bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionomer‐based polyurethanes: a comparative study of properties and applications
Authors: Jaudouin Olivier , Robin Jean‐Jacques , Lopez‐Cuesta José‐Marie , Perrin Didier , Imbert Claire 
Published: February 2012

AbstractPolyurethanes cover a large range of materials exhibiting various physical and mechanical properties making them useful in different applications such as elastomers or biomaterials, for instance. The introduction of ionic groups in the polyurethane backbone opens the way to new applications where the ionic groups can act as physical crosslinkers that greatly modify the final mechanical and thermal properties of the materials. Furthermore, the hydrophilicity of the chains can be enhanced by the presence of the ionic species, and so the materials can be processed as conventional dispersions even in a polar solvent such as water. As a consequence the applications are numerous; the main commercial outlets are focused on coatings and textiles industries where they can be used as waterproof coatings or substitutes for leather. But these materials can also be used in high‐tech industries for shape memory materials, biomedical devices and biocompatible materials. This review summarizes the latest developments of this class of promising materials and provides the reader with the potentialities of these polymers in various areas.
Crystalline thin‐foil silicon solar cells: where crystalline quality meets thin‐film processing
Authors: Dross Frederic , Baert Kris , Bearda Twan , Deckers Jan , Depauw Valerie , El Daif Ounsi , Gordon Ivan , Gougam Adel , Govaerts Jonathan , Granata Stefano , Labie Riet , Loozen Xavier , Martini Roberto , Masolin Alex , O'Sullivan Barry , Qiu Yu , Vaes Jan , Van Gestel Dries , Van Hoeymissen Jan , Vanleenhove Anja , Van Nieuwenhuysen Kris , Venkatachalam Srisaran , Meuris Marc , Poortmans Jef 
Published: February 2012

ABSTRACTCrystalline Si (c‐Si) technology is dominating the photovoltaics market. These modules are nonetheless still relatively expensive, in particular because of the costly silicon wafers, which require large thickness mostly to ease handling. Thin‐film technologies, on the other hand, use much less active material, exhibit a much lower production cost per unit area, but achieve an efficiency still limited on module level, which increases the total system costs. A meet‐in‐the‐middle is possible and is the object of this paper. The development of c‐Si thin‐foil modules is presented: first, the fabrication of the active material on a glass module and then the processing of the Si foils into solar cells, directly on module level. The activity of IMEC in this area is put into perspective with regard to worldwide research results. It appears that great opportunities are offered to this cell concept, although some challenges still need to be tackled before cost‐effective and reliable industrial production can be launched. Copyright © 2012 John Wiley & Sons, Ltd.
Losses produced by soiling in the incoming radiation to photovoltaic modules
Authors: Zorrilla‐Casanova José , Piliougine Michel , Carretero Jesús , Bernaola‐Galván Pedro , Carpena Pedro , Mora‐López Llanos , Sidrach‐de‐Cardona Mariano 
Published: February 2012

ABSTRACTThe accumulation of dust on the surface of a photovoltaic module decreases the radiation reaching the solar cell and produces losses in the generated power. Dust not only reduces the incoming radiation on the solar cell but also changes the dependence on the angle of incidence of such radiation. This work presents the results of a study carried out at the University of Malaga to quantify radiation losses caused by soiling on the surface of photovoltaic modules. Our results show that the mean of the daily irradiation losses in a year caused by dust deposited on the surface of a photovoltaic module is around 4%. After long periods without rain, daily irradiation losses can be higher than 20%. In addition, the irradiance losses are not constant throughout the day, and they are strongly dependent on the angle of incidence and the ratio between diffuse and direct radiations. The irradiance losses as a function of solar time are symmetric with respect to noon, where they reach the minimum value. We also propose a simple theoretical model that describes the qualitative behaviour of the irradiance losses during the day. This model takes into account the percentage of dirty surface and the diffuse/direct irradiance ratio. Copyright © 2012 John Wiley & Sons, Ltd.
Multi‐dimensional modeling of solar cells with electromagnetic and carrier transport calculations
Authors: Li Xiaofeng , Hylton Nicholas P. , Giannini Vincenzo , Lee Kan‐Hua , Ekins‐Daukes Ned J. , Maier Stefan A. 
Published: February 2012

