bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of polyamic acid on curing behavior, thermal stability, and mechanical properties of epoxy/DDS system
Authors: Yong Liu , Wei Wu , Yu Chen , Pinpin Shi , Mingchang Liu , Xiang Wu 
Published: May 2012

AbstractA thermoplastic modification method was studied for the purpose of improving the toughness and heat resistance and decreasing the curing temperature of the cured epoxy/4, 4′‐diaminodiphenyl sulfone resin system. A polyimide precursor‐polyamic acid (PAA) was used as the modifier which can react with epoxy. The effects of PAA on curing temperature, thermal stability and mechanical properties were investigated. The initial curing temperature (Ti) of the resin with 5 wt % PAA decreased about 50°C. The onset temperature of thermal decomposition and 10 wt %‐weight‐loss temperature for the resin system containing 2 wt % PAA increased about 60°C and 15°C respectively. Besides, the value of impact toughness and plain strain fracture toughness for the modified epoxy resin increased ∼ 190% and 55%, respectively. Those changes were attributed to the outstanding thermal and mechanical properties of polyimide, and more importantly to formation of semi‐interpenetrating polymer networks composed by the epoxy network and linear PAA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Novel fabrication of disorderly exfoliated sodium montmorillonite in a styrene–butadiene rubber matrix
Authors: Wang Qingguo , Zhong Yuan , Zhang Xiaohong , Song Zhihai 
Published: May 2012

AbstractUsing industrial technologies, we prepared a sodium montmorillonite (Na‐MMT) slurry and an irradiated styrene–butadiene rubber (SBR) latex, and then spray dried them to produce a novel, ultrafine fully vulcanized powder SBR (UFPSBR)/Na‐MMT nanocompound powder in which the nanoscale UFPSBR particles and exfoliated Na‐MMT were isolated and stuck together. When the UFPSBR/Na‐MMT nanocompound powder was mixed with crude SBR, the exfoliated Na‐MMT was disorderly dispersed in the SBR matrix because of the carrier nature of the UFPSBR particle, which is compatible with SBR and disperses easily in the SBR matrix, and the SBR/UFPSBR/Na‐MMT ternary nanocomposite was prepared. When compared with SBR/Na‐MMT binary composites, the SBR/UFPSBR/Na‐MMT ternary nanocomposite has a shorter vulcanization time, higher strength, and better flame retardancy because of the good dispersion of exfoliated Na‐MMT in the SBR matrix with a Na‐MMT loading range of 4 phr. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2013
Biocompatibility evaluation of glycolide‐containing polyesters in contact with osteoblasts and fibroblasts
Authors: Scislowska‐Czarnecka Anna , Pamula Elzbieta , Kolaczkowska Elzbieta 
Published: May 2012

AbstractBiodegradable aliphatic polyesters have numerous biomedical applications and their capacity to degrade in biological fluids provides the significant advantage of their removal. Three glycolide‐containing aliphatic polyesters: a copolymer of glycolide and L‐lactide (PGLA), a terpolymer of glycolide, L‐lactide and ε‐caprolactone (PGLCap) and a copolymer of glycolide, and ε‐caprolactone (PGCap) were tested to evaluate their biocompatibility towards osteoblasts and fibroblasts. Each of the polymer units was previously reported to have acceptable biological properties and good biodegradability, and PGLA is already used for biomedical applications. Here we report that both PGLCap and PGCap affected cell adherence, and compromised cell viability as estimated by flow cytometric analyses of apoptotic and necrotic cells. The two polymers enhanced also production of numerous inflammation‐related factors: nitric oxide, matrix metalloproteinases (MMP‐2 and MMP‐9), and cytokines, including pro‐inflammatory TNF‐α, IL‐1β, IL‐6, and chemokines (IL‐8 or MCP‐1) attracting leukocytes. The effects of PGLCap and PGCap were similar despite the fact that they possess different characteristics: amorphous/smooth surface and semicristalline/rough surface, respectively. However, their common feature, distinctive from PGLA, is a presence of ε‐caprolactone units in their structure. This compound is considered to be acceptably biocompatible but our data suggest that its copolymerization with glycolide and L‐lactide does not provide satisfactory biocompatibility towards osteoblasts and fibroblasts. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Thermoresponsive sodium alginate‐g‐poly(N‐isopropylacrylamide) copolymers III. Solution properties
Authors: Cheaburu Catalina Natalia , Ciocoiu Oana‐Nicoleta , Staikos Georgios , Vasile Cornelia 
Published: May 2012

