bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface‐enhanced Raman difference between bombesin and its modified analogues on the colloidal and electrochemically roughen silver surfaces
Authors: Podstawka Edyta , Ozaki Yukihiro
Published: May 2008

In this article, surface‐enhanced Raman scattering (SERS) spectra of bombesin (BN) and its six modified analogues ([D‐Phe12]BN, [Tyr4]BN, [Tyr4,D‐Phe12]BN, [D‐Phe12,Leu14]BN, [Leu13‐®‐Leu14]BN, and [Lys3]BN) on a colloidal silver surface are reported and compared with SERS spectra of these species immobilized onto an ellectrochemically roughen silver electrode. Changes in enhancement and wavenumber of proper bands upon adsorption on different silver surfaces are consistent with BN and its analogues adsorption primarily through Trp8. Slightly different adsorption states of these molecules are observed depending upon natural amino acids substitution. For example, the indole ring in all the peptides interacts with silver nanoparticles in a edge‐on orientation. It is additionally coordinated to the silver through the N1H bond for all the peptides, except [Phe12]BN. This is in contrary to the results obtained for the silver roughen electrode that show direct but not strong N1H/Ag interaction for all peptides except [D‐Phe12,Leu14]BN and [Leu13‐®‐Leu14]BN. For BN only CO is not involved in the chemical coordination with the colloidal surface. [Lys3]BN and BN also adsorb with the CN bond of NH2 group normal and horizontal, respectively, to the colloidal surface, whereas CNH2 in other peptides is tilted to this surface. Also, the Trp8 CH2 moiety of only [Tyr4]BN, [Lys3]BN, and [Tyr4,D‐Phe12]BN coordinates to Ag, whereas the Phe12 ring of [Phe12]BN, [Tyr4,D‐Phe12]BN, and [D‐Phe12,Leu14]BN assists in the peptides binding only on the colloidal silver. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 807–819, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
NMR structure of biosynthetic engineered human insulin monomer B31Lys‐B32Arg in water/acetonitrile solution. Comparison with the solution structure of native human insulin monomer
Authors: Bocian Wojciech , Borowicz Piotr , Mikołajczyk Jerzy , Sitkowski Jerzy , Tarnowska Anna , Bednarek Elżbieta , Głąbski Tadeusz , Tejchman‐Małecka Bożena , Bogiel Monika , Kozerski Lech
Published: May 2008

A solution NMR‐derived structure of a new long ‐acting, B31Lys‐B32Arg (LysArg), engineered human insulin monomer, in H2O/CD3CN, 65/35 vol %, pH 3.6, is presented and compared with the available X‐ray structure of a monomer that forms part of a hexamer (Smith, et al., Acta Crystallogr D 2003, 59, 474) and with NMR structure of human insulin in the same solvent (Bocian, et al., J Biomol NMR 2008, 40, 55–64). Detailed analysis using PFGSE NMR (Pulsed Field Gradient Spin Echo NMR) in dilution experiments and CSI analysis prove that the structure is monomeric in the concentration range 0.1–3 mM. The presence of long‐range interstrand NOEs in a studied structure, relevant to the distances found in the crystal structure of the monomer, provides the evidence for conservation of the tertiary structure. Therefore the results suggest that this solvent system is a suitable medium for studying the native conformation of the protein, especially in situations (as found for insulins) in which extensive aggregation renders structure elucidations in water difficult or impossible. Starting from the structures calculated by the program CYANA, two different molecular dynamics (MD) simulated annealing refinement protocols were applied, either using the program AMBER in vacuum (AMBER_VC), or including a generalized Born solvent model (AMBER_GB). Here we present another independent evidence to the one presented recently by us (Bocian et al., J Biomol NMR 2008, 40, 55–64), that in water/acetonitrile solvent detailed structural and dynamic information can be obtained for important proteins that are naturally present as oligomers under native conditions. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 820–830, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Complexation of β‐lactam antibiotic drug carbenicillin to bovine serum albumin: Energetics and conformational studies
Authors: Thoppil Anu A. , Sharma Ruchika , Kishore Nand
Published: May 2008

Binding of the antibiotic drug carbenicillin to bovine serum albumin (BSA) has been studied using isothermal titration calorimetry (ITC) in combination with fluorescence and circular dichroism (CD) spectroscopies. The thermodynamic parameters of binding have been evaluated as a function of temperature, ionic strength, and in the presence of anionic, cationic and nonionic surfactants, tetrabutylammonium bromide, and sucrose. The values of van't Hoff enthalpy do not agree with the calorimetric enthalpy indicating conformational changes in the protein upon drug binding. These observations are supported by the intrinsic fluorescence and CD spectroscopic measurements. A reduction in the binding affinity of carbenicillin to BSA is observed with increase in ionic strength of the solution, thereby suggesting, prevailing of electrostatic interactions in the binding process. The involvement of hydrophobic interactions in the binding of the drug to the protein is also indicated by a slight reduction in binding constant in the presence of tetrabutylammonium bromide. The experiments in the presence of sucrose suggest that hydrogen bonding is perhaps not dominant in the binding. The anionic surfactant sodium dodecyl sulphate (SDS) is observed to completely interfere in the ionic interactions in addition to its partial denaturing capacity. However, the presence of cationic surfactant hexadecyl trimethylammonium bromide (HTAB) and nonionic surfactant Triton‐X 100 induce a slight reduction in the values of binding affinity. These calorimetric and spectroscopic results, provide quantitative information on the binding of carbenicillin to BSA and suggests that the binding is dominated by electrostatic interactions with contribution from hydrophobic interactions. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 831–840, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Determination of the secondary structure of proteins in different environments by FTIR‐ATR spectroscopy and PLS regression
Authors: Wang Yeqiu , Boysen Reinhard I. , Wood Bayden R. , Kansiz Mustafa , McNaughton Don , Hearn Milton T. W.
Published: May 2008

