bluuebunny/crossref_metadata_2025 huggingface dataset:
Within‐ and between‐day variability of respiratory impedance, using impulse oscillometry in adolescent asthmatics
Authors: Goldman Michael D. , Carter Rick , Klein Robert , Fritz Greg , Carter Brian , Pachucki Paul
Published: October 2002

The objectives of the present study were to: 1) assess spirometric indices and respiratory impedance with forced oscillation (FO), using impulse oscillometry (IOS) in clinically stable asthmatic children over 3 consecutive days; 2) assess FO reactance (X), using an integrated index and resistance (R) separately during inspiration and expiration; and 3) assess effects on FO of hand support of cheeks vs. no hand support. Our hypotheses were: 1) because of increased sensitivity, IOS manifests day‐to‐day variability not demonstrable by spirometry; 2) IOS R during expiration exceeds that during inspiration; and 3) hand support of cheeks affects IOS R and X only minimally. We obtained triplicate twice‐daily measures of IOS R and X in asthmatic adolescents at summer camp, in a convenience sample of children willing, with parental permission, to undergo repeated testing on consecutive days. Subjects received all medications between 6:30–7:30 AM, and were bronchodilated at time of testing. Subjects underwent IOS tests without hand support of cheeks, followed by tests with both hands supporting cheeks. ANOVA and regression analyses were used to discern technique differences.

Significant differences in IOS inspiratory R5, R5 − R15 (frequency dependence of R), and low frequency reactance area (AX) occurred across 3 days, but spirometric indices were unchanged. Inspiratory R at 5 Hz (R5) was significantly smaller than expiratory R5 (P < 0.0001). ANOVA revealed no significant differences between hand and facial muscle cheek support for IOS R and X below 15 Hz, but significant differences occurred above 15 Hz.

In conclusion, inspiratory R5, R5 − R15, and AX are sensitive measures for detecting changes in bronchomotor tone in adolescent asthmatic subjects, while expiratory R5 may be influenced by additional factors. Manual support of cheeks does not appear to affect IOS indices of peripheral airway obstruction in adolescent asthmatics. IOS is a practical method for quantifying respiratory mechanics, and its potential role in disease management warrants further study. Pediatr Pulmonol. 2002; 34:312–319. © 2002 Wiley‐Liss, Inc.
Protein folding in mode space: A collective coordinate approach to structure prediction
Authors: Abseher Roger , Nilges Michael
Published: October 2002

Does the dynamics of a protein encode its structure? Many studies have adressed the inverse of this question—how a three‐dimensional structure determines its dynamics—using molecular dynamics simulation, normal mode analysis, and similar methods. Recently we have developed a molecular dynamics (MD) simulation method to impose dynamic properties on ensembles of MD trajectories in the form of restraints on structural diversity in the directions of the principal components of motion of the molecule. In the current work, we investigate if these restraints in combination with a standard MD force field are sufficient to generate native structure in disordered structural ensembles. We present simulations from a series of increasingly disordered structural ensembles obtained by thermal unfolding or randomization of the coordinates of the native structure of two src‐homology 3 (SH3) domains. Native structure formation is observed under the sole action of the diversity restraint and the MD force field. We investigate the importance of accuracy of the description of native dynamics. Protein folding is a highly cooperative process. The dynamic restraints may enforce long‐range cooperativity and thus speed up the folding from unstructured states. Applications of the restraints to structure refinement and structure prediction are possible. Proteins 2002;49:365–377. © 2002 Wiley‐Liss, Inc.
Optimal potentials for predicting inter‐helical packing in transmembrane proteins
Authors: Dobbs H. , Orlandini E. , Bonaccini R. , Seno F.
Published: October 2002

A set of pairwise contact potentials between amino acid residues in transmembrane helices was determined from the known native structure of the transmembrane protein (TMP) bacteriorhodopsin by the method of perceptron learning, using Monte Carlo dynamics to generate suitable “decoy” structures. The procedure of finding these decoys is simpler than for globular proteins, since it is reasonable to assume that helices behave as independent, stable objects and, therefore, the search in the conformational space is greatly reduced. With the learnt potentials, the association of the helices in bacteriorhodopsin was successfully simulated. The folding of a second TMP (the helix‐dimer glycophorin A) was then accomplished with only a refinement of the potentials from a small number of decoys. Proteins 2002;49:342–349. © 2002 Wiley‐Liss, Inc.
(+)‐tiliarine, a selective in vitro inhibitor of human melanoma cells
Authors: Seal Tapan , Mukherjee Biswapati
Published: October 2002

Five diphenylbisbenzylisoquinoline (DBBI) alkaloids, tiliacorinine, tiliacorine, nor‐ tiliacorinine A, tiliarine and tiliamosine were isolated from the ethanol extract of the roots of Tiliacora racemosa Colebr. and identified by spectral techniques. Of these (+)‐tiliarine is the only one which exhibited a selective inhibitory effect against human melanoma cells (G 361) and had no activity on normal human fibroblasts (CCD 974 SK). The activity of (+)‐tiliarine against the human melanoma cell line was not much modified in the presence of calcium chloride. Copyright © 2002 John Wiley & Sons, Ltd.
Exchange contributions in the electronic structure of systems with 1D‐periodicity: Importance and computation
Authors: Delhalle Joseph , Fripiat Joseph G. , Harris Frank E.
Published: October 2002

