bluuebunny/crossref_metadata_2025 huggingface dataset:
Building a new performance vision for results
Authors: LaBonte Thomas J.
Published: February 2003

Increasingly line managers are expressing frustration at receiving incomplete performance solutions, weak return on investment, and less than expected results from performance support departments that claim to have the answer for improving business results. Often there are complaints that departments such as human resources, training, information technology, and quality operate in silos and compete against each other for success rather than working together to deliver complete solutions to performance problems. Proposes that we eliminate silos and deliver complete performance solutions by adopting a new performance vision, an enterprise learning and performance strategy, and a common human performance improvement (HPI) process. Provides a definition of HPI and a five‐phase HPI process as a starting point for performance improvement departments. Critical outcomes of the process are diagnosing workplace and learning barriers to performance and designing and implementing blended performance solutions that deliver comprehensive results. New roles, competencies, and approaches to developing performance improvement expertise are required in implementing performance interventions using an HPI process. Provides a glossary of performance terms and a checklist of recommended steps for starting the transformation to HPI.
Competitive implications of information technology in the public sector
Authors: Salmela Hannu , Turunen Pekka
Published: February 2003

Increased use of market mechanisms in the delivery of public services is one of the major attempts made by governments to achieve greater efficiency, higher quality and a clearer focus on customers. Information systems (ISs) can promote the adoption of market mechanisms, but they can also preserve a monopolistic and hierarchic model of service delivery. Hence, understanding the competitive implications of information technology (IT) is becoming relevant for managers in the public sector as well. Provides a brief overview of previous research on IT‐based competition and discusses its relevance for public sector management. Then continues to describe a project where six offices of one city co‐operated in developing a shared geographic information system (GIS). While this research is based on an in‐depth analysis of only one case, other researchers have reported similar experiences. It appears that effective use of market mechanisms in the public sector requires new orientation in IS planning and rethinking of the role of IS departments in public sector organisations.
Procurement best practice in the food industry: supplier clustering as a source of strategic competitive advantage
Authors: Ryder Ray , Fearne Andrew
Published: February 2003

Looks at the way in which a pizza manufacturing company, supplying both branded and own‐label products to the Irish and UK retail markets, undertook a major restructuring of its procurement and manufacturing processes. Numerous sub‐processing activities were having adverse effects on capability utilization and manufacturing efficiency at a time of increasing demand. Process re‐engineering was required. Illustrates the approaches taken towards two projects: first, cheese supply and, second, packaging. Notes there was a steep learning curve for the management and operations staff and also resistance to change from within the firm and from some suppliers. Provides a list of critically important points learned from the experience.
Simian Virus 40 Small Tumor Antigen Induces Deregulation of the Actin Cytoskeleton and Tight Junctions in Kidney Epithelial Cells
Authors: Nunbhakdi-Craig Viyada , Craig Leonard , Machleidt Thomas , Sontag Estelle
Published: February 2003

There is increasing evidence that the transforming DNA tumor virus simian virus 40 (SV40) is associated with human malignancies. SV40 small tumor antigen (small t) interacts with endogenous serine/threonine protein phosphatase 2A (PP2A) and is required for the transforming activity of SV40 in epithelial cells of the lung and kidney. Here, we show that expression of SV40 small t in epithelial MDCK cells induces acute morphological changes and multilayering. Significantly, it also causes severe defects in the biogenesis and barrier properties of tight junctions (TJs) but does not prevent formation of adherens junctions. Small t-induced TJ defects are associated with a loss of PP2A from areas of cell-cell contact; altered distribution and reduced amounts of the TJ proteins ZO-1, occludin, and claudin-1; and marked disorganization of the actin cytoskeleton. Small t-mediated F-actin rearrangements encompass increased Rac-induced membrane ruffling and lamellipodia, Cdc42-initiated filopodia, and loss of Rho-dependent stress fibers. Indeed, these F-actin changes coincide with elevated levels of Rac1 and Cdc42 and decreased amounts of RhoA in small t-expressing cells. Notably, these cellular effects of small t are dependent on its interaction with endogenous PP2A. Thus, our findings provide the first evidence that, in polarized epithelial cells, expression of small t alone is sufficient to induce deregulation of Rho GTPases, F-actin, and intercellular adhesion, through interaction with endogenous PP2A. Because defects in the actin cytoskeleton and TJ disruption have been linked to loss of cell polarity and tumor invasiveness, their deregulation by PP2A and small t likely contributes to the role of SV40 in epithelial cell transformation.
Subcellular Localization of Herpes Simplex Virus Type 1 UL51 Protein and Role of Palmitoylation in Golgi Apparatus Targeting
Authors: Nozawa Naoki , Daikoku Tohru , Koshizuka Tetsuo , Yamauchi Yohei , Yoshikawa Tetsushi , Nishiyama Yukihiro
Published: February 2003

