bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sequence–Structure–Property Relationships of Recombinant Spider Silk Proteins: Integration of Biopolymer Design, Processing, and Modeling
Authors: Krishnaji Sreevidhya Tarakkad , Bratzel Graham , Kinahan Michelle E. , Kluge Jonathan A. , Staii Cristian , Wong Joyce Y. , Buehler Markus J. , Kaplan David L. 
Published: August 2012

AbstractThe mechanical properties of spider silks drive interest as sources of new materials. However, there remains a lot to learn regarding the relationships between sequence, structure, and mechanical properties. In order to predict the types of sequence–functional relationships, synthesis–characterization–computation are integrated using recombinant spider silk‐like block copolymers. Two designs are studied, both with origins from the spider Nephila clavipes. These proteins are studied both experimentally and in silico to understand the relationships between sequence chemistry, processing, structure, and materials function. Films formed from the two proteins are thoroughly characterized. In parallel, molecular modeling is used to assess the propensity of the two sequences to form β‐sheets or crystalline structures. The results demonstrate that the modeling predicts the structural differences between the two silk‐like polymers and these features can also be related to differences in functional outcomes. With this example of relating sequence design (hydrophobic–hydrophilic domains), experiment (genetic design and synthesis), processing (film and fiber formation) and modeling (predictions of crystallinity), synergy among these methods is demonstrated for predictable material outcomes. This approach offers a robust discovery path when looking towards next generation approaches to targeted materials outcomes.
Mesoporous Protein Particles Through Colloidal CaCO3 Templates
Authors: Schmidt Stephan , Behra Muriel , Uhlig Katja , Madaboosi Narayanan , Hartmann Laura , Duschl Claus , Volodkin Dmitry 
Published: August 2012

AbstractPorous colloidal particles can be tailored using templating techniques to maximize their effectiveness for a wide range of applications, including separation, catalysis, and drug delivery. However, templating usually involves harsh and complex preparation conditions, thereby complicating the fabrication of sensitive bio‐functionalized particles. Here a simple, yet versatile and mild approach us used to create porous protein particles using mesoporous CaCO3 colloids as sacrificial templates. The three‐step preparation procedure involves infiltrating the colloidal templates with the protein by solvent evaporation, protein crosslinking, and removal of CaCO3. Using this method one can obtain porous particles consisting of virtually any protein. To explore the applicability of the particles for various scenarios particles composed of different proteins are fabricated focusing on hemoglobin and trypsin and particle morphology, porosity, mechanical properties, the protein redox state, and enzymatic activity are determined. The results show that the nanoporous template structure is replicated and that the proteins are fully functional. By varying preparation conditions such as crosslinker concentration and protein content the elastic modulus is adjusted in the range of red blood cells. This ensures high deformability upon flow in microchannels and makes the porous protein particles a versatile platform for biomedical applications.
Adding Autonomic Healing Capabilities to Polyethylene Oxide
Authors: Chipara Dorina Magdalena , Flores Maritza , Perez Alma , Puente Nancy , Lozano Karen , Chipara Mircea 
Published: August 2012

AbstractThe addition of autonomic healing (frequently defined as self‐healing) capabilities to a water‐soluble polymer (polyethylene oxide, PEO) is for the first time reported. The self‐healing system consists of urea‐formaldehyde microcapsules filled with dicyclopentadiene and first‐generation Grubbs catalyst, dispersed within polyethylene oxide. Raman spectroscopy, optical microscopy, electron microscopy, and thermogravimetric analysis were used to characterize this autonomic healing system. Self‐healing capabilities were confirmed by mechanical testing (load–displacement, engineering stress–engineering strain, and true stress–true strain dependences) recorded at very slow elongation rates (0.01 mm/s). The testing fate was chosen to allow for the complete consumption of the monomer before fracture (the polymerization kinetics of PEO was estimated from Raman measurements). © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E505–E513, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21296
Effect of Surface Modification on the Properties of a Superfine Down Powder Filled Polypropylene Fiber
Authors: Wu Zhongbo , Wang Luoxin , Gan Houlei , Zou Hantao , Yi Changhai , Xu Weilin 
Published: August 2012