The secondary structures of proteins (α‐helical, β‐sheet, β‐turn, and random coil) in the solid state and when bound to polymer beads, containing immobilized phenyl and butyl ligands such as those as commonly employed in hydrophobic interaction chromatography, have been investigated using FTIR‐ATR spectroscopy and partial least squares (PLS) methods. Proteins with known structural features were used as models, including 12 proteins in the solid state and 7 proteins adsorbed onto the hydrophobic surfaces. A strong PLS correlation was achieved between predictions derived from the experimental data for 4 proteins adsorbed onto the phenyl‐modified beads and reference data obtained from the X‐ray crystallographic structures with r2 values of 0.9974, 0.9864, 0.9924, and 0.9743 for α‐helical, β‐sheet, β‐turn, and random coiled structures, respectively. On the other hand, proteins adsorbed onto the butyl sorbent underwent greater secondary structural changes compared to the phenyl sorbent as evidenced from the poorer PLS r2 values (r2 are 0.9658, 0.9106, 0.9571, and 0.9340). The results thus indicate that the secondary structures for these proteins were more affected by the butyl sorbent, whereas the secondary structure remains relatively unchanged for the proteins adsorbed onto the phenyl sorbent. This study has important ramifications for understanding the nature of protein secondary structural changes following adsorption onto hydrophobic sorbent surfaces. This knowledge could also enable the development of useful protocols for enhancing the chromatographic purification of proteins in their native bioactive states. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 895–905, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Differences in residual lignin properties between Betula verrucosa and Eucalyptus urograndis kraft pulps
Authors: Hänninen Tuomas A. , Kontturi Eero , Isogai Akira , Vuorinen Tapani
Published: May 2008

By comparing the ultrastructural features of two oxygen delignified hardwood kraft pulps (Eucalyptus urograndis and Betula verrucosa), we have demonstrated a marked difference in their residual lignin properties. In this study, properties such as crystallinity and crystal size of cellulose, molecular weights, carboxyl group contents, and carbohydrate compositions of the two kraft pulps were compared. The examined pulps were in our observations relatively similar. A significant difference, however, was observed in the size exclusion chromatography measurements, which indirectly suggested that a significant portion of residual lignin in eucalyptus pulp was associated with cellulose. Birch pulp, in contrast, exhibited a more conventional tendency for hardwood pulps: lignin mainly associated with hemicelluloses. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 889–893, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Extracellular Synthesis of Crystalline Silver Nanoparticles and Molecular Evidence of Silver Resistance from Morganella sp.: Towards Understanding Biochemical Synthesis Mechanism
Authors: Parikh Rasesh Y. , Singh Sanjay , Prasad B. L. V. , Patole Milind S. , Sastry Murali , Shouche Yogesh S.
Published: May 2008

There has been significant progress in the biological synthesis of nanomaterials. However, the molecular mechanism of synthesis of such bio‐nanomaterials remains largely unknown. Here, we report the extracellular synthesis of crystalline silver nanoparticles (AgNPs) by using Morganella sp., and show molecular evidence of silver resistance by elucidating the synthesis mechanism. The AgNPs were 20±5 nm in diameter and were highly stable at room temperature. The kinetics of AgNPs formation was investigated. Detectable particles were formed after an hour of reaction, and their production remained exponential up to 18 h, and saturated at 24 h. Morganella sp. was found to be highly resistant to silver cations and was able to grow in the presence of more than 0.5 mM AgNO3. Three gene homologues viz. silE, silP and silS were identified in silver‐resistant Morganella sp. The homologue of silE from Morganella sp. showed 99 % nucleotide sequence similarity with the previously reported gene, silE, which encodes a periplasmic silver‐binding protein. The homologues of silP and silS were also highly similar to previously reported sequences. Similar activity was totally absent in closely related Escherichia coli; this suggests that a unique mechanism of extracellular AgNPs synthesis is associated with silver‐resistant Morganella sp. The molecular mechanism of silver resistance and its gene products might have a key role to play in the overall synthesis process of AgNPs by Morganella sp. An understanding of such biochemical mechanisms at the molecular level might help in developing an ecologically friendly and cost‐effective protocol for microbial AgNPs synthesis.
Real‐Time Amperometric Analysis of Reactive Oxygen and Nitrogen Species Released by Single Immunostimulated Macrophages
Authors: Amatore Christian , Arbault Stéphane , Bouton Cécile , Drapier Jean‐Claude , Ghandour Hala , Koh Alaric C. W.
Published: May 2008

