bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization behavior and phase‐transformation mechanism with the use of graphite nanosheets in poly(vinylidene fluoride) nanocomposites
Authors: Zhang Y. Y. , Jiang S. L. , Yu Y. , Zeng Y. K. , Zhang G. Z. , Zhang. Q. F. , He J. G. 
Published: January 2012

AbstractPoly(vinylidene fluoride) (PVDF)–graphite nanosheet (GNS) nanocomposites with different contents of GNSs were prepared by the solution‐casting method. The GNSs were produced by the ultrasonic exfoliation of graphite. The effects of GNSs on the crystalline structure, degree of the crystallization, conductivity, and phase‐transformation mechanism of PVDF were investigated. Atomic force microscopy data showed that the GNSs had a flake‐shaped nanostructure. Fourier transform infrared spectroscopy and X‐ray diffraction results revealed that a β phase formed with the addition of GNSs, and the phase‐transformation mechanism from the α phase to the β phase of PVDF was confirmed. Differential scanning calorimetry results indicated that addition of GNSs led to an increased melting temperature and increased degree of crystallization; this implied that the GNSs acted as nucleating agents. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Kinetic study of the polymerization of dimethyldiallylammonium chloride and acrylamide
Authors: Bi Kezhen , Zhang Yuejun 
Published: January 2012

AbstractThe kinetics of the polymerization of dimethyldiallylammonium chloride (DMDAAC) and acrylamide (AM) with different monomer molar ratios initiated by an ammonium persulfate–sodium bisulfate redox complex in an aqueous solution were studied. The polymerization rate (Rp) equation, the activation energy (Ea), and the reactivity ratio were measured. The results show that when the nDMDAAC:nAM values were 1 : 9, 2 : 8, 3 : 7, 4 : 6, and 5 : 5, the copolymerization rate equation were Rp1 = k[M]2.61[IO]0.51[IR]0.52, Rp2 = k[M]2.70[IO]0.50[IR]0.53, Rp3 = k[M]2.73[IO]0.50[IR]0.56, Rp4 = k[M]2.77[IO]0.51[IR]0.59, and Rp5 = k[M]2.84[IO]0.51[IR]0.61 (where [M] is the total monomer concentration, [IO] is the oxidant concentration, and [IR] is the reductant concentration), respectively when the temperature was 45°C. The Ea values were Ea1 = 79.10 kJ/mol, Ea2 = 81.39 kJ/mol, Ea3 = 85.15 kJ/mol, Ea4 = 88.88 kJ/mol, and Ea5 = 90.61 kJ/mol in the temperature range 35–55°C, respectively. The reactivity ratios of DMDAAC and AM were rDMDAAC = 0.14 and rAM = 6.11 when the temperature was 45°C. The structure of PDA was characterized by Fourier transform infrared spectroscopy and 1H‐NMR. The results of the kinetic parameters explained the differences in the copolymerization rate and intrinsic viscosity of PDA with different cationicities. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Isolation of cellulose nanofibers from para rubberwood and their reinforcing effect in poly(vinyl alcohol) composites
Authors: Kamphunthong Walailuck , Hornsby Peter , Sirisinha Kalyanee 
Published: January 2012

AbstractIn this article, we present an efficient method for isolating cellulose nanofibers from para rubberwood sawdust with a combination of chemical, mechanical, and ultrasonic treatments. The effects of the alkali concentration and treatment pathway on the cellulose structure and properties are discussed. The reinforcing efficiency of the resulting fibers on poly(vinyl alcohol) (PVA) composites was characterized. Field emission scanning electron microscopy and atomic force microscopy results revealed a well‐organized network of the nanofibers with diameters in the range 20–80 nm and lengths of micrometer‐scale dimensions. Fibers with a high crystallinity of 83% having a cellulose I structure were prepared by an isolation process involving a mild alkali solution and delignification before acid hydrolysis. Clear composite films with significant improvements in their modulus (by 100%) and strength (by 80%) were obtained by the addition of 7 wt % fiber. Strong interaction between the fibers and PVA was evident from dynamic mechanical analysis and differential scanning calorimetry. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Corrosion protection of mild steel with nanofibrous polyaniline‐based coatings
Authors: Ma Sude , Song Guolin , Feng Ningbo , Zhao Pei 
Published: January 2012

