bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoelectron spectra of chlorofluoromethanes
Authors: Cvitaš T. , Güsten H. , Klasinc L.
Published: February 2003

The photoelectron spectra of CFCl3, CF2Cl2, and CF3Cl have been recorded using Hei and Heii excitation. The relative intensities of the systems show a marked dependence on the energy of exciting radiation. The predominantly fluorine localized electrons have a greater ionization cross section for high energy (Heii) radiation while those localized mainly near the chlorine atoms have a greater ionization cross section for the low energy radiation.The spectra were assigned down to 25 eV on the basis of mutual comparison and by correlation with the assignments for chloro and fluoromethanes. The high resolution spectra revealed in some systems vibrational fine structure which is also discussed.
Spectroscopy and relaxation of Pb2 in rare gas solids
Authors: Bondybey V. E. , English J. H.
Published: February 2003

Study of emission and laser excitation spectra of the Pb2 diatomic species in rare gas solids provides a value of 112 cm−1 for the vibrational frequency in the ground (probably X 0g+) state of the molecule. In light of this conclusion we re-examined and reassigned the existing gas phase data. We observe that internal conversions into nearby electronic states are fast compared with direct vibrational relaxation within the upper state. The matrix data provide evidence for at least four other low lying electronic states.
Reactions of modulated molecular beams with pyrolytic graphite IV. Water vapor
Authors: Olander D. R. , Acharya T. R. , Ullman A. Z.
Published: February 2003

The reaction of water vapor with the prism plane face of anneal pyrolytic graphite was investigated by modulated molecular beam–mass spectrometry methods. The equivalent water vapor pressure of the beam was ∼2×10−5 Torr and the graphite temperature was varied from 300 to 2500°K. The mechanism was deduced from three types of experiments: isotope exchange utilizing modulated H2O and steady D2O beams; measurements of the phase difference between H2O and neon reflected from the surface from a mixed primary beam of these species; and reaction of a modulated H2O beam to produce CO and H2. Based upon the isotope exchange experiments chemisorption of water on graphite was found to be dissociative and reversible. Incident water molecules chemisorbed with a sticking probability of 0.15±0.02 to form the complexes C–OH and C–H. Recombination of the surface complexes reverses the adsorption step and is responsible for the isotope exchange properties of the graphite surface. This process is unactivated. Reaction to produce CO and H2 also results from collisions of the primary surface complexes, but this step has an activation energy of 170 kJ/mole. This reaction yields bound complexes tentatively identified as C–O and H–C–H, which then decompose to produce the stable reaction products. All of the above steps exhibit characteristic times on the order of milliseconds, and are therefore detectable by the modulated beam method. All surface intermediates are strongly affected by solution and diffusion in the bulk of the solid.
She4p/Dim1p Interacts with the Motor Domain of Unconventional Myosins in the Budding Yeast,Saccharomyces cerevisiae
Authors: Toi Hirofumi , Fujimura-Kamada Konomi , Irie Kenji , Takai Yoshimi , Todo Satoru , Tanaka Kazuma
Published: February 2003

She4p/Dim1p, a member of the UNC-45/CRO1/She4p (UCS) domain-containing protein family, is required for endocytosis, polarization of actin cytoskeleton, and polarization of ASH1 mRNA in Saccharomyces cerevisiae. We show herein that She4p/Dim1p is involved in endocytosis and actin polarization through interactions with the type I myosins Myo3p and Myo5p. Two-hybrid and biochemical experiments showed that She4p/Dim1p interacts with the motor domain of Myo3/5p through its UCS domain. She4p/Dim1p was required for Myo5p localization to cortical patch-like structures. Using random mutagenesis of the motor region of MYO5, we identified four independent dominant point mutations that suppress the temperature-sensitive growth phenotype of the she4/dim1 null mutant. All of the amino acid substitutions caused by these mutations, V164I, N168I, N209S, and K377M, could suppress the defects of endocytosis and actin polarization of the she4/dim1 mutant as well. She4p/Dim1p also showed two-hybrid interactions with the motor domain of a type II myosin Myo1p and type V myosins Myo2p and Myo4p, and was required for proper localization of Myo4p, which regulates polarization of ASH1 mRNA. Our results suggest that She4p/Dim1p is required for structural integrity or regulation of the motor domain of unconventional myosins.
pathSCOUT™: exploration and
analysis of biochemical pathways
Authors: Minch E. , de Rinaldis M. , Weiss S.
Published: February 2003

Motivation: pathSCOUT™ provides access, display and exploration of data relevant to biochemical pathways, and enables analysis of pathway model structure and behavior.

Availability: pathSCOUT™ is available as a customized solution from contact@lionbioscience.com; limited evaluation access and additional information is available from http://simpath.lionbioscience.com:8080/documents/pathscout11/

Contact: eric.minch@lionbioscience.com

* To whom correspondence should be addressed.
Unconventional metalworking fluids
Authors: Hörner Dietrich
Published: February 2003

Outlines the increasing use of unconventional metalworking fluids as one of the measures necessary for manufacturing industries to take to maintain their competitiveness, focusing on Germany. Notes environmental concerns and describes the use of base fluids, additives and the testing compatibility with machine tool elements.
A study of magnetic fluid based squeeze film behaviour between porous circular plates with a concentric circular pocket and effect of surface roughness
Authors: Patel R.M. , Deheri G.M.
Published: February 2003

