bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collision‐induced dissociation of synthetic polymers containing hydride groups: the case of poly(methylhydrosiloxane) homopolymers and poly(methylhydrosiloxane)‐co‐(dimethylsiloxane) copolymers
Authors: Fouquet Thierry , Chendo Christophe , Toniazzo Valérie , Ruch David , Charles Laurence 
Published: December 2012

RATIONALEWhen substituting one methyl moiety by a hydrogen atom in each end‐group of a trimethylsilyl‐terminated poly(dimethylsiloxane) (PDMS), dissociation reactions of oligomers adducted with ammonium were observed to proceed at a much higher rate, evidencing the high reactivity of hydride groups. Polymeric molecules containing methylhydrosiloxane (MHS) units could thus be expected to exhibit a different tandem mass spectrometric (MS/MS) behavior from PDMS.METHODSTrimethylsilyl‐terminated PMHS and trimethylsilyl‐terminated poly(MHS)‐co‐(DMS) were electrosprayed in the gas phase either as ammonium adducts or lithium adducts. Product ions generated upon collision‐induced dissociation (CID) were accurately mass measured in an orthogonal acceleration time‐of‐flight mass analyzer.RESULTSIn contrast to PDMS adducted with lithium, useful structural features could be obtained from product ions generated upon CID of lithium adducts of PMHS. The presence of multiple hydride groups in PMHS induced numerous rearrangements when activating ammonium adducts of these oligomers. MS/MS reactions observed for cationic adducts of MHS‐DMS co‐oligomers were clearly a combination of major dissociation routes established for the corresponding homopolymers. However, the concerted loss of H2 and ammonia typically observed from ammonium adducts of PMHS was always shown to generate a quite abundant product ion even from co‐oligomers enriched with DMS units.CONCLUSIONSThe high reactivity of hydride moieties, previously evidenced when these groups were at the end of PDMS chains, is also at work in PMHS, where each monomer contains a Si‐H function. The presence of these hydride groups would increase the nucleophilic character of the oxygen atoms, favoring a tight bonding of lithium, and hence allowing in‐chain cleavages to occur. In PMHS ammonium adducts, the particular reactivity of hydride moieties was illustrated by multiple hydride transfers but also by a dehydrogenation reaction systematically observed to proceed, together with the loss of ammonia, from all precursor ions. This latter reaction remained a very competitive process even from MHS/DMS co‐oligomers with a low relative number of MHS units. Copyright © 2012 John Wiley & Sons, Ltd.
Evaluation of electron ionization cross‐sections of methyl halides
Authors: Kumar Rajeev , Pal Satyendra 
Published: December 2012

RATIONALEElectron collision with methyl halides CH3X (X = F, Cl, Br) plays an important role in various atmospheric and plasma modelling processes. The gaseous methyl halides are harmful to the troposphere and the stratospheric ozone layer. Knowledge of the ionization cross sections and ionization rate coefficients of the free gaseous halides is therefore desirable in the study of these processes.METHODSThe partial single and double differential cross‐sections with the integral ionization cross‐sections of the gaseous halides by electron collision were calculated using a modified Jain‐Khare semi‐empirical approach. The ionization rate coefficients corresponding to partial ionization cross‐sections were calculated by the Maxwell‐Boltzmann distribution of energy.RESULTSThe Jain‐Khare formalism has different approaches for the evaluation of single differential, double differential and integral ionization cross‐sections. The partial single differential cross‐sections as a function of energy loss (sum of ionization threshold and the secondary electron energy) suffered by the incident electron were calculated at incident electron energies of 100 and 200 eV. The double differential cross‐sections were computed at the same electron energies and scattering angles of 30° and 60°. The behavior of double differential cross‐sections with scattering angles from 0° to 180° at constant secondary electron energies of 10 and 20 eV and fixed primary electron energies 100 and 200 eV was also calculated. The partial and total (sum of all partial cross‐sections) integral ionization cross‐sections were evaluated from the ionization threshold to 1000 eV.CONCLUSIONSThe applied formalism is useful for the calculation of partial and total integral/or differential cross‐sections at low energies. The integral ionization cross‐sections showed good agreement with available experimental/or theoretical data. The data obtained for these compounds were not previously available, so the results will be of value to the experimental and theoretical community concerned with plasma and atmospheric processes. Copyright © 2012 John Wiley & Sons, Ltd.
Analysis of the biochemical role of Lys‐11 in polyubiquitin chain formation using quantitative mass spectrometry
Authors: Jung Jin Woo , Bae Sung Jun , Kang Gum‐Yong , Kim Kyun‐Hwan , Yeo Woon‐Seok , Park Sang‐Hyun , Seol Jae Hong , Yi Eugene C. , Kim Kwang Pyo 
Published: December 2012

