bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid chromatography at the critical condition: Thermodynamic significance and influence of pore size
Authors: Abdulahad Asem I. , Ryu Chang Y. 
Published: November 2009

AbstractLiquid chromatography at the critical condition (LCCC) is a high performance liquid chromatography (HPLC) technique that lies between size exclusion chromatography and adsorption‐based interaction chromatography, where the elution of polymers becomes independent of polymer molecular weight. At LCCC, the balance between the entropic exclusion and the enthalpic adsorption interactions between polymers and stationary phases results in the simultaneous HPLC elution of polymers regardless of molecular weight. Using C18‐bonded silica chromatographic columns with 5 μm particle size and different average pore size (diameter = 300 Å, 120 Å, 100 Å, and 50 Å), we report (1) the thermodynamic significance of LCCC conditions and (2) the influence of column pore size on the determination of critical conditions for linear polymer chains. Specifically, we used mixtures of monodisperse polystyrene samples ranging in molecular weight from 162 to 371,100 g/mol and controlled the temperature of the HPLC columns at a fixed composition of a mobile phase consisting of 57(v/v)% methylene chloride and 43(v/v)% acetonitrile. It was found that, at the fixed mobile phase composition, the temperature of LCCC (TLCCC) is higher for C18‐bonded chromatographic columns with larger average pore size. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2533–2540, 2009
A Monte Carlo study of the coil‐to‐globule transition of model polymer chains near an attractive surface
Authors: Rissanou Anastassia N. , Anastasiadis Spiros H. , Bitsanis Ioannis A. 
Published: November 2009

AbstractWhen a polymer chain in solution interacts with an atomically smooth solid substrate, its conformational properties are strongly modified and deviate substantially from those of chains in bulk. In this work, the interplay of two competing transitions that affect the conformations of polymer chains near an energetically attractive surface is studied by means of Monte Carlo simulations on a cubic lattice. The transition from an extended to a compact conformation of a polymer chain near an attractive wall, as solubility deteriorates, exhibits characteristics akin to the “coil‐to‐globule” transition in bulk. An effective θ‐temperature is determined. Its role as the transition point is confirmed in a variety of ways. The nature of the coil‐to‐compact transition is not qualitatively different from that in the bulk. Adsorbed polymer chains may assume “globular” or “pancake” configurations depending on the competition among adsorption strength, cohesive energy, and entropy. In a very relevant range of conditions, the dependence of the adsorbate thickness on chain‐length is intermediate between that of 3‐d (“semidroplets”) and 2‐d (“pancake”) objects. The focus of this study is on rather long polymer chains. Several crucial features of the transitions of the adsorbed chains areN‐dependent and various aspects of the adsorption and “dissolution” process are manifested clearly only at the “long chain” limit. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2462–2476, 2009
Monte Carlo studies of tethered chains
Authors: Karaiskos Emmanuel , Bitsanis Ioannis A. , Anastasiadis Spiros H. 
Published: November 2009

AbstractMonte Carlo computer simulations of end‐tethered chains grafted onto a hard wall have been performed. The chains were modeled as self‐avoiding chains on a cubic lattice at athermal solvent conditions. The simulations spanned a wide range of chain lengths, N (100–1000, i.e., up to molecular weights of a few hundred thousands), and anchoring densities, σ (2 × 10−4 to 0.4), to properly chart the relevant parameter space. It is shown that the reduced surface coverage σ* = σπR is the most appropriate variable that quantitatively determines the mushroom, overlapping mushroom and brush regimes, where Rg is the radius of gyration of a free chain in solution. The simulation data are analyzed to determine the conformational characteristics and shape of the anchored chains and to compare them with the predictions of the analytical self consistent field theory. The strong stretching limit of the theoretical predictions is obtained only for σ* > 8. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47:2449–2461, 2009
Elimination of Homo‐polypeptides of Amino Acids from Surfaces by means of Low Pressure Inductively Coupled Plasma Discharge
Authors: Kylián Ondřej , Rauscher Hubert , Denis Benjamin , Ceriotti Laura , Rossi François 
Published: November 2009

