bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anxiolytic and anticonvulsive activity of Sesbania grandiflora leaves in experimental animals
Authors: Kasture Veena S. , Deshmukh V. K. , Chopde C. T. 
Published: August 2002

AbstractVarious parts of Sesbania grandiflora have been used in the Indian system of medicine, in particular, the leaves of S. grandiflora are used in Ayurveda for the treatment of epileptic fits. In the present study we have evaluated the anticonvulsive activity of S. grandiflora leaves using a variety of animal models of convulsions. Bioassay guided separation was also carried out to identify the fraction possessing anticonvulsant activity. The benzene:ethyl acetate fraction (BE) of the acetone soluble part of a petroleum ether extract significantly delayed the onset of convulsions in pentylenetetrazol (PTZ) and strychnine (STR)‐ induced seizures in mice and reduced the duration of tonic hindleg extension in the maximum electroconvulsive shock (MES) induced seizures in mice. The BE contained a triterpene as a major component. In addition, the BE also inhibited electrically induced kindled seizures in mice and lithium‐pilocarpine‐induced status epilepticus in rats. It prolonged the duration of sleep induced by pentobarbital and antagonized the effect of D‐amphetamine. Mice treated with BE preferred to remain in the open arm of the elevated plus maze indicating anxiolytic activity. The BE raised the brain contents of gamma‐aminobutyric acid and serotonin. Thus the triterpene containing fraction of S. grandiflora exhibits a wide spectrum of anticonvulsant profile and anxiolytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
DFT study of electronic structure of saccharin, thiosaccharin, and their respective ions: Effects of metal coordination on thiosaccharinate electronic structure
Authors: Branda M. M. , Castellani N. J. , Tarulli S. H. , Quinzani O. V. , Baran E. J. , Contreras R. H. 
Published: August 2002

AbstractA rationalization of the conspicuous different abilities of saccharin and thiosaccharin to form coordination compounds with the first series of transition metal elements and to interact with heavy metal cations is sought. Their electronic molecular structures as well as those of their respective ions are compared performing natural bond orbitals (NBO) analyses of the four species. Upon deprotonation, the negative charge at the N atom in saccharin is almost constant while it decreases in thiosaccharin and the negative charge at the monocoordinated chalcogen atom is notably more increased in the latter than in the former. Apparently, the negative charge reorganization makes difficult the coordination of thiosaccharin with the first series of transition metal elements and favors its experimentally observed interaction with heavy metal cations such as cadmium, lead, mercury, silver, and thallium. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Density functional complete study of hydrogen bonding between the water molecule and the hydroxyl radical (H2O · HO)
Authors: Zhou Zhengyu , Qu Yuhui , Fu Aiping , Du Benni , He Faxin , Gao Hongwei 
Published: August 2002

AbstractThe hydrogen bonding complexes formed between the H2O and OH radical have been completely investigated for the first time in this study using density functional theory (DFT). A larger basis set 6‐311++G(2d,2p) has been employed in conjunction with a hybrid density functional method, namely, UB3LYP/6‐311++G(2d,2p). The two degenerate components of the OH radical 2Π ground electronic state give rise to independent states upon interaction with the water molecule, with hydrogen bonding occurring between the oxygen atom of H2O and the hydrogen atom of the OH radical. Another hydrogen bond occurs between one of the H atoms of H2O and the O atom of the OH radical. The extensive calculation reveals that there is still more hydrogen bonding form found first in this investigation, in which two or three hydrogen bonds occur at the same time. The optimized geometry parameter and interaction energy for various isomers at the present level of theory was estimated. The infrared (IR) spectrum frequencies, IR intensities, and vibrational frequency shifts are reported. The estimates of the H2O · OH complex's vibrational modes and predicted IR spectra for these structures are also made. It should be noted that a total of 10 stationary points have been confirmed to be genuine minima and transition states on the potential energy hypersurface of the H2O · HO system. Among them, four genuine minima were located. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Computing upper and lower bounds using Monte Carlo methods
Authors: Alexander S. A. , Coldwell R. L. 
Published: August 2002

