bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Photocatalysts for Surface Hybridization of TiO2 Nanofibers with Carbon Films
Authors: Chang Guoqing , Cheng Zhen , Warren Roseanne , Song Guoxia , Shen Jianyi , Lin Liwei
Published: February 2015

Titania (TiO2) modification with carbon nanolayers to increase substrate adsorption in the vicinity of the photocatalytic sites and high migration efficiency of photoinduced electrons at the carbon/TiO2 interface lead to a photocatalyst with enhanced efficiency. Herein, surface hybridization with carbon nanolayers of continuous TiO2 nanofibers based on the electrospinning technique were fabricated. Compared with TiO2 nanofibers, the photocatalyst of carbon‐layer‐covered TiO2 nanofibers presented a higher photocatalytic activity under UV irradiation for the degradation of organic compounds (methylene blue). The photostability was retained after five cycles under UV irradiation.
Radiopharmaceuticals for assessing ABC transporters at the blood–brain barrier
Authors: Raaphorst RM , Windhorst AD , Elsinga PH , Colabufo NA , Lammertsma AA , Luurtsema G
Published: February 2015

ABC transporters protect the brain by transporting neurotoxic compounds from the brain back into the blood. P‐glycoprotein (P‐gp) is the most investigated ABC (efflux) transporter, as it is implicated in neurodegenerative diseases such as Alzheimer's disease. Altered function of P‐gp can be studied in vivo, using Positron Emission Tomography (PET). To date, several radiopharmaceuticals have been developed to image P‐gp function in vivo. So far, attempts to image expression levels of P‐gp using radiolabeled P‐gp inhibitors have not been successful. Improved knowledge of compound behavior toward P‐gp from in vitro studies should increase predictability of in vivo outcome.
Superior Capacitive Performance of Hydrochar‐Based Porous Carbons in Aqueous Electrolytes
Authors: Fuertes Antonio B. , Sevilla Marta
Published: February 2015

Biomass‐based highly porous carbons with excellent performances in aqueous electrolyte‐based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass‐based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g−1 in H2SO4 and >190 F g−1 in Li2SO4). Additionally, the mesopores present in the melamine‐based micro‐/mesoporous carbons notably improve the ion‐transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2SO4.
Nearly monotonic passband low‐pass filter design by using sum‐of‐squared Legendre polynomials
Authors: Živaljević Dragana , Stamenković Negovan , Stojanović Vidosav
Published: February 2015

A new type of filter approximation, which utilizes orthonormal Legendre polynomials, referred to as sum‐of‐squared Legendre polynomials, is presented in this paper. Power transmission coefficient and the group delay of the proposed filter are compared with those of the Butterworth, Legendre–Papoulis, and Halpern filters. In order to illustrate the design of the proposed filter function, sum‐of‐squared Legendre polynomials coefficients and normalized element values of the low‐pass LC (inductor‐capacitor) ladder network prototype are given, up to the 10th degree. For continuous‐time domain filtering, doubly terminated LC ladder network topologies have very low sensitivities to changes of component values. In order to determine the effect of variation of all reactive components on the filter attenuation characteristic, the new sensitivity function has been proposed. Copyright © 2015 John Wiley & Sons, Ltd.
Gaussian integers and interleaved rank codes for space–time block codes
Authors: Asif H. M. , Honary B. , Hamayun M. T.
Published: February 2015

This paper presents the design of space–time block codes (STBCs) over maximum rank distance (MRD) codes, energy‐efficient STBCs, STBCs using interleaved‐MRD codes, the use of Gaussian integers for STBCs modulation, and Gabidulin's decoding algorithm for decoding STBCs. The design fundamentals of STBCs using MRD codes are firstly put forward for different number of transmit antennas. Extension finite fields (Galois fields) are used to design these linear block codes. Afterward, a comparative study of MRD‐based STBCs with corresponding orthogonal and quasi‐orthogonal codes is also included in the paper. The simulation results show that rank codes, for any number of transmit antennas, exhibit diversity gain at full rate contrary to orthogonal codes, which give diversity gain at full rate only for two transmit antennas case. Secondly, an energy‐efficient MRD‐STBC is proposed, which outperforms orthogonal STBC at least for 2 × 1 antenna system. Thirdly, interleaved‐MRD codes are used to construct higher‐order transmit antenna systems. Using interleaved‐MRD codes further reduces the complexity (compared with normal MRD codes) of the decoding algorithm. Fourthly, the use of Gaussian integers is utilized in mapping MRD‐based STBCs to complex constellations. Furthermore, it is described how an efficient and computationally less complex Gabidulin's decoding algorithm can be exploited for decoding complex MRD‐STBCs. The decoding results have been compared against hard‐decision maximum likelihood decoding. Under this decoding scheme, MRD‐STBCs have been shown to be potential candidate for higher transmit antenna systems as the decoding complexity of Gabidulin's algorithm is far less, and its performance for decoding MRD‐STBCs is somewhat reasonable. Copyright © 2015 John Wiley & Sons, Ltd.
Can environmental constraints determine random patterns of plant species co‐occurrence?
Authors: García‐Baquero Gonzalo , Crujeiras Rosa M.
Published: February 2015