ABSTRACTWe present a multi‐dimensional model for comprehensive simulations of solar cells (SCs), considering both electromagnetic and electronic properties. Typical homojunction and heterojunction gallium arsenide SCs were simulated in different spatial dimensions. When considering one‐dimensional problems, the model performs carrier transport calculations following a Beer–Lambert optical absorption approximation. We show that the results of such simulations exhibit excellent agreement with the standard PC1D one‐dimensional photovoltaic simulation. Photonic and plasmonic attempts to enhance SC efficiency demand comprehensive electromagnetic calculations to be undertaken in order to acquire accurate carrier generation profiles in two and three‐dimensional systems. Our model provides complete spectral and spatial information of typical optical and electronic behavior. Furthermore, our approach permits the detailed investigation of complex systems, including plasmonic SCs, which cannot be simulated using low‐dimensional modeling tools. We present the results of numerical simulations of an optically thin plasmonic gallium arsenide SC and observe improved device performance arising from the application of plasmonic nanostructures, which agree well with previous experimental findings. Copyright © 2012 John Wiley & Sons, Ltd.
Nanospace preparation by crosslinking helical syndiotactic‐poly(methacrylic acid) in acetonitrile/water after stereocomplexation
Authors: Ajiro Hiroharu , Maegawa Masumi , Akashi Mitsuru 
Published: February 2012

AbstractVarious molecular weights of isotactic (it‐)‐poly(methyl methacrylate) (PMMA) and syndiotactic (st‐)‐poly(methacrylic acid) (PMAA) were used to form an it‐PMMA/st‐PMAA (1/2) stereocomplex in acetonitrile/water as a suspension. The stereocomplex was tentatively crosslinked with 1,11‐diamino‐3‐6‐9‐trioxaundecane and water soluble carbodiimide at 10, 20, and 40 mol % concentrations versus MAA unit. The it‐PMMA was extracted from the crosslinked stereocomplex under alkaline conditions, and the successive re‐incorporation of the it‐PMMA was carried out. During the extraction and re‐incorporation processes, the FTIR/ATR spectra showed the absence and generation of a peak at 860 cm−1, respectively, which was characteristic of this stereocomplex. The result of the XRD analysis also corresponded with the extraction and re‐incorporation behavior of it‐PMMA; peaks were observed at 2θ = 12 and 15°, d = 0.74 and 0.59 nm, respectively. This study showed that the nanospaces of helical st‐PMAA were available in acetonitrile/water in a suspended state using a crosslinking approach. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Control of helical chirality of poly(quinoxaline‐2,3‐diyl)s based on postpolymerization modification of the terminal group by small chiral molecules
Authors: Nagata Yuuya , Ohashi Satoru , Suginome Michinori 
Published: February 2012

AbstractPoly(quinoxaline‐2,3‐diyl)s having a terminal formyl or boronyl group were prepared by living polymerization of 1,2‐diisocyanobenzenes using organopalladium initiators bearing a protected formyl or boronyl group. Poly(quinoxaline‐2,3‐diyl)s were successfully deracemized by reacting them with small optically active molecules at their terminal formyl or boronyl group, leading to the induction of optically active helical structures. Poly(quinoxaline‐2,3‐diyl) having terminal formyl groups was converted to one‐handed helical polymer, in which the screw‐sense excess was 68% (84:16). The helix sense of the boronyl‐terminated poly(quinoxaline‐2,3‐diyl) was reversibly controlled by attaching and removing the chiral group. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Reduction of current collapse in the multi‐mesa‐channel AlGaN/GaN HEMT
Authors: Ohi Kota , Hashizume Tamotsu 
Published: February 2012

AbstractTransport properties and off‐stress‐induced current collapse characteristics of the multi‐mesa‐channel (MMC) AlGaN/GaN HEMTs were investigated. The surrounding field effect in the MMC structure led to a shallower threshold voltage and a smaller subthreshold slope compared to those of the conventional planar HEMT. After applying off‐state bias stress, the planar HEMT showed remarkable current collapse, including significant increase in on‐resistance increasing the drain stress bias. On the other hand, for the MMC HEMT, we observed less change in on‐resistance (RON) even after the application of high drain bias stress. This shows that the MMC structure has resistance to the off‐stress‐induced current collapse. In the case of a mesa‐top width (Wtop) of less than 100 nm, the channel resistance of the MMC HEMT is estimated to be about one order of magnitude higher than the increase in access resistance induced by the off‐state stress. It is thus likely that the operation of the MMC HEMT is rather insensitive to change in access resistance. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluating raw ensembles with the continuous ranked probability score
Authors: Bröcker Jochen 
Published: February 2012