AbstractWe computed lower bounds for some ground and excited states of the helium atom using variational Monte Carlo and the Weinstein, Temple, and Stevenson formulas. For these systems, the Temple and Stevenson bounds are approximately the same and have similar standard deviations. The Weinstein bounds are much further from the actual energies and have much larger standard deviations. We also investigated the reliability of these lower bound formulas when nonorthogonal wave functions are used. The Temple formula has been shown to produce an accurate lower bound even under such circumstances, while the Weinstein and Stevenson formulas are shown to yield incorrect results. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Role of electronic structure of ruthenium polypyridyl dyes in the photoconversion efficiency of dye‐sensitized solar cells: Semiempirical investigation
Authors: Srikanth K. , Marathe V. R. , Mishra Manoj K. 
Published: August 2002

AbstractZINDO/S calculations on cis‐Ru(4,4′‐dicarboxy‐2,2′‐bipyridine)2(X)2 and cis‐Ru(5,5′‐dicarboxy‐2,2′‐bipyridine)2(X)2 complexes where X = Cl−, CN−, and NCS− reveal that the highest occupied molecular orbital (HOMO) of these complexes has a large amplitude on both the nonchromophoric ligand X and the central ruthenium atom. The lowest‐energy metal to ligand charge transfer (MLCT) transition in these complexes involves electron transfer from ruthenium as well as the halide/pseudohalide ligand to the polypyridyl ligand. The contribution of the halide/pseudohalide ligand(X) to the HOMO affects the total amount of charge transferred to the polypyridyl ligand and hence the photoconversion efficiency. The virtual orbitals involved in the second MLCT transition in 4,4′‐dicarboxy‐2,2′‐bipyridine complexes have higher electron density on the COOH group compared to the lowest unoccupied molecular orbital and hence a stronger electronic coupling with the TiO2 surface and higher injection efficiency at shorter wavelengths. In comparison, the virtual orbitals involved in the second MLCT transition in 5,5′‐dicarboxy‐2,2′‐bipyridine complexes have lesser electron density on the COOH group, leading to a weaker electronic coupling with the TiO2 surface and therefore lower efficiency for electron injection at shorter wavelengths for these complexes. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Space hybrids
Authors: Rees D. , Hall G. G. 
Published: August 2002

AbstractThe theory of defining localized functions as simultaneous eigenfunctions of commuting matrices representing the variables x, y, and z is developed further to include r, the radial variable. The appropriate complete basis set for use when the weight function in the scalar product is an exponential is described. Hybrid functions that are each strongly localized around a center are defined as eigenfunctions and can be used to describe the electron density of an atom. The hybrid centers lie at the vertices of regular polyhedra centered on the nucleus. The hybrids have the important property of vanishing at the centers of all the other hybrids. Two simple examples are given to illustrate the theory and the methods of calculation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
FTIR study of the electronic metal–support interactions on platinum dispersed on silica modified with titania
Authors: Hoffmann Helena S. , Staudt Paula B. , Costa Tania M. H. , Moro Celso C. , Benvenutti Edilson V. 
Published: August 2002

AbstractInfrared spectroscopy, using carbon monoxide as probe molecule, was utilized to detect the electronic metal–support interactions on platinum dispersed on silica modified with different titania amounts. The spectral features produced by the electronic metal–support effects were observed only for the materials that present a high titania content and they are related to the crystal titania lattice. Copyright © 2002 John Wiley & Sons, Ltd.
Ultrathin SiO2 on Si II. Issues in quantification of the oxide thickness
Authors: Seah M. P. , Spencer S. J. 
Published: August 2002

