bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychological empowerment, job insecurity and employee engagement
Authors: Stander Marius W. , Rothmann Sebastiaan
Published: May 2010

Orientation: The psychological empowerment of employees might affect their engagement. However, psychological empowerment and employee engagement might also be influenced by job insecurity.Research purposes: The objective of this study was to examine the relationship between psychological empowerment, job insecurity and employee engagement.Motivation for the study: Employee engagement results in positive individual and organisational outcomes and research information about the antecedents will provide valuable information for the purposes of diagnosis and intervention.Research design, approach and method: A correlational design was used. Survey design was conducted among 442 employees in a government and a manufacturing organisation. The measuring instruments included the Psychological Empowerment Questionnaire, the Job Insecurity Inventory, and the Utrecht Work Engagement Scale.Main findings: Statistically significant relationships were found between psychological empowerment, job insecurity and employee engagement. A multivariate analysis of variance showed that affective job insecurity had a main effect on three dimensions of psychological empowerment (viz. competence, meaning and impact) and on employee engagement. Affective job insecurity moderated the effect of psychological empowerment on employee engagement.Practical implications: The implication of the results is that interventions that focus on the psychological empowerment of employees (viz. meaningfulness, competence, self-determination and impact) will contribute to the engagement (vigour, dedication and absorption) of employees. If job insecurity is high, it is crucial to attend to the psychological empowerment of employees.Contribution: This study contributes to knowledge about the conditions that precede employee engagement, and shows that the dimensions of psychological empowerment (namely experienced meaningfulness, competence, impact and self-determination) play an important role in this regard.
Seasonal and interannual change in a Chesapeake Bay eelgrass community: Insights into biotic and abiotic control of community structure
Authors: Douglass James G. , Douglass James G. , France Kristin E. , France Kristin E. , Richardson J. Paul , Duffy J. Emmett
Published: May 2010

We characterized the seasonal and interannual variation in macrophytes, epiphytes, invertebrate herbivores, small demersal predators, and physicochemical characteristics of an eelgrass (Zostera marina) bed in Chesapeake Bay, Virginia, over 10 yr, to explore the relative importance of abiotic and biotic forcing on community composition and abundance. Our hypotheses were (1) physicochemical drivers affect community structure directly, (2) bottom‐up trophic control is evidenced by positive covariance among trophic levels, (3) top‐down control generates inverse patterns of abundance at adjacent trophic levels, and (4) species diversity among herbivores contributes to temporal stability. Composition and abundance of eelgrass‐associated species varied strongly among seasons and years. Much of this variation correlated with temperature and salinity anomalies, and multivariate analysis grouped communities roughly by season, supporting our first hypothesis. Severe seagrass loss during the hot summer of 2005 shifted the community toward a novel composition, but community structure rebounded within a year. Evidence for trophic control was mixed: selected taxa showed patterns consistent with top‐down or bottom‐up control, but these patterns generally disappeared at the level of whole years and entire trophic levels. Our ability to detect trophic effects may have been limited, however, by consumer movement or changing behavioral responses to resource availability and predation. There was also little evidence that diversity stabilized total herbivore abundance. Although consumer effects on lower levels were inconsistent, the strong physicochemical forcing of community structure supports suggestions that eelgrass communities are highly vulnerable to natural and anthropogenic changes in climate and hydrography.
Dimethyl sulfoniopropionate and dimethyl sulfide production in response to photoinhibition in Emiliania huxleyi
Authors: Archer Stephen D. , Ragni Maria , Webster Richard , Airs Ruth L. , Geider Richard J.
Published: May 2010

The response in intracellular dimethyl sulfoniopropionate (DMSP) and dissolved DMSP and dimethyl sulfide (DMS) concentrations when Emiliania huxleyi was exposed to acute (1‐h) increases in photon flux densities of photosynthetically active radiation (PAR) and ultraviolet (UV) radiation was examined in cells acclimated to low light (LL, 30 µmol photons m−2 s−1) and high light (HL, 300 vmol photons m−2 s−1). LL‐acclimated cells displayed greater photoinhibition, assessed as a decrease in maximum photochemical efficiency (Fv : Fm). Photoinhibition was increased by exposure to UV wavelengths. LL‐acclimated cells also exhibited more light dissipation through the xanthophyll cycle, evident as changes in de‐epoxidation state. Greater photoinhibition in LL‐acclimated cells corresponded with increased accumulation of DMSP of 21% ± 4% relative to initial concentrations, contrasting with a slight decrease of 5% ± 6% in HL‐acclimated cells. Exposure to UV appeared to decrease the rates of intracellular accumulation of DMSP. Conversely, PAR + UV exposure stimulated the net production of dissolved DMSP and DMS in both HL‐acclimated and LL‐acclimated cultures, compared with high PAR alone. The results indicate a direct link between acute photo‐oxidative stress and DMSP synthesis by E. huxleyi. The physiological basis for increased release of DMSP and DMS from cells due to high PAR + UV exposure is unclear. However, the timescales of changes in intracellular DMSP, dissolved DMSP, and DMS are consistent with variations in light intensity experienced by phytoplankton in a turbulent mixed layer and are similar to rates of change in photosynthetic parameters associated with photoacclimation.
Investigation of VLF and HF waves showing seismo-ionospheric anomalies induced by the 29 September 2009 Samoa earthquake (Mw=8.1)
Authors: Akhoondzadeh M. , Parrot M. , Saradjian M. R.
Published: May 2010

