Search

Understanding the activity of biomolecules in cosolvent systems is important for catalysis, separation and developing biosensors. The majority of previously studied solvents are either phase separated with water or miscible with water. Butanol was recently used to extract water for the conjugation of DNA to gold nanoparticles. In this work, the effect of butanol on the activity of a few RNA-cleaving DNAzymes was studied. A 130-fold improvement in sensitivity for the Na+ -specific EtNa DNAzyme was observed, and butanol also improved the activity of another Na+ -specific DNAzyme, NaA43T by a few folds. However, when divalent metal ions were used for both EtNa and 17E DNAzymes, the activity was inhibited. A main driven force for enhanced DNAzyme activity is the concentration effect due to butanol dehydration. This study provides insights into the interplay between DNA, metal ions and organic solvents, and such an understanding might be useful for developing sensitive biosensors.

INTRODUCTION Cutin is a biopolyester involved in waterproofing aerial plant organs, including leaves. Cutin quantification and compositional profiling require depolymerisation, namely by methanolysis, but specific protocols are not available. OBJECTIVES Investigate how different methanolysis conditions regarding catalyst concentration effect cutin depolymerisation and monomer release, to better define protocols for cutin content determination and composition profiling. MATERIAL AND METHODS Cork oak (Quercus suber) dewaxed leaves were reacted with five sodium methoxide (NaOMe) concentrations. Extracts were analysed: glycerol by high-performance liquid chromatography (HPLC) and long-chain lipids by gas chromatography-mass spectrometry (GC-MS). RESULTS Cutin was completely removed by 3% NaOMe (8.4% of dewaxed leaves), while mild 0.1% and 0.01% NaOMe methanolysis only depolymerised 14% of total cutin. Reactivity of cutin ester bonds is not homogeneous and glyceridic ester bonds are more easily cleaved, releasing the existing glycerol already under the mildest conditions (0.53% with 0.01% NaOMe and 0.41% with 3% NaOMe). The composition of cutin extracts varies with depolymerisation extent, with easier release of alkanoic acids and alkanols, respectively, 34.9% and 8.8% of total monomers at 0.1% NaOMe, while ω-hydroxyacids (49.3% of total monomers) and α,ω-diacids (9.0% of the monomers) are solubilised under more intensive reactive conditions. CONCLUSION Cutin of Quercus suber leaves is confirmed as a glyceridic polyester of ω-hydroxyacids and alkanoic acids, with minor content of α,ω-diacids, and including coumarate moieties. The protocol for the determination of cutin content and compositional profiling was established regarding catalyst concentration. The molar composition of cutin suggests a macromolecular assembly based on glycerol linked to lipid oligomeric chains with moderate cross-linking.

The study of CO2 electrochemical reduction to useful compounds using bare or modified BDD electrode attracts numerous attentions. Meanwhile, the efficiency of products obtained from CO2 electrochemical reduction is known to be determined by the electrode material and the electrolyte. Formic acid as main product and CO as a minor product, have also been known on the CO2 reduction using BDD electrode. Recently, we reported the successful improvement of CO production from the reduction of CO2 by decorating the surface of BDD electrode with palladium particles. Following this, herein, we present further investigation on electrolyte dependence, including cation and anion dependence and also concentration effect in order to understand deeply the CO2 reduction on surface of palladium modified BDD electrode. The results suggest the use of NaCl and KCl as a catholyte for optimum performance, in addition to the improvement of CO2 reduction product in higher electrolyte concentration.

The concentration effect of ionic surfactants was investigated on the Briggs-Rauscher oscillatory reaction in a stirred batch reactor at 25 °C in both the absence and presence of an ionic surfactant. In the presence of the anionic surfactant, the induction period and the oscillation period increase markedly, and the amplitude of oscillations decreases ith increasing concnetration of sodium dodecylsulphate. These effects have been observed when the concentraion of surfactant is much higher than its critical micelle concentration. Another effect on IP and OP has been observed in the presence of cationic and zwitterionic surfactants. A decrease in IP lerads to its extinction at a ceratin concentration and at the same time, chemical oscillations divide into two series of chemical oscillations. TBAH does not have a major influence on IP and OP of the BR oscillatory reaction. The observed effects are explained in terms of micellar catalysis or inhibition in different extens of individual reactants solubilisation respectively.

Field desorption mass spectrometry under ambient conditions is used to study solution-phase organic reactions in micro-volumes. Reagent solution is transferred onto the microdendrites of the field emitter, and reaction products are examined online by mass spectrometry. Three reactions, hydrazone formation by phenyl hydrazine and indoline-2,3-dione, the Katritzky reaction between a pyrylium salt and anisidine, and the Hantzsch synthesis of 1,4-dihydropyridine, were investigated, and reaction acceleration was observed to different extents. The increase in rate relative to the corresponding bulk reactions is attributed to solvent evaporation (simple concentration effect) and to the increase of surface-to-volume ratio (enhanced interfacial reactions). A distinguishing feature of this method of reaction acceleration, relative to that based on nano electrospray ionization, is the observation of radical cations and the formation of radical cation products. The study also breaks new ground in using field emitters at atmospheric pressure.

The phenomena and mechanism of electrospray modes in nanoscale are investigated from experiments and molecular dynamics simulations. It is found that the ionic concentration plays a crucial role in determining the dripping or the jetting modes in a nanoscale electrospray system. Molecular dynamics simulations uncover that the two modes are caused by the competition between the electric field stress and surface tension, which is similar to the mechanism in a macroscale electrospray system. However, in a nanoscale electrospray system, the two competing forces of the electric field stress and surface tension are more sensitive to the ion distributions than that in a macroscale electrospray system, in which the applied voltage and pressure dominate. With the decrease of the nozzle diameter to nanoscale, the ions not only affect the local electric field stress, but also destroy the hydrogen bonds among water molecules, which lead to that the ion concentration becomes a dominant factor in determining the electrospray modes in nanoscale. The discovery provides a novel method to control nanoscale electrospray modes, which may find potential applications for mass spectrometry, film deposition, and electrohydrodynamic printing.

