bluuebunny/crossref_metadata_2025 huggingface dataset:
Online Model‐Based Process Safety Concepts in Polymerization
Authors: Manders Lambertus G. , Meister Martin , Bausa Jens , Hungenberg Klaus‐Dieter
Published: March 2011

Summary: To safeguard runaway reactions in industrial scale, qualified methods have to be used. While mechanical safety devices are usually installed, their design may be problematic as the runaway kinetics must be known. This may not be the case for many processes due to the required flexibility and possible unanticipated deviations from recipes. It is shown that runaway kinetics can be very fast and can lead to high conversions. Therefore, a method is proposed that does not depend on kinetics but limits the amounts of unreacted monomer in the reactor by monitoring the conversion and by quantitatively determining the hazardous potential. If a potential violation is observed, feeds to the reactor are interrupted.
Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide
Authors: Aerts Marijke , Meuldijk Jan , Kemmere Maartje , Keurentjes Jos
Published: March 2011

Summary: Extraction of residual monomer from a latex product with supercritical carbon dioxide ((sc)CO2) in a column was studied. Operating conditions were chosen at 35 °C and 100 bar. For reducing the residual styrene level in a polystyrene latex from 104 ppm to 100 ppm and from 104 ppm to 10 ppm, a countercurrent bubble column with latex as continuous and (sc)CO2 as dispersed phase is suggested. Monomer partitioning was demonstrated to be a key parameter in the equipment design. Monomer transport was found to be governed by the shuttle effect, caused by Brownian motion of the latex to and from the H2O/CO2 interface. The drift‐flux approach was followed to determine the column flooding conditions. Small column volumes are obtained. (sc)CO2 is a promising extraction medium for residual monomer reduction in latex products. Performance towards steam stripping is better as the final residual monomer level becomes lower.
Activity Monitoring for a Polymerization Catalyst System
Authors: Tracht Ursula , Leiberich Ricarda , Wiesner Udo , Paul Hanns‐Ingolf
Published: March 2011

Summary: Catalyst systems for polymerization often exhibit variable and poorly controllable activity because of strong influences of trace components and catalyst preparation conditions. In cationic polymerizations in particular, determining catalytic activity and hence the amount of catalyst to be used is challenging. The assessment of a given initiator system typically requires testing it in polymerization reactions. Determining catalytic activity before using the initiator in a polymerization reaction is a desirable approach. This contribution describes the development of such an activity monitoring tool. In the first part, results from a fundamental characterization of the system diethylaluminum chloride/ethylaluminum dichloride/water by different NMR measurements and elemental analysis are reported. Structures characteristic of catalytically active systems are presented. The second part describes the application of transmission IR to the characterization of this system and the correlation of IR results to catalytic activity in dimerization and polymerization reactions. Implementation of the IR analysis as an on‐line measurement is demonstrated.
Characterization and Miscibility Dynamics of Dextran‐Poly(vinylpyrrolidone)‐Water System
Authors: Mete Dilek , Göksel Cemile , Güner Ali
Published: March 2011

Summary: The miscibility behavior and intermolecular interactions among Dextran (Dx) with different molecular weight and Polyvinylpyrrolidone (PVP) blends were studied as dilute aqueous solutions at 25 °C by viscosity method. The intrinsic viscosity and the interaction coefficient were experimentally measured for each polymer‐water as well as for Dx‐PVP‐water systems. These results served for the prediction of miscibility of the Dx/PVP blends with various blend compositions by using$\Delta {\left[ {\eta } \right]}_{m} $,$\Delta b_{m} $,$\Delta k_{AB} $,$\Delta B$,$\mu $ and $\alpha $ parameters. Except Dx4/PVP with its all compositions (Dx4 with nominal molecular weight of 110 000), other blend systems are found to be almost miscible. The density measurements of these polymer solutions and their blends were conducted in order to compare with the viscosity findings. Lastly, all Dx with different molecular weight, PVP and their blends were characterized by infrared spectroscopy (FT‐IR), and differential scanning calorimetry (DSC).
Industrial Polymerization Monitoring
Authors: Frauendorfer Eric , Hergeth Wolf‐Dieter
Published: March 2011