AbstractThe action of low‐pressure inductively coupled plasma discharge on selected homo‐polypeptides of amino acids, i.e., fundamental building blocks of proteins, has been investigated in order to evaluate their removal rates under different treatment conditions. It has been found that the removal rates of the homo‐polypeptides studied are strongly linked to the composition of the plasma discharges, but they are almost insensitive to their chemical composition. This provides an indication that all proteins could be removed at similar rates by a given plasma discharge, which is a finding of paramount importance mainly with respect to decontamination of surfaces and elimination of infectious proteins like prions.magnified image
The Morphology and Mechanical Properties of Polycarbonate/Acrylonitrile Butadiene Styrene Modified by Ar Ion Beam Irradiation
Authors: Ahmed Sk. Faruque , Yi Jin Woo , Moon Myoung‐Woon , Jang Yong‐Jun , Park Bong‐Hyun , Lee Seong‐Hoon , Lee Kwang‐Ryeol 
Published: November 2009

AbstractThis study examined the surface morphological evolution of polycarbonate and acrylonitrile butadiene styrene (PC/ABS) irradiated with an Ar ion beam using an ion beam system. PC was not affected by the Ar ion beam treatment at a lower ion beam treatment times but the ABS portion formed a foam‐like nanostructure at the surface. On the other hand, both PC and ABS formed nanostructures with length of 100 to 120 nm and a mean diameter of ≈35 nm at longer beam treatment times. The Raman and FTIR spectra revealed polymer chain scissioning. Nanoindentation showed that the hardness and elastic modulus of the PC/ABS decreases from 0.22 to 0.18 GPa and from 3.39 to 2.98 GPa, respectively with increasing Ar ion beam treatment time due to the surface nano‐structures formed by Ar ion beam.magnified image
Plasma‐Induced Direct‐Grafting on Polytetrafluoroethylene Films by Quasi‐Glow Discharge at Atmospheric Pressure
Authors: Wan Jun , Wang Shouguo , Song Mingwei , Jia Xianghong , Yang Jinghua 
Published: November 2009

AbstractStructurally well‐defined poly(acrylic acid)s have been direct‐grafted on polytetrafluoroethylene (PTFE) films by a quasi‐glow discharge (QGD) using argon and acrylic acid. X‐ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy provided obvious evidence for a high retention of the carboxylic acid group on PTFE surface, up to 77.5% of all carboxylic acid functional group. Optical emission spectroscopy (OES) indicated that polymerization proceeds predominantly via an opening of the CC bonds. The modified PTFE films were found to exhibit low water contact angle values and good ageing behavior. The mechanisms of plasma‐induced direct‐graft polymerization of acrylic acid on PTFE films were discussed combining with the real‐time electrical and optical diagnostics of the QGD plasma.magnified image
Construction of human monoclonal single‐chain Fv antibodies against small‐cell lung cancer by phage display libraries derived from cell‐immunized SCID mice engrafted with human peripheral blood lymphocytes
Authors: Douguchi Junya , Hashiguchi Akinori , Sakamoto Michiie 
Published: November 2009

AbstractIn this study, we describe a phage display strategy to obtain human monoclonal single‐chain Fv (scFv) antibodies binding target cancer cell surface proteins. By developing a cancer cell immunization protocol for SCID mice engrafted with human peripheral blood lymphocytes in combination with an antibody phage display method, we have isolated phage antibodies binding small‐cell lung cancer cell line H889 by subtractive selection. One of the isolated scFv antibodies, 12EAb, recognized the E2 component of pyruvate dehydrogenase complex (PDC‐E2) by immunoprecipitation according to MALDI‐TOF MS analysis. Furthermore, we have confirmed the plasma membrane localization of PDC‐E2 in small‐cell lung cancer cells by immunocytochemistry and cell surface protein biotinylation, although PDC‐E2 is usually located in the mitochondrial matrix. These results, including unique localization of identified antigens, were obtained by proteomic approaches. The present methods can be applied to generate human monoclonal scFv antibodies against tumor cells and to identify new molecular targets for immunotherapy and markers for diagnosis.
Study of TATP: Influence of Reaction Conditions on Product Composition
Authors: Matyáš Robert , Pachman Jiri 
Published: November 2009