2D computer simulation revealed that amino acids and weak electrolytes were cationized because of the migration of counter-ion from a BGE zone to a sample zone, which encouraged electrokinetic injection (EKI) of these analytes (by the mobility-boost (MB) effect). To investigate the effects of kinds and concentrations of counter-ions on the MB effect and the analyte amount injected into the capillary, experiments, and 1D computer simulations were performed. When acetate was used as the counter-ion, the LODs (S/N = 3) of l-histidine and creatinine, respectively, reached 0.10 and 0.25 nM because of the concentration effect by transient ITP (tITP). The concentrations of l-histidine and creatinine in human blood plasma obtained using the proposed method were agreed with those obtained using the conventional methods. The proposed method can be applied to the analysis of amino acids and weak bases that have similar pI and pKa to l-histidine and creatinine.

In the present study, a micellar electrokinetic chromatographic method was used to determine the retention factors of hydrophilic monomeric and homodimeric forms of glutathione analogues. Ionic-liquid-based surfactant, 1-tetradecyl-3-methylimidazolium chloride, as well as cetyltrimethylammonium bromide and phosphate buffer (pH 7.4) were employed in the experiments. Since the studied peptides possess a negative charge under physiological conditions, it is expected that the peptides interact with the oppositely charged 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide micelles via hydrophobically assisted electrostatic forces. The dependence of the retention factor on the micellar concentration of 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide is nonlinear and the obtained curves converge to a limiting value. The retention factor values of GSH analogues were in the range of 0.36-2.22 for glutathione analogues and -1.21 to 0.37 for glutathione when 1-tetradecyl-3-methylimidazolium chloride was used. When cetyltrimethylammonium bromide was employed, the retention factor values were in the range of 0.27-2.17 for glutathione analogues and -1.22 to 0.06 for glutathione. If sodium dodecyl sulfate was used, the retention factor values of glutathione analogues with carnosine moiety were in the range of -1.54 to 0.38.

The effect of surfactant concentration on the synthesis of Si nanoparticles (NPs) was studied. Hexyl Si NPs were synthesized using one-pot synthetic methodology with different ratios of SiCl4:HexylSiCl3 (1:1, 1:2, 1:3, 1:6) to observe the effect of surfactant concentration on the size of Si NPs. In Fourier transform infrared spectroscopy analysis, the Si–H stretching band and the characteristic Si–O–Si bands decreased and eventually disappeared with increasing hexyltrichlorosilane concentration. This suggests that the level of oxidation decreased with excess amounts of hexyltrichlorosilane because the surface area of exposed Si NPs without hexyl capping groups was reduced. Results of transmission electron microscopy and particle size analysis showed that the average diameter of hexyl Si NPs increased slightly from low surfactant concentration (SiCl4:HexylSiCl3 = 1:1) to high concentration (1:6). This might be caused due to the relationship between the surfactant concentration effect and the core material part effect of hexyltrichlorosilane. Agglomerated Si NPs were observed and their luminescence bands were not shifted because the Si NPs were capped by alkyl groups to prevent aggregation.

The isothermal crystallization at 20°C of cocoa butter (CB) or milk chocolate (MC) with addition of two different sunflower lecithins and one soy lecithin in different concentrations was investigated by differential scanning calorimetry (DSC), oscillatory rheology and a dynamic experiment. A two-step crystallization process was observed with first formation of an unstable α polymorph followed by a polymorphic transition to β′. In the CB matrix, different measuring techniques led to distinct observations by addition of 1.5% lecithin on a fat base. DSC showed a faster α crystallization with addition of lecithin, while rheology measurements demonstrated the reverse effect. However, both measuring techniques evidenced a faster polymorphic transition to the β′ polymorph in lecithin enriched samples. Between the different lecithins no large differences could be detected by the static measuring techniques, while the dynamic experiment exhibited a clearly lower crystallization rate for lecithin B, which was even lower than the pure CB. A remarkable concentration effect was visible in the CB matrix with in general a reduced effect at higher lecithin concentrations. Finally, a different behavior was observed in the MC matrix compared to the CB matrix, presumably by the interaction of lecithin with sugar. Practical applications: Lecithin is added to chocolate formulations to control the flow properties. The handling and processability of the chocolate is improved by a proper viscosity and the perception of flavor by the consumer is also affected by the viscosity (Beckett, 2009, Industrial chocolate manufacture and use, Blackwell Publishing Ltd, Oxford, United Kingdom, pp. 224–246). The effect of lecithin on the rheology of chocolate has been extensively studied, but the effect of lecithin on the crystallization behavior has received much less attention in literature. This is true despite the fact that the crystallization process determines to a large extent the quality of the end product and the addition of minor components such as lecithin can modify the crystallization behavior. As lecithin is a natural product, different lecithins could demonstrate different effects and even different concentrations could show different behaviors (Smith et al., 2011, J. Am. Oil Chem. Soc. 88, 1085–1101). As such, the addition of lecithin should be optimized in chocolate recipes to compromise between flow properties and crystallization behavior. In this work two sunflower lecithins and one soy lecithin were chemically characterized and subsequently their effect (by addition of 1.5%) on the crystallization behavior of cocoa butter was studied by DSC. Thereafter, the concentration effect was examined by varying the added concentration of lecithin between 1, 1.5, and 2%. By using a cocoa butter and milk chocolate matrix, the matrix effect was investigated. Finally, addition of 1.5% lecithin to cocoa butter was also studied with rheology and a dynamic experiment. In general, we can state that the observed effect depends on the concentration, matrix, and measurement technique used, which explains contradictory results in the literature.

