bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ab initio chemical kinetics for the NH2 + HNOx reactions, part II: Kinetics and mechanism for NH2 + HONO
Authors: Xu Shucheng , Lin M. C. 
Published: September 2009

AbstractThe kinetics and mechanism for the reaction of NH2 with HONO have been investigated by ab initio calculations with rate constant prediction. The potential energy surface of this reaction has been computed by single‐point calculations at the CCSD(T)/6‐311+G(3df, 2p) level based on geometries optimized at the CCSD/6‐311++G(d, p) level. The reaction producing the primary products, NH3 + NO2, takes place via precomplexes, H2N⋅⋅⋅c‐HONO or H2N⋅⋅⋅t‐HONO with binding energies, 5.0 or 5.9 kcal/mol, respectively. The rate constants for the major reaction channels in the temperature range of 300–3000 K are predicted by variational transition state theory or Rice–Ramsperger–Kassel–Marcus theory depending on the mechanism involved. The total rate constant can be represented by ktotal = 1.69 × 10−20 × T2.34 exp(1612/T) cm3 molecule−1 s−1 at T = 300–650 K and 8.04 × 10−22 × T3.36 exp(2303/T) cm3 molecule−1 s−1 at T = 650–3000 K. The branching ratios of the major channels are predicted: k1 + k3 producing NH3 + NO2 accounts for 1.00–0.98 in the temperature range 300–3000 K and k2 producing OH + H2NNO accounts for 0.02 at T > 2500 K. The predicted rate constant for the reverse reaction, NH3 + NO2 → NH2 + HONO represented by 8.00 × 10−26 × T4.25 exp(−11,560/T) cm3 molecule−1 s−1, is in good agreement with the experimental data. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 678–688, 2009
Competitive binding exchange between alkali metal ions (K+, Rb+, and Cs+) and Na+ ions bound to the dimeric quadruplex [d(G4T4G4)]2: a 23Na and 1H NMR study
Authors: Cesare Marincola Flaminia , Virno Ada , Randazzo Antonio , Mocci Francesca , Saba Giuseppe , Lai Adolfo 
Published: September 2009

AbstractA comparative study of the competitive cation exchange between the alkali metal ions K+, Rb+, and Cs+ and the Na+ ions bound to the dimeric quadruplex [d(G4T4G4)]2 was performed in aqueous solution by a combined use of the 23Na and 1H NMR spectroscopy. The titration data confirm the different binding affinities of these ions for the G‐quadruplex and, in particular, major differences in the behavior of Cs+ as compared to the other ions were found. Accordingly, Cs+ competes with Na+ only for the binding sites at the quadruplex surface (primarily phosphate groups), while K+ and Rb+ are also able to replace sodium ions located inside the quadruplex. Furthermore, the 1H NMR results relative to the CsCl titration evidence a close approach of Cs+ ions to the phosphate groups in the narrow groove of [d(G4T4G4)]2. Based on a three‐site exchange model, the 23Na NMR relaxation data lead to an estimate of the relative binding affinity of Cs+ versus Na+ for the quadruplex surface of 0.5 at 298 K. Comparing this value to those reported in the literature for the surface of the G‐quadruplex formed by 5′‐guanosinemonophosphate and for the surface of double‐helical DNA suggests that topology factors may have an important influence on the cation affinity for the phosphate groups on DNA. Copyright © 2009 John Wiley & Sons, Ltd.
Constant time gradient HSQC–iDOSY: practical aspects
Authors: McLachlan A. S. , Richards J. J. , Bilia A. R. , Morris G. A. 
Published: September 2009

AbstractAn improved constant time gradient HSQC–iDOSY pulse sequence is presented, and the corresponding form of the Stejskal–Tanner equation is derived. The pulse sequence is particularly well suited to the problem of analysing mixtures of chemically cognate species, where the high spectral resolution afforded by 1H13C correlation methods is needed for DOSY experiments to give good diffusion resolution. Its use is illustrated for a mixture of rutin and its aglycone quercetin. Copyright © 2009 John Wiley & Sons, Ltd.
Factors associated with a continuous regular analgesic use—a population‐based study of more than 45 000 Danish women and men 18–45 years of age
Authors: Hargreave Marie , Andersen Tina Veje , Nielsen Ann , Munk Christian , Liaw Kai‐Li , Kjaer Susanne K. 
Published: September 2009