Abstract. In Samoa Islands, a powerful earthquake took place at 17:48:10.99 UTC (06:48:10.99 LT) on 29 September 2009 with a magnitude Mw=8.1. Using ICE (Instrument Champ Electrique) and IMSC (Instrument Magnetic Search Coil) experiments onboard the DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite we have surveyed possible variations in electromagnetic signals transmitted by the ground-based VLF transmitter NPM in Hawaii and in HF plasma waves close to the Samoa earthquake during the seismic activity. The indices Dst and Kp were used to distinguish pre-earthquake anomalies from the other anomalies related to the geomagnetic activities. In a previous study we have shown that anomalies in IAP (plasma analyzer) and ISL (Langmuir probe) experiments onboard the DEMETER and also TEC (Total Electron Content) data appear 1 to 5 days before the Samoa earthquake. In this paper we show that the anomalies in the VLF transmitter signal and in the HF range appear with the same time scale. The lack of significant geomagnetic activities indicates that these anomalous behaviors could be regarded as seismo-ionospheric precursors. It is also shown that comparative analysis is more effective in seismo-ionospheric studies.
Screening of the Interactions Between Mg‐PSZ and TRIP‐Steel and Its Alloys During Sintering
Authors: Weigelt Christian , Giersberg Sarah , Wenzel Claudia , Aneziris Christos G.
Published: May 2010

Ceramic–steel compound materials are used in a wide range of applications up to date. Major advantages are the mechanical properties due to the combination of brittle ceramic with tough steel. This study deals with effects of the sintering process on austenitic TRIP‐steel/Mg‐PSZ composite materials for mechanical load applications. Both, the FeCrNisteel and partially stabilized zirconia offer their special mechanical behavior only in a metastable state. The ability of phase transformation depends mainly on the chemical composition. Mutual interactions of the alloying metals (Cr, Ni, Mn, and Fe) and the ceramic stabilizer (MgO) during sintering may prevent the martensitic phase transformation. This may cause disadvantageous mechanical behavior on mechanical load in use.
Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials
Authors: Zhao Yonghao , Zhu Yuntian , Lavernia Enrique J.
Published: May 2010

The low ductility that is consistently associated with bulk nanostructured (NS) materials has been identified as perhaps the single most critical issue that must be resolved before this novel class of materials can be used in a wide variety of applications. Not surprisingly, a number of published studies, published mostly after 2000, identify the issue of low ductility and describe strategies to improve ductility. Details of these strategies were discussed in review papers published by Koch and Ma in 2005 and 2006, respectively.15,16 In view of continued efforts and recent results, in this paper we describe progress in attempting to address the low ductility of NS materials, after 2006. We first analyze the fundamental reasons for the observed low ductility of bulk NS materials, and summarize early (prior to 2006) attempts to enhance the ductility of bulk NS materials, which often sacrificed the strength. Then, we review recent progress in developing strategies for improving the tensile ductility of bulk NS materials, which involve mainly microstructure modifications, after 2006. Different from early efforts, these new strategies strive to increase the tensile ductility while increasing/maintaining the strength simultaneously. In addition, the influence of tensile testing conditions, including temperature, strain rate, tensile specimen size and geometry, and strain measurement methods, on tensile ductility of NS materials will also be reviewed. Finally, we identify several issues that will require further, in depth analysis in the future.
Fractal Approach to Hierarchically Evolved Laser Processed CaP Coatings
Authors: Kurella Anil Kumar , Dahotre Narendra
Published: May 2010

This paper discusses a fractal approach to understand nature inspired laser surface engineered coatings. Via a laser surface engineering process a multi‐scale CaTiO3 coating was synthesized on Ti alloy surface. At faster laser processing speeds star like CaTiO3 features evolved inside rings rich in calcium phosphate and TiO2. The porosity developed through the distribution of these particles results in a multi‐scale distribution. Fractal analysis revealed that such laser processed surfaces had consistent fractal dimension over multiple length scales. This multi‐scale and multi‐phase surface microstructure contributed to enhanced biomimetic precipitation.
Phase Transformations During High‐Pressure Torsion of Pure Zr and of a Zr‐2.5%Nb Alloy
Authors: Zhilyaev Alexander P. , Sharafutdinov Alfred V. , Pérez‐Prado M. Teresa
Published: May 2010