AbstractPolyaniline (PANI) nanofibers were successfully synthesized by a modified rapid mixing method, that is, by the rapid mixing of solutions of aniline and ammonium peroxydisulfate in either hydrochloric acid or filtrates of oxidative polymerization of aniline. Scanning electron microscopy examination showed that nanofibrous PANI products were achieved in all cases; this indicated that the initially presented excessive anions and cations had no evident effect on the formation of nanosized PANI. The nanofibrous PANI exhibited excellent dispersability in both water and organic solvents, and an ultraviolet–visible spectrum was successfully recorded by dispersion in cyclohexanone. Composite coatings were fabricated with the dispersions of nanofibrous PANI and solutions of epoxy. Greatly enhanced corrosion protection performances were demonstrated by the coatings loaded with a small quantity of nanofibrous PANI. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation, morphology, and properties of conducting polyaniline‐grafted multiwalled carbon nanotubes/epoxy composites
Authors: Xu Jun , Yao Pei , Jiang Zhongyi , Liu Huijun , Li Xuan , Liu Litao , Li Mei , Zheng Yingzhe 
Published: January 2012

AbstractPolyaniline‐grafted multiwalled carbon nanotubes (PANI‐g‐MWNTs)/epoxy composites were prepared by solution blending and mould casting. Transmission electron microscope, scanning electron microscope, differential scanning calorimetry, thermogravimetric analysis, electrical conductivity measurement, and tensile and flexural measurements were used to characterize the morphology, thermal, electrical, and mechanical properties of the composites. The results showed that MWNTs were encapsulated by conducting dodecyl benzene sulfonic acid‐doped PANI forming a core (MWNTs)–shell (PANI) nanostructure. PANI coatings swelled in tetrahydrofuran and MWNTs were homogenously dispersed in epoxy matrix. With PANI‐g‐MWNTs introducing into epoxy resin, curing reaction was promoted and thermal stability of the composites was enhanced. Because of conducting PANI chains wrapping on the surface of MWNTs and well dispersion of MWNTs in epoxy matrix, electrical conductivity at room temperature of the composites was increased by seven orders of magnitude compared with neat epoxy. In the PANI‐g‐MWNTs/epoxy composites, terminal amino groups of PANI coatings reacted with epoxy matrix during curing reactions, which guaranteed interfacial adhesion between MWNTs and epoxy resin. Mechanical properties including tensile strength, Young's modulus, flexural strength, and flexural modulus of the composites were increased by 61%, 43%, 78%, and 49% compared with neat epoxy, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Interfacial enhancement of maleated polypropylene/silica composites using graphene oxide
Authors: Luo Feng , Chen Li , Ning Nanying , Wang Ke , Chen Feng , Fu Qiang 
Published: January 2012

AbstractGraphene oxide (GO) is derived from oxidization of natural graphite and contains many active groups. These active groups make GO a potential compatibilizer for polymer blends or coupling agent for polymer composites. In this work, a novel core‐shell structured hybrid submicroparticles of graphene oxide‐encapsulated silica (GO‐SiO2) were fabricated using GO sheets via an electrostatic assembly between ultrathin negatively charged graphene oxide sheets and positively charged amino‐modified silica. The possible application of this new hybrid filler was explored in preparation of maleated polypropylene (PP‐g‐MA)/GO‐SiO2 composites. The microstructure and interface enhancement of the prepared composites were analyzed by SEM, TEM, OM, TGA, FTIR, and DMA measurements. A uniform dispersion of GO‐SiO2 hybrids, enhanced interfacial adhesion and improved mechanical property were evidenced. The reason might be that graphene oxide can be covalently assembled onto the amino‐modified silica surface, and simultaneously it provides strong interaction with the PP‐g‐MA due to similar polarity or possible hydrogen bonding. This work suggests a potential application of graphene oxide‐encapsulated particle in preparation of high performance polymer composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of solvent swell and bound rubber on wax solubility of carbon black‐reinforced NR composite
Authors: Choi Sung‐Seen , Im Song‐Hee , Nah Changwoon 
Published: January 2012