Viscosity, loop tack, peel strength, and shear strength of epoxidized natural rubber (ENR 50)/acrylonitrile-butadiene rubber (NBR)–based pressure-sensitive adhesive were studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin with loading of 40 phr was chosen as the tackifier resin. Toluene and polyethylene terephthalate were used as the solvent and coating substrate, respectively, throughout the experiment. The adhesive was coated on the substrate by using a SHEEN hand coater. Viscosity of the adhesive was determined by a Brookfield Viscometer, whereas the loop tack, peel strength, and shear strength were measured by a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that viscosity increases with zinc oxide concentration owing to the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration. This observation is associated with the effect of varying degrees of wettability of the adhesive on the substrate. Shear strength, however, increases steadily with increasing zinc oxide loading owing to the steady increase in cohesive strength. In all cases, the adhesion properties of adhesives increase with increasing coating thicknesses. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers

Enzymatic wheat gluten hydrolysis at high solid concentrations is advantageous from an environmental and economic point of view. However, increased wheat gluten concentrations result in a concentration effect with a decreased hydrolysis rate at constant enzyme-to-substrate ratios and a decreased maximum attainable degree of hydrolysis (DH%). We here identified the underlying factors causing the concentration effect. Wheat gluten was hydrolyzed at solid concentrations from 4.4% to 70%. The decreased hydrolysis rate was present at all solid concentrations and at any time of the reaction. Mass transfer limitations, enzyme inhibition and water activity were shown to not cause this hydrolysis rate limitation up to 50% solids. However, the hydrolysis rate limitation can be, at least partly, explained by a second-order enzyme inactivation process. Furthermore, mass transfer impeded the hydrolysis above 60% solids. Addition of enzyme after 24 h at high solid concentrations scarcely increased the DH%, suggesting that the maximum attainable DH% decreases at high solid concentrations. Reduced enzyme activities caused by low water activities can explain this DH% limitation. Finally, a possible influence of the plastein reaction on the DH% limitation is discussed.

The concentration effect on a two-dimensional (2D) self-assembly of 4, 4′-dihexadecyloxy-benzophenon (DHB) has been investigated by scanning tunneling microscopy. The self-assembly of DHB at the phenyloctane/graphite interface was concentration dependent. Under low concentration, the DHB molecules were adsorbed intactly on the graphite surface. With the increasing of concentration, one of side chains connecting the conjugated moiety stretched into the liquid phase. The coexistence of two self-assembled structures was observed in a moderate concentration. The result indicated that the van der Waals interactions between the molecules and the graphite lattice were decreasing with the increasing concentration. After the samples were placed in ambient conditions over 24 h, a different self-assembled structure was obtained on the gas/solid interface, in which the DHB molecules were adsorbed on the surface with only one of the side chains. Both the benzophenon core and the other side chain were extended to the gas phase. The results demonstrated that concentration played an important role in forming the 2D molecular self-assembly and provided an efficient approach for the control of the DHB molecular nanostructure. Copyright © 2013 John Wiley & Sons, Ltd.

Three types of arylamine-based benzoxazine resins modified with both condensed-phase and gas-phase action flame re- tardant, i.e. triphenyl phosphate (TPP) at various weight ratios were investigated. From rheological study, it was found that the vis- cosity of benzoxazines/TPP mixtures were significantly lower than that of the neat benzoxazine monomers suggesting flow property enhancement. Furthermore, differential scanning calorimetry results revealed that the onset and the maximum temperatures of the exothermic peak, due to the ring opening polymerization of benzoxazine resins, shifted to lower temperatures with increasing TPP. In addition, all polybenzoxazines possessed relatively high char yield, which increased as the TPP content increased thus enhancing their flame retardancy. The limiting oxygen index values of the flame retarded polybenzoxazines also increased with TPP addition. The maximum flame retardancy of UL94 V-0 class was obtained with an addition of only few percents of TPP in the polybenzoxazines. Flexural strength, flexural modulus, and glass transition temperature of those polybenzoxazines tended to decrease with an addition of TPP mainly due to its plasticizing effect. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1074-1083, 2013

Anemonefishes dominate the marine ornamental aquaculture production and coloration plays an important role in market price of the product. This study examined the effect of dietary esterified astaxanthin concentration and duration on skin coloration in spinecheek anemonefish, Premnas biaculeatus. The chromatophore physiology parameters examined were color, density, and diameter of carotenoid granules. Juveniles of 30 days post hatch (d.p.h.) were fed diets consisting of 23, 214, or 2350 ppm esterified astaxanthin for 115 d and the fish were sampled at 45, 120, and 145 d.p.h. Hue was significantly reduced with increasing time and astaxanthin concentration. Saturation fluctuated over time while luminosity was only affected by time. Carotenoid granule density was similar across the treatments: approximately 0.3 granules/µm2. Significant difference in carotenoid granule size was detected, with larger diameters at the higher astaxanthin treatment. Carotenoid granules showed significantly lower hues, higher saturation, and lower luminosity values for the higher astaxanthin concentration diets. This is indicative of higher concentration of carotenoids in the granules. Diets explicitly imparted different coloration in P. biaculeatus and the manifested color differences in the fish are result of increased carotenoid granule size and increased carotenoid concentration within granules. Astaxanthin concentration of 214 ppm imparts adequate coloration for high market value.

Color manipulation of intense multiluminescence from CaZnOS:Mn2+ has been realized by adjusting Mn2+ concentration. Not only the photoluminescence (PL) of Mn2+ emission from 4T1(4G) to 6A1(6S) shows a red shift from yellow to red with increasing Mn2+ concentration, which is in contrast to the fixed PL emission reported by Hintzen et al. (Chem. Mater., 2009), but also mechanoluminescence (ML) and cathodoluminescence (CL) have a similar variation. More attractively, the brightness of multiluminescence is surprisingly intense for all the CaZnOS:Mn2+ with a large-scale Mn2+ doping (0.1–10 mol %). Based on the investigation of crystal field, various spectral results, and PL lifetimes, the red-shift mechanism of multiluminescence reported here has been proposed to arise from the exchange interaction effect of Mn2+ pairs at higher concentrations. In addition to correcting the previous misunderstanding on the emission of CaZnOS:Mn2+, these findings extend the tunable emission window, opening up new opportunities ...

