capillaries (sub-µm spots). When these optics are combined with a 13-element Ge detector, the beamline provides powerful microbeam imaging and spectroscopy capabilities. Experimental examples from the environmental field and in situ UHV film growth will be discussed.
Progress and challenges in the theory and interpretation of X-ray spectra
Authors: Rehr J. J. , Ankudinov A. L.
Published: July 2002

There has been dramatic progress over the past decade both in theory and in ab initio calculations of X-ray absorption fine structure (XAFS). Rapid progress is now being made in understanding X-ray absorption near-edge structure (XANES). This presentation reviews the developments in this field by many groups leading up to the current state of the art. These developments have led to several ab initio codes, such as FEFF, which yield results comparable to experimental results for XAFS, and permit an interpretation of the spectra in terms of geometrical and electronic properties of a material. The review begins with a summary of the key theoretical developments that are essential for achieving a quantitative agreement with experiment for XAFS. The same high-order multiple-scattering (MS) theory of XAFS can also give an approximate treatment of XANES, but this approach can fail close to an edge, where full MS calculations are often necessary. However, a fully quantitative treatment of XANES remains challenging, largely as a result of a number of many-body effects, e.g. the approximate treatment of the core-hole, multiplet effects, the photoelectron self energy and inelastic losses. Finally, natural extensions of the theory to other spectroscopies, such as anomalous X-ray scattering, DAFS (diffraction anomalous fine structure) and XMCD (X-ray magnetic circular dichroism) are briefly discussed. These developments are illustrated with a number of applications.
Magnetic EXAFS at Gd L-edges: the spin-pair-distribution function of Gd neighbors
Authors: Wende Heiko , Wilhelm Fabrice , Poulopoulos Panagiotis , Rogalev Andrei , Schlagel Deborah L. , Lograsso Thomas A. , Baberschke Klaus
Published: July 2002

The purpose of the experiment is to study the normal and the Magnetic EXAFS (MEXAFS) since EXAFS is the method of choice to investigate the local pair- and spin-pair-distribution function. We present MEXAFS and EXAFS measurements at the L-edges of a Gd single crystal in the temperature range of 10 K to 250 K. Therefore we are able to investigate the MEXAFS in a wide range of the reduced temperature t=T/T_C of 0.04 \leq t \leq 0.85 with T_C=293 K. We find a strong decrease of the nearest neighbor EXAFS which retains only about 35\% of its 10 K value already at 250 K. This highlights the importance of lattice vibrations. To analyze the individual scattering contributions to the MEXAFS and the EXAFS, ab initio calculations (FEFF code) have been carried out. The comparison of the temperature-dependent damping of the normal EXAFS with the spin-dependent MEXAFS allows us to separate the influence of lattice vibrations (Debye temperature 160 K) from the magnetic ordering (Curie temperature) on the MEXAFS.
HF-STEX and RASSCF calculations on nitrogen K-shell X-ray absorption of purine base and its derivative
Authors: Mochizuki Yuji , Koide Hiroshi , Imamura Toshiyuki , Takemiya Hiroshi
Published: July 2002

The nitrogen K-shell X-ray absorption spectra of the purine bases present in nucleic acids, adenine and guanine, were analyzed by using ab initio Hartree-Fock static exchange and restricted-active-space self-consistent-field calculations. A variety of derivative molecules were calculated to investigate the energetic shifts due to environmental effects on the nitrogen atoms. Shake-up excitations were also addressed.
U7C beamline and XAFS station of National Synchrotron Radiation Laboratory
Authors: Xu Faqiang , Liu Wenhan , Wei Shiqiang , Xu Chaoyin , Pan Guoqiang , Zhang Xinyi , Sun Jianwei , Zhao Weichang , Cui Hongbin , Ye Weiquan
Published: July 2002

The XAFS station on beamline U7C of National Synchrotron Radiation Laboratory (NSRL) was completely constructed in December 1998. The source for XAFS station is from a 3-pole superconducting wiggler with magnetic field of 6 T inserted in the straight section of the storage ring. Using a Si(111) double crystal monochromator with a fixed slit, the X-ray intensity at the sample position is about 3 × 109 photons/second at the energy of 8980 eV of Cu K-edge. The Keithley 6517 electrometers are used to record the electron charges that are produced in the ionization chambers. A high ratio of signal to noise has been obtained for the XAFS spectra of Cu, Ni and Fe foils. Furthermore, the XAFS spectrum of Cu foil in NSRL is in good agreement with that obtained in BSRF and KEK.
Path-integral approach to anharmonic vibration of solids and solid interfaces
Authors: Yokoyama Toshihiko
Published: July 2002

