bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Expeditious Multigram‐Scale Synthesis of Lysine Dendrigraft (DGL) Polymers by Aqueous N‐Carboxyanhydride Polycondensation
Authors: Collet Hélène , Souaid Eddy , Cottet Hervé , Deratani André , Boiteau Laurent , Dessalces Guy , Rossi Jean‐Christophe , Commeyras Auguste , Pascal Robert 
Published: December 2009

AbstractThe synthesis and characterisation of new arborescent architectures of poly(L‐lysine), called lysine dendrigraft (DGL) polymers, are described. DGL polymers were prepared through a multiple‐generation scheme (up to generation 5) in a weakly acidic aqueous medium by polycondensing Nε‐trifluoroacetyl‐L‐lysine‐N‐carboxyanhydride (Lys(Tfa)‐NCA) onto the previous generation G(n−1) of DGL, which was used as a macroinitiator. The first generation employed spontaneous NCA polycondensation in water without a macroinitiator; this afforded low‐molecular‐weight, linear poly(L‐lysine) G1 with a polymerisation degree of 8 and a polydispersity index of 1.2. The spontaneous precipitation of the growing Nε‐Tfa‐protected polymer (GnP) ensures moderate control of the molecular weight (with unimodal distribution) and easy work‐up. The subsequent alkaline removal of Tfa protecting groups afforded generation Gn of DGL as a free form (with 35–60 % overall yield from NCA precursor, depending on the DGL generation) that was either used directly in the synthesis of the next generation (G(n+1)) or collected for other uses. Unprotected forms of DGL G1–G5 were characterised by size‐exclusion chromatography, capillary electrophoresis and 1H NMR spectroscopy. The latter technique allowed us to assess the branching density of DGL, the degree of which (ca. 25 %) turned out to be intermediate between previously described dendritic graft poly(L‐lysines) and lysine dendrimers. An optimised monomer (NCA) versus macroinitiator (DGL G(n−1)) ratio allowed us to obtain unimodal molecular weight distributions with polydispersity indexes ranging from 1.3 to 1.5. Together with the possibility of reaching high molecular weights (with a polymerisation degree of ca. 1000 for G5) within a few synthetic steps, this synthetic route to DGL provides an easy, cost‐efficient, multigram‐scale access to dendritic polylysines with various potential applications in biology and in other domains.
Chirality in Dynamic Supramolecular Nanotubes Induced by a Chiral Solvent
Authors: Isare Benjamin , Linares Mathieu , Zargarian Loussiné , Fermandjian Serge , Miura Motofumi , Motohashi Shigeyasu , Vanthuyne Nicolas , Lazzaroni Roberto , Bouteiller Laurent 
Published: December 2009

AbstractAmplification of chirality has been reported in polymeric systems. It has also been shown that related effects can occur in polymer‐like dynamic supramolecular aggregates, if a subtle balance between noncovalent interactions allows the coupling between a chiral information and a cooperative aggregation process. In this context, we report a strong majority‐rules effect in the formation of chiral dynamic nanotubes from chiral bisurea monomers. Furthermore, similar helical nanotubes (with the same circular dichroism signature) can be obtained from racemic monomers in a chiral solvent. Competition experiments reveal the relative strength of the helical bias induced by the chiral monomer or by the chiral solvent. The nanotube handedness is imposed by the monomer chirality, whatever the solvent chirality. However, the chirality of the solvent has a significant effect on the degree of chiral induction.
Physicochemical Characterization of Transport in Nanosized Membrane Structures
Authors: Darvishmanesh Siavash , Degrève Jan , Van der Bruggen Bart 
Published: December 2009

AbstractThe understanding of polymer–solvent interactions is highly important for the development of tailored membrane manufacturing procedures and for the prediction of membrane performance from transport mechanisms. This study examines the permeation performance of organic solvents through state‐of‐the‐art polyimide membranes (STARMEM, Membrane Extraction Technology Ltd.). Solvents are systematically selected to allow investigation of the effects of key physicochemical transport parameters by keeping constant all other parameters thought to be relevant. The effect of the solubility parameter, polarity (dielectric constant), surface tension, and viscosity are studied in detail. Dead‐end permeation experiments are carried out at 20 bar with STARMEM 122 and STARMEM 240 membranes. Results for the selected solvents show higher permeation rates for ketones over alcohols and aromatics as well as for acids. It is suggested that the viscosity and polarity have a greater influence than the other parameters. The effect of solvent molar volume is also investigated. Transport of solvents with high molar volume, independent of their polarity and compatibility with the membrane material, is slower in all cases than for solvents with smaller molar volume. The solubility parameter does not show any significant effect on transport phenomena.
Very Low Energy Electrons Transform the Cyclobutane‐Pyrimidine Dimer into a Highly Reactive Intermediate
Authors: Edtbauer Achim , Denifl Stephan , Vizcaino Violaine , An der Lan Lukas , Russell Katherine , Taubitz Jörg , Wille Uta , Feketeova Linda , O'Hair Richard A. J. , Märk Tilmann D. , Illenberger Eugen , Scheier Paul 
Published: December 2009

