bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen isotope analysis of phosphate: improved precision using TC/EA CF‐IRMS
Authors: LaPorte D. F. , Holmden C. , Patterson W. P. , Prokopiuk T. , Eglington B. M. 
Published: January 2009

AbstractOxygen isotope values of biogenic apatite have long demonstrated considerable promise for paleothermometry potential because of the abundance of material in the fossil record and greater resistance of apatite to diagenesis compared to carbonate. Unfortunately, this promise has not been fully realized because of relatively poor precision of isotopic measurements, and exceedingly small size of some substrates for analysis. Building on previous work, we demonstrate that it is possible to improve precision of δ18OPO4 measurements using a ‘reverse‐plumbed’ thermal conversion elemental analyzer (TC/EA) coupled to a continuous flow isotope ratio mass spectrometer (CF‐IRMS) via a helium stream [Correction made here after initial online publication]. This modification to the flow of helium through the TC/EA, and careful location of the packing of glassy carbon fragments relative to the hot spot in the reactor, leads to narrower, more symmetrically distributed CO elution peaks with diminished tailing. In addition, we describe our apatite purification chemistry that uses nitric acid and cation exchange resin. Purification chemistry is optimized for processing small samples, minimizing isotopic fractionation of PO4−3 and permitting Ca, Sr and Nd to be eluted and purified further for the measurement of δ44Ca and 87Sr/86Sr in modern biogenic apatite and 143Nd/144Nd in fossil apatite. Our methodology yields an external precision of ± 0.15‰ (1σ) for δ18OPO4. The uncertainty is related to the preparation of the Ag3PO4 salt, conversion to CO gas in a reversed‐plumbed TC/EA, analysis of oxygen isotopes using a CF‐IRMS, and uncertainty in constructing calibration lines that convert raw δ18O data to the VSMOW scale. Matrix matching of samples and standards for the purpose of calibration to the VSMOW scale was determined to be unnecessary. Our method requires only slightly modified equipment that is widely available. This fact, and the demonstrated improvement in precision, should help to make apatite paleothermometry far more accessible to paleoclimate researchers. Copyright © 2009 John Wiley & Sons, Ltd.
A spectroscopic approach to assess trace–heavy metal contents in contaminated floodplain soils via spectrally active soil components
Authors: Vohland Michael , Bossung Christian , Fründ Heinz‐Christian 
Published: January 2009

AbstractSoil samples from grassland plots in the Hase floodplain near Osnabrück (NW Germany) were analyzed using visible and near‐infrared laboratory spectroscopy (VNIRS) by means of an ASD FieldSpec II Pro FR‐ spectroradiometer (spectral range 0.4–2.5 µm), paralleled by atomic‐absorption spectrometry (AAS), automated combustion for Corg quantification, and texture analysis. By AAS, contents of Cu, Zn, and Pb were found to be clearly elevated which is due to industrial effluents into the river in the 19th and 20th century. As these heavy metals (HMs) cannot be assessed directly by VNIRS, it was one major task to clarify whether they can be quantified indirectly using intercorrelations with spectrally active soil components. A second goal was to identify the specific spectroscopic predictive mechanism which may also be applicable to assess trace‐HM contents of other soil samples similar to those investigated here. For the latter, Corg was found to be most indicative, whereas the binding of the metals to other constituents (Fe oxides, clay) was not utilizable in the spectroscopic approach. The measured spectra were subjected to a multiplicative scatter correction and afterwards used to establish partial least‐squares regression (PLSR) models to estimate the contents of the different soil constituents. For Corg, very reliable estimates were obtained for both calibration and validation samples (in the validation, r² amounted to 0.90 and the percentage root mean square error [RMSE] was equal to 30.6%). Estimation accuracies obtained by PLSR for the trace HMs were considerably lower (r² between 0.56 and 0.71, percentage RMSE > 50%), which can be traced back to moderate correlations with Corg as main spectral determinant. According to these results, VNIRS can be applied as rapid and precise screening method for Corg to complement traditional analytical methods and to be used efficiently for a large number of samples. The method of VNIRS may also be applied for an indirect estimation of Corg‐associated metals to address their spatial variability, for example. This issue appears to be of high importance for digital soil mapping by imaging spectroscopy on a local to medium spatial scale.
Determination of soil texture: Comparison of the sedimentation method and the laser‐diffraction analysis
Authors: Taubner Heidi , Roth Birgit , Tippkötter Rolf 
Published: January 2009