RATIONALEProtein ubiquitination plays a critical role in regulating many cellular events, such as protein localization and stability, cellular signal transduction and DNA repair. Recent studies have shown that polyubiquitin (polyUb) chains elongate through heterogeneous isopeptide linkages to K11, K29, K48 and K63. In this study we have investigated the usage of isopeptide linkages of polyUb chains in different molecular weight regions by using quantitative mass spectrometry.METHODSRecombinant Chfr protein was autoubiquitinated by E1 enzyme, E2 enzyme UbcH5 and ubiquitin (WT Ub, K11R Ub, K48R Ub and K63R Ub) in vitro, and different molecular weight regions of ubiquitinated Chfr were then subjected to liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) following sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS‐PAGE) and in‐gel digestion.RESULTSAbsolute QUantitative Analysis (AQUA) of polyUb chain formation with wild‐type (WT) and point mutants of ubiquitin was performed, and the results suggested that the K11 polyUb chain was most frequently used in the high ubiquitin conjugates of WT Ub. Furthermore, the extent of polyUb chain formation with K11R Ub was decreased about 10‐fold compared to polyUb chain formation with WT Ub through the entire molecular weight region. The present study suggests that the linkage through K11 plays crucial roles in polyUb chain formation.CONCLUSIONSTopologies of polyUb chains in the low and high Ub conjugates were studied using mass spectrometry. K48 and K63 were the primary ubiquitination sites of the low molecular weight Ub conjugates, whereas K11 was the critical site of polyUb chain formation in high molecular weight Ub conjugates. Copyright © 2012 John Wiley & Sons, Ltd.
Semi‐quantitative analysis of contaminants in soils by direct analysis in real time (DART) mass spectrometry
Authors: Grange Andrew H. 
Published: December 2012

RATIONALECleaning up contaminated sites is a goal of the U.S. Environmental Protection Agency (EPA). A simple, high‐throughput, inexpensive, selective, and specific screening method for semi‐volatile, polar organic contaminants would provide high spatial resolution for monitoring remediation and for documenting successful clean ups in numerous Superfund, Brownfield, and other contaminated sites.METHODSAn autosampler/Direct Analysis in Real Time (DART)/time‐of‐flight (TOF) mass spectrometer, with or without a Vapur® evacuated flange, was used to analyze 0.01–33% levels of aspirin, diphenylamine, and pentachlorophenol mixed with soil. Triplicate water‐soaked swabs were manually rotated in wet analyte:soil mixtures, air dried for 2–3 h, and analyzed directly. To minimize carryover, insensitive and sensitive instrumental conditions were used to analyze high and low analyte levels, respectively. Simulated two‐dimensional (2D) mapping and remediation threshold experiments were performed to test the utility of DART‐TOFMS for possible sampling strategies.RESULTSAnalyte levels differing by factors of 10 were discernible. Data were acquired for 30 swabs in 0.9 min and 3 min with helium stream temperatures of 150 °C and 250 °C and swab transport velocities of 1.45 cm/s and 0.5 cm/s, respectively. With the Vapur flange attached, the average relative standard deviations (RSDs) (n = 3) were between 16% and 40% for different analytes and analyte levels. Carryover was greatly reduced by removing the Vapur flange, but higher RSDs and occasional plugging of the cone orifice were observed.CONCLUSIONSA rapid, simple, rugged, and relatively inexpensive, but selective and sufficiently sensitive, semi‐quantitative screening method for semi‐volatile, polar, organic compounds in soil was demonstrated. The technique would provide the high spatial resolution necessary to find localized areas of high contamination within contaminated sites that might pose a risk to human and ecological health. Published 2012. This article is a US Government work and is in the public domain in the USA.
Tightly coupled ultrashort baseline and inertial navigation system for underwater vehicles: An experimental validation
Authors: Morgado M. , Oliveira P. , Silvestre C. 
Published: December 2012