Zirconium at normal conditions (room temperature and atmospheric pressure) has an HCP structure with lattice parameters a = 3.2313 Å and c = 5.1477 Å (α‐phase). During loading under hydrostatic conditions in diamond anvil cells, a transition from the α ‐phase to an ω‐phase occurs at a pressure between 2 and 6 GPa and from ω to β (bcc) at 30 GPa. It has been recently reported that the α to ω + β transformation might be induced by HPT processing. The resulting microstructures are stable at room temperature and atmospheric pressure. This paper explores the influence of previous processing steps and of composition in the feasibility of the HPT induced α to α + β transformation. It will be shown that neither previous quenching nor high temperature HPT processing prevents the transformation from occurring during subsequent room temperature HPT. The addition of elements such as Nb also seems to favor the transformation. Understanding well the potential of HPT to stabilize high‐pressure phases at normal conditions might be critical, as it will open a whole new range of applications for already existing materials.
Biphasic Resorbable Calcium Phosphate Ceramic for Bone Implants and Local Alendronate Delivery
Authors: Banerjee Shashwat S. , Bandyopadhyay Amit , Bose Susmita
Published: May 2010

A novel biphasic calcium phosphate ceramic composed of tricalcium phosphate (TCP) and calcium pyrophosphate (CP) is synthesized in order to tailor the biodegradation behavior of the ceramic. The results show that biphasic TCP/CP ceramic has a strength of 62.2 ± 2.1 MPa, which is superior to single‐phase TCP and CP ceramics, which show strengths of 44.3 ± 3.0 and 53.0 ± 4.8 MPa, respectively. In addition, biphasic TCP/CP ceramic displays a controlled strength degradation from 62.2 ± 2.1 to 40.5 ± 1.0 MPa in stimulated body fluid over a period of 28 d. An in vitro cell materials interaction study using human fetal osteoblast cells indicates that TCP/CP ceramic is cytocompatible. TCP/CP ceramic also show a good loading capacity for alendronate. Adsorption of alendronate (AD) on the TCP/CP surface is found to proceed via ligand exchange mechanism and the in vitro release profile of AD from TCP/CP surface is characterized by an initial fast release followed by a slow and sustained release. Strong electrostatic interactions between AD groups and surface Ca2+ ions enable the slow and sustained release of AD. These results demonstrate that the newly developed biphasic ceramic, with its controlled strength degradation and drug release, shows promise for use in orthopedic and tissue engineering applications.
Nanoscale Grain Refinement and H‐Sorption Properties of MgH2 Processed by High‐Pressure Torsion and Other Mechanical Routes
Authors: Leiva Daniel Rodrigo , Jorge Alberto Moreira , Ishikawa Tomaz Toshimi , Huot Jacques , Fruchart Daniel , Miraglia Salvatore , Kiminami Claudio Shyinti , Botta Walter Jose
Published: May 2010

MgH2 is a promising material for solid‐state hydrogen storage due to its high gravimetric and volumetric storage capacity and its relatively low cost. Severe plastic deformation (SPD) processing techniques are being explored as an alternative to high‐energy ball‐milling (HEBM) in order to obtain more air resistant materials and reduce processing times. In this work, Mg, MgH2, and MgH2–Fe mixtures were severely mechanically processed by different techniques such as high‐pressure torsion (HPT), extensive cold forging, and cold rolling. A very significant grain refinement was achieved when using MgH2 instead of Mg as raw material. The mean crystallite sizes observed ranged from 10 to 30 nm, depending on the processing conditions. Enhanced H‐sorption properties were observed for the MgH2‐based nanocomposites processed by HPT when compared with MgH2 mixtures. Additionally, cold forging and cold rolling also proved effective in nanostructuring MgH2. These results suggest a high potential for innovative application with the use of low cost mechanical processing routes to produce Mg‐based nanomaterials with attractive hydrogen storage properties.
Global Techniques for Characterizing Phase Transformations – A Tutorial Review
Authors: Perez Michel , Lame Olivier , Deschamps Alexis
Published: May 2010

To characterize phase transformations, it is necessary to get both local and global information. No experimental technique alone is capable of providing these two types of information. Local techniques are very useful to get information on morphology and chemistry but fail to deal with global information like phase fraction and size distribution since the analyzed volume is very limited. This is why, it is important to use, in parallel, global experimental techniques, that investigate the response of the whole sample to a stimulus (electrical, thermal, mechanical…). The aim of this paper is not to give an exhaustive list of all global experimental techniques, but to focus on a few examples of recent studies dealing with the characterization of phase transformations, namely (i) the measurement of the solubility limit of copper in iron, (ii) the tempering of martensite, (iii) the control of the crystallinity degree of a ultra high molecular weight polyethylene and (iii) a precipitation sequence in aluminum alloys. Along these examples, it will be emphasized that any global technique requires a calibration stage and some modeling to connect the measured signal with the investigated information.
Temperature‐Dependent Solid‐State Reactions With and Without Kirkendall Effect in Al2O3/ZnO, Fe2O3/ZnO, and CoXOY/ZnO Oxide Thin Film Systems
Authors: Zolotaryov Andriy , Goetze Silvana , Zierold Robert , Novikov Dmitri , Birajdar Balaji , Hesse Dietrich , Nielsch Kornelius
Published: May 2010

