bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of organoclay in an immiscible poly(ethylene terephtalate) waste/poly(methyl methacrylate) blend
Authors: Kerboua N. , Cinausero N. , Sadoun T. , Lopez‐Cuesta J. M. 
Published: March 2010

AbstractBlends of organically modified montmorillonite (OMMT) with poly(ethylene terephtalate) (PET) waste and poly(methyl methacrylate) (PMMA) were prepared by melt mixing. The morphology of PET/PMMA nanocomposites with different OMMT contents was characterized by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The nonisothermal crystallization temperatures of nanocomposites were also examined by DSC. TEM observations and XRD patterns revealed that silicate layers were intercalated and well dispersed in the blend. Nanocomposites displayed better mechanical properties when compared with the unfilled blend. DMA analyses also showed efficient mixing of the two immiscible polymers and changes in glass transition temperature with the presence of OMMT. DSC analysis showed an enhancement in crystallization rate of nanocomposites and a decrease in cristallinity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of biodegradable and biocompatible ABC triblock copolymers
Authors: He Xiaohua , Zhong Liang , Wang Kai , Luo Shufang , Xie Meiran 
Published: March 2010

AbstractA facile approach is offered to synthesize well‐defined amphiphilic ABC triblock copolymers composed of poly(ethylene glycol) monomethyl ether (MPEO) as A block, poly(L‐lysine) (PLLys) as B block, and poly(ε‐caprolactone) (PCL) as C block by a combination of ring‐opening polymerization (ROP) and click reactions. The propargyl‐terminated poly(Z‐L‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) diblock copolymers were synthesized via the ring‐opening polymerization of Nε‐carbobenzoxy‐L‐lysine N‐carboxyanhydride (Z‐L‐Lys NCA) in DMF at room temperature using propargyl amine as an initiator and the resulting amino‐terminated poly(Z‐L‐lysine) then used in situ as a macroinitiator for the polymerization of ε‐caprolactone in the presence of stannous octoate as a catalyst. The triblock copolymers poly(ethylene glycol) monomethyl ether –block‐poly(Z‐L‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) were synthesized via the click reaction of the propargyl‐terminated PzLLys‐PCL and azido‐terminated poly(ethylene glycol) monomethyl ether (PEO‐N3) in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. After the removal of Z groups of L‐lysine units, amphiphilic and biocompatible ABC triblock copolymers MPEO‐PLLys‐PCL were obtained. The structural characteristics of these ABC triblock copolymers and corresponding precursors were characterized by NMR, IR, and GPC. These results showed the click reaction was highly effective. Therefore, a facile approach is offered to synthesize amphiphilic and biocompatible ABC triblock copolymers consisting of polyether, polypeptide and polyester. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Silk‐inspired polyurethane containing GlyAlaGlyAla tetrapeptide. I. Synthesis and primary structure
Authors: Liu Hongtao , Xu Weilin , Zhao Sanping , Huang Jingjing , Yang Hongjun , Wang Yunli , Ouyang Chenxi 
Published: March 2010

AbstractBiomedical polyurethane (PU) and silk fibroin have similar molecular architecture in their primary and aggregate structure, both of which have imido bonds and microphase separation, and they have been employed as scaffold materials for biomedical applications. As the featured peptide sequence of silkworm silk protein, GlyAlaGlyAla (GAGA) tetrapeptide was synthesized by using traditional liquid‐phase peptide synthesis method with Boc‐protected alanine and glycine as starting materials, and was transformed to its derivative with two end‐amido groups. The derivative was incorporated into the backbone of the classical synthetic copolyurethane as a chain extender to form a silk‐inspired polyurethane. Elemental analysis showed the nitrogen content in the silk‐inspired PU was higher than that in the butanediol‐extended PU but lower than the theoretical value, indicating the chain extender containing GAGA was partially incorporated into the PU chain. The results from 1H‐nuclear magnetic resonance, Fourier transform infrared spectra, Raman scattering spectra and pyrolysis‐gas chromatography/mass spectrometry qualitatively identified the primary structure of the silk‐inspired polyurethane. This concept and strategy may allow the fabrication of a new class of thermoplastic polyurethane elastomer to mimic the structure and properties of silk fibers if in fiber form, which combines traditional synthetic polymer chains with peptide sequences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of manganese oxide–polyethylene oxide hybrid nanofibers through in situ electrospinning
Authors: Madani Mohammad , Sharifi‐Sanjani Naser , Khoee Sepideh , Hasan‐Kaviar Ahmad , Kazemi Abbass 
Published: March 2010