AbstractThe superfine down powder (SDP) was chemically modified using phenyl isocyanate (PI) and octadecyl isocyanate(ODI), respectively. The wetting behavior of water on the SDP surface was observed by the contact angle. The modified and unmodified SDP‐filled polypropylene (PP/SDP) fibers were prepared and characterized by the moisture absorption experiments and thermal and mechanical analysis. The PI‐ and ODI‐modification improved the hydrophobic property of SDP, and the excellent moisture absorption of SDP remained as such. The addition of SDP improved the moisture absorption and thermal stability of the PP fiber. The modification of PI and ODI strengthened the mechanical property of the blend fiber. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E514–E519, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21297
Synthesis and Characterization of pH Responsive Conductive Composites of Poly(acrylic acid‐co‐acrylamide) Impregnated with Polyaniline by Interfacial Polymerization
Authors: Boruah Monalisha , Kalita Amarjyoti , Pokhrel Binod , Dolui Swapan Kumar , Boruah Ratan 
Published: August 2012

AbstractElectrically conducting composite hydrogels of poly(acrylic acid‐co‐acrylamide) and polyaniline were prepared by a simple two‐step synthesis process using an aqueous polymerization technique at room temperature and interfacial polymerization of aniline at a water/organic‐solvent interface. The structures of the hydrogels so prepared were confirmed using Fourier transform infrared, UV–vis, X‐ray diffraction, and scanning electron microscopy methods. The tensile strengths of the hydrogels were determined using a standard method (universal testing machine), whereas the electrical conductivities of composite hydrogels of varying compositions were evaluated using a four‐probe method. The bending behavior of the conducting hydrogels was investigated by using the effective bending angle method. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: E520–E530, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21298
Water and Dye Uptake Studies of Acrylamide/4‐Styrenesulfonic Acid Sodium Salt Copolymers and Semi‐Interpenetrating Polymer Networks Composed of Gelatin and/or PVA
Authors: Karadaǧ Erdener , Kundakci Semi̇ha 
Published: August 2012

AbstractGelatin (GEL) and poly(vinyl alcohol) (PVA) based semi‐interpenetrating polymer network (semi‐IPN) hydrogels were prepared as a water adsorbent for cationic dye (methyl violet, MV) sorption. For this case, chemically cross‐linked copolymer of an acrylamide/4‐styrenesulfonic acid sodium salt (AAm/SSS) copolymer with PVA and/or GEL was prepared by polymerization of aqueous solution of acrylamide (AAm) and 4‐styrenesulfonic acid sodium salt (SSS) using ammonium persulfate/N,N,N',N'‐ tetramethylethylenediamine as a redox initiating pair in the presence of poly(ethylene glycol)diacrylate as a cross‐linker. FT‐IR analysis was used to identify the presence of different repeating units in the semi‐IPNs. Surface morphology was characterized by using a scanning electron microscopy technique. Some swelling and diffusion characteristics were calculated for different semi‐IPNs and hydrogels prepared under various formulations. Water uptake and dye sorption properties of the cross‐linked polymeric systems, such as AAm/SSS, AAm/GEL/SSS, AAm/PVA/SSS, and AAm/GEL/PVA/SSS hydrogel systems, were investigated as a function of chemical composition of the hydrogels. MV is used in sorption studies. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E531–E544, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21299
Microphase Separation in Unsaturated Polyester/ PEO‐PPO‐PEO Block Copolymer Mixtures Containing Carbon Nanotubes
Authors: Espósito Leandro H. , Ramos José A. , Builes Daniel H. , Kortaberria Galder , Mondragon Iñaki 
Published: August 2012

