bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerisation of Butyl acrylate in the two Phase Slug Flow Regime of Parallel Microcapillary Reactors
Authors: Mendorf M. , Moenter A. , Moll T. , Agar D.W. , Tiller J. 
Published: March 2011

AbstractSummary:The potential and problems of conducting a free radical polymerisation in parallel capillary reactors are presented. By operating in the so‐called slug flow regime of immiscible liquid‐liquid flow, one can achieve perfectly uniform residence times which are inaccessible using single phase flow. The excellent performance available in microreactors can be exploited for higher throughputs through the simple expedient of numbering‐up, i.e. operation of multiple similar reactors in parallel under identical hydrodynamic conditions. In practice this approach often comes to grief on the coupling between hydrodynamics and chemical reaction, for example due to the strong influence of polymerisation on viscosity. Rigorous modeling reveals that the operating conditions sought are actually unstable. Furthermore, the uniformity of flow distribution between parallel capillaries was found to be very sensitive to the manufacturing tolerances of the capillaries used in the presence of polymerisation. Two strategies for resolving such problems are discussed. In the first case, coupling between reaction and the flow distribution is suppressed by a sufficiently high pressure drop upstream of the temperature regulated reactor segments. The pressure drop necessary to achieve this decoupling was estimated by the model. An alternative technique involves an appropriately inexpensive flow control system for each individual capillary. Since commercially available microvalves and flow measurement equipment are too costly for parallelisation purposes, it is necessary to develop new components to fulfill these functions. An optical monitoring technique is presented that meets both the technical and economic criteria, and which can be readily combined with recently developed new micro valves.1
Risk Analysis in Transport and Storage of Monomers: An Accident Investigation
Authors: Casson Valeria , Maschio Giuseppe 
Published: March 2011

AbstractSummary: In this work the analysis of an accident in transport of dangerous goods is proposed. The objective of this study is to contribute to the determination of the causes that brought about the self‐polymerization of commercial divinylbenzene (DVB 63%) contained in an iso‐container, in order to prevent this accident to happen in the future. Time and conditions during transport and storage of monomers (in particular the storage temperature) are very important factors, that affect the self‐polymerization aptitude of these substances. To stabilize this monomer, usually 4‐tert‐Butylcatechol (TBC) is added at a level of 900–1200 ppm by weight to act as an inhibitor to prevent the self‐initiated autopolymerization of the material. In particular one hypothesis has been investigated: probably the quantity of oxygen in the tanker was insufficient to activate properly the inhibition mechanism of TBC. From this consideration the self‐polymerization of DVB and the inhibition mechanism of TBC have been studied as a function of temperature and monomer exposure to air. Different calorimetric techniques have been applied, in particular Differential Scanning Calorimetry and Adiabatic Calorimetry, to investigate the causes of the accident.
Modeling and Multiobjective Optimization of A Fed‐Batch Emulsion Copolymerization Process to Control the Resulting Particles Core‐Shell Morphology
Authors: Benyahia Brahim , Latifi Mohamed Abderrazak , Fonteix Christian , Pla Fernand 
Published: March 2011

AbstractSummary: This paper deals with the design and control of the morphology of core‐shell nanoparticles elaborated by fed‐batch emulsion copolymerization of styrene and butyl‐acrylate in the presence of a chain transfer agent (n‐dodecyl mercaptan). A mathematical model was elaborated and validated. It consists of a system of differential algebraic equations involving 49 unknown kinetic and thermodynamic parameters, many of them being impossible to be accurately estimated, due to the lack of experimental data. A method based on the sensitivity analysis allowed us to determine a subset of the 21 most influential parameters. The 28 non estimable parameters were taken from the literature. The validated model was then used in a dynamic multiobjective optimization to optimize the best profile of the pre‐emulsion feed rate to control (i) the composition and average molar masses of the copolymer, (ii) the instantaneous glass transition temperature, corresponding to a core‐shell morphology suited for special end‐use properties.
Diffusion Transport in Reconstructed Semi‐Crystalline Structure of Polyolefins
Authors: Hajová Hana , Pokorný Richard , Kosek Juraj 
Published: March 2011