Temperature‐dependent solid‐state reactions and the occurrence of the Kirkendall effect are studied in thin film oxide systems applying optical reflection microscopy, X‐ray reflectivity, (scanning) transmission electron microscopy, grazing‐incidence X‐ray diffraction measurements, and SQUID magnetometry. The efficiency of the simultaneous application of different analytical methods for the precise selection and investigation of the most interesting samples is demonstrated first on the example of the Al2O3/ZnO system, for which the spinel formation after a solid‐state reaction and the formation of Kirkendall voids were already reported. The demonstrated methodology is then applied to study Fe2O3/ZnO and CoXOY/ZnO film pairs. The investigations clearly demonstrate the temperature‐driven formation of a ferromagnetic spinel by a solid state reaction involving the Kirkendall effect in the Fe2O3/ZnO system, already after an annealing at 600 °C for 1 h. We also report on the solid state reaction in the CoXOY/ZnO system after annealing at 700 °C for 1 h, however without the Kirkendall effect and without any evidence of ferromagnetism of the final state.
Use of Nanoparticles to Study and Manipulate Plant cells
Authors: Eggenberger Kai , Frey Nicole , Zienicke Benjamin , Siebenbrock Jan , Schunck Tobias , Fischer Reinhard , Bräse Stefan , Birtalan Esther , Nann Thomas , Nick Peter
Published: May 2010

Fluorescence microscopy has developed into a key technology of the postgenomic era in biology, because it combines structural information with molecular specificity. However, the resolution of this approach is limited by bleaching and optical cross‐reference of the fluorescent labels. Fluorescent semiconductor quantum dots (QDs) provide excellent bleaching stability and tunable emission spectra, and therefore would be an excellent alternative to overcome these limitations. However, to apply them to cell biology, three challenges have to be met: bioconjugation to molecular probes that confer the specificity of the label, passage through the external barriers of the cell, and suppression of toxic side effects of the nanoparticles. In plant cells that are ensheathed by a cellulosic cell wall, these challenges are especially prominent. Moreover, plants are located at the start of the food chain and thus of high relevance for the ecotoxicological assessment of nanomaterials. We have therefore explored the application of nanoparticles to plant cell biology. We have first evaluated different strategies to visualize microtubules by QDs in vitro and in cellula. By using silica‐coated QDs coupled to anti‐tubulin antibodies we were able to image microtubules in tobacco BY‐2 cells by direct immunofluorescence making use of the superior bleaching stability of the nanoparticle label. To adapt this tool for in vivo imaging, we have successfully employed Trojan Peptoids as vehicles into living tobacco cells. We want to extend this strategy not only to use functionalized nanoparticles for life‐cell imaging, but also to adapt them as tool to manipulate intracellular architecture.
Surface Structures and Osteoblast Activity on Biomedical Polytetrafluoroethylene Treated by Long‐Pulse, High‐Frequency Oxygen Plasma Immersion Ion Implantation
Authors: Tong Liping , Kwok Dixon T. K. , Wang Huaiyu , Wu Lijun , Chu Paul K.
Published: May 2010

Polytetrafluoroethylene (PTFE) is a biologically safe polymer used widely in clinical medicine including oral and orthopedic surgery. However, the high bio‐inertness of PTFE has hampered wider applications in the biomedical fields. In this work, we extend the treatment time in long‐pulse, high‐frequency oxygen plasma immersion ion implantation of PTFE and a more superhydrophobic surface with a water contact angle of 160° is created. X‐ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) reveal that the optimized long‐pulse, high‐frequency oxygen plasma immersion ion implantation process induces a rougher surface and to a lesser extent alters the surface oxygen concentration on the PTFE. Our data, especially long‐term contact angles, suggest that the superhydrophobility stems from surface roughness alteration. Furthermore, the activity of MC3T3‐E1 osteoblasts cultured on the treated surfaces is promoted in terms of quantities and morphology.
Degradation Mechanisms in Small‐Molecule and Polymer Organic Light‐Emitting Diodes
Authors: So Franky , Kondakov Denis
Published: May 2010

Degradation in organic light‐emitting diodes (OLEDs) is a complex problem. Depending upon the materials and the device architectures used, the degradation mechanism can be very different. In this Progress Report, using examples in both small molecule and polymer OLEDs, the different degradation mechanisms in two types of devices are examined. Some of the extrinsic and intrinsic degradation mechanisms in OLEDs are reviewed, and recent work on degradation studies of both small‐molecule and polymer OLEDs is presented. For small‐molecule OLEDs, the operational degradation of exemplary fluorescent devices is dominated by chemical transformations in the vicinity of the recombination zone. The accumulation of degradation products results in coupled phenomena of luminance‐efficiency loss and operating‐voltage rise. For polymer OLEDs, it is shown how the charge‐transport and injection properties affect the device lifetime. Further, it is shown how the charge balance is controlled by interlayers at the anode contact, and their effects on the device lifetime are discussed.
Fluorous Surface‐Active Distannoxane Catalysts
Authors: Orita Akihiro , Tanabe Shoko , Ono Tatsuhiko , Otera Junzo
Published: May 2010

Fluorous distannoxanes (XRf2SnOSnRf2X)2⋅n H2O (Rf=C6F13C2H4) (1: X=C8F17SO3, n=10; 4: X=Cl, n=0) (1) catalyze the Mukaiyama aldol reaction and the allylation of aldehydes with tetraallyltin at room temperature in fluorous/organic biphasic solvent systems, in which the reactions proceed more rapidly than in a single organic or fluorous solvent. Due to the unique surface activity of 1, the catalyst, organic substrate(s), and reagent(s) are distributed in both organic and fluorous phases to facilitate smooth reactions. Upon dilution with toluene after the reaction, the catalyst concentrates to the fluorous phase, while the organic substances migrate to the organic phase to effect facile catalyst recovery and recycling. By virtue of such a unique solvophilicity, a new version of fluorous biphase technology has been developed.
Visceral fat is associated with lower brain volume in healthy middle‐aged adults
Authors: Debette Stéphanie , Beiser Alexa , Hoffmann Udo , DeCarli Charles , O'Donnell Christopher J. , Massaro Joseph M. , Au Rhoda , Himali Jayandra J. , Wolf Philip A. , Fox Caroline S. , Seshadri Sudha
Published: May 2010

Objective

Midlife obesity has been associated with an increased risk of dementia. The underlying mechanisms are poorly understood. Our aim was to examine the cross‐sectional association of body mass index (BMI), waist circumference (WC), waist‐to‐hip ratio (WHR), and computed tomography (CT)‐based measurements of subcutaneous (SAT) and visceral (VAT) adipose tissue with various magnetic resonance imaging (MRI) markers of brain aging in middle‐aged community adults.

Methods

Participants from the Framingham Offspring cohort were eligible if in addition to having measurements of BMI, WC, WHR, SAT, and VAT, they had undergone a volumetric brain MRI scan with measurements of total brain volume (TCBV), temporal horn volume (THV), white matter hyperintensity volume (WMHV), and MRI‐defined brain infarcts (BI). All analyses were adjusted for age, sex, and time interval between abdominal CT and brain MRI.

Results

In a sample of 733 community participants (mean age, 60 years; 53% women), we observed an inverse association of BMI (estimate by standard deviation unit ± standard error = −0.27 ± 0.12; p = 0.02), WC (−0.30 ± 0.12; p = 0.01), WHR (−0.37 ± 0.12; p = 0.02), SAT (−0.23 ± 0.11; p = 0.04), and VAT (−0.36 ± 0.12; p = 0.002) with TCBV, independent of vascular risk factors. The association between VAT and TCBV was the strongest and most robust, and was also independent of BMI (−0.35 ± 0.15; p = 0.02) and insulin resistance (−0.32 ± 0.13; p = 0.01). When adjusting for C‐reactive protein levels, the associations were attenuated (−0.17 ± 0.13; p = 0.17 for VAT). No consistently significant association was observed between the anthropometric or CT‐based abdominal fat measurements and THV, WMHV, or BI.

Interpretation

In middle‐aged community participants, we observed a significant inverse association of anthropometric and CT‐based measurements of abdominal, especially visceral, fat with total brain volume. ANN NEUROL 2010
Optimization of electrospinning an SU‐8 negative photoresist to create patterned carbon nanofibers and nanobeads
Authors: Steach Jeremy K. , Clark Jonathan E. , Olesik Susan V.
Published: May 2010

The optimization of electrospinning SU‐8 2100 negative photoresist was performed to create carbon micro/nanofibers and beads that can be patterned after electrospinning by using UV radiation. The fiber diameters had a range of 300 nm to 1 μm, based upon the selected electrospinning parameters. Low concentrations of the SU‐8 2100 resulted in beads while specific higher concentrations produced well‐defined fibers. Fibers and beads were converted to carbon through pyrolysis and retained their three dimensional structure. By utilizing the photosensitive properties of the SU‐8 negative photoresist, the electrospun fibers were patterned by UV photolithography. The fibers and beads were characterized by SEM and Raman microscopy, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Possible use of ultra‐fine acrylonitrile butadiene rubber powder as filler in natural rubber vulcanizates
Authors: Sae‐Oui Pongdhorn , Sirisinha Chakrit , Thaptong Puchong , Intiya Weenusarin
Published: May 2010

Possible use of ultra‐fine acrylonitrile butadiene rubber powder (UFNBRP) as a filler for natural rubber (NR) was investigated. The UFNBRP was added into NR at various concentrations, and the compound properties were determined. It is found that, with increasing UFNBRP loading, the compound viscosity is increased, whereas both scorch time and optimum curing time are significantly reduced. The results also reveal that UFNBRP has negative effect not only on crosslink density but also on most mechanical properties of the vulcanizate, such as tensile strength, tear strength, compression set, and abrasion resistance. The deterioration of these mechanical properties is thought to arise mainly from the combined effect of large phase size of the dispersed UFNBRP and low interfacial adhesion taking place from the polarity difference between UFNBRP and NR. Interestingly, it is found that, after aging, UFNBRP could promote postcuring phenomenon leading to increases of both relative 100% modulus and relative tensile strength. Oil resistance is also found to improve considerably with increasing UFNBRP loading. This improvement is mainly attributed to the dilution effect, i.e., the higher the UFNBRP loading, the lower the NR portion and, thus, the greater the oil resistance of the vulcanizate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Dissecting galaxies with quantitative spectroscopy of the brightest stars in the Universe
Authors: Kudritzki R.‐P.
Published: May 2010