AbstractPurposeWidespread use of and serious adverse effects associated with use of analgesics accentuates the need to consider factors related to analgesic use. The objective of this study was to describe continuous regular analgesics use and examine factors associated with a continuous regular analgesic use.MethodsThe study was based on data from two surveys and included a random sample of women and men aged 18–45 years from the general Danish population. Information on analgesics use, self‐rated health, demographic and lifestyle factors was collected using a self‐administered questionnaire. A total of 28 000 women and 33 000 men were invited to participate and 22 199 women (response‐rate 81.4%) and 23 080 men (response‐rate 71.0%), respectively, were included in the study. Data were analyzed using multivariate logistic regression.ResultsWe found that 27% of the women and 18% of the men reported a regular monthly use of at least seven analgesic tablets during the last year (continuous regular analgesics use). Besides poor self‐rated health we found in both sexes that increasing age, poor self‐rated fitness, and smoking were related to a continuous regular analgesics use. Nulliparity, low level of education, overweight/obesity, binge drinking, and abstinence were associated with a continuous regular analgesics use for women, while underweight and marital/cohabiting status were associated with a continuous regular analgesics use only for men.ConclusionsRegular monthly analgesic use during the last year was generally prevalent. Besides self‐rated health, several socio‐demographic and lifestyle factors were associated with a continuous regular analgesic use, although with some gender differences. Copyright © 2009 John Wiley & Sons, Ltd.
Polymeric nanofibers via flat spinneret electrospinning
Authors: Zhou Feng‐Lei , Gong Rong‐Hua , Porat Isaac 
Published: September 2009

AbstractElectrospun nanofibers are most often produced by needle electrospinning process, which has inherent disadvantages like clogging and low efficiency. In this study, an alternative needleless electrospinning process is reported for the fabrication of nanofibers based on a novel spinneret. Firstly, a spinneret with a 0.5‐mm diameter hole in the middle of a flat plastic cap was custom‐made that may be readily scaled up for mass production. Then, polyethylene oxide (PEO) aqueous solution with 6.0 wt% concentration was used to demonstrate the needleless electrospinning process. The processing window for the jet formation in the flat spinneret electrospinning process was determined. The relationships between various processing parameters (applied voltage, working distance, and flow rate) and the resultant PEO nanofibers were also investigated. It was found that stable fluid jet launched from the tip of the coned droplet anchored at the rim of the hole and formed fibers. The morphology and diameter of electrospun fibers were examined using scanning electron microscopy. The results show that PEO nanofibers produced by this needleless electrospinning have similar structure and morphology to those from the single needle source. Finally, the hole number of spinneret was increased to four holes, which was still able to produce smooth nanofibers with a higher production rate. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Study on a novel ion‐conductive compound plasticizer for soft and antistatic PVC materials
Authors: Wang Jiliang , Yang Wanqing , Lei Jingxin 
Published: September 2009

AbstractIon‐conductive plasticizers (ICP) composed of dibutyl phthalate (DBP) and butyl 2‐poly(ethylene glycol) phthalate (BPEGP)/lithium bisoxalato borate (LiBOB) were successfully synthesized. The composites blended of poly(vinyl chloride) (PVC) and ICP were fabricated in a Haake torque rheometer. FTIR, surface resistivity measurement, and mechanical test were used to investigate the comprehensive properties of the PVC/ICP composites. The results show that all the synthesized ICP can reduce the surface resistivity of the PVC/ICP composites to 105 Ω sq−1 orders of magnitude as the content of ICP reaches 50 phr. The increasing temperature enhances both the mobility of PEG molecular chains and the diffusion of lithium cations, and thus effectively improves the antistatic ability of the PVC/ICP compounds. With two exceptions of PVC/ICP compounds which include those made of PEG800 and PEG1000, the temperature dependence of the surface resistivity of PVC/ICP does not obey the Arrhenius relationship. The introduction of ICP into PVC matrix would improve the antistatic ability of the composites remarkably. Meanwhile, the mechanical properties of the composites are reduced to some reasonable extent. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Cure kinetics modeling and cure shrinkage behavior of a thermosetting composite
Authors: Ersoy Nuri , Tugutlu Mehmet 
Published: September 2009