Efforts have been directed to study the magnetic fluid based squeeze film behaviour between rotating porous circular plates with a concentric pocket. The porous housing is considered to be elastically negligibly deformable with its contact surface rough. The stochastic film thickness characterizing the roughness is assumed to be asymmetric with non‐zero mean and variance. Expressions for pressure distribution, load carrying capacity and response time are obtained in closed form. These expressions are numerically computed and the results are presented graphically as well as in tabular form.
Utilising reflective practice interviews in professional development
Authors: Chivers Geoff
Published: February 2003

There is much agreement in the literature that reflection on practice is critically important for the full development and ongoing learning of professionals. The methods of reflection on professional practice reported to date have been developed primarily in the context of professional education in group settings led by a tutor. Research is underway into ways in which managers can be developed as learning facilitators in the workplace. However, there are increasing limitations on the significance of this approach to the continuing development of professionals. The research reported here shows that in‐depth research interviews with professionals to investigate their work and learning can play an important part in supporting their reflection in‐depth on their practice. An analysis of the processes involved, and the characteristics of the three research interviewers involved, indicates that human resource development professionals could be trained for the role of learning facilitators of professionals through 1:1 discourse in the form of in‐depth interviews.
Induction of Primary Virus-Cross-Reactive Human Immunodeficiency Virus Type 1-Neutralizing Antibodies in Small Animals by Using an Alphavirus-Derived In Vivo Expression System
Authors: Dong Ming , Zhang Peng Fei , Grieder Franziska , Lee James , Krishnamurthy Govindaraj , VanCott Thomas , Broder Christopher , Polonis Victoria R. , Yu Xiao-Fang , Shao Yiming , Faix Dennis , Valente Patricia , Quinnan, Gerald V.
Published: February 2003

We have studied the induction of neutralizing antibodies by in vivo expression of the human immunodeficiency virus type 1 (HIV-1) envelope by using a Venezuelan equine encephalitis virus (VEE) replicon system with mice and rabbits. The HIV-1 envelope, clone R2, has broad sensitivity to cross-reactive neutralization and was obtained from a donor with broadly cross-reactive, primary virus-neutralizing antibodies (donor of reference serum, HIV-1-neutralizing serum 2 [HNS2]). It was expressed as gp160, as secreted gp140, and as gp160ΔCT with the cytoplasmic tail deleted. gp140 was expressed in vitro at a high level and was predominantly uncleaved oligomer. gp160ΔCT was released by cells in the form of membrane-bound vesicles. gp160ΔCT induced stronger neutralizing responses than the other forms. Use of a helper plasmid for replicon particle packaging, in which the VEE envelope gene comprised a wild-type rather than a host range-adapted sequence, also enhanced immunogenicity. Neutralizing activity fractionated with immunoglobulin G. This activity was cross-reactive among a panel of five nonhomologous primary clade B strains and a Chinese clade C strain and minimally reactive against a Chinese clade E (circulating recombinant form 1) strain. The comparative neutralization of these strains by immune mouse sera was similar to the relative neutralizing effects of HNS2, and responses induced in rabbits were similar to those induced in mice. Together, these results demonstrate that neutralizing antibody responses can be induced in mice within 2 to 3 months that are similar in potency and cross-reactivity to those found in the chronically infected, long-term nonprogressive donor of HNS2. These findings support the expectation that induction of highly cross-reactive HIV-1 primary virus-neutralizing activity by vaccination may be realized.
Human Herpesvirus 8 Envelope Glycoprotein B Mediates Cell Adhesion via Its RGD Sequence
Authors: Wang Fu-Zhang , Akula Shaw M. , Sharma-Walia Neelam , Zeng Ling , Chandran Bala
Published: February 2003

Human herpesvirus 8 (HHV-8) or Kaposi's sarcoma-associated herpesvirus, implicated in the pathogenesis of Kaposi's sarcoma, utilizes heparan sulfate-like molecules to bind the target cells via its envelope-associated glycoproteins gB and gpK8.1A. HHV-8-gB possesses the Arg-Gly-Asp (RGD) motif, the minimal peptide region of many proteins known to interact with subsets of host cell surface integrins. HHV-8 utilizes α3β1 integrin as one of the receptors for its entry into the target cells via its gB interaction and induces the activation of focal adhesion kinase (FAK) (S. M. Akula, N. P. Pramod, F.-Z. Wang, and B. Chandran, Cell 108:407-419, 2002). Since FAK activation is the first step in the outside-in signaling necessary for integrin-mediated cytoskeletal rearrangements, cell adhesions, motility, and proliferation, the ability of HHV-8-gB to mediate the target cell adhesion was examined. A truncated form of gB without the transmembrane and carboxyl domains (gBΔTM) and a gBΔTM mutant (gBΔTM-RGA) with a single amino acid mutation (RGD to RGA) were expressed in a baculovirus system and purified. Radiolabeled HHV-8-gBΔTM, gBΔTM-RGA, and ΔTMgpK8.1A proteins bound to the human foreskin fibroblasts (HFFs), human dermal microvascular endothelial (HMVEC-d) cells, human B (BJAB) cells, and Chinese hamster ovary (CHO-K1) cells with equal efficiency, which was blocked by preincubation of proteins with soluble heparin. Maxisorp plate-bound gBΔTM protein induced the adhesion of HFFs and HMVEC-d and monkey kidney epithelial (CV-1) cells in a dose-dependent manner. In contrast, the gBΔTM-RGA and ΔTMgpK8.1A proteins did not mediate adhesion. Adhesion mediated by gBΔTM was blocked by the preincubation of target cells with RGD-containing peptides or by the preincubation of plate-bound gBΔTM protein with rabbit antibodies against gB peptide containing the RGD sequence. In contrast, adhesion was not blocked by the preincubation of plate-bound gBΔTM protein with heparin, suggesting that the adhesion is mediated by the RGD amino acids of gB, which is independent of the heparin-binding domain of gB. Integrin-ligand interaction is dependent on divalent cations. Adhesion induced by the gBΔTM was blocked by EDTA, thus suggesting the role of integrins in the observed adhesions. Focal adhesion components such as FAK and paxillin were activated by the binding of gBΔTM protein to the target cells but not by gBΔTM-RGA protein binding. Inhibition of FAK phosphorylation by genistein blocked gBΔTM-induced FAK activation and cell adhesion. These findings suggest that HHV-8-gB could mediate cell adhesion via its RGD motif interaction with the cell surface integrin molecules and indicate the induction of cellular signaling pathways, which may play roles in the infection of target cells and in Kaposi's sarcoma pathogenesis.
As
2
O
3
Enhances Retroviral Reverse Transcription and Counteracts Ref1 Antiviral Activity
Authors: Berthoux Lionel , Towers Greg J. , Gurer Cagan , Salomoni Paolo , Pandolfi Pier Paolo , Luban Jeremy
Published: February 2003