AbstractStimuli‐responsive biocompatible and biodegradable materials can be obtained by combining polysaccharides with polymers exhibiting lower critical solution temperature (LCST) phase behavior, such as poly(N‐isopropylacrylamide) (PNIPAAm). The behavior of aqueous solutions of sodium alginate (NaAl) grafted with PNIPAAm (NaAl‐g‐PNIPAAm) copolymers as a function of composition and temperature is presented. The products obtained exhibit a remarkable thermothickening behavior in aqueous solutions if the degree of grafting, the concentration, and the temperature are higher than some critical values. The sol–gel‐phase transition temperatures have been determined. It was found that at temperatures below LCST the systems behave like a solution, whereas at temperatures above LCST, the solutions behave like a stiff gel, because of PNIPAAm segregation. This behavior is reversible and could find applications in tissue engineering and drug delivery systems. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Phenomenological‐based kinetics modelling of dehydrogenation of ethylbenzene to styrene over a Mg3Fe0.25Mn0.25Al0.5 hydrotalcite catalyst
Authors: Hossain Mohammad M. , Atanda Luqman , Al‐Khattaf Sulaiman 
Published: May 2012

AbstractThis communication reports a mechanism‐based kinetics modelling for the dehydrogenation of ethylbenzene to styrene (ST) using Mg3Fe0.25Mn0.25Al0.5 catalyst. Physicochemical characterisation of the catalyst indicates that the presence of basic sites Mg2+O2− on the catalysts along with Fe3+ is responsible for the catalytic activity. The kinetics experiments are developed using a CREC Fluidised Riser Simulator. Based on the experimental observations and the possible mechanism of the various elementary steps, Langmuir–Hinshelwood type kinetics model are developed. To take into account of the possible catalyst deactivation a reactant conversion‐based deactivation function is also introduced into the model. Parameters are estimated by fitting of the experimental data implemented in MATLAB. Results show that one site type Langmuir–Hinshelwood model appropriately describes the experimental data, with adequate statistical fitting indicators and also satisfied the thermodynamic restraints. The estimated heat of adsorptions of EB (64 kJ/mole) is comparable to the values available in the literature. The activation energy for the formation of ST (85.5 kJ/mole) found to be significantly lower than that of the cracking product benzene (136.6 kJ/mole). These results are highly desirable in order to achieve high selectivity of the desired product ST. © 2012 Canadian Society for Chemical Engineering
Accumulation of weathered p,p′-DDTs in hybridized Cucurbita pepo cultivars
Authors: Isleyen Mehmet , Sevim Pinar , White Jason C. 
Published: May 2012

Abstract
Cucurbita pepo spp pepo (zucchini) is known as an exceptional weathered dichlorodiphenyldichloroethylene (DDE) accumulator, whereas Cucurbita pepo ssp ovifera (squash) is termed a nonaccumulator. Experiments were conducted with hybridized zucchini and squash to assess the inheritance pattern of DDX (the sum of p,p′-dichlorodiphenyltrichloroethane [p,p′-DDT], p,p′-dichlorodiphenyldichloroethane [p,p′-DDD], and p,p′-dichlorodiphenyldichloroethylene [p,p′-DDE]) accumulation potential in xylem sap and tissues of parental, F1 hybrids, and F1 backcross (BC) generations of plants. Plants were grown in pots containing soil with weathered DDX at 732 to 1,130 ng/g soil or under field conditions in soil with 322 to 2,700 ng/g. The DDX stem bioconcentration factors and xylem sap values showed differences between parental and hybridized plants of squash and zucchini. For squash grown in greenhouse conditions, the DDX flow rate in the xylem sap was 17.3, 121, and 40.8 ng/h in parental, F1 hybrids, and F1 BC plants, respectively. Similarly, the stem DDX content of parental, F1, and F1 BC squash was 11, 253, and 96 ng/g (dry wt), respectively. A similar inheritance pattern for squash was observed when the plants were grown under field conditions. The DDX flow rates in the xylem sap of pot-grown parental, F1, and F1 BC zucchini cultivars were 100, 8.5, and 26 ng/hr, respectively, and the stem DDX content was 191, 102, and 142 ng/g, respectively. Again, similar trends in accumulation potential were observed for hybridized zucchini grown under field conditions. The DDX concentrations in parental plants matched the expected pattern, with hybrids midway between the two species, and the backcross being more like the parent again for both species. This inheritance pattern of contaminant accumulation and translocation ability follows classical Mendelian segregation and suggests single-gene or single-locus control. Environ. Toxicol. Chem. 2012; 31: 1699–1704. © 2012 SETAC
Toxicity of carbon nanotubes to freshwater aquatic invertebrates
Authors: Mwangi Joseph N. , Wang Ning , Ingersoll Christopher G. , Hardesty Doug K. , Brunson Eric L. , Li Hao , Deng Baolin 
Published: May 2012

Abstract
Carbon nanotubes (CNTs) are hydrophobic in nature and thus tend to accumulate in sediments if released into aquatic environments. As part of our overall effort to examine the toxicity of carbon-based nanomaterials to sediment-dwelling invertebrates, we have evaluated the toxicity of different types of CNTs in 14-d water-only exposures to an amphipod (Hyalella azteca), a midge (Chironomus dilutus), an oligochaete (Lumbriculus variegatus), and a mussel (Villosa iris) in advance of conducting whole-sediment toxicity tests with CNTs. The results of these toxicity tests conducted with CNTs added to water showed that 1.00 g/L (dry wt) of commercial sources of CNTs significantly reduced the survival or growth of the invertebrates. Toxicity was influenced by the type and source of the CNTs, by whether the materials were precleaned by acid, by whether sonication was used to disperse the materials, and by species of the test organisms. Light and electron microscope imaging of the surviving test organisms showed the presence of CNTs in the gut as well as on the outer surface of the test organisms, although no evidence was observed to show penetration of CNTs through cell membranes. The present study demonstrated that both the metals solubilized from CNTs such as nickel and the “metal-free” CNTs contributed to the toxicity. Environ. Toxicol. Chem. 2012; 31: 1823–1830. © 2012 SETAC
Different profiles of hepatic alkoxyresorufin O‐dealkylase activities in small rodents
Authors: Chatuphonprasert Waranya , Rermraksakul Papimon , Udomsuk Latiporn , Lao‐ong Thinnakorn , Jarukamjorn Kanokwan 
Published: May 2012

ABSTRACTThe aims of the present study were to determine cytochrome P450 enzyme activity in six strains of experimental rodents (n = 5/sex/species): ICR, C57BL/6 and DBA/2 mice; Sprague Dawley and Wistar rats; and Dunkin Hartley guinea pigs. After animals were treated with the typical inducers β‐naphthoflavone (BNF), dexamethasone (DEX) and phenobarbital (PB), the levels of O‐dealkylation of ethoxyresorufin (EROD), methoxyresorufin (MROD), pentoxyresorufin (PROD) and benzyloxyresorufin (BROD) activity were determined using responsive catalytic reactions to study CYP1A1, CYP1A2 and CYP2B, respectively. A maximal induction of EROD and MROD was found in BNF‐treated animals from all strains (2.4‐ to 15.1‐fold) except DBA/2 (0.9‐ to 1.8‐fold). C57BL/6 mice had the strongest BNF‐induced EROD (15.1‐fold) and MROD (8.3‐fold) activities. No differences in BNF‐induced EROD and MROD activities were observed between males and females. However, the EROD activity of Wistar rats and the MROD activity of Sprague Dawley rats were higher in males than females. DEX induced PROD activity only in mice (1.3‐ to 7.1‐fold), but not in rats and guinea pigs (0.2‐ to 1.1‐fold). However, induction of BROD activity was found in DEX‐treated mice and rats (1.5 to 12.5‐fold), but not in guinea pigs (0.3 to 0.4‐fold). PB caused a significant elevation of PROD (1.7‐ to 10.4‐fold) and BROD (31‐ to 13.2‐fold) activities in all the animals. PB‐induced BROD activity was higher in females than males in Sprague Dawley rats. These observations strongly suggest that the choice of experimental animal strain, species and inducer is of critical importance for studies of drug metabolism and interaction. Copyright © 2012 John Wiley & Sons, Ltd.
Usefulness of administration of non‐organophosphate cholinesterase inhibitors before acute exposure to organophosphates: assessment using paraoxon
Authors: Petroianu Georg A. , Nurulain Syed M. , Shafiullah Mohamed , Hasan Mohamed Y. , Kuča Kamil , Lorke Dietrich E. 
Published: May 2012

ABSTRACTReversible acetylcholinesterase (AChE) inhibitors can protect against the lethal effects of irreversible organophosphorus AChE inhibitors (OPCs), when administered before OPC exposure. We have assessed in vivo the mortality‐reducing efficacy of a group of known AChE inhibitors, when given in equitoxic dosage before exposure to the OPC paraoxon. Protection was quantified in rats by determining the relative risk (RR) of death.Best in vivo protection from paraoxon‐induced mortality was observed after prophylactic administration of physostigmine (RR = 0.30) or the oxime K‐27 (RR = 0.34); both treatments were significantly superior to the pre‐treatment with all other tested compounds, including the established substance pyridostigmine. Tacrine (RR = 0.67), ranitidine (RR = 0.72), pyridostigmine (RR = 0.76), tiapride (RR = 0.80) and 7‐MEOTA (RR = 0.86) also significantly reduced the relative risk of paraoxon‐induced death, but to a lesser degree. Methylene blue, amiloride and metoclopramide had an unfavorable effect (RR ≥ 1), significantly increasing mortality. When CNS penetration by prophylactic is undesirable K‐27 is a promising alternative to pyridostigmine. Copyright © 2012 John Wiley & Sons, Ltd.
In vivo protective effect of Copaifera langsdorffii hydroalcoholic extract on micronuclei induction by doxorubicin
Authors: Alves Jacqueline Morais , Munari Carla Carolina , de Azevedo Bentes Monteiro Neto Moacir , Furtado Ricardo Andrade , Senedese Juliana Marques , Bastos Jairo Kenupp , Tavares Denise Crispim 
Published: May 2012

ABSTRACTCopaifera lansdorffii Desf. is known as ‘copaíba’, ‘copaiva’ or ‘paú‐de‐óleo’, and is found in part of Brazil. The present study was undertaken to evaluate the genotoxic potential of C. langsdorffii leaf hydroalcoholic extract (CLE) and its influence on the genotoxicity induced by the chemotherapeutic agent doxorubicin (DXR) using the Swiss mouse peripheral blood micronucleus test. HPLC analysis of CLE using two monolithic columns linked in series allowed quantification of two major flavonoid heterosides, quercitrin and afzelin. Animals were treated with CLE by gavage at doses of 10, 20, 40 and 80 mg kg−1 body weight per day, each for 20 days. Peripheral blood samples were collected at 24 and 48 h, and 7, 15 and 21 days after the beginning of the treatment. For the antigenotoxicity evaluation, the animals treated with different concentrations of CLE received DXR (15 mg kg−1 body weight, intraperitoneal) at day 20. The peripheral blood samples were collected 24 and 48 h after the treatment with DXR. The results demonstrated that CLE itself was not genotoxic in the mouse micronucleus assay. In animals treated with CLE and DXR, the number of micronucleus was significantly decreased compared with animals receiving DXR alone. The putative antioxidant activity of one or more of the active compounds of CLE may explain the effect of this plant on DXR genotoxicity. Copyright © 2012 John Wiley & Sons, Ltd.
Hoechst increases adeno‐associated virus‐mediated transgene expression in airway epithelia by inducing the cytomegalovirus promoter
Authors: Dickey David D. , Excoffon Katherine J. D. A. , Young Krista R. , Parekh Kalpaj R. , Zabner Joseph 
Published: May 2012

AbstractBackgroundIn airway epithelia, the kinetics of recombinant adeno‐associated virus (AAV) transgene expression is slow. This has negative practical implications for research, as well as for translation into therapy. The DNA minor groove‐binding agent Hoechst‐33342 has been shown to enhance AAV transgene expression. In the present study, we investigated the mechanism of Hoechst‐related augmentation of AAV‐mediated transgene expression.MethodsWe investigated the effect of Hoechst‐33342 on HT1080, COS‐7, mouse and human airway epithelia transduced with different AAV serotypes encoding enhanced green fluorescent protein (eGFP). We exposed cells to increasing concentrations of Hoechst‐33342 at different time points. We evaluated the effect on second‐strand DNA synthesis using AAV with a self‐complementary genome. We also investigated the effect on expression from transfected plasmids with and without AAV2 inverted terminal repeats (ITRs).ResultsWe found that Hoechst‐33342 significantly accelerated AAV transgene expression for all serotypes tested. Hoechst‐33342 only had an effect when the treatment was given during or after transduction, even 120 days post‐transduction, suggesting an effect on transgene expression regulation. Hoechst‐33342 increased transgene expression when cells were transduced with a self‐complementary AAV with the cytomegalovirus promoter, although there was no effect on cells transduced with conventional single‐stranded AAV encoding the Rous sarcoma virus promoter. Finally, Hoechst‐33342 increases gene expression from transfected plasmids regardless of the presence of AAV2 ITRs.ConclusionsHoechst dramatically augments and accelerates AAV‐mediated transgene expression in airway epithelia without altering AAV‐mediated gene transfer. Hoechst activation of the cytomegalovirus promoter is seen in plasmids, although it is drastically enhanced in the context of AAV. Copyright © 2012 John Wiley & Sons, Ltd.
Γ‐convergence: a tool to investigate physical phenomena across scales
Authors: Focardi Matteo 
Published: May 2012

De Giorgi's Γ‐convergence is a variational theory modelled upon the convergence of families of (perturbed) minimum problems and of the corresponding minimizers.In these notes, after reviewing briefly the basic theory and accounting for some recent new insights, we discuss three examples of static mechanical models, which can be analysed by means of Γ‐convergence arguments. Copyright © 2012 John Wiley & Sons, Ltd.
Simple linear flow decomposition algorithms on trees, circles, and augmented trees
Authors: Vaidyanathan Balachandran 
Published: May 2012

AbstractThe flow decomposition algorithm transforms an arc flow‐based solution to a network flow problem into flows on directed paths and cycles. When the undirected graph induced by arcs with positive flow is a tree, a circle, or an augmented tree (with n nodes), the standard implementation of the algorithm runs in O (n2) time. In this article, we exploit the structure of the network to develop an O (n) flow decomposition algorithm. The run‐time relies on the property that for these networks, paths or cycles can be represented implicitly in O (1) space. The algorithm is easy to implement and does not use complicated data structures. Because the size of the input is O (n), our algorithm is the fastest possible for flow decomposition on these special networks. Our algorithm can be used to improve run‐times for solving matching and transportation problems on trees and circles. © 2012 Wiley Periodicals, Inc. NETWORKS, 2012
Robust mean absolute deviation problems on networks with linear vertex weights
Authors: López‐de‐los‐Mozos M.C. , Puerto J. , Rodríguez‐Chía A.M. 
Published: May 2012

AbstractThis article deals with incorporating the mean absolute deviation objective function in several robust single facility location models on networks with dynamic evolution of node weights, which are modeled by means of linear functions of a parameter. Specifically, we have considered two robustness criteria applied to the mean absolute deviation problem: the MinMax criterion, and the MinMax regret criterion. For solving the corresponding optimization problems, exact algorithms have been proposed and their complexities have been also analyzed. © 2012 Wiley Periodicals, Inc. NETWORKS, 2013
Can students run their own interventions?: A self‐administered math fluency intervention
Authors: Hulac David M. , Dejong Kayla , Benson Nicholas 
Published: May 2012

AbstractManipulating the ratio of known to unknown items has been shown to improve student on‐task behavior and increase the desirability of schoolwork. Although many intervention protocols manipulate ratios of known to unknown items, these frequently require extensive adult cuing. School psychologists recommending such interventions may face resistance from teachers who find the work to be too time intensive. Self‐administered interventions whereby the students act as primary interventionists may alleviate this concern. A modified multiple baseline design across a group of 11 students identified by their teachers as having difficulty mastering multiplication facts was used to evaluate a self‐administered folding‐in technique. As hypothesized, for the overall sample, stronger effects were observed on math curriculum‐based measures (CBM) than on a control reading task (Maze CBM). Individually, 7 of the 11 students demonstrated higher levels of growth during the intervention phase than during the baseline phase. No student demonstrated higher Maze CBM growth rates during the intervention phase relative to the baseline phase. In contrast, of the 4 students for whom a link between the intervention and the baseline could not be established, 3 demonstrated higher levels of performance on math CBMs following the intervention phase. Results are discussed in light of a response‐to‐intervention model. © 2012 Wiley Periodicals, Inc.