bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of the Monomer 2,2′ diallylbisphenol‐A (ABFA) for obtaining Proton Exchange Membranes based on Crosslinked Sulphonated Poly(Arylene ether sulphone)s
Authors: Souza Júlio C. , Souza Carlos H. F. B. , Silva Claúdio Homero F. , Silva Maria Elisa S. R. , Sousa Ricardo G. , Freitas Roberto F. S. 
Published: October 2012

AbstractSummary: In the present work, a methodology of synthesis and characterization of the monomer 2,2′ diallylbisphenol‐A (ABFA) was developed, aiming at getting a precursor, with adequate purity, for obtaining cross‐linked membranes based on sulphonated poly(arylene ether sulphone)s. The monomer synthesis involved the synthesis of 2,2′ bis(4‐allyloxiphenyl)propane (Bisphenol‐A, diallyl ether ‐ BFAAE), from Bisphenol‐A (BFA), followed by Claisen rearrangement of BFAAE, for the production of the target compound 2,2′ diallylbisphenol‐A (ABFA). All the compounds, reagent BFA and obtained products, intermediate product BFAAE and final product ABFA, were characterized by FTIR (Fourier Transform infrared spectroscopy), TGA (Thermo‐gravimetric analysis) and HPLC (High‐performance liquid chromatography). The compound BFAAE was obtained with a yield of 94.5% and a purity of 97.3%, the latter characterized by TGA and by HPLC. The structure of the product was confirmed by FTIR. The thermal Claisen rearrangement process was conducted by using Differential Scanning Calorimetry (DSC) technique, from a factorial experiment planning, with two factors and three levels, with temperature and time being the variables. The above cited techniques were used for monitoring the Claisen rearrangement and for the characterization of the final product. The best results yield ABFA purity between 85 and 90%, approximately, for 220 °C/60min, 230 °C/30min and 210 °C/90min conditions. The obtained results suggest that, in the studied range, polymerization and degradation of the monomer ABFA occur, simultaneously to its formation.
The Effect of the Addition of Mg‐Al LDH Intercalated with Dodecyl Sulfate on the Fire Retardancy Properties of Epoxy
Authors: Becker Cristiane M. , Dick Teo A. , Ramos Jonathan T. , Wypych Fernando , Amico Sandro C. 
Published: October 2012

AbstractSummary: Layered double hydroxides (LDH) are chemical compounds that can be added to polymeric resins to confer fire retardant characteristics. The focus of this work is to study the incorporation of LDH intercalated with dodecylsulfate anions into epoxy resins. The mechanical properties were investigated using tensile, flexural and impact mechanical tests. The flame‐retardant properties were assessed using horizontal (UL 94 HB) and vertical burning (UL 94 V) tests. The highest tensile strength was obtained for the composite with 3 wt% of LDH, whereas the highest flexural strength was found by incorporating 1 wt% of LDH. All samples containing LDH showed self‐extinguishing behavior in the vertical test and lower burning rate than pristine epoxy.
PANI Conductivity: A Dependence of the Chemical Synthesis Temperature
Authors: Paschoalin Rafaella T. , Steffens Clarice , Manzoli Alexandra , Paris Elaine C. , Herrmann Paulo S. P. 
Published: October 2012

AbstractSummary: This work evaluated the influence of the synthesis temperature on the polyaniline (PANI) properties obtained by in‐situ polymerization onto a poly (terephthalate) (PET) substrate. The residual mass of these syntheses was dried under vacuum, obtaining PANI powders for each temperature investigated. PANI/PET thin films and PANI powders were characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FEG‐SEM), X‐ray diffraction (XRD), ultraviolet‐visible spectroscopy (UV‐Vis) and four‐point probe techniques. The UV‐Vis results showed that the synthesized PANI presents the emeraldine oxidation state. By means of XRD technique, it was possible to verify that the PANI powders present crystalline form. The AFM and FEG‐SEM techniques showed that the decrease in PANI/PET and PANI powders electrical conductivity with increasing of the synthesis temperature is related to the polymeric aggregates morphology.
Preparation and Cytotoxicity of Poly(Methyl Methacrylate) Nanoparticles for Drug Encapsulation
Authors: Mendes Anderson N. , Hubber Isabela , Siqueira Mônica , Barbosa Gleyce Moreno , de Lima Moreira Davyson , Holandino Carla , Pinto José Carlos , Nele Marcio 
Published: October 2012

