bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanocompounds: Better Formulations for Recycled Polyethylene
Authors: de O. Sampaio M. M. B. 
Published: December 2012

AbstractSummary: To improve the properties of recycled PE for pipe applications, additions of nanoclay and adhesion promoter were done. The presence of the nanoclay Cloisite 93A and the polyethylene grafted with maleic anhydride in the compounds have promoted the thermal properties. The possible exfoliation/intercalation of the PE in the nanoclay layers increases the barrier properties and reduced permeation to oxidation agents. The melt flow index, the glass transition temperature and the initial decomposition temperature (TG) have decreased. The XRD analysis has presented increase of interplanar distance in the nanoclay layers. The FTIR analysis has showed a decrease in the oxidation peaks intensity. These results are indicators of nanocomposite/microcomposite formation.
First insights into the syntrophic acetate‐oxidizing bacteria – a genetic study
Authors: Müller Bettina , Sun Li , Schnürer Anna 
Published: December 2012

AbstractSyntrophic acetate‐oxidizing bacteria have been identified as key organisms for efficient biogas production from protein‐rich materials. They normally grow as lithotrophs or heterotrophs, producing acetate through the Wood–Ljungdahl pathway, but when growing in syntrophy with methanogens, they reportedly reverse this pathway and oxidize acetate to hydrogen and carbon dioxide. However, the biochemical and regulatory mechanisms behind the shift and the way in which the bacteria regain energy remain unknown. In a genome‐walking approach, starting with degenerated primers, we identified those gene clusters in Syntrophaceticus schinkii, Clostridium ultunense, and Tepidanaerobacter acetatoxydans that comprise the formyltetrahydrofolate synthetase gene (fhs), encoding a key enzyme of the Wood–Ljungdahl pathway. We also discovered that the latter two harbor two fhs alleles. The fhs genes are phylogenetically separated and in the case of S. schinkii functionally linked to sulfate reducers. The T. acetatoxydans fhs1 cluster combines features of acetogens, sulfate reducers, and carbon monoxide oxidizers and is organized as a putative operon. The T. acetatoxydans fhs2 cluster encodes Wood–Ljungdahl pathway enzymes, which are also known to be involved in C1 carbon metabolism. Isolation of the enzymes illustrated that both formyltetrahydrofolate synthetases of T. acetatoxydans were functionally active. However, only fhs1 was expressed, confirming bidirectional usage of the pathway.
Cell‐free production of integral membrane aspartic acid proteases reveals zinc‐dependent methyltransferase activity of the Pseudomonas aeruginosa prepilin peptidase PilD
Authors: Aly Khaled A. , Beebe Emily T. , Chan Chi H. , Goren Michael A. , Sepúlveda Carolina , Makino Shin‐ichi , Fox Brian G. , Forest Katrina T. 
Published: December 2012

AbstractIntegral membrane aspartic acid proteases are receiving growing recognition for their fundamental roles in cellular physiology of eukaryotes and prokaryotes, and may be medically important pharmaceutical targets. The Gram‐negative Pseudomonas aeruginosa PilD and the archaeal Methanococcus voltae FlaK were synthesized in the presence of unilamellar liposomes in a cell‐free translation system. Cosynthesis of PilD with its full‐length substrate, PilA, or of FlaK with its full‐length substrate, FlaB2, led to complete cleavage of the substrate signal peptides. Scaled‐up synthesis of PilD, followed by solubilization in dodecyl‐β‐d‐maltoside and chromatography, led to a pure enzyme that retained both of its known biochemical activities: cleavage of the PilA signal peptide and S‐adenosyl methionine‐dependent methylation of the mature pilin. X‐ray fluorescence scans show for the first time that PilD is a zinc‐binding protein. Zinc is required for the N‐terminal methylation of the mature pilin, but not for signal peptide cleavage. Taken together, our work identifies the P. aeruginosa prepilin peptidase PilD as a zinc‐dependent N‐methyltransferase and provides a new platform for large‐scale synthesis of PilD and other integral membrane proteases important for basic microbial physiology and virulence.
Synthesis, characterization and properties of biocompatible poly(glycerol sebacate) pre‐polymer and gel
Authors: Li Yuan , Cook Wayne D , Moorhoff Cornelis , Huang Wen‐Chao , Chen Qi‐Zhi 
Published: December 2012

