bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Van der Pauw method for sheet resistance measurements of polypyrrole‐coated para‐aramide woven fabrics
Authors: Banaszczyk J. , Schwarz A. , De Mey G. , Van Langenhove L. 
Published: April 2010

AbstractIn this article, it is shown that the Van der Pauw (VDP) method, generally known in microelectronics, can be successfully adapted to sheet resistance measurements of electroconductive fabrics. We prepared two polypyrrole‐coated woven para‐aramide fabrics and used a simple setup to measure their sheet resistances. The results were then compared with those obtained using a sophisticated commercial collinear array probe. The measurements were done in a 1 month interval, to investigate the influence of the coating aging on the sheet resistance of the samples. The influence of the contact positioning on the accuracy of the VDP measurement was investigated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Tumor necrosis factor α blockers and malignancy in children: Forty‐eight cases reported to the food and drug administration
Authors: Diak Peter , Siegel Jeffrey , La Grenade Lois , Choi Lauren , Lemery Steven , McMahon Ann 
Published: April 2010

AbstractObjectiveMalignancies reported in children using tumor necrosis factor α (TNFα) blockers have raised concerns of a potential increased risk. This study was undertaken to investigate postmarketing reports of malignancy in children treated with TNF blockers.MethodsThe FDA's Adverse Event Reporting System was searched to identify malignancies associated with the use of infliximab, etanercept, and adalimumab in children in whom therapy was initiated between the ages of 0 and 18 years. The reporting rates for infliximab and etanercept were compared with the background rate of malignancy in the general pediatric population.ResultsForty‐eight reports of malignancy in children were identified: 31 following infliximab use, 15 following etanercept use, and 2 following adalimumab use. Half of the malignancies reported were lymphomas and included both Hodgkin's and non‐Hodgkin's lymphoma. The remaining reported cases involved a variety of different malignancies including leukemia, melanoma, and solid organ cancers. The majority of the reported cases (88%) involved the concomitant use of other immunosuppressants. Reporting rates for malignancy showed that infliximab had a consistently higher reporting rate when compared with background rates in the general pediatric population for lymphomas and all malignancies. The reporting rates for etanercept were elevated above background for lymphomas and were on par with background for all malignancies.ConclusionThere is evidence that treatment with TNF blockers in children may increase the risk of malignancy. However, the cases were confounded by the potential risk of malignancy associated with underlying illnesses and the use of concomitant immunosuppressants; therefore, a clear causal relationship could not be established.
Biofuels in China: past, present and future
Authors: Zhong Cheng , Cao Ying‐Xiu , Li Bing‐Zhi , Yuan Ying‐Jin 
Published: April 2010

AbstractEnergy security and environmental stress force China to seek and develop biofuels as a substitute of fossil energy. Meanwhile, China has great potential to provide a large quantity of feedstocks for biofuel production due to its vast amount of non‐food crops, such as tuberous crops, sweet sorghum, cellulosic biomass, and algae. Recently, the study and the industrial‐scale production of biofuels, particularly, fuel ethanol and biodiesel, have progressed remarkably in China as a result of government preferential policies and funding supports. We have briefly reviewed the historical development of biofuels in China with special emphasis on current feedstock utilization and process technology development. The bottlenecks of utilizing various feedstocks have also been analyzed and the prospects for future biofuel development in China have been explored. Biorefineries integrating reliable, low‐cost and sufficient non‐food feedstock supplies with highly efficient, environmentally friendly process technologies could sustain a bright future for biofuel development in China. Copyright © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd
Evaluation of alternatives for human lysozyme purification from transgenic rice: Impact of phytic acid and buffer
Authors: Wilken Lisa R. , Nikolov Zivko L. 
Published: April 2010