AbstractThis paper presents a new ultrashort baseline (USBL) tightly coupled integration technique to enhance error estimation in low‐cost strapdown inertial navigation systems (INSs), with application to underwater vehicles. In the proposed strategy, the acoustic array spatial information is directly exploited in an extended Kalman filter (EKF) implemented in a direct feedback structure. Instead of using the USBL position fixes or computed range and elevation/bearing angles to correct the INS error drifts, as in classical loosely coupled strategies, the novel tightly coupled strategy directly embeds in the EKF the round‐trip‐time and time‐difference‐of‐arrival of the acoustic signals arriving at the onboard receivers. The enhanced performance of the proposed filtering technique is evidenced both through extensive numerical simulations and with experimental data obtained in field tests at sea. The tightly coupled filter is also shown to be able to operate closer to theoretical performance lower bounds, such as the posterior Cramér‐Rao lower bound, using Monte‐Carlo simulations. This paper details the design and description of an USBL/INS prototype to be used as a low‐cost navigation system, including the acoustic processing and positioning system, fully developed in‐house. The developed system validates the usage of the proposed technique with real data in real world operation scenarios, and its enhanced performance compared to classical strategies is evaluated experimentally (median improvement level of 15% in typical operating conditions). Improved and faster convergence to nominal trajectories from multiple initial conditions, as well as enhanced accelerometer and rate gyros estimation capabilities, are also demonstrated experimentally for the new tightly coupled filter.
Chaotic modulation‐based spread spectrum communication using complex dynamics of chaotic DC–DC current mode controlled boost converter
Authors: Thukral Manish Kumar , Sherpa Karma Sonam 
Published: December 2012

ABSTRACTAmple amount of research has been done for analysing nonlinear phenomenon in power electronics converters. Application of chaotic power electronics converters in spread spectrum communication in recent times is catching interest. This paper proposes a methodology for using chaotic current mode‐controlled DC (Direct Current)–DC (Direct Current) boost converter in spread spectrum communication. A noncoherent receiver is developed. For this, an Adaline‐based adaptive filter is designed to recover the message from spread spectrum signal at the receiver end. The proposed Adaline‐based receiver is tested by transmitting various types of message signals while considering white noise at different signal‐to‐noise ratio. For designing noncoherent receiver‐based chaotic communication, use of power electronics converters is expected to play a vital role in the future. Copyright © 2012 John Wiley & Sons, Ltd.
Improving QoS and security in wireless ad hoc networks by mitigating the impact of selfish behaviors: a game‐theoretic approach
Authors: Szott Szymon , Natkaniec Marek , Pach Andrzej R. 
Published: December 2012

ABSTRACTSelfish users are known to be a severe security threat for wireless ad hoc networks. In particular, they can exploit mechanisms designed to assure quality of service (QoS) in the network. In this paper, the problem of backoff misbehavior in IEEE 802.11 enhanced distributed channel access (EDCA) networks is studied using a game‐theoretic approach. First, it is shown how this selfish behavior can disrupt traffic differentiation. Then, a solution is proposed, which encourages standard‐compliant behavior and thus proper QoS provisioning. This solution is based on punishing selfish nodes by degrading their throughput proportionally to the degree of misbehavior. A practical application of the solution is proposed, which is verified through simulations. Results show that the suggested mechanism considerably improves QoS provisioning in IEEE 802.11 EDCA ad hoc networks in the presence of selfish nodes. Furthermore, it is shown that the mechanism is adaptive, does not have a negative impact on the throughput of well‐behaving nodes, and provides legacy node support. Copyright © 2012 John Wiley & Sons, Ltd.
Spatial moving average risk smoothing
Authors: Botella‐Rocamora P. , López‐Quílez A. , Martinez‐Beneito M. A. 
Published: December 2012