AbstractThe influence of reaction conditions (temperature, catalyst type, catalyst concentration – represented as molar ratio catalyst/acetone nc/na) on the composition of the product formed from the reaction of acetone and hydrogen peroxide (30%) under acid catalysis was studied. 3,3,6,6,9,9‐Hexamethyl‐1,2,4,5,7,8‐hexoxonane (TATP) was found to be the major product when the content of the catalyst in the reaction mixture is low (nc/na ≤ 0.5). A single side product (peak 10.2) in an amount ranging from 1.5 to 8% of the total peak area was present in all the prepared samples. Three other side products were found when catalyzing by hydrochloric and nitric acids. Temperature and catalyst type did not have a significant influence on the composition of the product at low catalyst concentration. Increasing the catalyst concentration led to the formation of 3,3,6,6‐tetramethyl‐1,2,4,5‐tetroxane (DADP) either as a co‐product of TATP or as an exclusive product depending on the concentration of the catalyst.
Replication of prostate cancer risk loci on 8q24, 11q13, 17q12, 19q33, and Xp11 in African Americans
Authors: Hooker Stanley , Hernandez Wenndy , Chen Hankui , Robbins Christiane , Torres Jada Benn , Ahaghotu Chiledum , Carpten John , Kittles Rick A. 
Published: November 2009

AbstractBACKGROUNDProstate cancer (Pca) is a common malignancy that disproportionately affects African American men (AA). Recently there have been several genome‐wide association studies (GWAS) implicating new prostate cancer risk loci along chromosomes 2, 3, 6, 7, 8, 10, 11, 12, 17, 19, and X in populations of European ancestry. Given the higher incidence and mortality for AAs, and differences in allele frequencies and haplotype structures between African and European descent populations, it is important to assess the impact of these candidate risk loci in AAs.METHODSHere we evaluated 20 single nucleotide polymorphisms (SNPs) associated with prostate cancer risk in recent GWAS studies, in AA prostate cancer cases and controls.RESULTSWe replicated five of the SNPs in our AA population, rs10896449 on 11q13.2 (P = 0.009), rs2735839 on 19q33.33 region, (P = 0.04), rs443076 on chromosome 17q12 (P = 0.008), rs5945572 on Xp11.22 (P = 0.05), as well as the rare variant specific to west African ancestry, bd11934905 in region 2 of 8q24 (P = 1 × 10−4).CONCLUSIONSWhile we were able to replicate a few of the previous GWAS SNPs, we were not able to confirm the vast majority of these associations in our AA population. This finding further supports the need to perform GWAS and additional fine mapping in AAs to locate additional susceptibility loci. Prostate 70: 270–275, 2010. © 2009 Wiley‐Liss, Inc.
Chimeric adenoviral vectors incorporating a fiber of human adenovirus 3 efficiently mediate gene transfer into prostate cancer cells
Authors: Murakami Miho , Ugai Hideyo , Belousova Natalya , Pereboev Alexander , Dent Paul , Fisher Paul B. , Everts Maaike , Curiel David T. 
Published: November 2009

AbstractBACKGROUNDWe have developed a range of adenoviral (Ad) vectors based on human adenovirus serotype 5 (HAdV‐5) displaying the fiber shaft and knob domains of species B viruses (HAdV‐3, ‐11, or ‐35). These species B Ads utilize different cellular receptors than HAdV‐5 for infection. We evaluated whether Ad vectors displaying species B fiber shaft and knob domains (Ad5F3Luc1, Ad5F11Luc1, and Ad5F35Luc1) would efficiently infect cancer cells of distinct origins, including prostate cancer.METHODSThe fiber chimeric Ad vectors were genetically generated and compared with the original Ad vector (Ad5Luc1) for transductional efficiency in a variety of cancer cell lines, including prostate cancer cells and primary prostate epithelial cells (PrEC), using luciferase as a reporter gene.RESULTSProstate cancer cell lines infected with Ad5F3Luc1 expressed higher levels of luciferase than Ad5Luc1, as well as the other chimeric Ad vectors. We also analyzed the transductional efficiency via monitoring of luciferase activity in prostate cancer cells when expressed as a fraction of the gene transfer in PrEC cells. In the PC‐3 and DU145 cell lines, the gene transfer ratio of cancer cells versus PrEC was once again highest for Ad5F3Luc1.CONCLUSIONOf the investigated chimeric HAdV‐5/species B vectors, Ad5F3Luc1 was judged to be the most suitable for targeting prostate cancer cells as it showed the highest transductional efficiency in these cells. It is foreseeable that an Ad vector incorporating the HAdV‐3 fiber could potentially be used for prostate cancer gene therapy. Prostate 70: 362–376, 2010. © 2009 Wiley‐Liss, Inc.
Spatial decorrelation of the conductive nanotube network in a polymer melt
Authors: Lellinger Dirk , Skipa Tetyana , Böhm Wolfgang , Alig Ingo 
Published: November 2009