AbstractProducing economically competitive recombinant human lysozyme from transgenic rice demands an inexpensive purification process for nonpharmaceutical applications. Human lysozyme is a basic protein, and thus, cation exchange chromatography was the selected method for lysozyme purification. Similar to other protein production systems, the identification of critical impurities in the rice extract was important for the development of an efficient purification process. Previous adsorption data indicated that phytic acid was probably responsible for an unacceptably low cation exchange adsorption capacity. In this study, we confirm that reducing phytic acid concentration improves lysozyme binding capacity and investigate alternative process conditions that reduce phytic acid interference. Compared with the previous best process, the adsorption capacity of human lysozyme was increased from 8.6 to 19.7 mg/mL when rice extract was treated with phytase to degrade phytic acid. Using tris buffer to adjust pH 4.5 extract to pH 6 before adsorption reduced phytic acid interference by minimizing phytic acid‐lysozyme interactions, eliminated the need for phytase treatment, and increased the binding capacity to 25 mg/mL. Another method of reducing phytic acid concentration was to extract human lysozyme from rice flour at pH 10 with 50 mM NaCl in 50 mM sodium carbonate buffer. A similar binding capacity (25.5 mg/mL) was achieved from pH 10 extract that was clarified by acidic precipitation and adjusted to pH 6 for adsorption. Lysozyme purities ranged from 95 to 98% for all three processing methods. The tris‐mediated purification was the most efficient of the alternatives considered. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Effect of the usage of wikis on an educational context
Authors: Abreu Pedro , Castro Silva Daniel , Mendes Pedro , Vinhas Vasco 
Published: April 2010

AbstractThe use of wiki tools in personal and professional contexts has increased in the past years. This article provides an overview on recent developments of wiki technologies, and tries to determine their acceptance level in an academic environment. Also, suggestions are presented that may influence future developments in this area. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 646–653, 2012
Optical coefficient‐based multivariate calibration on near‐infrared spectroscopy
Authors: Shi Zhenqi , Cogdill Robert P. , Martens Harald , Anderson Carl A. 
Published: April 2010

AbstractThe time and expense of calibration development limit the feasibility of NIR spectroscopy for many industrial applications, with a major portion of the costs being related to creation of a sufficient set of calibration samples. Net analyte signal (NAS) and generalized least squares (GLS) pre‐processing have been proposed in the literature as methods to simplify multivariate calibration by reducing the quantity of calibration samples by orthogonalizing or shrinking interference signals. Synthetic calibration has also been reported as a method to combine interference signals with pure component spectra to generate virtual calibration models, thereby reducing the number of real calibration samples required. The goals of this paper were to (1) compare theoretical and practical differences between NAS and GLS pre‐processing and (2) explore the potential of simplified NIR calibrations, both empirical and synthetic, constructed using optical coefficient‐based signal processing on predicting chemical compositions of pharmaceutical powder mixtures. A reduced calibration dataset including only one pharmaceutical powder mixture composition and pure component spectra was used for both empirical and synthetic calibrations. Absorption and reduced scattering coefficients, obtained from spatially‐resolved spectroscopy, were used herein as interference signals in NAS/GLS pre‐processing for both calibrations. As a result, NAS and GLS were shown to be equivalent in both theoretical and practical senses. After optical coefficient‐based signal processing, simplified calibrations, both empirical and synthetic, were demonstrated to have similar model performance as generic pre‐processing methods such as SNV and derivative, while requiring fewer principal components and achieving a lower prediction error. Copyright © 2010 John Wiley & Sons, Ltd.
Computational performance and cross‐validation error precision of five PLS algorithms using designed and real data sets
Authors: Martins João Paulo A. , Teófilo Reinaldo F. , Ferreira Márcia M. C. 
Published: April 2010

AbstractAn evaluation of computational performance and precision regarding the cross‐validation error of five partial least squares (PLS) algorithms (NIPALS, modified NIPALS, Kernel, SIMPLS and bidiagonal PLS), available and widely used in the literature, is presented. When dealing with large data sets, computational time is an important issue, mainly in cross‐validation and variable selection. In the present paper, the PLS algorithms are compared in terms of the run time and the relative error in the precision obtained when performing leave‐one‐out cross‐validation using simulated and real data sets. The simulated data sets were investigated through factorial and Latin square experimental designs. The evaluations were based on the number of rows, the number of columns and the number of latent variables. With respect to their performance, the results for both simulated and real data sets have shown that the differences in run time are statistically different. PLS bidiagonal is the fastest algorithm, followed by Kernel and SIMPLS. Regarding cross‐validation error, all algorithms showed similar results. However, in some situations as, for example, when many latent variables were in question, discrepancies were observed, especially with respect to SIMPLS. Copyright © 2010 John Wiley & Sons, Ltd.
Red‐NIR Luminescent Hybrid Poly(methyl methacrylate) Containing Covalently Linked Octahedral Rhenium Metallic Clusters
Authors: Molard Yann , Dorson Frederick , Brylev Konstantin A. , Shestopalov Michael A. , Le Gal Yann , Cordier Stéphane , Mironov Yuri V. , Kitamura Noboru , Perrin Christiane 
Published: April 2010