Summary: Monitoring and control of polymerization reactions is essential for high process safety, high product quality and competitive production costs. Ideally the entire process chain is regarded, starting with raw material analysis and the polymerization reaction up to the measurement of polymer‐ and application‐ properties. Process data like temperatures and pressures can be used to monitor reaction trajectories in a cost effective way, e.g. using calorimetric evaluations. Additional sensors can provide chemical or morphological information but must be robust and inexpensive for commercial applications (e.g. NIR‐ or Raman spectroscopy). Data from these different sources can be used for multivariate data analysis, delivering additional insights that might not be obtained by direct measurement.
Needs and Opportunities – Molecular Modeling Meets Polymer Process Modeling
Authors: Weiss Horst , Deglmann Peter
Published: March 2011

Summary:A non‐exhaustive and somehow arbitrary review on actual trends and remaining challenges for a model based process development is given. An example how state of the art molecular modeling methods help to provide kinetic information is explained in some detail. A brief sketch of various methods providing thermodynamic information for engineering is given, and finally, recent concurrent coupling schemes of particle based simulation and computational fluid dynamics are highlighted.
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

Summary: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

Summary: 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

Summary: 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

Summary: 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

Summary: 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

Summary: 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

In 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.

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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

In 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

Proteins 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

Ultrafast 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

A 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

Two 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

Utilizing 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

A 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

One‐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

Introduction: 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

Introduction: 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

Introduction: 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

Introduction: 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
Is sour crude or sour gas a potential source of Se and Te?
Authors: Green Martin A.
Published: March 2011

Increasing dependence on high sulphur ‘sour’ crude oil combined with increasingly stringent requirements on the sulphur content of processed fuels has rapidly made sour crude and sour gas the major commercial sources of sulphur. Production is outstripping demand, resulting in large S stockpiles. Since other chalcogens, Se and Te in particular, could be concentrated by the same processes that concentrate S, sour crude has been suggested as a possible source of Te for photovoltaics. The possibilities are explored for both Se and Te in the present paper. Suppressed concentrations of Se in crude oil and gas relative to sulphur and the even lower likely concentrations of Te mitigate against this prospect. Copyright © 2011 John Wiley & Sons, Ltd.
Novel clues on abiotic stress tolerance emerge from embryo proteome analyses of rice varieties with contrasting stress adaptation
Authors: Farinha Ana P. , Irar Sami , de Oliveira Eliandre , Oliveira M. Margarida , Pagès Montserrat
Published: March 2011

Cereal embryos sustain severe water deficit at the final stage of seed maturation. The molecular mechanisms underlying the acquisition of desiccation tolerance in seed embryos are similar to those displayed during water deficit in vegetative tissues. The genetic variation among six rice genotypes adapted to diverse environmental conditions was analysed at the proteome level to get further clues on the mechanisms leading to water‐stress tolerance. MS analysis allowed the identification of 28 proteins involved in stress tolerance (late embryogenesis abundant proteins), nutrient reservoir activity, among other proteins implicated in diverse cellular processes potentially related to the stress response (e.g., mitochondrial import translocase). Hierarchical clustering and multidimensional scaling analyses revealed a close relationship between the stress‐sensitive genotypes, whereas the stress‐tolerant varieties were more distantly related. Besides qualitative and significant quantitative changes in embryo proteins across the distinct varieties, we also found differences at post‐translational level. The results indicated that late embryogenesis abundant Rab21 was more strongly phosphorylated in the embryos of the sensitive varieties than in the embryos of the tolerant ones. We propose that the differences found in the phosphorylation status of Rab21 are related to stress tolerance.
Genomic and proteomic characterization ofStaphylococcus aureusmastitis isolates of bovine origin
Authors: Wolf Carmen , Kusch Harald , Monecke Stefan , Albrecht Dirk , Holtfreter Silva , von Eiff Christof , Petzl Wolfram , Rainard Pascal , Bröker Barbara M. , Engelmann Susanne
Published: March 2011

Staphylococcus aureuscolonizes and infects humans as well as animals. In the present study, 17S. aureusstrains isolated from cows suffering from mastitis were characterized. The well‐established multilocus sequence typing (MLST) technique and a diagnostic microarray covering 185S. aureusvirulence and resistance genes were used for genetic and epidemiological analyses. Virulence gene expression studies were performed by analyzing the extracellular protein pattern of each isolate on 2‐D gels. By this way, a pronounced heterogeneity of the extracellular proteome between the bovine isolates has been observed which was attributed to genome plasticity and variation of gene expression. Merely 12 proteins were expressed in at least 80% of the isolates, i.e. Atl, Aur, GlpQ, Hla, LtaS, Nuc, PdhB, SAB0846, SAB2176, SAB0566, SspA, and SspB forming the core exoproteome. Fifteen extracellular proteins were highly variably expressed and only present in less than 20% of the isolates. This includes the serine proteases SplB, C, and F, and the superantigens SEC‐bov, SEL and TSST‐1. Compared to human isolates we identified at least six proteins with significantly different expression frequencies. While SAB0846 was expressed more frequently in bovine isolates, LytM, EbpS, Spa, Geh, and LukL1 were seen less frequently in these isolates.
Female urinary proteomics: New insight into exogenous and physiological hormone‐dependent changes
Authors: Castagna Annalisa , Olivieri Oliviero , Milli Alberto , Dal Bosco Miriam , Timperio Anna Maria , Zolla Lello , Gunasekaran Muthukumar , Raffaelli Ricciarda , Pizzolo Francesca , Cecconi Daniela
Published: March 2011