The purpose of this article is to point out to the scientific community interested in Hartree–Fock ab initio calculations that accurate calculations of the exchange contributions are essential. An extremely simple system such as the infinite chain of Be atoms, (‐Be‐)∞, treated in direct space at the RHF level with the 3‐21G basis fails to converge to physically meaningful results. An analysis based on the convergence properties of finite Fourier series points to the exchange contributions as the source of the problem. Owing to its capability of handling with the necessary accuracy all lattice summations, including the exchange sums, the Fourier representation is able to treat the problem effectively and is confirmed as a procedure of choice for RHF electronic structure calculations of systems with 1D periodicity. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
A graph theoretical characterization of proteomics maps
Authors: Randić Milan
Published: October 2002

We consider the numerical characterization of proteomics maps based on graph theoretical invariants. A graph is associated with a map using partial ordering of map spots. From graph constructed in this way, one can extract several graph theoretical invariants. In addition, one can embed the derived graph directly over the map and characterize it by invariants of an accompanying distance matrix. Finally, we introduce an in‐between characterization of a map based on the distance‐adjacency matrix in which only distances between adjacent vertices (spots) of embedded graph are considered. The advantage of such an approach follows from the fact that the distance‐adjacency matrix is a sparse matrix which is computationally less intensive. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Mutual conversion of three flavors of Gaussian type orbitals
Authors: Mathar Richard J.
Published: October 2002

Mutual expansion formulas are developed for three types of Gaussian orbitals: Hermite Gaussians, Cartesian Gaussians, and spherical Gaussians. Overlap, kinetic energy, and Coulomb energy matrix elements are presented for generalized spherical basis functions proportional to \documentclass{article}\pagestyle{empty}\begin{document}$r^{n+s}\exp(-\alpha r^{2})Y^{m}_{n}(\hat{\mathbf{r}})$\end{document} where \documentclass{article}\pagestyle{empty}\begin{document}$Y^{m}_{n}$\end{document} represents spherical harmonics, where −n≤m≤n, and where s=0,2,4,… . Hartree–Fock benchmark calculations on isolated, neutral 2He, 6C, and 12Mg atoms indicate that inclusion of the s≥2 generalized functions is slightly unfavorable if the electronic ground state energy is to be minimized. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Density functional study on geometry and electronic structure of nitrile hydratase active site model
Authors: Nowak W. , Ohtsuka Y. , Hasegawa J. , Nakatsuji H.
Published: October 2002

Nitrile Hydratase (R. Sp. 771, NHase, EC. 4.2.1.84, CAS registration no. 82391‐37‐5), the enzyme that plays an important role in the industrial production of acrylamide, is studied theoretically in this article. For the first time the electronic structure of the active site of nitrosylated form with a proper oxidation state of the cysteine ligands is calculated using the density functional theory (DFT) method with the Becke, Lee, Yang, and Paar (B3LYP)6‐31G* functional. The optimized geometries of six and five coordinated complexes are different, showing that the photodissociation of NO triggers a substantial relaxation of the NHase active site. The major structural change is a shift of the position of iron with respect to the four equatorial ligands, which resembles a heme doming observed in myoglobins. Calculated charge distribution supports the role of Fe as a possible Lewis acid in catalytic cycle. We found that the cysteine‐sulfinic residue (Cys112) is very strongly polarized in NHase. Sulfur atom Sγ Cys112 is predicted to be the most positively charged center. This result gives independent support to a very recent finding of the critical role of an oxidation in the position Cys112 for preserving catalytic activity of the enzyme (Endo, I.; Nojiri, M.; Tsujimura, M.; Nakasako, M.; Nagashima, S.; Yohda, M.; Odaka, M. J Inorgan Biochem 2001, 83, 247). © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Quantum molecular modeling of quercetin—Simulation of the interaction with the free radical t‐BuOO⋅*
Authors: Vasilescu D. , Girma R.
Published: October 2002

Quercetin is one of the most potent antioxidants belonging to the flavonoids, which are a naturally occurring family of molecules. The optimized forms of the 3′‐, 4′‐, 3‐, 5‐, and 7‐quercetin radicals were computed using ab initio procedure at the 6‐31G* level. We have deduced that the 3′‐, 4′‐, and 3‐radicals are the most energetically favored. The simulation of the H abstraction at the 4′‐hydroxyl of quercetin by the free radical t‐BuOO⋅ (tert‐butyl peroxyl) was conducted using the supermolecular model composed of quercetin in interaction with t‐BuOO⋅. The mechanism of the scavenging of the free radical by quercetin is discussed on the basis of various AM1 and ab initio (level 6‐31G*) quantum molecular computations and the obtained frontier orbitals and total spin density. The analysis of the spin density around the obtained free radical 4′‐quercetin indicates that the major density of spin α(↑) is concentrated in the B ring on the O4′ oxygen; we observe also a slight delocalization of spins α(↑) and β(↓) on the B ring and on a part of the C ring. In conclusion, the antioxidant power of quercetin may be associated mainly with the B ring and a half of the C ring. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Some observations on P.‐O. Löwdin's definition of a molecule
Authors: Sutcliffe Brian
Published: October 2002