AbstractElectrons with virtually no kinetic energy (close to 0 eV) trigger the decomposition of cytotoxic cyclobutane‐pyrimidine dimer (CPD) into a surprisingly large variety of fragment ions plus their neutral counterparts. The response of CPD to low energy electrons is thus comparable to that of explosives like trinitrotoluene (TNT). The dominant unimolecular reaction is the splitting into two thymine like units, which can be considered as the essential molecular step in the photolyase of CPD. We find that CPD is significantly more sensitive towards low energy electrons than its thymine building blocks. It is proposed that electron attachment at very low energy proceeds via dipole bound states, supported by the large dipole moment of the molecule (6.2 D). These states act as effective doorways to dissociative electron attachment (DEA).
Development of a flow cytometric co‐immunoprecipitation technique for the study of multiple protein—protein interactions and its application to T‐cell receptor analysis
Authors: Bridgeman John S. , Blaylock Morgan , Hawkins Robert E. , Gilham David E. 
Published: December 2009

AbstractCo‐immunoprecipitation is the classical approach for investigating protein–protein interactions. Analysis is generally conducted using the Western blot approach. We set out to investigate whether flow cytometry was a feasible alternative to Western blotting. Using the TCR‐CD3 complex as a model for intermolecular interactions in the MA5.8 cell line, FLAG‐tagged CD3ζ‐scFv fusion proteins could be captured on anti‐FLAG coupled beads and associated TCRβ molecules could be detected by flow cytometry. This association was abrogated by mutations to the CD3ζ transmembrane domain. Using multicolor flow cytometry, TCRβ, CD3ε, and the scFv region of the CD3ζ fusion molecule could all be detected from a single sample. This multicolor analysis was then applied to demonstrate the importance of correct lysis conditions for extraction of the TCR complex. In summary, this flow cytometric immunoprecipitation technique is a feasible alternative to classical co‐immunoprecipitation analysis technique and offers many potential advantages including rapid analysis with increased target sensitivity, reduced technical demands, amenable to multiple protein analysis from a single sample, and provides a framework that may facilitate the development of high throughput analytical assays investigating protein–protein interactions. © 2009 International Society for Advancement of Cytometry
Characterization of the neuroligin gene family expression and evolution in zebrafish
Authors: Rissone Alberto , Sangiorgio Lorenzo , Monopoli Matteo , Beltrame Monica , Zucchi Ileana , Bussolino Federico , Arese Marco , Cotelli Franco 
Published: December 2009

AbstractNeuroligins constitute a family of transmembrane proteins localized at the postsynaptic side of both excitatory and inhibitory synapses of the central nervous system. They are involved in synaptic function and maturation and recent studies have linked mutations in specific human Neuroligins to mental retardation and autism. We isolated the human Neuroligin homologs in Danio rerio. Next, we studied their gene structures and we reconstructed the evolution of the Neuroligin genes across vertebrate phyla. Using reverse‐transcriptase polymerase chain reaction, we analyzed the expression and alternative splicing pattern of each gene during zebrafish embryonic development and in different adult organs. By in situ hybridization, we analyzed the temporal and spatial expression pattern during embryonic development and larval stages and we found that zebrafish Neuroligins are expressed throughout the nervous system. Globally, our results indicate that, during evolution, specific subfunctionalization events occurred within paralogous members of this gene family in zebrafish. Developmental Dynamics 239:688–702, 2010. © 2009 Wiley‐Liss, Inc.
Sperm and oocyte communication mechanisms controllingC. elegansfertility
Authors: Han Sung Min , Cottee Pauline A. , Miller Michael A. 
Published: December 2009