Purpose: In the frame of a research study on possible urinary markers related to physiological hormones cycle, 33 volunteer, healthy, normotensive fertile women were selected. Clinical parameters and renin–angiotensin–aldosterone system (RAAS) components were also investigated, on the basis of the well‐known relation linking sex female hormones and renin and aldosterone levels.

Experimental design: A classic proteomic approach was applied to investigate urinary protein changes at different stages of menstrual cycle, specifically mid‐cycle phase (G1), luteal phase (G2) and after 2 months of contraceptive therapy (G3). Analysis of urinary proteome was performed by SDS‐PAGE, 2‐D PAGE, Western blotting, and protein identification by HPLC‐MS/MS.

Results: In the four comparisons examined (G1 vs. G2; G1 vs. G3; G2 vs. G3 and G(G1+G2) vs. G3), a total of 115 protein spots were differentially represented among the subgroups. Data validation was performed by replicated experiments of immunoblotting.

Conclusions and clinical relevance: The present work highlights for the first time variations with menstrual cycle or estroprogestin pill of newly discovered, or never related, urinary proteins. In particular, possible protein markers could be useful for further applications in contraceptive target research and RAAS modulation‐related topics.
Human urinary peptide database for multiple disease biomarker discovery
Authors: Siwy Justyna , Mullen William , Golovko Igor , Franke Julia , Zürbig Petra
Published: March 2011

Purpose: Human urine is an ideal candidate for use in clinical diagnostics. It is easily available, as untrained personnel can collect it. It correlates well with the pathophysiology of a number of diseases, making it a useful source for clinical proteomics.

Experimental design: In this article, we give an update of the human urinary peptide database derived from over 13 000 data sets of CE‐MS by now.

Results: Urine samples from both patients and healthy subjects were analyzed by CE‐MS; these included 47 different pathophysiological conditions. Besides defining biomarkers by their experimental parameters, information on their sequences provides fundamental data into the pathological pathways of diseases. Therefore, we have sequenced 953 urinary peptides by using state‐of‐the‐art top‐down MS/MS. Identified biomarkers of all clinical proteomic CE‐MS studies including their regulation are also listed in this work.

Conclusions and clinical relevance: Biomarker discovery can be used in the management of a wide range of diseases, by combining these data sets of the database. Taking this approach, we can reveal details, at a molecular level, on the pathogenesis of a number of diseases, in particular those associated with urine production and excretion.
Improving color rendering of Y3Al5O12:Ce3+ white light‐emitting diodes based on dual‐blue‐emitting active layers
Authors: Chen Xian‐Wen , Zhang Yong , Li Shu‐Ti , Yan Qi‐Rong , Zheng Shu‐Wen , He Miao , Fan Guang‐Han
Published: March 2011

An InGaN/GaN blue‐violet light‐emitting diode (LED) structure and an InGaN/GaN blue LED structure were grown sequentially on the same sapphire substrate by metal‐organic chemical vapor deposition (MOCVD). At the low injection current, the intensity ratio of blue‐violet light to blue light was almost constant, while the blue light intensity increased gradually with increasing injection current when the latter was more than 40 mA. High color rendering has been realized for a Y3Al5O12:Ce3+ phosphor‐converted white LED based on dual‐blue‐emitting active layers relative to a single blue‐emitting active layer at the same injection current.
First‐principles study on the structural, phonon, and thermodynamic properties of the ternary carbides in Ti–Al–C system
Authors: Chen Yang , Chu Maoyou , Wang Lijun , Bao Xinhua , Lin Yang , Shen Jianyun
Published: March 2011