AbstractIn this work, the cure kinetics and through‐the‐thickness cure shrinkage upon curing of a carbon fiber‐epoxy composite (AS4/8552) were studied. The study is composed of two major parts. Firstly, dynamic and isothermal Differential Scanning Calorimeter (DSC) scans were performed to develop a new cure kinetics model. The most appropriate kinetic model that produces a nearly perfect fit of all data sets corresponds to a process with two single‐step parallel autocatalytic reactions with diffusion control. Multivariate kinetic analysis was used to evaluate the parameters. In the second part of the study, the coefficients of thermal expansion (CTEs), the glass transition temperatures (Tg), and the through‐the‐thickness cure shrinkage strain values of the partially cured unidirectional and cross‐ply composite samples were measured by using a dynamic mechanical analyzer (DMA). Cure strains were measured throughout the Manufacturer's Recommended Cure Cycle (MRCC) with the same method. Results indicate that glass transition temperatures of partially cured samples can be measured very closely by the two methods (DSC and DMA). The methods proposed were proved to be very reliable to predict the degree of cure and to measure the through‐the‐thickness strains during the cure cycle. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Influence of carbon nanofiber structure on properties of linear low density polyethylene composites
Authors: Lee Sungho , Kim Myung‐Soo , Ogale Amod A. 
Published: September 2009

AbstractThree types of carbon nanofibers (MJ, Pyrograf®III PR‐19 and PR‐24) were incorporated into linear low density polyethylene (LLDPE) using intensive mixing. The electrical volume resistivity of composites decreased with the addition of CNFs from over 1012 Ω cm for pure LLDPE to less than 104 Ω cm for carbon nanofibers (CNF) contents of 15 wt% or more. Tensile modulus increased from 110 MPa for pure LLDPE to 200 MPa and 300 MPa for 15 wt% MJ and 15 wt% PR composites, respectively. However, the tensile strength remained fairly unchanged at about 20 MPa. Strain‐to‐failure decreased from 690% for pure LLDPE to 460% and 120% for 15 wt% MJ and 15 wt% PR composites, respectively. It was inferred that the interfacial interactions of LLDPE matrix with MJ fibers is better than that with PR fibers, resulting from the rougher surface of MJ fibers. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Synthesis of N‐alkoxybenzimidoyl azides and their reactions in electrophilic media
Authors: Dolliver Debra D. , Sommerfeld Thomas , Lanier Megan L. , Dinser Jordan A. , Rucker Richard P. , Weber Rebecca J. , McKim Artie S. 
Published: September 2009

AbstractA new general route to N‐alkoxybenzimidoyl azides [ArC(N3)=NOR] from a reaction of N‐alkoxybenzimidoyl bromide [ArC(Br)=NOR] with sodium azide in DMSO is described. These reactions result in the Z‐geometric configuration. These compounds show a moderate degree of thermal stability as assessed by differential scanning calorimetry, and lack reactivity in traditional 1,3‐dipolar cycloaddition ‘click’ reactions. Upon exposure to electrophilic compounds (trifluoroacetic acid or acetyl chloride), these azide compounds can react by two pathways: a Schmidt‐type rearrangement to form an N‐alkoxyurea or an isomerization–cyclization reaction pathway to form an N‐alkoxytetrazole. The route of the reaction has no dependence on solvent polarity and appears to depend upon the electrophile (H+ vs. CH3CO+): reaction of the azide with trifluoroacetic acid results predominantly in the urea; reaction with acetyl chloride results solely in the tetrazole. Calculations indicate that the urea product is thermodynamically favored over the tetrazole product. They also indicate that both reaction conditions result in an equilibration between the starting azide and the tetrazole with the tetrazole being the major component in this equilibrium mixture. The fact that the azide also undergoes a Schmidt‐type rearrangement to form an N‐alkoxyurea when treated with trifluoroacetic acid appears to indicate that the barrier for aromatic ring migration is lower in the protonated azide produced on reaction with trifluoroacetic acid than in the acetylated azide produced on reaction with acetyl chloride. Copyright © 2009 John Wiley & Sons, Ltd.
Magnetic‐Field Induced Strains in Ferromagnetic Shape Memory Alloy Ni55Mn23Ga22Deposited by RF‐Magnetron Sputtering
Authors: Bernard Florent , Rousselot Christophe , Delobelle Patrick , Hirsinger Laurent , Burdet Pierre 
Published: September 2009