The temperature dependence of EXAFS (extended X-ray absorption fine structure) cumulants was investigated for bulk Cu and a thin film of Cu by means of the path-integral effective classical potential method. By using the semi-empirical embedded-atom method as a potential, agreement between the experiments and calculations is found to be excellent for bulk Cu. In the thin Cu(111) film, anisotropic anharmonic vibration was clearly observed; the out-of-plane vibration is much more enhanced and more anharmonic than the lateral vibration. The results are semiquantitatively consistent with the previous experimental data on Cu(111)/graphite. Such a vibrational enhancement should be the driving force for the roughening transition and/or the surface pre-melting at higher temperature. The practical usefulness of the path-integral effective classical potential method combined with the embedded-atom method is demonstrated.
Ni phases formed in cement and cement systems under highly alkaline conditions: an XAFS study
Authors: Scheidegger André M. , Wieland Erich , Scheinost Andreas C. , Dähn Rainer , Tits Jan , Spieler Peter
Published: July 2002

X-ray absorption fine structure (XAFS) spectroscopy was applied to assess the solubility-limiting phase of Ni in cement and cement minerals. The study reveals the formation Ni and Al containing hydrotalcite-like layered double hydroxides (Ni-Al LDHs) when cement material (a complex mixture of CaO, SiO2, Al2O3, Fe2O3 and SO3) was treated with Ni in artificial cement pore water under highly alkaline conditions (pH = 13.3). This finding indicates that Ni-Al LDHs and not Ni-hydroxides determine the solubility of Ni in cement materials.
In situ EXAFS study of copper in the electrokinetic remediation process
Authors: Liu S.-H. , Wang H. Paul , Wang H.-C. , Yang Y. W.
Published: July 2002

The speciation of copper in the early stage of the electrokinetic remediation (EKR) process has been studied by extended X-ray absorption fine structure (EXAFS) spectroscopy in the present work. By in-situ EXAFS, we found that copper in a contaminated soil possessed a Cu-O bond distance of 1.98 Å with a coordination number (CN) of 5.8. In the second shell, the bond distance of Cu-(O)-Cu was 2.87 Å with a CN of 6.4. However, possibly due to the fact that incompact copper atoms in the outer shells were distorted by EKR, the Cu-(O)-Cu (2nd shell) bond distance and the CN of copper in the contaminated soil decreased by 0.08 Å and 5.4, respectively in the early stage of the EKR process. Interestingly, after prolonging the contact time to about 80 minutes, the 1st-shell copper atoms were also perturbed by EKR. This work is an example of usefulness of the in-situ EXAFS spectroscopy for detailed studies of the speciation of copper in the contaminated soil during EKR process.
Local structures of nanocrystalline GaN studied by XAFS
Authors: Li Zhongrui , Wei Shiqiang , Wang Ying , Zhang Xinyi , Lu Kunquan , Chen Xiaolong
Published: July 2002

X-ray absorption fine structure (XAFS) was used to investigate the local structures around Ga atoms in the hexagonal nanocrystalline and crystalline GaN under 78 and 300 K. For the first nearest neighbor coordination shell of Ga-N, the average bond length R (0.194 nm), coordination number N (4.0), thermal disorder σT (0.0052 nm) and static disorder σS (0.0007 nm) are nearly independent of the measured temperature and crystalline state. This indicates that the Ga-N covalent bond is much stronger, and the 4 nitrogen atoms in first nearest neighbor around Ga atoms keep the tetrahedral structure (Td). For the second nearest neighbor coordination shell of Ga-Ga, their bond lengths are about 0.318 nm. However, the σS (0.0057 nm) of nanocrystalline GaN is 0.0047 nm larger than that of crystalline GaN (0.001nm), and the σT of nanocrystalline is 0.0053 nm and 0.0085 nm at the temperature of 78 and 300 K, respectively. The result indicates that the difference of local structure around Ga atoms between nanocrystalline and crystalline GaN occurs mainly at the Ga-Ga second nearest-neighbor coordination shell. The reason is explained as the local lattice distortion and unsaturated surface atoms existing in nanocrystalline GaN.
Soft X-ray absorption spectra of ilmenite family
Authors: Agui Akane , Mizumaki Masaichiro , Saitoh Yuji , Matsushita Tomohiro , Nakatani Takashi , Fukaya Atsuko , Torikai Eiko
Published: July 2002