AbstractTime resolved electrical conductivities of a polycarbonate (PC) composite melt filled with multiwalled carbon nanotubes (MWNTs) were measured in a rheometer equipped with ring electrodes. Strain was applied to the melt in trapezoidal shape, i.e., as a first positive shear pulse, followed by a pause of varying duration, and finally a negative shear pulse was applied. It is well known that applying shear to a conductive melt containing nanotubes causes a conductivity decrease due to the destruction of the nanotube network during shear. This effect should be independent on the direction of shear. However, if there was only a short pause between positive and negative shear pulses, one observes an increase of conductivity during the negative shear pulse. For longer pauses, this effect diminishes, and finally, the expected conductivity decrease can be seen. The effect will be explained by the spatial de‐correlation of the nanotubes related to their agglomeration in the melt during the pause. Normalized conductivity of polycarbonate melt with MWNT during the negative shear pulse for varying duration of the pause between positive and negative shear.
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Peapod synthesis depending on the number of nanotube sidewalls
Authors: Spudat C. , Meyer C. , Goss K. , Schneider C. M. 
Published: November 2009

AbstractIn this paper we demonstrate filling of carbon nanotubes (CNTs) grown by chemical vapor deposition (CVD) directly on Si3N4 TEM grids. The CNTs are synthesized at different growth temperatures TCVD providing different numbers of sidewalls and diameters. We characterize each step of the peapod synthesis and focus on the opening of as‐grown CNTs, which is necessary for filling them with guest molecules like C60. Thus, the creation of defects during peapod synthesis and the resulting peapods are studied using high resolution TEM and Raman spectroscopy.
The thermodynamic stability and simulated STM images of graphene nanoribbons
Authors: Wassmann T. , Seitsonen A. P. , Saitta A. M. , Lazzeri M. , Mauri F. 
Published: November 2009

AbstractIn this study, we investigated the edge formation energy of hydrogen‐terminated graphene nanoribbons as a function of the chemical potential of the environment as well as their electronic and magnetic properties by means of density functional theory. The single‐hydrogen‐terminated zigzag ribbons, well known for their antiferromagnetic edge states, were found to be stable only under extremely low vacuum pressures. At more standard conditions, the most stable structures are the single‐ and double‐hydrogenated armchair edges and a zigzag edge configuration with one double‐ and two single‐hydrogenated sites. At high hydrogen pressure, the edge formation energy becomes negative, meaning that graphene spontaneously breaks into ribbons. Clar type bond formulas proved to be an excellent tool for the rationale behind the stability, existence of edge states, and appearance of magnetism, and they are in perfect agreement with simulated scanning tunneling microscope (STM) images of the ribbons.Bond formulas and simulated STM images show an identical pattern of Clar sextets. Left: single‐hydrogen‐terminated armchair ribbon. Right: double‐hydrogen‐terminated armchair ribbon. U = −0.5 V, sample–tip distance fixed at 3 Å.
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Electronic and optical properties of alkali metal doped carbon nanotubes
Authors: Kramberger Christian , Rauf Hendrik , Knupfer Martin , Shiozawa Hidetsugu , Batchelor David , Kataura Hiromichi , Pichler Thomas 
Published: November 2009

AbstractMacroscopic samples of single wall carbon nanotubes (SWNT) are a nano meshed composite of interacting semiconducting and metallic nanotubes. They are a showcase example to study molecular semiconductor/metal interfaces, which are of fundamental relevance for molecular electronics and device architecture. Potassium intercalation of mixed bundles of SWNT offers facile means to tickle the delicate balance of internal charge transfer and Fermi level pinning in these systems. Moreover, the effective dimensionality of the metallic phase can be tailored from a Tomonaga–Luttinger liquid in one‐dimensional channels to a bulk Fermi liquid.
Morphological and electrical changes in TiO2 memristive devices induced by electroforming and switching
Authors: Münstermann Ruth , Yang J. Joshua , Strachan John Paul , Medeiros‐Ribeiro Gilberto , Dittmann Regina , Waser Rainer 
Published: November 2009