Measuring distances to galaxies, determining their chemical composition, investigating the nature of their stellar populations and the absorbing properties of their interstellar medium are fundamental activities in modern extragalactic astronomy helping to understand the evolution of galaxies and the expanding universe. The optically brightest stars in the universe, blue supergiants of spectral A and B, are unique tools for these purposes. With absolute visual magnitudes up to MV ≃ ‐9.5 they are ideal to obtain accurate quantitative information about galaxies through the powerful modern methods of quantitative stellar spectroscopy. The spectral analysis of individual blue supergiant targets provides invaluable information about chemical abundances and abundance gradients, which is more comprehensive than the one obtained from HII regions, as it includes additional atomic species, and which is also more accurate, since it avoids the systematic uncertainties inherent in the strong line studies usually applied to the HII regions of spiral galaxies beyond the Local Group. Simultaneously, the spectral analysis yields stellar parameters and interstellar extinction for each individual supergiant target, which provides an alternative very accurate way to determine extragalactic distances through a newly developed method, called the Flux‐weighted Gravity–Luminosity Relationship (FGLR). With the present generation of 10 m‐class telescopes these spectroscopic studies can reach out to distances of 10 Mpc. The new generation of 30 m‐class telescopes will allow to extend this work out to 30 Mpc, a substantial volume of the local universe (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative solar spectroscopy
Authors: Wilhelm K.
Published: May 2010

Quantitative solar spectroscopy must be based on calibrated instrumentation. The basic requirement of a calibration, i.e., a comparison between the instrument under test and a primary laboratory standard through appropriate procedures, will be briefly reviewed, and the application to modern space instruments will be illustrated. Quantitative measurements of spectral radiances with high spectral and spatial resolutions as well as spectral irradiances yield detailed information on temperatures, electron densities, bulk and turbulent motions, element abundances of plasma structures in various regions of the solar atmosphere – from the photosphere to the outer corona and the solar wind. The particular requirements for helioseismology and magnetic‐field observations will not be covered in any depth in this review. Calibration by a laboratory standard is necessary, but not sufficient, because an adequate radiometric stability can only be achieved together with a stringent cleanliness concept that rules out a contamination of the optical system and the detectors as much as possible. In addition, there is a need for calibration monitoring through inter‐calibration and other means (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopy of solar neutrinos
Authors: Wurm M. , von Feilitzsch F. , Göger‐Neff M. , Lachenmaier T. , Lewke T. , Meindl Q. , Möllenberg R. , Oberauer L. , Potzel W. , Tippmann M. , Traunsteiner C. , Winter J.
Published: May 2010

In the last years, liquid‐scintillator detectors have opened a new window for the observation of low‐energetic astrophysical neutrino sources. In 2007, the solar neutrino experiment Borexino began its data‐taking in the Gran Sasso underground laboratory. High energy resolution and excellent radioactive background conditions in the detector allow the first‐time spectroscopic measurement of solar neutrinos in the sub‐MeV energy regime. The experimental results of the Beryllium 7 neutrino flux measurements (Arpesella et al. 2008b) as well as the prospects for the detection of solar Boron 8, pep and CNO neutrinos are presented in the context of the currently discussed ambiguities in solar metallicity. In addition, the potential of the future SNO+ and LENA experiments for high‐precision solar neutrino spectroscopy will be outlined (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stellar archaeology: Exploring the Universe with metal‐poor stars
Authors: Frebel A.
Published: May 2010

The abundance patterns of the most metal‐poor stars in the Galactic halo and small dwarf galaxies provide us with a wealth of information about the early Universe. In particular, these old survivors allow us to study the nature of the first stars and supernovae, the relevant nucleosynthesis processes responsible for the formation and evolution of the elements, early star‐ and galaxy formation processes, as well as the assembly process of the stellar halo from dwarf galaxies a long time ago. This review presents the current state of the field of “stellar archaeology” – the diverse use of metal‐poor stars to explore the high‐redshift Universe and its constituents. In particular, the conditions for early star formation are discussed, how these ultimately led to a chemical evolution, and what the role of the most iron‐poor stars is for learning about Population III supernovae yields. Rapid neutron‐capture signatures found in metal‐poor stars can be used to obtain stellar ages, but also to constrain this complex nucleosynthesis process with observational measurements. Moreover, chemical abundances of extremely metal‐poor stars in different types of dwarf galaxies can be used to infer details on the formation scenario of the halo and the role of dwarf galaxies as Galactic building blocks. I conclude with an outlook as to where this field may be heading within the next decade. A table of ~ 1000 metal‐poor stars and their abundances as collected from the literature is provided in electronic format (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐fidelity spectroscopy at the highest resolutions
Authors: Dravins D.
Published: May 2010