We have carried out soft x -ray absorption spectroscopy to study the electronic structure of ilmenite family, such as MnTiO3, FeTiO3, and CoTiO3 at the soft x -ray beamline, BL23SU, at t he SPring-8. The Ti and M L 2,3 absorption spectra of MTiO3 (M = Mn, Fe, and Co) show spectra of Ti4+ and M2+ eletron configurations, respectively. Except the Fe L2,3 spectrum, those spectra were understood within the Oh symmetry around the transition metal ions. The Fe L3-edge spectrum clearly shows a doublet peak at the L3 edge, which is attributed to Fe2+ state, moreover the very high-resolution the L-edge spectra of transition metals show fine structures. The spectra of those ilmenites are compared.
DXAFS study on the decarbonylation process of Mo(CO)6 in NaY supercages
Authors: Shido Takafumi , Yamaguchi Aritomo , Suzuki Akane , Inada Yasuhiro , Asakura Kiyotaka , Nomura Masaharu , Iwasawa Yasuhiro
Published: July 2002

The decarbonylation process of Mo(CO)6 in the NaY supercages was studied by means of a time resolved dispersive XAFS method during temperature programmed decarbonylation. XANES analysis demonstrated that the decarbonylation proceeded through two steps and that a stable intermediate existed between 440-490 K. The curve fitting analysis revealed that the intermediate was a molybdenum monomer subcarbonyl species coordinated by three CO ligands and three oxygen atoms of zeolite framework. Molybdenum dimer subcarbonyl species were not observed. This study demonstrated that DXAFS technique is a powerful method to study the dynamic behaviour of the Mo carbonyl species during decarbonylation process.
Double electron transitions [MN] or [MO] above 74W M
III edge in X-ray absorption spectra
Authors: Ito Y. , Vlaicu A. M. , Shigeoka N. , OhHashi H. , Mutaguchi K. , Nakata Y. , Emura S. , Grush M. , Stolte W. , Schlachter F.
Published: July 2002

The X-ray absorption spectra in metallic W (tungsten) have been measured above M
III edge using the third generation synchrotron radiation, ALS, Berkeley. Several features caused by multi-electron transitions were detected on M
III in solid phase. [3p4f], [3p5s], and [3p5p] double electron transitions were identified by the Z+1 approximation.
Production of synchrotron X-ray biprism interference patterns with control of fringe spacing
Authors: Lang A. R. , Makepeace A. P. W.
Published: July 2002

An X-ray biprism has been constructed from a pair of rectangular-section polished diamond bars meeting edge-to-edge, and rotatable about the prism axis so as to vary the convergence of the refracted beams. Interference patterns have been recorded at wavelengths of 0.08, 0.096 and 0.11 nm with good agreement between calculated and observed fringe spacings. Application of the fringe-observing arrangement employed in this work to the assessment of X-ray source characteristics is proposed.
DL-Piperidine-2-carboxylic acid
Authors: Stapleton Clynton P. D. , Tiekink Edward R. T.
Published: July 2002

A chair conformation is found for zwitterionic DL-piperidinium-2-carboxylate, C6H11NO2. Hydrogen-bonding interactions involving the carboxylate groups and ammonium H atoms give rise to a two-dimensional structure comprised of interconnected 12-membered rings.
A review of library provision in Ghana
Authors: Alemna A.A.
Published: July 2002

Provides a review of the most recent development in library provision in Ghana. Gives information on the types of libraries in the country ‐ public, academic, special and school ‐ and also deals with issues related to their development. Concludes by suggesting the establishment of a National Library for Ghana.
Teaching and learning entrepreneurship for micro and small businesses in the cultural industries sector
Authors: Raffo Carlo , Lovatt Andy , Banks Mark , O’Connor Justin
Published: July 2002

