bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractMgH2 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

AbstractTo 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

AbstractTemperature‐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

AbstractFluorescence 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

AbstractPolytetrafluoroethylene (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

AbstractDegradation 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

AbstractFluorous 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

AbstractObjectiveMidlife 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.MethodsParticipants 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.ResultsIn 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.InterpretationIn 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

AbstractThe 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

AbstractPossible 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

AbstractMeasuring 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

AbstractQuantitative 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

AbstractIn 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

AbstractThe 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

AbstractHigh‐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

AbstractLyα 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

AbstractThe 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)