AbstractIrregular nanoscale micellar morphology was achieved by mixing an amphiphilic poly(ethylene oxide)‐b‐poly(propylene oxide)‐b‐poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymer with an orthophthalic unsaturated polyester (UP) matrix. These systems were observed fully transparent. Modified matrices were filled with several multiwalled carbon nanotube (MWCNT) contents. Morphological analysis indicated a better dispersion of MWCNT with the use of a block copolymer when compared with a neat UP matrix/MWCNT composite, PEO‐PPO‐PEO acting like a surfactant. Furthermore, MWCNT did not affect the achievement of the irregular nanoscale micellar morphology. A reduction of mechanical properties of the composites with the block copolymer content was observed for UP/PEO‐PPO‐PEO composites without MWCNT. With the addition of MWCNT up to 0.5 wt% content, mechanical properties increased, decreasing again for 1 wt% MWCNT content probably due to the formation of agglomerates despite the use of the block copolymer as a surfactant. Flexural properties of composites decreased due to the incorporation of PEO‐PPO‐PEO copolymer, but significant higher levels of ductility were achieved. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E572–E581, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21302
High Fill Factor Polymer Solar Cells Incorporating a Low Temperature Solution Processed WO3 Hole Extraction Layer
Authors: Stubhan Tobias , Li Ning , Luechinger Norman A. , Halim Samuel C. , Matt Gebhard J. , Brabec Christoph J. 
Published: August 2012

AbstractWe demonstrate solution‐processed tungsten trioxide (WO3) incorporated as hole extraction layer (HEL) in polymer solar cells (PSCs) with active layers comprising either poly(3‐hexylthiophene) (P3HT) or poly[(4,4'‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]silole)‐2,6‐diyl‐alt‐(4,7‐bis(2‐thienyl)‐2,1,3‐benzothiadiazole)‐5,50‐diyl] (Si‐PCPDTBT) mixed with a fullerene derivative. The WO3 layers are deposited from an alcohol‐based, surfactant‐free nanoparticle solution. A short, low‐temperature (80 °C) annealing is sufficient to result in fully functional films without the need for an oxygen‐plasma treatment. This allows the application of the WO3 buffer layer in normal as well as inverted architecture solar cells. Normal architecture devices based on WO3 HELs show comparable performance to the PEDOT:PSS reference devices with slightly better fill factors and open circuit voltages. Very high shunt resistances (over 1 MΩ cm2) and excellent diode rectification underline the charge selectivity of the solution‐processed WO3 layers.
Age‐at‐death estimation in an Italian historical sample: A test of the Suchey‐Brooks and transition analysis methods
Authors: Godde Kanya , Hens Samantha M. 
Published: August 2012

AbstractA growing body of research is demonstrating increased accuracy in aging from a relatively new method, transition analysis. Although transition analysis was developed for paleodemographic research, a majority of subsequent studies have been in the forensic arena, with very little work in bioarchaeological contexts. Using the Suchey‐Brooks pubic symphysis phases, scored on a target sample of historic Italians from the island of Sardinia, we compare accuracy of aging between transition analysis combined with a Bayesian approach and the standard Suchey‐Brooks age ranges. Because of the difficulty in identifying a reasonable informative prior for bioarchaeological samples, we also compared results of both an informative prior and a uniform prior for age estimation.Published ages‐of‐transition for the Terry Collection and Balkan genocide victims were used in conjunction with parameters generated from Gompertz hazard models derived from the priors. The ages‐of‐transition and hazard parameters were utilized to calculate the highest posterior density regions, otherwise known as “coverages” or age ranges, for each Suchey‐Brooks phase. Each prior, along with the parameters, were input into cumulative binomial tests. The results indicate that the Bayesian approach outperformed the Suchey‐Brooks technique alone. The Terry Collection surpassed the Balkans as a reasonable sample from which to derive transition analysis parameters. This discrepancy between populations is due to different within phase age‐at‐death distributions that reflect differences in aging between the populations. These results indicate bioarchaeologists should strive to apply a Bayesian analysis when aging historic and archaeological populations by employing an informative prior. Am J Phys Anthropol 149:259–265, 2012. © 2012 Wiley Periodicals, Inc.
Effects of silica/multiwall carbon nanotube hybrid fillers on the properties of natural rubber nanocomposites
Authors: Ismail H. , Ramly A. F. , Othman N. 
Published: August 2012