AbstractSummary: Diffusion of penetrants (e.g., monomers) in polyolefins is important not only in their manufacturing and down‐stream processing, but also in packaging and separation applications. We propose a general methodology linking the semi‐crystalline structure of polyolefins to their application properties. This methodology comprises of AFM imaging of semi‐crystalline structure, reconstruction of 3D replica of semi‐crystalline polymer and calculation of application properties (e.g., diffusivity) depending on 3D morphology. Our algorithm is capable to achieve realistic crystallinities of reconstructed samples up to 70% and to reconstruct spherulites with preferential orientation of lamellae. We demonstrate and discuss difficulties experienced during AFM imaging of HDPE morphology, particularly the dependence of resulting AFM image representing the distribution of crystalline domains on the sample preparation including etching.
The Synthesis of Special Block Copolymers Using a Reaction Calorimeter
Authors: Weber Nancy , Texter John , Tauer Klaus 
Published: March 2011

AbstractSummary: The paper provides experimental results about an easy and versatile method to produce amphiphilic block copolymers, block copolymer particles, and even inorganic – polymeric nano‐composites via aqueous heterophase polymerization. Special emphasis is placed on the morphology and colloidal properties of some non‐ionic di‐ and triblock copolymer particles with poly(ethylene glycol) of 106 g/mol molecular weight as hydrophilic block as well as di‐stimuli‐responsive block copolymers containing both a poly(N‐isopropyl acrylamide) and a poly(ionic liquid) block.
Experimental Investigation and Numerical Simulation of Spray Processes
Authors: Laackmann Julian , Säckel Winfried , Cepelyte Lina , Walag Kamil , Sedelmayer Robert , Keller Franz , Pauer Werner , Moritz Hans‐Ulrich , Nieken Ulrich 
Published: March 2011

AbstractSummary: Acoustic levitation was investigated as a model for spray processes. The influence of different parameters on the drying process of aqueous polyvinylpyrrolidone (PVP) solutions was studied and compared to the evaporation of water. The adequacy of acoustic levitation as model for spray processes was demonstrated. Experiments with water and aqueous PVP solutions indicated no dependency of the droplet size on the drying process for droplets with a diameter between 300 µm and 1.5 mm. Particles dried in an acoustic levitator displayed good accordance of morphology with those obtained in a spray tower. Surprisingly the addition of PVP to water resulted in faster evaporation of the solvent. Mathematical models of single droplets within a spray process typically refer to spherically symmetric droplet geometries. The simulation of other morphologies and their evolution throughout the process is still very challenging. A new drying model based on a fully three‐dimensional meshfree approach is under development and shows good agreement to basic established models regarding the drying of a single droplet.
Macromolecular Crowding and the Sizes of Neutral Flexible Polymer Chains: The Role of Colloids Sizes and Concentrations
Authors: Ramos Ésio Bessa 
Published: March 2011

AbstractIn the present work, we revisit the effect of macromolecular crowding on the sizes of flexible neutral polymer chains. Motivated by recent experimental measurements on crowding effects on neutral flexible polymers chains, we perform Monte Carlo simulations on a model system consisting of hard spheres (HS) and a neutral flexible polymer chain. We find that, depending on the ratio of the sizes of the colloidal particles to the sizes of the polymer chain, and thus, on the extent of the colloid partitioning among the chain segments and the solution, the flexible polymeric coil may be either continuously compressed, or initially compressedfollowed by a reswellingat high enough colloid concentration. The chain behavior is thusnonmonotonic, a point which, apart from the work of Khalatur et al., has not so far been stressed in simulations of flexible polymer chains under crowding conditions. A thermodynamic model for the polymer–colloid interactions based on the Gibbs–Duhem equation and on a “Flory‐type” argument is also presented, emphasizing the indirect influence of macromolecular crowding on the monomers chemical potential. We show explicitly that under crowding conditions, the colloids are driven into the most compact coil states. These analytical results are compared with the results of the potential of mean force between the chain center of mass and the colloids obtained from the Monte Carlo simulations, and a reasonable agreement is found. The implications of the aforementioned results are further discussed in the context of biological systems, specially those for which macromolecular crowding is supposed to play the important role of including preferentially other (charged) macromolecules into the colloid‐compressed polymer phase.magnified image
In Silico Prediction of Caco‐2 Cell Permeability by a Classification QSAR Approach
Authors: Pham The Hai , González‐Álvarez Isabel , Bermejo Marival , Mangas Sanjuan Victor , Centelles Inmaculada , Garrigues Teresa M. , Cabrera‐Pérez Miguel Ángel 
Published: March 2011

