bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanocrystalline Magnesium Oxide‐Stabilized Palladium(0): An Efficient and Reusable Catalyst for Selective Reduction of Nitro Compounds
Authors: Kantam M. Lakshmi , Chakravarti Rajashree , Pal Ujjwal , Sreedhar B. , Bhargava Suresh 
Published: March 2008

AbstractAn efficient, mild and selective synthesis of aromatic and aliphatic amines from the corresponding nitro compounds has been realized by using a ligand‐free heterogeneous nanocrystalline magnesium oxide‐stabilized palladium(0) catalyst, employing molecular hydrogen as the reductant. The catalyst is recovered quantitatively by simple filtration and was reused for several cycles with consistent activity.
Electrochemical microreactor for chiral syntheses using the cofactor NADH
Authors: Cheikhou Kane , Tzédakis Théodore 
Published: March 2008

AbstractAn electrochemical filter‐press microreactor has been designed by electroerosion to perform chiral enzymatic syntheses. Semicylindrical channels are created in the electrodes, only separated by a Nafion membrane. Electrochemical and hydrodynamic characterization of the microreactor allows operating conditions to be optimized. Continuous enzymatic regeneration of NADH was achieved using flavin adenine dinucleotide (FAD/FADH2) as redox mediator. The high specific surface area of the cathode (250 cm−1) provides favorable conditions to increase the FADH2/FAD concentration ratio and shifts the nonspontaneous reaction FADH2/NAD+ toward regeneration of NADH. Synthesis of chiral L‐lactate from pyruvate, in the presence of L‐LDH, is the model reaction used to check the ability of the microreactor to regenerate NADH; the optimized device allows quantitative yields to be reached in NAD+ conversion and in L‐lactate production. The simulation (FemLab software) results are in good agreement with the experimental mass balances for flow in the range 0.1–0.2 cm3/min. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Filtered two‐fluid models for fluidized gas‐particle suspensions
Authors: Igci Yesim , Andrews Arthur T. , Sundaresan Sankaran , Pannala Sreekanth , O'Brien Thomas 
Published: March 2008

AbstractStarting from a kinetic theory based two‐fluid model for gas‐particle flows, we first construct filtered two‐fluid model equations that average over small scale inhomogeneities that we do not wish to resolve in numerical simulations. We then outline a procedure to extract constitutive models for these filtered two‐fluid models through highly resolved simulations of the kinetic theory based model equations in periodic domains. Two‐ and three‐dimensional simulations show that the closure relations for the filtered two‐fluid models manifest a definite and systematic dependence on the filter size. Linear stability analysis of the filtered two‐fluid model equations reveals that filtering does indeed remove small scale structures that are afforded by the microscopic two‐fluid model. © 2008 American Institute of Chemical Engineers AIChE J, 2008
The continuous depolymerization of filled polytetrafluoroethylene with a continuous process
Authors: van der Walt I. J. , Grunenburg A. T. , Nel J. T. , Maluleke G. G. , Bruinsma O. S. L. 
Published: March 2008

AbstractA new method for beneficiating unfilled as well as filled polytetrafluoroethylene (PTFE) waste has been developed. This process does not use any carrier gas while forming the depolymerization products. It enables polymer manufacturers and end‐users to reuse and adds value to filled fluorocarbon polymer waste. The filler material was qualified by means of scanning electron microscopy and thermogravimetric analysis and the success of the depolymerization process inside a rotating kiln was proved by visual observation. The PTFE was depolymerized inside a kiln‐type reactor declined at a 5° angle, with a central rotating paddle screw to scrape the inner wall of the reactor, which was able to operate within the temperature range of 600–800°C and pressure range of 10–90 kPa. Different ratios of the useful products tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and octafluorocyclobutane (OFCB) were produced. The optimum conditions for TFE production are 600°C and 10–30 kPa, for HFP production it was 800°C and 10 kPa, and for OFCB production 600°C and 90 kPa. Temperatures of 700°C should be avoided as this leads to considerable amounts of undesirable HFE and OFP as well as the very toxic PFIB. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Novel blood‐compatible waterborne polyurethane using chitosan as an extender
Authors: Xu Dan , Meng Zhen , Han Ming , Xi Kai , Jia Xudong , Yu Xuehai , Chen Qingmin 
Published: March 2008