In a talk given in 1986 in honor of Prof. Raymond Daudel, Löwdin famously defined a molecule in the following quantum mechanical terms: “A system of electrons and atomic nuclei is said to form a molecule if the Coulombic Hamiltonian H′—with the centre of mass motion removed—has a discrete ground state energy E0.” We examine this definition in the context of chemical thinking about a molecule and attempt to place it in the context of the developments since the time of that talk. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
A note suggesting an approximation for the Hohenberg and Kohn functional*
Authors: Massa Lou
Published: October 2002

An approximation is given for calculation of the Hohenberg and Kohn (HK) functional. This follows from reduced density matrices which are functionals of the experimental electron density, obtained from X‐ray scattering, Clinton's equations, and conditions for N‐representability by correlated‐determinant wave functions. As these wave functions are known to be of accurate form, an analogous degree of accuracy is expected for the HK functional approximation which flows from them. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Valence states of the cyano radical Feynman's way
Authors: Sorensen Thomas E. , England Walter B.
Published: October 2002

Scaled Feynman diagrams are proposed as perturbative corrections to the total energy. The proposal is tested by calculating potential energy curves for the valence states of the cyano radical. Unique features of the valence state are part of the starting approximation. The latter is computed with a standard quantum chemical method. For a particular method, the scale is independent of the valence state. At each bond distance, one set of quasiparticles and Feynman diagrams is used for all valence states. Scaling will be useful whenever perturbative corrections can be expressed with Feynman diagrams. In the cyano radical, competition for the odd electron between the σ and π orbitals produces a variety of valence states. Many are quasidegenerate. The 16 states investigated here are doublets and quartets with triple bonds, double bonds, ‘resonance’ bonds, bonds intermediate to double and triple bonds, and bonds intermediate to single and double bonds. Energy curves and spectroscopic constants are reported for the lowest lying quartets and two or more lowest doublets of Σ±, Π, and Δ symmetries, and also 12Φ symmetry. Inner and outer minima in the energy curve for 32Π are assigned to H and G, respectively. A more accurate assignment of a4Σ+ is made. Relative to experiment, maximum (average) errors in bond distance, frequency, and the adiabatic excitation energy are 1.6 pm (1 pm), 60 cm−1 (50 cm−1), and 19 kJ/mol (5 kJ/mol), respectively. The error in the ground state dissociation energy is 11 kJ/mol. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
An examination of substituent effects on the stabilization of a silicon–selenium double bond
Authors: Liao Hsin‐Yi , Su Ming‐Der , Chu San‐Yan
Published: October 2002

Substituent effects on the potential energy surface of X2SiSe (X=H, F, Cl, Br, SiH3, and CH3) were investigated by using the B3LYP and QCISD(T) methods. Our theoretical findings suggest that either electronegative or steric effects play a dominant role in determining the relative stability of X2SiSe and XSi–SeX. That is to say, our model calculations indicate that both dihalogen and dibulky substituted silaneselones are more stable than their isomeric silylene species thermodynamically and kinetically. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Important fluctuation dynamics of large protein structures are preserved upon coarse‐grained renormalization*
Authors: Doruker Pemra , Jernigan Robert L. , Navizet Isabelle , Hernandez Rigoberto
Published: October 2002

The fluctuations and important motions of three large proteins—hemaglutinin, xanthine dehydrogenase, and β‐galactosidase—have been considered with a range of models having various levels of detail to represent the structures. Because the slowest modes of motion are the largest contributors to the total motions, and because these motions depend mainly on the shapes of the structures rather than their details, it is possible to replace the real structures with significantly fewer points and still retain the essential features of the structure for these modes of motion. We obtain excellent results, both for the magnitudes of the individual motions as well as for the molecular changes occurring during these motions. Similar results are obtained with another completely different approach where the coarse graining is based on invariant regions of structure found by comparing two structures of the same protein, given as an example here for myosin. Results confirm the important coupling of local functional motions with the large‐scale motions, implying important functional roles for the entire protein structure. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Prediction of the existence of radon carbonyl: RnCO
Authors: Malli Gulzari L.
Published: October 2002

Our ab initio all‐electron relativistic Dirac–Fock (DF) and nonrelativistic (NR) Hartree–Fock (HF) limit self‐consistent field molecular calculations predict the existence of radon carbonyl RnCO with the predicted dissociation energy of 4.81 and 4.22 eV, respectively. The calculations were performed for the linear RnCO at Rn–C and C–O bond distances of 2.38 and 1.12 Å, respectively. The relativistic DF dissociation (atomization) energy of the cation RnCO+ is, however, calculated to be 6.31 eV, indicating thereby that the highest occupied molecular spinor of RnCO is an antibonding molecular spinor. The ionization potential of RnCO calculated with our relativistic DF and NR HF wavefunctions is 7.73 and 7.99 eV, respectively. Mulliken population analysis of our relativistic DF (NR HF) wavefunction for RnCO yields population on C and O of −0.26 and +0.31 (−0.39 and −0.08), respectively. The bond dissociation energy of Rn–CO is calculated to be ∼28 kcal/mol. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Differences between the CO and NO properties for stability of alkali metal complexes Me(XO)n+, X=C or N
Authors: Larin Alexander V. , Trubnikov Dmitrii N. , Vercauteren Daniel P.
Published: October 2002