Potent drugs such as cyclosporine have provided effective probes of signal transduction pathways and, as well, of human immunodeficiency virus type 1 (HIV-1) replication mechanisms. Recently, it was reported that As
2
O
3
, a drug used to treat acute promyelocytic leukemia (PML), stimulates HIV-1 replication. We found that As
2
O
3
accelerates the kinetics of a spreading HIV-1 infection in human T cells and increases the number of cells bearing HIV-1 provirus after a single round of infection. The stimulatory effect occurred after membrane fusion and resulted in increased steady-state levels of newly synthesized viral cDNA. Stimulation was independent of HIV-1
env
and most viral accessory genes, and As
2
O
3
had no detectable effects on viral expression postintegration or virion assembly. Murine leukemia virus (MLV) transduction was enhanced by As
2
O
3
to the same extent as HIV-1 transduction, but As
2
O
3
had no additional effect on
Fv1
restriction. In contrast, As
2
O
3
largely overcame the specific block to N-tropic MLV reverse transcription posed by human Ref1. As
2
O
3
disrupts PML bodies, nuclear structures named for a major component, the PML protein. We observed no changes in PML bodies in response to HIV-1 infection. Experiments with PML-null target cells indicated that PML has no effect on HIV-1 infectivity and is dispensable for the stimulatory effect of As
2
O
3
. As
2
O
3
caused cell death in uninfected cells at the same concentrations which stimulate HIV-1 replication. Among four additional apoptosis-inducing agents, a boost in HIV-1 infectivity was observed only with carbonyl cyanide
m
-chlorophenylhydrazone, a compound which, like As
2
O
3
, disrupts the mitochondrial transmembrane potential. In summary, As
2
O
3
stimulates retroviral reverse transcription, perhaps via effects on mitochondria, and provides a useful tool for characterizing Ref1.
Inhibition of Gammaherpesvirus Replication by RNA Interference
Authors: Jia Qingmei , Sun Ren
Published: February 2003

RNA interference (RNAi) is a conserved mechanism in which double-stranded, small interfering RNAs (siRNAs) trigger a sequence-specific gene-silencing process. Here we describe the inhibition of murine herpesvirus 68 replication by siRNAs targeted to sequences encoding Rta, an immediate-early protein known as an initiator of the lytic viral gene expression program, and open reading frame 45 (ORF 45), a conserved viral protein. Our results suggest that RNAi can block gammaherpesvirus replication and ORF 45 is required for efficient viral production.
Replacement of Murine Leukemia Virus Readthrough Mechanism by Human Immunodeficiency Virus Frameshift Allows Synthesis of Viral Proteins and Virus Replication
Authors: Brunelle Marie-Noëlle , Brakier-Gingras Léa , Lemay Guy
Published: February 2003

Retroviruses use unusual recoding strategies to synthesize the Gag-Pol polyprotein precursor of viral enzymes. In human immunodeficiency virus, ribosomes translating full-length viral RNA can shift back by 1 nucleotide at a specific site defined by the presence of both a slippery sequence and a downstream stimulatory element made of an extensive secondary structure. This so-called frameshift mechanism could become a target for the development of novel antiviral strategies. A different recoding strategy is used by other retroviruses, such as murine leukemia viruses, to synthesize the Gag-Pol precursor; in this case, a stop codon is suppressed in a readthrough process, again due to the presence of a specific structure adopted by the mRNA. Development of antiframeshift agents will greatly benefit from the availability of a simple animal and virus model. For this purpose, the murine leukemia virus readthrough region was rendered inactive by mutagenesis and the frameshift region of human immunodeficiency virus was inserted to generate a chimeric provirus. This substitution of readthrough by frameshift allows the synthesis of viral proteins, and the chimeric provirus sequence was found to generate infectious viruses. This system could be a most interesting alternative to study ribosomal frameshift in the context of a virus amenable to the use of a simple animal model.
Low-T3 Syndrome
Authors: Iervasi Giorgio , Pingitore Alessandro , Landi Patrizia , Raciti Mauro , Ripoli Andrea , Scarlattini Maria , L’Abbate Antonio , Donato Luigi
Published: February 2003

Background—

Clinical and experimental data have suggested a potential negative impact of low-T3 state on the prognosis of cardiac diseases. The aim of the present prospective study was to assess the role of thyroid hormones in the prognosis of patient population with heart disease.