AbstractManganese oxide nanoparticles–polyethylene oxide nanofibers as organic–inorganic hybrid were prepared via in situ electrospinning. Thus, electrospinning of polyethylene oxide solution with different manganese chloride concentration was carried out in gaseous ammonia atmosphere containing oxygen. The reaction of manganese chloride with ammonia produces manganese hydroxide, and then oxygen in the reaction media reacts with manganese hydroxide to yield manganese oxide. These two reactions occur during fiber formation. Transmission electron microscopy and scanning electron microscopy showed that manganese oxide (MnO2) nanoparticles were formed on the produced nanofibers of 100–600 nm in diameter. The existence of the formed MnO2 was also proved by X‐ray diffraction analysis, and it showed that the λ‐MnO2 nanoparticles were produced. Differential scanning calorimetry (DSC) analysis was used to determine the melting point and to calculate the crystallinity of the produced hybrid nanofibers. The DSC and thermogravimetric analysis results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Miscibility studies on a copolyester of bisphenol‐A with terephthalic and isophthalic acids/bisphenol‐A polycarbonate blends
Authors: Sakar Dolunay , Cakar Fatih , Cankurtaran Ozlem , Karaman Ferdane 
Published: March 2010

AbstractThe miscibility behavior of the blends of a copolyester of bisphenol‐A with terephthalic and isophthalic acids (PAr) and a bisphenol‐A polycarbonate (PC) was studied in dilute chloroform solutions at 25°C. The intrinsic viscosity and Huggins' parameter of the binary mixtures were determined from the intercept and slope of the linear straight line between specific viscosity and the overall polymer concentration at the studied compositions. From experimental results of the intrinsic viscosities of the mixtures, some miscibility parameters Δb, Δb′, (Δb)G, Δ[η], α, and β were obtained by applying the criteria proposed by the research groups Krigbaum and Wall, Catsiff and Hewett, Garcia et al., Sun et al. and Jiang and Han, respectively. The miscibility of mixtures was also studied by using differential scanning calorimetry and fourier transform infrared spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
An effort based analysis of the paradoxical effects of incentives on decision‐aided performance
Authors: Samuels Janet A. , Whitecotton Stacey M. 
Published: March 2010

AbstractThis study examines the effect of incentives on decision‐aided performance. In particular, the study provides further insight into whether, when, and how incentives affect task performance in the presence of decision aids by (1) replicating previous research showing the negative effects of incentives on performance; (2) investigating whether this effect generalizes to a more realistic scenario in which decision makers have access to additional contextual information not captured by the decision aid; and (3) applying an effort‐based framework to explain the link between incentives and performance. In contrast to the findings of prior research, our study shows that incentives do not necessarily decrease performance in the presence of decision aids. Rather, we demonstrate that the effect of incentives on decision‐aided performance depends on other contextual factors such as the absence or presence of additional contextual information. By further specifying the conditions under which incentives result in increases or decreases to decision‐aided task performance, our results have implications for both future research and the design of incentive systems in practice. Copyright © 2010 John Wiley & Sons, Ltd.
New milliliter‐scale stirred tank bioreactors for the cultivation of mycelium forming microorganisms
Authors: Hortsch Ralf , Stratmann Ansgar , Weuster‐Botz Dirk 
Published: March 2010