AbstractIn the present study, 21 validated QSAR models that discriminate compounds with high Caco‐2 permeability (Papp≥8×10−6 cm/s) from those with moderate‐poor permeability (Papp<8×10−6 cm/s) were developed on a novel large dataset of 674 compounds. 20 DRAGON descriptor families were used. The global accuracies of obtained models were ranking between 78–82 %. A general model combining all types of molecular descriptors was developed and it classified correctly 81.56 % and 83.94 % for training and test sets, respectively. An external set of 10 compounds was predicted and 80 % was correctly assessed by in vitro Caco‐2 assays. The potential use of the final model was evaluated by a virtual screening of a human intestinal absorption database of 269 compounds. The model predicted 121 compounds with high Caco‐2 permeability and the 90 % of them had high values of human intestinal absorption (HIA≥80). This study provides the most comprehensive database of Caco‐2 permeability and evidenced the utility of the combined methodology (in silico+in vitro) in the prediction of Caco‐2 permeability. It suggests that the present methodology can be used in the design of large libraries of compounds with appropriate values of permeability and to perform virtual screening in the early stages of drug development.
MHC Class II Binding Prediction by Molecular Docking
Authors: Atanasova M. , Dimitrov I. , Flower D. R. , Doytchinova I. 
Published: March 2011

AbstractProteins of the Major Histocompatibility Complex (MHC) bind self and nonself peptide antigens or epitopes within the cell and present them at the cell surface for recognition by T cells. All T‐cell epitopes are MHC binders but not all MCH binders are T‐cell epitopes. The MHC class II proteins are extremely polymorphic. Polymorphic residues cluster in the peptide‐binding region and largely determine the MHC’s peptide selectivity. The peptide binding site on MHC class II proteins consist of five binding pockets. Using molecular docking, we have modelled the interactions between peptide and MHC class II proteins from locus DRB1. A combinatorial peptide library was generated by mutation of residues at peptide positions which correspond to binding pockets (so called anchor positions). The binding affinities were assessed using different scoring functions. The normalized scoring functions for each amino acid at each anchor position were used to construct quantitative matrices (QM) for MHC class II binding prediction. Models were validated by external test sets comprising 4540 known binders. Eighty percent of the known binders are identified in the best predicted 15 % of all overlapping peptides, originating from one protein.
Sensitivity and lineshape improvement in ultrafast 2D NMR by optimized apodization in the spatially encoded dimension
Authors: Giraudeau Patrick , Akoka Serge 
Published: March 2011

AbstractUltrafast 2D NMR allows the acquisition of a 2D spectrum in a single scan. However, even when the acquisition of ultrafast spectra is carried out under optimized conditions, the appearance and the sensitivity of 2D spectra are often not satisfactory compared with what one could expect from this promising methodology. This is due to limitations in terms of sensitivity, spectral width and resolution, and also to non‐ideal lineshapes characterized by asymmetric sinc wiggles. Here, we identify the origin of these distortions by means of numerical simulations compared with experimental data. We then propose a processing approach to improve lineshapes while increasing the sensitivity of ultrafast experiments. The method consists in multiplying the Fourier transform of ultrafast echoes by an optimized apodization function. The principles of the method are described, and a variety of window functions are tested to determine optimum processing conditions. The approach is finally applied to ultrafast 2D spectra, leading to symmetric lineshapes with a sensitivity increased by a factor of 2. Copyright © 2011 John Wiley & Sons, Ltd.
The observed and calculated 1H and 13C chemical shifts of tertiary amines and their N‐oxides
Authors: Pohl Radek , Dračínský Martin , Slavětínská Lenka , Buděšínský Miloš 
Published: March 2011

AbstractA series of model tertiary amines were oxidized in situ in an NMR tube to amine N‐oxides and their 1H and 13C NMR spectra were recorded. Next, the chemical shifts induced by oxidation (Δδ) were calculated using different GIAO methods investigating the influence of the method [Hartree‐Fock (HF), Moeller‐Plesset perturbation, density functional theory (DFT)], the functional applied in the DFT (B3LYP, BPW, OPBE, OPW91) and the basis set used [6‐31G*, 6‐311G**, 6‐311 + + G** and 6‐311 + + G(3df,3pd)]. The best results were obtained with the HF/6‐311 + + G** and OPBE/6‐311 + + G** methods. The computation/experiment comparison approach was used for the configuration prediction of chiral amine N‐oxides—(R) and (S)‐agroclavine‐6‐N‐oxide. Copyright © 2011 John Wiley & Sons, Ltd.
Structure elucidation of casbane diterpenes from Croton argyrophyllus
Authors: Silva‐Filho Francisco Artur e , Braz‐Filho Raimundo , Silveira Edilberto Rocha , Lima Mary Anne Sousa 
Published: March 2011