Abstract1.5 µm–Ni55Mn23Ga22ferromagnetic thin films were deposited onto silicon substrates and silicon single beam cantilever using radio‐frequency magnetron sputtering. As‐deposited sample and heat‐treated thin films were studied on their silicon substrates and peeled off to determine the influence of the stress. Post‐heat treatment process allows at the films to achieve the shape memory effect (SME). Vibrating sample magnetometer (VSM) and deflection measurement of the sample annealed at 873 K during 36 ks exhibit ferromagnetic martensitic structure with a typical SME response to the magnetic field induced strains which match the values of the bulk material.
Differential efficacy of three commonly used pyrethroids against laboratory and field‐collected larvae and adults of Helicoverpa zea (Lepidoptera: Noctuidae) and significance for pyrethroid resistance management
Authors: Hopkins Bradley W , Pietrantonio Patricia V 
Published: September 2009

AbstractBACKGROUND: Helicoverpa zea (Boddie) pyrethroid resistance monitoring programs typically utilize cypermethrin in the adult vial test. Here we investigated if differences in insect growth stage and pyrethroid structure affect resistance ratios and discuss implications for pyrethroid resistance management.RESULTS: Vial bioassays with cypermethrin, esfenvalerate and bifenthrin were conducted on H. zea third instars and male moths from a susceptible laboratory colony and the F1 generation of a pyrethroid‐resistant field population. In the susceptible population, both growth stages were most sensitive to bifenthrin and adults were more sensitive to esfenvalerate than cypermethrin. LC50 resistance ratios for the larvae and adults of the resistant population were approximately two times higher for bifenthrin than cypermethrin or esfenvalerate.CONCLUSION: For the resistant population, vial assays using either growth stage gave similar resistance ratios for each of the three pyrethroids, respectively, proving the adult vial test accurately reflects larval resistance. However, as resistance ratios varied considerably depending on the pyrethroid used, resistance ratio values obtained with one pyrethroid may not be predictive of resistance ratios for other pyrethroids. Our results suggest that carefully chosen pyrethroid structures diagnostic for specific mechanisms of resistance could improve regional monitoring programs. Copyright © 2009 Society of Chemical Industry
A lightweight secure data transmission protocol for resource constrained devices
Authors: Yu Qian , Zhang Chang N. 
Published: September 2009

AbstractIn this paper we present a lightweight but robust security protocol based on the forward and backward property of RC4 stream cipher. The proposed protocol offers data confidentiality, data authentication, data integrity, and data freshness with less operation and low overhead. Also, it allows data packets to be received in any arbitrary order and achieves semantic security. Furthermore, it eliminates the requirement of frequent key renewal to overcome a special limitation of the stream ciphers. Due to the competitive efficiency and lightweight, the proposed protocol is considerable to provide secure data transmission among resource constrained devices, where the communication nodes have limited power resources and computational capabilities. This protocol not only applies to one‐to‐one communications, but also works for the broadcasting and multicasting. Copyright © 2009 John Wiley & Sons, Ltd.
Interoperable semantic access control for highly dynamic coalitions
Authors: Koshutanski Hristo , Maña Antonio 
Published: September 2009

AbstractA coalition consists of independent organizations that share resources and skills to achieve significant mission objectives. Dynamic Coalition (DC) formations occur in response to some market demands, business requests, or disaster responses, to name a few. Partners forming a coalition are automatically selected given some business criteria and become active participants from the time the coalition is formed. Highly dynamic coalitions (HDCs) form a sub class of dynamic coalitions where the coalition formation and operation are strictly bound by time in order to provide a prompt reaction to some events. This type of dynamism poses the necessity of underlying security models and technologies allowing for automated coalition formation and operation. This paper presents a platform‐driven approach to HDCs. It first defines a life cycle inherent to HDC formations, and then presents a platform‐driven access control model that takes advantage of semantics of partners' requirements to provide interoperable access control to resources shared in a coalition. Coalition partners can achieve a high level of service interoperation by enhancing their access control requirements with semantics of usage, and interlinking their semantics using class relations based on standard ontology. Copyright © 2009 John Wiley & Sons, Ltd.
PAPA‐UIC: a design approach and a framework for secure mobilead hocnetworks
Authors: Zhao Shushan , Aggarwal Akshai 
Published: September 2009