Reports on an ESRC‐funded, in‐depth qualitative research project into 50 micro and small enterprises (MSEs) in the cultural industries. Our evidence sheds light on the extent to which the teaching and learning strategies adopted by higher education, further education and other VET providers are effective in providing entrepreneurship education and training for this innovative, high skill sector. Our findings suggest that entrepreneurs in this sector learn best by being able to experiment with ideas, by “doing” and networking with others and by working with more experienced mentors in their sector. The article concludes by suggesting a more “naturalistic” approach to teaching and learning entrepreneurship for micro and small businesses in the cultural industries sector.
Transactional learning relationships: developing management competencies for effective small firm‐stakeholder interactions
Authors: Hanno Paul D. , Patton Dean , Marlow Sue
Published: July 2002

It has been argued that a critical issue pertaining to small firm success is the ability to manage and develop a network of interdependent relationships with a wide and diverse range of stakeholders. The article explores the needs of small firms and their stakeholders in building interdependent relationships as effective learning forms for enhancing a small firm’s potential to succeed. It is suggested that small firm owners and managers need to develop specific competence frameworks when initiating and progressing such relationships. It is also suggested that those managing such dyadic relationships have been disadvantaged by the lack of appropriate guidelines to assess current levels of competence and opportunities for improvement.
Workplace bullying: responding with some emotional intelligence
Authors: Sheehan Michael
Published: July 2002

This article outlines some of the signs indicating bullying in the workplace as a problem within contemporary organisations. Moreover, using evidence from recent Australian Court cases, the article mentions some of the costs organisations may be faced with if they fail to address the problem. Having identified the problem, the article then suggests some solutions including legislative change and development of more co‐operative workplaces. Such workplaces would deal with the problem in a problem solving, rather than punitive, framework. Development of people’s emotional intelligence skills is suggested as one way to help address the problem within such a framework.
An experimental study of social and psychological aspects of teleworking
Authors: Hobbs Dave , Armstrong James
Published: July 2002

The last few years have seen a growth in interest in the concept of teleworking, and current predictions suggest that this could become a common mode of working in future. This paper describes an investigation into the working environment of teleworking, examining the currently‐debated issues associated with it, and laying out the potential advantages and drawbacks. Views solicited from workers currently operating within a teleworking regime in a large UK organization are presented and discussed. A small‐scale experimental study of the psychological and sociological effects associated with teleworking is then described, and the results and implications discussed. Finally, a set of teleworking guidelines for work managers is proposed.
Knowledge gaps between participants in a triadic relationship
Authors: Horne Suzanne , Naudé Pete , Worthington Steve
Published: July 2002

Aims to expand the traditional view of marketing to include a wider network of actors, all of which have a role to play in executing transactions. Measurement has traditionally been a stumbling‐block: while the importance of actors other than those forming the traditional dyad is accepted, it has not been easy to determine empirically what it is that the different partners want from the relationship. In this paper we present a possible way forward. The preliminary work presented here is based on the affinity credit card market which has three clear partners in a triad: the bank, the affinity group itself, and the customers that elect to make use of the card. We present some early results that indicate the extent to which these three partners do, and do not, have an overlapping understanding of each other’s needs.
Temporal elements of organizational culture and impact on firm performance
Authors: Onken Marina H.
Published: July 2002

Examines two temporal elements of organizational culture, polychronicity and speed values, and their effects on organizational performance. The study of these dimensions of culture and their effects on firm effectiveness is especially relevant for leaders who are responsible for the implementation of a firm’s culture as one of the firm’s strategic resources. The impacts of these temporal elements are examined individually and within the context of hypercompetitive industries.
The effects of individual time urgency on group polychronicity
Authors: Waller Mary J. , Giambatista Robert C. , Zellmer‐Bruhn Mary E.
Published: July 2002

Recent work concerning the effects of time on group behavior suggests that individuals’ time‐oriented behaviors may act as a catalyst or pacing mechanism for subsequent group behaviors. Other work suggests that group polychronic behavior (the group’s performance of multiple tasks simultaneously) has significant effects on both individual and group outcomes. In this paper, we examine the relationship between individuals’ time‐oriented behavior and group‐level polychronic behavior. Based on results from a laboratory simulation involving 26 small groups, we conclude that the presence of time‐urgent group members increases group‐level monochronic (versus polychronic) behavior and has a positive effect on groups’ primary task activity.
Contemporary HRD research: a triarchy of theoretical perspectives and their prescriptions for HRD
Authors: Garavan Thomas N. , Gunnigle Patrick , Morley Michael
Published: July 2002