AbstractAn analysis is made of various quantification issues concerning the analysis of ultrathin layers of SiO2 on (100) and (111) polished Si surfaces. For analysis of the oxide thickness, a simple equation is generally used involving two parameters; the attenuation length of photoelectrons in the oxide and the ratio, Ro, of the intensities of the Si 2p peak from bulk thermal SiO2 and from pure Si. An analysis of previously reported measurements of the attenuation length gives an average value of only 6% less than the theoretical value. However, careful measurements of Ro, via two routes, indicate consistently that a value of 0.88 ± 0.03 should be used rather than the calculated value of 0.53 ± 0.05. This difference may arise through systematic uncertainties in the values for the relevant inelastic mean free paths, the silicon dioxide density and the shake‐up contributions. Previously reported experimental values of Ro range from 0.67 to 0.87. Uncertainties also arise from intensity variations caused by the crystal structure of the substrate. These are mapped and a position ‘A’ is found where further work is best conducted. For the (100) surface, A is 34° from the surface normal in an azimuth midway at 22.5° between the [010] and [011] azimuths. For the (111) surface at A is 25.5° from the surface normal in the [101] azimuth. Data for much of the present work are for the (100) surface at an angle of emission of 27° at position ‘B’ at 28.5° from the surface normal in the [110] azimuth, which is equivalently good but may degrade for spectrometers with high angular resolution. If the same equation is used for calculating the thickness, position B leads to a calculated thickness that is 4% less than that measured for an average orientation, whereas data acquired for normal emission lead to a value 18% lower, and those measured at A are 2% higher. Measurements of the carbonaceous contamination confirm earlier conclusions that the contamination is better described using data for an average polymer than for glassy carbon. © Crown copyright 2002. Published by John Wiley & Sons, Ltd.
Characterization of molecularly imprinted composite membranes using an atomic force microscope
Authors: Hilal Nidal , Kochkodan Victor , Al‐Khatib Laila , Busca Gerald 
Published: August 2002

AbstractAtomic force microscopy (AFM) has been used to investigate the surface structure of molecularly imprinted polyethersulphone (PES) membranes and to quantify pore size and surface roughness. Molecularly imprinted polymeric (MIP) membranes were developed using photoinitiated copolymerization of 2‐hydroxyethyl methacrylate as functional monomer and trimethylopropane trimethacrylate as crosslinker in the presence of adenosine 3′ : 5″‐cyclic monophosphate as template, followed by deposition of a MIP layer on the surface of (PES) microfiltration membranes. Atomic force microscopy images clearly indicate that a consistent increase in the degree of modification leads to a systematic decrease in pore size and an increase in surface roughness. These results show a good correlation with the filtration data of cAMP solutions. Thus, it was shown that direct AFM quantification of key parameters of imprinted membrane structure provide useful guidelines for the development of novel MIP composite membranes. Copyright © 2002 John Wiley & Sons, Ltd.
Thin films of Sr2FeMoO6 grown by pulsed laser deposition: preparation and characterization
Authors: Santiso J. , Figueras A. , Fraxedas J. 
Published: August 2002

AbstractWe report the first in situ XPS analysis of thin epitaxial films of the ferromagnetic double perovskite Sr2FeMoO6, which have been prepared by pulsed laser deposition on (100) SrTiO3 substrates under different oxygen pressures. The films consist mainly of the c‐axis‐oriented SFMO phase over a wide range of oxygen pressure (10−8–10−4 mbar) as determined by ex situ x‐ray diffraction measurements. However, different secondary phases are observed, depending on the preparation conditions. When obtained in ultrahigh vacuum conditions (10−8 mbar) the films show the presence of metallic Fe, whereas when prepared under pure oxygen gas flow (pressures above 10−6 mbar ) the Fe3O4 phase is observed. The in situ XPS analysis suggests the formation of the SrFeO3 phase in addition to SFMO, whereas the SrMoO4 phase is formed at oxygen pressures above 10−4 mbar. Copyright © 2002 John Wiley & Sons, Ltd.
The state of metal surfaces after blasting treatment Part I: Technical aluminium
Authors: Possart Wulff , Bockenheimer Clemens , Valeske Bernd 
Published: August 2002