AbstractLaser‐diffraction analysis (LDA) is a rapid automated method achieving highly resolved frequency distributions of particle sizes. Recently, LDA has come into use in environmental sciences. However, in the size range of silt and clay deviations from the particle‐size analysis with the standard pipette method, which is regarded as the reference method for soil‐texture classification, have been reported. Therefore, this study concentrates (1) on the verification of systematic relations between both methods using a series of soils of Lower Saxony (Germany) and (2) on the general applicability of the laser‐diffraction method to soil‐texture classification as well as (3) texture‐based estimates of air capacity, available field capacity, and permanent wilting point.The comparison of LDA with the pipette method demonstrated highly significant linear correlations in each of the particle‐size fractions from clay to coarse silt. The slope of regressions ranged from 0.4 with fine silt to 3.1 with clay. If the clay content derived from LDA was applied to texture classification, the resulting textural classes differed from the standard textural classes, except for purely sandy samples with a clay content of <5%. However, the linear‐regression model enabled an approach of the LDA‐based clay content to values produced with the standard pipette method. Using this transformation, a texture classification became practicable in many cases, but, despite of a high significance level between LDA and pipette method, still led to wrong textural classes in several cases. A comparison with regression models from other regions in Europe showed both similarities and discrepancies, even for similar substrates. Hence, the laser‐diffraction analysis cannot be used for the texture classification of soil samples without verification by the standard pipette method.
Laser Micro Manufacturing
Authors: Gillner Arnold 
Published: January 2009

AbstractLaser processes have been used for specific manufacturing processes already since decades in applications, where conventional could not meet the demands on accuracy and flexibility. However, the share of micro applications within the whole laser market was always a minor one and laser cutting and welding are still dominating the laser application sector. Due to the increasing trend to miniaturization and higher integration of consumer products laser processes become more and more important and laser micro manufacturing is showing the highest market increase. This development is not only fostered by a strong market pull but also due to the availability of very high quality lasers, which allow the specific energy deposition on a micrometer scale at high processing speeds. Lower laser costs, easy installation and low maintenance costs have made lasers to a versatile tool for industrial micro manufacturing processes.
Power Is (Not) Everything
Authors: Mayerhofer Roland 
Published: January 2009

AbstractThe variety of different laser sources, either a brand new product or a derivate of already existing concepts is growing almost every day. Even an experienced application guy like me struggles more and more to find the appropriate laser for a specific application in the first shot. It is out of question, that it is more difficult for our customers who have not been so close to the evolution process of lasers, penetrating more and more areas of industrial production. Thus, this article is intended to give a broad overview on the fundamentals of laser material processing in order to help finding suitable laser properties for your application quickly. The influence of the most important parameter in laser material interaction, the amount of laser power, necessary for specific industrial applications is outlined.
The Midas Touch: Surface Processing With the UV Excimer Laser
Authors: Delmdahl Ralph , Paetzel Rainer 
Published: January 2009

AbstractVery much like the ancient king Midas who as the legend tells was able to transform ordinary material into gold by the touch of his hand, today's excimer lasers are capable of transforming an unspecificmaterial layer into a high value, functional surface by their unique beam properties.Representing today's most cost‐effective and dependable pulsed, ultraviolet (UV) laser technology, excimer lasers enable disruptive innovation in various growth industries as diverse as the markets for flat panel displays, automobiles, biomedical devices and alternative energies.It is the combination of two fundamental aspects, namely wavelength and output power, which determines the excimer laser's unique value adding potential in high tech industries which more than ever have to balance product size‐efficiency and performance demands with process speed and production costs. This article will try to provide an insight into some key applications of the excimer laser.
High Speed Processing for Microelectronics and Photovoltaics
Authors: Kauf Michael , Patel Raj , Bovatsek Jim 
Published: January 2009