AbstractDuring sexual reproduction in many species, sperm and oocyte secrete diffusible signaling molecules to help orchestrate the biological symphony of fertilization. In theCaenorhabditis elegansgonad, bidirectional signaling between sperm and oocyte is important for guiding sperm to the fertilization site and inducing oocyte maturation. The molecular mechanisms that regulate sperm guidance and oocyte maturation are being delineated. Unexpectedly, these mechanisms are providing insight into human diseases, such as amyotrophic lateral sclerosis, spinal muscular atrophy, and cancer. Here we review sperm and oocyte communication inC. elegansand discuss relationships to human disorders. Developmental Dynamics 239:1265–1281, 2010. © 2009 Wiley‐Liss, Inc.
A hybrid multirate MAC protocol providing trade‐off between throughput and fairness in future TD‐CDMA networks
Authors: Vlacheas Panagiotis T. , Kolokotroni Eleni A. , Tragos Elias Z. , Theologou Michael E. 
Published: December 2009

AbstractIn this paper, a hybrid, frequency division duplex (FDD), time division–code division multiple access (TD‐CDMA), medium access control (MAC) protocol is proposed. Both multicode (MC) and orthogonal variable spreading factor (OVSF) transmission modes are used in order to utilise the system resources more efficiently. Moreover, a new rate‐scheduling algorithm is developed, aimed at providing a trade‐off between throughput maximisation and fairness, while satisfying QoS requirements. The above scheme is formulated as a constrained optimisation problem, which maximises the sum of normalised rates instead of throughput in order to achieve fairer rate allocations, while maintaining throughput at a high value. A new optimisation constraint is introduced in order to deal with the discrete set of available rates that the hybrid MC‐OVSF scheme supports. Copyright © 2009 John Wiley & Sons, Ltd.
Brief problem‐solving treatment in primary care (pst‐pc) was not more effective than placebo for elderly patients screened positive of psychological problems
Authors: Lam Cindy L. K. , Fong Daniel Y. T. , Chin Weng‐Yee , Lee Peter W. H. , Lam Elegance T. P. , Lo Yvonne Y. C. 
Published: December 2009

AbstractObjectivesTo evaluate whether screening followed by brief problem‐solving treatment by primary care doctors (PST‐PC) could improve health‐related quality of life (HRQOL) and reduce consultation rates in the elderly.DesignA single‐blind randomized placebo controlled trial (RCT).SettingTwo government funded primary care clinics in Hong Kong.ParticipantsTwo hundred and ninety nine Chinese patients aged 60 years or over, with positive screening scores for psychological problems by the Hospital Anxiety and Depression Scale (HADS).InterventionsOne hundred and forty nine subjects were randomized to receive brief PST‐PC from primary care doctors (treatment) and 150 to group video‐viewing (placebo). All subjects were followed up by telephone at 6, 12, 26 and 52 weeks.Main Outcome MeasuresChanges in SF‐36 HRQOL scores, HADS scores and monthly consultation rates were compared within and between groups.ResultsStudy completion rates were 69–71%. There was significant improvement in the SF‐36 role‐emotional (RE) and mental component summary (MCS) scores at week 6 in the PST‐PC group but not in the placebo group. Several SF‐36 scores improved significantly in the placebo (video) group at week 6–52. Mixed effects analysis adjusting for baseline values and cofounders did not show any difference in any of the outcomes between the PST‐PC and placebo (video) groups.ConclusionsScreening followed by brief PST‐PC was associated with a short‐term improvement in HRQOL in Chinese elderly patients screened positive of psychological problems, but the HRQOL benefit was not greater than those found in the placebo group who participated in group‐viewings of health education videos. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of N‐methylmorpholine N‐(17O‐oxide) and N‐methylmorpholine 15N‐(17O‐oxide)
Authors: Opietnik Martina , Potthast Antje , Kitaoka Takuya , Rosenau Thomas 
Published: December 2009

AbstractN‐Methylmorpholine N‐(17O‐oxide) and N‐methylmorpholine 15N‐(17O‐oxide) were prepared from N‐methylmorpholine and 15N‐methylmorpholine by oxidation with H2 17O2. The facile one‐pot procedure provided yields of 82 and 76%, respectively. The labeled hydrogen peroxide was obtained by electrolysis of H2 17O followed by autoxidation of 2‐ethylanthraquinol with the molecular oxygen 17O2 generated. The compounds serve for mechanistic studies into gold nanoparticle generation in NMMO solution. Copyright © 2009 John Wiley & Sons, Ltd.
The utilization of rice bran wax to stabilize long chain ω‐3 polyunsaturated fatty acid esters
Authors: Kodali Dharma R. 
Published: December 2009

AbstractOils containing long chain ω‐3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are highly susceptible to oxidation, limiting their use in food products and drinks. To stabilize these oils, they are usually fortified with natural and/or synthetic antioxidants. Here we report for the first time the use of a novel natural and edible ingredient, rice bran wax (RBX), that improves the oxidative stability of polyunsaturated ω‐3 oils. When the wax esters are dissolved in polyunsaturated oils at low concentrations (⪈0.5%) and cooled, the wax molecules solidify into a thin crystalline mesh and entrap large volumes of liquid oil. Such encapsulated solids with large volumes of liquid oil are called organogels. Encapsulated menhaden oil with 1.5% RBX containing no added anti‐oxidant, showed oxidative stability comparable to menhaden oil with 500 ppm of tocopherols and 200ppm tert‐butylhydroquinone (TBHQ). Incorporation of RBX to stabilize ω‐3 oils is advantageous as it provides a “natural” label at a modest cost.
Cellular Evaluation of Synthesized Insulin/Transferrin Bioconjugates for Oral Insulin Delivery Using Intelligent Complexation Hydrogels
Authors: Shofner Justin P. , Phillips Margaret A. , Peppas Nicholas A. 
Published: December 2009

AbstractInsulin transport across the epithelial cell layer in the small intestine was studied using insulin/transferrin conjugates with and without the presence of P(MAA‐g‐EG) microparticles in contact with a co‐culture of Caco‐2/HT29‐MTX cells. The insulin/transferrin conjugate was shown to increase transport relative to pure insulin by a factor of 7, achieving an apparent permeability of 37 × 109 cm · s−1. The presence of P(MAA‐g‐EG) microparticles increased conjugate transport by a factor of 14 times relative to insulin, achieving an apparent permeability of 72.8 × 109 cm · s−1. The presence of the microparticles in solution was found to improve conjugate transport by nearly 100% with little to no change in cell monolayer integrity.magnified image
Photochemical Reactions of Poly(4‐vinylphenol) Thin Films
Authors: Uppalapati Suji , Chada Sailaja , Engelhard Mark H. , Yan Mingdi 
Published: December 2009

AbstractThe mechanism involved in the photochemical immobilization of poly(4‐vinylphenol) (PVP) thin films was investigated. The films were fabricated by a simple procedure of UV irradiation and solvent extraction. A combination of ellipsometry, IR, and high‐resolution X‐ray photoelectron spectroscopy (XPS) was used to provide detailed and quantitative analysis of the composition of the photochemical reaction products. Upon irradiation at 260 nm, benzyl and phenoxy radicals are generated in the polymer. In the absence of oxygen, PVP films crosslinked via the combination of the benzyl radicals or phenoxy radicals. At lower irradiation doses, the photochemical process was dominated by crosslinking of the polymer backbone via the combination of benzyl radicals. At higher exposure doses, crosslinked quinoid structures were generated, and the concentration increased with the irradiation time. No oxidation or degradation products were observed. In the presence of oxygen, additional reactions of oxidation and degradation occurred. At lower doses, oxidation at the benzyl position produced the ketone structure evidenced by the drastic increase in the O content in the irradiated films. As the irradiation doses increased, further oxidation at the methylene position occurred, and in addition, volatile and degradation products were also generated. This photochemical process was successfully employed to fabricate patterned PVP structures.magnified image
ATRP of Styrene and Methyl Methacrylate with Less Efficient Catalysts and with Alkyl Pseudohalides as Initiators/Chain Transfer Agents
Authors: Kwak Yungwan , Yamamura Yuichi , Matyjaszewski Krzysztof 
Published: December 2009

AbstractLigands, such as Me4cyclam and anionically charged BPAA, providing low values of kda and less efficient for ATRP with alkyl halides, were successfully used for ATRP in the presence of alkyl pseudohalides as initiators/chain transfer agents, resulting in well‐controlled PSt and PMMA. Although the catalysts with these ligands provide a poor control for ATRP with alkyl halides as initiators, the pseudohalides such as dithioesters yield well‐controlled concurrent ATRP/RAFT. The propagating radicals were generated directly from the CTA in the absence of conventional radical initiators, such as AIBN, that are required for a conventional RAFT polymerization. This system is an example of the synergetic cooperation between ATRP and RAFT polymerization procedures that suppresses new chain generation by direct activation of CTA with a copper complex to supply radicals and utilizes fast chain transfer reactions to provide control of the polymerization.magnified image
Maximal operators on variable Lebesgue spaces with weights related to oscillations of Carleson curves
Authors: Karlovich Alexei Yu. 
Published: December 2009