The herpes simplex virus type 1 (HSV-1) UL51 gene products are virion-associated phosphoproteins with apparent molecular masses of 27, 29, and 30 kDa in HSV-1-infected cells. In this study, we have investigated the intracellular localization and distribution of UL51 protein both in infected cells and in transfected cells expressing only UL51. We found that this protein colocalized closely with Golgi marker proteins such as the Golgi-58K protein and GM130 in transfected cells expressing only UL51. However, in infected cells, the UL51 protein localized to the juxtanuclear region but only partially colocalized with the Golgi maker proteins. Mutant protein analysis revealed that the N-terminal 15 amino acid residues of the UL51 protein sufficed for this Golgi localization property. The UL51 protein redistributed on addition of brefeldin A. This was prevented by pretreatment with 2-deoxyglucose and sodium azide, which results in ATP depletion, but not by pretreatment with NaF and AlCl
3
, which activates heterotrimeric G proteins. Moreover, we found that palmitoylation of the UL51 protein through the N-terminal cysteine at position 9 was necessary for its Golgi localization. Protease digestion analysis suggested that the UL51 protein localized on the cytoplasmic face of the membrane in UL51-transfected cells, while in infected cells it localized mainly to the inside of cytoplasmic vesicles and/or the viral envelope. Transmission immunoelectron microscopy revealed an association of UL51 protein-specific labeling with cytoplasmic virions and also with some membranous structure. We infer from these observations that internalization of UL51 protein into the cytoplasmic vesicle and/or virion may occur in association with viral envelopment in HSV-infected cells.
Nontransmissible Virus-Like Particle Formation by F-Deficient Sendai Virus Is Temperature Sensitive and Reduced by Mutations in M and HN Proteins
Authors: Inoue Makoto , Tokusumi Yumiko , Ban Hiroshi , Kanaya Takumi , Tokusumi Tsuyoshi , Nagai Yoshiyuki , Iida Akihiro , Hasegawa Mamoru
Published: February 2003

The formation of nontransmissible virus-like particles (NTVLP) by cells infected with F-deficient Sendai virus (SeV/ΔF) was found to be temperature sensitive. Analysis by hemagglutination assays and Western blotting demonstrated that the formation of NTVLP at 38°C was about 1/100 of that at 32°C, whereas this temperature-sensitive difference was only moderate in the case of F-possessing wild-type SeV. In order to reduce the NTVLP formation with the aim of improving SeV for use as a vector for gene therapy, amino acid substitutions found in temperature-sensitive mutant SeVs were introduced into the M (G69E, T116A, and A183S) and HN (A262T, G264R, and K461G) proteins of SeV/ΔF to generate SeV/M
ts
HN
ts
ΔF. The use of these mutations allows vector production at low temperature (32°C) and therapeutic use at body temperature (37°C) with diminished NTVLP formation. As expected, the formation of NTVLP by SeV/M
ts
HN
ts
ΔF at 37°C was decreased to about 1/10 of that by SeV/ΔF, whereas the suppression of NTVLP formation did not cause either enhanced cytotoxicity or reduced gene expression of the vector. The vectors showed differences with respect to the subcellular distribution of M protein in the infected cells. Clear and accumulated immunocytochemical signals of M protein on the cell surface were not observed in cells infected by SeV/ΔF at an incompatible temperature, 38°C, or in those infected by SeV/M
ts
HN
ts
ΔF at 37 or 38°C. The absence of F protein in SeV/ΔF and the additional mutations in M and HN in SeV/M
ts
HN
ts
ΔF probably weaken the ability to transport M protein to the plasma membrane, leading to the diminished formation of NTVLP.
Total lymphoid irradiation nonmyeloablative preconditioning enriches for IL-4–producing CD4+-TNK cells and skews differentiation of immunocompetent donor CD4+cells
Authors: Rigby Shawn M. , Rouse Todd , Field Elizabeth H.
Published: February 2003

Preconditioning with the nonmyeloablative regimen total lymphoid irradiation (TLI) before hematopoietic cell transplantation facilitates the establishment of mixed chimerism and protects against graft-versus-host disease. We reported that the development of mixed chimerism requires interleukin (IL)–4 and is associated with increased host anti-donor TH2 cells, but the effect of TLI on the differentiation of immunocompetent donor cells has not been investigated. To examine the extent to which TLI preconditioning influences donor T cells, we measured responses of transgenic CD4+ cells specific for ovalbumin peptide (OVA-Tg) following in vivo and in vitro antigen stimulation in a TLI-preconditioned environment. OVA-Tg cells that were adoptively transferred into TLI-preconditioned mice that express cross-reactive antigens produced more IL-4 and less interferon-γ and IL-2 than controls when stimulated with OVA peptide one week later. OVA-Tg primed in vitro with spleen from TLI-preconditioned mice generated more TH2 and fewer TH1 cells when stimulated in recall enzyme-linked immunosorbent spot (ELISPOT) assays with OVA peptide. Naive OVA-Tg up-regulated CD69 and CD25 normally following stimulation with OVA peptide in the presence of spleen from TLI-preconditioned mice, but proliferated less and secreted less IL-2 than controls. Surprisingly, naive OVA-Tg secreted IL-4 in primary cultures that were stimulated with OVA peptide in the presence of spleen from TLI-preconditioned mice. This response depends on CD4+ cells from TLI-spleen, which constitutively produce IL-4 and are composed primarily of CD4+–natural killer T (TNK) cells. Thus, TLI preconditioning enriches for IL-4–secreting and TNK-like CD4+ cells that may function in the protection from graft-versus-host disease by redirecting the differentiation of immunocompetent donor CD4+ cells toward TH2 and away from pathogenic TH1 cells.
Novel secreted isoform of adhesion molecule ICAM-4: potential regulator of membrane-associated ICAM-4 interactions
Authors: Lee Gloria , Spring Frances A. , Parsons Stephen F. , Mankelow Tosti J. , Peters Luanne L. , Koury Mark J. , Mohandas Narla , Anstee David J. , Chasis Joel Anne
Published: February 2003