AbstractSummary: This work aimed to produce poly(methyl methacrylate) nanoparticles for use in drug encapsulation. The polymer nanoparticles were produced using miniemulsion polymerization technique. Monomer miniemulsion showed moderate stability and polymer average particle size was about 90 nm. PMMA nanoparticles were tested for toxicity in human leukemic cell strain K562 and they did not show any adverse effect on cell viability. Therefore, poly(methyl methacrylate) nanoparticles are suitable to encapsulate antitumor agents.
Production of Poly(acrylic acid) Particles Dispersed in Organic Media
Authors: Pinto Martina C. C. , Gomes Frederico W. , Melo Caio K. , Melo Príamo A. , Castro Márcio , Pinto José Carlos 
Published: October 2012

AbstractSummary: A process for preparation of poly(acrylic acid) particles dispersed in oil is presented. The process comprises two steps: the first step involves the preparation of a poly(acrylic acid) solution, while the second step consists in the preparation of the polymer particles by dispersing the polymer solution in an organic phase. During the second step, modification of the polymer chain structure can be performed through chemical reactions. One of the advantages of the proposed process is the possibility to produce particles loaded with drugs or other chemical compounds. Besides that, if the continuous phase is vegetable oil, purification of the reaction medium may not be necessary.
An exploratory study of stalled relationships among art museum members
Authors: Reavey Brooke , Howley Michael J. , Korschun Daniel 
Published: October 2012

Museums must maintain a steady membership base to achieve their organizational objectives. Although many studies look at why relationships succeed, we examine members who fail to transition from an introductory relationship to a mature relationship with an art museum. In two studies examining non‐renewing members of a large metropolitan art museum, we find evidence for a phenomenon we call “stalled” relationships, whereby members discontinue their formal museum membership yet maintain a positive psychological affiliation with the museum. Our first study finds that members in stalled relationships often do not view themselves as defectors and do not blame the museum for their non‐renewal; they frequently cite personal reasons rather than service failures for discontinuing their membership. Our second study examines this phenomenon in greater detail, exploring the antecedents for stalling and finds that motivations for initiating their membership may help predict when a relationship is likely to stall.Copyright © 2012 John Wiley & Sons, Ltd.
Co‐creating nonprofit brand equity
Authors: Juntunen Mari , Juntunen Jouni , Autere Vesa 
Published: October 2012

The concept of brand equity (BE) has been the subject of much recent discussion in the field of nonprofit branding and also has been the concept of brand co‐creation in the field of branding. This study combines these aspects and examines the BE co‐creation of a nonprofit entity, the Finnish Defence Forces military driving school. Empirical data were collected from industrial logistics service providers and military recruits. A theoretical BE model was further developed using structural equation modeling in an exploratory manner to reveal whether the BE model of the military driving school is similar from both viewpoints. Similar workable models were found, indicating strong BE co‐creation and thereby contributing to the field. To support the future co‐creation of BE of the military driving school, it is important to ensure that the recruits take positive experiences from the school and industrial logistics service providers carefully consider how they relay their experiences about the school to other truck drivers. The attitudes of recruits towards the military driving school are likely eventually to conform to those of civilian truck drivers. Finding workable models required omitting some BE dimensions and measures of earlier models. Moreover, using data from one country alone may be a limitation of the study. Therefore, nonprofit BE measures should be further developed and tested with data from further afield.Copyright © 2012 John Wiley & Sons, Ltd.
Characterizing antiprion compounds based on their binding properties to prion proteins: Implications as medical chaperones
Authors: Kamatari Yuji O. , Hayano Yosuke , Yamaguchi Kei‐ichi , Hosokawa‐Muto Junji , Kuwata Kazuo 
Published: October 2012