AbstractThe continuous ranked probability score (CRPS) is a frequently used scoring rule. In contrast with many other scoring rules, the CRPS evaluates cumulative distribution functions. An ensemble of forecasts can easily be converted into a piecewise constant cumulative distribution function with steps at the ensemble members. This renders the CRPS a convenient scoring rule for the evaluation of ‘raw’ ensembles, obviating the need for sophisticated ensemble model output statistics or dressing methods prior to evaluation. In this article, a relation between the CRPS score and the quantile score is established. The evaluation of ‘raw’ ensembles using the CRPS is discussed in this light. It is shown that latent in this evaluation is an interpretation of the ensemble as quantiles but with non‐uniform levels. This needs to be taken into account if the ensemble is evaluated further, for example with rank histograms. Copyright © 2012 Royal Meteorological Society
Wanted: dead or alive? Isotopic analysis (δ13C and δ15N) of Pygoscelis penguin chick tissues supports opportunistic sampling
Authors: Vasil Christopher A. , Polito Michael J. , Patterson William P. , Emslie Steven D. 
Published: February 2012

RATIONALEPhysiological stress and starvation have been shown to affect δ13C and δ15N isotope values and, given that animals often die from starvation, the cause of death may be an important factor to consider in stable isotope analyses of opportunistically collected samples.METHODSWe addressed this issue by comparing tissue stable isotope values of living and deceased Adélie (Pygoscelis adeliae) and Chinstrap Penguin (P. antarctica) chicks collected from the same respective populations.RESULTSNo significant difference was found between living and deceased penguin chick feather, down, and toenail isotope values and both groups displayed similar isotopic trends between tissue types. In addition, similar relationships were observed between both species and across several seasons. Furthermore, sub‐dermal adiposity and cause of death (starvation and/or predation) had no significant effect on the δ13C and δ15N values.CONCLUSIONSOur findings suggest that tissues from deceased penguins can be isotopically representative of tissues obtained from the living population, despite the cause of death, and support the use of opportunistic sampling in stable isotope analyses. Copyright © 2012 John Wiley & Sons, Ltd.
Using stable isotope analysis to discriminate gasoline on the basis of its origin
Authors: Heo Su‐Young , Shin Woo‐Jin , Lee Sin‐Woo , Bong Yeon‐Sik , Lee Kwang‐Sik 
Published: February 2012

RATIONALELeakage of gasoline and diesel from underground tanks has led to a severe environmental problem in many countries. Tracing the production origin of gasoline and diesel is required to enable the development of dispute resolution and appropriate remediation strategies for the oil‐contaminated sites.METHODSWe investigated the bulk and compound‐specific isotopic compositions of gasoline produced by four oil companies in South Korea: S‐Oil, SK, GS and Hyundai. The relative abundance of several compounds in gasoline was determined by the peak height of the major ion (m/z 44).RESULTSThe δ13CBulk and δDBulk values of gasoline produced by S‐Oil were significantly different from those of SK, GS and Hyundai. In particular, the compound‐specific isotopic value (δ13CCSIA) of methyl tert‐butyl ether (MTBE) in S‐Oil gasoline was significantly lower than that of gasoline produced by other oil companies. The abundance of several compounds in gasoline, such as n‐pentane, MTBE, n‐hexane, toluene, ethylbenzene and o‐xylene, differed widely among gasoline from different oil companies.CONCLUSIONSThis study shows that gasoline can be forensically discriminated according to the oil company responsible for its manufacture using stable isotope analysis combined with multivariate statistical analysis. Copyright © 2012 John Wiley & Sons, Ltd.
Differentiation of two industrial oil sands process‐affected waters by two‐dimensional gas chromatography/mass spectrometry of diamondoid acid profiles
Authors: Rowland Steven J. , West Charles E. , Scarlett Alan G. , Ho Cheuk , Jones David 
Published: February 2012