AbstractPoly(glycerol sebacate) (PGS) is an elastomer with potential biomedical applications but it suffers from problems with irreproducible synthesis and the unacceptable toxicity of very soft PGS elastomers. To establish the reason for these problems, PGS was synthesized using different temperatures and reaction times, and the reaction was monitored by titration of the unreacted carboxylic groups and measurement of the mass loss during synthesis. It was found that evaporation of glycerol was a major cause of irreproducibility of the elastomer synthesis and this was more significant at higher reaction temperatures. The polymer microstructure was analysed using NMR spectroscopy and all twelve acylglyceride 13C‐signals as well as two small extra peaks of the residual glycerol were observed for the pre‐polymer. For the PGS gel, the glyceride moieties were characterized using NMR spectroscopy for the first time. The modulus and ultimate tensile strength of the gel increased with longer cure times and at higher cure temperatures while the elongation to break decreased and this was interpreted in terms of network theory. The cell viability of mouse fibroblasts was better for PGS samples with a higher conversion.© 2012 Society of Chemical Industry
Extremely low surface recombination velocities on low‐resistivity n‐type and p‐type crystalline silicon using dynamically deposited remote plasma silicon nitride films
Authors: Duttagupta Shubham , Lin Fen , Wilson Marshall , Boreland Matthew B. , Hoex Bram , Aberle Armin G. 
Published: December 2012

ABSTRACTExtremely low upper‐limit effective surface recombination velocities (Seff.max) of 5.6 and 7.4 cm/s, respectively, are obtained on ~1.5 Ω cm n‐type and p‐type silicon wafers, using silicon nitride (SiNx) films dynamically deposited in an industrial inline plasma‐enhanced chemical vapour deposition (PECVD) reactor. SiNx films with optimised antireflective properties in air provide an excellent Seff.max of 9.5 cm/s after high‐temperature (>800 °C) industrial firing. Such low Seff.max values were previously only attainable for SiNx films deposited statically in laboratory reactors or after optimised annealing; however, in our case, the SiNx films were dynamically deposited onto large‐area c‐Si wafers using a fully industrial reactor and provide excellent surface passivation results both in the as‐deposited condition and after industrial‐firing, which is a widely used process in the photovoltaic industry. Contactless corona‐voltage measurements reveal that these SiNx films contain a relatively high positive charge of (4–8) × 1012 cm−2 combined with a relatively low interface defect density of ~5 × 1011 eV−1 cm−2. Copyright © 2012 John Wiley & Sons, Ltd.
Surface‐relief diffraction gratings' optimization for plasmonic enhancements in thin‐film solar cells
Authors: Jefferies Justin , Sabat Ribal Georges 
Published: December 2012

ABSTRACTMethodical and intensive surface plasmon (SP) excitation trials were carried out on various dielectric‐metal interfaces to optimize plasmonic photocurrent enhancements in organic P3HT‐PCBM photovoltaic thin films. The SPs were optically excited via the diffraction grating method using single, crossed, and parallel grating schemes, with trials yielding optimal grating and film thickness parameters. Photocurrent enhancements up to 355% were demonstrated with TM‐polarized incident light on single and parallel grating structures, while both TM and TE‐polarized incident light enhancements were present on crossed grating structures. When compared with the photocurrent enhancements seen on single gratings, those seen on parallel gratings were comparable in magnitude but were shown over a broader optical band. This broadening of the optical band was due to the simultaneous SP excitations by the two superimposed gratings in the parallel scheme. Copyright © 2012 John Wiley & Sons, Ltd.
Evidences for the unfolding mechanism of three‐dimensional domain swapping
Authors: Liu Zhirong , Huang Yongqi 
Published: December 2012

AbstractThe full or partial unfolding of proteins is widely believed to play an essential role in three‐dimensional domain swapping. However, there is little research that has rigorously evaluated the association between domain swapping and protein folding/unfolding. Here, we examined a kinetic model in which domain swapping occurred via the denatured state produced by the complete unfolding of proteins. The relationships between swapping kinetics and folding/unfolding thermodynamics were established, which were further adopted as criteria to show that the proposed mechanism dominates in three representative proteins: Cyanovirin‐N (CV‐N), the C‐terminal domain of SARS‐CoV main protease (Mpro‐C), and a single mutant of oxidized thioredoxin (Trx_W28Aox).
Structural properties of SnO2 nanowires and the effect of donor like defects on its charge distribution
Authors: Zervos M. , Othonos A. , Tsokkou D. , Kioseoglou J. , Pavlidou E. , Komninou P. 
Published: December 2012