AbstractTwo novel casbane diterpenes 1‐hydroxy‐(2E,6Z,12E)‐casba‐2,6,12‐triene‐4,5‐dione (1) and 6E,12E‐casba‐1,3,6,12‐tetraen‐1,4‐epoxy‐5‐one (2) were isolated from the ethanol extract of the stems of Croton argyrophyllus. Structural characterization including the relative stereochemistry of all compounds was established on the basis of spectroscopic methods, mainly 1D and 2D NMR, and HRESIMS. Copyright © 2011 John Wiley & Sons, Ltd.
HSQC‐ADEQUATE: an investigation of data requirements
Authors: Martin Gary E. , Hilton Bruce D. , Willcott M. Robert , Blinov Kirill A. 
Published: March 2011

AbstractUtilizing 13C‐13C connectivity networks for the assembly of carbon skeletons from HSQC‐ADEQUATE spectra was recently reported. HSQC‐ADEQUATE data retain the resonance multiplicity information of the multiplicity‐edited GHSQC spectrum and afford a significant improvement in the signal‐to‐noise (s/n) ratio relative to the 1,1‐ADEQUATE data used in the calculation of the HSQC‐ADEQUATE spectrum by unsymmetrical indirect covariance (UIC) processing methods. The initial investigation into the computation of HSQC‐ADEQUATE correlation plots utilized overnight acquisition of the 1,1‐ADEQUATE data used for the calculation. In this communication, we report the results of an investigation of the reduction in acquisition time for the 1,1‐ADEQUATE data to take advantage of the s/n gain during the UIC processing to afford the final HSQC‐ADEQUATE correlation plot. Data acquisition times for the 1,1‐ADEQUATE spectrum can be reduced to as little as a few hours, while retaining excellent s/n ratios and all responses contained in spectra computed from overnight data acquisitions. Concatenation of multiplicity‐edited GHSQC and 1,1‐ADEQUATE data also allows the interrogation of submilligram samples with 1,1‐ADEQUATE data when using spectrometers equipped with 1.7‐mm Micro CryoProbes ™. Copyright © 2011 John Wiley & Sons, Ltd.
NQR study of chalcogenide glasses Ge‐As‐Se
Authors: Glotova Olga , Korneva Irina , Sinyavsky Nikolay , Ostafin Michal , Nogaj Boleslaw 
Published: March 2011

AbstractA three‐component Ge‐As‐Se system is studied by the nuclear quadrupole resonance (NQR) method on 75As nuclei and by the nutation NQR spectroscopy. The NQR 75As spectra of the glasses Ge0.021As0.375Se0.604, Ge0.043As0.348Se0.609 and Ge0.068As0.318Se0.614reveal broad lines with two peaks assigned to the main structural unit of As2Se3. With increasing average coordination number (r̄), the spectrum signals are shifted towards higher frequencies. At r̄ > 2.54, the spectrum becomes complex, which is a consequence of formation of more complex molecular structures in the glasses of high content of germanium. At fixed frequencies the asymmetry parameter η of the samples studied is determined. Copyright © 2011 John Wiley & Sons, Ltd.
DFT calculations of 31P spin–spin coupling constants and chemical shift in dioxaphosphorinanes
Authors: Pecul Magdalena , Urbańczyk Mateusz , Wodyński Artur , Jaszuński Michał 
Published: March 2011

AbstractOne‐bond heteronuclear spin‐spin coupling constants 1JPX (XH, O, S, Se, C and N) between the phosphorus atom and axial and equatorial substituents in dioxaphosphorinanes are computed using density functional theory (DFT). The experimental values of these coupling constants for a variety of substituents can be applied to identify different diastereoisomers. The DFT calculations confirm the systematic trend observed in experiment, and indicate that the computed 1JPX coupling constants are related to the length of the axial and equatorial bonds. A similar relation between the phosphorus chemical shift and the R(PX) bond length appears to be valid, with the exception of selenium substituents. Copyright © 2011 John Wiley & Sons, Ltd.
Body mass index, not dyslipidemia, is an independent predictor of survival in amyotrophic lateral sclerosis
Authors: Paganoni Sabrina , Deng Jing , Jaffa Matthew , Cudkowicz Merit E. , Wills Anne‐Marie 
Published: March 2011