Macrophages are key cells of the immune system. Immunologically activated macrophages are known to release a cocktail of reactive oxygen and nitrogen species. In this work, RAW 264.7 macrophages were activated by interferon‐γ and lipopolysaccharide, and the reactive mixture released by single cells was analyzed, in real time, by amperometry at platinized carbon microelectrodes. In comparison with untreated macrophages, significant increases in amperometric responses were observed for activated macrophages. Nitric oxide (NO.), nitrite (NO2−), and peroxynitrite (ONOO−) were the main reactive species detected. The amounts of these reactive species were quantified, and their average fluxes released by a single, activated macrophage were evaluated. The detection of ONOO− is of particular interest, as its role and implications in various physiological conditions have been widely debated. Herein, direct evidence for the formation of ONOO− in stimulated macrophages is presented. Finally, the presence of 1400W, a selective inducible nitric oxide synthase (iNOS) inhibitor, led to an almost complete attenuation of the amperometric response of activated RAW 264.7 cells. The majority of the reactive species released by a macrophage are thus likely to be derived from NO. and superoxide (O2.−) co‐produced by iNOS.
A β‐1,4‐Galactosyltransferase from Helicobacter pylori is an Efficient and Versatile Biocatalyst Displaying a Novel Activity for Thioglycoside Synthesis
Authors: Namdjou Darius‐Jean , Chen Hong‐Ming , Vinogradov Evguenii , Brochu Denis , Withers Stephen G. , Wakarchuk Warren W.
Published: May 2008

Helicobacter pylori is a highly persistent and common pathogen in humans. It is the causative agent of chronic gastritis and its further stages. HP0826 is the β‐1,4‐galactosyltransferase involved in the biosynthesis of the LPS O‐chain backbone of H. pylori. Though it was first cloned nearly a decade ago, there are surprisingly limited data about the characteristics of HP0826, especially given its prominent role in H. pylori pathogenicity. We here demonstrate that HP0826 is a highly efficient and promiscuous biocatalyst. We have exploited two novel enzymatic activities for the quantitative synthesis of the thiodisaccharide Gal‐β‐S‐1,4‐GlcNAc‐pNP as well as Gal‐β‐1,4‐Man‐pNP. We further show that Neisseria meningitidis β‐1,4‐galactosyltransferases LgtB can be used as an equally efficient catalyst in the latter reaction. Thiodisaccharides have been extensively used in structural biology but can also have therapeutic uses. The Gal‐β‐1,4‐Man linkage is found in the Leishmania species LPG backbone disaccharide repeats and cap, which have been associated with vector binding in Leishmaniasis.
Synthesis and Characterization of a Grapevine Nanostructure Consisting of Single‐Walled Carbon Nanotubes with Covalently Attached [60]Fullerene Balls
Authors: Wu Wei , Zhu Huarui , Fan Louzhen , Yang Shihe
Published: May 2008

A grapevine nanostructure based on single‐walled carbon nanotubes (SWNTs) covalently functionalized with [60]fullerene (C60) has been synthesized and characterized in detail. Investigations into the ball‐on‐tube carbon nanostructure by ESR spectroscopy indicate a tendency for ground‐state electron transfer from the SWNT to the C60 moieties. The cyclic‐voltammetric response of the nanostructure film exhibits reversible multiple‐step electrochemical reactions of the dispersed C60, which are strikingly similar to those of the C60 derivatives in solution, but with consistent negative shifts in the redox potential. This results from the covalent linkage of C60 to the surfaces of the SWNTs in the form of monomers and manifests the electronic interaction between the C60 and SWNT moieties.
Coupling Sol–Gel Synthesis and Microwave‐Assisted Techniques: A New Route from Amorphous to Crystalline High‐Surface‐Area Aluminium Fluoride
Authors: Dambournet Damien , Eltanamy Gehan , Vimont Alexandre , Lavalley Jean‐Claude , Goupil Jean‐Michel , Demourgues Alain , Durand Etienne , Majimel Jérôme , Rudiger Stephan , Kemnitz Erhard , Winfield John M. , Tressaud Alain
Published: May 2008

A non‐aqueous sol–gel Al‐based fluoride has been subjected to the microwave solvothermal process. The final material depends on the temperature heat treatment used. Three types of material have been prepared: 1) for low temperature heat treatment (90 °C) X‐ray amorphous alkoxy fluoride was obtained; 2) for the highest temperature used (200 °C) the metastable form β‐AlF3 was obtained with a very large surface area of 125 m2 g−1. The mechanism of the amorphous⇄crystalline transformation has been rationalised by the occurrence of a decomposition reaction of the gel fluoride induced by the microwave irradiation. 3) Finally, at intermediate temperature (180 °C) a multi‐component material mixture exhibiting a huge surface area of 525 m2 g−1 has been obtained and further investigated after mild post‐treatment fluorination using F2 gas. The resulting aluminium‐based fluoride still possesses a high‐surface‐area of 330 m2 g−1. HRTEM revealed that the solid is built from large particles (50 nm) identified as α‐AlF3, and small ones (10 nm), relative to an unidentified phase. This new high‐surface‐area material exhibits strong Lewis acidity as revealed by pyridine adsorption and catalytic tests. By comparison with other materials, it has been shown that whatever the composition/structure of the Al‐based fluoride materials, the number of strong Lewis acid sites is related to the surface area, highlighting the role of surface reconstruction occurring on a nanoscopic scale on the formation of the strongest Lewis acid sites.
Understanding Chemical Reactivity: The Case for Atom, Proton and Methyl Transfers
Authors: Arnaut Luis G. , Formosinho Sebastião J.
Published: May 2008

The concept of “chemical reactivity” assumes that atoms and molecules contain the necessary information to describe their evolution over time as they transform from reactants to products. This concept was useful in the past to rationalize reactivity trends and predict the behavior of new systems. Free‐energy relationships have played a central role in this field. However, electronic effects often counter the energetic effects and give rise to “anomalies” or separate correlations. We discuss a quantification of the concept of “chemical reactivity”, emphasizing the role of molecular and electronic factors in Chemistry.
The Importance of the Long Type 1 Copper‐Binding Loop of Nitrite Reductase for Structure and Function
Authors: Sato Katsuko , Firbank Susan J. , Li Chan , Banfield Mark J. , Dennison Christopher
Published: May 2008