This work aims to study the effects of date stone flour (DSF) on morphology, thermal, and mechanical properties of polypropylene (PP) composites in the absence and presence of ethylene-butyl acrylate-glycidyl methacrylate (EBAGMA) used as the compatibilizer. DSF was added to the PP matrix at loading rates of 10, 20, 30, and 40 wt %, while the amount of compatibilizer was fixed to the half of the filler content. The study showed through scanning electron microscopy analysis that EBAGMA compatibilizer improved the dispersion and the wettability of DSF in the PP matrix. Thermogravimetric analysis (TGA) indicated a slight decrease in the decomposition temperature at onset (Tonset) for all composite materials compared to PP matrix, whereas the thermal degradation rate was slower. Differential scanning calorimetry (DSC) data revealed that the melting temperature of PP in the composite materials remained almost unchanged. The nucleating effect of DSF was however reduced by the compatibilizer. Furthermore, the incorporation of DSF resulted in the increase of stiffness of the PP composites accompanied by a significant decrease in both the stress and strain at break. The addition of EBAGMA to PP/DSF composites improved significantly the ductility due to the elastomeric effect of EBAGMA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Elastomers are materials used in a large range of industrial and household applications. A common physical-chemical treatment is curing (crosslinking), imparting the rubber mechanical and thermal stability. Elastomers show low thermal conductivity values, and therefore, require complex and high-cost heating methods; thus, the ionizing (accelerated electrons) method shows high interest for the grafting and crosslinking processes. In addition to the lack of environmental impact, reliability, flexibility, and low costs render the radiation technologies especially attractive. The article presents the results concerning trimethylolpropane-trimethacrylate coagent concentration effect, on the mechanical properties of the ethylene-propylene–terpolymer (EPDM) rubber vulcanized by electron beam (EB). Mechanical properties of EB irradiated samples were compared with the dibenzoyl peroxide cured samples. Dependence of mechanical properties on irradiation dose was determined from a dose range of 0 kGy to 200 kGy. Dibenzoyl peroxide vulcanization at 160°C was carried out on the EPDM samples as well. Two types of blends have been analyzed: fillers and nonfillers. The results showed an increase in mechanical properties as a function of increasing polyfunctional monomer level. Also, based on the comparison between EB and dibenzoyl peroxide vulcanization efficiency, the results show that EB irradiation gave the best results. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Plants in arid or semiarid areas often experience simultaneous salt and boron (B) stress. Interactive effects on stress responses have been clearly established, but results are inconsistent and variably indicate antagonistic or synergistic interactions even within the same plant species. In this study, five differently B- and salt-resistant wheat genotypes were grown hydroponically at low and high B supply. The effect of increasing NaCl salinity on plant growth, boron uptake rates, shoot B concentrations, and transpiration was determined under both B regimes. The interactive effect of salt and B was different under low and high B supply. Boron-uptake rates were reduced with increasing salt concentration only under high B supply, and reductions correlated significantly with decreases in leaf area and shoot B concentrations. Under low B supply, however, salt-induced effects on B-uptake rates were variable and not significantly correlated with leaf-area reductions. These results suggest that under high B supply, when B uptake is predominantly passive by diffusion or channel-mediated via aquaporins, transpiration-driven water flow is the dominant factor for B accumulation in arial plant parts. Under low B supply, when a significant portion of B can be taken up via active pathways, transpiration is not the decisive factor for B accumulation. Under these conditions, the salt sensitivity of a genotype is a modifying factor of salt–B interactions, because salt-induced growth inhibition can result in a concentration effect, offset the reduction of B-uptake rates, and result in increased shoot B concentrations. Contradictory reports on the nature of salt–B interactions might in part be related to low levels of B supply chosen as control treatments and concomittant differences in predominant B-uptake pathways.

Preconcentration microfluidic devices are fabricated incorporating straight or convergent-divergent microchannels and hydrogel or Nafion membranes. Sample preconcentration is achieved utilizing concentration-polarization effects. The effects of the microchannel geometry on the preconcentration intensity are systematically examined. It is shown that for the preconcentrator with the straight microchannel, the time required to achieve a satisfactory preconcentration intensity increases with an increasing channel depth. For the convergent-divergent microchannel, the preconcentration intensity increases with a reducing convergent channel width. Comparing the preconcentration performance of the two different microchannel configurations, it is found that for an equivalent width of the main microchannel, the concentration effect in the convergent-divergent microchannel is faster than that in the straight microchannel.

A work was carried out on a solid poly- meric electrolyte system comprising blends of poly (vinyl chloride) and liquid 50% epoxidized natural rubber (LENR50) as a polymer host with LiClO4 as a salt and pre- pared by solution casting technique. In this paper, the main study was the effect of LiClO4 salt concentration on the electrolyte properties. The effect of the salt on the elec- trolyte properties was characterized and analyzed with im- pedance spectroscopy (EIS), X-ray diffraction (XRD), differential scanning calorimeter (DSC), and scanning elec- tron microscopy (SEM). The EIS result showed that highest ionic conductivity was obtained at 30 wt % salt with a value of 2.3 � 10 � 8 Sc m � 1 . The XRD results revealed that the LiClO4 salt was fully complexed within the polymer host as no sharp peaks were observed. However, above 30 wt % of salt, some sharp peaks were observed. This phe- nomenon was caused by the association of ions. Mean- while, DSC analysis showed that Tg increased as the salt content increased. This implied that LiClO4 salt had inter- action with polymer host by forming coordination bond. The morphologies' studies showed that good homogeneity and compatibility of the electrolyte were achieved. Upon the addition of the salt, formation of micropores occurred. It was noted that micropores which aid in mobility of ions in the electrolyte system has increased the ionic conductiv- ity. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 2227- 2233, 2012

