bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wordom: A user‐friendly program for the analysis of molecular structures, trajectories, and free energy surfaces
Authors: Seeber Michele , Felline Angelo , Raimondi Francesco , Muff Stefanie , Friedman Ran , Rao Francesco , Caflisch Amedeo , Fanelli Francesca 
Published: November 2010

AbstractWordom is a versatile, user‐friendly, and efficient program for manipulation and analysis of molecular structures and dynamics. The following new analysis modules have been added since the publication of the original Wordom paper in 2007: assignment of secondary structure, calculation of solvent accessible surfaces, elastic network model, motion cross correlations, protein structure network, shortest intra‐molecular and inter‐molecular communication paths, kinetic grouping analysis, and calculation of mincut‐based free energy profiles. In addition, an interface with the Python scripting language has been built and the overall performance and user accessibility enhanced. The source code of Wordom (in the C programming language) as well as documentation for usage and further development are available as an open source package under the GNU General Purpose License from http://wordom.sf.net. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
In silico prediction of deleterious single amino acid polymorphisms from amino acid sequence
Authors: Li Shuyan , Xi Lili , Li Jiazhong , Wang Chengqi , Lei Beilei , Shen Yulin , Liu Huanxiang , Yao Xiaojun , Li Biao 
Published: November 2010

AbstractMolecular cause of human disease retains as one of the most attractive scientific research targets for decades. An effective approach toward this topic is analysis and identification of disease‐related amino acid polymorphisms. In this work, we developed a concise and promising deleterious amino acid polymorphism identification method SeqSubPred based on 44 features solely extracted from protein sequence. SeqSubPred achieved surprisingly good predictive ability with accuracy (0.88) and area under receiver operating characteristic (0.94) without resorting to homology or evolution information, which is frequently used in similar methods and usually more complex and time‐consuming. SeqSubPred also identified several critical sequence features obtained from random forests model, and these features brought some interesting insights into the factors affecting human disease‐related amino acid substitutions. The online version of SeqSubPred method is available at montana.informatics.indiana.edu/cgi‐bin/seqmut/seqsubpred.cgi © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
The charge‐transfer states in a stacked nucleobase dimer complex: A benchmark study
Authors: Aquino Adélia J. A. , Nachtigallova Dana , Hobza Pavel , Truhlar Donald G. , Hättig Christof , Lischka Hans 
Published: November 2010

AbstractElectronic singlet excitations of stacked adenine–thymine (AT) and guanine–cytosine (GC) complexes have been investigated with respect to local excitation and charge‐transfer (CT) characters. Potential energy curves for rigid displacement of the nucleobases have been computed to establish the distance dependence of the CT states. The second‐order algebraic diagrammatic construction [ADC(2)] method served as reference approach for comparison to a selected set of density functionals used within the time‐dependent density functional theory (TD‐DFT). Particular attention was dedicated to the performance of the recently developed family of M06 functionals. The calculations for the stacked complexes show that at the ADC(2) level, the lowest CT state is S6 for the AT and as S4 for the GC pair. At the reference geometry, the actual charge transferred is found to be 0.73 e for AT. In case of GC, this amount is much smaller (0.17 e). With increasing separation of the two nucleobases, the CT state is strongly destabilized. The M06‐2X version provides a relatively good reproduction of the ADC(2) results. It avoids the serious overstabilization and overcrowding of the spectrum found with the B3LYP functional. On the other hand, M06‐HF destabilizes the CT state too strongly. TD‐DFT/M06‐2X calculations in solution (heptane, isoquinoline, and water) using the polarizable continuum model show a stabilization of the CT state and an increase in CT character with increasing polarity of the solvent. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
“Hugging sisters”: Thoracoomphalopagus with anencephaly confirmed by three‐dimensional ultrasonography at 9 weeks of gestation
Authors: Shim Jae‐Yoon , Joo Da‐Hye , Won Hye‐Sung , Lee Pil Ryang , Kim Ahm 
Published: November 2010

AbstractWe describe a rare conjoined twinning at 9 weeks of gestation. We compared the results of two‐ and three‐dimensional sonography with autopsy findings after the termination of pregnancy. These results showed a thoracoomphalopagus with a shared heart and visceral organs. Three‐dimensional sonography showed anencephaly in one of the embryos. Early and accurate prenatal diagnosis of this type of conjoined twins using three‐dimensional sonography is critical for both parental counseling and minimizing maternal morbidity. © 2010 Wiley Periodicals, Inc. J Clin Ultrasound, 2011
Traumatic stress, affect dysregulation, and dysfunctional avoidance: A structural equation model
Authors: Briere John , Hodges Monica , Godbout Natacha 
Published: November 2010

