bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of thiophene units on substituted benzothiadiazole and benzodithiophene copolymers for photovoltaic applications
Authors: Ding Ping , Zou Yingping , Chu Cheng‐Che , Xiao Dequan , Hsu Chain‐Shu 
Published: February 2012

AbstractTwo conjugated copolymers, poly{4,7‐[5,6‐bis(octyloxy)]benzo(c)(1,2,5)thiadiazole‐alt‐4,8‐di(2‐ethylhexyloxyl)benzo[1,2‐b:3,4‐b]dithiophene} (P1) and poly(2‐{5‐[5,6‐bis(octyloxy)‐4‐(thiophen‐2‐yl)benzo(c)(1,2,5)thiadiazol‐7‐yl] thiophen‐2‐yl}‐4,8‐di(2‐ethylhexyloxyl)benzo(1,2‐b:3,4‐b)dithiophene) (P2), composed of benzodithiophene and 5,6‐dioctyloxybenzothiadiazole derivatives with or without thiophene units were synthesized via a Stille cross‐coupling polymerization reaction. These copolymers are promising for applications in bulk heterojunction solar cells because of their good solubility, proper thermal stability, moderate hole mobility, and low band gap. The photovoltaic properties of these copolymers were investigated on the basis of blends of the different polymer/(6,6)‐phenyl‐C71‐butyric acid methyl ester (PC71BM) weight ratios under AM1.5G illumination at 100 mW/cm2. The device with indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/P2:PC71BM (1 : 2 w/w)/Ca/Al gave a relatively better photovoltaic performance with a power conversion efficiency of 1.55%. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Plasticization of polylactide with block copolymers of ethylene glycol and propylene glycol
Authors: Kowalczyk Marcin , Pluta Miroslaw , Piorkowska Ewa , Krasnikova Nelli 
Published: February 2012

AbstractIn this study, plasticization of polylactide (PLA) with PEG–PPG–PEG triblock copolymers was examined. Two different copolymers were utilized, with molecular weight of 1100 and 1900 g mol−1, and with PEG contents of 10 and 50 wt %, respectively. A PPG plasticizer with molecular weight of 1000 g mol−1, close to that of PPG block in the copolymers, was also used for comparison. Melt blends containing 10 and 15 wt % of the plasticizers were prepared. Thermal properties, mechanical properties, and structure of quenched and annealed films of the blends were studied. The crystallization driven phase separation occurred in all the annealed blends but led to different structures depending on the plasticizer used. Distinct inclusions of the plasticizer were visible under the scanning electron microscope only in PLA with PPG but not in the blends of PLA with the copolymers. The drawability of the plasticized systems was improved when compared with neat PLA. In the quenched and annealed blends, elongations at break at the level of 5 and 0.7, respectively, were reached. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of plasticizers suggests role of topology in polymer solidification at high cooling rates
Authors: Piccarolo Stefano , Poulose Anesh Manjaly , Luzio Alessandro 
Published: February 2012

AbstractAlthough solidification in processing determines short‐ and long‐term properties, methods for understanding polymer crystallization mostly rely on real time experiments. Their evidences being drawn on time scales farther apart with respect to those experienced in processing. Nor significant outcomes have been so far drawn with approaches mimicking the typical processing times, the Continuous Cooling Transformation methods. Use of these techniques has indeed been limited to a heuristic interpretation of the structure developed under extreme solidification conditions without suggesting alternative routes to the understanding or even clues to the many open questions on polymer crystallization under realistic solidification conditions. If the mechanisms inferred from realtime methods cannot in principle be translated to processing conditions the oxymoron is not overcome. In this work, we compare the influence of a plasticizer on the density drop with cooling rate, and therefore on the disappearance of any long range order crystalline phases, observed after fast controlled quenching of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). The plasticizer enhances significantly the maximum cooling rate at which PET still shows long range order crystalline phases, whereas barely modifies the situation for PBT. On the basis of a series of concurrent clues, we suggest that the complex inherent topology of macromolecular melts introduces a timescale on polymer crystallization lying in the range of the solidification conditions experienced in processing. Although melt topology is known to determine in many instances polymer solidification, all approaches so far proposed to describe the development of polymer crystallization overlook or even neglect any explicit dependence of such mechanisms on parameters like the molecular weight between entanglements. Albeit the arguments are feeble they all concur to raise several questions even on the contradictory role of nucleating agents under the extreme conditions experienced in processing. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The role of dislocations for the plastic deformation of semicrystalline polymers as investigated by multireflection X‐ray line profile analysis
Authors: Spieckermann Florian , Polt Gerald , Wilhelm Harald , Kerber Michael , Schafler Erhard , Zehetbauer Michael J. 
Published: February 2012