Methods and Results—

A total of 573 consecutive cardiac patients underwent thyroid function profile evaluation. They were divided in two subgroups: group I, 173 patients with low T3, ie, with free T3 (fT3) <3.1 pmol/L, and group II, 400 patients with normal fT3 (≥3.1 pmol/L). We considered cumulative and cardiac death events. During the 1-year follow-up, there were 25 cumulative deaths in group I and 12 in group II (14.4% versus 3%,
P
<0.0001); cardiac deaths were 13 in group I and 6 in group II (7.5% versus 1.5%,
P
=0.0006). According to the Cox model, fT3 was the most important predictor of cumulative death (hazard ratio [HR] 3.582,
P
<0.0001), followed by dyslipidemia (HR 2.955,
P
=0.023), age (HR 1.051,
P
<0.005), and left ventricular ejection fraction (HR 1.037,
P
=0.006). At the logistic multivariate analysis, fT3 was the highest independent predictor of death (HR 0.395,
P
=0.003). A prevalence of low fT3 levels was found in patients with NYHA class III-IV illness compared with patients with NYHA class I-II (χ
2
5.65,
P
=0.019).

Conclusions—

Low-T3 syndrome is a strong predictor of death in cardiac patients and might be directly implicated in the poor prognosis of cardiac patients.
Myocardial fibrosis in mice with overexpression of human blood coagulation factor IX
Authors: Ameri Afshin , Kurachi Sumiko , Sueishi Katsuo , Kuwahara Mitsuhiro , Kurachi Kotoku
Published: February 2003

Elevated circulatory levels of many blood coagulation factors are known to be a risk factor for deep vein thrombosis in humans. Here we report the first direct demonstration of a close association between elevated circulatory factor IX levels in mice with thrombosis as well as myocardial fibrosis. Transgenic mice overexpressing human factor IX at persistently high levels died at much younger ages than their cohorts expressing lower levels, or nontransgenic control animals. The median survival age of animals was inversely related to the circulatory levels of human factor IX. Prematurely dying animals had focal fibrotic lesions predominantly present in the left ventricular myocardium, and vasculatures in these lesions showed fibrin deposition. Thromboemboli were also present in other organs, including lung and brain. These observations support the hypothesis that persistently high circulatory levels of factor IX are a risk factor not only for thrombosis and/or thromboembolism, but also for myocardial fibrosis mimicking human myocardial infarction.
Growth form of TiO2
Authors: Nicolov M. F. , Woensdregt C. F.
Published: February 2003

Computation of attachment energies, which are considered to be directly related to the growth rates of the corresponding F faces of the TiO2 crystal structure, have been calculated in an electrostatic point charge model. Corrections using van der Waals attractions and Born repulsions were used in normal calculations and then in calculations of attachment energies, crystal energies and surface energies using Buckingam potentials potentials and short range potentials according to Post. With this were constructed growth and equilibrium form of TiO2 crystals.
Atomic force microscopy studies on surface morphologies of CdHg(SCN)4 crystals grown in solutions containing excessive amount of Cd(II) cations
Authors: Jiang X. N. , Xu D. , Sun D. L. , Yuan D. R. , Zhang Q. Y.
Published: February 2003

Surface morphologies of CdHg(SCN)4 (CMTC) crystals grown from solutions with excessive amount of Cd(II) cations (5%, 20% and 50% in molar ratio) have been investigated by atomic force microscopy (AFM). [Cd(SCN)n]2‐n (n ≤ 4) complex anions formed by addition of excessive Cd(II) cations in the solutions have been found to act either as growth units or impurities during CMTC crystal growth. On the prismatic faces, incorporation of [Cd(SCN)n]2‐n (n ≤ 4) complex anions as growth units leads to the formation of well‐oriented protuberance trains at the step fronts, named as “locally anisotropic crystal growth”. These protuberances become fewer, less distinct and nearly disappeared with the increase of excessive Cd(II) cations in the solutions. The pyramidal face, however, varies from regular 2D nucleation growth at a low concentration of Cd(II) to much rougher growth surfaces at high concentrations, exhibiting typical surface morphologies where crystal growth is completely inhibited by impurities. Observations in this experiment provide a new picture of crystal growth.
Fatty acid composition of wild and cultivated gilthead seabream (Sparus aurata) and sea bass (Dicentrarchus labrax)
Authors: Sağglık Serap , Alpaslan Mustafa , Gezgin Tuncay , Çetintürkc Kartal , Tekinay Adem , Güven Kasım Cemal
Published: February 2003

Total lipid content and fatty acid composition were determined for wild and cultivated gilthead seabream and sea bass. Fatty acid analyses were carried out by gas chromatography‐ mass spectrometry. Respective total lipid content of flesh in cultivated gilthead seabream and sea bass were 1.7‐5.0‐times those of wild samples. Palmitic acid (C16:0) and oleic acid (C18:1n‐9) were the major fatty acids respectively among the saturated fatty acids and monounsaturated fatty acids of each fish species. It is noteworthy that both linoleic acid (C18:2n‐6) and arachidonic acid (C20:4n‐6) were predominant in total n‐6 polyunsaturated fatty acids in the respective cultivated and wild types. Eicosapentaenoic acid (C20:5n‐3) and docosahexaenoic acid (C22:6n‐3) amounts were significantly higher in flesh of cultivated fish than in wild fish.
Side‐Chain‐Functionalized Dipeptides Derived from 6,5‐Fused Bicyclic Thiazolidinlactams
Authors: Tremmel Peter , Brand Jörg , Knapp Volker , Geyer Armin
Published: February 2003