AbstractThe multivariate relationship between interpersonal trauma, posttraumatic stress, affect dysregulation, and various avoidance behaviors was examined in a sample of 418 trauma‐exposed participants from the general population. Structural equation modeling indicated that (a) suicidality, substance abuse, dissociation, and problematic activities such as self‐injury and dysfunctional sexual behaviors were all indicators of a robust latent variable, named dysfunctional avoidance, (b) accumulated exposure to various types of interpersonal trauma was associated with this avoidance factor, and (c) the relationship between trauma and dysfunctional avoidance was independently mediated by both posttraumatic stress and diminished affect regulation capacity.
Nanoparticles by ROMP in Nonaqueous Emulsions
Authors: Haschick Robert , Klapper Markus , Wagener Kenneth B. , Müllen Klaus 
Published: November 2010

AbstractThe use of nonaqueous emulsions to synthesize particles by ROMP is described. The applied emulsions – consisting of two immiscible, organic, aprotic solvents – are versatile reaction systems for the preparation of polymer particles from moisture sensitive monomers and catalysts. Whereas up to now only polycondensations or polyadditions have been utilized in nonaqueous emulsions, catalytic polymerizations are now presented. Four different functionalized norbornene derivatives were applied for ROMP by a second‐generation Grubbs catalyst to form polymer nanoparticles. Furthermore, core/shell and surface functionalized nanoparticles applicable to “click” reactions were prepared to demonstrate the use of different polymerization procedures in one pot.magnified image
Complex Inorganic/Organic Core‐Shell Particles by an Inverse Emulsion Technique
Authors: Schmidtke Kathy , Stelzig Simon H. , Geidel Christian , Klapper Markus , Müllen Klaus 
Published: November 2010

AbstractTwo synthetic approaches to modify the surface of inorganic particles are presented. In the first approach the inorganic particles are prepared in‐situ in a confined space in inverse emulsions. The used amphiphilic statistical copolymers act not only as emulsifiers, but they also hydrophobize the remaining inorganic particles after the precipitation. This approach represents a versatile method to obtain various inorganic nanoparticles as well as more complex inorganic materials like core‐multiple shell and perovskite‐based nanoparticles. The second procedure uses preformed inorganic particles, as an aqueous dispersion, to modify them with surface active amphiphilic copolymers in a multicomponent solvent system. This method turns out to be a simple but highly efficient method to modify preformed inorganic nanoparticles. The particles are characterized by SEM, TEM and dynamic light scattering. The modified inorganic nanoparticles are suitable to be homogenously incorporated into a polymer matrix to form transparent nanocomposite materials.
Alternating Ring‐Opening Metathesis Copolymerization of Norborn‐2‐ene with cis‐Cyclooctene and Cyclopentene
Authors: Vehlow Kati , Lichtenheldt Martin , Wang Dongren , Blechert Siegfried , Buchmeiser Michael R. 
Published: November 2010

AbstractRu‐alkylidenes based on unsymmetrical imidazolin‐2‐ylidenes, were used for the alternating copolymerization of norborn‐2‐ene (NBE) with cis‐cyclooctene (COE) and cyclopentene (CPE), respectively. Alternating copolymers, i.e., poly(NBE‐alt‐COE)n and poly(NBE‐alt‐CPE)n containing up to 97 and 91% alternating diads, respectively, were obtained. The copolymerization parameters of the alternating copolymerization of NBE with CPE under the action of different initiators were determined using a first order Markov model. Hydrogenation of poly(NBE‐alt‐COE)n yielded a fully saturated, hydrocarbon‐based polymer.
Controlled Free‐Radical Copolymerization of N‐vinyl succinimide and n‐Butyl acrylate via a Reversible Addition–Fragmentation Chain Transfer (RAFT) Technique
Authors: Sivtsov Eugene , Chernikova Elena , Gostev Alexey , Garina Elizaveta 
Published: November 2010