The long 15‐residue type 1 copper‐binding loop of nitrite reductase has been replaced with that from the cupredoxin amicyanin (7 residues). This sizable loop contraction does not have a significant effect on the spectroscopy, and therefore, the structures of both the type 1 and type 2 CuII sites. The crystal structure of this variant with ZnII at both the type 1 and type 2 sites has been determined. The coordination geometry of the type 2 site is almost identical to that found in the wild‐type protein. However, the structure of the type 1 centre changes significantly upon metal substitution, which is an unusual feature for this class of site. The positions of most of the coordinating residues are altered of which the largest difference was observed for the coordinating His residue in the centre of the mutated loop. This ligand moves away from the active site, which results in a more open metal centre with a coordinating water molecule. Flexibility has been introduced into this region of the protein. The 200 mV increase in the reduction potential of the type 1 copper site indicates that structural changes upon reduction must stabilise the cuprous form. The resulting unfavourable driving force for electron transfer between the two copper sites, and an increased reorganisation energy for the type 1 centre, contribute to the loop variant having very little nitrite reductase activity. The extended type 1 copper‐binding loop of this enzyme makes a number of interactions that are important for maintaining quaternary structure.
Designed Peptides with Homochiral and Heterochiral Diproline Templates as Conformational Constraints
Authors: Chatterjee Bhaswati , Saha Indranil , Raghothama Srinivasarao , Aravinda Subrayashastry , Rai Rajkishor , Shamala Narayanaswamy , Balaram Padmanabhan
Published: May 2008

Diproline segments have been advanced as templates for nucleation of folded structure in designed peptides. The conformational space available to homochiral and heterochiral diproline segments has been probed by crystallographic and NMR studies on model peptides containing L‐Pro‐L‐Pro and D‐Pro‐L‐Pro units. Four distinct classes of model peptides have been investigated: a) isolated D‐Pro‐L‐Pro segments which form type II′ β‐turn; b) D‐Pro‐L‐Pro‐L‐Xxx sequences which form type II′‐I (βII′‐I, consecutive β‐turns) turns; c) D‐Pro‐L‐Pro‐D‐Xxx sequences; d) L‐Pro‐L‐Pro‐L‐Xxx sequences. A total of 17 peptide crystal structures containing diproline segments are reported. Peptides of the type Piv‐D‐Pro‐L‐Pro‐L‐Xxx‐NHMe are conformationally homogeneous, adopting consecutive β‐turn conformations. Peptides in the series Piv‐D‐Pro‐L‐Pro‐D‐Xxx‐NHMe and Piv‐L‐Pro‐L‐Pro‐L‐Xxx‐NHMe, display a heterogeneity of structures in crystals. A type VIa β‐turn conformation is characterized in Piv‐L‐Pro‐L‐Pro‐L‐Phe‐OMe (18), while an example of a 5→1 hydrogen bonded α‐turn is observed in crystals of Piv‐D‐Pro‐L‐Pro‐D‐Ala‐NHMe (11). An analysis of pyrrolidine conformations suggests a preferred proline puckering geometry is favored only in the case of heterochiral diproline segments. Solution NMR studies, reveal a strong conformational influence of the C‐terminal Xxx residues on the structures of diproline segments. In L‐Pro‐L‐Pro‐L‐Xxx sequences, the Xxx residues strongly determine the population of Pro‐Pro cis conformers, with an overwhelming population of the trans form in L‐Xxx = L‐Ala (19).
Syntheses, Reactivity and DFT Studies of Group 2 and Group 12 Metal Complexes of Tris(pyrazolyl)methanides Featuring “Free” Pyramidal Carbanions
Authors: Bigmore Helen R. , Meyer Jens , Krummenacher Ivo , Rüegger Heinz , Clot Eric , Mountford Philip , Breher Frank
Published: May 2008

Reactions of HC(Me2pz)3 with Grignard reagents, dialkyl magnesium compounds and dimethylzinc are reported, together with a DFT study on some of the aspects of this chemistry. Reactions of HC(Me2pz)3 with MeMgX (X=Cl or Br) gave the half‐sandwich zwitterionic compounds [Mg(MeTpmd)X] (X=Cl (2) or Br (3); MeTpmd−=[C(Me2pz)3]−). Addition of HCl to 2 gave the structurally characterised half‐sandwich compound [Mg{HC(Me2pz)3}Cl2(thf)] (4). The zwitterionic sandwich compound [Mg(MeTpmd)2] (5) formed in low yields in the reaction of MeMgX with HC(Me2pz)3 but was readily prepared from HC(Me2pz)3 and either MgnBu2 or MgPh2. The structurally characterised compound 5 contains two “naked” sp3‐hybridised carbanions fully separated from the dicationic metal centre. Only by using MgPh2 as starting material could the half‐sandwich compound [Mg(MeTpmd)Ph(thf)] (6) be isolated. The zwitterionic sandwich compound 5 reacted with HOTf (OTf−=[O3SCF3]−) to form the dication [Mg{HC(Me2pz)3}2]2+ (72+), which was structurally characterised. Pulsed field gradient spin‐echo (PGSE) diffusion NMR spectroscopy revealed both compounds to be intact in solution. In contrast to the magnesium counterparts, HC(Me2pz)3 reacted only slowly with ZnMe2 (and not at all with ZnPh2) to form the half‐sandwich zwitterion [Zn(MeTpmd)Me] (8), which contains a cationic methylzinc moiety separated from a single sp3‐hybridised carbanion. Density functional calculations on the zwitterions [M(MeTpmd)Me] and [M(MeTpmd)2] (M=Mg, Zn) revealed that the HOMO in each case is a MeTpmd‐based carbanion lone pair. The κ1C isomers of [M(MeTpmd)Me] were calculated to be considerably less stable than their κ3N‐bound counterparts, with the largest gain in energy for Mg due to the greater ease of electron transfer from metal to the MeTpmd apical carbon atom on formation of the zwitterion. Moreover, the computed MC bond dissociation enthalpies of the κ1C isomers of [M(MeTpmd)Me] are considerably higher than expected by simple extrapolation from the corresponding computed HC bond dissociation enthalpy.
Highly Effective and Reversible Control of the Rocking Rates of Rotaxanes by Changes to the Size of Stimulus‐Responsive Ring Components
Authors: Hirose Keiji , Ishibashi Kazuaki , Shiba Yoshinobu , Doi Yasuko , Tobe Yoshito
Published: May 2008