AbstractA variety of antiprion compounds have been reported that are effective in ex vivo and in vivo treatment experiments. However, the molecular mechanisms for most of these compounds remain unknown. Here we classified antiprion mechanisms into four categories: I, specific conformational stabilization; II, nonspecific stabilization; III, aggregation; and IV, interaction with molecules other than PrPC. To characterize antiprion compounds based on this classification, we determined their binding affinities to PrPC using surface plasmon resonance and their binding sites on PrPC using NMR spectroscopy. GN8 and GJP49 bound specifically to the hot spot in PrPC, and acted as “medical chaperones” to stabilize the native conformation. Thus, mechanisms I was predominant. In contrast, quinacrine and epigallocathechin bound to PrPC rather nonspecifically; these may stabilize the PrPC conformation nonspecifically including the interference with the intermolecular interaction following mechanism II. Congo red and pentosan polysulfate bound to PrPC and caused aggregation and precipitation of PrPC, thus reducing the effective concentration of prion protein. Thus, mechanism III was appropriate. Finally, CP‐60, an edarabone derivative, did not bind to PrPC. Thus these were classified into mechanism IV. However, their antiprion activities were not confirmed in the GT + FK system, whose details remain to be elucidated. This proposed antiprion mechanisms of diverse antiprion compounds could help to elucidate their antiprion activities and facilitate effective antiprion drug discovery.
Defect generation, advanced crystallization, and characterization methods for high‐quality solar‐cell silicon
Authors: Di Sabatino Marisa , Stokkan Gaute 
Published: October 2012

AbstractSilicon is the dominant material for production of solar cells. Research work constantly aims at improving the quality of the silicon materials to achieve higher solar‐cell conversion efficiencies. It has been demonstrated that defects and impurities, often rising during the silicon ingot production and due to the presence of impurity sources throughout the silicon solar‐cell value chain (e.g. silicon feedstock, crucible and coating, furnace atmosphere, etc.), have a detrimental effect on device performances. Crystallization is the first step in the solar‐cell value chain. During crystallization, crystal defects, such as grain boundaries and dislocations, develop, and impurities, such as dopants and metals, distribute. By controlling the process, we can also control the defect formation and impurity segregation. In this study, we review some of the work carried out at NTNU to understand the role of defects and impurities on materials properties. Specifically, we report on some of the work done on defects, crystallization, and characterization.
Structure and stability of coiled carbon nanotubes
Authors: Milošević Ivanka , Popović Zoran P. , Damnjanović Milan 
Published: October 2012

AbstractHelically coiled carbon nanotubes are modeled using topological coordinate method which is based on the toroidal triply connected graphs, containing pentagons, hexagons, and heptagons. Their regular incorporation into the hexagonal carbon net induces transition from the straight to the helical geometry. Relaxation of the structural model is performed in two steps: Firstly, molecular dynamics based on the Brenner potential is applied and then the coil parameters are, once again, optimized within symmetry preserving density functional tight binding (DFTB) method. Model of smooth regularly helically coiled single‐walled nanotube structure is obtained. Correlations between the helical angle, tubular and helical diameter are found. Cohesive energy of the coiled structure is calculated by DFTB method within symmetry based POLSym code. Its dependence on the diameter of the coil is shown. The calculated energies range from 7.5 to 8.0 eV/atom.
Controlling edge states in the Kane–Mele model via edge chirality
Authors: Autès Gabriel , Yazyev Oleg V. 
Published: October 2012

Abstractmagnified imageWe investigate the dependence of band dispersion of the quantum spin Hall effect (QSHE) edge states in the Kane–Mele model on crystallographic orientation of the edges. Band structures of the one‐dimensional honeycomb lattice ribbons show the presence of the QSHE edge states at all orientations of the edges given sufficiently strong spin–orbit interactions. We find that the Fermi velocities of the QSHE edge‐state bands increase monotonically when the edge orientation changes from zigzag (chirality angle $ \theta = 0^\circ $) to armchair ($ \theta = 30^\circ $). We propose a simple analytical model to explain the numerical results. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Topological surface states of Bi2Se3 coexisting with Se vacancies
Authors: Yan Binghai , Zhang Delin , Felser Claudia 
Published: October 2012

Abstractmagnified imageAlthough topological surface states are known to be robust against nonmagnetic surface perturbations, their band dispersions and spatial distributions are still sensitive to surface defects. Taking Bi2Se3 as an example, we demonstrate that Se vacancies modify the surface band structures considerably. When large numbers of Se vacancies exist on the surface, topological surface states may sink down from the first to the second quintuple layer and get separated from the vacancies. We simulated scanning tunnelling microscopy images to distinguish surfaces with Se and Bi terminations.magnified image(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Robot assisted surgery in gynaecologic oncology – starting a program and initial learning curve from a UK tertiary referral centre: the Guildford perspective
Authors: Madhuri Thumuluru Kavitha , Hamzawala Imran , Tailor Anil , Butler‐Manuel Simon 
Published: October 2012

AbstractBackgroundThe paper discusses the setup and evaluation of early data following the establishment of a robotic surgery programme in a UK gynaecological oncology cancer centre.MethodsProspective data were collected between December 2009 and December 2011 for all women undergoing robotic assisted procedures within the gynaecological oncology department. Patient demographics, intra, peri and post‐operative data were collected at a single institution, which is a tertiary referral centre for gynaecological oncology and minimal access surgery.ResultsIn total, 104 robotically assisted cases were performed within the gynaecological oncology team. The procedures undertaken included simple and radical hysterectomy, radical trachelectomy, BSO following previous hysterectomy, pelvic and para‐aortic node dissection and omentectomy. The mean blood loss was 155.24 mL and the mean hospital stay was 3 days with more than half the women being discharged on day 1 post surgery.ConclusionsThese data suggest that robotic assisted surgery is well suited to treating women with principally endometrial and cervical cancers and selected cases of ovarian cancer, enabling surgical staging to be completed with many more patients benefitting from a minimal access surgery approach. Thorough preparation, appropriate case selection and preceptorship in robotic surgery is essential to minimize the associated risks associated with adopting new surgical techniques. Copyright © 2012 John Wiley & Sons, Ltd.
Corporate Social Responsibility of the Financial Sector – Strengths, Weaknesses and the Impact on Sustainable Development
Authors: Weber Olaf , Diaz Michael , Schwegler Regina 
Published: October 2012

ABSTRACTThis study analyses the performance of the financial sector with respect to corporate social responsibility and sustainability. Because this sector has a strong influence economically and on sustainable development, both risk management issues and stakeholder pressure drive the financial sector into a more sustainable direction. In contrast to polluting sectors, the financial sector does not affect the environment and society by direct emissions or the use of resources like other industries. To compare the financial sector with other sectors regarding their sustainability performance, we analyzed the performance in the fields of sustainability reporting, business ethics and product responsibility, labor issues, environmental performance, community issues, and corporate governance. The study is based on more than 1800 firms including 400 organizations from the financial sector. We link CSR to sustainability and define it as corporate self‐regulation in order to manage sustainability risks and opportunities. The results suggest that financial sector performance is relatively low regarding corporate social responsibility (CSR) in general. Weaknesses of the financial sector with regard to CSR are reporting, business ethics and product responsibility, and labor issues. Strengths of the financial sector regarding CSR can be located with respect to community relations. Further research is needed with respect to the factors influencing CSR performance. It is still not clear what influences regulations, stakeholder pressure or potential financial benefits have on sustainability performance in the financial sector. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.
Pedagogical content knowledge as reflected in teacher–student interactions: Analysis of two video cases
Authors: Alonzo Alicia C. , Kobarg Mareike , Seidel Tina 
Published: October 2012

AbstractDespite the theorized centrality of pedagogical content knowledge (PCK) for teaching, we have little evidence of the relationship between PCK and students' learning and know relatively little about how to help teachers to develop PCK. This study is a preliminary attempt to address these gaps in our knowledge of PCK through exploration of two German physics teachers' classroom instruction in consecutive lessons on optics. We show how video analysis can be used to gather evidence for one aspect of teachers' PCK: their use of content knowledge in interactions with students. We identify three potentially important characteristics of this aspect of PCK: flexibility, richness, and learner‐centeredness. By contrasting teachers with high and low gains in student knowledge and interest, we explore potential mechanisms by which this aspect of PCK might affect student outcomes. Because German teacher preparation programs emphasize content more than pedagogical knowledge, these cases contribute to our understanding of the support that teachers with strong content knowledge may need in translating this knowledge into a form useful for teaching.Fachdidaktisches Wissen ist aus theoretischer Sicht besonders zentral für das Unterrichten. Aus empirischer Sicht gibt es bislang allerdings noch wenig Evidenz für den Einsatz fachdidaktischen Wissens während des Unterrichtens und seine Bedeutung für das Lernen von Schülerinnen und Schülern. Außerdem wissen wir wenig darüber, wie Lehrpersonen über die Zeit fachdidaktisches Wissen entwickeln. Diese Studie ist ein Versuch, diese Wissenslücken zum fachdidaktischen Wissen von Lehrpersonen zu bearbeiten. Dabei wird exemplarisch der Unterricht von zwei deutschen Physiklehrern in aufeinanderfolgenden Stunden zum Thema Optik untersucht. Die Studie zeigt wie Videoanalysen genutzt werden können, um Belege für einen Aspekt des fachdidaktischen Wissens der Lehrpersonen zu sammeln: Ihre Nutzung von inhaltlichem Wissen in der Interaktion mit den Schülerinnen und Schülern. In dieser Studie werden drei potentiell wichtige Charakteristika dieses Aspekts des fachdidaktischen Wissens identifiziert: Flexibilität, Reichhaltigkeit und Schülerorientierung. Durch die Gegenüberstellung von Lehrpersonen mit hohem und niedrigem Wissens‐ und Interessenzuwachs wurden potentielle Mechanismen untersucht, durch die dieser Aspekt des fachdidaktischen Wissens die Lernergebnisse von Schülerinnen und Schülern beeinflussen kann. Die Lehrerausbildung in Deutschland betont das inhaltliche Wissen stärker als das fachdidaktische Wissen. Die ausgewählten Fälle beschreiben, welche Unterstützung Lehrpersonen mit einem hohen fachlichen Wissen benötigen, um dieses Wissen so zu verändern, dass es für das Unterrichten genutzt werden kann. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 1211–1239, 2012
From the contribution to the action approach: White teachers' experiences influencing the development of multicultural science curricula
Authors: Suriel Regina L. , Atwater Mary M. 
Published: October 2012

AbstractIn this exploratory case study, we sought to understand teacher's integration of multicultural curricula in science curriculum units, and how personal experiences influenced the level of integration in light of Bank's typology of ethnic content integration into school curricula. Five research participants volunteered and were selected so as to be representative of the demographic of pre‐service and in‐service teachers in the southern United States. The aim was to explore teachers' personal experiences with cultural others that either facilitated or impeded their adoption of multicultural curricula strategies in science curricula units. Case narratives present and discuss interview data and assigned curricula projects. Findings suggest that participants who had transformative cultural experiences and who identified as the marginalized cultural other, transformed science curricula at higher levels of Bank's typology for curricula' multicultural approaches. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 1271–1295, 2012
Service provided by fading MIMO channels: a deterministic perspective
Authors: Dong Yunquan , Fan Pingyi , Letaief Khaled Ben 
Published: October 2012

ABSTRACTIn this paper, we study the channel service process of a multiple‐input multiple‐output (MIMO) system over an independent and identically distributed (i.i.d.) fading channel. One key problem of communication over fading MIMO channels is what kind of service the MIMO channel can provide. In this paper, this problem is investigated in terms of channel service process. Assuming that the channel state information is available at the receiver, the channel service process S(t) is defined as the integral of the instantaneous channel capacity over a time interval of length t, which specifies the service provided by the channel during the period. Using the characteristic function approach and the infinitely divisible law, it is proved that the channel service process S(t) is a deterministic linear function of time t, other than any curve form or a stochastic process. Specifically, , where is a constant equal to the corresponding ergodic capacity. This result has two implications: (i) i.i.d. fading MIMO channels can support a constant rate traffic stream of rate without higher layer transmission delay; (ii) the ergodic capacity is the actual transmission capacity of the fading channel, other than only a statistical average value. Copyright © 2012 John Wiley & Sons, Ltd.