bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism
Authors: Castro Enrique A. , Ugarte Daniela , Rojas M. Fernanda , Pavez Paulina , Santos José G. 
Published: September 2011

AbstractThe reactions of diethyl 4‐nitrophenyl phosphate (1) with a series of nucleophiles: phenoxides, secondary alicyclic (SA) amines, and pyridines are subjected to a kinetic study. Under excess of nucleophile, all the reactions obey pseudo‐first‐order kinetics and are first order in the nucleophile. The nucleophilic rate constants (kN) obtained are pH independent for all the reactions studied. The Brønsted‐type plot (log kN vs. pKa nucleophile) obtained for the phenolysis is linear with slope β=0.21; no break was found at pKa 7.5, consistent with a concerted mechanism. The Brønsted‐type plots for the SA aminolysis and pyridinolysis are linear with slopes β=0.39 and 0.43, respectively, also suggesting concerted processes. The concerted mechanisms for the latter reactions are proposed on the basis of the lack of break in the Brønsted‐type plots and the instability of the hypothetical pentacoordinate intermediates formed in these reactions. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 708–714, 2011
Diffusion Coefficients in Thermosensitive Poly(NIPAAm) Hydrogels
Authors: Naddaf Aisha A. , Bart Hans‐Jörg 
Published: September 2011

AbstractDiffusion coefficients for the moving boundary thermosensitive poly(N‐isopropylacrylamide) hydrogels, which were swelled to equilibrium in aqueous solutions of either BSA or phenol, have been determined. Using a uniaxial compression apparatus the collective (Dcol) and with confocal Raman spectroscopy the mutual (Dmut) diffusion coefficients were estimated. The solute distribution in the hydrogel in addition to the effect of the swelling ratio, the cross‐linking ratio and the hydrogel cylinder thickness on the Young's modulus were investigated.
Explaining ADAGIO: A critical review of the biological basis for the clinical effects of rasagiline
Authors: Jenner Peter , Langston J. William 
Published: September 2011

AbstractThe ADAGIO study demonstrated a symptomatic benefit for rasagiline in early Parkinson's disease (PD) and suggested a disease‐modifying effect. Evidence indicates that mitochondrial dysfunction plays a role in the pathogenesis of PD and that this may be the site of effect for rasagiline. In this systematic review, evidence for the role of mitochondria in the pathogenesis of PD are reviewed in light of other proposed mechanisms of neuronal degeneration and the actions of rasagiline and its component parts, namely propargylamine and the metabolite, aminoindan. Evidence for the role of mitochondria in the pathogenesis and treatment of PD are reviewed in light of other proposed mechanisms of neuronal degeneration and clinical actions of rasagiline. Monoamine oxidase B (MAO‐B) located in the outer mitochondrial membrane controls dopamine metabolism in early PD, and this is the likely location for the symptomatic action of rasagiline. Accumulating evidence indicates that mitochondrial impairment contributes to dopaminergic neuronal loss in PD, either directly or through other mechanisms such as oxidative stress or protein misfolding. Further rasagiline affects numerous mitochondrial mechanisms that prevent apoptotic cell death including prevention of opening of the mitochondrial transition pore, decreased release of cytochrome C, alterations in pro‐antiapoptotic genes and proteins, and the nuclear translocation of glyceraldehyde 3‐phosphate dehydrogenase (GAPDH). Thus, the functional neuroprotective actions of rasagiline may not be dependent on MAO‐B inhibition, but rather may involve actions of the propargylamine moiety and the aminoindan metabolite. An accumulating body of literature indicates a mitochondrial site of action for rasagiline and highlights the neuroprotective action of the drug, providing strong biological plausibility for disease‐modifying effects of the drug such as those observed in ADAGIO. © 2011 Movement Disorder Society
Selecting Relevant Descriptors for Classification by Bayesian Estimates: A Comparison with Decision Trees and Support Vector Machines Approaches for Disparate Data Sets
Authors: Carbon‐Mangels Miriam , Hutter Michael C. 
Published: September 2011