AbstractWax in a rubber article migrates to the surface and plays the role of an antidegradant by formation of an impervious barrier on the surface. Wax solubility of a rubber article is important for understanding migration behaviors and film formation of wax as well as for determining the proper content of wax in a rubber compound. Wax solubilities of natural rubber composites reinforced with carbon black were measured using wax solution in toluene. A variation of the wax solubility with the carbon black content was investigated. Raw wax solubility decreased with the increase of carbon black content. Solvent swell‐corrected wax solubility also decreased with the carbon black content. The raw wax solubilities were corrected with the rubber fractions, total bound rubber contents, and tightly bound rubber contents as well as the solvent swelling ratio to investigate the influencing parameters on wax solubility. It was found that the unbound and loosely bound rubber fractions as well as the solvent swelling enhanced the wax solubility while the tightly bound rubber fraction reduced it. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The Use of Electromagnetic Induction in Locating Graves and Mapping Cemeteries: an Example from Native North America
Authors: Bigman Daniel P. 
Published: January 2012

ABSTRACTOne of the most popular applications of geophysics to archaeological problems has been to locate unmarked graves and map cemeteries. Although electromagnetic (EM) induction was one of the early techniques used in such applications, alternative techniques such as ground‐penetrating radar and resistivity have become more popular in recent years. Despite some of the method's drawbacks the EM method still presents numerous advantages such as speed in data collection and collection in a variety of survey environments and ground cover. A case study from Ocmulgee National Monument, USA is presented that identified numerous anomalies that may be interpreted as Native American burials. Small anomalies having low apparent conductivity were distributed near the Funeral Mound (Mound C); a known cemetery. The conductivity survey redefined the spatial extent of the cemetery and increased our understanding of burial density. The data collected during the 2010 field season will aid in conservation efforts and help the US National Park Service avoid these sensitive materials during future archaeological work and park management. Copyright © 2012 John Wiley & Sons, Ltd.
β‐Cyclodextrin‐Platinum Nanoparticles/Graphene Nanohybrids: Enhanced Sensitivity for Electrochemical Detection of Naphthol Isomers
Authors: Zhu Gangbing , Gai Pengbo , Wu Liang , Zhang Jianhui , Zhang Xiaohua , Chen Jinhua 
Published: January 2012

AbstractNaphthol isomers, including α‐naphthol (α‐NAP) and β‐naphthol (β‐NAP), are used widely in various fields and are harmful to the environment and human health. The qualitative and quantitative determination of naphthol isomers is therefore of great significance. Herein, β‐cyclodextrin (β‐CD)‐platinum nanoparticles (Pt NPs)/graphene nanosheets (GNs) nanohybrids (β‐CD‐PtNPs/GNs) were prepared for the first time using a simple wet chemical method and characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical methods, and then applied successfully in the ultrasensitive electrochemical detection of naphthol isomers. The results show that the oxidation peak currents of naphthol isomers obtained at the glassy carbon (GC) electrode modified with β‐CD‐PtNPs/GNs are much higher than those at the β‐CD/GNs/GC, PtNPs/GNs/GC, GNs/GC, and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about one order of magnitude for α‐NAP (0.23 nM) and three orders of magnitude for β ‐NAP (0.37 nM).
Friction coefficients for mechanically damaged bovine articular cartilage
Authors: Shi Liu , Brunski Daniel B. , Sikavitsas Vassilios I. , Johnson Matthew B. , Striolo Alberto 
Published: January 2012

AbstractWe used a pin‐on‐disc tribometer to measure the friction coefficient of both pristine and mechanically damaged cartilage samples in the presence of different lubricant solutions. The experimental set up maximizes the lubrication mechanism due to interstitial fluid pressurization. In phosphate buffer solution (PBS), the measured friction coefficient increases with the level of damage. The main result is that when poly(ethylene oxide) (PEO) or hyaluronic acid (HA) are dissolved in PBS, or when synovial fluid (SF) is used as lubricant, the friction coefficients measured for damaged cartilage samples are only slightly larger than those obtained for pristine cartilage samples, indicating that the surface damage is in part alleviated by the presence of the various lubricants. Among the lubricants considered, 100 mg/mL of 100,000 Da MW PEO in PBS appears to be as effective as SF. We attempted to discriminate the lubrication mechanism enhanced by the various compounds. The lubricants viscosity was measured at shear rates comparable to those employed in the friction experiments, and a quartz crystal microbalance with dissipation monitoring was used to study the adsorption of PEO, HA, and SF components on collagen type II adlayers pre‐formed on hydroxyapatite. Under the shear rates considered the viscosity of SF is slightly larger than that of PBS, but lower than that of lubricant formulations containing HA or PEO. Neither PEO nor HA showed strong adsorption on collagen adlayers, while evidence of adsorption was found for SF. Combined, these results suggest that synovial fluid is likely to enhance boundary lubrication. It is possible that all three formulations enhance lubrication via the interstitial fluid pressurization mechanism, maximized by the experimental set up adopted in our friction tests. Biotechnol. Bioeng. 2012; 109:1769–1778. © 2012 Wiley Periodicals, Inc.
Genome‐scale metabolic representation of Amycolatopsis balhimycina
Authors: Vongsangnak Wanwipa , Figueiredo Luís Filipe , Förster Jochen , Weber Tilmann , Thykaer Jette , Stegmann Evi , Wohlleben Wolfgang , Nielsen Jens 
Published: January 2012