RATIONALEProcessing of the oil sands of Canada has produced large amounts of process‐affected water (OSPW). Concerns have been raised over the possible environmental impacts of any leakage of OSPW from storage lagoons which contain toxicants, including organic acids. Natural weathering of oil sands deposits may also produce the toxicants, including the acids. Therefore, there is a need for differentiation of the possible natural and industrial sources of such toxicants and also for methods suitable for monitoring changes in the composition of OSPW during long‐term storage.METHODSHere we show in a simple preliminary study of the two samples currently available to us, by use of comprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry (GCxGC/ToF‐MS), the distributions of methyl esters of individual isomeric diamondoid acids in OSPW from lagoons with different histories and from different industrial operators.RESULTSWe show that the distributions of methyl esters of individual isomeric diamondoid acids, including methyladamantane carboxylic and ethanoic acids, identified by comparison with data for reference compounds, can be differentiated readily. The use of acids with known structures, each verified by authentic acids, known toxicities and known and/or predictable physicochemical properties, to distinguish the different sources is advantageous, since factors likely to control the fate and dispersion of the acids can then more easily be predicted. It is postulated that the differences observed in the relative amounts of some of the acids result from variable extents of bacterial transformation of the organic matter in OSPW.CONCLUSIONSThe differences in distributions of diamondoid acids clearly vary between the two samples of OSPW and may prove very useful for monitoring the fate of different sources of OSPW both in storage and in the wider environment, once a wider collection of representative samples is available for study. Copyright © 2012 John Wiley & Sons, Ltd.
Public key encryption supporting plaintext equality test and user‐specified authorization
Authors: Tang Qiang 
Published: February 2012

ABSTRACTIn this paper, we investigate a category of public key encryption schemes that supports plaintext equality test and user‐specified authorization. With this new primitive, two users, who possess their own public/private key pairs, can issue token(s) to a proxy to authorize it to perform plaintext equality test from their ciphertexts. We provide a formal formulation for this primitive and present a construction with provable security in our security model. To mitigate the risks against the semi‐trusted proxies, we enhance the proposed cryptosystem by integrating the concept of computational client puzzles. As a showcase, we construct a secure personal health record application on the basis of this primitive. Copyright © 2012 John Wiley & Sons, Ltd.
Conventional and advanced bending strength analysis of common and castellated, homogeneous and hybrid I‐beams
Authors: Chróścielewski Jacek , Cywiński Zbigniew , Sitarski Arkadiusz 
Published: February 2012

AbstractAn appropriate investigation has been performed in order to estimate the bending strength safety of steel I‐beams typical in traditional and up‐to‐date computational analyses. The bending strengths of the conventional analysis have been set in general form for the beam parameters of the span/depth ratios usually observed. Mutual strength relationships between common and castellated, homogeneous and hybrid I‐beams, reflect the anticipated regularities. Use of the advanced analysis, founded on the non‐linear FEM approach, required the solution of adequate practical examples. In view of the research class, certain completion of the typical non‐linear procedure was needed.Konventionelle und verschärfte Berechnung der Biegefestigkeit normaler und wabenförmiger, homogener und hybrider I‐Träger. Um die Biegefestigkeit von stählernen I‐Trägern abzuschätzen, typischer Bestandteil traditioneller und moderner Berechnungsverfahren, wurde eine entsprechende Untersuchung unternommen. Für die üblichen Bauteilparameter der Spannweite/Höhe‐Verhältnisse wurden die Biegefestigkeiten der konventionellen Berechnung in der allgemeinen Form festgesetzt. Die ermittelten Traglastverhältnisse zwischen den normalen und wabenförmigen, homogenen und hybriden I‐Trägern gaben die erwarteten Verhältnisse wieder. Die Anwendung der verschärften Berechnungsmethode, gestützt auf dem nichtlinearen Vorgehen der FEM, bedurfte der Lösung entsprechender praktischer Beispiele. Angesichts der Untersuchungsklasse war eine Ergänzung des typischen nichtlinearen Verfahrens nötig.
Ersatzneubau der Autobahnbrücke über den Havelkanal bei Brieselang
Authors: Degenhardt‐Herberger Kay , Reinke Klaus‐Dieter 
Published: February 2012