Condensation of D‐arabinuronolactone (2) with L‐cysteine methyl ester yields the bicyclic thiazolidinlactam 3 as a single diastereoisomer with the new bridgehead stereocenter in the (S) configuration. Regioselective activation of the α‐hydroxy group leads to the triflate 4 without requiring protecting groups on the residual hydroxy groups. Subsequent azide exchange, reduction, and Boc protection, yields the epimeric dipeptide mimetics 6 and 7. Compound 3 forms the single acetonide 9, which permits the regioselective alkylation of the γ‐hydroxy group of the bicyclic framework. Subsequent deprotection and exchange of the α‐hydroxy functionality against a Boc‐protected amino group (13) demonstrates the regioselective side‐chain modification of bicyclic dipeptides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
High Pressure‐Promoted [2+2] Cycloaddition Reactions of 4‐Methylphenyl 1,2‐Propadienyl Sulfone with Enol Ethers
Authors: Aben René W. M. , Braverman Samuel , Scheeren Hans W.
Published: February 2003

Under high pressure conditions, 4‐methylphenyl 1,2‐propadienyl sulfone (1) and enol ethers (6) undergo regioselective [2+2] cycloaddition reactions to give (3‐alkoxycyclobutylidene)methyl 4‐methylphenyl sulfones (7). The cycloaddition reaction has a broad scope with respect to the substituents allowed at the enol ether. The synthetic potential of the obtained cycloadducts is illustrated by a stereoselective addition of dimethylamine to the double bond of 7a and 7b to yield 11a and 11b and by a tertiary amine‐induced double bond isomerisation of 7a and 7b, followed by ring‐opening of the cyclobutene intermediate to yield 1‐alkoxybuta‐1,3‐dienes 12a and 12b. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A New, Rapid, General Procedure for the Synthesis of Organic Molecules Supported on Methoxy‐Polyethylene Glycol (MeOPEG) under Microwave Irradiation Conditions
Authors: Porcheddu Andrea , Ruda Gian Filippo , Sega Alessandro , Taddei Maurizio
Published: February 2003

The procedure for the precipitation of molecules supported on MeOPEG (molecular mass 5000) and their purification by fractional crystallization has been made easier by use of microwave irradiation. A correct choice of the solvent employed for reaction or purification (DME, THF, 1,2‐dichlorobenzene, iPrOH, ethylene glycol) allows working with 10 g of MeOPEG‐OH, dissolved in 100 mL of solvent, under microwave irradiation conditions and for crystallization to be induced just by removal of the reaction flask from the microwave oven. No additional precipitation solvents are needed, thus reducing the reaction times and the potential hazards of working with large amounts of flammable solvents. The syntheses of several peptides and of a tetrasubstituted pyridine are reported. Large amounts of MeOPEG‐OH may be used in this procedure, and so polyethylene glycol assisted organic synthesis can be regarded as a valid preparative technique. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Operator–valued Fourier multiplier theorems on Besov spaces
Authors: Girardi Maria , Weis Lutz
Published: February 2003

Presented is a general Fourier multiplier theorem for operator–valued multiplier functions on vector–valued Besov spaces where the required smoothness of the multiplier functions depends on the geometry of the underlying Banach space (specifically, its Fourier type). The main result covers many classical multiplier conditions, such as Mihlin and Hörmander conditions.
Explaining the growth of international R&D alliances in China
Authors: Li Jiatao , Zhong Jing
Published: February 2003

This paper explores two key research questions: (1) what are the growth trends of international research and development (R&D) collaborations in China; and (2) what factors determine the choice of international R&D alliance objectives in terms of a research or development orientation? It examines the rapid growth of international R&D alliances in China over the 1995–2000 period and explains multinational firms' motivations for undertaking R&D investments there. Based on the 276 international R&D alliances established in China over the study period, the paper examines the effects of some key alliance factors such as location, nationality and nature of partners, experience of partners, and alliance structure on the choice of international R&D alliance objectives in China. The findings suggest that location, number of partner, nature of local partner, and national origin of foreign partner are significantly related to the formation of research‐oriented alliances. Copyright © 2003 John Wiley & Sons, Ltd.
Absolute rate constants for the reaction of O(3P) atoms with a series of olefins over the temperature range 298–439 °K
Authors: Atkinson R. , Pitts J. N.
Published: February 2003

Absolute rate constants for the reaction of O(3P) atoms with ethylene, propylene, 1-butene, isobutene, cis-2-butene, and trans-2-butene have been determined over the temperature range 298–439 °K using a flash photolysis–NO2 chemiluminescence technique. The Arrhenius expressions obtained are: k2(ethylene) =9.23×10−12 e−(1475±200)/RT, k2(propylene) =1.05×10−11 e−(515±200)/RT, k2(1-butene) =1.39×10−11 e−(665±200)/RT, k2(isobutene) =1.76×10−11 e−(85±200)/RT, k2(cis-2-butene) =1.21×10−11 e(235±200)RT, and k2(trans-2-butene) =2.26×10−11 e(20±200)/RT cm3 molecule−1 sec−1. These data are in excellent agreement with a recent modulation–phase shift study.
Application of stochastic theory to vibration–rotation inelasticity in the He–H2 system
Authors: Augustin Stuart D. , Rabitz Herschel
Published: February 2003

Previous papers considered describing molecular collisions by the techniques of nonequilibrium statistical mechanics. In the present work this stochastic theory of molecular collisions is applied to vibration–rotation inelasticity in the He4–(para-H2) system. Some improvement in the theory is presented to better handle energetic effects, particularly important in the weak coupling limit. The resulting formulation leads to the solution of simultaneous Fokker–Planck and master equations for the rotational and vibrational motion, respectively. Scattering cross sections were computed for total energies from 1.3 to 4.0 eV. At this highest energy 85 vibration–rotation states of H2 are energetically accessible. Very strong near-resonant vibration–rotation inelasticity was found from the high rotational levels (j∼18). The results are compared to quantum mechanical calculations and experimental measurements.
Intermolecular electronic and vibrational energy transfer from the single vibronic levels of p-difluorobenzene (1B2u) to cyclobutanone
Authors: Volk Leonard J. , Lee Edward K. C.
Published: February 2003

An attempt has been made to measure the singlet–singlet electronic energy transfer rates from 17 single vibronic levels (SVL) of p-C6H4F2(1B2u) to cyclobutanone. No variation in the energy transfer cross sections have been found for the 17 SVL transitions, and an average value of 103 Å2 (πσc2) is obtained. This value is nearly identical to the value obtained for the vibrationally relaxed, thermal levels. The reason for the lack of variation is suggested to be the consequence of rapid, intramolecular vibrational energy redistribution induced by collisional perturbation.
Projections of length distributions of self-avoiding random walks used to simulate macromolecules
Authors: Wall Frederick T. , Seitz William A.
Published: February 2003

Random walks, used to simulate flexible macromolecules, have statistical distributions of end-to-end separations that can be expressed either in terms of a full set of spacial coordinates or through projections on particular axes. If the walks are long enough, the distributions exhibit spherical or circular symmetry, a property which gives rise to certain integral equations relating radial distributions to distributions by components. It is shown, among other things, how the radial distribution of lengths for two dimensional walks can be obtained from a knowledge of the distribution projected on an axis. From the solution so obtained it is proved that, if the walks are self-avoiding, a projected distribution must exhibit a minimum at the origin, a fact that has been observed.
Method of the orthonormality-constrained variation: A pair of basis sets and the pair-orthogonality
Authors: Morikawa Tetsuo
Published: February 2003

The orthogonality between sets of basis vectors, referred below to as pair-orthogonality, is examined from a variational point of view. Both how to constitute pair-orthogonal vectors and how to retain the pair-orthogonality conditions in the course of variation are presented. The relation of the vectors to canonically orthonormalized Löwdin vectors is noted.
Electron mobilities in liquid tetramethylsilane at temperatures up to the critical point
Authors: Cipollini Ned E. , Allen Augustine O.
Published: February 2003

Electron mobilities have been measured as a function of temperature over the whole liquid range of tetramethylsilane. Above the triple point, the mobility attained a minimum at 260 K and a maximum at 377 K then fell abruptly to a relatively low value near the critical point. This behavior has been shown by rare gas liquids as well as liquid 2,2,dimethylpropane; however, in tetramethylsilane the ratio of maximum to minimium mobilities was much smaller than in any of these other liquids.
The spherical Compton profile of neopentane and the carbon–carbon single bond of diamond
Authors: Reed W. A. , Snyder L. C. , Eisenberger P. , Pinder X. J. , Weber T. , Wasserman Z.
Published: February 2003

The spherically averaged Compton profile of neopentane is measured and also calculated from an ab initio SCF–MO wave function. The measured Compton profile of diamond, corresponding to a carbon–carbon bond (C–C), is compared is empirical C–C profiles computed from experimental and theoretical profiles for neopentane, ethane, and methane. We conclude that the localized bond model works well in all cases examined.
E–e Jahn–Teller system: Calculations of the low-lying energy levels
Authors: Rueff M. , Wagner M.
Published: February 2003

A localized dynamical Jahn–Teller (E–e) system is considered. The energy eigenvalues of the zero-, one-, and two-phonon states are calculated by means of the combination of a nonlinear exponential transformation and a Ritz variational procedure. They are given for the whole coupling region. In the strong coupling region the ground state is compared with the results of another transformation, that tends to be exact in that region. It turns out that the chosen procedure is exact in both extremal coupling regions and very accurate in the intermediate region.
Molecular statistical theory for inhomogeneous nematic liquid crystals with boundary conditions
Authors: Schröder H.
Published: February 2003

We start with a multipole expansion of the London-van der Waals dispersion forces between elongated cylindrically symmetric molecules as a model for the two-particle interaction. This potential is rotationally invariant and anisotropic due to both the orientation and the position of two molecules. In the next step we define a self-consistent description of orientational ordering. If a nematogenic substance is bounded by two parallel plates, a preferred direction of equilibrium orientation is induced depending on the alignment of the molecules next to the surface of the plates. The alignment near the plates will effect the degree of order throughout the whole sample thickness via the two-particle interaction. For the two cases of parallel and perpendicular alignment to the walls, we describe the resulting inhomogeneous phase by locally-variable-order parameters and investigate the temperature dependence for several sample thicknesses. It is found that the ordering induced by alignment parallel to the walls is much weaker than in the case of alignment perpendicular to the walls. This behavior corresponds to the ratio of transverse to longitudinal correlation length in nematic liquid crystals. The ratio of the correlation lengths derived from the present interaction model is found to be in excellent agreement with the ratio of the elastic constants: k33/(1/2)(k11+k22) determined from experiments.
Molecular vibrations in crystalline environments: Normal mode analyses of Cs2LiCo(CN)6 and Mn3[Co(CN)6]2⋅xH2O
Authors: Rafalko J. J. , Swanson B. I. , Jones Llewellyn H.
Published: February 2003