We have designed and synthesized rotaxanes whose rates of rocking motion (pendular motion) were switched reversibly through changes to the size of the ring component in response to external stimuli. The ring molecules of the rotaxanes incorporate a metaphenylene unit, which swings like a pendulum, and a dianthrylethane unit, which undergoes reversible isomerization in response to photo‐ and thermal stimuli and changes the size of the ring component. The rocking rates were estimated quantitatively by variable‐temperature (VT) NMR spectroscopy and saturation transfer experiments, which revealed substantial changes in the rates between the open and closed forms, particularly in the case of rotaxanes with an isopropoxy group attached to a phenylene unit.
The Elusive Structure of CrCl2—A Combined Computational and Gas‐Phase Electron‐Diffraction Study
Authors: Vest Brian , Varga Zoltán , Hargittai Magdolna , Hermann Andreas , Schwerdtfeger Peter
Published: May 2008

Chromium dichloride poses a challenge to the structural chemist. Its different forms of aggregation and association display all well‐known structural distortions induced by vibronic interactions. The monomeric molecule has a Renner–Teller distorted bent geometry, the crystal exhibits strong Jahn–Teller distortion, and the oligomers have slightly distorted four‐membered‐ring structures due to the pseudo‐Jahn–Teller effect. In this paper we report on the low‐energy structures of the monomer and its clusters, Cr2Cl4, Cr3Cl6, and Cr4Cl8, from unrestricted Kohn–Sham (broken‐symmetry) density functional calculations. CrCl2 was also investigated at higher level, including coupled‐cluster and state‐average CASSCF computations. The global minima of the gas‐phase clusters consist of two‐dimensional, antiferromagnetically coupled chains of CrCl2 units forming four‐membered, doubly bridged Cr2Cl2 rings, closely resembling the solid‐state structure of α‐CrCl2. Each Cr atom in these chains has spin quantum number S=2. This suggests that the CrCl2 nucleation starts very early on the structural chain motif found in the solid. There is only a very small change in energy from the antiferromagnetically to the ferromagnetically coupled Cr atoms, which indicates little spin‐coupling between the metal centers. There is an approximately constant change in energy, about 50 kcal mol−1, with every new CrCl2 unit during cluster formation. Information about the structure of these clusters was used in the re‐analysis of high‐temperature electron‐diffraction data. The vapor at 1170 K contained about 77 % monomeric molecules, 19 % dimers, and a small amount of trimers. Monomeric CrCl2 was found to be bent with a bond angle of 149(10)°, in good agreement with our computations, which resulted in a Renner–Teller distortion of the lowest‐energy 5Πg electronic state into the bent 5B2 ground state. The vibrational spectrum of chromium dichloride is discussed and the thermodynamics of cluster formation from 1000–2000 K is examined.
Fossil Fuel Saving through a Direct Solar Energy Water Heating System
Authors: Michels Ademar , Dias Mayer Flávio , Gallon Roger , Hoffmann Ronaldo , Tiago Serafini Seimur
Published: May 2008

The global warming and energy crisis is motivating the search for sustainable power sources. The objective of this work is to analyze the economic return and quantify the reduction in the emission of pollutants, when low‐cost solar collectors are used as a partial substitute for a boiler that uses fuel oil as the energy source, in order to heat water for the swimming pools of the Physical Education Center, Federal University of Santa Maria. The collectors are made from PVC and other easily acquired materials. The estimations for energy saving are based on a collecting area of 182 m2. From knowledge of the collectors' efficiency, the mathematical demonstration shows a fuel oil saving of 13,174 kg, representing 24% of the total amount consumed per annum. The investment required for the construction and installation of the collectors is US$ 6,445 and the estimated useful live is five years. The internal rate of return is 30%. The emission of pollutants is reduced by a considerable amount of 41,213 kg CO2 equivalent/year. The use of direct sun energy as an alternative power source represents a significant economic interest as well as contributing to the mitigation of greenhouse gases.
Optimizing the Recovery of Surrogates for Bacterial Bioterrorism Agents from Ventilation Filters
Authors: Kim Seung Won , Raynor Peter C. , Kuehn Thomas H. , Goyal Sagar M. , Ramakrishnan M. A. , Anantharaman Senthilvelan , Farnsworth James E.
Published: May 2008