AbstractThe aluminium–magnesium alloy EN‐AW 5754 is studied with SEM, energy‐dispersive x‐ray imaging (EDX), AES and XPS after treatment by chemical etching and blasting with glass beads or alumina grit. Blasting proves to change more than the surface profile. The freshly treated surfaces are fully covered with a carbon contamination of characteristic oxygen content ‘etch ≪ glass ≪ grit’ and average thickness ‘grit ≪ glass ≪ etch < 10 nm’. Beneath the carbon, an oxide mix is found as a continuous layer on the Al matrix. The oxide Na2O is transferred from both blast materials whereas CaO is observed after glass bead treatment only. Etching almost removes Mg but blasting retains traces of MgO. On the etched surface, the oxide layer (average thickness: glass ≪ etch ≪ grit < 10 nm) is Al2O3. Just after blasting with glass or alumina Al2O2.9 and Al2O1.3, respectively, are detected. After glass blasting, these Al atoms continue to oxidize whereas the incomplete Al oxide is almost stable after alumina blasting. These findings show that blasting produces particular chemical states that rule the interaction between the aluminium alloy and another material such as a coating or adhesive. Copyright © 2002 John Wiley & Sons, Ltd.
Room‐temperature oxidation of Fe(100), Fe(100)–3.5 wt.% MoN and segregated MoN: a mathematical analysis
Authors: Conradie R. , Roos W. D. , Swart H. C. 
Published: August 2002

AbstractThe room‐temperature oxidation of Fe(100), Fe(100)–3.5 wt.% MoN and a segregated MoN layer were compared with each other by using Auger electron spectroscopy. The linear least‐squares method was applied successfully to the low‐energy Fe AES peaks to obtain the fraction of metal and oxide as a function of oxygen exposure time. The backscattering term is, however, a function of the oxide coverage and an illogical decrease in the oxide thickness at higher exposures were measured. The high‐energy Auger peak‐to‐peak heights of Fe were also used to calculated the oxide thickness at different exposure times and these oxide thickness values were used to calculate the backscattering term for the different oxides as a function of exposure time. The backscattering term for the segregated MoN layer on the Fe(100)–3.5 wt.%MoN specimen is a combination of the backscattering from MoN, the iron oxide and the substrate. The profile indicates how important the change in the backscattering term may be for accurate surface concentration calculations. The backscattering terms for the Fe(100) and Fe(100)−3.5 wt.% MoN decrease exponentially with an increase in the oxygen exposure, which is in direct correlation with the logarithmic growth law of the oxides on the samples. Copyright © 2002 John Wiley & Sons, Ltd.
Comparison of source functions obtained by using QUASES and partial intensity analysis for inelastic background correction: KLL Auger spectra of 3d transition elements Cu and Ni
Authors: Kövér L. , Tougaard S. , Werner W. S. M. , Cserny I. 
Published: August 2002

AbstractCorrection of photoelectron and Auger spectra excited from solids for the effect of electron scattering is a key problem in quantitative surface analytical applications of XPS and AES. Based on analysis of the spectral shape of the background caused by scattering of the signal electrons, powerful methods have been developed recently and applied successfully for obtaining the ‘source functions’ (i.e. the background‐corrected spectra) as well as the in‐depth concentration profile from the measured spectra.The QUASES analysis has been proposed as a general tool for quantification in XPS, probing depths up to ∼10 inelastic electron mean free paths (λ) using Tougaard's ‘universal’ cross‐section for inelastic scattering and the λ(E) values recommended by Powell and Jablonski. Effects of elastic scattering and surface excitations are neglected with this approach and intrinsic excitations are considered a part of the source function.In the partial intensity approach, the observed spectrum can be decomposed into its constituent parts, i.e. the source function as well as contributions due to intrinsic bulk losses and surface extrinsic losses. This is achieved for an arbitrary emission mechanism. In particular, elastic scattering and different scattering mechanisms at different depths can be accounted for simply and consistently.Both methods have been applied for background correction of KLL Auger spectra of the 3d transition metals Cu and Ni excited by photons from metallic thin films vacuum‐evaporated onto Si substrates. The respective source functions obtained are very similar, especially in the case of thinner films, indicating that elastic scattering and surface effects play only a minor role in influencing the spectral shape at these high energies. A detailed analysis of the differences is given, focusing on the contributions from intrinsic excitations. Copyright © 2002 John Wiley & Sons, Ltd.
Surface and electrochemical study of DBSA‐doped polypyrrole films grown on stainless steel
Authors: Prissanaroon W. , Brack N. , Pigram P. J. , Liesegang J. , Cardwell T. J. 
Published: August 2002