AbstractTin oxide (SnO2) nanowires (NWs) with diameters of 50 nm, lengths up to 100 µm and a tetragonal rutile crystal structure have been grown by low pressure reactive vapour transport on 1 nm Au/Si(001). The free carrier density of the SnO2 NWs measured by THz absorption spectroscopy was found to be n = (3.3 ± 0.4) × 1016 cm−3. Based on this we have determined the one‐dimensional (1D) sub‐band energies, overall charge distribution and band bending via the self‐consistent solution of the Poisson–Schrödinger equations in cylindrical coordinates and in the effective mass approximation. We find that a high density of 1018–1019 cm−3 donor‐like defect related states is required to obtain a line density of 0.7 × 109 close to the measured value by taking the Fermi level to be situated ≈0.7 eV below the conduction band edge at the surface which gives a surface depletion shell thickness of 15 nm. We discuss the origin of the donor‐like states that are energetically located in the upper half of the energy band gap as determined by ultrafast, time‐resolved absorption–transmission spectroscopy.
Synthesis of phase‐controlled iron oxide nanoparticles by pulsed laser ablation in different liquid media
Authors: Maneeratanasarn Prachuporn , Khai Tran Van , Kim So Yeon , Choi Bong Geun , Shim Kwang Bo 
Published: December 2012

AbstractLiquid‐phase pulsed laser ablation (LP‐PLA) is a promising technique for the fabrication of various nanomaterials because this technique is very simple and it is easy to control the experimental parameters. This paper demonstrates the synthesis of phase‐controlled iron oxide magnetic nanoparticles by laser ablation of a bulk α‐Fe2O3 target in the following liquid media: ethanol, D.I. water and acetone. Absorption spectra of the nanocolloidal solutions are measured by UV–Vis spectrophotometer. As‐synthesized nanoparticles, extracted from the colloidal solutions, are characterized by X‐ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM) equipped with X‐ray energy dispersive spectrometry (EDX) and a vibrating sample magnetometer (VSM) to discover crystallinity, phase structure, morphology, elemental compositions and magnetic properties in detail. The experimental results showed that the type of target and the magnitude of laser power play important roles in controlling the uniformity of iron oxide phase in the final product nanoparticles. Laser ablation of the iron oxide target in ethanol and acetone yields crystalline maghemite (γ‐Fe2O3) nanoparticles, while that in D.I. water yields amorphous hematite (α‐Fe2O3). Use of an iron oxide (α‐Fe2O3) target for PLA in all three solvents is able to prevent the formation of metal iron and wustite phases in the final product nanoparticles. Moreover, our nanoparticles obtained in all three solvents possess magnetic behaviour, particularly that obtained in acetone, which has better saturation magnetization than those in ethanol and D.I. water.
From oxides to selenides and sulfides: The richness of the CdI2 type crystallographic structure for thermoelectric properties
Authors: Hébert S. , Kobayashi W. , Muguerra H. , Bréard Y. , Raghavendra N. , Gascoin F. , Guilmeau E. , Maignan A. 
Published: December 2012

AbstractIn this paper, we show how the thermoelectric properties can be modified in crystallographic structures based on the CdI2 type layer, by changing the block layers between these CdI2 type layers or by going from oxides to selenides and sulfides. In the case of oxides, the unique properties generated in these structures will be demonstrated in Bi‐based misfit compounds. By combining Hall effect, resistivity, and Seebeck coefficients in single crystals of this family, the importance of doping and of spin and orbital degeneracy term on the Seebeck coefficient will be shown. From this single crystal investigation, the power factor at 300 K is found to be unexpectedly constant as a function of doping. To further enhance the power factor and thus ZT, it is necessary to modify either the block layer or to perform anionic substitutions. By going from oxides to selenides and sulfides, the decrease of the ionic character can induce a decrease of electrical resistivity. Compared to oxides, the properties can generally be described in a more classical way using Boltzmann transport theory. For these materials, the critical parameter is then thermal conductivity and this quantity can be decreased as shown here by intercalating Cu between the layers (CuxTiS2), or by making solid solution such as TiS2 − xSex. These two approaches will be described here, leading to ZT close to 0.5 and 0.4, at 800 and 700 K, respectively.
Hierarchically porous cobalt oxyhydroxide derived from Morpho‐butterfly wings: Preparation, characterization, and carbon monoxide detection at low temperatures
Authors: Wang Jian‐Wen , Kuo Yi‐Ming 
Published: December 2012