AbstractClassification algorithms suffer from the curse of dimensionality, which leads to overfitting, particularly if the problem is over‐determined. Therefore it is of particular interest to identify the most relevant descriptors to reduce the complexity. We applied Bayesian estimates to model the probability distribution of descriptors values used for binary classification using n‐fold cross‐validation. As a measure for the discriminative power of the classifiers, the symmetric form of the Kullback–Leibler divergence of their probability distributions was computed. We found that the most relevant descriptors possess a Gaussian‐like distribution of their values, show the largest divergences, and therefore appear most often in the cross‐validation scenario. The results were compared to those of the LASSO feature selection method applied to multiple decision trees and support vector machine approaches for data sets of substrates and nonsubstrates of three Cytochrome P450 isoenzymes, which comprise strongly unbalanced compound distributions. In contrast to decision trees and support vector machines, the performance of Bayesian estimates is less affected by unbalanced data sets. This strategy reveals those descriptors that allow a simple linear separation of the classes, whereas the superior accuracy of decision trees and support vector machines can be attributed to nonlinear separation, which are in turn more prone to overfitting.
STRATEGIES FOR ENGAGEMENT: GOVERNMENT AND NATIONAL NON‐GOVERNMENT EDUCATION PROVIDERS IN SOUTH ASIA
Authors: Rose Pauline 
Published: September 2011

SUMMARYIt is often assumed that non‐government education providers prefer to operate without ‘interference’ from government. However, in practice, they inevitably need to form relationships. There is also a common view that non‐governmental organisations (NGOs) have to choose between service delivery and advocacy. As this article shows, these objectives are often not independent of each other. Drawing on evidence from established national non‐government education providers in Bangladesh, India and Pakistan, the article identifies different strategies adopted in balancing their service delivery and advocacy objectives. In all cases, the NGOs find ways to ensure a cooperative rather than conflictual relationship with government to pursue their goals. Strategies vary according to the strength of the national policy context, the formality of the relationship and the degree of dependence on funding sources, with the latter being most influential. Copyright © 2011 John Wiley & Sons, Ltd.
Comorbidities in an asthma population 8–29 years old: a study from the Norwegian Prescription Database
Authors: Karlstad Øystein , Nafstad Per , Tverdal Aage , Skurtveit Svetlana , Furu Kari 
Published: September 2011

ABSTRACTPurposeTo examine the occurrence of chronic diseases and antimicrobial treatment in an asthma population 8–29 years old, compared with the general population.MethodsIn this cross‐sectional study, the asthma population was identified from the general population (retrieved from a census covering the entire Norwegian population) using filled prescriptions on asthma drugs as a proxy measure of current asthma. The outcome was excess occurrence of specific diseases (comorbidity) among people with asthma, compared with the age‐specific general population. Diseases were defined by filled prescriptions with specific diagnostic codes (International Classification of Primary Care 2nd edition [ICPC‐2] or International Classification of Diseases 10th revision [ICD‐10]) during a 1‐year period in the Norwegian Prescription Database. Nine chronic diseases were examined: attention deficit/hyperactivity disorder, epilepsy, migraine, mental illness, cardiovascular disease, diabetes, autoimmune disorders, gastro‐oesophageal reflux disease (GORD), and allergy. Additionally, antibacterials recommended for respiratory tract infections and antivirals were examined (defined by Anatomical Therapeutic Chemical codes). Standardized morbidity ratios (SMR) for each disease were calculated.ResultsFifty‐nine percent of the population with asthma had at least one of nine chronic diseases examined, compared with 18% in the general population. Few individuals with asthma had more than one additional chronic disease (6% of male subjects and 8% of female subjects). SMRs were increased for all diseases except diabetes, implying higher than expected occurrence of the specific diseases in people with asthma. This pattern was observed in both age groups (8–19 and 20–29 years) and genders. Allergy and GORD had highest SMR (range 3.2–4.8), whereas the other diseases were in the range 1.2–2.5.ConclusionsAn excess occurrence of comorbidities was found in the population with asthma. A majority of people with asthma had one additional chronic disease, and few had more than one. Copyright © 2011 John Wiley & Sons, Ltd.
Measurement of polymer‐to‐polymer contact friction in thermoforming
Authors: Martin P.J. , McCool R. , Härter C. , Choo H.L. 
Published: September 2011