Intercellular adhesion molecule-4 (ICAM-4), a newly characterized adhesion molecule, is expressed early in human erythropoiesis and functions as a ligand for binding α4β1 and αVintegrin-expressing cells. Within the bone marrow, erythroblasts surround central macrophages forming erythroblastic islands. Evidence suggests that these islands are highly specialized subcompartments where cell adhesion events, in concert with cytokines, play critical roles in regulating erythropoiesis and apoptosis. Since erythroblasts express α4β1 and ICAM-4 and macrophages exhibit αV, ICAM-4 is an attractive candidate for mediating cellular interactions within erythroblastic islands. To determine whether ICAM-4 binding properties are conserved across species, we first cloned and sequenced the murine homologue. The translated amino acid sequence showed 68% overall identity with human ICAM-4. Using recombinant murine ICAM-4 extracellular domains, we discovered that hematopoietic α4β1- expressing HEL cells and nonhematopoietic αV-expressing FLY cells adhered to mouse ICAM-4. Cell adhesion studies showed that FLY and HEL cells bound to mouse and human proteins with similar avidity. These data strongly suggest conservation of integrin-binding properties across species. Importantly, we characterized a novel second splice cDNA that would be predicted to encode an ICAM-4 isoform, lacking the membrane-spanning domain. Erythroblasts express both isoforms of ICAM-4. COS-7 cells transfected with green flourescent protein constructs of prototypic or novel ICAM-4 cDNA showed different cellular localization patterns. Moreover, analysis of tissue culture medium revealed that the novel ICAM-4 cDNA encodes a secreted protein. We postulate that secretion of this newly described isoform, ICAM-4S, may modulate binding of membrane-associated ICAM-4 and could thus play a critical regulatory role in erythroblast molecular attachments.
Dispersion effects in unreplicated factorial designs
Authors: Wiklander Kerstin , Holm Sture
Published: February 2003

Methods for estimation of dispersion effects in two‐level unreplicated factorial designs are studied. The consequences of non‐constant variance are discussed. A natural assumption concerning the form of the covariance of location effects leads to a particular normal model. Some linear combinations of the response variables are constructed in order to make a simple structure for inference. The precision of point estimators of dispersion effects, where one is based on experiments with replicates, are compared. A numerical example is given as an illustration of a test. Finally, estimations in fractional designs are described and discussed. Copyright © 2002 John Wiley & Sons, Ltd.
A simple method for nicardipine hydrochloride quantification in plasma using solid‐phase extraction and reversed‐phase high‐performance liquid chromatography
Authors: Fernandes Catarina Marques , Veiga Francisco José Baptista
Published: February 2003

A simple and sensitive reversed‐phase liquid chromatography method was developed and validated for the determination of nicardipine hydrochloride (NC) in rabbit plasma. Nicardipine hydrochloride and nimodipine, used as internal standard, were initially extracted from plasma by a rapid solid‐phase extraction using C18 cartridges. After extraction, nicardipine hydrochloride was separated by HPLC on a C18 column and quantified by ultraviolet detection at 254 nm. A mixture of acetonitrile–0.02 M sodium phosphate buffer–methanol (45:40:15) with 0.2% of triethylamine of pH of 6.1 was used as mobile phase. The mean (±SD) extraction efficiency of NC was 77.56 ± 5.4, 84.23 ± 4.32 and 83.94 ± 3.87% for drug concentrations of 5, 25 and 100 ng/mL, respectively. The method proved to be linear in the range of 5–100 ng/mL with a regression coefficient of 0.9993. The relative standard deviations of intra‐ and inter‐day analysis for NC in plasma were 3.26–6.52% (n = 5) and 4.71–9.38% (n = 5), respectively. The differences of the mean value measured from the concentration prepared, expressed in percentages (bias percentage), were only − 5.2, 0.4 and 0.8% at NC 5, 25 and 50 ng/mL, which confirmed the accuracy of the method. The analytical technique was used to determine NC plasma concentration after drug oral administration to rabbits. The results inferred that NC is rapidly absorbed in rabbits and has a short half‐life (t1/2 = 1.34 h). Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and Crystal Structure of IM‐6, a New Open Framework Cobalt–Gallium Phosphate with Ten‐ and Twelve‐Membered Pore Openings
Authors: Josien Ludovic , Simon‐Masseron Angélique , Gramlich Volker , Patarin Joël , Rouleau Loïc
Published: February 2003

A new three‐dimensional microporous cobalt–gallium phosphate, named IM‐6, has been synthesized under solvothermal conditions with an N‐substituted piperazine as organic template. The structure was solved by single‐crystal X‐ray diffraction (triclinic, P$\bar 1$, a=9.848(20), b=12.470(32), c=12.603(28) Å, α=63.47(16)°, β=74.56(16)°, γ=76.03(17)°). IM‐6 exhibits a new framework topology. The inorganic framework is built up of MO4 (M=Co, Ga) and PO4 tetrahedra. It displays a two‐dimensional interconnected channel system running along the [0 $\bar 1$ 1] and [1 0 0] directions and delimited by ten‐ and twelve‐membered ring openings, respectively.
Elektrisch leitfähige Kunststoffe: Der Weg zu einer neuen Materialklasse
Authors: Rehahn Matthias
Published: February 2003