Heating, ventilating, and air‐conditioning (HVAC) filters have the potential to serve as long‐term integrated samplers for biological particles that may be released intentionally or unintentionally into a public building. Methods for eluting bacteria that are surrogates for potential bioterrorism agents from HVAC filters were tested for their ability to recover as high a percentage of culturable bacteria as possible. A solution of 0.02% Tween‐80 in water was an effective eluent for Bacillus globigii (BG) spores whereas phosphate‐buffered saline was the most effective eluent for vegetative bacteria. Hand shaking was a more effective agitation method for high recovery rates than vortexing or mechanical shaking. The results indicate that BG spores can be eluted successfully while maintaining essentially 100% culturability. The recovery of the vegetative bacteria Mannheimia haemolytica and Yersinia ruckeri was 80% or higher under optimal conditions. The culturability of the vegetative bacteria eluted from HVAC filters declined substantially within as little as 2 h after the bacteria were loaded onto the filter. The culturability of the BG spores eluted from filters exhibited an exponential decay subsequent to loading with a half‐life of 8–9 days.
Renal cell cancer stage migration
Authors: Kane Christopher J. , Mallin Katherine , Ritchey Jamie , Cooperberg Matthew R. , Carroll Peter R.
Published: May 2008

BACKGROUND.

Evidence exists to suggest a pattern of increasing early diagnosis of renal cell carcinoma (RCC). The aim of the study was to analyze patterns of disease presentation and outcome of RCC by AJCC stage using data from the National Cancer Data Base (NCDB) over a 12‐year period.

METHODS.

The NCDB was queried for adults diagnosed between 1993 and 2004 presenting with ICD‐O‐2 of 3 renal cell tumors arising in the kidney. Cases were classified by demographics, 2002 AJCC stage (6th edition), and histology. The Cochran‐Armitage Test for Trend was used to determine statistical significance of trends over time. Cox regression multivariate analysis was used to evaluate the impact of stage and histology on relative survival. SPSS 14.0 was used for analyses.

RESULTS.

Between 1993 and 2004 a total of 205,963 patients from the NCDB fit our case definition of RCC. Comparisons between 1993 and 2004 data show an increase in stage I disease and decrease in stage II, III, and IV disease (P≤ .001). The size of stage I tumors also decreased from a mean of 4.1 cm in 1993 to 3.6 cm in 2003. In multivariate analysis, stage, but not histology, predicted relative survival. A 3.3% increase in survival was found for patients diagnosed in 1998 compared with patients diagnosed in 1993.

CONCLUSIONS.

A greater proportion of newly diagnosed patients with RCC currently present with stage I disease compared with earlier years. Stage predicts relative survival for patients with kidney cancer. More recently diagnosed patients have improved relative survival. Cancer 2008. © 2008 American Cancer Society.
Spatial Effect of CH Dipoles on the Electron Affinity of Diamond (100)‐2×1 Adsorbed with Organic Molecules
Authors: Hoh Hui Ying , Loh Kian Ping , Sullivan Michael B. , Wu Ping
Published: May 2008

Cycloaddition of allyl organics on the dimer rows of a clean C(100)‐2×1 diamond surface can be used for the controlled functionalization of such a surface. Sticking probability measurements confirm that appreciable uptake of acetylene and butadiene occur on the clean diamond surface at room temperature. The change in electron affinity of the surface as a function of the coverage of the organic molecules is investigated with periodic DFT calculations. The presence of CH dipoles on these adsorbates modify the surface charge density and gives rise to an induced dipolar layer that modifies the electrostatic potential outside the surface. There is a significant reduction of up to 2.5 eV in electron affinity following the chemisorption of ethylene. Therefore, the adsorbed molecules play the same role as surface hydrogen in inducing the NEA condition on the clean diamond. The change in electron affinity does not scale linearly with the coverage of the organic molecules, because the spatial profile of the CH dipoles as well as the orientation of the molecules on the surface have a predominant effect on the surface charge density.
Timing error estimation for baseband multicarrier modulation
Authors: López‐Fernández Jesús , Martos‐Naya Eduardo , Díez del Río Luís , Entrambasaguas Muñoz José Tomás
Published: May 2008

In this paper, the topic of timing error estimation for baseband discrete multitone modulation is addressed in the context of high‐speed digital subscriber line applications. To the authors' best knowledge, this problem is sparsely and not in depth treated in the literature. In this study the modified Cramer–Rao lower bound is derived, two conventional estimators are considered and a new one is proposed. Behavior of these estimators is evaluated in terms of bias, variance and computational complexity in a wide variety of scenarios, concluding that the proposed estimator appears to be superior in all instances. Copyright © 2008 John Wiley & Sons, Ltd.
Production technology and characteristics of Styrian pumpkin seed oil
Authors: Fruhwirth Gilbert O. , Hermetter Albin
Published: May 2008

Cucurbita pepo subsp. pepo var. Styriaca, the so‐called Styrian oil pumpkin, is a phylogenetically young member of the Cucurbita spp. A single mutation occurred only in the 19th century and led to dark green seeds with stunted outer hulls. This mutation facilitated the production of Styrian pumpkin seed oil that became a regional specialty oil in the south‐eastern part of Europe during the last few decades. We describe in this article the production and economic value of this edible specialty oil as well as the most important parameters relevant for its quality. Furthermore, we report on its molecular composition including fatty acids, vitamins, phytosterols, minerals, polyphenols, and those compounds that are responsible for its color, taste and flavor. Finally, information is provided on potential contaminants of Styrian pumpkin seed oil as well as its putative beneficial health effects.
Self‐Assembly of Shape‐Persistent Hexagonal Macrocycles with Trimeric Bis(terpyridine)–FeII Connectivity
Authors: Li Sinan , Moorefield Charles N. , Wang Pingshan , Shreiner Carol D. , Newkome George R.
Published: May 2008