AbstractInfection caused by methicillin‐resistant Staphylococcus aureus (MRSA) is an increasing societal problem. Typically, glycopeptide antibiotics are used in the treatment of these infections. The most comprehensively studied glycopeptide antibiotic biosynthetic pathway is that of balhimycin biosynthesis in Amycolatopsis balhimycina. The balhimycin yield obtained by A. balhimycina is, however, low and there is therefore a need to improve balhimycin production. In this study, we performed genome sequencing, assembly and annotation analysis of A. balhimycina and further used these annotated data to reconstruct a genome‐scale metabolic model for the organism. Here we generated an almost complete A. balhimycina genome sequence comprising 10,562,587 base pairs assembled into 2,153 contigs. The high GC‐genome (∼69%) includes 8,585 open reading frames (ORFs). We used our integrative toolbox called SEQTOR for functional annotation and then integrated annotated data with biochemical and physiological information available for this organism to reconstruct a genome‐scale metabolic model of A. balhimycina. The resulting metabolic model contains 583 ORFs as protein encoding genes (7% of the predicted 8,585 ORFs), 407 EC numbers, 647 metabolites and 1,363 metabolic reactions. During the analysis of the metabolic model, linear, quadratic and evolutionary programming algorithms using flux balance analysis (FBA), minimization of metabolic adjustment (MOMA), and OptGene, respectively were applied as well as phenotypic behavior and improved balhimycin production were simulated. The A. balhimycina model shows a good agreement between in silico data and experimental data and also identifies key reactions associated with increased balhimycin production. The reconstruction of the genome‐scale metabolic model of A. balhimycina serves as a basis for physiological characterization. The model allows a rational design of engineering strategies for increasing balhimycin production in A. balhimycina and glycopeptide production in general. Biotechnol. Bioeng. 2012; 109:1798–1807. © 2012 Wiley Periodicals, Inc.
Macro‐scale topology optimization for controlling internal shear stress in a porous scaffold bioreactor
Authors: Youssef K. , Mack J.J. , Iruela‐Arispe M.L. , Bouchard L.‐S. 
Published: January 2012

AbstractShear stress is an important physical factor that regulates proliferation, migration, and morphogenesis. In particular, the homeostasis of blood vessels is dependent on shear stress. To mimic this process ex vivo, efforts have been made to seed scaffolds with vascular and other cell types in the presence of growth factors and under pulsatile flow conditions. However, the resulting bioreactors lack information on shear stress and flow distributions within the scaffold. Consequently, it is difficult to interpret the effects of shear stress on cell function. Such knowledge would enable researchers to improve upon cell culture protocols. Recent work has focused on optimizing the microstructural parameters of the scaffold to fine tune the shear stress. In this study, we have adopted a different approach whereby flows are redirected throughout the bioreactor along channels patterned in the porous scaffold to yield shear stress distributions that are optimized for uniformity centered on a target value. A topology optimization algorithm coupled to computational fluid dynamics simulations was devised to this end. The channel topology in the porous scaffold was varied using a combination of genetic algorithm and fuzzy logic. The method is validated by experiments using magnetic resonance imaging readouts of the flow field. Biotechnol. Bioeng. 2012; 109:1844–1854. © 2012 Wiley Periodicals, Inc.
The granule size distribution in an anammox‐based granular sludge reactor affects the conversion—Implications for modeling
Authors: Volcke E.I.P. , Picioreanu C. , De Baets B. , van Loosdrecht M.C.M. 
Published: January 2012