Konventionelle gesättigte Polymere sind typische Isolatoren. Anders verhält es sich bei den konjugierten Polymeren: Liegen lange Ketten vor, die alternierend aus C‐C‐Doppel‐und C‐C‐Einfachbindungen bestehen, könnte es prinzipiell zu einer Delokalisierung der π‐Elektronen entlang des Polymerrückgrates kommen. Aufgrund der Peierls‐Instabilität ist dies aber nicht der Fall. Vielmehr bedarf es zusätzlich der Dotierung. Metallähnliche intrinsische Leitfähigkeit bei organischen Polymeren ist Ausgangspunkt für breite Anwendungen.
Electrochemical Approaches for Chemical and Biological Analysis on Mars
Authors: Kounaves Samuel P.
Published: February 2003

Obtaining in situ chemical data from planetary bodies such as Mars or Europa can present significant challenges. The one analytical technique that has many of the requisite characteristics to meet such a challenge is electroanalysis. Described here are three electroanalytical devices designed for in situ geochemical and biological analysis on Mars. The Mars Environmental Compatibility Assessment (MECA) was built and flight qualified for the now cancelled NASA Mars 2001 Lander. Part of MECA consisted of four “cells” containing arrays of electrochemical based sensors for measuring the ionic species in soil samples. A next‐generation MECA, the Robotic Chemical Analysis Laboratory (RCAL), uses a carousel‐type system to allow for greater customization of analytical procedures. A second instrument, proposed as part of the 2007 CryoScout mission, consists of a flow‐through inorganic chemical analyzer (MICA). CryoScout is a torpedo‐like device designed for subsurface investigation of the stratigraphic climate record embedded in Mars' north polar cap. As the CryoScout melts its way through the ice cap, MICA will collect and analyze the meltwater for a variety of inorganics and chemical parameters. By analyzing the chemistry locked in the layers of dust, salt, and ice, geologists will be able to determine the recent history of climate, water, and atmosphere on Mars and link it to the past. Finally, electroanalysis shows its abilities in the detection of possible microorganism on Mars or elsewhere in the solar system. To identify an unknown microorganism, one that may not even use Earth‐type biochemistry, requires a detection scheme which makes minimal assumptions and looks for the most general features. Recent work has demonstrated that the use of an array of electrochemical sensors which monitors the changes in a solution via electrical conductivity, pH, and ion selective electrodes, can be used to detect minute chemical perturbations caused by the growth of bacteria and with the correct methodology provide unambiguous detection of such life forms.
Voltammetric Exploration and Applications of Ultrasonic Cavitation
Authors: Banks Craig E. , Compton Richard G.
Published: February 2003

Voltammetric measurements carried out in the presence of power ultrasound are reviewed, and the physical processes responsible for the observed substantial augmentation of mass transport identified as resulting from a mixture of acoustic streaming and cavitation. The benefits conferred in electroanalysis or electrosynthesis of insonation simultaneous with electrolysis are summarised. The use of ultrafast (”nanosecond”) voltammetric measurements to probe the nature of the interfacial cavitational bubble dynamics is described and shown to provide information not readily accessed by other experiments. Lastly, voltammetry in acoustically emulsified (organic/aqueous) media is discussed. This has considerable ”green” potential for electrosynthesis, whilst the use of nanosecond voltammetry to probe the charge transferred as emulsion droplets impinge on the electrode allows a generic approach to the determination of the potential of zero charge of the latter.
Synthesis of 2‐monoglycerides by alcoholysis of palm oil and tuna oil using immobilized lipases
Authors: Wongsakul Sirirung , Prasertsan Poonsuk , Bornscheuer Uwe T. , H‐Kittikun Aran
Published: February 2003

Commercial immobilized lipases were used for the synthesis of 2‐monoglycerides (2‐MG) by alcoholysis of palm and tuna oils with ethanol in organic solvents. Several parameters were studied, i.e., the type of immobilized lipases, water activity, type of solvents and temperatures. The optimum conditions for alcoholysis of tuna oil were at a water activity of 0.43 and a temperature of 60 °C in methyl‐tert‐butyl ether for ∼12 h. Although immobilized lipase preparations from Pseudomonas sp. and Candida antarctica fraction B are not 1, 3‐regiospecific enzymes, they were considered to be more suitable for the production of 2‐MG by the alcoholysis of tuna oil than the 1, 3‐regiospecific lipases (Lipozyme RM IM from Rhizomucor miehei and lipase D from Rhizopus delemar). With Pseudomonas sp. lipase a yield of up to 81% 2‐MG containing 80% PUFA (poly‐unsaturated fatty acids) from tuna oil was achieved. The optimum conditions for alcoholysis of palm oil were similar as these of tuna oil alcoholysis. However, lipase D immobilized on Accurel EP100 was used as catalyst at 40 °C with shorter reaction times (<12 h). This lead to a yield of ∼60% 2‐MG containing 55.0‐55.7% oleic acid and 18.7‐21.0% linoleic acid.
Surface‐directed morphology evolution in ternary blends of polyethylene, polypropylene, and ethylene–propylene copolymer: A study by laser scanning confocal fluorescence microscopy
Authors: Moffitt Matthew , Rharbi Yahya , Tong Jiang‐Dong , Farhina J. P. S. , Li Huxi , Winnik M. A. , Zahalka H.
Published: February 2003