Addresses some of the key debates within the HRD literature and considers the extent to which HRD can be described as a field of study. The paper addresses the issues raised in the contributions that make up this special issue and identifies a broad range of methodologies and use of research methods. It argues that all of the contributions fit into at least one theoretical perspective: capabilities, psychological contacts and the learning organization/organizational learning. The paper concludes with a consideration of the prescriptions which the perspectives advocate for HRD in organizations.
The emergence of strategic training and development: the current state of play
Authors: Horwitz Frank M.
Published: July 2002

Evaluates how HRD needs which arise from different business strategies will depend on, among other things, the purpose and structure of the strategies involved. Considers the motivation for strategic HRD, expenditure and responsibility. Concludes that a strategic approach to training and development necessitates increased theoretical rigour, more rigorous evaluation of effectiveness, and resolution of responsibility for training.
The Test of English as a Foreign Language
Authors: Messner Phillip E. , Liu Naifa
Published: July 2002

Investigates a scientific basis for establishing the Test of
English as a Foreign Language (TOEFL) cut‐off scores. Obtains data on
348 foreign students from 50 US universities. Divides students into
three categories according to TOEFL score: below 550; 550‐600; and above
600. Measures academic success by first semester or quarter grade point
average (GPA) score. Finds a significant difference in GPA score between
international graduate students with TOEFL scores above 550 when
compared with those with scores below 550. Results support the national
trend towards raising foreign graduate student admission minimum TOEFL
scores from 500 to 550.
Research on total teacher effectiveness: conception strategies
Authors: Cheong Cheng Yin , Tung Tsui Kwok
Published: July 2002

Based on the conception of total teacher effectiveness, aims to develop strategies for conceptualizing teacher effectiveness research. From the new conception, the units of research on teacher effectiveness are cell, array and layer. The strategies advanced for conceptualizing research include the individual unit description strategies, the within‐layer relationship strategies, the between‐layer relationship strategies, and the whole structure strategy. Based on the conception strategies, teacher effectiveness research can be shifted from traditional simplistic one‐dimensional conception to sophisticated multidimensional conception and can have various research alternatives for different research purposes and contexts. Hopefully, these strategies can provide a new direction for studying and improving teacher effectiveness in particular and school effectiveness in general.
Fault detection and quality assessment in textiles by means of neural nets
Authors: Sette S. , Boullart M.L.
Published: July 2002

Quality assessment and fault detection are important topics in textile research. Human assessment in this field, however, is subjective and slow. Presents an automatic assessment using two fundamentally different kinds of neural networks: the Kohonen Map (an unsupervised system) and the backpropagation network (supervised system). Evaluates two case studies using these techniques: assessment of carpet wear and the assessment of set marks. Both show good results when applied to the aforementioned problems. Makes a comparison between the two techniques and shows that the unsupervised system also gives an evaluation of the objectivity of the human experts.
Surface appearance irregularity of nonwovens
Authors: Militký Jirí , Rubnerová Jitka , Klicoka Václav
Published: July 2002

Visual and subjective methods for evaluation of surface appearance irregularity of chemically bonded nonwovens are compared. The image analysis system LUCIA is used for estimation of characteristics describing appearance. The analysis of subjective and objective estimates of surface appearance irregularity is realized by the coefficient of variation and by the ANOVA type model.
Corporate social responsibility in food retailing
Authors: Piacentini Maria , MacFadyen Lynn , Eadie Douglas
Published: July 2002

Describes a study investigating the motivations of food retailers to engage in corporate socially responsible (CSR) activities. Focusing on confectionery retailing and merchandising, the study sought to establish the extent of CSR activities and the motivations for companies to act as they do. An audit of food retailers was first conducted to establish the nature and extent of CSR activities. This was followed by a series of in‐depth interviews with key decision makers in food retailing organisations, to reveal motivations behind their policies on confectionery retailing. The authors found the main motivations driving confectionery merchandising decisions to be space maximisation, profitability and customer pressure. While certain proactive companies recognised the benefits of being seen as a socially responsible company, none of the companies was driven primarily by philanthropic motivations.