AbstractA novel milliliter‐scale stirred tank bioreactor was developed for the cultivation of mycelium forming microorganisms on a 10 milliliter‐scale. A newly designed one‐sided paddle impeller is driven magnetically and rotates freely on an axis in an unbaffled reaction vessel made of polystyrene. A rotating lamella is formed which spreads out along the reactor wall. Thus an enhanced surface‐to‐volume ratio of the liquid phase is generated where oxygen is introduced via surface aeration. Volumetric oxygen transfer coefficients (kLa) > 0.15 s−1 were measured. The fast moving liquid lamella efficiently prevents wall growth and foaming. Mean power consumption and maximum local energy dissipation were measured as function of operating conditions in the milliliter‐scale stirred tank bioreactor (V = 10 mL) and compared to a standard laboratory‐scale stirred tank bioreactor with six‐bladed Rushton turbines (V = 2,000 mL). Mean power consumption increases with increasing impeller speed and shows the same characteristics and values on both scales. The maximum local energy dissipation of the milliliter‐scale stirred tank bioreactor was reduced compared to the laboratory‐scale at the same mean volumetric power input. Hence the milliliter impeller distributes power more uniformly in the reaction medium. Based on these data a reliable and robust scale‐up of fermentation processes is possible. This was demonstrated with the cultivation of the actinomycete Streptomyces tendae on both scales. It was shown that the process performances were equivalent with regard to biomass concentration, mannitol consumption and production of the pharmaceutical relevant fungicide nikkomycin Z up to a process time of 120 h. A high parallel reproducibility was observed on the milliliter‐scale (standard deviation < 8%) with up to 48 stirred tank bioreactors operated in a magnetic inductive drive. Rheological behavior of the culture broth was measured and showed a highly viscous shear‐thinning non‐Newtonian behavior. The newly developed one‐sided paddle impellers operated in unbaffled reactors on a 10 milliliter‐scale with a magnetic inductive drive for up to 48 parallel bioreactors allows for the first time the parallel bioprocess development with mycelium forming microorganisms. This is especially important since these kinds of cultivations normally exhibit process times of 100 h and more. Thus the operation of parallel stirred tank reactors will have the potential to reduce process development times drastically. Biotechnol. Bioeng. 2010; 106: 443–451. © 2010 Wiley Periodicals, Inc.
Adventures in time and space: Nonlinearity and complexity of cytokine effects on stem cell fate decisions
Authors: Audet Julie 
Published: March 2010

AbstractCytokines are central factors in the control of stem cell fate decisions and, as such, they are invaluable to those interested in the manipulation of stem and progenitor cells for clinical or research purposes. In their in vivo niches or in optimized cultures, stem cells are exposed to multiple cytokines, matrix proteins and other cell types that provide individual and combinatorial signals that influence their self‐renewal, proliferation and differentiation. Although the individual effects of cytokines are well‐characterized in terms of increases or decreases in stem cell expansion or in the production of specific cell lineages, their interactions are often overlooked. Factorial design experiments in association with multiple linear regression is a powerful multivariate approach to derive response‐surface models and to obtain a quantitative understanding of cytokine dose and interactions effects. On the other hand, cytokine interactions detected in stem cell processes can be difficult to interpret due to the fact that the cell populations examined are often heterogeneous, that cytokines can exhibit pleiotropy and redundancy and that they can also be endogenously produced. This perspective piece presents a list of possible biological mechanisms that can give rise to positive and negative two‐way factor interactions in the context of in vivo and in vitro stem cell‐based processes. These interpretations are based on insights provided by recent studies examining intra‐ and extra‐cellular signaling pathways in adult and embryonic stem cells. Cytokine interactions have been classified according to four main types of molecular and cellular mechanisms: (i) interactions due to co‐signaling; (ii) interactions due to sequential actions; (iii) interactions due to high‐dose saturation and inhibition; and (iv) interactions due to intercellular signaling networks. For each mechanism, possible patterns of regression coefficients corresponding to the cytokine main effects, quadratic effects and two‐way interactions effects are provided. Finally, directions for future mechanistic studies are presented. Biotechnol. Bioeng. 2010;106: 173–182. © 2010 Wiley Periodicals, Inc.
Effect of chloride on ferrous iron oxidation by a Leptospirillum ferriphilum‐dominated chemostat culture
Authors: Gahan Chandra Sekhar , Sundkvist Jan‐Eric , Dopson Mark , Sandström Åke 
Published: March 2010