AbstractHierarchical porous cobalt oxyhydroxide (CoOOH) has been successfully synthesized using a Morpho‐butterfly wing as template via a sol–gel dip‐coating process followed by a hydrothermal approach. The precursor concentrations and dip‐coating cycles have a large effect on the morphologies and porous structures of wings‐templated CoOOH according to field emission scanning electron microscopy (FE‐SEM), mercury porosimetry, and Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption investigations. Cross‐sensitivity of the wings‐templated and non‐templated CoOOH sensors to various gases coexisting with the environments was investigated. It is revealed that wings‐templated CoOOH has excellent sensitivity and selectivity to carbon monoxide (CO) due to inheritance of the wing's hierarchical porous structure. The sensing response (S) to CO of wings‐templated CoOOH is about 1.48 times higher than that of non‐templated CoOOH. The optimum working temperature of the wings‐templated CoOOH and wings‐templated Zn‐doped CoOOH for CO detection was roughly 70 °C. The wings‐templated Zn‐doped CoOOH also exhibited high sensitivity (5.68) and selectivity for CO relative to H2 (${{S_{{\rm CO}} } \mathord{\left/ {\vphantom {{S_{{\rm CO}} } {S_{{\rm H}_{{\rm 2}} } }}} \right. \kern-\nulldelimiterspace} {S_{{\rm H}_{{\rm 2}} } }}$ = 4.37). The selective sensing mechanism has been discussed in terms of gas–solid reactions, grain size, and hierarchical porous microstructures.
Influence of substrate planar defects on MOVPE GaN layer growth
Authors: Kamler Grzegorz , Smalc‐Koziorowska Julita , Nowak Grzegorz , Grzegory Izabella , Klepka Marcin T. 
Published: December 2012

AbstractGallium nitride layers were deposited on high‐pressure‐grown GaN substrates containing planar defects. The layer growth above the defects was disturbed and the layer contained terraces. The terraced region was investigated by the molten‐bases defect‐selective etching (DSE), atomic force microscopy (AFM), and transmission electron microscopy (TEM) methods. The AFM measurement showed significant differences in atomic steps densities in different parts of the layer. The TEM investigation revealed the presence of stacking faults and the DSE showed that the substrate planar defect influences the layer growth. The schema of the defect–layer interaction has been proposed.
The defect structure of sapphire produced by implantation of Zr and Zr plus O: threshold fluence for amorphization and optical properties
Authors: Sina Younes , Townsend Peter D. , McHargue Carl J. , da Costa Alves Eduardo Jorge 
Published: December 2012

AbstractZirconium implantation‐induced amorphization has been investigated with Rutherford back scattering spectrometry along a channeling direction (RBS‐C) using 2 MeV He+. Ion implantation was carried out at the energy of 175 keV, with fluences of 2×1015 to 2×1016 Zr+/cm2 at room temperatures. The critical amorphization fluence at room temperature was determined as ∼1.5×1016 Zr+/cm2 corresponding to ∼ 40 dpa; ∼2.7% peak Zr‐concentration) which is a lower damage energy than that reported for implantation with ions of similar mass and energy. The effect of post implantation of oxygen into a pre‐implanted sample (with zirconium) was investigated. The RBS results show that oxygen implantation in a crystalline sample increases the damage only slightly and slightly broadens the Zr profile. For the fluences above thresh‐old for amorphization, post implantation by oxygen has very little effect on the residual damage or on the Zr distribution. The presence of both F and F+ centers were indicated by optical absorption (OA) measurements. The OA spectra show the concentration of F and F+ centers increases with increasing fluence with some changes resulting from oxygen implantation of a pre‐zirconium‐implanted sapphire. This alters the relative concentrations of F and F+ centers. The F‐type center concentrations for the samples were calculated using Smakula's equation. Photoluminescence (PL) at an excitation of 255 nm confirms the presence of both F and F+ centers with emission peaks at about 420 and 325 nm respectively. The PL spectra suggest that oxygen implantation decrease the concentration of the both species, consistent with the OA results (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of jadeite‐like minerals
Authors: Barbosa Renata F. , Reichmann Fernando , Cano Nilo F. , Rocca Rene R. , Watanabe Shigueo 
Published: December 2012