The structural, phonon, and thermodynamic properties of the ternary carbides Ti2AlC, Ti3AlC, and Ti3AlC2 in the Ti–Al–C system are investigated by using first‐principles calculations in this paper. Phonon dispersion curves and partial density of states have been investigated and revealed the different Ti–C bond characteristics between Ti3AlC and the two other compounds. The Gibbs energy, entropy, heat capacity, and thermal expansion coefficient of the three compounds are predicted by means of the quasi‐harmonic approximation. Furthermore, the thermal electronic contribution has been included in the thermodynamic properties. The obtained results of this study are in good agreement with the available experimental data.
Composition and orientation dependence of the interfacial energy in Fe–Cr stainless steel alloys
Authors: Lu Song , Hu Qing‐Miao , Johansson Börje , Vitos Levente
Published: March 2011

Using a first‐principles quantum mechanical method, we calculated the (001) and (110) interfacial energies between the low temperature α and α′ phases of Fe–Cr alloys as functions of chemical composition. We show that the interfacial energies and the interfacial energy anisotropy are highly composition dependent. In particular, the increasing interfacial energy anisotropy with decreasing compositional gap may induce different morphology of the decomposed phases for different compositions of the host alloys.
Analysis of interface states in Pd/n‐ GaN by temperature and frequency dependent admittance
Authors: Sellai Azzouz , Mamor Mohammed
Published: March 2011

The measured frequency‐dependent ac admittance over a range of temperatures (100 K–300 K) was used to obtain the admittance Gss + jωCss associated with the displacement current in the Pd/GaN interfacial layer. Using two methods based on C‐V data at two frequencies and conductance data over a wide range of frequencies, the interface states density is determined to be of the order of 1013 cm‐2 eV‐1 at room temperature and shows a slight increase with decreasing temperatures. The derived emission rates range mainly from 105 s‐1 to 106 s‐1 and are to some extent voltage and temperature dependent, showing a decrease with decreasing temperatures. The subsequently obtained capture cross‐sections are thermally activated with values varying from 10‐14to 10‐16 cm2 and reveal also a significant dependence on the applied forward bias. The density of interface states obtained in the ac regime is roughly in line with that previously derived from the ideality factor of the dc I‐V characteristics. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of GaN‐based light‐emitting diodes grown on vicinal sapphire substrates
Authors: Liu Yi‐Jung , Chen Huey‐Ing , Cheng Shiou‐Ying , Lin Kun‐Wei , Liu Wen‐Chau
Published: March 2011

GaN‐based light‐emitting diodes (LEDs) grown on c‐plane vicinal sapphire substrates are fabricated and characterized. All the electrical characteristics demonstrate that the LED with a 0.2° tilt sapphire substrate exhibits the lowest defect density while that with a 1.0° tilt sapphire exhibits the highest one. At 2 mA, the enhanced output power of 23.3% indicates the substantial reduction of defect‐related nonradiative recombination centers in MQW for the LED device with a 0.2°‐tilt sapphire. At 60 mA, the improved value is up to 45.7%. This is primarily caused by the presence of indium quantum dots (QDs) in MQW which provides increased quantum efficiency (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Longitudinal polar optical phonons in InN/GaN single and double het‐ erostructures
Authors: Ardali Sukru , Tiras Engin , Gunes Mustafa , Balkan Naci , Ajagunna Adebowale Olufunso , Iliopoulos Eleftherios , Georgakilas Alexandros
Published: March 2011

Longitudinal optical phonon energy in InN epi‐layers has been determined independently from the Raman spectroscopy and temperature dependent Hall mobility measurements. Raman spectroscopy technique can be used to obtain directly the LO energy where LO phonon scattering dominates transport at high temperature. Moreover, the Hall mobility is determined by the scattering of electrons with LO phonons so the data for the temperature dependence of Hall mobility have been used to calculate the effective energy of longitudinal optical phonons.The samples investigated were (i) single heterojunction InN with thicknesses of 1.08, 2.07 and 4.7 μm grown onto a 40 nm GaN buffer and (ii) GaN/InN/AlN double heterojunction samples with InN thicknesses of 0.4, 0.6 and 0.8 μm. Hall Effect measurements were carried out as a function of temperature in the range between T = 1.7 and 275 K at fixed magnetic and electric fields. The Raman spectra were obtained at room temperature. In the experiments, the 532 nm line of a nitrogen laser was used as the excitation source and the light was incident onto the samples along of the growth direction (c‐axis). The results, obtained from the two independent techniques suggest the following: (1) LO phonon energies obtained from momentum relaxation experiments are generally slightly higher than those obtained from the Raman spectra. (2) LO phonon energy for the single heterojunctions does not depend on the InN thickness. (3) In double heterostructures, with smaller InN thicknesses and hence with increased strain, LO phonon energy increases by 3% (experimental accuracy is < 1%) when the InN layer thickness increases from 400 to 800 nm (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties and phase transitions of CdS under high pressure and moderate temperature
Authors: He Chunyuan , Liu Bingguo , Zhang Dongmei , Gao Chunxiao
Published: March 2011