AbstractWide angle X‐ray experiments evaluated by recent developments of X‐ray line profile analysis allow for the detection of the presence of dislocations as well as to determine their density in crystalline materials. The application to semicrystalline polymers not only provides information on the crystal size and the dislocations but—in combination with in situ deformation—also information on the evolution of these microstructural parameters. Investigations on cold rolled and on uniaxially compressed samples of α‐phase isotactic polypropylene (α‐iPP) as well as poly(3‐hydroxybutyrate) (P3HB) are presented. The synchrotron experiments reveal a dislocation governed deformation process in α‐iPP. P3HB, however, deforms by a process not including dislocation generation. Here, microcracking and strain localization in the amorphous phase seem to be the predominant deformation mechanisms. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Properties of ultra‐high‐molecular‐weight polyethylene with a structure modified by plastic deformation and electron‐beam irradiation
Authors: Cybo Jerzy , Maszybrocka Joanna , Duda Piotr , Bartczak Zbigniew , Barylski Adrian , Kaptacz Sławomir 
Published: February 2012

AbstractTo improve the functional properties of polyethylene in a polymer–metal kinematic system, ultra‐high‐molecular‐weight polyethylene (UHMWPE) was subjected to light deformation by uniaxial compression [permanent true strain (ef) = 0.14–0.32] and postdeformation electron‐beam irradiation (with a dose of 26–52 kGy). X‐ray examinations demonstrated that no significant reorientation of the lamellar structure occurred upon compression. The textures of all of the samples, except for the sample deformed at ef = 0.32, were nearly random. In the exception, a very weak axial texture developed. However, the treatment applied (deformation and electron‐beam irradiation) significantly changed the structure of the material. A considerable increase in the crosslinked fraction and the crystalline band absorption in the Fourier transform infrared spectra were observed in the modified samples. This indicated a noticeable increase in the degree of spatial ordering within a structure, although the overall crystallinity increased only slightly. The effect of such restructuring was evidenced by microscopic observations of the near‐surface layer of the UHMWPE samples subjected to unidirectional sliding interaction with a CoCr alloy for 100 h (in a block‐ring tribological system). It was found that for the predeformed (ef = 0.14–0.21) and electron‐irradiated (dose of 52 kGy) samples, the operational load imposed on the system resulted in a considerable reduction in the thickness of the plastically deformed near‐surface layer and in a decreasing amount of lamellae oriented flat‐on compared to the neat unmodified UHMWPE subjected to the same test. The recorded tribological wear (mass decrement) decreased up to fivefold in comparison to that of the initial material. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Resistance of UHMWPE to plastic deformation and wear and the possibility of its enhancement through modification by radiation
Authors: Cybo Jerzy , Maszybrocka Joanna , Barylski Adrian , Kansy Jerzy 
Published: February 2012

AbstractThe operational durability of a kinematical polymer–metal system, required in many applications, including endoprostheses used for the total knee or hip joint arthoplasty, depends largely on high resistance to wear and permanent deformation of the polymer cup, especially in its near‐surface layer, contacting with the metal part. In this study, the wear and deformation resistance of two ultra high molecular weight polyethylene (UHMWPE) grades used in arthoplasty, GUR1020 and GUR1050, as well as the possibilities of its enhancement by radiation treatment were studied in detail. An influence of the molecular characteristic of these grades on functional properties, including permanent plastic deformation, microhardness, elastic modulus, coefficient of the micromechanical wear were studied. The properties of GUR 1050 of higher molecular weight were found advantageous over GUR 1020 grade. It was also confirmed that irradiation with electron beam is an effective method of modification, resulting in an improvement of both resistance to permanent deformation and wear of UHMWPE. It was demonstrated that microhardness, Young's modulus, and wear resistance coefficient increase proportionally to the irradiation dose applied. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Transcriptional profile of native CD271+ multipotential stromal cells: Evidence for multiple fates, with prominent osteogenic and Wnt pathway signaling activity
Authors: Churchman Sarah M. , Ponchel Frederique , Boxall Sally A. , Cuthbert Richard , Kouroupis Dimitrios , Roshdy Tarek , Giannoudis Peter V. , Emery Paul , McGonagle Dennis , Jones Elena A. 
Published: February 2012