Nanocomposites containing carbon nanotubes (CNTs) as nanofillers and poly[ethylene-co-(acrylic acid)] (PEAA) or a polymer miscible mixture of PEAA and poly(2-ethyl-2-oxazoline) (PEOx) as a matrix were prepared by the solution-evaporation method with minimal damage to nanotubes. CNTs were prepared by chemical vapor deposition (CVD) with ethanol as the source of carbon. Raman spectroscopy confirmed the presence of single walled carbon nanotubes (SWNTs). High resolution transmission electron microscopy (HRTEM) showed the formation of multi walled carbon nanotubes (MWNTs). Thermal and mechanical properties of the nanocomposites were studied by analyzing samples containing different amounts of CNTs. The degree of crystallinity (Xc) of the PEAA-based nanocomposite containing a smaller amount of CNTs was larger (Xc = 17.0%) than both the one of pure PEAA (Xc = 14.6 %) and PEAA-based nanocomposite containing higher amounts of CNTs (Xc = 15.0%). The Young's modulus, ultimate stress, deformation at break, and toughness obtained from unidirectional tensile tests of the CNTs (1 wt%)-PEAA nanocomposite were higher than both the one of pure PEAA and CNTs (5 wt%)-PEAA nanocomposite. When a polymer mixture of PEAA/PEOx (containing 80 wt% of PEAA) was used as a matrix, a better mechanical response was also detected for nanocomposite containing 1 wt% CNTs. The nanocomposites containing small amounts of CNTs prepared here have potential to be used as coatings of metal or glass surfaces expecting a better mechanical performance than the one of pure matrix. POLYM. COMPOS., © 2011 Society of Plastics Engineers.

The surface-initiated polymerization protocol developed in part I was used to prepare strong anion-exchange membranes with variable polymer chain graft densities and degrees of polymerization for DNA and virus particle separations. A focus of part II was to evaluate the role of polymer nanolayer architecture on DNA and virus binding. Salmon sperm-DNA (SS-DNA) was used as model nucleic acid to measure the dynamic-binding capacities at 10% breakthrough. The dynamic-binding capacity increases linearly with increasing poly ([2-(methacryloyloxy)ethyl]trimethylammonium chloride) chain density up to the highest chain density used in this study. The new membranes yielded threefold higher SS-DNA-binding capacity (30 mg/mL) than a leading commercial membrane with the same functional group chemistry. Elution of bound DNA yielded a sharp peak, and resulted in a 13-fold increase relative to the feed concentration. This concentration effect further demonstrates the highly favorable transport properties of the newly designed Q-type membranes. However, unlike findings in part I on protein binding, SS-DNA binding was not fully reversible. Minute virus of mice (MVM) was used as model virus to evaluate the virus clearance performance of newly designed Q-type membranes. Log reduction of virus (LRV) of MVM increased with increasing polymer chain density. Membranes exhibited >4.5 LRV for the given MVM impurity load and may be capable of higher LRV values, as the MVM concentration in the flow-through fraction of these samples was below the limit of detection of the assay. Biotechnol. Bioeng. 2011;108: 2654–2660. © 2011 Wiley Periodicals, Inc.

Bacterial polyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) containing 5 mol% 4HB was composited with different calcium carbonate (CaCO3) fillers. The effect of CaCO3 contents on thermal properties, mechanical property, and crystallization kinetics was evaluated. The thermal stability of P3/4HB was reduced by mixing with CaCO3 particles. With increasing CaCO3 content, the elongation at break, tensile strength, and impact strength decrease; however, elastic modulus increases. When P3/4HB with 20 mol% 4HB was added into the P3/4HB/CaCO3 composite, the impact strength were enhanced significantly; however, the elongation at break and tensile strength were only slight to moderate improvements. However, when compared with nano- and light-CaCO3, heavy CaCO3 had the best mechanical properties. The nonisothermal and isothermal crystallization results demonstrated that the crystallization rate of P3/4HB was reduced and the highest crystallinity was obtained for all kinds of CaCO3 fillers at 40 phr content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Stripped corn oils with added tocopherols and tocotrienols, at concentrations between 100 and 5,000 ppm, were used to evaluate antioxidant activity of these tocol compounds. The formation of lipid hydroperoxides, measured as peroxide value (PV), was accelerated at 60 °C in the dark for 5 days. Resistance to oxidation as induction period (IP) was also measured using an oxidative stability instrument (OSI) at 100 °C. For PV inhibition, the oils containing α-tocols exhibited decreasing effectiveness with increasing concentration. At day five, samples with 100 ppm α-tocols had the lowest PVs of about 40 mequiv/kg and samples containing 5,000 ppm had the highest values, ranging from 150 to 200 mequiv/kg. At concentrations above 700 ppm of α-tocols, there was an inversion of antioxidative properties as α-tocols promoted lipid oxidation. The opposite concentration effect was observed with δ-tocols and γ-tocotrienol (T3) for which antioxidant effectiveness increased with concentration. OSI-IP hour at 100 °C increased with increasing tocol concentrations for all tocol homologs, although with diminishing effectiveness at greater than 700 ppm. The α-tocols were less effective in extending the IP (~9 h at 5,000 ppm) than the δ-tocols and γ-T3 (13–14 h at 5,000 ppm). Therefore, the antioxidant or prooxidant activities of different tocols are different and the outcomes are different depending on the evaluation methods used.