With laser scanning confocal fluorescence microscopy, we demonstrate a novel type of morphology evolution in moderately thick films (70–100 μm) of ternary blends of polypropylene (PP), polyethylene (PE), and ethylene–propylene rubber (EPR), in which EPR is labeled with a benzothioxanthene dye (HY‐EPR). The blends are prepared by solution blending, and the phase morphology evolves during the annealing of the blend films in a stainless steel mold. Our results indicate that wetting of the mold surface is a driving force in morphology evolution for the two blend compositions investigated. For 81/14/5 PP/PE/HY‐EPR, phase evolution within the mold results in a laminar structure and hydrodynamic channels, features which have previously been found in thin films of polymer blends as a result of surface‐directed spinodal decomposition. In a blend with a lower weight fraction of the dispersed phase (92/7/1 PP/PE/HY‐EPR), we find that the PE/HY‐EPR domains are larger and more polydisperse closer to the surface because of wetting of the mold wall. We also show that the phase morphology in these films can be controlled by the nature of one or both of the surfaces being varied. When one of the mold surfaces is replaced with a thin film of PP homopolymer, we observe draining of PE/HY‐EPR from the PP to the mold surface, which results in a bilayer structure. A trilayer morphology is likewise obtained by the replacement of both mold surfaces with PP. We also carry out three‐dimensional image reconstruction on a single PE/HY‐EPR particle within the 81/14/5 PP/PE/HY‐EPR blend to obtain detailed information on the interphase structure. We find that HY‐EPR of this composition (30/70 ethylene/propylene) fully coats the PE dispersed phase and partially penetrates the PE droplets. This result falls between the interphase structures found for previously investigated EPR compositions (40/60 and 80/20 ethylene/propylene). © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 637–654, 2003
Process diversity
Authors: Rus Ioana , Seaman Carolyn , Lindvall Mikael
Published: February 2003

Welcome to this special issue of the Journal of Software Maintenance and Evolution on process diversity. We, the guest editors, are very pleased to be able to include three fine papers on this subject, and we hope that our readers will find them stimulating and informative. Copyright © 2003 John Wiley & Sons, Ltd.
Vortex stretching driven by Jeffery‐Hamel flow
Authors: Zaturska M.B. , Banks W.H.H.
Published: February 2003

We present a new family of exact solutions of the Navier‐Stokes equations. The new flows, which result from vortex stretching, are generated by the well‐known class of Jeffery‐Hamel flows. These new solutions represent three‐dimensional flows and can be regarded as exact solutions or as perturbations of Jeffery‐Hamel flows. We also consider the effects of confining side‐walls on a particular Jeffery‐Hamel flow.
Visibility management in school and beyond: A qualitative study of gay, lesbian, bisexual youth
Authors: Lasser Jon , Tharinger Deborah
Published: February 2003

Grounded theory was utilized to develop a theory of gay, lesbian, and bisexual (GLB) youths’ interactions with and response to their environment. Data included in‐depth interviews of 20 GLB youth. The central phenomenon that emerged from the qualitative data analysis was the strategy ofvisibility management. Visibility management refers to the dynamic, ongoing process by which GLB youth make careful, planned decisions about whether they will disclose their sexual orientation, and, if they decide to disclose, to whom and how they disclose, and how they continue to monitor the presentation of their sexual orientation in different environments. The process of visibility management is proposed as a key construct in GLB identity development. Implications are proposed for working with GLB youth and their families and for making schools safer for GLB youth.
Oscillator strengths for S–S and S–D induced dipole transitions in alkali–rare gas systems
Authors: Pascale J.
Published: February 2003

Electronic oscillator strengths for induced dipole transitions in alkali–rare gas systems have been calculated as a function of internuclear distance using adiabatic potential energy curves and molecular wavefunctions previously obtained from a pseudopotential model. The molecular transitions considered are those associated, in the separated atom limit, with S–S and S–D electric dipole forbidden transitions in the alkali atom. The oscillator strengths are found to be relatively large (about 10−2–10−4) at small and intermediate internuclear distances (R∼3–12 a.u.).
Susceptibilities and electric and magnetic polarization fluctuations in nonoptically active media
Authors: Fulton Robert L.
Published: February 2003

The previous work which related electric polarization fluctuations to the dielectric constant is extended to include magnetic polarization fluctuations in nonoptically active media. To do this it is necessary to assume that electric fields induce changes only in the electric polarization and magnetic fields induce changes only in the magnetic polarization (in a well defined sense given in the text). This assumption is implemented after determining the relation between the average value of an arbitrary quantity and the average fields in the medium. The phenomenological parameters are related to the susceptibilities which, in turn, are related to the fluctuations by the Callen–Welton theorem. Finally, various approximate relations resulting from the neglect of certain specified electromagnetic interactions in the calculations of the susceptibilities are discussed.
Semiclassical theory of ’’optical rotation’’ in pure rotational spectroscopy
Authors: Salzman W. R.
Published: February 2003

The possibility of optical rotation in pure rotational spectroscopy is discussed. Expressions for the rotational strength of the J=0 →J=1 transition and transition rates for left- and right-circularly polarized light are derived.
Relaxation of the aspherical shapes of random-coil polymer chains
Authors: Kranbuehl David E. , Verdier Peter H.
Published: February 2003