AbstractQ‐switched infrared, green, UV and DUV lasers are being used routinely for various microelectronics and photovoltaic manufacturing applications, such as ablation and cutting of dielectric materials, LED scribe and cleave processes in microelectronics, and scribing thin film solar cells.To create functional good results when micromachining any material, the laser energy density needs to be set higher than the material removal threshold and a reasonable laser beam spot overlap is required. The maximum scribing speed achieved using a system with a pulsed laser source therefore is usually limited by the laser repetition rate and the energy per pulse available at that repetition rate. For a given repetition rate, as processing speed increases the beam spot overlap decreases and at certain critical processing speed laser beam spots gets separated in space and continuous scribing of material is not possible. This fundamental limitation has to be solved in order to achieve faster processing speeds, higher throughput, and lower cost per part.To overcome this limitation in next generation laser processing systems, SpectraPhysics has developed and evaluated high repetition rate mode‐locked lasers as an alternative to Q‐switched lasers. Using a high average power mode‐locked laser operating at 80 MHz, we have been able to demonstrate processing speeds that are an order of magnitude higher in thin layers of select materials than that with current Q‐switched technology. The following article reviews results obtained for micromachining dielectrics, scribing and cleaving blue LEDs, and scribing different solar cell materials.
Innovative Laser Materials Processing for Photovoltaics
Authors: Homburg Oliver , Harten Paul 
Published: January 2009

AbstractThere are several laser‐based processes which are currently used in solar cell manufacturing or show a high potential for being implemented in series production in the future. Among these are laser edge isolation, laser fired contacts, metal/emitter wrap through, laser doping as well as P1, P2 and P3 structuring of thin film solar cells. Currently, all these direct‐patterning processes are mostly performed by single‐mode lasers with Gaussian intensity distributions. In contrast, top hat profiles offer larger process stability as well as cost savings. Another process that is still in the research and development stage is the crystallization of amorphous Si into polycrystalline Si. Here an increase of the electron mobility results in a better separation of the charge carriers in the cell and finally increased cell efficiency. A novel diode laser line scanning system and first processing results are presented in this article.
Preparation of a Novel Polymer‐Modified Si Surface for DNA Immobilization
Authors: Demirel Gökçen Birlik , Coşkun Samet , Kalkan Meryem , Çaykara Tuncer 
Published: January 2009

AbstractThe design of a novel polymer‐modified overlayer composed of PPAPE and GPMS on a silicon wafer for immobilization of DNA molecules is described. After hydroxylation of Si(100) surfaces, GPMS molecules were self‐assembled onto these surfaces. PPAPE molecules were then covalently attached to the epoxy‐terminated surfaces. The incubation time and concentration of PPAPE was found to effect both layer thickness and water CA. The type of organic solvent and the pH were found to change the nature of the PPAPE‐modified surface for DNA immobilization. It is concluded that PPAPE‐modified surfaces show advantages for DNA immobilization by electrostatic interactions between DNA molecules and positively charged free amino groups of the PPAPE‐modified surfaces at the appropriate pH values.magnified image
Nickel‐Ion‐Mediated Control of the Stoichiometry of His‐Tagged Protein/Nanoparticle Interactions
Authors: De Mrinmoy , Rana Subinoy , Rotello Vincent M. 
Published: January 2009

AbstractThe interaction between synthetic materials and biomolecules plays an important role in biomedical and pathological sciences. An important issue in these interactions is control of stoichiometry. The interaction between NTA ligands and proteins with six consecutive His residues has been widely used for protein purification. Control of stoichiometry is an important issue in applying this recognition strategy to the creation of defined nanoparticle‐protein conjugates. In this communication we report the direct control of particle‐protein stoichiometry through variation of nickel chloride concentration, as demonstrated through fluorescence and gel electrophoresis.magnified image
A New Concept for More Biocompliant Bone Cements for Vertebroplasty and Kyphoplasty
Authors: Hu Xianbo , Zhai Xiaowen , Hirt Thomas 
Published: January 2009

AbstractA series of more biocompliant bone cements with mechanical properties that match those of different vertebral trabecular or cancellous bones for vertebroplasty and kyphoplasty applications, have been developed. The elastic modulus and strength of the bone cements are in a range of 5 to 400 MPa, and 5 to 75 MPa, respectively. The bone cement shows excellent thermal and dimensional stability in simulated body fluid of Ringer's solution at both 37 and 70 °C. The elastic modulus, strength, ultimate strain are constant over time at both temperatures and did not alter dimensions. The bone cement has a much lower exothermic temperature during polymerization compared with commercially available poly(methyl methacrylate) bone cements, and has high cohesiveness in liquid environments. It is able to be delivered through an 18 gauge needle ranging from 4 to 6 inches in length and reaches final mechanical properties within 30 min post delivery.magnified image
Photopolymerization without Photoinitiator of Bismaleimide‐Containing Oligo(oxypropylene)s: Effect of Oligoethers Chain Length
Authors: Vázquez Cuauhtémoc Pozos , Joly‐Duhamel Christine , Boutevin Bernard 
Published: January 2009