A novel family of bis(terpyridinyl) ligands was designed and constructed by facile Pd‐catalyzed coupling reactions. Subsequent terpyridine–transition‐metal complexation facilitated self‐assembly resulting in a hexagonal, trimeric series of metallomacrocycles. An enhanced solubility of a macrocycle and its bis(terpyridine) precursor possessing elongated, alkyl‐branched phenylacetylene spacers was achieved by the incorporation of dodecyloxy moieties. The characterization of the metallomacrocycles included 1H, 13C NMR, and UV spectroscopy and mass spectrometry, as well as electrochemistry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Ring Expansion of 2‐(α‐Hydroxyalkyl)azetidines: A Synthetic Route to Functionalized Pyrrolidines
Authors: Durrat François , Sanchez Monica Vargas , Couty François , Evano Gwilherm , Marrot Jérôme
Published: May 2008

A series of 2‐(α‐hydroxyalkyl)azetidines synthesized from enantiomerically pure β‐amino alcohols and presenting various patterns both on the four‐membered ring and on the adjacent hydroxy group were treated with either thionyl chloride or methanesulfonyl chloride in the presence of triethylamine. The thus‐prepared 2‐(α‐chloro‐ or α‐methanesulfonyloxyalkyl)azetidines were shown to rearrange stereospecifically into 3‐(chloro‐ or methanesulfonyloxy)pyrrolidines. When this rearrangement is conducted in the presence of an added nucleophile (NaN3, KCN, KOH, or NaOAc), the produced pyrrolidine incorporates the added nucleophile at C‐3 stereospecifically. The relative configuration of the substituents in the formed pyrrolidines is consistent with a mechanism involving the formation of an intermediate bicyclic aziridinium ion, which is opened regioselectively at the bridgehead carbon atom. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Amperometric Determination of Sugars at Activated Barrel Plating Nickel Electrodes
Authors: Sue Jun‐Wei , Hung Chi‐Jr , Chen Wei‐Chung , Zen Jyh‐Myng
Published: May 2008

We report amperometric determination of sugars by using a disposable barrel plating nickel electrode (Ni‐BPE) in this study. The activated Ni‐BPE possesses good reproducibility in flow injection analysis of sugars with a relative standard deviation of 3.16% for 10 consecutive injections of glucose. The electrocatalytic mechanism for the detection of sugars as well as the use as a detector in high‐performance liquid chromatography (HPLC) is investigated. We achieve a good separation of four sugars (glucose, fructose, sucrose, and maltose) in HPLC with favorable sensitivity at a detection potential of +0.55 V vs. Ag/AgCl. The results of wide linear calibration ranges and detection limits in the μM range meet the need of real sample analysis. This detection method is successfully used for quantitative determination of sugars in honey to identify its authentication.
Comparison of simulated wet bench fires with small‐ and intermediate‐scale fire tests
Authors: Wu Peter K. , Bill Robert G.
Published: May 2008

Fire hazard studies of clean room facilities indicated that significant losses due to fire may occur in the semiconductor industry. The present study reports the results of full‐scale wet bench fire tests conducted (1) to assess the fire hazards of existing wet bench materials not meeting the listing requirement of NFPA 318, (2) to assess the impact on wet bench fires of engineered materials with improved flammability characteristics, and (3) to compare the observed fire behavior with the results of simpler small‐ and intermediate‐scale fire tests using the same materials. The full‐scale wet bench fires were observed to be consistent in terms of chemical heat release rate, fire propagation, and smoke generation with the results of the small‐ and intermediate‐scale test results. The simpler fire tests are incorporated in FM Approvals 4910 certification for materials to be used in semiconductor fabrication facilities. The small‐scale test protocol is also standardized in NFPA 287. Copyright © 2008 John Wiley & Sons, Ltd.
Co‐occurrence of neuropsychiatric syndromes in demented and psychotic institutionalized elderly
Authors: Dechamps Arnaud , Jutand Marthe Aline , Onifade Chérifa , Richard‐Harston Sandrine , Bourdel‐Marchasson Isabelle
Published: May 2008

Objectives

To explore and determine the clinical figures of behavioral syndromes from the factor structure of the Neuropsychiatric Inventory‐Nursing Home version (NPI‐NH) in demented and psychotic patients.

Setting

Two nursing homes and two long‐term care homes.

Design

Observational, cross‐sectional.

Participants

One hundred and sixty‐three institutionalized elderly with dementia or psychosis (66.9% female), mean age 80.9 ± 9.1 years.

Measurements

The NPI‐NH includes 12 neuropsychiatric symptoms and a distress scale. The product score of frequency (F) and severity (S) ratings provides an overall score for each of the 12 items. An exploratory principal component analysis with Varimax rotation was performed on the F × S scores according to patients' diagnosis.

Results

High internal consistency of the NPI‐NH was found (α = 0.8). In demented patients a 4‐factor solution was found that explained 63.9% of the variance, with the syndromes: (a) ‘hyperactivity’; (b) ‘affective’; (c) ‘psychosis’; and (d) ‘Hallucinations’. A four‐factor solution was also found in psychotic patients, explaining 61.3% of variance, with syndromes: (a) ‘affective’; (b) ‘frontal lobe symptoms’; (c) ‘sundowning’; and (d) ‘psychomotor agitation’. A syndrome was unlikely to appear alone but was most likely to occur with other syndromes. A specific pattern of syndrome co‐occurrence were found in demented (a + b + c in 30.5% of cases) and psychotic patients (a + b + c + d in 35.2% of cases).