AbstractObjectiveControversy surrounds the identity and functionality of rare bone marrow–derived multipotential stromal cells (BM‐MSCs), including their differentiation capabilities, their relationship to pericytes and hematopoiesis‐supporting stromal cells, and the relevance of their culture‐expanded progeny in studies of skeletal biology and development of cell‐based therapies. The aim of this study was to clarify the nature of candidate BM‐MSCs by profiling transcripts that reflect different aspects of their putative functions in vivo.MethodsRare, sorted BM‐derived CD45−/low CD271bright (CD271) cells were analyzed using 96‐gene expression arrays focused on transcripts relevant to mesenchymal‐lineage differentiation (toward bone, cartilage, fat, or muscle), hematopoietic and stromal support, and molecules critical to skeletal homeostasis. These cells were compared to matched CD45+ CD271− hematopoietic‐lineage cells, culture‐expanded MSCs, and skin fibroblasts. When feasible, transcription was validated using flow cytometry.ResultsCD271 cells had a transcriptional profile consistent with the multiple fates of in vivo MSCs, evident from the observed simultaneous expression of osteogenic, adipogenic, pericytic, and hematopoiesis‐supporting genes (e.g., SP7 [osterix], FABP4 [fatty acid binding protein 4], ANGPT1 [angiopoietin 1], and CXCL12 [stromal cell–derived factor 1], respectively). Compared to culture‐expanded MSCs and fibroblasts, CD271 cells exhibited greater transcriptional activity, particularly with respect to Wnt‐related genes (>1,000‐fold increased expression of FRZB [secreted frizzled‐related protein 3] and WIF1 [Wnt inhibitory factor 1]). A number of transcripts were identified as novel markers of MSCs.ConclusionThe native, BM‐derived in vivo MSC population is endowed with a gene signature that is compatible with multiple functions, reflecting the topographic bone niche of these cells, and their signature is significantly different from that of culture‐expanded MSCs. This indicates that studies of the biologic functions of MSCs in musculoskeletal diseases, including osteoporosis and osteoarthritis, should focus on in vivo MSCs, rather than their culture‐adapted progeny.
Abnormal bone quality in cartilage oligomeric matrix protein and matrilin 3 double‐deficient mice caused by increased tissue inhibitor of metalloproteinases 3 deposition and delayed aggrecan degradation
Authors: Groma Gergely , Xin Wei , Grskovic Ivan , Niehoff Anja , Brachvogel Bent , Paulsson Mats , Zaucke Frank 
Published: February 2012

AbstractObjectiveCartilage oligomeric matrix protein (COMP) and matrilin 3 are extracellular matrix proteins that are abundant in cartilage. As adaptor molecules, both proteins bridge and stabilize macromolecular networks consisting of fibrillar collagens and proteoglycans. Mutations in the genes coding for COMP and matrilin 3 have been linked to human chondrodysplasias, while in mice, deficiency in COMP or matrilin 3 does not cause any pronounced skeletal abnormalities. Given the similar functions of COMP and matrilin 3 in the assembly and stabilization of the extracellular matrix, our aim was to determine whether these proteins could functionally compensate for each other.MethodsTo assess this putative redundancy of COMP and matrilin 3, we generated COMP/matrilin 3 double‐deficient mice and performed an in‐depth analysis of their skeletal development.ResultsAt the newborn stage, the overall skeletal morphology of the double mutants was normal, but at 1 month of age, the long bones were shortened and the total body length reduced. Peripheral quantitative computed tomography revealed increased metaphyseal trabecular bone mineral density in the femora. Moreover, the degradation of aggrecan in the cartilage remnants in the metaphyseal trabecular bone was delayed, paralleled by increased deposition of tissue inhibitor of metalloproteinases 3 (TIMP‐3). The structure and morphology of the growth plate were grossly normal, but in the center, focal closures were observed, a phenotype very similar to that described in matrix metalloproteinase 13 (MMP‐13)–deficient mice.ConclusionWe propose that a lack of COMP and matrilin 3 leads to increased deposition of TIMP‐3, which causes partial inactivation of MMPs, including MMP‐13, a mechanism that would explain the similarities in phenotype between COMP/matrilin 3 double‐deficient and MMP‐13–deficient mice.
Benchmarking of next‐generation biofuels from a process perspective
Authors: Voll Anna , Marquardt Wolfgang 
Published: February 2012