AbstractIn this study, multiwalled carbon nanotubes (MWCNTs) and silica were used as hybrid fillers in natural rubber (NR) nanocomposites. The addition of MWCNTs and silica to NR was varied with the total filler loading fixed at 30 phr. The curing characteristics and mechanical, thermal, and morphological properties were investigated in this study. The results show that the scorch and curing time decreased as the MWCNT loading increased in the silica/MWCNT hybrid, but the maximum torque was increased by about 35%. The highest tensile strength was achieved at a loading ratio of 29 phr silica/1 phr MWCNTs. As the MWCNT loading increased in the silica/MWCNT hybrid, the tensile strength, elongation at break, and fatigue life decreased. However, the tensile modulus and rubber filler interaction increased. The scanning electron microscopy results show a good dispersion and better interaction between silica and the MWCNTs with the NR matrix at a 29/1 silica/MWCNT loading ratio. As the MWCNT loading ratio increased, the agglomeration of the MWCNTs became dominant and reduced the reinforcing effect of the MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and properties of 4, 4′‐diphenylmethane diisocyanate blocking modified poly(propylene carbonate)
Authors: Pang Sujuan , Xu Nai , Xu Guang , Pan Lisha , Lin Qiang , Wang Xin 
Published: August 2012

AbstractPoly(propylene carbonate) (PPC) is inferior in thermal stability and liable to incur thermal degradation, especially in the existence of residual bimetal catalyst. In this article, PPC containing residual catalyst was end‐capped with 4, 4′‐diphenylmethane diisocyanate (MDI) through melt compounding. The blends were characterized by infrared spectra, melt flow index (MFI), gel permeation chromatography (GPC), gel content measurement, thermogravimetric analysis, scanning electron microscopy, and tensile test. The effect of MDI on thermal stability, molecular weight, and tensile properties of PPC was studied. Thermal degradation kinetics of neat PPC and PPC+MDI blending samples was discussed with Friedman method. MFI, GPC, and gel content measurements showed that mainly end‐capping reaction was carried out on PPC chains when 0.1% of MDI was added. However, as the amount of MDI exceeded to 0.3%, end‐capping, chain‐extension, and crosslinking reactions were synchronously carried out on PPC. Results showed that the end‐capping, chain‐extension, and crosslinking reaction occurring between PPC and MDI could effectively inhibit the unzipping degradation even when the residual catalyst was not removed thoroughly. When the content of MDI reached 1.0%, the initial degradation temperatures (T‐5%) increased from 176.26°C for neat PPC to 259.56°C. As a result, the processing temperature range and processing time were largely extended, and the heat resistance of PPC was improved remarkably. Meanwhile, the tensile property of the modified PPC was enhanced obviously. It may be due to the fact that the molecular weight and gel content of PPC were increased with the increasing amount of MDI. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Cure kinetics of an acrylated epoxidized hemp oil‐based bioresin system
Authors: Francucci Gaston , Cardona Francisco , Manthey Nathan W. 
Published: August 2012

AbstractIn this work, the cure kinetics of a novel acrylated epoxidized hemp oil (AEHO)‐based bioresin was investigated for the first time by differential scanning calorimetry (DSC) using both isothermal and nonisothermal conditions. This new bioresin was synthesized by the acrylation of a previously epoxidized hemp oil (EHO) bioresin. The curing of the AEHO bioresin showed an autocatalytic behavior with the vitrification phenomenon preventing the conversion reaching unity for all the temperatures studied. It was found that the curing behavior can be modeled with high accuracy using a modified Kamal autocatalytic model that takes into account the vitrification phenomenon. Dynamic activation energies were determined from the Kissinger and Ozawa–Flynn–Wall methods, resulting in 58.87 and 62.02 kJmol−1, respectively. In addition, activation energies associated with the autocatalytic model constants, k1 and k2, were established to be equal to 58.94 and 45.32 kJmol−1, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Influence of temperature on mechanical properties of jute/biopolymer composites
Authors: Løvdal Alexandra , Laursen Louise Løcke , Andersen Tom Løgstrup , Madsen Bo , Mikkelsen Lars Pilgaard 
Published: August 2012