AbstractThis article describes the synthesis and characterization of a series of poly(propylene glycol bismaleimide) (PPGM) with molecular weights ($\overline M _{{\rm ws}}$) in the range of 390–2 600 g · mol−1. Their photopolymerization rates without photoiniator were similar to that of an acrylate resin in the presence of a photoinitiator. The reactivities and degrees of conversion of these PPGM oligomers, thermal and mechanical properties of the resulting materials were studied as a function of $\overline M _{\rm w}$. Rigid materials were obtained except for that containing the longest PPGM, which exhibited mechanical properties of a rubber. The glass transition temperature values and the thermal stability were found to decrease when $\overline M _{\rm w}$ of used oligomers was increased. Crosslinking density was the parameter that controlled both mechanical and thermal properties.magnified image
Thin Film Instabilities in Blends under Cylindrical Confinement
Authors: Chen Dian , Chen Jiun‐Tai , Glogowski Elizabeth , Emrick Todd , Russell Thomas P. 
Published: January 2009

AbstractRayleigh instabilities in bilayers of poly(methyl methacrylate) (PMMA) and polystyrene (PS) confined within the cylindrical nanoporous anodic aluminum oxide (AAO) membranes were investigated. The bilayered nanotubes were thermally annealed to induce phase separation and instabilities in the confined films. For short annealing times, the nanotubes were transformed into nanorods with periodic encapsulated air pockets. With longer annealing times, the air‐pockets coalesced to form columns of air. Small air inclusions encased in periodic domains of PS were, in turn, incorporated within PMMA nanorods. Selectively removing the PMMA by exposure to UV radiation and washing with acetic acid, left PS nanospheres with an air inclusion. Gold nanoparticles having PS ligands were also incorporated within the PS phase, generating novel composite morphologies.magnified image
Brain temperature and pH measured by 1H chemical shift imaging of a thulium agent
Authors: Coman Daniel , Trubel Hubert K. , Rycyna Robert E. , Hyder Fahmeed 
Published: January 2009

AbstractTemperature and pH are two of the most important physiological parameters and are believed to be tightly regulated because they are intricately related to energy metabolism in living organisms. Temperature and/or pH data in mammalian brain are scarce, however, mainly because of lack of precise and non‐invasive methods. At 11.7 T, we demonstrate that a thulium‐based macrocyclic complex infused through the bloodstream can be used to obtain temperature and pH maps of rat brain in vivo by 1H chemical shift imaging (CSI) of the sensor itself in conjunction with a multi‐parametric model that depends on several proton resonances of the sensor. Accuracies of temperature and pH determination with the thulium sensor – which has a predominantly extracellular presence – depend on stable signals during the course of the CSI experiment as well as redundancy for temperature and pH sensitivities contained within the observed signals. The thulium‐based method compared well with other methods for temperature (1H MRS of N‐acetylaspartate and water; copper–constantan thermocouple wire) and pH (31P MRS of inorganic phosphate and phosphocreatine) assessment, as established by in vitro and in vivo studies. In vitro studies in phantoms with two compartments of different pH value observed under different ambient temperature conditions generated precise temperature and pH distribution maps. In vivo studies in α‐chloralose‐anesthetized and renal‐ligated rats revealed temperature (33–34°C) and pH (7.3–7.4) distributions in the cerebral cortex that are in agreement with observations by other methods. These results show that the thulium sensor can be used to measure temperature and pH distributions in rat brain in vivo simultaneously and accurately with using biosensor imaging of redundant. Copyright © 2008 John Wiley & Sons, Ltd.
Aus Staub geboren. Planetenentstehung
Authors: Klahr Hubert , Henning Thomas 
Published: January 2009

AbstractDie Entdeckung von extrasolaren Planetensystemen hat die Theorie der Planetenentstehung vor neue Herausforderungen gestellt. Das grundlegende Modell zur Entstehung unseres Sonnensystems aus einer Staub und Gasscheibe um die junge Sonne besteht zwar unverändert seit der Mitte des letzen Jahrhunderts, es wurde jedoch im Laufe der Zeit um mehr und mehr Details bereichert. Auch heute sind noch viele Fragen offen, wie unser Sonnensystem oder die Planetensysteme um ferne Sterne entstanden sind.
Zylinder‐ und Kugelkreisel. Spielwiese
Authors: Ucke Christian , Schlichting Hans‐Joachim 
Published: January 2009