AbstractThe embedding of functional inorganic entities into polymer matrices has become an intense field of investigation in which the main challenges are to keep the added value of the inorganic entities while preventing their self‐aggregation within the organic matrix. We present a simple way to obtain a homogeneous highly red‐NIR luminescent hybrid copolymer that contains covalently bonded nanometric‐sized {Re6} octahedral clusters. The [Re6Sei8(OH)a6]4− cluster complexes are primarily functionalized in two steps with tert‐butylpyridine (TBP) and methacrylic acid (MAC) to give neutral [Re6Se8(TBP)4(MAC)2] building blocks that are copolymerized with methyl methacrylate (MMA) either in solution or in bulk in the presence of azobisisobutyronitrile as an initiator. Several samples containing 0, 0.025, 0.05, and 0.1 wt % of functionalized {Re6} clusters were prepared. As the {Re6} cluster/MMA ratio is very low, the obtained copolymers keep the entire processability of pure poly(methyl methacrylate) (PMMA), as demonstrated by differential scanning calorimetry and thermogravimetric analysis. Voltammetric and luminescence studies also indicate that the intrinsic properties of the clusters are preserved within the polymer matrix. All the samples show a bright (emission quantum yield=0.07), broad, and structureless emission band, which extends from λ=600 nm to more than λ=950 nm, with the maximum wavelength centered around λem=710 nm either in solution or in the solid state. Moreover, the high stability of the incorporated inorganic phosphors prevents the material from photobleaching, and thus the luminescence properties are kept entirely even after nine months of ageing.
A Spirocyclohexyl Nitroxide Amino Acid Spin Label for Pulsed EPR Spectroscopy Distance Measurements
Authors: Rajca Andrzej , Kathirvelu Velavan , Roy Sandip K. , Pink Maren , Rajca Suchada , Sarkar Santanu , Eaton Sandra S. , Eaton Gareth R. 
Published: April 2010

AbstractSite‐directed spin labeling and EPR spectroscopy offer accurate, sensitive tools for the characterization of structure and function of macromolecules and their assemblies. A new rigid spin label, spirocyclohexyl nitroxide α‐amino acid and its N‐(9‐fluorenylmethoxycarbonyl) derivative, have been synthesized, which exhibit slow enough spin‐echo dephasing to permit accurate distance measurements by pulsed EPR spectroscopy at temperatures up to 125 K in 1:1 water/glycerol and at higher temperatures in matrices with higher glass transition temperatures. Distance measurements in the liquid nitrogen temperature range are less expensive than those that require liquid helium, which will greatly facilitate applications of pulsed EPR spectroscopy to the study of structure and conformation of peptides and proteins.
Group 13 Ligand Supported Heavy‐Metal Complexes: First Structural Evidence for Gallium–Lead and Gallium–Mercury Bonds
Authors: Prabusankar Ganesan , Gemel Christian , Winter Manuela , Seidel Rüdiger W. , Fischer Roland A. 
Published: April 2010

AbstractHeavy‐metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC6H3‐2,6‐iPr2)2, 2‐diisopropylphenylamino‐4‐diisopropyl phenylimino‐2‐pentene) with corresponding metal precursors. The reaction of Me3PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe3] (1) composed of GaPbIV bonds. In addition, the monomeric plumbylene‐type compound [{(ddp)Ga(OSO2CF3)}2Pb(thf)] (2 a) with an unsupported Ga‐PbII‐Ga linkage was obtained by the reaction of [Pb(OSO2CF3)3] with Ga(ddp) (2 equiv). Compound 2 a falls under the rare example of a discrete plumbylene‐type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO2CF3)3]⋅2 H2O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(μ‐OSO2CF3)}2(OH2)Pb] (2 b) at below −10 °C. Compound 2 b consists of a bent Ga‐Pb‐Ga backbone with a bridging triflate group between the GaPb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC6F5) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti‐[{(ddp)Ga(SC6F5)}2Hg] (3 a) and gauche‐[{(ddp)Ga(SC6F5)}2Hg] (3 b), respectively, with a linear Ga‐Hg‐Ga linkage. Compounds 1–3 were structurally characterized and these are the first examples of compounds comprised of GaPbII, GaPbIV, and GaHg bonds.
Binuclear Terbium(III) Complex as a Probe for Tyrosine Phosphorylation
Authors: Akiba Hiroki , Sumaoka Jun , Komiyama Makoto 
Published: April 2010