AbstractA series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, Mn = 1000), isophrone diisocyanate (IPDI), and 2,2′‐dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain‐extended by water‐soluble chitosan of low molecular weight (Mn = 5000) by self‐emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Resin. III. Synthesis, characterization, and ion‐exchange properties of a 2,2′‐dihydroxybiphenyl–formaldehyde copolymer resin
Authors: Jadhao Manjusha M. , Paliwal L. J. , Bhave N. S. 
Published: March 2008

AbstractA 2,2′‐dihydroxybiphenyl–formaldehyde copolymer, synthesized by the condensation of 2,2′‐dihydroxybiphenyl with CH2O in the presence of an acid catalyst, proved to be a selective chelating ion‐exchange copolymer for certain metals. The chelating ion‐exchange properties of this copolymer were studied for Fe(III), Cu(II), Ni(II), Zn(II), Cd(II), and Pb(II) ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake, involving the measurements of the distribution of a given metal ion between the copolymer sample and the solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for Fe(III), Cu(II), and Ni(II) ions than for Co(II), Zn(II), Cd(II), and Pb(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation of poly (ethylene oxide)‐graft‐poly (acrylic acid) copolymer stabilized iron oxide nanoparticles via an in situ templated process
Authors: Li Pengpeng , Huang Junlian 
Published: March 2008

AbstractSuperparamagnetic iron oxide nanoparticles were prepared in the presence of poly (ethylene oxide)‐graft‐poly (acrylic acid) copolymers via an in situ templated coprecipitation process. The resulted composite nanoparticles consisted of clusters of iron oxide monocrystals embedded inside the polymer chains, and were highly dispersible in aqueous solution. In these graft copolymers, the PAA segments were chemisorbed onto the Fe3O4 nanoparticle surface through their carboxylic acid groups by forming carboxylate groups with the Fe atoms, while PEO segments as the stabilizers extended into the water matrix. Thus the composite nanoparticles exhibited narrow size distribution by the dynamic light scattering measurement. X‐ray diffraction and magnetometer data confirmed the crystalline structure and superparamagnetic property of the particles. This procedure provided a good choice for preparing stable iron oxide magnetic nanoparticles with PEO modified surfaces. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Crosslinkable poly(vinyl acetate)/clay nanocomposite films cast from soap‐free emulsion‐polymerized latices
Authors: Chien An‐Ting , Lee Yuan‐Haun , Lin King‐Fu 
Published: March 2008

AbstractExfoliated poly(vinyl acetate) (PVAc)/montmorillonite (MMT) and poly(vinyl acetate‐co‐glycidyl methacrylate) [P(VAc‐co‐GMA)]/MMT nanocomposite latices, prepared by soap‐free emulsion polymerization, were able to be cast into films, and the latter was crosslinked with diethylene triamine as a curing agent. The glass‐transition temperature of the crosslinked P(VAc‐co‐GMA)/MMT nanocomposite films was higher than that of the PVAc/MMT counterparts. Although both the Young's modulus and yield stress for the PVAc/MMT nanocomposite films increased with the content of MMT, the extent of the increase was greater for the crosslinked P(VAc‐co‐GMA)/MMT nanocomposites. The exfoliated MMT nanoplatelets retarded the cold drawing of the PVAc matrix during tensile testing, resulting in a decrease of the elongation. However, crosslinked P(VAc‐co‐GMA)/MMT nanocomposite films still had more elongation than the PVAc/MMT counterparts. The drastic decrease of the water vapor permeability with the content of MMT for both types of nanocomposite films suggested that the exfoliated MMT nanoplatelets were dispersed evenly and flattened completely along the film surface. After all the nanocomposite film samples were burned, the inflammable residues for the samples with an MMT content higher than 5 wt % could preserve the original film profile with stiffness, and this indicated that the exfoliated MMT nanoplatelets acted as inflammable scaffolds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Isothermal differential scanning calorimetry study of the cure kinetics of a novel aromatic maleimide with an acetylene terminal
Authors: Luo Zhenhua , Wei Liuhe , Li Wanwan , Liu Feng , Zhao Tong 
Published: March 2008