AbstractBiopolymers and natural fibers are receiving wide attention for the potential to have good performance composites with low environmental impact. A current limitation of most biopolymers is however their change in mechanical properties at elevated temperatures. This study investigates the mechanical properties of two biomass‐based polymers, polylactic acid (PLA) and cellulose acetate (CA), as a function of ambient temperature in the range from 5 to 80°C. Tests were done for neat polymers and for jute fiber/biopolymer composites. Micromechanical models were applied to back‐calculate the reinforcement efficiency of the jute fibers. The elastic modulus of neat PLA is constant until a temperature of about 45°C, after which it is decreased rapidly. For neat CA, the elastic modulus is almost constant in the whole temperature range. The maximum stress of the neat biopolymers is consistently reduced. For the jute fiber composites, both the elastic modulus and maximum stress are reduced when the temperature is increased. For the elastic modulus, this is shown to be due to a reduction in the reinforcement efficiency of the jute fibers; i.e., a reduction in the back‐calculated effective elastic modulus of the fibers. Altogether, the results demonstrate that the thermal sensitivity parameters typically provided for polymers, e.g., the glass transition temperature and the heat deflection temperature, cannot be used as sole parameters for determining the gradual change in mechanical properties of polymers and composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Beyond growth rate 0.6: Corynebacterium glutamicum cultivated in highly diluted environments
Authors: Grünberger Alexander , van Ooyen Jan , Paczia Nicole , Rohe Peter , Schiendzielorz Georg , Eggeling Lothar , Wiechert Wolfgang , Kohlheyer Dietrich , Noack Stephan 
Published: August 2012

AbstractFast growth of industrial microorganisms, such as Corynebacterium glutamicum, is a direct amplifier for the productivity of any growth coupled or decoupled production process. Recently, it has been shown that C. glutamicum when grown in a novel picoliter bioreactor (PLBR) exhibits a 50% higher growth rate compared to a 1 L batch cultivation [Grünberger et al. (2012) Lab Chip]. We here compare growth of C. glutamicum with glucose as substrate at different scales covering batch cultivations in the liter range down to single cell cultivations in the picoliter range. The maximum growth rate of standard batch cultures as estimated from different biomass quantification methods is ${\hat {\mu }} = 0.42\pm 0.03\,{\rm h}^{- 1} $ even for microtiter scale cultivations. In contrast, growth in a microfluidic perfusion system enabling analysis of single cells reproducibly reveals a higher growth rate of ${\hat {\mu }} = 0.62\pm 0.02\,{\rm h}^{- 1} $. When in the same perfusion system cell‐free supernatant from exponentially grown shake flask cultures is used the growth rate of single cells is reduced to ${\hat {\mu }} = 0.47\pm 0.02\,{\rm h}^{- 1} $. Likewise, when fresh medium is additionally supplied with 5 mM acetate, a growth rate of ${\hat {\mu }} = 0.51\pm 0.01\,{\rm h}^{- 1} $ is determined. These results prove that higher growth rates of C. glutamicum than known from typical batch cultivations are possible, and that growth is definitely impaired by very low concentrations of byproducts such as acetate. Biotechnol. Bioeng. 2013; 110: 220–228. © 2012 Wiley Periodicals, Inc.
Refolding of detergent‐denatured lysozyme using β‐cyclodextrin‐assisted ion exchange chromatography
Authors: Zhang Li , Zhang Qinming , Wang Chaozhan 
Published: August 2012

ABSTRACTChromatography‐based protein refolding is widely used. Detergent is increasingly used for protein solubilization from inclusion bodies. Therefore, it is necessary to develop a refolding method for detergent‐denatured/solubilized proteins based on liquid chromatography. In the present work, sarkosyl‐denatured/dithiothreitol‐reduced lysozyme was used as a model, and a refolding method based on ion exchange chromatography, assisted by β‐cyclodextrin, was developed for refolding detergent‐denatured proteins. Many factors affecting the refolding, such as concentration of urea, concentration of β‐cyclodextrin, pH and flow rate of mobile phases, were investigated to optimize the refolding conditions for sarkosyl‐denatured lysozymes. The results showed that the sarkosyl‐denatured lysozyme could be successfully refolded using β‐cyclodextrin‐assisted ion exchange chromatography. Copyright © 2012 John Wiley & Sons, Ltd.