AbstractRecently, novel biofuel candidates have been proposed by catalysis research. To guide follow‐up research activities efficiently, it must be assessed whether large‐scale production of such next‐generation biofuels is competitive in comparison with established biofuels like ethanol. However, it is very time‐consuming to provide complete process designs for all alternatives, especially as important data are missing in the early development phase. Instead, reaction network flux analysis (RNFA) has been introduced recently for rapid screening of production routes to bridge the gap between catalysis research and process design. Using this approach, mass balances are formulated for a network of possible reactions such that multi‐objective optimization techniques can be applied to identify the attractive pathways with high performance. Typical performance indicators like total annualized cost or environmental impact are adapted to the requirements of the early design phase and integrated in the flux analysis. In this paper, production performance indicators of ten novel biofuel candidates are compared to those of methanol, ethanol, butanol, and methane as reference fuels using RNFA. While some pathways already show an encouraging performance, the reaction yield of others must be increased significantly, if the target product should qualify as promising fuel candidates. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd
Reaction kinetics in the plasma membrane
Authors: Kalay Ziya 
Published: February 2012

AbstractA great puzzle in science is establishing a bottom up understanding of life by revealing how a collection of molecules gives rise to a living cell that can survive, communicate, and reproduce. In the confines of physics, chemistry, or material science laboratories where it possible to study complex interactions between molecules in a well‐defined environment, our understanding of collective behavior is substantially developed. However, the environment in which molecules of a biological cell perform their functions is far from ideal or controllable. The environment inside cellular regions such as the plasma membrane is heterogeneous and dynamic, and functional molecules such as proteins are both dynamic and promiscuous, as they interact with countless other molecules. This makes it extremely challenging to grasp the inner mechanism of the cells, both experimentally and theoretically. On the bright side, this presents scientists with a colorful playground that waits to be explored: the mesoscopic world inside the cell. This review covers some of the recent experimental and theoretical developments in the study of molecular interactions in the plasma membrane, viewed as a heterogeneous medium where the number of reactants can be small, sometimes countable, and its implications for biological function.
Functional classification of membrane transporters and channels based on filtered TM/non‐TM amino acid composition
Authors: Schaadt N. S. , Helms V. 
Published: February 2012

AbstractMembrane transporters catalyze the transport of small solute molecules across biological barriers such as lipid bilayer membranes. As the experimental annotation of which proteins transport which substrates is incomplete it is highly desirable to develop computational methods that can assist in the classification and substrate annotation of putative membrane transport proteins. Here, we determined the similarity of membrane transporter sequences annotated in the Transport Classification Database (Saier et al., Nucleic Acids Res 2006, 34, D181‐D186) and Arabidopsis thaliana membrane transporters annotated in the database Aramemnon (Schwacke et al., Plant Physiol 2003, 131, 16‐26). The similarity measure was based on the amino acid composition either considering the full sequences or separately in the transmembrane (TM) and external parts of the sequences. We considered four different substrate sets and three different subfamilies and tried to classify the given proteins into these classes. Family or substrate prediction based on the simple amino acid frequency had an average accuracy of 76%. The differentiation between TM and non‐TM regions led to an improved accuracy of 80% on average. © 2012 Wiley Periodicals, Inc. Biopolymers 97:558–567, 2012.
Extraction and characterization of a natural rubber from Euphorbia characias latex
Authors: Spanò Delia , Pintus Francesca , Mascia Claudia , Scorciapino Mariano Andrea , Casu Mariano , Floris Giovanni , Medda Rosaria 
Published: February 2012