This paper introduces spatial moving average risk smoothing (SMARS) as a new way of carrying out disease mapping. This proposal applies the moving average ideas of time series theory to the spatial domain, making use of a spatial moving average process of unknown order to define dependence on the risk of a disease occurring. Correlation of the risks for different locations will be a function of m values (m being unknown), providing a rich class of correlation functions that may be reproduced by SMARS. Moreover, the distance (in terms of neighborhoods) that should be covered for two units to be found to make the correlation of their risks 0 is a quantity to be fitted by the model. This way, we reproduce patterns that range from spatially independent to long‐range spatially dependent.We will also show a theoretical study of the correlation structure induced by SMARS, illustrating the wide variety of correlation functions that this proposal is able to reproduce. We will also present three applications of SMARS to both simulated and real datasets. These applications will show SMARS to be a competitive disease mapping model when compared with alternative proposals that have already appeared in the literature. Finally, the application of SMARS to the study of mortality for 21 causes of death in the Comunitat Valenciana will allow us to identify some qualitative differences in the patterns of those diseases. Copyright © 2012 John Wiley & Sons, Ltd.
Reduction of Free Fatty Acids in Acidic Nonedible Oils by Modified K10 Clay
Authors: Pires João , Brasil Beatriz , Araújo M. Eduarda M. 
Published: December 2012

AbstractBiodiesel is a biofuel obtained from vegetable oils. The oils used as raw materials are usually refined edible vegetable oils. Nonedible acidic oils are unsuitable for biodiesel production unless reduction of the high content in free fatty acids (FFA) of these materials had been achieved. Obtaining a good raw material from unprofitable oils becomes an important research field. Additionally clays have a long history in industrial sorption and catalysis, some being commercially available and with properties that can be modified. In this work we present the results of the use of the montmorillonite clay K10 and two acid modified clays K10(I) and K10(II), in the esterification of stearic acid with methanol and 95 % of methyl stearate was obtained with K10(II). These clays were then used for the first time to reduce the acidity of enhanced FFA sunflower oil and they show to be very effective. Reduction of FFA from 11 to 4 % was obtained with K10(II) mainly due to 94 % conversion of FFA into fatty acid methyl esters (FAME). These clays were also tested with two waste oils, one from domestic use and the other gathered from different restaurants, and showed their ability to lower the acidity of these oils. Reactions were followed by 1H NMR as well as quantitative determination of FFA and FAME. Clays were characterized by FTIR and XRD.
Antioxidant enzymes in cerebral cortex of immature rats following experimentally‐induced seizures: upregulation of mitochondrial MnSOD (SOD2)
Authors: Folbergrová Jaroslava , Ješina Pavel , Nůsková Hana , Houštěk Josef 
Published: December 2012