AbstractThree samples of silicate minerals sold to us as being jadeite have been investigated concerning their TL properties and also EPR spectrum of one of them denominated here as JQ1. XRF has shown that one of them is an alkaline feldspar and two other, varieties of quartz; one was called JQ1 and the second one JQ2. JQ1 absorption spectrum is characterized by absorption bands at 410 and 600 nm, responsible for green colour. JQ1's 260 °C and 330 °C TL peaks respond to very high dose, therefore it can be used as high dose dosimeter. The EPR spectrum presented g =4.5 Fe3+ signal and several non‐identified signals in the 3460 to 3500 G interval. The typical E'1centre in quartz was not observed here. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Genome guardian p53 and viral infections
Authors: Sato Yoshitaka , Tsurumi Tatsuya 
Published: December 2012

SUMMARYBecause virus infections elicit various cellular responses that inhibit viral replication and growth, viruses must intervene to attenuate antiviral measures in order to thrive. The genome guardian p53 plays a central part not only in DNA damage responses, inducing cell cycle arrest or apoptosis, but also in the innate host immune control of viral infections by orchestrating diverse signaling pathways originating from many different cellular receptors and sensors. Many viruses have acquired sophisticated mechanisms to regulate p53 functions by deploying subversive proteins and modulating its post‐transcriptional status. In this review, we overview the mechanisms by which DNA and RNA viruses manage p53 signaling in favor of their continued survival. Copyright © 2012 John Wiley & Sons, Ltd.
Fulfilling multiple obligations: Preservice elementary teachers’ use of an instructional model while learning to plan and teach science
Authors: GUNCKEL KRISTIN L. 
Published: December 2012

ABSTRACTRecent efforts to design science methods course frameworks that scaffold preservice teachers in organizing inquiry instructional sequences show promise, yet preservice teachers do not always use these frameworks when they teach in school field placements. This article uses a Discourses lens to explore how two preservice elementary teachers’ sense of obligation shaped their use of an instructional model in their science planning and teaching. The preservice teachers’ course assignments, planned and enacted instructional sequences, and stimulated recall interviews were analyzed to characterize how their sense of obligations as students in a university science methods course and as student teachers in their school field‐placement classrooms enabled and constrained their use of the instructional model. Findings show that the preservice teachers encountered multiple Discourses across communities. These Discourses shaped the obligations that preservice teachers were expected to fulfill. The preservice teachers used the instructional model when it supported them in meeting their obligations to others. These findings have implications for situating teacher orientations in Discourses, understanding the role of mentor teachers in supporting preservice teachers in using instructional models, and framing the function of preservice teachers’ subject‐matter knowledge for using instructional models.
A Springback Compensation Strategy and Applications to Bending Cases
Authors: Liao Juan , Xue Xin , Zhou Chi , Barlat Frederic , Gracio Jose J. 
Published: December 2012

AbstractPart shape error due to springback is a manufacturing defect in the sheet metal forming. This problem can be corrected by adjusting the tool shape to an appropriate shape or process optimization. In this paper, a discrete curvature adjustment (DCA) strategy is developed for tool design of channel bending products. This strategy aims at generating the right tool shape in a short time using the measured data from the trial part. A dynamic compensation factor which varies with part geometry and specific process condition will also be used to adjust the tool curvatures. Applications of this method in the tool design of an asymmetrical U‐shaped part, an industrial blade, and a cylindrical part were presented. The experiment results demonstrated that this strategy was able to reduce the trial times of die modification from five or six to one or two, thus saving time and cost in the industry production. Additionally, the comparison of this method with the existing displacement adjustment (DA) method was also discussed.
JUSTIFICATION AS ‘WOULD-BE’ KNOWLEDGE
Authors: McGlynn Aidan 
Published: December 2012

AbstractIn light of the failure of attempts to analyse knowledge as a species of justified belief, a number of epistemologists have suggested that we should instead understand justification in terms of knowledge. This paper focuses on accounts of justification as a kind of ‘would-be’ knowledge. According to such accounts a belief is justified just in case any failure to know is due to uncooperative external circumstances. I argue against two recent accounts of this sort due to Alexander Bird and Martin Smith. A further aim is to defend a more traditional conception, according to which justification is a matter of sufficiently high evidential likelihood. In particular, I suggest that this conception of justification offers a plausible account of lottery cases: cases in which one believes a true proposition – for example that one's lottery ticket will lose – on the basis of probabilistic evidence.