AbstractDie Autobahn A10 wird im westlichen Teil des Berliner Rings in der Nähe der Ortschaft Brieselang über den Havelkanal geführt. Ein Konstruktionsfehler in der Lagerung erforderte den Ersatz des bestehenden Bauwerkes. Für den Ersatzneubau wurde insbesondere unter Berücksichtigung wirtschaftlicher und gestalterischer Aspekte eine Ausführung in Form einer Netzwerkbogenbrücke mit Radialnetz als beste Lösung für den Brückenschlag gefunden. Der Bericht befasst sich mit Aspekten des Bauwerksentwurfes, der Ausschreibung und Vergabe sowie der Bauausführung des im November 2011 fertiggestellten Brückenbauwerkes.Reconstruction of the motorway bridge over the Havelkanal near Brieselang, Germany. The motorway A10 is routed over the Havelkanal in the western part of the Berliner Ring, a perimeter road, close to the small town of Brieselang. Due to a constructional fault of the bearings the replacement of the old bridge became necessary. Considering all economic and design aspects, a network arch bridge with radial net was chosen as most suitable solution. The paper discusses aspects of conceptual design, tendering and contracting as well as the construction work of the new bridge completed in November 2011.
Combined effect of hindered amine light stabilizer and ultraviolet absorbers on photodegradation of poly(vinyl chloride)
Authors: Chai Ruidan , Chen Shuangjun , Zhang Jun 
Published: February 2012

AbstractThe combined effect of a basic hindered amine light stabilizer (HALS) and ultraviolet absorbers (UVAs) on casted poly(vinyl chloride) (PVC) films, during photodegradation, was studied by color change, ultraviolet‐visible (UV–vis) spectroscopy, Fourier‐transform infrared (FTIR) spectroscopy, and viscosity‐average molecular weight. It was found that the basic amine groups in the HALS (T770) could promote the dehydrochlorination, thereby accelerating the photooxidation of PVC films. Meanwhile, T770 could scavenge the radicals formed and restrain the aging of PVC to some extent. The above‐mentioned aspects were competing factors: the former played a dominant role during the first 100 h, while the latter counteracted the former effect to some extent between 100 and 300 h. A benzotriazole derivative (UV326) absorbs more UV radiation in the UV‐A region (320–400 nm), which mainly causes the photodegradation of PVC samples, than a benzophenone derivative (UV531). Thus, UV326 is a more efficient UV absorber than UV531 in prohibiting the photooxidation and chain scission of PVC films. The combination of T770 and UV326 effectively protected PVC films from dehydrochlorination and photooxidation. The combination of T770 and UV531 accelerated the dehydrochlorination and discoloration of PVC films. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers
Effects of polymerization catalyst technology on the melt processing stability of polyethylenes. part 2. single stabilizer performance
Authors: del Teso Sánchez Karmele , Allen Norman S. , Liauw Christopher M. , Edge Michelle , Johnson Brian , Catalina Fernando , Corrales Teresa 
Published: February 2012

AbstractThe effects of a range of thermal and light stabilizers on the melt stability (investigated via multiple pass extrusion) and color stability of three different polyethylenes (PEs) were examined. The PEs varied in terms of the catalyst system used to synthesize the polymers and included an HDPE produced by using a chromium‐based Phillips catalyst and two LLDPEs produced via chromium‐based metallocene and titanium‐based Ziegler‐Natta catalysts. The additive types included a range of phenolics of different functionality, phosphites, hindered piperidines, an hydroxylamine, and Vitamin E. The results obtained for the three PEs confirmed that primary antioxidants (AOs) such as highly hindered and less, hindered phenols or hydroxylamines promoted good melt stability but in some cases tended toward yellowing. The secondary AOs such as the phosphites or thioethers behaved in the opposite way; color suppression was good, but melt stabilization was poor. It was also shown that for different types of phenols (all with similar molar activity), reducing steric hindrance to the phenolic OH enhanced the tendency to form chromophoric groups and hence color led to better efficiency than high hindrance. Those phenol with higher molar activity (mol OH/kg AO) showed the best processing performance. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers