bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of linseed oil‐based nanocomposites
Authors: Sharma Vinay , Banait J.S. , Larock R.C. , Kundu P.P. 
Published: March 2009

AbstractThe nanocomposites from conjugated linseed oil, acrylic acid, and divinylbenzene are synthesized using modified montmorillonite clay and characterized for thermal properties. The wide angle X‐ray diffraction results clearly show the distortion of the platy nanolayers of the nanofiller in the polymer matrix as the peak due to the clay disappears in the nanocomposite samples. The dynamic mechanical analysis results show the enhanced storage modulus and transition temperature compared with the pristine polymer. At the glass transition temperature, the storage modulus of nanocomposites is in the range of 17–79 MPa, whereas the pristine polymer shows a storage modulus of 2.1 MPa. The melting peak temperature ranges from 230 to 260°C, which is further confirmed by thermogravimetric analysis (TGA) results. The samples are stable up to 200°C and show a two‐stage degradation. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Selective laser sintering of clay‐reinforced polyamide
Authors: Jain Prashant K. , Pandey Pulak M. , Rao P.V.M. 
Published: March 2009

AbstractAn experimental investigation has been carried out to study the feasibility of processing blended powder of polyamide (PA) and organically modified nanoclay using selective laser sintering. The effect of nanoclay on the sintering parameters and mechanical properties of the sintered specimen have been studied. This article presents the details of preprocessing studies required and conducted to find suitability of the blended powder material to be processed on SLS machine. A suitable part bed temperature has also been found to avoid curling as well as to ensure the powder reusability. In this work, laser power, beam speed, scan spacing have been considered as influential operating process parameters and are explored using Taguchi's L9 orthogonal array. Tensile specimens of PA and PA/clay composite have been fabricated as per ASTM D638 standard and tested for ultimate tensile strength, elongation at break, and Young's modulus using universal testing machine. Ultimate tensile strength and elongation at break are found to be decreased in case of PA/clay composite when compared with virgin polyamide. To understand the sintering insight and to explain the behavior of obtained mechanical properties, further investigations have been carried out using material characterization techniques like X‐ray diffraction and scanning electron microscopy. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Synthesis and characterization of fluorinated poly(etherimide)s toughening for carbon fiber‐reinforced epoxy composites
Authors: Chen Weiming , Tao Zhiqiang , Fan Lin , Yang Shiyong , Jiang Wenge , Wang Junfeng , Xiong Yanli 
Published: March 2009

AbstractNovel‐fluorinated poly(etherimide)s (FPEIs) with controlled molecular weights were synthesized and characterized, which were used to toughen epoxy resins (EP/FPEI) and carbon fiber‐reinforced epoxy composites (CF/EP/FPEI). Experimental results indicated that the FPEIs possessed outstanding solubility, thermal, and mechanical properties. The thermally cured EP/FPEI resin showed obviously improved toughness with impact strength of 21.1 kJ/m2 and elongation at break of 4.6%, respectively. The EP/FPEI resin also showed outstanding mechanical strength with tensile strength of 91.5 MPa and flexural strength of 141.5 MPa, respectively. The mechanical moduli and thermal property of epoxy resins were not affected by blending with FPEIs. Furthermore, CF/EP/FPEI composite exhibited significantly improved toughness with Mode I interlaminar fracture toughness (GIC) of 899.4 J/m2 and Mode II interlaminar fracture toughness (GIIC) of 1017.8 J/m2, respectively. Flexural properties and interlaminar shear strength of the composite were slightly increased after toughening. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Stationary cuvette: a new approach to obtaining analytical curves by UV–VIS spectrophotometry
Authors: Silva K. G. H. , Júnior F. H. Xavier , Farias I. E. G. , Silva A. K. A. , Neto J. A. Caldas , Souza L. C. A. , Santiago R. R. , Júnior F. Alexandrino , Júnior T. Nagashima , Soares L. A. L. , Santos‐Magalhães N. S. , Egito E. S. T. 
Published: March 2009

AbstractBackgroundInvestigations in the field of pharmaceutical analysis and quality control of medicines require analytical procedures that achieve suitable performance. An analytical curve is one of the most important steps in the chemical analysis presenting a direct relationship to features such as linearity.ObjectiveThis study has the aim of developing a new methodology, the stationary cuvette, to derive analytical curves by spectroscopy for drug analysis.MethodologyThe method consists basically of the use of a cuvette with a path length of 10 cm, containing a constant volume of solvent in which increasing amounts of a stock solution of the sample are added, droplet by droplet. After each addition, the cuvette is stirred and the absorbance is measured. This procedure was compared with the currently used methodology, which requires a labour‐intensive dilution process, and possible sources of variation between them were evaluated.ResultsThe results demonstrated that the proposed technique presented high sensitivity and similar reproducibility compared with the conventional methodology. In addition, a number of advantages were observed, such as user‐friendliness, cost‐effectiveness, accuracy, precision and robustness.ConclusionThe stationary cuvette approach may be considered to be an appropriate alternative to derive analytical curves for analysing drug content in raw materials and medicines through UV–VIS spectrophotometry. Copyright © 2009 John Wiley & Sons, Ltd.
Isothermal crystallization kinetics of silk fibroin fiber‐reinforced poly(ε‐caprolactone) biocomposites
Authors: Qiao Xiuying , Li Wei , Sun Kang , Xu Shi , Chen Xiaodong 
Published: March 2009

AbstractBACKGROUND: Poly(ε‐caprolactone) (PCL) has attracted great attention due to its wide applications for pharmaceutical controlled released systems and implanted polymer devices. In this study, silk fibroin fiber (SF) obtained from degumming treatment of silk was used to prepare novel reinforced PCL biocomposites. The isothermal crystallization behavior of these composites was investigated using differential scanning calorimetry measurements.RESULTS: With a decrease of isothermal crystallization temperature (Tc) and an increase of fiber filler, the crystallization time of the SF/PCL composites becomes shorter, the crystallization rate constant (K) increases and the Avrami exponent (n) gradually decreases (being between 1 and 2). The crystallization of PCL and SF/PCL composites occurs in the same regime. With the gradual addition of fiber, lateral surface free energy (σ) is nearly unchanged, but fold surface free energy (σe) decreases.CONCLUSION: Heterogeneous nucleation is dominant and different growth morphologies coexist during the isothermal crystallization process of the SF/PCL hybrid systems. Although the introduction of SF obviously increases the overall crystallization rate of PCL, the growth rate constant and nucleation constant of PCL are reduced because of the confinement effect of fiber network structures on the molecular mobility of polymer molecular chains. Copyright © 2009 Society of Chemical Industry
A survey of once‐daily dosage tobramycin therapy in patients with cystic fibrosis
Authors: Van Meter Daniel J. , Corriveau Michele , Ahern John W. , Lahiri Thomas 
Published: March 2009

AbstractThe purpose of this study was to quantify the prevalence of once‐daily dosage of tobramycin (ODDT) among Cystic Fibrosis Foundation‐accredited care centers and affiliated programs (CFFACCs) and characterize the ODDT approaches used by these institutions. An anonymous cross‐sectional survey of CFFACCs was performed using an electronic survey tool. This tool was electronically mailed to the program directors. Eighty‐four out of 195 institutions completed the survey (response rate = 43%). Fifty‐one (61%) of 84 centers reported using ODDT. Of those 51 institutions, 34 (67%) use a dosage of 10 mg/kg/dose. Serum creatinine was measured routinely in 51 centers (100%) with weekly monitoring being used in 40 centers (78%). Audiometric evaluation was performed routinely in 22 (43%) centers with annual assessment performed in 14 (64%) of these 22 centers. In conclusion, a majority of responding institutions use ODDT. The most common reported dosage is 10 mg/kg. Serum creatinine was routinely measured in all institutions with weekly assessment being the most common frequency. Audiometic assessment is routinely performed in <50% of centers. Of the institutions performing audiograms routinely, annual assessment is the most common frequency. Pediatr Pulmonol. 2009; 44:325–329. © 2009 Wiley‐Liss, Inc.
The thermo‐ and acido‐stable ORF‐99 from the archaeal virus AFV1
Authors: Goulet Adeline , Spinelli Silvia , Blangy Stéphanie , van Tilbeurgh Herman , Leulliot Nicolas , Basta Tamara , Prangishvili David , Cambillau Christian , Campanacci Valérie 
Published: March 2009

AbstractAcidianus Filamentous Virus 1 (AFV1), isolated from acidic hot springs, is an enveloped lipid‐containing archaeal filamentous virus with a linear double‐stranded DNA genome. It infects Acidianus, which is a hyperthermostable archaea growing at 85°C and acidic pHs, below pH 3. AFV1‐99, a protein of 99 amino acids of unknown function, has homologues in the archaeal virus families Lipothrixviridae and Rudiviridae. We determined the crystal structure of AFV1‐99 at 2.05 Å resolution. AFV1‐99 has a new fold, is hyperthermostable (up to 95°C) and resists to extreme pH (between pH 0 and 11) and to the combination of high temperature (95°C) and low pH (pH 0). It possesses characteristics of hyperthermostable proteins, such as a high content of charged residues.
Manifestation of ripples in free‐standing graphene in lattice images obtained in an aberration‐corrected scanning transmission electron microscope
Authors: Bangert U. , Gass M. H. , Bleloch A. L. , Nair R. R. , Geim A. K. 
Published: March 2009

AbstractThe shape of ripples in free‐standing graphene is derived from bond length distributions in high‐angle annular‐dark‐field (Z‐contrast) images, obtained in an aberration‐corrected scanning transmission electron microscope (superSTEM). Local undulation patterns can readily be visualized by applying fast Fourier transform procedures to the lattice images, using a spatial frequency filter which passes the precise graphitic a ‐plane spacing. Using aberration‐corrected STEM presents the unique opportunity to correlate atomic resolution imaging with the undulations. Values for projected bond lengths, and hence bond inclinations, can be obtained by adjusting the filter to the appropriate band pass. Ripples with amplitude ∼0.5 nm and width ∼5 nm were observed. Their patterns modify in repeated image scans, with prolonged scanning introducing vacancies. These, in conjunction with adatoms which are also revealed in Z‐contrast, induce highly localized changes in the mechanical properties of graphene. Ripples in defected graphene remain dynamic, with changes occurring together with redistribution of defects. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, mechanical and I –V characteristics of Ag–PVA nanocomposite films
Authors: Gautam A. , Ram S. 
Published: March 2009

AbstractHybrid polymer–inorganic nanocomposites have been prepared from an aqueous solution of polyvinyl alcohol (PVA) and silver nitrate (AgNO3). The silver nanoparticles have been generated in PVA matrix by reduction of silver ion with PVA molecules at 60–70 °C over a magnetic stirrer. X‐ray diffraction studies, UV–visible analysis, transmission electron microscopy, scanning electron microscopy and current–voltage analysis were used to characterize the nanocomposite films prepared. The X‐ray diffraction studies showed that silver metal is present in a face‐centered cubic (fcc) crystal structure with average crystallite size 19 nm, which grows to 22 nm on annealing the film at 150 °C in air. This is in good agreement with the result obtained from TEM. The UV–visible spectrum shows a single peak at 433 nm, arising from the surface plasmon absorption of silver colloids. This result clearly indicates that silver nanoparticles are embedded in PVA. An improvement of mechanical properties (storage modulus) was also noticed due to a modification of PVA up to 0.5 wt% of silver content. The current–voltage (I–V) characteristics nanocomposite films obey Ohm's law and the current drawn increases with increasing Ag content in the films. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficiency and non‐thermal roll‐over of violet emitting GaInN light‐emitting diodes grown on substrates with different dislocation densities
Authors: Maier Markus , Passow Thorsten , Kunzer Michael , Pletschen Wilfried , Liu Shangjing , Wiegert Joachim , Schmidt Ralf , Köhler Klaus , Wagner Joachim 
Published: March 2009

AbstractThree series of 400 nm light‐emitting diodes (LED) with GaInN well widths ranging from 3 nm to 18 nm were grown on freestanding GaN‐substrates, on ultra low dislocation GaN templates on sapphire, and directly on sapphire substrates using conventional low temperature nucleation. The resulting defect densities in the active layers range from 4 × 107 to 1 × 109 cm‐2. Employing pulsed electroluminescence (EL) measurements to assess the EL efficiency over a wide range of current densities up to 650 A/cm2, the LEDs grown on defect reduced substrates showed the highest EL efficiency among all devices, which was achieved for GaInN well widths >10 nm and at comparatively high current densities (>100 A/cm2). In contrast, conventional 3 nm wide quantum well LEDs showed the peak EL efficiency at low current densities (<100 A/cm2), irrespective of the type of substrate used. While LEDs grown directly on sapphire showed a pronounced short‐wavelength shift of the EL spectrum by as much as 35 nm upon increasing current densities for intermediate GaInN well widths around 10 nm, the EL spectra of LEDs grown on low defect density templates or substrates occur at an almost constant wavelength which shifts by less than 5 nm upon variation of the current density from 0.5 A/cm2 to 300 A/cm2. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A study of the grain size and electric properties of Mn‐doped ZnO thin films grown by plasma‐assisted molecular beam epitaxy
Authors: Lin Hung‐Ji , Lin Der‐Yuh , Hong Jia‐Zheng , Yang Chu‐Shou , Lin Chih‐Ming , Lin Chia‐Feng 
Published: March 2009

AbstractIn this study, we investigated the effect of manganese (Mn) doping on the grain size and electrical properties of Zn1‐xMnxO films grown on c ‐sapphire substrates by plasma‐assisted molecular beam epitaxy (PAMBE). Compared with the Raman spectra of reference ZnO films grown at the same conditions without Mn‐doping, the Mn related mode is observed and studied. The surface morphology and grain size were investigated by atomic force microscopy (AFM). The results show that the grains become smaller with increasing the Mn doping content. The electric properties including carrier concentration and mobility have been studied by Hall measurements. The decrease in mobility and the increase in resistivity of the samples with higher Mn doping content might be related to an increase of impurity scattering centers. The electric properties of the grain interior and grain boundary have been studied by using impedance spectroscopy (IS). Based on the IS data, we found that the relaxation time increases gradually with increasing Mn doping content. Besides, the activation energy for grain and grain boundary conduction are studied. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Catalyst free MBE‐VLS growth of GaAs nanowires on (111)Si substrate
Authors: Paek J. H. , Nishiwaki T. , Yamaguchi M. , Sawaki N. 
Published: March 2009

AbstractThe behaviour of catalyst free GaAs nanowire growth is investigated on (111)Si substrate by molecular beam epitaxy under different Ga and As fluxes. It is found that the diameter of nanowire is increased by increasing the Ga flux, while it is decreased by increasing the As flux. The growth rate along the wire axis is enhanced by increasing the As flux under a constant Ga flux. Moreover, the Ga droplet at the top disappears by the growth interruption and the growth along the wire axis is strictly prohibited. By adopting the last result, the growth of GaAs/AlGaAs core‐shell structure is attempted. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress‐induced Curie temperature increase in the Fe64Ni36 invar alloy
Authors: Gorria Pedro , Boada Roberto , Fernández‐Martínez Alejandro , Garbarino Gastón , Smith Ronald I. , Chaboy Jesús , Alonso J. I. García , Martínez‐Blanco David , Castro German R. , Mezouar Mohamed , Hernando Antonio , Blanco Jesús A. 
Published: March 2009

AbstractStructural and magnetic changes on invar Fe64Ni36 alloy (TC = 500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X‐ray diffraction under high pressures and X‐ray absorption at both Fe and Ni K‐edges. We argue that the strain induced in the Fe64Ni36 material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature (ΔTC = 70 K). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical insights into the thiol reductase activity of ebtellur
Authors: Sakimoto Yukiko , Hirao Kimihiko , Musaev Djamaladdin G. 
Published: March 2009

AbstractReductase activity of ebtellur was studied at the density functional level. For this purpose, the mechanism and controlling factors of the reactions EbTeO + 2GSH → EbTe + GS‐SG + H2O (2) and EbTeO + H2O + 2GSH → EbTe(OH)2 + 2GSH → EbTe + GS‐SG + 2H2O (3) were analyzed. It was shown that the addition of the first thiol molecule to 2_TeO (model of EbTeO), which occurs with a few kcal/mol activation barrier and exothermic by 20–25 (9–13) kcal/mol, leads to 2_TeO, 2_Te(OH)(SMe), II, intermediate. Addition of the next thiol molecule to II may proceed via the both “concerted” and “stepwise” pathways with a rate‐determining SS bond formation step. It was found that the “concerted” pathway is slightly favorable at the enthalpy level than the “stepwise” pathway. Overall reaction (2) is found to be exothermic by 41.6 (41.4) kcal/mol. Calculations show that the MeSH bond activation by oxo species, 2_TeO, is much easier process than that by dihydroxy species, 2_Te(OH)2. Comparison of the calculated barriers for rate‐determining steps of the reaction 2_TeO + 2 MeSH with that, 19.4 (30.3) kcal/mol, for the reaction 2_TeO + H2O + 2 MeSH → 2_Te(OH)2 + MeSH indicates that in the presence of water molecule ebtellur should show less (slow) thiol reductase activity. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Structures and improvisation for inquiry‐based science instruction: A teacher's adaptation of a model of magnetism activity
Authors: Harlow Danielle Boyd 
Published: March 2009

AbstractOne aspect of scientific inquiry that appears to be particularly challenging to learn is how explanatory models are developed and used in science. It is even more challenging to learn to teach through methods that engage young students in building and using explanatory models. In part, this is because to do so requires that teachers make real‐time instructional decisions in response to the ideas that students articulate. In this paper I present an example of a teacher who participated in a series of activities during a professional development course that guided her and her colleagues through the process of developing and revising an explanatory model of magnetic phenomenon. She subsequently transformed this series of activities to use with her elementary school students. Contrasting the series of activities in the elementary classroom to the corresponding professional development activities revealed improvisational instructional acts and shed light on aspects of the classroom context that necessitated and facilitated improvisation. In particular, this paper highlights the multiple pedagogical and disciplinary structures that teachers implicitly chose among when improvising. © 2009 Wiley Periodicals, Inc. Sci Ed 94:142–163, 2010
The contested concept of sustainable aviation
Authors: Walker S. , Cook M. 
Published: March 2009

AbstractInternational passenger aviation has increased threefold in the last 25 years and is predicted to continue a similar rapid expansion over the next 25 years. While bringing considerable economic benefits, growth of the aviation sector is also likely to lead to greater adverse social and environmental impacts. To address this, sustainable aviation policy is framed as a ‘balanced strategy’. While this emphasizes the economic benefits of the aviation sector, it also aims to address the environmental and social impacts that may arise from its expansion. Other groups disagree with this interpretation of sustainable aviation, and there is little rapprochement between environmental NGOs and the aviation sector. Sustainable aviation policy is therefore contested, and different groups are attempting to reframe it to suit their own objectives. A categorization exercise supported by rhetorical, stylistic and thematic analysis was used to identify and explore the environmental discourses that are competing to construct policy for sustainable aviation. The analysis revealed that the discourse category of ecological modernization with an emphasis on environmental technology and management is dominant, that government and aviation sector attempts to achieve discursive closure through the rhetoric of ‘balance’ are failing and that sustainable aviation remains a rich discursive battleground. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment.
Free trade, fair trade and gender inequality in less developed countries
Authors: Rice Julie Steinkopf 
Published: March 2009

AbstractFair trade is often viewed as an alternative to free trade that reduces global inequality and poverty. This paper examines whether fair trade is truly an alternative to the free market, and as a consequence whether it can effectively advance gender equality and alleviate the poverty of women in less developed countries (LDCs). First, neoclassical economics and trade liberalization policies are reviewed. The paper then examines how fair trade seeks to correct market imperfections, thereby making the free market more efficient in distributing wealth. The ability of fair trade to address the central issues related to trade liberalization and women in LDCs is discussed, and the gendered structures of fair trade identified. Whether fair trade can provide gender equality within global capitalist structures is a theoretical matter that requires further empirical inquiry. Suggestions for future research, informed by feminist theories of the political economy, are provided. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment.
Can cognitive biases explain venture team homophily?
Authors: Parker Simon C. 
Published: March 2009

AbstractAlthough venture teams whose founders are dissimilar (heterophilious) tend to outperform teams whose founders are similar (homophilious), most new venture teams are characterized by homophily. I try to explain this puzzle with a learning model in which founders are prone to two cognitive biases: overoptimism and self‐serving attributions. Founders choose cofounders with similar beliefs as themselves because they expect this to promote the most effective allocation of effort to the venture. Self‐serving bias reinforces and perpetuates these beliefs. In principle, informed outsiders (e.g., practitioners or hands on investors) can improve venture team composition compared with private choices by founders. Copyright © 2009 Strategic Management Society.