The conformations of random-coil polymer chains are known to be appreciably more aspherical than might have been expected intuitively. However, this instantaneous asphericity will only affect the measured physical properties of flexible chains in solution if the relaxation of the asphericity requires a time longer than the inherent sampling time of the experiment. It is therefore important, in the analysis of phenomena which depend upon chain shape, to know the time scale over which deviations from spherical symmetry persist. In this paper we extend our previous work on the relaxation of asphericity in chains without excluded volume interactions and present corresponding results for chains with excluded volume. Autocorrelation functions for the radius of gyration squared, its principal components, and the moments of inertia are determined using a dynamical model for linear polymer chains which simulates excluded volume effects. The results suggest that the asphericity of a random-flight chain is increased by the introduction of excluded volume interactions, and that the segment distribution will appear spherically symmetric only when it is averaged over a time comparable with or longer than the longest times in the relaxation-time spectrum of the chain.
Reinvestigation of vibronic level dependence of fluorescence quantum yields and radiative and nonradiative lifetimes of p-difluorobenzene in its first excited singlet state (1B2u)
Authors: Volk Leonard J. , Lee Edward K. C.
Published: February 2003

The fluorescence quantum yields (Φf) of p-C6H4F2 (1B2u) have been measured for a number of vibronic levels at low pressures where ’’isolated’’ molecule condition can be maintained. Our present values obtained by continuous excitation are significantly different than those obtained previously by flash excitation [C. Guttman and S. A. Rice, J. Chem. Phys. 61, 661 (1974)]; we obtain 0.70 vs the previous value of 1.00 for the fluorescence quantum yield of the 0–0 band. On the basis of the new value of Φf, a set of revised values of radiative lifetimes (τr) and nonradiative lifetimes (τnr) of various vibronic levels are obtained.
Electronic spectrum and structure of the HSO radical
Authors: Schurath U. , Weber M. , Becker K. H.
Published: February 2003

A chemiluminescence spectrum in the range 5200–9600 Å is assigned to the 2A′–2Am’ transition of the HSO radical. The 0–0 band is observed at 6960 Å. The deuterated radical was also studied. The vibrational frequencies deduced from the vibronic transitions are ν′2(HSO) =828, ν″2(HSO) =1063, ν′2(DSO) =600±10, and ν″2(DSO) =770±10 for the bending vibration, and ν′3(HSO) =702±5 and ν″3(HSO) =1013±5 cm−1 for the SO bond stretch. The latter does not change significantly upon deuteration. The SH bond stretch ν1 is not manifested in the spectrum, and is assumed to come close to the SH group frequency of 2570 cm−1 in the electronic ground state. The frequency increases slightly upon excitation to the 2A′ state, as follows from the shift of the 0–0 band to 6958 cm−1 upon deuteration. Approximate bond lengths and angles of HSO in both electronic states are deduced from the partially resolved subband structure of the vibronic bands, which is compared with computed band contours. Relative Franck–Condon factors obtained from the intensities within the v″3 progressions are in accordance with an increase of the SO bond length from r″SO=1.54 to r′SO=1.69 Å. Emission from HSO (2A′) is observed up to v′3=7 in the system O/H2S/O3. Excitation is believed to occur through the chemiluminescent reaction SH+O3→SHO*+O2, leading to an upper limit of ΔH°f(HSO) ≲14.9 kcal/mole.
Infrared-active lattice vibrations in alkali azides
Authors: Massa N. E. , Mitra S. S. , Prask H. , Singh R. S. , Trevino S. F.
Published: February 2003

The far infrared reststrahlen spectra of lithium, sodium, potassium, rubidium, and cesium azides have been measured. The reflection spectra of monocrystalline and polycrystalline samples were analyzed by Kramers–Krönig and damped Lorentz oscillator methods to obtain long wavelength optical mode frequencies and optical constants. It has been determined that the substances are quasicubic, which results in small anisotropy splittings. The similarity of the alkali azides with corresponding halides is pointed out.
Magnetic dipole and electric quadrupole interactions in polarized light scattering from polymers
Authors: Harris Robert A. , McClain Wm. Martin
Published: February 2003

We generalize our previous work on the polarization analysis of light scattering from dilute polymer solutions to include the effect of magnetic dipole and electric quadrupole interactions of the monomer units with the light. We write out the elements of the Perrin matrix.
Quantum-dynamical model for thermal desorption of gases from solid surfaces
Authors: Garrison B. J. , Diestler D. J. , Adelman S. A.
Published: February 2003

The Montroll–Shuler model for the kinetics of dissociation of a diatomic molecule in a heat bath is adapted to thermal desorption of gases from solid surfaces. The rate constant kMS is compared with that predicted by transition-state theory, kTST, and that extracted from experimental data for the system Xe/W. A central feature of the present model is that kMS shows a strong explicit dependence (ϑ−3D in the Debye approximation) upon the lattice dynamics, whereas kTST has none at all.
Local mode involvement in the vibrational relaxation of isolated (O2)2 dimers
Authors: Goodman Julie , Brus L. E.
Published: February 2003

Study of five isotopic species of isolated (O2)2 dimer in solid neon host near 4.2 °K shows that the mechanism of 1Δg+1Δg excited state vibrational relaxation involves intersystem crossing into the 3Σ−g+1Σ+g state. Several reversible dynamic equilibria are observed between nearly degenerate 1Δg+1Δg and 3Σ−g+1Σ+g vibronic states. Indirect arguments suggest that the nearest neighbor, nonresonant vibrational energy transfer time from 16O2(1Δg) to 18O2(1Δg) is order-of-magnitude 10−9–10−10 s. Vibrational relaxation rates for (0+v) 3Σ−g+1Σ+g states (v?3) are slower with heavier reduced masses. The relaxation rate depends not only on the nuclei in the excited O2, but also on the nuclei in the unexcited nearest neighbor O2. These results are consistent with O2 rotation accepting energy during the vibrational relaxation process. This appears to be the first such observation for a nonhydride molecule in condensed phase. The relation between spectral polarization and rotation as the accepting mode is discussed.
Semiclassical theory of the effects of collisions between rotors on molecular spectral line shapes. I
Authors: Turfa Alexander F. , Fitz D. E. , Marcus R. A.
Published: February 2003