AbstractSecurity of MobileAd hocNetworks (MANETs) is still a hard problem after years of research. We propose a new design approach and a framework for securing a practical type of MANETs. The framework is namedPAPA‐UIC, short forPre‐planned Ad‐hoc Proactive Approach Using Identity‐based Cryptography. In proactive approach, the system starts from a secure status and fortifies this status by protecting packets using cryptography and updating cryptographic keys periodically or when necessary. The proposed scheme addresses the interdependency cycle of secure routing and security services by combining secure routing and key management in one framework. The framework proposes a secure routing protocol (SRP) using identity‐based cryptography and solutions to general problems of identity‐based cryptography. The routing protocol has several improvements over existing ones. The novel ideas to solve key escrow, identity disclosure and identity revocation issues can be integrated into the framework, and can be transplanted to other environments as well. Copyright © 2009 John Wiley & Sons, Ltd.
Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity‐score matched samples
Authors: Austin Peter C. 
Published: September 2009

AbstractThe propensity score is a subject's probability of treatment, conditional on observed baseline covariates. Conditional on the true propensity score, treated and untreated subjects have similar distributions of observed baseline covariates. Propensity‐score matching is a popular method of using the propensity score in the medical literature. Using this approach, matched sets of treated and untreated subjects with similar values of the propensity score are formed. Inferences about treatment effect made using propensity‐score matching are valid only if, in the matched sample, treated and untreated subjects have similar distributions of measured baseline covariates. In this paper we discuss the following methods for assessing whether the propensity score model has been correctly specified: comparing means and prevalences of baseline characteristics using standardized differences; ratios comparing the variance of continuous covariates between treated and untreated subjects; comparison of higher order moments and interactions; five‐number summaries; and graphical methods such as quantile–quantile plots, side‐by‐side boxplots, and non‐parametric density plots for comparing the distribution of baseline covariates between treatment groups. We describe methods to determine the sampling distribution of the standardized difference when the true standardized difference is equal to zero, thereby allowing one to determine the range of standardized differences that are plausible with the propensity score model having been correctly specified. We highlight the limitations of some previously used methods for assessing the adequacy of the specification of the propensity‐score model. In particular, methods based on comparing the distribution of the estimated propensity score between treated and untreated subjects are uninformative. Copyright © 2009 John Wiley & Sons, Ltd.
Missing values in longitudinal dietary data: A multiple imputation approach based on a fully conditional specification
Authors: Nevalainen Jaakko , Kenward Michael G. , Virtanen Suvi M. 
Published: September 2009

AbstractMultiple imputation (MI) has increasingly received attention as a flexible tool to resolve missing data problems both in observational and controlled studies. Our goal has been to develop a valid and efficient MI procedure for the Diabetes Prediction and Prevention Nutrition Study, in which the diet of a cohort of newborn children with HLA‐DQB1‐conferred susceptibility to type 1 diabetes is repeatedly measured by 3‐day food records over early childhood. The estimation of risk is based on a nested case‐control design setup within the cohort. We have used an iterative procedure known as the fully conditional specification (FCS) to generate appropriate values for the missing dietary data, here playing the role of time‐dependent covariates. Our method extends the standard FCS to repeated measurements settings with the possibility of non‐monotone missingness patterns by being doubly iterative over the follow‐up time of the individuals. In addition, our proposed procedure is nonparametric in the sense that the variables can have distributions deviating strongly from normality: it makes use of quantile normal scores to transform to normality, performs imputations, and transforms back to the original scale. By the use of a moving time window and stepwise regression procedures, the two‐fold FCS method operates well with a great number of variables each measured repeatedly over time. Extensive simulation studies demonstrate that the procedure together with the proposed transformations and variable selection methods provides tools for valid and efficient statistical inference in the nested case‐control setting, and its applications extend beyond that. Copyright © 2009 John Wiley & Sons, Ltd.