The influence of electron density redistribution upon vibrational excitation ν←0 on the interaction energy between CO and the metal atom Me in Me(CO)n+ carbonyls, n=1–3, is discussed. It is shown that the decrease of the CO dipole in the carbonyls upon vibrational excitation is qualitatively similar to the one of CO in the gas state. The respective decrease of the total energy of carbonyl complexes mainly due to the electrostatic repulsion Me+–C+O− (ν>6) is estimated herein for positively charged carbonyl complexes with Me=Li, Na, K, or Rb, upon the proposition of a strong coupling between the CO vibration and the electronic excitation of the whole complex. The difference between the NO and CO ligands with respect to their vibrational excitation is discussed. Also the appearance of angular bicarbonyls in adsorbed state in zeolite frameworks is considered. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Liquid chromatography/tandem mass spectrometry for the determination of fluoxetine and its main active metabolite norfluoxetine in human plasma with deuterated fluoxetine as internal standard
Authors: Li Chuan , Ji Zhouhua , Nan Fajun , Shao Qingxiang , Liu Ping , Dai Jieyu , Zhen Jiang , Yuan Hao , Xu Fang , Cui Jian , Huang Bin , Zhang Meiyun , Yu Cheng
Published: October 2002

Fluoxetine (F) and its N‐demehylated metabolite norfluoxetine (NF) are selective inhibitors of serotonin reuptake in humans. A new sensitive rapid method for the simultaneous determination of F and NF in plasma was established and validated, and was further applied to assess the bioequivalence of two oral formulations of F in 22 healthy Chinese male volunteers who received a single oral dose of each formulation (containing 20 mg of fluoxetine hydrochloride). The new method involves using liquid chromatography/tandem mass spectrometry (LC/MS/MS) in multiple reaction monitoring mode with deuterated fluoxetine (DF) as internal standard. High levels of analytical sensitivity and specificity of MS/MS detection enabled use of a simple liquid‐liquid extraction procedure. The combination of a simple sample clean‐up procedure and short chromatographic run‐time (5 min) considerably increased the productivity of the analytical method. The method was validated for the plasma concentration range 0.27–22 ng/mL for both of the test compounds, and the calibration curves were linear with coefficients of correlation >0.999. The limit of detection was 0.1 ng/mL for plasma F and NF. Taking the plasma sample size (200 µL) into account the new method for determination of F and NF is more sensitive than those described previously. Copyright © 2002 John Wiley & Sons, Ltd.
Electrochemically assisted Fenton reaction: reaction of hydroxyl radicals with xenobiotics followed by on‐line analysis with high‐performance liquid chromatography/tandem mass spectrometry
Authors: Jurva Ulrik , Wikström Håkan V. , Bruins Andries P.
Published: October 2002

Oxygen radicals are generated in vivo by various processes, often as toxic intermediates in different metabolic transformations, and have been shown to play an important role for a large number of diseases. In this article we introduce an electrochemical flow‐through system that allows generation of hydroxyl radicals for reaction with xenobiotics and subsequent detection of the oxidation products on‐line with high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). The system is based on the Fenton reaction and is predominantly aimed at the generation of hydroxyl radicals; however, by minor variations to the system, a broad range of other radicals can be produced. Optimization of the system was performed with the radical scavenger 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO). Under the same physical conditions, one injection through the electrochemical cell gave a higher yield of the oxidation product N‐hydroxy‐5,5‐dimethylpyrrolidin‐2‐one than what was attained after 60 min with a chemical Fenton system catalyzed by ascorbic acid. Since the iron is added as Fe3+, the initial mixture is ‘inactive’ until it reaches the electrochemical cell. This makes it very suitable for on‐line analysis of the generated compounds, since the whole reaction mixture, including substrate, can be kept in a vial in an autosampler. The system described provides a useful tool for investigation of new radical scavengers and antioxidants. Since the hydroxyl radical adds readily to unsaturated π‐systems, the technique is also suitable for on‐line generation and characterization of potential drug metabolites resulting from hydroxylation of double bonds and aromatic systems. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative evaluation of improvement ratio of image S/N in the NMR phase‐scrambled Fourier imaging technique
Authors: Kanzaki Nobuhiro , Ito Satoshi , Kamimura Yoshitsugu , Yamada Yoshifumi
Published: October 2002