AbstractSummary: Copolymerization of N‐vinyl succinimide and n‐butyl acrylate in the presence of dibenzyl trithiocarbonate as a reversible addition‐fragmentation chain transfer agent was investigated. The linear dependence of molecular mass on conversion and low values of polydispersity index confirmed pseudo‐living mechanism of the process. For the first time the soluble copolymers of N‐vinyl succinimide and n‐butyl acrylate with high composition homogeneity have been synthesized by copolymerization in bulk. The copolymerization kinetics was studied by NMR 1H spectroscopy; the reactivity ratios were determined: rVSI = 0.11, rBA = 2.54. The copolymer microstructure was estimated; it was shown that in conditions of RAFT polymerization gradient copolymers enriched with BA on the tails of the macromolecule and with VSI in the middle can be obtained. The method of elimination of trithiocarbonate fragment by the reaction with an excess of AIBN was proposed leading to formation of the simplest gradient structure of N‐vinyl succinimide – n‐butyl acrylate copolymer.
Nanoimprint Lithography with UV‐Curable Hyperbranched Polymer Nanocomposites
Authors: Geiser Valérie , Jin Young‐Hyun , Leterrier Yves , Månson Jan‐Anders E. 
Published: November 2010

AbstractNano‐scale patterns were produced with UV‐curable acrylated hyperbranched polymer nanocomposites using nanoimprint lithography with a glass master in a rapid, low‐pressure process. The pattern of the glass master was replicated with composites containing up to 25 vol% SiO2 with a shape fidelity better than 98%. Photo‐rheology, interferometry and atomic force microscopy were used to analyze the material behavior. Attention was paid to the relationship between composition, nanoparticle dispersion, kinetics of photo‐polymerisation, shrinkage, pressure and shape fidelity of nano‐gratings. It was shown that the gel‐point of the nanocomposite was an important factor that determined the stability as well as the dimensions of the imprinted structure. Dimensional accuracy also strongly depended on the level of internal stress, which in fact increased with the amount of silica. A resin rich layer on the surface of the composite accounted for the good surface quality of the nano‐pattern.
Comparison of Different Analytical Methods for Volatile and Odour‐Active Substances in Polyolefins
Authors: Hopfer Helene , Sauer Christian , Haar Nina , Leitner Erich 
Published: November 2010

AbstractEmissions of volatiles of polymeric materials are an important parameter for materials characterisation, and gain more and more importance either by their odour activity or by other undesired behaviour. Currently, numerous methods are applied for the determination of volatiles, but all of them use gas chromatography (GC) with different detectors. The information gained by flame ionisation detection (FID) is the total emitted volatiles expressed as a sum value, but no further deeper information is provided. Additionally, due to different sample amounts, preparation, way of sampling and GC parameters, results cannot be compared to each other. Also, determination of single sum values by integrating the total area of volatiles is of little help for material development due to the lack of detailed information about chemical composition, and other methods have to be applied. Other compounds of interest such as odour‐active ones turn up in only very small amounts and cannot be detected by these methods as an extensive analytical sample preparation is necessary. We compare results obtained by different sample preparation techniques used in industrial standards (VDA 277 and VDA278) to scientific alternatives such as Solid Phase Microextraction (SPME) coupled to GC with mass spectrometry (MS) and Simultaneous Distillation/Extraction SDE coupled to GC‐MS to demonstrate capabilities and applicability of each method.
Neutron Scattering Studies of Structure and Self‐Assembly of Star‐Shaped Polymers with Fullerene Centres in Solutions
Authors: Lebedev Vasily , Vinogradova Lyudmila , Török Gyula 
Published: November 2010

AbstractProtonated star‐shaped polystyrenes with single and double fullerene C60 core and the hybrid stars with pairs of polar and non‐polar arms (tertbuthylmetacrylate, polystyrene) have been studied in deuterated toluene (20 °C) by small‐angle neutron scattering at low and moderate polymer concentrations (c1 ∼ 1 g/dl, c2 ∼ 3–6 g/dl) to evaluate the peculiarities of fullerene centre action on polymers self‐assembly in solutions. As we found, the cores composed of two fullerenes, linked via Si(CH3)2‐bridge, induce stars' anisotropic interactions and association into chain‐like structures (correlation radius ∼400–600 nm). Meanwhile, the single‐core stars of polystyrene and hybrids organize globular clusters (size ∼ 103 nm) those geometry do not change significantly by polymer content variation.
Development of Injectable Biodegradable Multi‐Arms PEG‐Based Hydrogels: Swelling and Degradation Investigations
Authors: Wang David , Hill David J.T. , Peng Hui , Symons Anne , Varanasi Srinivas , Whittaker Andrew K. , Rasoul Firas 
Published: November 2010