AbstractCombining delamination technique with conductive AFM, we have been able to reveal spatially resolved morphology and conductance changes in TiO2 memristive junctions after electroforming and switching. Being able to distinguish between effects caused by electroforming and switching, respectively, we could demonstrate that electroforming results in the creation of localized conductance channels induced by oxygen evolution while subsequent resistive switching causes an additional conducting structure next to the forming spot. We observe that the lateral extent of this structure depends on the number of switching cycles indicating an ongoing breaking of existing and creation of neighbouring current channels during subsequent switching. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On‐line solid‐phase extraction coupled with liquid chromatography/electrospray ionization mass spectrometry for the determination of trace tributyltin and triphenyltin in water samples
Authors: Sun Qian , Chen Zuliang , Yuan Dongxing , Megharaj Mallavarapu , Naidu Ravendra 
Published: November 2009

AbstractOn‐line solid‐phase extraction (SPE) for pre‐concentration and sample cleanup is one strategy to reduce matrix effects and to simultaneously improve detection sensitivity in liquid chromatography/mass spectrometry (LC/MS). This paper describes an on‐line SPE‐LC/MS method for the determination of tributyltin (TBT) and triphenyltin (TPhT) at trace levels in water samples. The direct coupling of an on‐line C18 pre‐column to LC/MS was used to pre‐concentrate TBT and TPhT at trace levels from waters and to remove interfering matrix effects. Pre‐concentration was followed by separation of TBT and TPhT on a C18 column using a mobile phase containing 0.1% (v/v) HCOOH/5 mM HCOONH4 and methanol. While both electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) can be interfaced with MS for the detection of TBT and TPhT, ESI‐MS was preferred for this application. The calibration curve for the targets was linear in the concentration range 0.1–30 µg L−1. The detection limit (signal‐to‐noise (S/N) ratio = 3) was 0.02 µg L−1 when 3.0 mL of sample was enriched on the C18 pre‐column. The recoveries of TBT and TPhT in spiked waters were from 81.0 to 101.9%. The reproducibilities for the analysis of the standard mixture (10 µg L−1) for TBT and TPhT were 13.1 and 5.0%, respectively. The developed method was an easy and fast way to analyze TBT and TPhT in water samples. Copyright © 2009 John Wiley & Sons, Ltd.
Attending to student epistemological framing in a science classroom
Authors: Hutchison Paul , Hammer David 
Published: November 2009

AbstractStudies of learning in school settings indicate that many students frame activities in science classes as the production of answers for the teacher or test, rather than as making new sense of the natural world. A case study of an episode from a class taught by the first author demonstrates what productive and unproductive student framing can look like in a science classroom. The case study demonstrates how some student activity commonly seen as undesirable may be evidence of productive framing, and activity commonly viewed as desirable may be seen as evidence of unproductive framing. © 2009 Wiley Periodicals, Inc. Sci Ed 94:506–524, 2010
Governance, ownership structure, and performance of IPO firms: the impact of different types of private equity investors and institutional environments
Authors: Bruton Garry D. , Filatotchev Igor , Chahine Salim , Wright Mike 
Published: November 2009

AbstractThis paper examines performance effects of ownership concentration and two types of private equity investors (venture capitalists and business angels) in firms that have recently undergone an initial public offering (IPO) in the United Kingdom and France. We expand and contextualize nascent understanding of multiple agency theory by examining heterogeneity of private equity investors and by suggesting that multiple agency relationships are affected by different institutional contexts. We employ a unique, hand‐collected dataset of 224 matched IPOs (112 in each country). Controlling for the endogeneity of private equity investors' retained share ownership, we find support for the agency theory argument that concentrated ownership improves IPOs' performance. The research also shows that the two types of private equity investors have a differential impact on performance, and the legal institutions in a given country moderate this impact. Copyright © 2009 John Wiley & Sons, Ltd.