AbstractContact friction plays a critical role in all the major thermoforming processes for polymers. However, these effects are very difficult to measure in practice and, as a result, have received little scientific investigation. In this work, two independently developed test methods for the measurement of elevated temperature polymer‐to‐polymer contact friction are presented, and their results are compared in detail for the first time. One is based on a modified moving sled friction test, whereas the other uses a rotational rheometer. In each case, friction tests were conducted between two plug and two sheet materials. The results show that broadly similar coefficients of friction were obtained from the two test methods. The measured values were quite low (<0.3) at lower temperatures and typically were higher for polypropylene (PP) sheet than for polystyrene (PS). On approaching the glass transition temperature for PS (95°C) and the crystalline melting point for PP (165°C), the friction coefficients rose very sharply, and both test techniques became increasingly unreliable. It was concluded that despite their physical differences, both test techniques were able to capture the highly temperature sensitive nature of friction between polymer materials used in thermoforming. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Preparation of electrospun electroactive POMA fiber mats
Authors: Dai Chung‐Feng , Weng Chang‐Jian , Yeh Tzu‐Chun , Lai Bo‐Cheng , Sung Chang‐Yu , Wei Yen , Chang Kuan‐Chin , Yeh Jui‐Ming 
Published: September 2011

AbstractA neat electroactive freestanding non‐woven mat was first prepared from poly(o‐methoxyaniline) (POMA) using an electrospinning technique without blending or grafting. Results showed that a continuous fibre structure was obtained for high weight‐average molecular weight M̄w of POMA, i.e. POMA forced to become more soluble when synthesized in the presence of CaCl2 and an alkoxyl‐ring‐substituted structure. By performing gel permeation chromatography and viscosity tests, we found that M̄w ≈ 69 000 g mol−1 and concentrations were critical to the formation of beads or fibres. The electrospinning parameters that cause morphological changes were found by scanning electron microscopy. By comparing these with governing parameters such as viscosity, feeding rate, collector distance and applied voltage, uniform POMA fibres were produced from 5 wt% POMA solution at 20 kV with a feeding rate of 0.02 mL min−1 and nozzle‐to‐collector distance of 12 cm. In addition, the electroactivity and mechanical strength of the neat electrospun non‐woven mats were studied by electrochemical cyclic voltammogram and dynamic mechanical analysis, respectively. Copyright © 2011 Society of Chemical Industry
Impact of localized regions with very high series resistances on cell performance
Authors: Sugianto Adeline , Breitenstein Otwin , Tjahjono Budi S. , Lennon Alison , Mai Ly , Wenham Stuart R. 
Published: September 2011

ABSTRACTThe J–V curves recorded under illumination for solar cells having a high series resistance can appear shunted when a fraction of the cell area is affected by very high series resistance values. This “apparent shunting” behaviour was observed in n‐type rear‐junction, laser‐doped cells with light‐induced plated front contacts. Localized series resistance measurements of the affected cells by photoluminescence imaging revealed that over 20% of the cell area had a series resistance above 10 Ω cm2 and extending up to a maximum value of 168 Ω cm2. It was found that cells with localized series resistances have a detrimental impact on the FF and Jsc of the device. Furthermore, an unusual FF recovery was also observed with decreasing level of illumination. A solar cell model with localized high series resistances was developed to further study this “apparent shunting” behaviour with respect to its impact on cell performance. Copyright © 2011 John Wiley & Sons, Ltd.
Temperature dynamics of multijunction concentrator solar cells up to ultra‐high irradiance
Authors: Braun Avi , Hirsch Baruch , Vossier Alexis , Katz Eugene A. , Gordon Jeffrey M. 
Published: September 2011

ABSTRACTWe report experimental results for the effect of irradiance (from 12 up to 8600 suns) on the temperature coefficients of the key performance parameters of multijunction concentrator solar cells, with a flash‐like, real‐sun optical system. Particular attention is paid to the time scales and magnitudes of junction heating, hence the degree to which the cell can be deemed isothermal. The implications for corresponding measurements from solar simulators with pulsed artificial light and for the performance evaluation of concentrator photovoltaics are also addressed. Copyright © 2011 John Wiley & Sons, Ltd.
Lateral spectrum splitting concentrator photovoltaics: direct measurement of component and submodule efficiency
Authors: Wang Xiaoting , Waite Nick , Murcia Paola , Emery Keith , Steiner Myles , Kiamilev Fouad , Goossen Keith , Honsberg Christiana , Barnett Allen 
Published: September 2011