The semiclassical (WKB) limit of the quantum mechanical expression for the collisional line broadening cross section of the microwave spectrum of gaseous molecules is derived. For the present purpose of considering binary collisions between such species as OCS and CO2, action-angle-like variables for the classical mechanics of two interacting rotors are developed. Applications can be made to the evaluation of T2 (microwave line broadening) and T1 (microwave transient experiments) cross sections and to calculations of rotational and vibrational energy transfer for linear molecule–linear molecule systems.
The computation of intermolecular forces with Gaussian basis functions. Illustration with He2
Authors: Burton Peter G.
Published: February 2003

A new and effective technique for basis set augmentation within correlated wavefunction computations of intermolecular forces is illustrated. The technique involves reducing or buffering the ’’ghost orbital’’ basis set borrowing by one species of the functions of a neighboring species when the basis set used to describe each species is not complete. This is achieved by employing a small set of Gaussians (s and higher angular momentum types) moved off the nuclei into the internuclear region. Provided these small sets are carried with each species as the interspecies distance is varied, reliable interspecies potential curves may be obtained. An illustrative application to He2 is described.
Methods for optical detection of electron spin coherence in nonphosphorescent triplet states
Authors: Brenner Henry C.
Published: February 2003

A method is described whereby the time development of the coherent components within the spin sublevels of an excited triplet state can be monitored, using an observable which can measure only the total population of the sublevel manifold, such as absorbance to higher triplet states or singlet fluorescence. The approach is very similar to the ’’probe’’ pulse method recently developed for the optical detection of electron spin coherence in phosphorescent triplet states, but the procedure for extracting the value of the coherent component is different. In the present approach it is shown that the recovery of the total population of the sublevel manifold to steady state, after the pulse sequence has been applied, is sensitive to the coherence. By measuring the amplitude of the recovery curve as a function of pulse timing the lifetime of the coherent component can be obtained. Application of the method to some common coherence experiments is discussed.
Absolute coverage determination of CO on nickel crystal faces: Papers by Erley, Besocke, and Wagner [J. Chem. Phys. 66, 5269 (1977)] and by Klier, Zettlemoyer, and Leidheiser [J. Chem. Phys. 52, 589 (1970)]
Authors: Klier K. , Zettlemoyer A. C. , Leidheiser H.
Published: February 2003

JCPSA,52,589,1970
A crossed molecular beam study of the translational energy dependence of Cl+Br2→BrCl+Br reaction
Authors: Valentini James J. , Lee Yuan T. , Auerbach Daniel J.
Published: February 2003

A crossed molecular beam study of the Cl+Br2→BrCl+Br reaction using supersonic nozzle beams of Cl and Br2 has been carried out at collision energies of 6.8, 14.7, and 17.7 kcal/mole. At all three collision energies the BrCl product is quite strongly forward peaked, with a large fraction (80%–85%) of the energy in internal degrees of freedom. The results of the experiment indicate that the Cl+Br2 reaction displays the characteristics of an exoergic reaction on an attractive surface with early energy release. Estimated total cross sections at 6.8 and 14.7 kcal/mole are 11 Å and 14 Å2, respectively.
Bimodal distribution of BaI vibrational states from the reaction Ba+CF3I
Authors: Smith G. P. , Whitehead J. C. , Zare R. N.
Published: February 2003

Unrelaxed vibrational state distributions of BaI product are reported for the reaction Ba+CF3I→BaI+CF3, using laser-induced fluorescence. Product state distributions were measured using a beam–gas arrangement and a primitive angular distribution was also determined using a crossed-beam configuration. The BaI vibrational distribution is bimodal with a low vibrational component peaking at v∼27 and a high vibrational component peaking at v∼47. At least 75% of the BaI is produced in the high vibrational levels. The angular distribution indicates that the BaI formed in the high vibrational states is scattered in a forward direction with respect to the Ba beam, but the low vibrational component is not sharply forward scattered. The Ba+CF3I reaction is thought to proceed by two mechanisms: (1) attack in the direction of I–CF3, leading to BaI product formation with low vibrational energy; and (2) attack in the direction of CF3–I, either by initial attack of the CF3 end followed by migration or by attack of the I end at large impact parameters, leading to BaI product formation with high vibrational energy.
Raman intensities of single crystal ice I
h
Authors: Scherer James R. , Snyder Robert G.
Published: February 2003

Raman intensities of single crystal H2O, D2O and HOD ice Ih were measured from −4 to −150°C. The cc, aa, ca, aa′ (c is the unique axis) polarizability components were measured from 20 to 4000 cm−1. Shoulders are observed on the high frequency side of the νOH and νOD bands of HOD which we attribute to combination bands between νOH and νOD and lattice modes. Intensities in the OH stretching region are interpreted using bond polarizability theory. The ratio of anistropy to mean polarizability for the OH bond was found to be 1.81. The analysis of the intensities suggests that those hydrogen bonds that statistically parallel to the c axis are slightly more linear than those that are equatorial to the c axis. The effects of intermolecular coupling of OH stretching vibrations are very evident in the spectra. However, it appears that such coupling is not the principal cause of the breadth of the isotropic part of the symmetric OH stretch band at −4°C. Evidence is presented that indicates extensive coupling of librational modes. Comparisons are made between the spectra of ice at −4°C, liquid water, and amorphous ice.
Carbon isotope separation by multiphoton dissociation of CF3I
Authors: Bittenson S. , Houston P. L.
Published: February 2003