AbstractEin Zylinder führt bei geschicktem Anschnipsen eine komplizierte Kreiseldrehung aus. Besitzen Länge und Durchmesser ein ganzzahliges Verhältnis n, so erscheint eine Markierung auf dem einen Ende des Zylinders als n‐fach stehendes Muster. Dieser optische Effekt lässt sich mit einfachen Überlegungen an dem kreiselnden Zylinder erklären. In ähnlicher Weise kann man Kreisel aus zwei oder mehr zusammengefügten Kugeln bauen und ihre Bewegung physikalisch interpretieren.
Rutschen ohne Reibung
Authors: Schirmeisen André 
Published: January 2009

AbstractReibung ist allgegenwärtig, doch was passiert eigentlich genau, wenn zwei Oberflächen aneinander reiben? Ein deutsch‐amerikanisches Wissenschaftlerteam der Universität Münster und der Yale Universität untersuchten die grundlegenden Mechanismen der Reibung, indem sie Nanoteilchen über eine Oberfläche schoben. Überraschenderweise verschwand in einigen Fällen die Reibungskraft.
Protein in action gefilmt
Authors: Biehl Ralf , Richter Dieter 
Published: January 2009

AbstractPhysikern des Forschungszentrums Jülich ist es erstmals gelungen, Bewegungen in einem natürlichen, nicht modifizierten Protein räumlich und zeitlich aufgelöst zu messen. Anders als bisherige Methoden ermöglicht ihre Neutronenspinecho‐Spektroskopie die direkte Messung nicht nur der Schnelligkeit von inneren Bewegungen, sondern auch der räumlichen Ausdehnung und der dabei auftretenden inneren Kräfte.
Toughening effect of ethylene‐vinyl acetate rubber on nylon 1010 compatibilized by maleated ethylene‐vinyl acetate copolymers
Authors: Yu Haiyang , Zhang Yong , Ren Wentan 
Published: January 2009

AbstractThe toughening effect of ethylene‐vinyl acetate rubbers (EVM) with maleated ethylene‐vinyl acetate copolymers (EVA‐g‐MAH) on the nylon 1010 was investigated. The addition of 5 phr (per hundred nylon 1010) EVM increased the elongation at break of nylon 1010 to a great extent. The notched Izod impact strength of nylon/EVM blends increased with increasing EVM content. Scanning electron microscope showed that the EVM particle size was around 0.5 μm when the EVM content was 5 phr and increased with increasing EVM content. After the addition of EVA‐g‐MAH to nylon/EVM (100/20) blend, the average diameter of EVM particles decreased from more than 1 μm to 0.5–0.6 μm. EVA‐g‐MAH could improve the adhesion between nylon 1010 and EVM. A sharp brittle‐ductile transition (BDT) was observed when the interparticle distance was about 0.2 μm, independent of the addition of EVA‐g‐MAH. The notched Izod impact strength of nylon/EVM blends at low temperatures was measured and the BDT shifted toward low temperatures with increasing EVM or EVA‐g‐MAH content. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 434–444, 2009
Influence of RF Plasma Reactor Setup on Carboxylated Hydrocarbon Coatings
Authors: Körner Enrico , Fortunato Giuseppino , Hegemann Dirk 
Published: January 2009

AbstractFunctional hydrocarbon plasma polymer coatings were investigated using a low pressure RF plasma reactor. The deposition rate was examined for different CO2/C2H4 gas ratios and different power inputs at constant pressure. The CO2/C2H4 ratio can be used to tailor the functionality and the permanence of the plasma polymer coatings which is shown by XPS. The deposition of these plasma polymer coatings was compared in a symmetrical and asymmetrical setup of the reactor and discussed regarding energy input and plasma sheath potential for the varying plasma conditions. Furthermore, the influence of Ar admixture was examined in order to identify sputtering conditions by using an asymmetric Ag electrode. While a drop in the absolute deposition rate can be seen for Ar added in symmetrical conditions, the asymmetrical setup showed no noticeable differences.magnified image