AbstractIntroduction: Recent studies have provided conflicting data regarding the role of dyslipidemia in amyotrophic lateral sclerosis (ALS). The aim of this study was to determine whether cholesterol level are an independent predictor of survival in ALS. Methods: Cholesterol levels were measured in 427 ALS subjects from three clinical trial databases. Results: The LDL/HDL ratio did not decrease over time, despite significant declines in body mass index (BMI), forced vital capacity (FVC), and ALSFRS‐R. After adjusting for BMI, FVC, and age, the lipid ratio was not associated with survival. There was a “U”‐shaped association between BMI and mortality, with the highest survival at 30–35 kg/m2. The adjusted hazard ratio for the linear association between BMI and survival was 0.860 (95% CI 0.80–0.93, P = 0.0001). Conclusions: We found that dyslipidemia is not an independent predictor of survival in ALS. BMI is an independent prognostic factor for survival after adjusting for markers of disease severity. Muscle Nerve, 2011
Association of common variants in the human eyes shut ortholog (EYS) with statin‐induced myopathy: Evidence for additional functions of EYS
Authors: Isackson Paul J. , Ochs‐Balcom Heather M. , Ma Changxing , Harley John B. , Peltier Wendy , Tarnopolsky Mark , Sripathi Naganand , Wortmann Robert L. , Simmons Zachary , Wilson Jon D. , Smith Stephen A. , Barboi Alexandru , Fine Edward , Baer Alan , Baker Steven , Kaufman Kenneth , Cobb Beth , Kilpatrick Jeffrey R. , Vladutiu Georgirene D. 
Published: March 2011

AbstractIntroduction: Of the nearly 38 million people in the USA who receive statin therapy, 0.1‐0.5% experience severe or life‐threatening myopathic side effects. Methods: We performed a genome‐wide association study (GWAS) in a group of patients with severe statin myopathy versus a statin‐tolerant group to identify genetic susceptibility loci. Results: Replication studies in independent groups of severe statin myopathy (n = 190) and statin‐tolerant controls (n = 130) resulted in the identification of three single‐nucleotide polymorphisms (SNPs), rs9342288, rs1337512, and rs3857532, in the eyes shut homolog (EYS) on chromosome 6 suggestive of an association with risk for severe statin myopathy (P = 0.0003–0.0008). Analysis of EYS cDNA demonstrated that EYS gene products are complex and expressed with relative abundance in the spinal cord as well as in the retina. Conclusion: Structural similarities of these EYS gene products to members of the Notch signaling pathway and to agrin suggest a possible functional role in the maintenance and regeneration of the structural integrity of skeletal muscle. Muscle Nerve, 2011
Confirmation of the severe phenotypic effect of serine at codon 41 of the superoxide dismutase 1 gene
Authors: Subramony S. H. , Ashizawa Tetsuo , Langford Leigh , Mckenna Robert , Avvaru Balu , Siddique Teepu , Vedanarayanan V. 
Published: March 2011

AbstractIntroduction: A Gly41Ser mutation in the superoxide dismutase 1 gene (SOD1) has been reported to cause a very rapid course of amyotrophic lateral sclerosis (ALS) in a limited number of Italian patients, but a Gly41Asp mutation results in a more benign course. Methods: Four members of an African American family with autosomal dominant ALS were evaluated clinically over 12 years. Mutation analysis of SOD1 was done on 1 patient. Results: All patients had a pure lower motor neuron syndrome with onset to death in 9–15 months. A Gly41Ser mutation in SOD1 was established. In silico modeling suggested that this mutation can have a more deleterious effect than a Gly41Asp mutation. Conclusion: The more rapid course of ALS with the Gly41Ser SOD1 mutation is confirmed in a distinct ethnic group. Muscle Nerve, 2011
Evaluation of spinal and bulbar muscular atrophy by the clustering index method
Authors: Higashihara Mana , Sonoo Masahiro , Yamamoto Tomotaka , Nagashima Yu , Uesugi Haruo , Terao Yasuo , Ugawa Yoshikazu , Stålberg Erik , Tsuji Shoji 
Published: March 2011

AbstractIntroduction: A reliable electrophysiological marker for clinical trials is increasingly needed in spinal and bulbar muscular atrophy (SBMA). We previously developed a quantitative analysis method for surface electromyography (SEMG), the clustering index (CI) method. Our purpose was to test the utility of the CI method for evaluating lower motor neuron involvement in SBMA patients. Methods: Subjects included 29 SBMA patients and 27 healthy controls. The recording electrode was placed over the abductor digiti minimi (ADM) muscle with a proximal reference. The Z‐score, based on the CI method, was compared with compound muscle action potential (CMAP) amplitude and motor unit number estimation (MUNE), with regard to sensitivity. Results: The Z‐scores of the CI method, CMAP amplitude, and MUNE were abnormal in 100%, 72%, and 93% of the patients, respectively. Interrater reliability of the CI method was sufficiently high. Conclusion: The CI method is promising as a non‐invasive electrophysiological marker in SBMA. Muscle Nerve, 2011