The electrical transport properties and phase transitions of CdS were investigated under high pressure and moderate temperature by a microcircuit fabricated on diamond anvil cell. Around 2.0 GPa the resistivity of CdS dropped two orders of magnitude sharply, implying a beginning of a phase transition from wurtzite phase to rock‐salt phase. At about 4.0 GPa the resistivity appeared a local minimum indicating an end of the transition to rock‐salt phase. A local maximum of the resistivity was observed at about 8.0 GPa, which was attributed to the changeover of indirect gap from Σν→Xc to Lν→Xc. Furthermore, two inflexions of resistivity were observed at about 16.0 GPa and 21.0 GPa, which predicting that the indirect band gap of CdS may further change at these pressures. In the range of experimental pressure and temperature CdS still showed the electrical transport property of a semiconductor. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The electrical properties of ZnTe under high pressure and moderate temperature
Authors: Cui Xiaoyan , Hu Tingjing , Yang Jie , Han Yonghao , Li Yan , Liu Cailong , Wang Yue , Liu Bao , Ren Wanbin , Su Ningning , Liu Hongwu , Gao Chunxiao
Published: March 2011

The resistivity of ZnTe powders has been measured under high pressure up to 29 GPa and temperature ranged from 303.0 to 403.0 K by using a diamond anvil cell. The resistivity changed discontinuously at 9.5 and 13.1 GPa, corresponding to the phase transitions from zinc blende to cinnabar and then to Cmcm structure. The decrease of activation energy by one order of magnitude indicates the deep‐to‐shallow transition of acceptor levels at 6.7 GPa. The resistivity decreases with temperature increasing indicates the semiconducting character of ZnTe in zinc blende phase. The resistivity of ZnTe in cinnabar phase decreases slightly with temperature increasing, indicating that this phase is a narrow‐gap semiconductor. After 19.1 GPa, the resistivity increases with temperature increasing, indicating the metallic character of Cmcm phase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effects of quantum well numbers and thermal annealing on optical properties of GaInNAs/GaAs quantum well structures
Authors: Basak H. , Erol A. , Donmez O. , Arikan M. C. , Saarinen M.
Published: March 2011

As‐grown and annealed Ga0.6In0.4N0.005As0.995/GaAs with 1, 3, and 7 quantum well structures grown by Molecular Beam Epitaxy (MBE) are investigated using Photoluminescence (PL) and Photo‐Induced Current Transient Spectroscopy (PICTS) measurements in order to determine the effects of the number of quantum wells and thermal annealing on optical properties and qualities of the structures. PICTS results reveal that all the samples with different quantum well numbers have two dominate trap levels which related to GaInNAs layer (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resonant soft X‐ray emission and X‐ray absorption studies on Ga1‐xMnxN grown by pulsed laser deposition
Authors: Krishnamurthy Satheesh , Kennedy Brian , McGee Fintan , Venkatesan M. , Coey J. M. D. , Lunney James G. , Learmonth Timothy , Smith Kevin E. , Schmitt Thorsten , McGuinness Cormac
Published: March 2011

In this study thin film samples of Ga1‐xMnxN were grown by pulsed laser deposition on Al2O3 (0001) substrates. X‐ray diffraction measurements have confirmed these thin films exhibit hexagonal wurtzite structure. SQUID measurements show room temperature ferromagnetism of these dilute magnetic semiconductors (DMS). The techniques of X‐ray absorption and soft X‐ray emission spectroscopy at the N K‐edge were used to study the changes in the unoccupied and occupied N 2p partial density of states respectively as a function of dopant concentration. These element and site specific spectroscopies allow us to characterise the electronic structure of these doped materials and reveal the influence of the Mn doping on the valence band as measured through the N 2p partial density of states. X‐ray absorption measurements at the Mn L‐edge confirm significant substitutional doping of Mn into Ga‐sites. Finally, measurements of heavily Mn‐doped films using both soft X‐ray absorption and resonant soft X‐ray emission at the N K edge reveal the presence of trapped molecular nitrogen. The trapped molecular nitrogen may be due to the high instantaneous deposition rate in the PLD process for these samples (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)