Chitosan-coated hydroxyapatite (CS-HAp) nanoparticles have been prepared successfully by a modified dropping method. Variations of the final solution pH values, concentration of CS, and CS/HAp volume ratio were examined for their effects on particle size, intensity of surface charge, and tendency of particle formation. The smallest nanoparticles carry a positive charge with 40–50 nm in width and 60–70 nm can be obtained when the CS/HAp ratio is 1 by controlling the final solution pH value at 6.5. The ability of nanoparticles to complex DNA, toxicity of nanoparticles, and the effect of CS-HAp nanoparticle on transferring DNA were also investigated. Transgene expression in HeLa and NIH3T3 cell on the nanoparticles were significant after 2 days. Agarose gel electrophoresis indicated a probable multiple interaction between DNA and CS-HAp while the interaction between DNA appears to be only ionic interaction. No toxic effect on the cells was seen with CS-HAp. Lipofectin, however, was observed to engender marked cytotoxicity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Three types of fullerene (C60)-end-capped poly(4-diphenylaminostyrene) (C60–PDAS) and poly(4-diphenylaminostyrene) (PDAS) blends were prepared to investigate their potential as bipolar polymer semiconductors. The concentration of C60 in the C60–PDAS/PDAS blends strongly affected the hole and electron drift mobility values; the hole drift mobility decreased with an increase in the C60 concentration. However, the electron drift mobility increased with an increase in the C60 concentration. The hole and electron drift mobility values were almost the same for the 1/2 C60–PDAS/PDAS blend; therefore, this polymer blend was thought to be a bipolar polymer semiconductor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

1,2,3,4-Butanetetracarboxylic acid (BTCA) was applied to crosslink amorphous regions of cotton-type rayon fibers via anhydride-mediated esterification for the purpose of a molecular-level control over macroscopic properties. Formation of intrafiber crosslinked structures of the rayon fibers was a facile and efficient method to diminish swelling degree and enhance tensile properties. Crosslinking was conducted under a series of curing temperature and various dosages of BTCA with the presence of sodium hypophosphite as the catalyst for anhydride formation. It was found that crosslinking conditions, both the curing temperature and dosage of the crosslinking agent, made notable impacts on the crosslinking behaviors of the rayon fibers. The dry and wet tensile strength of the rayon fibers were optimized for both the dosage of the crosslinking agent and the curing temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The toughness of three different elastomer-toughened nylon 1010 blends was investigated via standard notched Izod impact test and single edge notched three-point bending test. The toughness of nylon 1010 blends varies much with different elastomer types and components. All three kinds of nylon/elastomer/maleated-elastomer blends showed high impact strength (over 50 kJ m−2) as long as at appropriate blending ratios. With increasing maleated elastomer content, brittle-ductile transition was observed for all three kinds of elastomer-toughened nylon 1010 blends. The number average dispersed particle size (dn) of ethylene-1-octene copolymers or ethylene-vinyl acetate copolymers toughened nylon 1010 blends significantly decreased from over 1 to 0.1 μm with increasing corresponding maleated elastomer content. Investigation on the fracture toughness showed the dissipative energy density gradually increased with decreasing dn, while the limited specific fracture energy increased with increasing dn when dn was below 1 μm and then sharply decreased with further increasing dn. The energy consumed in the outer plastic zone was the main part of the whole energy dissipated during the fracture process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Octa(aminophenyl) polyhedral oligomeric silsesquioxane (OAP-POSS) and boron-containing phenol-formaldehyde resin (BPFR) were synthesized, respectively. The BPFR nanocomposites with different OAP-POSS content (wt%) were prepared, and their properties were characterized. The results show that the thermal degradation process of this nanocomposites can be divided into three stages, and they are all following the first order mechanism. The residual ratio and thermal degradation activation energy Ea of 9 wt% OAP-POSS/BPFR nanocomposites are both better than others and the Ea increase gradually in three stages, which is 93.3, 134.0, and 181.9 kJ mol−1, respectively. Its residual ratio at 900°C is 36.48%. The mechanical loss peak temperature Tp is 228°C for 12 wt% OAP-POSSS/BPFR nanocomposites, which is higher 48°C than pure BPFR. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

The parameters characterizing the interfacial adhesion strength, such as interaction parameter (B) and interfacial adhesion angle (θ), of inorganic particulate-filled polymer composites were analyzed in this paper. On the basis of the previous studies and the research work reported in literature, several expressions for predicting these parameters and the determination methods of these parameters were proposed, and the relationship between the interaction parameter and interfacial adhesion angle was discussed. Then the parameters B and θ were estimated from the experimental measured tensile strength of the several inorganic particulate-filled polypropylene (PP) composites including nanometer calcium carbonate, glass bead and diatomite particles. The results showed that the value of θ was about from 44 to 75 degrees while the value of B was varying from 1.12 to 2.42 of these filled systems under the experimental conditions. Moreover, the value of B decreased roughly linearly with increasing θ for these particulate-filled PP composites.POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Nanocomposites of low-density polyethylene (LDPE)/ethyl vinyl acetate (EVA)/poly(chloroprene) rubber (PCR) blends and multiple walled carbon nanotubes (MWNT) were prepared in different compositions by melt mixing. The nanocomposites were subjected to different radiation doses and efficacy of radiation crosslinking and physic-mechanical characteristics were analyzed in detail. Gel content and crosslinking density increased with dose and with the MWNT fraction in the nanocomposites. The elastic modulus of the nanocomposite increased, while elongation at break exhibited downward trend with radiation dose. Micromechanical modeling of elastic modulus indicated presence of agglomeration in the matrix. Bulk density of the nanocomposites increased with the addition of MWNT while the melt flow index of the nanocomposites decreased sharply. DSC, XRD and TGA investigations revealed the peculiarity of the MWNT led nucleation in LDPE/EVA/PCR/MWNT nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

We study a coarse grained model of cylinder forming diblock copolymers and nano-particles (NPs) mixture confined between Lennard―Jones hard walls. Two models for non-selective interactions between monomers and NPs are applied. In the case of purely repulsive interactions between NPs and monomers (athermal case) strong segregation of NPs at the film surfaces and the formation of droplets of particles inside the copolymer film can be observed. For weakly attractive interactions between NPs and monomers (thermal case) formation of droplets of particles disappears and segregation on the film surfaces depend on temperature. The uptake of NPs by the copolymer film in the thermal case displays a non-monotonic dependence on temperature which can be qualitatively explained by a mean-field model. In both cases of non-selective interactions NPs are preferentially localized at the interface between the microphase domains.