AbstractWe have recently demonstrated the evidence of oxidative stress in brain of immature rats during seizures induced by dl‐homocysteic acid (dl‐HCA). The aim of the present study was to investigate the antioxidant defense mechanisms under these conditions. Seizures were induced in immature 12‐day‐old rats by bilateral icv infusion of dl‐HCA (600 nmol/side), and the activities of the main antioxidant enzymes were examined in supernatants of the cerebral cortex during the acute phase of seizures and at several periods of survival, up to 5 weeks, following these seizures. In control animals individual antioxidant enzymes revealed different changes during the studied postnatal period (PD 12 till PD 47). Total superoxide dismutase (SOD), CuZn SOD (SOD1), Mn SOD (SOD2) and glutathione peroxidase (GPX) activities were increasing while, catalase activity decreased and the activity of glutathione reductase (GR) remained unchanged. In HCA‐treated animals, the activity of total SOD, SOD1 and particularly SOD2 significantly increased at 20 h and 6 days of survival. Importantly, upregulation of SOD2 was also confirmed in mitochondria at the protein level by immunoblotting. The activities of other antioxidant enzymes including catalase and GPX did not significantly differ upon HCA treatment from the appropriate controls at any of the studied time intervals. The pronounced and selective upregulation of SOD2 points to enhanced ROS levels in the mitochondrial matrix. This may be associated with inhibition of respiratory chain complex I that we have demonstrated in our previous studies. The present findings suggest that oxidative stress occurring in the brain of immature rats during and following the seizures induced by dl‐HCA is apparently due to both the increased free radical production and the limited antioxidant defense.
Operational risk assessments by supply chain professionals: Process and performance
Authors: Tazelaar Frits , Snijders Chris 
Published: December 2012

AbstractWe consider the “process‐performance paradox” in the assessment of operational risks by professionals in the field of operations and supply chain management (OSCM). The paradox states that although professionals with more expertise tend to decide in different ways, they often do not make better assessments than those with less expertise. We first replicate that this paradox exists in a context of the assessment of operational supply risks, and then show how the paradox can be understood as the consequence of process characteristics mediating the relation between expertise and assessment performance.Using an experimental setup, we had 234 OSCM‐professionals assess the operational risk in two series of different business cases, and measured several characteristics of their decision‐making process. The strength of our approach lies in the fact that the business cases were real‐life cases from our database of purchasing transactions in the area of IT‐purchasing. This allows a comparison of the risk assessments of the professionals with the actual supply risk as was known from the survey database. Our findings show that, contrary to what is often assumed, the OSCM‐professionals with more expertise do not use less information while assessing, nor are they faster. Instead, our results show that specialized expertise goes with increased certainty about the assessments, and general expertise goes with an increased use of intuitive judgment. However, the net effects of these expertise characteristics on assessment performance are zero. In the case of specialized expertise this is because specialized expertise is itself negatively related to performance. In the case of general expertise this is because the net effects of the use of intuition on performance are zero.
High resolution trilobite stratigraphy of the Lower–Middle Ordovician Öland Series of Baltoscandia
Authors: PÄRNASTE HELJE , BERGSTRÖM JAN , ZHIYI ZHOU 
Published: December 2012

AbstractThe first ever list of the regional Öland Series (Tremadocian to mid Darriwilian) trilobites and agnostids from the whole of Baltoscandia is compiled. The study includes revision of systematics as well as vertical and horizontal distribution. This is necessary because of the uneven state of knowledge, some faunas having being studied recently, others not for more than a century. Three successive faunal types are recognized: the Olenid Fauna surviving from the Cambrian in black bituminous shale facies, the immigratingCeratopygeFauna, and the stabilized Asaphid Fauna. The latter fauna collapsed in the middle of Darriwilian and gave way to a set of new post-Ölandian faunas.
INFLUENCE OF FAMILY STRUCTURE ON CHILD HEALTH: EVIDENCE FROM INDIA
Authors: KUMAR ABHISHEK , RAM FAUJDAR 
Published: December 2012

SummaryThis paper examines the association between family structure and child health in India using the third round of the National Family Health Survey, conducted during 2005–06. Two important child health indicators – underweight and full immunization – are used as dependent variables. Descriptive and multivariate statistics are deployed to establish the relationship between family structure and child health. The results of the descriptive statistics show that children who belong to a non-nuclear family have better nutritional status and higher immunization coverage than those in nuclear families. Children living with siblings have worse health status than those living without siblings for both the outcomes. Multivariate analysis shows that family structure has a small effect on the two child health outcomes, which is no longer significant after adjusting for socioeconomic measures and region. However, number of siblings is significantly and negatively associated with the nutritional status of children and full immunization coverage, even after other socio-demographic and geographic factors are controlled for. Along with family structure, parent's educational attainment, age of the mother and household economic status are significant determinants of underweight and full immunization.