AbstractWe prove sufficient conditions for the boundedness of the maximal operator on variable Lebesgue spaces with weights φt,γ (τ) = |(τ – t)γ |, where γ is a complex number, over arbitrary Carleson curves. If the curve has different spirality indices at the point t and γ is not real, then φt,γ is an oscillating weight lying beyond the class of radial oscillating weights considered recently by V. Kokilashvili, N. Samko, and S. Samko (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sheaves of C*‐algebras
Authors: Ara Pere , Mathieu Martin 
Published: December 2009

AbstractWe develop the basics of a theory of sheaves of C*‐algebras and, in particular, compare it to the existing theory of C*‐bundles. The details of two fundamental examples, the local multiplier sheaf and the injective envelope sheaf, are discussed (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toeplitz matrices with variable coefficients, pseudodifferential operators, and Strichartz's method
Authors: Shargorodsky Eugene 
Published: December 2009

AbstractWe present simple proofs of sharp uniform boundedness results for sequences of Toeplitz matrices with variable coefficients. These proofs are based on Strichartz's method which reduces the problem of boundedness of operators “with variable coefficients” to the same problem for operators that have “constant coefficients” but act on Hilbert space valued functions. The paper also contains counterexamples showing the optimality of the boundedness results obtained with the help of Strichartz's method and a brief discussion of similar results for pseudodifferential operators (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erhard Schmidt and his contributions to functional analysis
Authors: Pietsch Albrecht 
Published: December 2009

AbstractErhard Schmidt is considered to be one of the leading German mathematicians in the first half of the twentieth century. This article is a tribute to him that was written on the occasion of the 50thanniversary of his death (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical integration and discrepancy, a new approach
Authors: Triebel Hans 
Published: December 2009

AbstractThe paper deals with two closely related topics: (i) Numerical integration of functions belonging to Sobolev‐Besov spaces with dominating mixed smoothness in cubes. (ii) Discrepancy measured in terms of Lebesgue and Sobolev‐Besov spaces (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymer Single Crystal Templated Janus Nanoparticles
Authors: Wang Bingbing , Li Bing , Ferrier Robert C. M. , Li Christopher Y. 
Published: December 2009

AbstractTop‐selective surface modification has been widely used for the synthesis of Janus nanoparticles (NPs). Herein we demonstrate that polymer single crystals can serve as generic substrates to immobilize NPs and the resultant NPs are Janus in nature. This technique is generic because various NPs as well as polymer single crystal substrates can be used. Single crystals of poly(ethylene oxide), polycaprolactone, and polyethylene‐block‐poly(ethylene oxide) have been successfully used to immobilize gold, magnetic, and semiconducting NPs. Subsequent dissolution of the single crystals led to various types of Janus NPs and NP clusters with different polymer brushes.magnified image
Synthesis and characterization of phenolic‐type beads by dispersion polymerization of 2‐phenoxyethanol with formaldehyde using gum acacia powder as stabilizer
Authors: Liu Li , Ji Chunnuan , Song Shuhui , Sun Changmei , Qu Rongjun , Wang Chunhua , Chen Hou 
Published: December 2009

AbstractIn this study, we report the preparation of phenolic beads (PB) via a novel dispersion polymerization of 2‐phenoxyethanol (PE) and formaldehyde, in which gum acacia powder (GAP), formic acid, and sulfuric acid are employed as the steric stabilizer, the reaction medium and the catalyst, respectively. The effects of a variety of reaction parameters, including the stabilizer concentration, the agitation rate, the polymerization temperature, the molar ratio of formaldehyde to 2‐phenoxyethanol (F/P) and the amount of sulfuric acid, on the particle size and size distribution (PDI) as well as particle morphology have been investigated. Particularly, phenolic beads of a size 565 µm as well as a narrow particle size distribution (PDI = 1.153) have been prepared under the following conditions: the stabilizer concentration 2.5%, the agitation rate 700 rpm, the polymerization temperature 60°C, the molar F/P ratio 3:1, and the amount of catalyst 8 ml. In addition, a mechanism for the particle formation in dispersion polymerization of PE and formaldehyde has also been proposed. Copyright © 2009 John Wiley & Sons, Ltd.