AbstractBiomining is the use of microorganisms to catalyze metal extraction from sulfide ores. However, the available water in some biomining environments has high chloride concentrations and therefore, chloride toxicity to ferrous oxidizing microorganisms has been investigated. Batch biooxidation of Fe2+ by a Leptospirillum ferriphilum‐dominated culture was completely inhibited by 12 g L−1 chloride. In addition, the effects of chloride on oxidation kinetics in a Fe2+ limited chemostat were studied. Results from the chemostat modeling suggest that the chloride toxicity was attributed to affects on the Fe2+ oxidation system, pH homeostasis, and lowering of the proton motive force. Modeling showed a decrease in the maximum specific growth rate (µmax) and an increase in the substrate constant (Ks) with increasing chloride concentrations, indicating an effect on the Fe2+ oxidation system. The model proposes a lowered maintenance activity when the media was fed with 2–3 g L−1 chloride with a concomitant drastic decrease in the true yield (Ytrue). This model helps to understand the influence of chloride on Fe2+ biooxidation kinetics. Biotechnol. Bioeng. 2010; 106: 422–431. © 2010 Wiley Periodicals, Inc.
Motif‐based search for a novel fructosyl peptide oxidase from genome databases
Authors: Kim Seungsu , Ferri Stefano , Tsugawa Wakako , Mori Kazushige , Sode Koji 
Published: March 2010

AbstractThe measurement of glycated hemoglobin A1c (HbA1c) has important implications for diagnosis of diabetes and assessment of treatment effectiveness. We proposed specific sequence motifs to identify enzymes that oxidize glycated compounds from genome database searches. The gene encoding a putative fructosyl amino acid oxidase was found in the Phaeosphaeria nodorum SN15 genome and successfully expressed in Escherichia coli. The recombinant protein (XP_001798711) was confirmed to be a novel fructosyl peptide oxidase (FPOX) with high specificity for α‐glycated compounds, such as HbA1c model compounds fructosyl‐αN‐valine (f‐αVal) and fructosyl‐αN‐valyl‐histidine (f‐αVal‐His). Unlike previously reported FPOXs, the P. nodorum FPOX has a Km value for f‐αVal‐His (0.185 mM) that is considerably lower than that for f‐αVal (0.458 mM). Based on amino acid sequence alignment, three dimensional structural modeling, and site‐directed mutagenesis, Gly60 was found to be a determining residue for the activity towards f‐αVal‐His. A flexible surface loop region was also found to likely play an important role in accepting f‐αVal‐His. Biotechnol. Bioeng. 2010; 106: 358–366. © 2010 Wiley Periodicals, Inc.
Scaling‐up of complex whole‐cell bioconversions in conventional and non‐conventional media
Authors: Marques Marco P.C. , de Carvalho Carla C.C.R. , Cabral Joaquim M.S. , Fernandes Pedro 
Published: March 2010

AbstractThe use of whole cells is becoming a more common approach in pharmaceutical and agrochemical industries in order to obtain pure compounds with fewer production steps, higher yields, and cleaner processes, as compared to those achieved with traditional strategies. Whole cells are often used as enzymes pools, in particular when multi‐step reactions and/or co‐factor regeneration are envisaged. Nonetheless, published information on the scale‐up of such systems both in aqueous and in two‐phase aqueous–organic systems is relatively scarce. The present work aims to evaluate suitable scale‐up criteria in conventional and non‐conventional medium for a whole‐cell bioconversion that uses resting cells of Mycobacterium sp. NRRL B‐3805 to cleave the side chain of β‐sitosterol, a poorly water‐soluble substrate. The experiments were performed in 24‐well microtiter plates and in 250 mL shaken flasks as orbital stirred systems, and in 300 mL stirred tanks as mechanically stirred systems. Results show that productivity yields were similar in all scales tested, when maintaining oxygen mass transfer coefficients constant in aqueous systems, or when maintaining constant volumetric power consumption in aqueous–organic two‐phase systems. Biotechnol. Bioeng. 2010;106: 619–626. © 2010 Wiley Periodicals, Inc.
Characterization of a whole‐cell catalyst co‐expressing glycerol dehydrogenase and glucose dehydrogenase and its application in the synthesis of L‐glyceraldehyde
Authors: Richter Nina , Neumann Markus , Liese Andreas , Wohlgemuth Roland , Weckbecker Andrea , Eggert Thorsten , Hummel Werner 
Published: March 2010