A phase‐scrambled Fourier transform imaging technique with a signal description algorithm similar to a Fresnel transform algorithm, which can be implemented by adding some changes to a conventional MRI system, can reduce noise in the image area without degrading resolution and can improve the S/N ratio of an image, even if the noise properties are unknown. This study presents two image S/N‐improvement methods in the phase‐scrambled Fourier imaging technique and quantitatively compares the extent of improvement of the image S/N ratio of the two methods by computer simulations. The results show that both methods 1 and 2 improve the image S/N ratio by a factor of about 1.3 at the maximum without degrading resolution or creating artifacts. In addition, applying the improvement methods to NMR signals collected by the phase‐scrambled Fourier transform imaging technique using the prototype MRI system that we have constructed confirms the same extent of improvement in the image S/N ratio as in the simulation results. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(12): 27–37, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10209
Moving object extraction using background difference and region growing with a spatiotemporal watershed algorithm
Authors: Sakaida Shinichi , Naemura Masahide , Kanatsugu Yasuaki
Published: October 2002

In this paper, we describe a new method for moving object extraction based on a background image subtraction method to be applied to an object‐based picture coding system. Since this method requires a background image, we have to represent the background from a moving picture that has been shot already. We propose a new method in which the background image is reproduced by a temporal histogram of each pixel in the picture and a watershed algorithm is employed for region growing to acquire precise edge detection of the moving objects. Furthermore, a spatiotemporal watershed algorithm is introduced in order to prevent judder of the extracted objects. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(12): 11–26, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10237
Deformation and cutting algorithm of an organ model used for a laparoscopic surgery simulator
Authors: Tanaka Toshiyuki , Ito Hiroaki , Miyashita Teruo
Published: October 2002

With the recent development of endoscopic instruments, laparoscopic surgery has come into widespread use. Compared to traditional open abdominal surgery, the method offers a reduction of the physical burden on the patient, the in‐hospital period, and the recovery period. On the other hand, more technical training is required compared to open surgery, since the surgery is conducted by observing a two‐dimensional image obtained by lapar‐oscopy. Many simulators for training have been developed in various research institutions. Most of these, however, require expensive high‐performance hardware, and there is a need for a low‐cost PC‐based virtual laparoscopic surgery simulator. The important issues in constructing such a simulator are a forceps input device and an organ model representation which can be deformed or cut. This paper reports both a forceps input device and an organ model which can be deformed and cut. The organ model consists of a mass‐spring model. In the deformation algorithm, an equation for force‐displacement balance is used. When the forceps contacts an object, mismatching of the model deformation is eliminated by fine segmentation of the area surrounding the point of contact. When an object is to be cut, the fine segmentation area surrounding the area of contact with the forceps is enlarged with the progress of the incision area, maintaining the continuity of the process. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(12): 1–10, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10247
Parallel algorithms for selection on the BSP and BSP* models
Authors: Ishimizu Takashi , Fujiwara Akihiro , Inoue Michiko , Masuzawa Toshimitsu , Fujiwara Hideo
Published: October 2002

In this paper, we propose parallel algorithms to solve the selection problem on the Bulk‐Synchronous Parallel (BSP) model and the BSP* model. The BSP and BSP* models are recently proposed parallel computation models. They can represent the communication cost, a vital element in the latest parallel computations, in terms of the parameters of the synchronization period L, the reciprocal g of the communication network bandwidth, and the packet size it B. In this paper, we propose a parallel algorithm having an internal computation time O[(n/p) + dlogploglogn + L(logploglogn)/(logd)] and a communication time O[g(n/p) + (gd + L)(logploglogn)/(logd)], on the BSP model, and a parallel algorithm having an internal computation time O[(n/p) + dlogploglogn + L(logploglogn)/(logd)] and a communication time O[g(n/(pB)) + (n/p)1/7(logp)6/7) + (gd + L)(logploglogn)/(logd)] on the BSP* model for any integer d(1 ≤ d ≤ logn) to solve the problem of selecting n data with p processors. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(12): 97–107, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1170
XPS analysis of sol–gel‐generated mixed‐oxide layers for biomedical application
Authors: Schenk‐Meuser K. , Velten D. , Eisenbarth E. , Biehl V. , Duschner H. , Breme J.
Published: October 2002

The excellent biocompatibility of titanium and its alloys is associated with the properties of their dense TiO2 layer on the surface. The adsorption of proteins of the body fluid to implant surfaces depends on the properties of the surface oxide layer, especially the electronic structure. Therefore, tailoring of the oxide layer is a method for influencing protein adsorption. In this study, titanium platelets are coated by the sol–gel process with mixed oxides containing the biocompatible elements Ti, Nb, Zr and Ta. In order to verify the composition of the produced oxide layer, which can differ from the adjusted precursor composition in the sol because of different reactivities of the precursors, the layers were analysed with x‐ray photoelectron spectroscopy by carrying out sputter profiles. It was proved that the composition of a mixed‐oxide layer prepared by the sol–gel process can be tailored by the use of mixed precursors. Copyright © 2002 John Wiley & Sons, Ltd.
Contribution of surface analytical techniques for the microchemical study of archaeological artefacts
Authors: Ingo G. M. , Angelini E. , Bultrini G. , De Caro T. , Pandolfi L. , Mezzi A.
Published: October 2002