The Raman and infrared spectra have been recorded for the 12C14N, 13C14N, 12C15N, and 13C15N isotopes for Mn3[Co(CN)6]2⋅xH2O. In addition to the above isotopic species, the 6Li and 7Li complexes of Cs2LiCo(CN)6 were also observed. These data have been used to obtain a general quadratic potential function for Cs2LiCo(CN)6 and the A1g and Eg potential constants for Mn3[Co(CN)6]2⋅xH2O. The Mn–N force constant has been estimated for Mn3[Co(CN)6]2⋅xH2O using the A1g and Eg symmetry force constants. The unusual strength of the Mn–N interaction has been attributed to a dπ–pπ* interaction between the manganese and the nitrogen end of the cyanide. Implications regarding intervalence transfer bands in Prussian blue and its analogs are discussed.
Kerr effect and orientation relaxation of pretransitional domains and individual molecules in positive dielectric liquid crystals
Authors: Schadt M.
Published: February 2003

Measurements are reported on the static and the dynamic pretransitional behavior of the electrical birefringence (Kerr effect) of strongly positive dielectric anisotropic liquid crystals. The exceptionally large Kerr constants measured exceed that of nitrobenzene by more than a factor of 200 near the nematic to isotropic transition temperature. The orientation relaxation of the pretransitional domains of highly correlated molecules was investigated using ac-driven Kerr cells. Two relaxation processes with relaxation times in the range 10−7–10−8 sec were found to determine the dynamics of the domain relaxation. The respective processes are shown to be due to an induced and a permanent dipolar relaxation of the domains. The orientation relaxation times of the individual molecules were determined in the nematic state as well as in the pretransitional domains in the isotropic phase by measuring the conductivity relaxation.
Electronic to vibrational energy transfer from Br(42P1/2) to CO2, COS, and CS2
Authors: Hariri A. , Wittig C.
Published: February 2003

In this paper, we report a study of the quenching of Br(42P1/2) by CO2, COS, and CS2. Laser photolysis of gas samples containing Br2 and the molecular species of interest produces Br(42P1/2), and the subsequent quenching of this species results in vibrational excitation of the molecule of interest. By monitoring the time resolved ir fluorescence from Br(42P1/2) and the (001) states of CO2, COS, and CS2, we are able to measure the quenching rate coefficients for these species as well as rate coefficients for a number of V–V,T,R processes. By comparing the intensities of the Br(42P1/2) and (001) state fluorescences, we measure directly the rate coefficients for electronic to vibrational (E→V) energy transfer into the product states that contain at least one quantum of ν3 vibration.
Semiclassical theory of the effects of collisions between rotors on molecular spectral lineshapes. II. Calculations for several systems
Authors: Turfa Alexander F. , Liu Wing-ki , Marcus R. A.
Published: February 2003

The T2 (microwave line broadening) and T1 (microwave transient experiments) collisional cross sections are obtained by Monte Carlo trajectory evaluations of semiclassical (WKB) expressions for those quantities derived in a previous paper in this series. The calculated values of the cross sections presented here yields the relation T1?T2 (within standard error) for the systems OCS–OCS, OCS–N2, OCS–H2, OCS–CO2, and HCN–HCN, a result which agrees with recent experimental findings. Reasonable agreement was also found between the calculated values of the T2 cross section and those observed spectroscopically.
Triplet excimer formation and phosphorescence in fluid solutions of diarylalkanes: Excimer phosphorescence of dinaphthylalkanes and monomer phosphorescence of diphenylpropane
Authors: Okajima S. , Subudhi P. C. , Lim E. C.
Published: February 2003

The excimer phosphorescence, delayed fluorescence, and triplet–triplet absorption of α,α-dinaphthylalkanes have been investigated in isooctane at several temperatures. The results are consistent with the formation of intramolecular triplet excimers whose conformation is significantly different from that favored by singlet excimers. 1,3-diphenylpropane displays only monomerlike phosphorescence in fluid media over a wide temperature range, indicating that the binding energy of this triplet excimer is considerably smaller than that for the triplet excimers of dinaphthylalkanes.
Relation between the total energy and eigenvalue sum for neutral atoms and molecules
Authors: March N. H.
Published: February 2003

Ruedenberg has recently given arguments that the relation Etotal= (3/2) Eeigenvalue sum should hold approximately in molecules at their equilibrium configuration in self-consistent field theory. A first principles justification of this result is given here. The result has already been used in earlier work on atoms. The generalization to molecules is discussed.
State selected He–HCl collision cross sections
Authors: Monchick L.
Published: February 2003

Previous calculations of He–HCl collisions at 200 cm−1 are here extended to include some state selected cross sections, namely the integral cross sections for scattering from one jm state to another and some of the corresponding differential scattering cross sections summed over all exit channel magnetic projection quantum numbers, m′. In agreement with the coupled states approximation, the integral cross sections are found to be almost diagonal in m, and the sum of these over the exit channel projection quantum number, m′, to decrease as m increases. The amplitudes of the differential scattering patterns are found to depend on initial m very strongly at large angles, but the positions of the nodes and extrema do not. Although the coupled states approximation predicts all these features qualitatively, it tends to overestimate the size of the effect.
Zero-field mobility of excess electrons in dense methane gas
Authors: Cipollini Ned E. , Holroyd Richard A. , Nishikawa Masaru
Published: February 2003