Conclusion

The syndrome taxonomies are consistent with the diagnostic criteria. The clinical use of syndrome co‐occurrence could help to further understand and evaluate behavioral changes in pharmacological and non‐pharmacological treatments. Copyright © 2008 John Wiley & Sons, Ltd.
Mechanical exposure and musculoskeletal disorder risk at the production system level: A framework and application
Authors: Pascual Silvia A. , Frazer Mardy B. , Wells Richard , Cole Donald
Published: May 2008

Intervention research to reduce musculoskeletal disorders (MSDs) has usually been focused at the job level. However, to intervene in and monitor change at a production system level, an approach to assess mechanical exposure and risk at this level is needed. The first purpose of this article is to present an example of production system level risk estimates. The second purpose is to compare the impact of an intervention at the job system and the production system level. One product was tracked throughout an entire production system to quantify the “product cycle” exposure and risks experienced by the low back. The intervention described decreased the predicted production system exposures and predicted risk substantially, if adopted across all departments. © 2008 Wiley Periodicals, Inc.
Quality of working life and turnover intention in information technology work
Authors: Korunka Christian , Hoonakker Peter , Carayon Pascale
Published: May 2008

High turnover has been a major issue in information technology (IT) organizations. A conceptual model to explain turnover was developed and tested in two national samples of IT and IT manufacturing work. The model postulates that quality of working life mediates the relations between job/organizational characteristics and turnover intention. The American sample consisted of 624 IT employees of five IT organizations. The Austrian sample consisted of 677 employees from an international IT production company (IT manufacturing work). A similar questionnaire was used in both studies. The model was tested with path analysis. A core model with main pathways between job demands and supervisory support to emotional exhaustion, and between emotional exhaustion and job satisfaction to turnover intention was confirmed in the national samples and in subsamples of demographics and job types. © 2008 Wiley Periodicals, Inc.
Evaluation of a digital camera image applied to PCB inspection
Authors: Jiang Bernard C. , Wang C. C. , Huang W. H.
Published: May 2008

Rapid advancement and widespread digital camera applications have made it possible to replace charge‐coupled device (CCD) cameras in automatic inspections for industrial applications. However, most digital camera applications using the automatic exposure mode may not be effective in some of the inspection environments. The reflection from a board surface in printed circuit board (PCB) inspections is one such problem area. The objective of this study is to develop a methodology to evaluate the effectiveness of using digital cameras for inspection. The indices used for evaluating digital camera image quality are the perceived image quality, the visual resolution, and the noise. An experiment was designed and conducted to determine the optimal camera parameter combination for attaining the best image quality. The desirability function was used to compare various digital camera parameter settings in considering three image quality indices for selecting the best camera‐operating conditions. Based on the developed model and the subjective image quality index, the overall image quality improved 9.4% and 13.86%, respectively. The developed methodology can be used to: (a) determine the digital camera image quality, (b) provide an improved model for determining the automatic exposure setting for digital camera designers, and (c) adjust the digital camera parameters for automatic inspection. © 2008 Wiley Periodicals, Inc.
“You will only see it, if you understand it” or occupational risk prevention from a management perspective
Authors: Swuste Paul
Published: May 2008

Evidence of a managerial influence on occupational risk prevention is largely lacking. The incidence of major accidents in high‐hazard sectors of industry does not show a downward trend. Also, the decline of fatal occupational accidents in industrialized Western countries may well be attributed to the growing employment in the relatively safe service sectors and to a phenomenon known as export of hazards. Looking more closely at accidents and disasters, we now believe they are not only caused by direct physical events, nor by human errors alone. They have their roots in organizational settings and in the sociotechnical system companies are active in. Whatever their cause, we know that (major) accidents almost always take us by surprise. Despite all our efforts and systems, we seem unable to foresee or predict these events. It seems our management systems are looking at the wrong items. Critics from small‐ and medium‐sized enterprises also point in that direction; management systems are too bureaucratic and lack a focus on hazard and risk identification. Apparently, we fail to incorporate the main ingredients of accident causation in our management systems. This article will discuss current models and presentations. In reference to the title of this article, the possibility to integrate these presentations into management systems will be discussed. This article is based on the presentation given at the 4th International Conference on Occupational Risk Prevention, Sevilla, Spain, May 10–12, 2006. © 2008 Wiley Periodicals, Inc.
Human factors and usability in service quality measurement
Authors: Strawderman Lesley , Koubek Rick
Published: May 2008

The purpose of this study was to develop a modified measurement instrument for service quality that includes human factor considerations. Tangibles, reliability, responsiveness, assurance, and empathy were dimensions commonly used to measure service quality through a survey instrument termed SERVQUAL. A sixth dimension, usability, was added in a modified survey instrument termed SERVUSE. To examine the predictive power of both instruments, 200 patients at an on‐campus health clinic were surveyed. The survey measured subject expectations and perceptions regarding the service system. Gap scores were calculated as the difference between these two measures. Positive gap scores reflected the exceeding of customer expectations. Negative gap scores reflected a failure to meet these expectations. The three response variables were perceived quality, satisfaction, and behavioral intention. Usability was found to be a significant predictor of all response variables. It also adds significant predictive value to the regression models when measuring behavioral intention. © 2008 Wiley Periodicals, Inc.