Since the 18th century many analytical methods have been used to identify the chemical composition of archaeological artefacts, the provenance of the raw materials and the technical aspects of the manufacturing process. These techniques generally probe the bulk chemical and structural features of the objects and overlook surface characteristics often essential for understanding the manufacturing techniques and the ageing processes. This work describes the contribution of x‐ray photoelectron spectroscopy (XPS) combined with bulk analytical techniques such as scanning electron microscopy + energy − dispersive spectrometry (SEM + EDS), inductively coupled plasma mass spectrometry (ICPMS) and x‐ray diffraction (XRD) by discussing the origin of the embrittlement of some selected series of silver Republican Roman coins and the study of the microchemical nature of black and coral red glosses on Attic figured vases. The results show that XPS, if allowance is made for contamination or unrepresentative or non‐homogeneous samples, complements the existing bulk analytical techniques and can provide detailed information about the surface chemical nature of the archaeological objects, as well as about their present state, and lead to recommendations for restoration and preservation. Copyright © 2002 John Wiley & Sons, Ltd.
Atomically controlled processing for group IV semiconductors
Authors: Murota Junichi , Matsuura Takashi , Sakuraba Masao
Published: October 2002

Atomic‐order surface reaction processes on the group IV semiconductor surface are formulated based on the Langmuir‐type surface adsorption and reaction scheme. In in situ doped Si1−xGex epitaxial growth on the (100) surface in an SiH4–GeH4–dopant (PH3, B2H6 or SiH3CH3)–H2 gas mixture, the deposition rate, the Ge fraction and the dopant concentration are explained quantitatively by assuming that the reactant gas adsorption/reaction depends on the surface site materials and that the dopant incorporation in the grown film is conducted by Henry's law. The self‐limiting formation of 1–3 monolayers of group IV or related atoms in the thermal adsorption and reaction of hydride gases (SiH4, GeH4, NH3, PH3, CH4 and SiH3CH3) on Si(100) and Ge(100) is also generalized based on the Langmuir‐type model. The Si epitaxial growth over the phosphorus layer already formed on Si(100) by PH3 treatment is achieved.

Moreover, atomic layer‐by‐layer etching of Si and Ge is achieved by alternate chlorine supply and irradiation of low‐energy Ar+ ions, where the chlorine adsorption is described by the Langmuir‐type model. Silicon nitride is also etched layer by layer via a role‐share method with an argon and hydrogen mixed plasma.

These results open the way to atomically controlled processing for ultra‐large‐scale integration. Copyright © 2002 John Wiley & Sons, Ltd.
Electrochemical reduction of CO2 at copper electrodes and its relationship to the metal surface characteristics
Authors: Momose Y. , Sato K. , Ohno O.
Published: October 2002

The selectivity of H2, CO, CH4 and C2H4 produced during the electrolysis of CO2 in aqueous solution at copper electrodes has been investigated in relation to surface analysis of the electrodes after electrolysis by XPS and temperature‐programmed photoelectron emission (TPPE) and surface potential (SP) measurements. The electrodes were prepared as follows: (A) only ultrasonic cleaning in acetone; (B) oxidation in air; (C) exposure to argon plasma. The electrolysis time was 3 h at a given potential. With electrode A, on increasing the potential in a negative direction the amount of CH4 increased, accompanied by a decrease in the amounts of H2 and CO, and the SP value was positive and shifted in a more positive direction, the TPPE activity increased and in the O1s XPS spectra a peak assigned to adsorbed oxygen developed. The amount of C2H4 was greater in the potential range where both metallic Cu and Cu2O existed. With electrode B, the main product was H2, the SP value was negative, the TPPE activity was much smaller and Cu2O existed more preferentially than metallic Cu. With electrode C, the surface underwent oxidation easily when immersed in solution. With increasing plasma treatment time the hydrocarbon products decreased, the SP value was lower and the TPPE activity was smaller. It is suggested that the adsorbed oxygen present at the electrode surfaces can lead to an increase in the number of electrons available at the surfaces and also contribute to the adsorption of CO2, resulting in hydrocarbon production. Copyright © 2002 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy studies of CVD diamond films
Authors: Fan Y. , Fitzgerald A. G. , John P. , Troupe C. E , Wilson J. I. B.
Published: October 2002

In this research work, a comparative x‐ray photoelectron spectroscopy (XPS) analysis has been performed on three allotropic carbon materials i.e. amorphous carbon films, graphite crystals and chemically vapour deposited (CVD) diamond films. These studies have shown that XPS is one of the most powerful techniques used to distinguish the diamond phase of carbon from the graphite and amorphous carbon components. In these investigations, particular attention has been paid to the effects of the post‐deposition surface treatment on the diamond surfaces and the corresponding spectrum changes. The experimental results confirmed that ion surface cleaning destroys the original carbon atomic bonding configuration and implants argon atoms into the sample surface. The main spectral changes for amorphous carbon, graphite and diamond materials after the ion etching process can be attributed to bonding modification and the existence of argon contamination on the sample surfaces. Copyright © 2002 John Wiley & Sons, Ltd.
Atomic force microscopy imaging and cutting of beaded carbon nanotubes deposited on glass
Authors: Singjai P. , Songmee N. , Tunkasiri T. , Vilaithong T.
Published: October 2002