High‐fidelity spectroscopy presents challenges for both observations and in designing instruments. High‐resolution and high‐accuracy spectra are required for verifying hydrodynamic stellar atmospheres and for resolving intergalactic absorption‐line structures in quasars. Even with great photon fluxes from large telescopes with matching spectrometers, precise measurements of line profiles and wavelength positions encounter various physical, observational, and instrumental limits. The analysis may be limited by astrophysical and telluric blends, lack of suitable lines, imprecise laboratory wavelengths, or instrumental imperfections. To some extent, such limits can be pushed by forming averages over many similar spectral lines, thus averaging away small random blends and wavelength errors. In situations where theoretical predictions of lineshapes and shifts can be accurately made (e.g., hydrodynamic models of solar‐type stars), the consistency between noisy observations and theoretical predictions may be verified; however this is not feasible for, e.g., the complex of intergalactic metal lines in spectra of distant quasars, where the primary data must come from observations. To more fully resolve lineshapes and interpret wavelength shifts in stars and quasars alike, spectral resolutions on orderR= 300 000 or more are required; a level that is becoming (but is not yet) available. A grand challenge remains to design efficient spectrometers with resolutions approachingR= 1 000 000 for the forthcoming generation of extremely large telescopes (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probing dark matter, galaxies and the expansion history of the Universe with Lyα in absorption and emission
Authors: Haehnelt M.G.
Published: May 2010

Lyα radiation is an important diagnostic tool in a wide range of astrophysical environments. I will first describe here how measurements of the matter power spectrum on small scales from Lyα forest data constrain the mass of dark matter particles. I then will report on an ambitious program of searching for very faint spatially extended Lyα emission at z ∼ 3 which has led to the discovery of a new population of faint Lyα emitters which I will argue should be identified with the long searched for host galaxies of damped Lyα absorbers. Finally, I will discuss the possibility of measuring the redshift drift of Lyα absorption features and therefore the change of the expansion rate of the Universe in real time with the ultra‐stable high‐resolution spectrograph CODEX proposed for the E‐ELT (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Metallicity and kinematical clues to the formation of the Local Group
Authors: Wyse R.F.G.
Published: May 2010

The kinematics and elemental abundances of resolved stars in the nearby Universe can be used to infer conditions at high redshift, trace how galaxies evolve and constrain the nature of dark matter. This approach is complementary to direct study of systems at high redshift, but I will show that analysis of individual stars allows one to break degeneracies, such as between star formation rate and stellar Initial Mass Function, that complicate the analysis of unresolved, distant galaxies (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pulsations and planets: The asteroseismology‐extrasolar‐planet connection
Authors: Schuh S.
Published: May 2010

The disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high‐precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow‐up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space‐ or ground‐based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond‐mainstream area are presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Open clusters and the galactic disk
Authors: Röser S. , Kharchenko N.V. , Piskunov A.E. , Schilbach E. , Scholz R.‐D. , Zinnecker H.
Published: May 2010

It is textbook knowledge that open clusters are conspicuous members of the thin disk of our Galaxy, but their role as contributors to the stellar population of the disk was regarded as minor. Starting from a homogenous stellar sky survey, the ASCC‐2.5, we revisited the population of open clusters in the solar neighbourhood from scratch. In the course of this enterprise we detected 130 formerly unknown open clusters, constructed volume‐ and magnitude‐limited samples of clusters, re‐determined distances, motions, sizes, ages, luminosities and masses of 650 open clusters. We derived the present‐day luminosity and mass functions of open clusters (not the stellar mass function in open clusters), the cluster initial mass function CIMF and the formation rate of open clusters. We find that open clusters contributed around 40 percent to the stellar content of the disk during the history of our Galaxy. Hence, open clusters are important building blocks of the Galactic disk (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
VLT‐CRIRES: “Good Vibrations” Rotational‐vibrational molecular spectroscopy in astronomy
Authors: Käufl H.U.
Published: May 2010

Near‐Infrared high spectral and spatial resolution spectroscopy offers new and innovative observing opportunities for astronomy. The “traditional” benefits of IR‐astronomy – strongly reduced extinction and availability of adaptive optics – more than offset for many applications the compared to CCD‐based astronomy strongly reduced sensitivity. Especially in high resolution spectroscopy interferences by telluric lines can be minimized. Moreover for abundance studies many important atomic lines can be accessed in the NIR. A novel spectral feature available for quantitative spectroscopy are the molecular rotational‐vibrational transitions which allow for fundamentally new studies of condensed objects and atmospheres. This is also an important complement to radio‐astronomy, especially with ALMA, where molecules are generally only observed in the vibrational ground state. Rot‐vib transitions also allow high precision abundance measurements – including isotopic ratios – fundamental to understand the thermo‐nuclear processes in stars beyond the main sequence. Quantitative modeling of atmospheres has progressed such that the unambiguous interpretation of IR‐spectra is now well established. In combination with adaptive optics spectro‐astrometry is even more powerful and with VLT‐CRIRES a spatial resolution of better than one milli‐arcsecond has been demonstrated. Some highlights and recent results will be presented: our solar system, extrasolar planets, star‐ and planet formation, stellar evolution and the formation of galactic bulges (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conformations of Betanova in aqueous trifluoroethanol
Authors: Chagolla Danny P. , Gerig John T.
Published: May 2010