Polyvinylidene fluoride (PVDF)/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared by solution blending method, and the melt viscoelastic behavior of the composites was studied. The results showed that the dispersion of MWCNTs in the matrix and the surface characteristic of MWCNTs had a profound influence on the melt rheological behaviors of the nanocomposites. Generally, the dynamic storage modulus (G′) of the nanocomposites with well dispersed MWCNTs was greatly improved. However, PVDF/MWCNTs-g-OH nanocomposites exhibit more significant solid-like behavior than PVDF/MWCNTs nanocomposites at an MWCNTs loading of 2 wt % or higher, even though the dispersion of MWCNTs-g-OH is poorer than that of virgin MWCNTs owing to the higher interfacial interactions from van der Waals force and hydrogen bonding. In this case, the influence of the interfacial interactions on the melt rheological properties was stronger than the dispersion state. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The effect of NaSCN salt on the spinnability of polyacrylonitrile (PAN) solutions, its resulting morphology, mechanical property, and the flame resistance of the resulting electrospun nanofibers were studied. The intent was to develop a method to produce nanosized carbon fiber precursors with good properties. Electrospun PAN nanofibers from 9.7–9.9 wt% PAN/sodiumthiocyanate (NaSCN) (aq)/Dimethylformamide (DMF) solutions with 1.0–2.9 wt% NaSCN (aq), and 10–15 wt% PAN/DMF solutions without salt exhibited good spinnability and morphology with no beading in the range of applied voltage (18–20 kV) and take-up velocity (9.8–12.3 m/s). The relatively high take-up velocity produced good yarn alignment. The diameter distributions of the PAN nanofibers containing the NaSCN salt were narrower than those of the PAN/DMF nanofibers without the salt. It was determined that the maximum content of salt for production of electrospun PAN nanofibers with good morphology was below 3.8 wt% (40 wt% based on PAN). The salt concentration can positively influence on the narrow diameter distributions of the resulting electrospun fibers. Also, it could be confirmed that the salt effect on mechanical property and flame resistance of electrospun PAN nanofibers. In particular, the elongation of the PAN nanofiber with 2.9 wt% NaSCN (aq) was significantly increased as much as 186% compared with that of 10 wt% PAN nanofiber without the salt. The flame resistance and mechanical properties of the stabilized PAN nanofibers with NaSCN (aq) increased after oxidization process. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.

A series of high-temperature-resistant polyimide/montmorillonite (PI/MMT) nanocomposite foams were prepared by solid blending method. The dispersion of MMT and effects of MMT content on the properties of the PI/MMT nanocomposite foams were investigated. Results indicated that MMT could be exfoliated effectively and dispersed uniformly in the PI matrix by the solid blending method. The introduction of MMT could considerably increase the reduced compressive strength, thermal resistance, and decrease the dielectric constant of the PI/MMT nanocomposite foams. The reduced compressive strength of nanocomposite foams showed a maximum value at the MMT content of 5 wt%, which was 197% higher than that of pure PI foams. It was worth noting that a significant increase in glass-transition temperature (Tg) could be achieved with the increase of MMT content, and the maximum Tg was as high as 436°C at the MMT content of 7 wt%. This study may provide a useful method to prepare PI/MMT nanocomposite foams with improved properties for targeted high-temperature applications. POLYM. ENG. SCI., 2011. ©2011 Society of Plastics Engineers

Composites based on poly(vinyl alcohol) (PVA), acrylamide monomer (AM) and sodium montmorillonite clay (MMT) were prepared, in the form of thin films, by solution casting. The PVA/AM/MMT composites films were then exposed to electron beam irradiation to form crosslinked network structure. The structure-property behavior of PVA/AM/MMT hybrids was demonstrated by x-ray diffraction (XRD), scanning electron microscopy, gel content, color intensity, thermogravimetric analysis (TGA) and swelling behavior in aqueous solutions. The results indicated that the introduction of MMT clay ratio up to 5% decreased the gel content of PVA/AM hydrogels. The color measurements indicated that the introduction of MMT clay ratio up to 5% was shown to affect the color intensity of composite films. It was found that both PVA/AM hydrogels and PVA/AM/MMT composites reached the equilibrium swelling state in water after four hours; however PVA/AM/MMT composites displayed higher swelling than PVA/AM hydrogels. However, the swelling of PVA/AM hydrogels or their composites at the equilibrium state increased with increasing temperature up to 60°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A new type of unsaturated poly(ester-amide) viz maleic anhydride-phthalic anhydride-ethylene glycol-neopentylene glycol-glycin copolymer was prepared by melt polycondensation. The copolymer was characterized by FT-IR, gel permeation chromatography, and thermal gravimetric analysis. The molecular structure of crosslinked unsaturated poly(ester-amide) was determined by wide-angle X-ray diffraction. Hydroxyapatite (n-HA) was used to boost up the new unsaturated poly (ester-amide), the flexural properties of n-HA/unsaturated poly(ester-amide) nanocomposites with different n-HA content were measured. Studies of degradation behavior were carried out in simulated body fluid at pH 7.4 and 37°C, the flexural strength changes and cumulative mass loss of n-HA/ unsaturated poly(ester-amide) nanocomposites were measured at different degradation times. The n-HA/unsaturated poly(ester-amide) nanocomposites was hydrolyzed in 1M NaOH standard solution at room temperature to study the mass loss with different n-HA contents. All the preliminary results suggested that n-HA/unsaturated poly(ester-amide) nanocomposites might be potentially used as a new type of bone fixation material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The present article summarizes an experimental study on the effects of two additives on polypropylene/seaweed (PP/SW) biocomposites by dynamic rheological characterization. Storage and loss moduli as a function of frequency were obtained by small-amplitude shear oscillation tests in parallel-plate mode. Maleic anhydride-grafted polypropylene (MAPP) was found to provide good external lubrication, while CNT masterbatch (CESA) promoted fiber–fiber interaction. Han plot and Cole-Cole plot visibly present the difference between the two interaction mechanisms. A synergistic effect was also observed when MAPP and CESA were simultaneously used in biocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Two types of supramolecular carbon nano- structures, carbon nanospheres (CNS) and multiwalled carbon nanotubes, (MWCNTs) are investigated for their potential as nanofillers in the bioplastic polylactide (PLA). Modification of the surfaces of both carbon nanostructures by covalent attachment of dodecylamine is accomplished and the effects of this compatibilizing functionality are explored. Crystallization kinetics, thermal properties, and mechanical properties are investigated. Addition of a small amount of carbon to the PLA increases the thermal stabil- ity by as much as 20-30 � C. Incorporation of the MWCNT and CNS increases the heat distortion temperature by up to 10 � C. Speed up in crystallization rate is observed for small to intermediate loading levels; however, at higher nanofiller loading, the rate decreases. Functionalized nano- structures are more effective at increasing crystallization rates than unfunctionalized nanostructures. It is concluded that the dodecylamine (DDA) grafted to the carbon surfa- ces aids in dispersing the materials and preventing aggre- gation, thereby providing higher surface area for heterogeneous nucleation of the biopolymer. The resulting materials are composed of the supramolecular carbon nanostructure embedded in a semicrystalline biopolymer matrix. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2029-2038, 2011