AbstractMathematical models are useful tools to optimize the performance of granular sludge reactors. In these models, typically a uniform granule size is assumed for the whole reactor, even though in reality the granules follow a size distribution and the granule size as such affects the process performance. This study assesses the effect of the granule size distribution on the performance of a granular sludge reactor in which autotrophic nitrogen removal is realized through one‐stage partial nitritation–anammox. A comparison is made between different approaches to deal with particle size distributions in one‐dimensional biofilm models, from the use of a single characteristic diameter to applying a multiple compartment model. The results show a clear impact on the conversion efficiency of the way in which particle size distribution is modeled, resulting from the effect of the granule size on the competition between nitrite oxidizing and anammox bacteria and from the interaction between granules of different sizes in terms of the exchange of solutes. Whereas the use of a uniform granule size is sufficient in case only the overall reactor behavior needs to be assessed, taking into account the detailed granule size distribution is required to study the solute exchange between particles of different sizes. For the latter purpose, the application of the widespread software package Aquasim is limited and the development of dedicated software applications is required. Biotechnol. Bioeng. 2012; 109:1629–1636. © 2012 Wiley Periodicals, Inc.
Expression of recombinant green fluorescent protein in Bacillus methanolicus
Authors: Nilasari Dewi , Dover Nir , Rech Sabine , Komives Claire 
Published: January 2012

AbstractMicrobial biocatalysts are used in a wide range of industries to produce large scale quantities of proteins, amino acids, and commodity chemicals. While the majority of these processes use glucose or other low‐cost sugars as the substrate, Bacillus methanolicus is one example of a biocatalyst that has shown sustained growth on methanol as a carbon source at elevated temperature (50–53°C optimum) resulting in reduced feed and utility costs. Specifically, the complete chemical process enabled by this approach takes methane from natural gas, and following a low‐cost conversion to methanol, can be used for the production of high value products. In this study, production of recombinant green fluorescent protein (GFPuv) by B. methanolicus is explored. A plasmid was constructed that incorporates the methanol dehydrogenase (mdh) promoter of B. methanolicus MGA3 together with the GFPuv gene. The plasmid, pNW33N, was shown to be effective for expression in other Bacillus strains, although not previously in B. methanolicus. A published electroporation protocol for transformation of B. methanolicus was modified to result in expression of GFP using plasmid pNW33N‐mdh‐GFPuv (pNmG). Transformation was confirmed by both agarose gel electrophoresis and by observation of green fluorescence under UV light exposure. The mass yield of cells and protein were measured in shake flask experiments. The optimum concentration of methanol for protein production was found to be at 200 mM. Higher concentrations than 200 mM resulted in slightly higher biomass production but lower amounts of recombinant protein. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
A New Benzoylphloroglucinol Derivative with an Adamantyl Skeleton and Other Constituents from Garcinia multiflora: Effects on Neutrophil Pro‐Inflammatory Responses
Authors: Ting Chia‐Wei , Hwang Tsong‐Long , Chen Ih‐Sheng , Yen Ming‐Hong , Chen Jih‐Jung 
Published: January 2012

AbstractA novel benzoylphloroglucinol derivative, garcimultiflorone D (1), with an unusual adamantyl‐caged skeleton was isolated from the fruits of Garcinia multiflora, together with four known compounds. The structure of 1 was determined through extensive 1D/2D‐NMR and mass‐spectrometric analyses. Garcimultiflorone D (1) exhibited inhibitory activities with IC50 values of 7.21±1.07 and 6.01±0.37 μg/ml against fMLP/CB‐induced superoxide anion generation and elastase release, respectively.
Synthesis and Antidiabetic Activity of 5,7‐Dihydroxyflavonoids and Analogs
Authors: Chang Liu‐Shuan , Li Chun‐Bao , Qin Nan , Jin Mei‐Na , Duan Hong‐Quan 
Published: January 2012

AbstractIn a study to evaluate the structural elements essential for the antidiabetic activity of flavonoids, we synthesized two series of flavonoids, 5,7‐dihydroxyflavanones and 5,7‐dihydroxyflavones. In a screening for potential antidiabetic activity, most of the flavonoids showed a remarkable in vitro activity, and compounds 1f, 2d, and 3c were significantly more effective than the positive control, metformin. The biological activity was mainly affected by structural modification at the ring B moiety of the flavonoid skeleton. The results suggest that 5,7‐dihydroxyflavonoids can be considered as promising candidates in the development of new antidiabetic lead compounds.