AbstractA whole‐cell catalyst using Escherichia coli BL21(DE3) as a host, co‐expressing glycerol dehydrogenase (GlyDH) from Gluconobacter oxydans and glucose dehydrogenase (GDH) from Bacillus subtilis for cofactor regeneration, has been successfully constructed and used for the reduction of aliphatic aldehydes, such as hexanal or glyceraldehyde to the corresponding alcohols. This catalyst was characterized in terms of growth conditions, temperature and pH dependency, and regarding the influence of external cofactor and permeabilization. In the case of external cofactor addition we found a 4.6‐fold increase in reaction rate caused by the addition of 1 mM NADP+. Due to the fact that pH and temperature are also factors which may affect the reaction rate, their effect on the whole‐cell catalyst was studied as well. Comparative studies between the whole‐cell catalyst and the cell‐free system were investigated. Furthermore, the successful application of the whole‐cell catalyst in repetitive batch conversions could be demonstrated in the present study. Since the GlyDH was recently characterized and successfully applied in the kinetic resolution of racemic glyceraldehyde, we were now able to transfer and establish the process to a whole‐cell system, which facilitated the access to L‐glyceraldehyde in high enantioselectivity at 54% conversion. All in all, the whole‐cell catalyst shows several advantages over the cell‐free system like a higher thermal, a similar operational stability and the ability to recycle the catalyst without any loss‐of‐activity. The results obtained making the described whole‐cell catalyst an improved catalyst for a more efficient production of enantiopure L‐glyceraldehyde. Biotechnol. Bioeng. 2010;106: 541–552. © 2010 Wiley Periodicals, Inc.
Fabrication of Fluorescent Silica Nanoparticles Hybridized with AIE Luminogens and Exploration of Their Applications as Nanobiosensors in Intracellular Imaging
Authors: Faisal Mahtab , Hong Yuning , Liu Jianzhao , Yu Yong , Lam Jacky W. Y. , Qin Anjun , Lu Ping , Tang Ben Zhong 
Published: March 2010

AbstractHighly emissive inorganic–organic nanoparticles with core–shell structures are fabricated by a one‐pot, surfactant‐free hybridization process. The surfactant‐free sol–gel reactions of tetraphenylethene‐ (TPE) and silole‐functionalized siloxanes followed by reactions with tetraethoxysilane afford fluorescent silica nanoparticles FSNP‐1 and FSNP‐2, respectively. The FSNPs are uniformly sized, surface‐charged and colloidally stable. The diameters of the FSNPs are tunable in the range of 45–295 nm by changing the reaction conditions. Whereas their TPE and silole precursors are non‐emissive, the FSNPs strongly emit in the visible vision, as a result of the novel aggregation‐induced emission (AIE) characteristics of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs pose no toxicity to living cells and can be utilized to selectively image cytoplasm of HeLa cells.
Nanostructure Copper‐exchanged ZSM‐5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)
Authors: Hosseini S. Ali , Niaei Aligholi , Salari Dariush , Aghazadeh Faezeh 
Published: March 2010

AbstractGas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM‐5 catalysts under atmospheric pressure. Nanostructure of ZSM‐5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM‐5 was determined using EDX, ICP‐AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu‐ZSM‐5 catalysts than those of parent ZSM‐5 and HZSM‐5, which revealed catalytic role of copper ions in the Cu‐ZSM‐5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu‐ZSM‐5 catalysts. Furthermore, the catalytic activity of Cu‐ZSM‐5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co‐feed had an inhibitive effect on conversion of organic compounds over the Cu‐ZSM‐5 catalysts.
A Thermodynamic Study on the Binding of Human Serum Albumin with Lanthanum Ion
Authors: Rezaei Behbehani G. , Divsalar A. , Saboury A. A. , Faridbod F. , Ganjali M. R. 
Published: March 2010

AbstractThermodynamics of the interaction between lanthanum(III) ion, La3+, and human serum albumin (HSA), was investigated at pH 7.0 and 300 K in Tris‐HCl buffer by isothermal titration calorimetry. A solvation model was used to reproduce the enthalpies of HSA interaction with La3+. The solvation parameters recovered from our new model were attributed to the structural change of HSA and its biological activity. The interaction of HSA with La3+ showed a set of two binding sites with negative cooperativity.