AbstractA natural rubber was identified and characterized for the first time in the latex of the perennial Mediterranean shrub Euphorbia characias. Four different methods, i.e., acetone, acetic acid, trichloroacetic acid, and Triton® X‐100, followed by successive treatments with cyclohexane/ethanol, were employed to extract the natural rubber. The rubber content was shown to be 14% (w/v) of the E. characias latex, a low content compared with that of Hevea brasiliensis (30–35%) but a similar content to other rubber producing plants. E. characias rubber showed a molecular weight of 93,000 with a Mw/Mn of 2.9. 1H NMR, 13C NMR, and FTIR analysis revealed the characteristic of the cis‐1,4‐polyisoprene typical of natural rubber. These results provided novel insight into latex components and will ultimately benefit the broader understanding of E. characias latex composition. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 589–594, 2012.
Age‐Related Differences in Ethnic Prejudice: Evidence of the Mediating Effect of Right‐Wing Attitudes
Authors: Franssen Vicky , Dhont Kristof , Hiel Alain Van 
Published: February 2012

ABSTRACTThe present study revealed age‐related differences in ethnic prejudice in a heterogeneous (total N = 1,308) and a representative (N = 800) sample, using measures of blatant and subtle prejudice. The relationship between age and blatant and subtle prejudice was found to be fully mediated by right‐wing social‐cultural attitudes (i.e. authoritarianism and cultural conservatism). Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis of C8‐Arylamine‐Modified 2′‐Deoxyadenosine Phosphoramidites and their Site‐Specific Incorporation into Oligonucleotides
Authors: Szombati Zita , Baerns Sabrina , Marx Andreas , Meier Chris 
Published: February 2012

AbstractAdducts of C8‐(N‐acetyl)‐arylamines and 2′‐deoxyadenosine were synthesised by palladium‐catalysed CN cross‐coupling chemistry. These 2′‐dA adducts were converted into the corresponding 3′‐phosphoramidites and site‐specifically incorporated into DNA oligonucleotides, which were characterised by mass spectrometry, UV thermal‐stability assays and circular dichroism. These modified oligonucleotides were also used in EcoRI restriction assays and in primer‐extension studies with three different DNA polymerases. The incorporation of the 2′‐dA lesion close to the EcoRI restriction site dramatically reduced the susceptibility of the DNA strand to cleavage; this indicates a significant local distortion of the DNA double helix. The incorporation of the acetylated C8‐2′‐dA‐phosphoramidites into 20‐mer oligonucleotides failed, however, because the N‐acetyl group was lost during the deprotection process. Instead the corresponding C8‐NH‐2′‐dA‐modified oligonucleotides were obtained. The effect of the C8‐NH‐arylamine‐dA lesion on the replication by DNA polymerases was clearly dependent both on the polymerase used and on the arylamine‐dA damage.
Tailoring a Stabilized Variant of Hydroxynitrile Lyase from Arabidopsis thaliana
Authors: Okrob Daniel , Metzner Julia , Wiechert Wolfgang , Gruber Karl , Pohl Martina 
Published: February 2012

AbstractThe R‐selective hydroxynitrile lyase from Arabidopsis thaliana (AtHNL) cannot be applied for stereoselective cyanohydrin syntheses in aqueous media because of its limited stability at pH<5, which is required in order to suppress the uncatalyzed racemic cyanohydrin formation. To stabilize AtHNL we designed a surface‐modified variant incorporating 11 changes in the amino acids on the protein surface. Comparative characterization of the variant and the wild‐type enzyme showed a broadened pH optimum towards the acidic range, along with enhancement of activity by up to twofold and significantly increased pH‐ and thermostabilities. The effect can most probably be explained by a shift of the isoelectic point from pH 5.1 to 4.8. Application of the variant for the synthesis of (R)‐cyanohydrins in an aqueous/organic two‐phase system at pH 4.5 demonstrated the high stereoselectivity and robustness of the variant relative to the wild‐type enzyme, which is immediately inactivated under these conditions.