AbstractBy using the luminescence from binuclear complexes of TbIII (Tb2‐L1 and Tb2‐L2), phosphorylated Tyr residue in peptides was selectively detected in neutral aqueous solutions. Neither the non‐phosphorylated Tyr, pSer, pThr, nor the other phosphate‐containing biomolecules tested affected the luminescence intensity to any notable extent. Upon the binding of the pTyr to these TbIII complexes, the luminescence from the metal ion was notably promoted, as the light energy absorbed by the benzene ring of pTyr is efficiently transferred to the TbIII center. The binding activity of the binuclear TbIII complexes towards pTyr is two orders of magnitude larger than that of the corresponding mononuclear complex. These binuclear complexes were successfully used for real‐time monitoring of enzymatic phosphorylation of a peptide by a tyrosine kinase.
Efficient Photoinduced Energy Transfer Mediated by Aromatic Homoconjugated Bridges
Authors: Osío Barcina José , Herrero‐García Noelia , Cucinotta Fabio , De Cola Luisa , Contreras‐Carballada Pablo , Williams Rene M. , Guerrero‐Martínez Andrés 
Published: April 2010

AbstractA new donor–bridge–acceptor (D‐B‐A) dyad consisting of ruthenium(II) and iridium(III) species separated by an homoconjugated bridge derived from 7,7‐diphenylnorbornane [Ir‐Nor‐Ru]3+ has been synthesised. The photophysical and electrochemical properties of the heterodinuclear complex have been compared with those of the analogous homodinuclear complexes [Ru‐Nor‐Ru]4+ and [Ir‐Nor‐ Ir]2+ . Transient absorption spectra on the nanosecond and sub‐picosecond timescales show, for the first time, that an homoconjugated bridge can mediate efficiently in the photoinduced energy transfer from the iridium(III) to the ruthenium(II) centres according to a Dexter‐type mechanism.
Racemization of the gastrointestinal antisecretory chiral drug esomeprazole magnesium via the pyramidal inversion mechanism: A theoretical study
Authors: Marom Hili , Agranat Israel 
Published: April 2010

AbstractThe pyramidal inversion mechanisms of the 6‐methoxy and the 5‐methoxy tautomers of (S)‐omeprazole were studied, employing ab initio and DFT methods. The conformational space of the model molecule (S)‐2‐[(3‐methyl‐2‐pyridinyl)methyl]sulfinyl‐1H‐benzimidazole was calculated, with respect to rotations around single bonds, at the B3LYP/6‐311G(d,p) level. All of the resulting conformations were used as starting points for full optimizations of (S)‐omeprazole, at B3LYP/6‐31G(d), B3LYP/6‐311G(d,p), B3LYP/6‐311++G(d,p), B3LYP/6‐311G(2df,2pd), MP2/6‐31G(d), and MP2/6‐311G(d,p) levels. Four distinct pathways were found for enantiomerization via the pyramidal inversion mechanism for each of the tautomers of (S)‐omeprazole. Each transition state, in which the sulfur, the oxygen and the two carbon atoms connected directly to the sulfur are in one plane, connects two diastereomeric minima. The enantiomerization is completed by free rotation around the sulfur–methylene bond, and around the methylene–pyridine ring bond. The effective Gibbs' free energy barrier for racemization ΔG of the two tautomers of (S)‐omeprazole are 39.8 kcal/mol (5‐methoxy tautomer) and 40.0 kcal/mol (6‐methoxy tautomer), indicating that the enantiomers of omeprazole are stable at room temperature (in the gas phase). The 5‐methoxy tautomer of (S)‐omeprazole was found to be slightly more stable than the 6‐methoxy tautomer, in the gas phase. The energy barrier (ΔG‡) for the(S,M)
$ \rightleftharpoons $(S,P) diastereomerization of (S)‐omeprazole due to the rotation around the pyridine chiral axis was very low, 5.8 kcal/mole at B3LYP/6‐311G(d,p). Chirality 2010. © 2010 Wiley‐Liss, Inc.
Online coupling of enantioselective capillary gas chromatography with proton nuclear magnetic resonance spectroscopy
Authors: Kühnle Maximilian , Kreidler Diana , Holtin Karsten , Czesla Harri , Schuler Paul , Schurig Volker , Albert Klaus 
Published: April 2010