Water sorption in hydrogels based on nanocomposites of poly(2-hydroxyethyl acrylate) (PHEA) and silica, prepared by simultaneous polymerization and sol-gel process, were studied gravimetrically over wide ranges of silica content, both below and above the percolation threshold of about 15% wt for the formation of a continuous inorganic network interpenetrated with the organic network. Measurements were performed at room temperature from the vapor phase, both at equilibrium and dynamic, for selected values of water activity αw between 0 and 0.95, and from the liquid phase. In the nanocomposite hydrogels, the overall water uptake from the vapor phase is practically the same as in pure PHEA below the percolation threshold, whereas it is reduced above the percolation threshold, in particular at high αw values where swelling becomes significant. Water clustering sets in at around 14 vol % (10 wt %) of water independently of composition, whereas the mean value of water molecules in a cluster decreases at high silica contents. In immersion experiments water uptake decreases as silica content increases to the percolation threshold of about 15 wt % and is then almost independent of composition. A scheme is proposed, which explains these results in terms of the existence of micelles, where a number of hydrophilic hydroxy groups are linked together, and their disentaglement by immersion into water. Diffusion coefficients of water depend on water content and are reduced on addition of silica above the percolation threshold. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

The effects of particle size and parent polymer characteristics on the mechanical properties, gel fraction, and swelling index of self-crosslinkable poly(n-butyl methacrylate-co-N-methylolacrylamide) films made by two-stage emulsion or microemulsion polymerization in the presence of variable amounts of the chain transfer agent, n-butyl mercaptan, are reported here. In films prepared with latexes made by microemulsion polymerization, the crosslinking degree increased greatly on curing; by contrast, in those made by emulsion polymerization, the crosslinking degree practically did not increase after curing. Stress–strain tests of uncured and cured films indicate that microemulsion-made films are tougher than the emulsion-made films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(ethylene-co-vinyl alcohol) (EVOH)/carbon black (CB) and EVOH/graphite (GP) electro-conductive composites were prepared by saponification of poly(ethylene-co-vinyl acetate) (EVA)/CB and EVA/GP composites in ethanol/KOH solution. The electrical resistivity change and positive temperature coefficient (PTC) behavior of these composites were investigated. The volume resistivity of EVA/CB and EVA/GP composites was decreased with saponification time. It can be observed that EVA/CB10 and EVA/GP05 composites showed a significant reduction in resistivity after saponification for 1 h. With the increase in saponification time, PTC peak temperature of both composites was shifted at a higher temperature. Tensile properties, morphology, and thermal behavior of the prepared composites have been also evaluated using universal test machine, scanning electron microscopy, and differential scanning calorimetry, respectively. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Tris-2,3-dimethyl-hexylamide of trimesic acid (TATA) is an new type of β-nucleating agent for isotactic polypropylene (iPP). The crystallization, melting characteristics, and the supermolecular structure of iPP nucleated with TATA were studied on the samples crystallized under nonisothermal and isothermal conditions. The β-nucleating ability of TATA was rather high even at low concentration. It was established that TATA possessed dual nucleating ability generating samples with mixed (α and β) polymorphic compositions. The β-content showed an maximum value at low concentrations (10–100 ppm) of TATA. The β-content decreased with increasing concentration of TATA in the higher concentration range. The highest β-content (about 80%) was achieved at the crystallization temperature Tc = 110–120°C at low concentration of TATA. The crystallization curves registered at constant cooling rate or under isothermal condition have a single peak in spite of the formation of two polymorphic modifications. The crystallization isotherms cannot be linearized according to the Avrami equation because of simultaneous crystallization of the α-and β-forms, having different nucleation and growth rate. It was also found that the β-content increased with increasing conversion during isothermal crystallization because of the higher growth rate of the β-phase. The β-phase formed in the presence of TATA consist of lamellar crystallites. In the early stage of the crystallization, hedritic structure is formed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Styrene butadiene rubber (SBR) was efficiently cured (crosslinked) by using sulfur to accelerator ratio less than unity. This cured SBR was further compounded with carbon black filler (grade N330) with three different doses i.e., 5, 10, and 20 wt % of filler to form three different filled and crosslinked membranes, i.e., SBR5, SBR10, and SBR20. These filled rubber membranes and one unfilled but efficiently cured membrane, i.e. SBR0, were used for pervaporative removal of pyridine from its mixtures with water. The filled membranes were found to show better selectivity and mechanical properties but lower flux than the unfilled membrane. All of these membranes showed reasonably good range of flux and pyridine selectivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011