AbstractSummary: Injectable biodegradable hydrogels have been developed to determine the efficacy of biomaterials for the treatment of periodontitis through control delivery of bone‐healing bioactives. The hydrogels were prepared from the PEG‐ylated macromer of Boltorn™ H20 (BH20) and an acrylated triblock copolymer of polylactide‐polyethylene glycol (2k)‐polylactide (PLA) in various molar ratios using ammonium persulfate and sodium ascorbate as a free radical initiating system. Preliminary investigations involving the synthesis of PLA hydrogels with different PLLA block lengths were studied in order to determine the swelling ratios and degradation rates of the biodegradable component of the hydrogels prior to copolymerization with BH20. The swelling and degradation studies of PLA with PEG diacrylate (FW 700) hydrogels were established in phosphate buffered saline (PBS) at 37 °C, pH 7.4 and in water (pH ∼5.5). They have been shown to have low swelling ratios (Qmax = 4.4 to 3.6) and degradation times of 20–30 days. The swelling and degradation parameters were found to be dependent on the molar ratio of the PEG diacrylate to PLA in the copolymer.
Control of McKibben Polymeric Artificial Muscles by Means of Buffer Solutions
Authors: Tondu B. , Mathé S. , Emirkhanian R. 
Published: November 2010

AbstractReversible swelling and de‐swelling of pH reactive polymers are mainly made using strong bases and strong acids, typically with pH equal to 0 or 1 and 14 or 13. As a consequence, pH‐artificial muscles are triggered off at a pH too high for internal use of such muscles inside the human body. The paper analyses the possibility of using weak base‐weak acid buffers to generate the ion circulation necessary for swelling/de‐swelling phenomena with a limited pH‐range. The paper further reports experiments with ion‐exchange resins swelling and de‐swelling in response to standard NaHCO3/CH3COOH + CH3COONa weak base‐weak acid solutions. The ion exchange resin is placed inside the inner tube of a McKibben‐braided structure whose functioning we have discussed elsewhere in connection with its reliability to define a chemo‐mechanical artificial muscle with static and dynamic behaviour close to human skeletal muscle. We experimentally show that a 0.25 M buffer solution leads to a maximum isometric force and a contraction time response similar to that obtained with 0.1 M NaOH/HCl strong base‐strong acid. As a consequence, our McKibben polymeric artificial muscle is now controlled within a 3.8 pH‐range: muscle contraction is triggered at about 8.3 pH, and muscle relaxation at about a 4.5 pH. The dynamic performance of a 170 mm long/7 mm diameter in isotonic mode, with loads between 0.25 kg to 10 kg, is reported.
Dynamics of the Alignment of Mammalian Cells on a Nano‐Structured Polymer Surface
Authors: Peterbauer Thomas , Yakunin Sergii , Siegel Jakub , Heitz Johannes 
Published: November 2010

AbstractIn vitro cultured mammalian cells are able to sense micro‐ and nanotopographical features of their substratum, resulting in contact guidance of the cells along topographical features, altered motility, proliferation and differentiation. We here used embossed polyester films with nanogrooves to study the dynamics of cell spreading and alignment of chinese hamster ovary (CHO) cells and cells of a rat myogenic cell line. Our results suggest that the response of the cells studied is driven by initial cytoplasmic protrusions, which emerge along the nanogrooves and pull the cells along the direction of the nanogrooves.
Towards Targeted Drug Delivery by Covalent Ligand‐Modified Polymeric Nanocontainers
Authors: Egli Stefan , Fischer Barbara , Hartmann Sonja , Hunziker Patrick , Meier Wolfgang , Rigler Per 
Published: November 2010

AbstractHere we present a novel strategy for specific cellular targeting of polymeric nanocontainers by using self‐assembly of block copolymers consisting of either Polydimethoxysiloxane‐b‐Polymethyloxazoline‐b‐Polydimethoxysiloxane (PDMS‐b‐PMOXA‐b‐PDMS) or functionalized PDMS‐b‐PMOXA‐b‐PDMS. Covalent functionalization of the above copolymer was accomplished using either the fluorescent dye sulforhodamine B or a poly‐guanosin ligand, the latter by using the Huisgen 1,3‐dipolar cycloaddition. The success of the covalent modification of the block copolymer has been determined by studying functionalized sulforhodamine B by NMR and fluorescence correlation spectroscopy. The covalent click chemistry approach leads to efficiently functionalized polymeric nanocontainers which enables specific uptake by activated macrophages overexpressing the scavenger receptor A1.
Hydrolysis of Cutin by PET‐Hydrolases
Authors: Korpecka Justyna , Heumann Sonja , Billig Susan , Zimmermann Wolfgang , Zinn Manfred , Ihssen Julian , Cavaco‐Paulo Artur , Guebitz Georg M. 
Published: November 2010