AbstractThe hyphenation of enantioselective capillary gas chromatography and mass spectrometry is not always sufficient to distinguish between structural isomers, thus requiring peak identification by NMR spectroscopy. Here the first online coupling of enantioselective capillary gas chromatography with proton nuclear resonance spectroscopy is described for the unfunctionalized chiral alkane 2,4‐dimethylhexane resolved on octakis(6‐O‐methyl‐2,3‐di‐O‐pentyl)‐γ‐cyclodextrin at 60°C. NMR allows constitutional and configurational isomers (diastereomers and enantiomers) to be distinguished. Enantiomers display identical spectra at different retention times, which enable an indirect identification of these unfunctionalized alkanes. The presented method is still at an early development stage, and will require instrumental optimization in the future. Chirality 2010. © 2010 Wiley‐Liss, Inc.
Recent advances in asymmetric oxidative coupling of 2‐naphthol and its derivatives
Authors: Wang Hui 
Published: April 2010

AbstractThe enantiomeric atropoisomers of 1,1′‐binaphthyl‐2,2′‐diol (BINOL) have become one of the most widely used chiral ligands and auxiliaries for asymmetric synthesis. This review provides an overview of enantioselective synthesis of optical active BINOLs by straightforward asymmetric oxidative coupling of identical 2‐naphthol and its substituted derivatives. Chirality 2010. © 2010 Wiley‐Liss, Inc.
A novel chiral aliphatic–aromatic diamine promoted direct, highly enantio‐ and diastereoselective Michael addition of cyclohexanone to nitroolefins under solvent‐free conditions
Authors: Miao Shifeng , Bai Jinjin , Yang Jin , Zhang Yawen 
Published: April 2010

AbstractA series of new highly efficient chiral aliphatic–aromatic diamine catalysts have been designed and successfully applied to the asymmetric Michael addition of cyclohexanone with nitroolefins under solvent‐free conditions without any acidic additives. The desired adducts were obtained in high yields with excellent enantio‐ and diastereoselectivities of syn products (up to >99% ee, >99:1 dr). Chirality 2010. © 2010 Wiley‐Liss, Inc
“Can You See Atoms?” – A Reflection from Different Scientific Perspectives
Authors: Parchmann Ilka , Lienau Christoph , Klüner Thorsten , Drögemüller Sarah , Al‐Shamery Katharina 
Published: April 2010

AbstractDieser Beitrag erörtert die Frage, ob man „Atome sehen“ kann, unter chemisch‐physikalischer, aber auch unter erkenntnistheoretischer und fachdidaktischer Perspektive. Dabei wird auf verschiedenen Niveaustufen dargestellt, mit welchen Modellen man Techniken wie die Rastertunnelmikroskopie erklären kann, wo aber auch Grenzen der Darstellung und des Verstehens liegen können. Eine abschließende Reflexion erörtert die Verwendung von Modellen im Chemieunterricht und in der Lehrerbildung.
Alternative Concepts About Density
Authors: Grüß‐Niehaus Thomas , Schanze Sascha 
Published: April 2010

AbstractDichte ist eine Stoffeigenschaft und wird im Chemieanfangsunterricht zur Charakterisierung der Stoffe herangezogen. Oft liegt bereits aus dem Physikunterricht ein Verständnis über die Dichte homogener Körper als Quotient aus Masse und Volumen vor. Mit der Einführung eines Teilchenmodells besteht bei einer unreflektierten Verwendung der lebensweltlichen Vorstellung des „dicht‐aneinander‐gedrängt‐seins“ die Gefahr alternativer Konzepte, sodass zum Beispiel die Unlöslichkeit oder Nicht‐Mischbarkeit über die Dichte zu erklären versucht wird. Dieser Beitrag zeigt konkrete Beispiele dieser Problematik auf und plädiert für eine regelmäßige Thematisierung der Problematik im Unterricht.