We use contact force mode atomic force microscopy (AFM) to study the structures and to cut carbon nanotubes (CNTs) adsorbed on a glass slide. In addition to regular CNTs, beaded carbon nanotubes (BCNTs) were also observed when preparing products using electric current heating with the pencil technique. Imaging by contact force mode AFM could be achieved at low contact force, whereas cutting could be operated at a higher contact force in conjunction with the y‐scan direction being disabled. Cutting of BCNTs can be done without any translation of the beaded tubes. It is believed that the similar ingredients of the beaded oxides and the glass slide make them bond preferentially by chemical force. Furthermore, the morphologies were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Copyright © 2002 John Wiley & Sons, Ltd.
Dynamic modelling of a challenge‐escalation cross‐over study of treatment of capsaicin‐induced coughing
Authors: Lindsey J. K. , Stevens J. W. , Jones B. , Jackson D.
Published: October 2002

In a complex seven‐period cross‐over trial to study the effects of a drug in attenuating capsaicin‐induced coughing, counts of numbers of coughs were recorded 32 times in each period. Subjects were subjected to four escalating levels of capsaicin at each of one and five hours after treatment, with counts of coughs being recorded in four one‐minute intervals at each level. Such longitudinal count studies often show considerable individual variability about any regression curve that might be fitted. We develop a non‐linear autoregressive model for such count data that also allows for overdispersion. Copyright © 2002 John Wiley & Sons, Ltd.
Sources of stress in Australian adolescents: factor structure and stability over time
Authors: Byrne D. G. , Mazanov J.
Published: October 2002

Adolescent stress is an emerging area of importance in considerations of the health of young people. Exposure to stress predicts a range of both physical and mental health problems in adolescents and relates, as well, to the initiation of important health risk behaviours. Yet the measurement of stress in adolescents has been as fraught with methodological difficulty as it has been for adults. This paper examines the Adolescent Stress Questionnaire (ASQ) which was developed specifically to address the domain of stressors specific to adolescent experience and looks at three cohorts of responses to this questionnaire over time (1995, 1998 and 2001). It assesses the stability of the original 7‐factor structure of the ASQ over time, and while confirmatory factor analysis indicates that stability to be acceptable, it also suggests that either adolescent stressors themselves, or the language by which they are reported, vary sufficiently over time to warrant the refinement of the instrument. Copyright © 2002 John Wiley & Sons, Ltd.
Muscarinic receptors involved in the subthreshold cholinergic actions of neostriatal spiny neurons
Authors: Figueroa Alejandra , Galarraga Elvira , Bargas José
Published: October 2002

Administration of the peptide MT‐1 (48 nM), a selective agonist of muscarinic M1‐type receptors, mimicked the subthreshold actions of muscarine (1 μM) on neostriatal neurons, i.e., it produced a reduction in subthreshold inward rectification leading to an enhancement in input resistance (RN) and evoked discharge. In all recorded cells, MT‐1 effects remained in the presence of the specific peptidergic antagonist of the M4‐type receptor, MT‐3 (10 nM), but were blocked by the specific M1‐type receptor antagonist MT‐7 (5 nM). These results suggest that most muscarinic facilitatory actions in the subthreshold voltage range occur through M1‐type receptors. However, in a fraction of cells (40%) muscarine produced an excitability enhancement not blocked by MT‐7. This additional facilitatory action, not present when using MT‐1, was blocked by MT‐3, suggesting it was mediated by M4‐type receptor activation. This facilitation could not be blocked by Cs+, TTX, or Cd2+, but only by a reduction in extracellular sodium. This result is the first evidence that M4‐type receptor activation enhances a cationic inward current in a fraction of neostriatal projection neurons. Synapse 46:215–223, 2002. © 2002 Wiley‐Liss, Inc.
Endogenous cannabinoid, anandamide, acts as a noncompetitive inhibitor on 5‐HT3 receptor‐mediated responses in Xenopus oocytes
Authors: Oz Murat , Zhang Li , Morales Marisela
Published: October 2002

The cloned 5‐HT3 receptor from NCB‐20 neuroblastoma cells was expressed in Xenopus oocytes and the effect of the endogenous cannabinoid ligand, anandamide, was investigated on the function of this receptor. The oocytes expressing the cloned 5‐HT3 receptors were voltage‐clamped at −70 mV. Anandamide, at the concentration range of 0.1–100 μM, reversibly inhibited 1 μM 5‐HT induced currents. The inhibition of 5‐HT induced currents by anandamide was concentration‐dependent with an EC50 of 3.7 μM and slope value of 0.94. This inhibitory effect was not dependent on the membrane potential and anandamide did not have an effect on the reversal potential of 5‐HT‐induced currents. In the presence of 10 μM anandamide, the maximum 5‐HT‐induced response was also inhibited and the respective EC50 values were 3.4 μM and 3.1 μM in the absence and presence of anandamide, indicating that anandamide acts as a noncompetitive antagonist on 5‐HT3 receptors. CB1 receptor antagonist SR‐141716A (1 μM) and pertussis toxin (5 μg/ml) did not cause a significant change on the inhibition of 5‐HT responses by anandamide. The effect of anandamide was not changed by preincubating the oocytes with 0.2 mM 8‐Br‐cAMP, a membrane‐permeable analog of cAMP, or Sp‐cAMPS (0.1 mM), a membrane‐permeable protein kinase A activator. These results suggest that the effect of anandamide is independent of the activation of cAMP pathway and not mediated by the activation of PTX sensitive G‐proteins. In conclusion, we demonstrated that the endogenous cannabinioid anandamide inhibits the function of 5‐HT3 receptors expressed in Xenopus oocytes in a cannabinoid‐receptor independent and noncompetitive manner. Synapse 46:150–156, 2002. Published 2002 Wiley‐Liss, Inc.
Septation of the anorectal and genitourinary tracts in the human embryo: Crucial role of the catenoidal shape of the urorectal sulcus
Authors: Rogers Daniel S. , Paidas Charles N. , Morreale Robert F. , Hutchins Grover M.
Published: October 2002