Conformations of the designed peptide Betanova in 42% trifluoroethanol/water (v/v) were explored. Circular dichroism (CD) observations provided no evidence for the presence of significant amounts of β‐structures in water, in TFE/water, or in ethanol/water. Nuclear magnetic resonance (NMR) diffusion experiments showed no significant difference in the hydrodynamic radius of the peptide in water and in 42% TFE/water. However, calculations indicated that the hydrodynamic radii of the triple‐stranded β‐sheet, originally proposed for Betanova by Kortemme et al. (Science 1998, 281, 253‐256), and a variety of partially folded forms of Betanova would be similar and likely could not be convincingly distinguished by diffusion experiments. Temperature coefficients (Δδ/ΔT) of the peptide NH chemical shifts are similar in water and 42% TFE/water, implying that most of these protons are highly solvent exposed in both solvents and likely do not participate in intramolecular hydrogen bonding interactions. Possible exceptions to this conclusion are the Lys9 and Lys15 residues, where a more positive coefficient may indicate that these residues are involved to some extent in local turn structures. Peptide proton–solvent fluorine intermolecular nuclear Overhauser effect (NOE)s at 25°C were consistent with the presence of a mixture of conformations, which could include the triple‐stranded β‐sheet structure as a minor component. At 0°C, peptide‐TFE NOEs indicated that TFE interacts strongly enough with many protons of Betanova that alcohol‐peptide interactions persist for times of the order of nanoseconds, appreciably longer than the encounter time characteristic of mutual diffusion of TFE and the solute. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 893–903, 2010.
The role of disulfide bonds and N‐terminus in the structural properties of hepcidins: Insights from molecular dynamics simulations
Authors: Aschi Massimiliano , Bozzi Argante , Di Bartolomeo Renato , Petruzzelli Raffaele
Published: May 2010

The main purpose of this work is to analyse, by means of molecular dynamics (MD) simulations both structural and mechanical‐dynamical differences between Hepcidin‐20 and Hepcidin‐25 in both oxidized and reduced states in aqueous solution. Results indicate that the presence of disulfide bonds is essential, in both peptides, for maintaining their β‐hairpin motif. As a matter of fact, the lack of this intra‐peptide covalent interactions produces an almost immediate deviation from the oxidized, plausibly active, structure in both the systems. Interestingly, reduced Hepcidin‐25 turns out to be characterized by a highly fluctuating structure which is found to rapidly span a large number of configurations at equilibrium. On the other hand, loss of disulfide bonds in the shorter peptide, results in a more compact and relatively rigid double‐turn structure. Comparison of mechanical–dynamical properties and sidechains–sidechains interactions in oxidized Hepcidin‐20 and Hepcidin‐25 strongly suggest also the key role of N‐terminus in the aggregation tendency of Hepcidin‐25. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 917–926, 2010.
Using non‐invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm–palladium catalyst
Authors: Beauregard D.A. , Yong P. , Macaskie L.E. , Johns M.L.
Published: May 2010

Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm–Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)(aq) is non‐paramagnetic while Cr(III)(aq) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non‐invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery. Biotechnol. Bioeng. 2010;107: 11–20. © 2010 Wiley Periodicals, Inc.
Optimal nitrogen supply as a key to increased and sustained production of a monoclonal full‐size antibody in BY‐2 suspension culture
Authors: Holland T. , Sack M. , Rademacher T. , Schmale K. , Altmann F. , Stadlmann J. , Fischer R. , Hellwig S.
Published: May 2010

Plant cell cultures have been used as expression hosts for recombinant proteins for over two decades. The quality of plant cell culture‐produced proteins such as full‐size monoclonal antibodies has been shown to be excellent in terms of protein folding and binding activity, but the productivity and yield fell short of what was achieved using mammalian cell culture, in which the key to gram‐per‐liter expression levels was strain selection and medium/process optimization. We carried out an extensive media analysis and optimization for the production of the full‐size human anti‐HIV antibody 2G12 inN. tabacumcv. BY‐2. Nitrogen source and availability was found to be one key factor for the volumetric productivity of plant cell cultures. Increased amounts of nitrate in the culture medium had a dramatic impact on protein yields, resulting in a 10–20‐fold increase in product accumulation through a combination of enhanced secretion and higher stability. The results were scalable from shake flasks to stirred‐tank bioreactors, where the maximum yield per cultivation volume was 8 mg L−1over 7 days. During the stationary phase, antibody levels were 150‐fold higher in nitrogen‐enriched medium compared to standard medium. The enhanced medium appeared not to affect antibody quality and activity, as determined by Western blots, surface plasmon resonance binding assays andN‐glycan analysis. Biotechnol. Bioeng. 2010;107: 278–289. © 2010 Wiley Periodicals, Inc.