ABSTRACTTo achieve high energy conversion efficiency, a solar module architecture called lateral spectrum splitting concentrator photovoltaics (LSSCPV) is being developed. LSSCPV can concentrate available sunlight and laterally split a single beam into bands with different spectra for absorption by different solar cells with band gaps matched to the split spectrum. Test assemblies of a sample LSSCPV architecture were constructed, each of which contains four p–n junctions and two optical pieces. Independent experiments or simulations had been implemented on the components but by using optimal assumptions. In order to examine the actual performances of all the components, which are dependent on each other and the light source, direct outdoor measurements were made. A set of self‐consistent efficiency definitions was articulated and a test bed was developed to measure the parameters required by the efficiency calculation. By comparing the component efficiency items derived from the outdoor measurement and the expected values based on independent simulations, the potential opportunities for efficiency improvement are determined. In the outdoor measurement at the University of Delaware, the optical component demonstrated 89·1% efficiency. Additional assemblies were tested at the National Renewable Energy Laboratory. One assembly demonstrated 36·7% submodule efficiency, which compares favorably with the 32·6% previously reported verified submodule efficiency. Copyright © 2011 John Wiley & Sons, Ltd.
Influence of the Configuration of the Plasma Chamber on the Surface Modification of Synthetic Vulcanized Rubber Treated with Low‐pressure Oxygen RF Plasma
Authors: Torregrosa‐Coque Rafael , Martín‐Martínez José Miguel 
Published: September 2011

AbstractThree different configurations of RF low‐pressure oxygen plasmas were used to modify the surface of vulcanized styrene–butadiene rubber. Direct, etching and downstream oxygen plasma treatments of the rubber were carried out for length of treatment between 1 and 10 min. The oxygen plasma treated rubber surfaces were characterized by ethylene glycol contact angle measurements, ATR‐IR and XPS spectroscopy and scanning electron microscopy (SEM). Adhesion of the oxygen plasma treated rubber to polyurethane adhesive was carried out by means of T‐peel test and the loci of failure of the joints were characterized by means of ATR‐IR spectroscopy. Three different oxygen plasma configurations obtained by changing the position of the rubber sample in the plasma chamber and by changing the shelves (power, ground, floating) were used to modify the extent of surface modification and the temperature reached on rubber surface. The direct oxygen plasma was the most aggressive treatment and the secondary downstream plasma the less one. The increase in the length of the oxygen plasma treatment allowed the most efficient removal of antiozonant paraffin wax from the as‐received rubber. Furthermore, the oxygen plasma treatments created CO moieties on the rubber surface. On the other hand, only 1 min treatment time was sufficient to decrease noticeably the contact angle value on the rubber surface, irrespective of the oxygen plasma chamber configuration and the length of treatment. Oxygen plasma treatment caused surface oxidation and ablation on the rubber surface, as well as an increase of the temperature that also determined the extent of paraffin wax migration, the migration was favoured for temperature higher than 45 °C. Finally, the migration of paraffin wax was produced for at least 24 h after oxygen plasma treatment and poor adhesion to polyurethane adhesive was obtained, due to the creation of a weak boundary layer of paraffin wax at the rubber–polyurethane interface. The migration of paraffin wax caused during plasma treatment was the dominant factor in decreasing the adhesion of rubber to polyurethane adhesive.magnified image
Explosive Mixtures for Explosive Welding of Thin Foils: Part 2. RDX–Baking Soda Mixtures
Authors: Andreevskikh Leonid A. , Dendenkov Yury P. , Drennov Oleg B. , Mikhailov Anatoly L. , Titova Nadezhda N. , Deribas Andrey A. 
Published: September 2011

AbstractExplosive mixtures of RDX powder and baking soda have been investigated. It was found that the size of the RDX particles had crucial influence on the detonation properties of such explosives. The suggested mix of explosives can be recommended for use in explosive welding and some other applications.
Development of a Functional Assessment Scale for Ambulatory Boys with Duchenne Muscular Dystrophy
Authors: Scott Elaine , Eagle Michelle , Mayhew Anna , Freeman Jenny , Main Marion , Sheehan Jennie , Manzur Adnan , Muntoni Francesco ,   The North Star Clinical Network for Paediatric Neuromuscular Disease
Published: September 2011