Background

Previous studies of the tracheoesophageal sulcus and the sulci of the developing heart have suggested that the catenoidal or saddle‐shaped configuration of the sulcus had mechanical properties that were important to developmental processes by causing regional growth limitation. We examined the development of the human perineal region to determine if a similar configuration exists in relation to the urorectal septum. We wished to re‐examine the controversial issue of the role of the urorectal sulcus in the partitioning of the cloaca.

Methods

Digitally scanned photomicrographs of serial histologic sections of embryos from Carnegie stages 13, 15, 18, and 22, obtained from the Carnegie Embryological Collection were used. Each image was digitally stacked, aligned, and isolated using image‐editing software. Images were compiled using 3‐D image‐visualization software (T‐Vox), into full 3‐D voxel‐based volume renderings. Similarly, digital models were made of the urogenital sinus, anorectum, cloaca, allantois, mesonephric ducts, ureters, and kidneys by isolating their associated epithelium in each histologic section and compiling the data in T‐Vox. Methods were developed to create registration models for determining the exact position and orientation of outlined structures within the embryos.

Results

Models were oriented and resectioned to determine the configuration of the urorectal sulcus. The results show that the urorectal sulcus maintains a catenoidal configuration during the developmental period studied and, thus, would be expected to limit caudal growth of the urorectal septum.

Conclusion

The observations support the concept that the urorectal septum is a passive structure that does not actively divide the cloaca into urogenital and anorectal components. Teratology 66:144–152, 2002. © 2002 Wiley‐Liss, Inc.
Cloning and characterization of WMSU1, a Williopsis saturnus var. mrakii gene encoding a new yeast SUN protein involved in the cell wall structure
Authors: Guyard Cyril , Cailliez Jean‐Charles , Tissier Jean‐Pierre , Dei‐Cas Eduardo , Mercenier Annick , Menozzi Franco D.
Published: October 2002

SUN proteins of Saccharomyces cerevisiae have been defined on the basis of high homologies in their C‐terminal domain. Recently, two of these four proteins were shown to be involved in cell wall morphogenesis (Mouassite et al., 2000a). In the present study, we have isolated WMSU1 (Accession No. AF418983), a new SUN‐related gene, from W. saturnus var. mrakii MUCL 41968. Sequencing of the gene revealed an open reading frame coding for 402 amino acids. The predicted amino acid sequence of WMSU1 is closely related to the S. cerevisiae SUN proteins and to other yeast proteins involved in cell wall metabolism. WMSU1 is proposed to encode a cell wall protein since its predicted product contains a signal sequence, a Kex2p cleavage site and a serine/threonine‐rich N‐terminal domain. Southern blot analysis of the W. saturnus var. mrakii MUCL 41968 genome using the highly conserved domain of WMSU1 as a probe suggested that the isolated gene belongs to a multigenic family. Expression of WMSU1 in E. coli led to a 45 kDa protein, which appeared to be toxic to this host. Scanning electron microscopy analysis of a recombinant S. cerevisiae producing Wmsu1p showed that this strain exhibited an altered cell wall, thus pointing to a probable role of this protein in the cell wall structure. Copyright © 2002 John Wiley & Sons, Ltd.
Mesenchymal cells in the liver – one cell type or two?
Authors: Ramadori G. , Saile B , Ramadori G. , Saile B.
Published: October 2002

Abstract:  The wall of the liver sinusoid is made of highly specialized cells, the hepatic stellate cells (HSC) which together with the sinusoidal endothelial cells represent a loose barrier to the corpusculate part of the blood flowing through the liver. Quiescent stellate cells (quiescent HSC) store Vitamin A; “activated” stellate cells become involved in the reaction to acute or chronic noxae damaging the liver parenchyma. Activated HSC show increased protein synthesis capacity, increased DNA‐synthesis and acquire a myofibroblast‐like phenotype. Under similar conditions liver myofibroblasts (MF) of the portal field and of the pericentral area may also become “activated” by increasing protein synthesis, DNA synthesis and cell division. They express the fibulin‐2 gene and produce large amounts of IL‐6. In contrast to “activated” HSC they do not undergo spontaneous apoptosis in vitro and do not express the CD95‐ligand gene. So far no definite prove has been found for a “transdifferentiation” of HSC to myofibroblasts. On the contrary an increasing amount of data support the conviction that HSC and MF represent two similar but not identical cell populations the latter being comparable to those of other organs.