Measurements of the low-field mobility of electrons are reported for dense methane gas above the critical temperature. Use of a thick-walled stainless steel cell permitted measurements to 200 atm or a density of 0.3 g/cc at -77°C. At low densities the mobility follows a (density)−1 dependence and increases with increasing temperature. The mobility goes through a maximum of about 1000 cm2/V sec at a density of 1×1022 molecules/cc. The variation in mobility at high densities depends primarily on fluid density and less on either fluid structure or temperature. The position of the mobility maximum is expected to correlate with a minimum in the energy of the lowest electronic eigenstate.
Chemical accelerator studies of isotope effects on collision dynamics of ion–molecule reactions: Kr++HD
Authors: Chivalak S. , Hierl P. M.
Published: February 2003

The reaction of Kr+ with HD has been studied as a function of relative collision energy over the range 0.08–3.1 eV (c.m.) by measuring integral reaction cross sections and the velocity vector distributions of product ions formed when a collimated, energy selected beam of Kr+ impinges on HD under single collision conditions. The ratio σ (KrH+)/σ (KrD+) passes through a sharp maximum (?2.5) at about 0.7 eV relative collision energy and decreases by a factor of 10 at higher energies. The isotopic product velocity vector distributions show a high but not perfect degree of symmetry about the center of mass at low energies but are extremely anisotropic at high energies, with the KrH+ being strongly forward scattered and the KrD+ being back scattered.
Self-consistent electron pair theory for certain types of open shell wavefunctions
Authors: Dykstra Clifford E.
Published: February 2003

The self-consistent electron pairs (SCEP) method is an efficient iterative scheme for the calculation of correlated molecular wavefuctions. Previous formulations of SCEP were restricted to closed shell reference states, but presented here is an extended SCEP theory for correlating open shell electrons with parallel spins, such as in triplet and quartet states. This demonstrates the applicability of SCEP to a larger class of molecular systems with the same computational efficiency as with closed shell systems.
Phase changes and molecular motion in the thiourea-cyclohexane inclusion compound
Authors: Clément R. , Mazières C. , Gourdji M. , Guibé L.
Published: February 2003

Several experimental results and discussions have previously been reported concerning the thiourea-cyclohexane inclusion compound (TCIC). They were obtained using nitrogen-14 NQR, proton wide-line NMR, relaxation time measurements, differential thermal analysis, and x ray diffraction methods. In the present paper new results of wide-line proton NMR on partially deuterated samples (thiourea-d4-cyclohexane) and a detailed interpretation of x-ray diffraction patterns are presented; the discussion leads to a better description of the behavior of the host lattice and guest molecules as the temperature of the sample is increased from −196°C to room temperature. The proposed model is also compared to that obtained for urea-trioxane, a similar inclusion compound described by the authors in an other paper.
Exponentiating trajectories and statistical behavior in collinear atom–diatom collisions
Authors: Duff James W. , Brumer Paul
Published: February 2003

The dynamic basis for statistical behavior in classical collinear bimolecular collisions is explored using an approach suggested by recent studies in nonlinear mechanics. Studies of the dynamics on three model potential energy surfaces including the Karplus–Porter H+H2 system indicate that statistical product distributions evolve from regions of the initial phase space characterized by trajectories which exponentially separate in time from nearby neighbors by more than 3 orders of magnitude. The time scale required to achieve this degree of exponential separation and associated statistical behavior is substantially shorter than that expected from arguments based on rates of intramolecular energy transfer. Our computational results also provide evidence for the validity of several assumptions implicit in the variational equations approach to determining the critical energy for energy randomization in molecular systems.
Analysis of torsional spectra of molecules with two internal C3V rotors. IX. The torsional potential functions of isobutene-d and -d6
Authors: Durig J. R. , Natter W. J. , Groner P.
Published: February 2003

The Raman spectra of gaseous isobutene (CH3)2C=CH2 and isobutene-d6 at a resolution of 1 cm−1 have been recorded between 100 and 500 cm−1. The far infrared spectra of the same compounds have been recorded over the same frequency range with a resolution of 0.5 cm−1. Several torsional transitions have been observed for both molecules and these data have been used to determine the torsional potential function based on a semirigid model. For the light molecule the average effective barrier was found to be 728±3 cm−1 (2.08±0.01 kcal/mole), and the cosine–cosine coupling term V33 has a value of 165±14 cm−1 (0.51±0.04 kcal/mole), and the sine–sine term V′33, has a value of −135±4 cm−1 (−0.38±0.01 kcal/mole). For the heavy molecule the effective barrier was found to be 719±6 cm−1 (2.05±0.02 kcal/mole) with a V33 of 49±17 cm−1 (0.14±0.05 kcal/mole) and a V′3 of −135±2 cm−1 (−0.38±0.01 kcal/mole). The barrier value compares very well with the average value of 2.21 kcal/mole reported from the microwave splittings. Comparisons are also given to similar quantities obtained for other molecules.
Langevin dynamics of a Gaussian chain
Authors: Ronca G.
Published: February 2003

The Langevin equation is applied to the calculation of the dynamics of a Gaussian ring chain in the free draining limit. An analytical expression is obtained for the correlation functions, which provides the well known t1/2 asymptotic behavior. The dynamic shear moduli are obtained in the conventional low-frequency range, and also in the high-frequency range, where G′ (ω) and G″ (ω) are shown to be independent of the molecular weight, with finite limits G′ (∞) and [ωG″ (ω)]ω→∞; these asymptotic results anticipate a discussion of the far-reaching analogy existing between the high-frequency range of the Gaussian chain and the plateau region of an entangled system.