AbstractBackground and PurposeThe aims of this study were to develop a clinical assessment scale to measure functional ability in ambulant boys with Duchenne muscular dystrophy and to determine the reliability of the scale in multiple centres in the UK.MethodsFocus groups and workshops were held with experienced paediatric neuromuscular physiotherapists to determine scale content. A manual was prepared with accompanying videos, and training sessions were conducted. A total of 17 physiotherapists from participating centres used the videos to determine inter‐rater reliability. Five determined the intra‐rater reliability.ResultsStrength of agreement for these groups based on total subject scores was very good (0.95 and ≥0.93 for consistency and absolute agreement, respectively). Test–retest ability was high, with perfect agreement between occasions for all but two items of the scale.ConclusionsOur study indicates that the North Star Ambulatory Assessment is practical and reliable. It takes only 10 minutes to perform and incorporates both universally used timed tests as well as levels of activities, which allow assessment of high‐functioning boys with Duchenne muscular dystrophy. Copyright © 2011 John Wiley & Sons, Ltd.
Evidence for the presence of proteolytically active secreted aspartic proteinase 1 of Candida parapsilosis in the cell wall
Authors: Vinterová Zuzana , Šanda Miloslav , Dostál Jiří , Hrušková‐Heidingsfeldová Olga , Pichová Iva 
Published: September 2011

AbstractPathogenic yeasts of the genus Candida produce secreted aspartic proteinases, which are known to enhance virulence. We focused on Sapp1p proteinase secreted by Candida parapsilosis and studied the final stage of its passage through the cell wall and release into the extracellular environment. We found that Sapp1p displays enzyme activity prior to secretion, and therefore, it is probably fully folded within the upper layer of the cell wall. The positioning of cell surface‐associated Sapp1p was detected by cell wall protein labeling using biotinylation agents, extraction of cell wall proteins by β‐mercaptoethanol, immunochemical detection, and mass spectrometry analysis. All lysine residues present in the structure of soluble, purified Sapp1p were labeled with biotin. In contrast, the accessibility of individual lysines in cell wall‐associated Sapp1p varied with the exception of four lysine residues that were biotinylated in all experiments performed, suggesting that Sapp1p has a preferred orientation in the cell wall. As the molecular weight of this partially labeled Sapp1p did not differ among the experiments, we can assume that the retaining of Sapp1p in the cell wall is not a totally random process and that pathogenic yeasts might use this cell‐associated proteinase activity to enhance degradation of appropriate substrates.
STITCHER: Dynamic assembly of likely amyloid and prion β‐structures from secondary structure predictions
Authors: Bryan Allen W. , O'Donnell Charles W. , Menke Matthew , Cowen Lenore J. , Lindquist Susan , Berger Bonnie 
Published: September 2011

AbstractThe supersecondary structure of amyloids and prions, proteins of intense clinical and biological interest, are difficult to determine by standard experimental or computational means. In addition, significant conformational heterogeneity is known or suspected to exist in many amyloid fibrils. Previous work has demonstrated that probability‐based prediction of discrete β‐strand pairs can offer insight into these structures. Here, we devise a system of energetic rules that can be used to dynamically assemble these discrete β‐strand pairs into complete amyloid β‐structures. The STITCHER algorithm progressively ‘stitches’ strand‐pairs into full β‐sheets based on a novel free‐energy model, incorporating experimentally observed amino‐acid side‐chain stacking contributions, entropic estimates, and steric restrictions for amyloidal parallel β‐sheet construction. A dynamic program computes the top 50 structures and returns both the highest scoring structure and a consensus structure taken by polling this list for common discrete elements. Putative structural heterogeneity can be inferred from sequence regions that compose poorly. Predictions show agreement with experimental models of Alzheimer's amyloid beta peptide and the Podospora anserina Het‐s prion. Predictions of the HET‐s homolog HET‐S also reflect experimental observations of poor amyloid formation. We put forward predicted structures for the yeast prion Sup35, suggesting N‐terminal structural stability enabled by tyrosine ladders, and C‐terminal heterogeneity. Predictions for the Rnq1 prion and alpha‐synuclein are also given, identifying a similar mix of homogenous and heterogeneous secondary structure elements. STITCHER provides novel insight into the energetic basis of amyloid structure, provides accurate structure predictions, and can help guide future experimental studies. Proteins 2012. © 2011 Wiley Periodicals, Inc.