AbstractElectrically conducting polypyrrole films doped with dodecylbenzenesulphonic acid (PPy–DBSA) have been electrochemically polymerized on stainless steel. The surface and electrochemical properties of the films were investigated by a combination of cyclic voltammetry (CV), scanning electron microscopy (SEM) and x‐ray photoelectron spectroscopy (XPS). The CV results showed an irreversible reaction of electropolymerization. All PPy–DBSA films had a nodular or cauliflower‐like surface morphology. The grain size was dependent on the growth current density and the growth time. The ratio of incorporated DBSA anions to pyrrole repeat units in the films was ∼1 : 2. The doping level, calculated from the positive charge accumulated in the polymer chain (at.% ratio (N+ + N2+)/Ntotal), varied as a function of the growth current density and the growth time. The maximum doping level occurred at a growth current density of 0.5 mA cm−2, consistent with an oxidation peak of the pyrrole monomer observed by CV. The interfacial layer between the polymer and substrate was also studied. A sulphur‐rich layer was observed, indicating the presence of a thin layer of DBSA at the interface. In addition, iron was detected on the metal side of the film as a result of its dissolution from the stainless‐steel electrode during the electropolymerization process. These results have implications for the use of polypyrrole films as environmentally friendly corrosion mitigants. Copyright © 2002 John Wiley & Sons, Ltd.
Multivariate survival analysis with doubly‐censored data: application to the assessment of Accutane treatment for fibrodysplasia ossificans progressiva
Authors: Jones Geoffrey , Rocke David M. 
Published: August 2002

AbstractFibrodysplasia ossificans progressiva is a rare genetic disorder in which the joints of patients become disabled by the formation of heterotopic bone. Data are available on the status of 11 joints of each of 21 patients before, during and after treatment with Accutane. These are compared with data obtained by questionnaire from 40 untreated patients to determine the efficacy of the treatment. Both left‐ and right‐censoring are present in each group, which, together with the multivariate nature of the data and the time‐dependent treatment covariate, makes analysis difficult. We consider two alternative parametric models for incorporating within‐subject dependence: a marginal model and a frailty model. Both analyses suggest that Accutane treatment is effective. We discuss and illustrate the differences between the two approaches. We also discuss the extent to which the conclusions are compromised by the observational nature of the study. Copyright © 2002 John Wiley & Sons, Ltd.
Bias in risk estimation: application to Down's syndrome screening
Authors: Williams K. L. , Nix A. B. J. 
Published: August 2002

AbstractIn this paper we consider the bias associated with parametric estimation of a univariate or bivariate Gaussian density, and also the induced bias when these Gaussian densities are used to determine a likelihood ratio. Algebraic approximations are derived that accurately predict the relative biases obtained, verification being achieved by a simulation exercise. The expressions confirm that when estimating a univariate Gaussian density there are four Z‐scores for which there is zero bias and that relative bias increases rapidly beyond two standard deviations from the mean. The results are then extended to determine approximate confidence intervals for both the true density and the likelihood ratio. A simulation exercise confirms that the derived 95 per cent confidence intervals have coverage that ranges from 94 to 97 per cent. The results are applied to a Down's syndrome screening programme where 95 per cent confidence intervals are established for a woman's posterior odds of carrying a Down's foetus. It is shown that patients with similar posterior odds can give rise to confidence intervals for their true posterior odds that have very different widths, thus emphasizing that not all risks are of equal quality. Copyright © 2002 John Wiley & Sons, Ltd.