A selective multiphoton dissociation process has been used to enrich carbon-13 in CF3I. A separation factor of nearly 600 has been achieved for irradiation of 0.1 torr of CF3I at -80 °C with the R (14) line of the 9.6 μ CO2 laser transition. An investigation of the dependence of the enrichment factor on pressure indicates that collisions during the dissociation are effective in destroying the selectivity. The multiphoton dissociation is quite efficient. At laser energy fluences of 1.2 J/cm2, one in every 11 absorbed photons contributes its energy to the breaking of the C–I bond.
High pressure optical studies of anils and related compounds dissolved in polystyrene
Authors: Hockert E. N. , Drickamer H. G.
Published: February 2003

High pressure optical studies have been made on thermochromic and photochromic anils and related compounds dissolved in polystyrene (PS). None of the compounds exhibited thermochromism at a concentration of 0.03 mole/liter, but at 0.3 mole/liter 5-BrSA showed a very definite thermochromic yield quite possibly due to clusters or aggregates. These aggregates exhibited a volume change of −1.65 cc/mole for the transformation in comparison to −1.2 cc/mole in the crystal. All the anils exhibited photochromism in PS. For 5-BrSA the conversion rate showed a maximum with pressure at 25 °C but a monotonic decrease in conversion at −75 °C. SA exhibits a maximum in conversion rate with pressure at 25°C and −75°C but not at −140°C. The results can be explained in terms of the same processes which occur in the crystal but with a considerably increased rate of the thermal back reaction. The emission intensities exhibited a maximum with increasing pressure, which results from the same balancing between the nonradiative rate and rate of occupation of the emitting state as occurred in the crystal.
Ground and excited state dipole moments of all-t
r
a
n
s-retinal and all-t
r
a
n
s-retinylidene-n-butylamine in solution
Authors: Corsetti James P. , Kohler Bryan E.
Published: February 2003

Ground state dipole moments of all-trans-retinal and all-trans-retinylidene–n-butylamine have been determined by dielectric constant measurements of dilute hexane solutions. Excited state dipole moments for the intense low energy absorption band have been estimated from the ground state moments and an analysis of the solvent shifts of absorption spectra using a corrected solvent shift theory. The ground state moments of all-trans-retinal and the n-butylamine Schiff’s base were found to be 4.6 and 2.1 D, respectively. The corresponding excited state moments are approximately 6 and 5 D.
Study of adsorbed water: Electric potential calculation and molecular orientation in the two layer hydrate of a Mg vermiculite
Authors: Hougardy J. P. , Tougne P. , Bonnin D. , Legrand A. P.
Published: February 2003

The electric potential in two-layer hydrate Llano and Kenya Mg vermiculite is calculated using the Ewald method, and is applied to the interpretation of the NMR spectra of protons of the water molecules of the interlamellar space.
Collisional deactivation of laser excited singlet molecular oxygen by ozone
Authors: Parker J. G.
Published: February 2003

The effect of small amounts of ozone (5–38 mm) on the rate of collisional deactivation of singlet molecular oxygen O2(1Δg) excited by means of laser radiation at 1.064 μ has been investigated. Due to the fact that high oxygen pressures were used (35 atm), the rate of deactivation of O2(1Δg) by collision with ground electronic state oxygen O2(3Σ−g) competes with deactivation by O3, a situation not encountered by previous investigators at much lower pressures. In the case of minimum O3 partial pressure (5 mm), the effect of O3 in direct deactivation of O2(1Δg) is negligible, with the controlling process being an intersystem crossing (electronic–vibration) O2(1Δg)(v′=0) →O2(3Σ−g)(v=5). Analysis of the data indicates that transfer of this large amount of vibrational energy to O3 en bloc must take place with high efficiency, producing O3 in a highly excited vibrational state lying just below the dissociation limit. Dependence of the overall deactivation rate of O2(1Δg) on O3 partial pressure exhibits a quadratic term in addition to the linear variation observed by other investigators at lower pressures. The effect of adding a third component (He, SO2, CO2, and NO2) with the ozone partial pressure held constant was also studied.
Predictions of infrared intensities for some halogen pentafluoride molecules
Authors: Krohn Burton J. , Person Willis B. , Overend John
Published: February 2003

The infrared intensities (and wavenumbers) for the fundamental vibrations of ClF5, BrF5, and IF5 have been predicted, using an atomic polar tensor for the F atom transferred from the CH3F molecule, together with matrices obtained from the normal coordinate analysis of each molecule. The procedure used in these predictions has been described previously in detail for the prediction of infrared intensities of SF6 and UF6. Comparison of the calculated intensities with the experimental spectra of XF5 molecules reveals that the predicted values are in fairly good agreement with the experimental values. The model and procedure allow prediction of intensities of binary combination and overtone bands as well as fundamental vibrations. The comparison between prediction and experiment is presented in some detail, and some reasons for the (relatively few) apparent discrepancies are discussed.