AbstractAn isothermal differential scanning calorimetry (DSC) study on the cure kinetics was performed on N‐(3‐acetylenephenyl)maleimide (3‐APMI) monomer to determine a suitable cure model. The 3‐APMI monomer reported in our prior article was a novel aromatic maleimide monomer with an acetylene terminal that would be an ideal candidate for heat‐resistant composites. The isothermal DSC study was carried out in the temperature range 150–200°C. Although the cure temperatures were different, the shapes of the conversion curves were similar, and all of the cure reactions could be described by an nth‐order kinetic model. In particular, the cure reaction at the initial stage was a first‐order kinetic reaction. The cure kinetic parameters of the 3‐APMI monomer, including the reaction model, activation energy, and frequency factor, were determined. This information was very useful for defining the process parameters, final properties, and quality control of the cured 3‐APMI monomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Visualization of the flow history contours at the cross‐section of a weld‐line in an injected molded part
Authors: Fathi Saeed , Behravesh Amir Hossein 
Published: March 2008

AbstractThis article presents visualization of flow history contours at the cross‐section of an injection molded part along the weld‐line originated by an obstacle pin in a plate‐shaped cavity. The visualized flow history contours unveiled the interface of the two adjacent flows through which the penetration of one flow front to the other at the interface was observed. The penetration which was the most at the core of the part behind the obstacle pin was inferred to be originated from an eccentricity in the position of the obstacle pin. Applying image processing techniques, a sequence of the variation in the shape of the interface along the weld‐line was extracted from which the amount of penetration at different distances behind the obstacle was measured. Experimental results revealed an oscillation in the direction of the penetration along the weld‐line at the core of the part. A scanning electron microscope micrography was also applied to characterize the V‐notch along the weld‐line at the surface of the molded part. V‐notch characterization was used to investigate the possible correlation between the internal and external behaviors of the molten plastic during weld‐line formation by which an obstruction affected zone at the weld‐line area behind the obstacle pin was distinguished. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and polymerizations of new metal chelating monomers from alkyl α‐hydroxymethacrylates
Authors: Albayrak Aylin Ziylan , Avci Duygu 
Published: March 2008

AbstractTwo new diethyl iminodiacetate‐containing monomers (EBMA‐ID and CMAC‐ID) were synthesized through the reaction of ethyl α‐bromomethacrylate (EBMA) and α‐chloromethacryloylchloride (CMAC) with diethyl iminodiacetate (ID). The hydrolysis of the ethyl ester groups with potassium hydroxide gave two chelating monomers with potassium salt of iminodiacetic acid (EBMA‐IDA‐K+ and CMAC‐IDA‐K+). The homopolymerization and copolymerization with 2‐hydroxyethyl methacrylate (HEMA) of EBMA‐ID and CMAC‐ID were investigated by photodifferential scanning calorimetry at 40°C using 2,2′‐dimethoxy‐2‐phenyl‐acetophenone (DMPA) as initiator. The monomers showed very low homopolymerization reactivity which may be attributed to the steric effect of N,N‐disubstituted methacrylamides, the presence of allyl amine group that can undergo degradative chain transfer and the bulky ID group close to the double bond. Also, addition of these monomers to HEMA decreased polymerization rate and conversion with fraction added. EBMA‐IDA‐K+ and CMAC‐IDA‐K+ were copolymerized with acrylamide in water using 2,2′‐azobis(N,N′‐amidinopropane) dihydrochloride (V‐50) initiator. Here also, it was observed that the incorporation of the synthesized monomers into acrylamide reduced both the rate of polymerization and conversion. The copolymers were characterized by 1H‐NMR spectroscopy, thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The UV‐visible and TGA spectra confirmed that the synthesized monomers showed chelating ability for Ni+2 and Cr+3. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Carboxylated multiwall carbon nanotube‐reinforced thermotropic liquid crystalline polymer nanocomposites
Authors: Park Sang Ki , Kim Seong Hun , Hwang Jin Taek 
Published: March 2008

AbstractThermotropic liquid crystalline polymer (TLCP) nanocomposites reinforced with carboxylated multiwall carbon nanotube (c‐MWCNT) were prepared through melt compounding in a twin screw extruder. The thermal stability of TLCP/c‐MWCNT nanocomposites increased with even a small amount of c‐MWCNT added. The rheological properties of the TLCP/c‐MWCNT nanocomposites were depended on the c‐MWCNT contents. The contents of c‐MWCNT have a slight effect on the complex viscosity of TLCP/c‐MWCNT nanocomposites due to the high‐shear thinning of TLCP. The storage modulus of TLCP/c‐MWCNT nanocomposites was increased with increasing c‐MWCNT content. This result can be deduced that the nanotube–nanotube interactions were more dominant, and some interconnected or network‐like structures were formed in the TLCP/c‐MWCNT nanocomposites. Incorporation of very small amount of c‐MWCNT improved the mechanical properties of TLCP/c‐MWCNT nanocomposites, and this was attributed to the reinforcement effect of c‐MWCNT with high aspect ratio and their uniform dispersion through acid treatment in the TLCP matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Water‐blown rigid and flexible polyurethane foams containing epoxidized soybean oil triglycerides
Authors: Tu Yuan‐Chan , Suppes Galen J. , Hsieh Fu‐Hung 
Published: March 2008

AbstractBoth rigid and flexible water‐blown polyurethane foams were made by replacing 0–50% of Voranol® 490 for rigid foams and Voranol® 4701 for flexible foams in the B‐side of foam formulation by epoxidized soybean oil. For rigid water‐blown polyurethane foams, density, compressive strength, and thermal conductivity were measured. Although there were no significant changes in density, compressive strength decreased and thermal conductivity decreased first and then increased with increasing epoxidized soybean oil. For flexible water‐blown polyurethane foams, density, 50% compression force deflection, 50% constant force deflection, and resilience of foams were measured. Density decreased first and then increased, no changes in 50% compression force deflection first and then increased, increasing 50% constant force deflection, and decreasing resilience with increase in epoxidized soybean oil. It appears that up to 20% of Voranol® 490 could be replaced by epoxidized soybean oil in rigid polyurethane foams. When replacing up to 20% of Voranol® 4701 by epoxidized soybean oil in flexible polyurethane foams, density and 50% compression deflection properties were similar or better than control, but resilience and 50% constant deflection compression properties were inferior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Development and validation of evaluation indicators for a consortium of institutional repositories: A case study of dcollection
Authors: Kim Yong Ho , Kim Hyun Hee 
Published: March 2008

AbstractThis study develops evaluation indicators for a consortium of Korean institutional repositories called “dCollection” and validates the indicators against actual data from the participants of this consortium. The literature review reveals a conceptual framework for institutional repository (IR) evaluation with four categories and 19 items. In developing the initial framework, equal amounts of emphasis are put on the assessments of procedural achievement and actual performance to pinpoint the procedural weaknesses of each IR and to determine its customized solution. A Delphi method of three rounds with the help of IR librarians reveals a converging tendency pertaining to the measures of importance ascribed to the categories and items. Through a focus‐group interview with middle‐ to top‐level managers, 39 indicators derived from 19 items are identified as possessing relevancy, measurability, data availability, and differentiability. Validation of evaluation indicators employs actual evaluation data from 32 university IRs. Factor analysis shows a simpler structural pattern containing 12 factors than that of the structural pattern of the conceptual framework that contains 19 items. Correlation analysis using the factor scores identifies six key factors: Registration Rate, Archiving, Resource Allocation, System Performance, Multifunctionality, and Use Rate. The results from regression analyses suggest that two different approaches can be employed to promote the Use Rate factor. In the content‐oriented approach, the Registration Rate factor is crucial while in the policy‐oriented approach the Archiving factor assumes this role; however, the System Performance factor plays a mediating role for the key factors, thus forming a contingency for either approach.
The association of split hand foot malformation (SHFM) and congenital heart defects
Authors: Elliott Alison M. , Evans Jane A. 
Published: March 2008

AbstractBACKGROUND: Split hand foot malformation (SHFM) (cleft hand, central ray deficiency) is a highly variable malformation that shows genetic heterogeneity with at least five loci mapped to date. SHFM occurs as an isolated finding or in association with other anomalies, including congenital heart defects (CHDs). METHODS: In total 48 SHFM1, 52 SHFM3, 48 SHFM4, 21 SHFM5, and four chromosome 8 patients were evaluated. In addition, we performed a literature review to identify “unmapped” SHFM patients with CHD to evaluate the various etiologies of this combination of findings. The London Dysmorphology Database also served as a resource to identify syndromes with this combination of phenotypic findings. Only patients presenting with both SHFM and CHD were included in the analysis. Classification of CHD among mapped and unmapped SHFM patients was performed utilizing the revised Clark classification. A closer inspection of the types of CHD found in this patient group was performed in order to investigate possible pathogenetic mechanisms. RESULTS: CHDs were found in 10% of SHFM1 patients, 47% of SHFM5 patients, but were not reported in SHFM2, SHFM4 patients, or patients mapped to chromosome 8. Forty‐two syndromic cases and 15 cases of unrecognized syndromes were identified. CONCLUSIONS: The higher frequency of heart defects seen in SHFM1 and SHFM5 of the mapped patient group raises the question as to whether common mechanisms/genetic players are involved. Candidate genes for SHFM1 and SHFM5 include members of the DLX homeobox gene family. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Embryonic development in the reduced folate carrier knockout mouse is modulated by maternal folate supplementation
Authors: Gelineau‐van Waes Janee , Heller Steven , Bauer Linda K. , Wilberding Justin , Maddox Joyce R. , Aleman Francisco , Rosenquist Thomas H. , Finnell Richard H. 
Published: March 2008

AbstractBACKGROUND: The reduced folate carrier (RFC1) is a ubiquitously expressed integral membrane protein that mediates delivery of 5‐methyltetrahydrofolate into mammalian cells. In this study, embryonic/fetal development is characterized in an RFC1 knockout mouse model in which pregnant dams receive different levels of folate supplementation. METHODS: RFC1+/− males were mated to RFC1+/− females, and pregnant dams were treated with vehicle (control) or folic acid (25 or 50 mg/kg) by daily subcutaneous injection (0.1 mL/10 g bwt), beginning on E0.5 and continuing throughout gestation until the time of sacrifice. RESULTS: Without maternal folate supplementation, RFC1 nullizygous embryos die shortly postimplantation. Supplementation of pregnant dams with 25 mg/kg/day folic acid prolongs survival of mutant embryos until E9.5–E10.5, but they are developmentally delayed relative to wild‐type littermates, display a marked absence of erythropoiesis, severe neural tube and limb bud defects, and failure of chorioallantoic fusion. Fgfr2 protein levels are significantly reduced or absent in the extraembryonic membranes of RFC1 nullizygous embryos. Maternal folate supplementation with 50 mg/kg/day results in survival of 22% of RFC1 mutants to E18.5, but they develop with multiple malformations of the eyelids, lungs, heart, and skin. CONCLUSIONS: High doses of daily maternal folate supplementation during embryonic/fetal development are necessary for early postimplantation embryonic viability of RFC1 nullizygous embryos, and play a critical role in chorioallantoic fusion, erythropoiesis, and proper development of the neural tube, limbs, lungs, heart, and skin. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Extremely low frequency (ELF) electric and magnetic field exposure limits: Rationale for basic restrictions used in the development of an Australian standard
Authors: Wood Andrew W. 
Published: March 2008

AbstractThere are large disparities between basic restrictions for exposure to extremely low‐frequency (0–3 kHz) Electric and Magnetic Fields set by two major international bodies. Both bodies agree that these basic restrictions should prevent neuro‐stimulatory effects: the retinal phosphene at frequencies up to a few hundred Hertz and peripheral nervous stimulation (PNS) at higher frequencies. The disparity arises from differences in estimated thresholds and frequency dependence, and whether restrictions should be of tissue induced current density or electric field. This paper argues that the latter metric more directly relates to neurostimulatory processes. By analysing available literature, a threshold for retinal phosphenes occurrence is found to be 56 mV/m (95% Confidence Interval 2–1330 mV/m), with a characteristic frequency of 20 Hz. Similarly, the smallest PNS sensation threshold is identified at 2 V/m (characteristic frequency above 3 kHz). In the case of the former, the large range of uncertainty suggests a ‘power of ten’ value of 100 mV/m. For the latter, because of the small margin between sensation and pain threshold, and because of the large individual variation, the smallest estimate of sensation threshold (2 V/m) represents a basic restriction with precaution incorporated. Bioelectromagnetics 29:414–428, 2008. © 2008 Wiley‐Liss, Inc.