AbstractFunctionalisation of synthetic polymers by using enzymes has been recently demonstrated. The major advantage of enzymes over chemical processes lies in their surface specific and endo‐wise mode of action. Surface hydrophilisation of PET with lipases and cutinases leads to a dramatic increase of the surfacial acid and hydroxyl group content while conventional chemical treatment does not cause any change. However, this PET‐hydrolysing activity by enzymes from distinct classes has not yet been correlated to activity on natural polyesters. Here, we show that lipases, cutinases and a PHA‐depolymerase are all capable of hydrolysing PET, while only lipases and cutinases also hydrolysed cutin to various degrees. Lipases showed a higher specificity for terminal fatty acids while the cutinases preferred hydroxy fatty acids during cutin hydrolysis.
Tracking the Structure‐Reactivity Relationship of Zinc Guanidine‐Pyridine Hybrid Complexes Initiating Lactide Polymerisation
Authors: Börner Janna , Flörke Ulrich , Döring Artjom , Kuckling Dirk , Herres‐Pawlis Sonja 
Published: November 2010

AbstractSummary: Three zinc guanidine‐pyridine hybrid complexes [Zn(TMGqu)2(CH3SO3)][CH3SO3] (1), [Zn(DMEGqu)(CH3SO3)2] (2) and [Zn(DMEGqu)2(CH3SO3)][CH3SO3] (3) were synthesised, completely characterised and investigated on their activity in the solvent‐free ring‐opening polymerisation of D,L‐lactide. It was proven that the bis‐chelate trigonal‐bipyramidally coordinated compounds 1 and 3 are able to act as initiators for lactide polymerisation, and polylactides with molecular weights (Mw) of around 28000 g/mol could be obtained with relatively narrow polydispersities. The tetrahedral complex 2 does not initiate lactide polymerisation. In an integrated approach of structural studies and DFT calculations, the active complexes 1 and 3 were analysed towards their structural and electronical pre‐requisites in comparison to their more active triflate analogues 1OTf and 3OTf. The influence of coordination strength of the anionic component on the charge distribution within the complex and on the substrate accessibility to the zinc centre is highlighted as crucial factor for the polymerisation initiation. As result, it is shown that the mesylate complexes 1 and 3 have less positive charge on the zinc centre and the mesylate is stronger bound than the corresponding triflate in the triflate complexes 1OTf and 3OTf. Consequently, the reactivity of the complexes is directly correlated to the coordinational behaviour of the anionic component.
Graft Copolymers Based on Functional Polyesters
Authors: Hahn Christian , Keul Helmut , Möller Martin 
Published: November 2010

AbstractGraft copolymers with a polyester backbone and PMMA side chains were successfully prepared in a two and a three step approach. In the two step approach, functional polyesters were prepared via polycondensation using hexane diol and bromosuccinic acid as building blocks and methyl methacrylate (MMA) was grafted from the resulting poly(hexamethylene bromosuccinate) (PHMBS), here the initiating group is linked directly to the polyester backbone.In the second approach hexane diol and malic acid were used as bilding blocks giving poly(hexamethylene malate) (PHMM). The hydroxyl groups of PHMM were transferred with 2‐bromo‐2‐propionylbromide into an ATRP‐initiator. Then the grafting of MMA from poly(hexamethylene malate) bromopropionate (PHMM‐BrP) was investigated.
Investigation of Calcium Carbonates Enhanced Poly(ε‐caprolactone) Materials for Biomedical Applications
Authors: Oláh László , Tuba Ferenc 
Published: November 2010

AbstractIn this study poly(ε‐caprolactone) – calcium‐carbonate composites were obtained by melt‐mixing. Two crystal‐modifications of calcium‐carbonate were used, namely calcite and aragonite. Compressive and tensile tests were executed on samples with various compositions to analyze the effect of filler content and particle geometry. Both minerals improved the compressive modulus and strength significantly, however the influence of calcite was superior. The tensile modulus was also highly increased. The elongation at break remained high even at 50 wt% aragonite filling, but decreased with two orders in the case of calcite. Biocompatibility tests were also carried out with human osteoblast cells and the results were promising. The relative cell number increased due to calcium‐carbonate. Both filler material is able to enhance the mechanical and biological properties of poly(ε‐caprolactone) significantly. Aragonite samples remained more ductile compared to calcite ones, but the calcite filled scaffolds are stiffer, stronger and slightly more biocompatible than aragonite filled materials.