Plant community ecologists use the null model approach to infer assembly processes from observed patterns of species co‐occurrence. In about a third of published studies, the null hypothesis of random assembly cannot be rejected. When this occurs, plant ecologists interpret that the observed random pattern is not environmentally constrained – but probably generated by stochastic processes. The null model approach (using theC‐score and the discrepancy index) was used to test for random assembly under two simulation algorithms. Logistic regression, distance‐based redundancy analysis, and constrained ordination were used to test for environmental determinism (species segregation along environmental gradients or turnover and species aggregation). This article introduces an environmentally determined community of alpine hydrophytes that presents itself as randomly assembled. The pathway through which the random pattern arises in this community is suggested to be as follows: Two simultaneous environmental processes, one leading to species aggregation and the other leading to species segregation, concurrently generate the observed pattern, which results to be neither aggregated nor segregated – butrandom. A simulation study supports this suggestion. Although apparently simple, the null model approach seems to assume that a single ecological factor prevails or that if several factors decisively influence the community, then they all exert their influence in the same direction, generating either aggregation or segregation. As these assumptions are unlikely to hold in most cases and assembly processes cannot be inferred from random patterns, we would like to propose plant ecologists to investigate specifically the ecological processes responsible for observed random patterns, instead of trying to infer processes from patterns.
Uncertainties in the projection of species distributions related to general circulation models
Authors: Goberville Eric , Beaugrand Grégory , Hautekèete Nina‐Coralie , Piquot Yves , Luczak Christophe
Published: February 2015

Ecological Niche Models (ENMs) are increasingly used by ecologists to project species potential future distribution. However, the application of such models may be challenging, and some caveats have already been identified. While studies have generally shown that projections may be sensitive to theENMapplied or the emission scenario, to name just a few, the sensitivity ofENM‐based scenarios to General Circulation Models (GCMs) has been often underappreciated. Here, using a multi‐GCMand multi‐emission scenario approach, we evaluated the variability in projected distributions under future climate conditions. We modeled the ecological realized niche (sensuHutchinson) and predicted the baseline distribution of species with contrasting spatial patterns and representative of two major functional groups of European trees: the dwarf birch and the sweet chestnut. Their future distributions were then projected onto future climatic conditions derived from sevenGCMs and four emissions scenarios using the new Representative Concentration Pathways (RCPs) developed for the Intergovernmental Panel on Climate Change (IPCC)AR5 report. Uncertainties arising fromGCMs and those resulting from emissions scenarios were quantified and compared. Our study reveals that scenarios of future species distribution exhibit broad differences, depending not only on emissions scenarios but also onGCMs. We found that the between‐GCMvariability was greater than the between‐RCPvariability for the next decades and both types of variability reached a similar level at the end of this century. Our result highlights that a combined multi‐GCMand multi‐RCPapproach is needed to better consider potential trajectories and uncertainties in future species distributions. In all cases, between‐GCMvariability increases with the level of warming, and if nothing is done to alleviate global warming, future species spatial distribution may become more and more difficult to anticipate. When future species spatial distributions are examined, we propose to use a large number ofGCMs andRCPs to better anticipate potential trajectories and quantify uncertainties.
Oxidative myocardial damage in human cocaine‐related cardiomyopathy
Authors: Frustaci Andrea , Russo Matteo A. , Morgante Emanuela , Scopelliti Fernanda , Aquilano Katia , Ciriolo Maria R. , Grande Claudia , Verardo Romina , Chimenti Cristina
Published: February 2015

Aims

The pathogenesis of cocaine‐related cardiomyopathy (CCM) is still unclear. Oxidative damage from cocaine‐generated reactive oxygen species (ROS) overcoming myocardial antioxidant reserve has been hypothesized by experimental studies.

Methods and results

Ten (2.3%) of 430 consecutive cases with dilated cardiomyopathy (DCM) were attributed to CCM. Endomyocardial biopsies from CCM were retrospectively investigated with histology, electron microscopy, immunohistochemistry (graded 0–3), and Western blot analysis for inducible nitric oxide synthase (iNOS) and nitrotyrosine. Oxidative damage to DNA was investigated by immunostaining for 8‐hydroxydeoxyguanosine (8‐OHdG), while apoptosis and necrosis were evaluated by in situ ligation with hairpin probes. Myocardial anti‐oxidant reserve was evaluated through assessment of superoxide dismutase (SOD1‐2) and catalase (CT) activity in two frozen samples from each patient. Results were compared with idiopathic DCM and normal controls. Cardiomyocytes were bigger and myocardial fibrosis was more pronounced in CCM than in the DCM cohort. Contraction band necrosis was always detectable only in CCM with sparse lymphocytic infiltrates in three cases. Both iNOS and nitrotyrosine were significantly more expressed in CCM than in DCM. Immunostaining for 8‐OHdG, cardiomyocyte apoptosis, and necrosis were significantly increased in CCM compared with controls and DCM. Myocardial SOD1 and CT activity was significantly decreased compared with DCM and controls, and correlated with cell death and severity of left ventricular dysfunction.

Conclusion

Oxidative stress is a major mechanism of myocardial damage in human CCM. It concurs with calcium overload to myocyte dysfunction and death.
IL‐17‐producing CD4+ T cells contribute to the loss of B‐cell tolerance in experimental autoimmune myasthenia gravis
Authors: Schaffert Hanne , Pelz Andreas , Saxena Abhishek , Losen Mario , Meisel Andreas , Thiel Andreas , Kohler Siegfried
Published: February 2015

The role of Th17 cells in the pathogenesis of autoantibody‐mediated diseases is unclear. Here, we assessed the contribution of Th17 cells to the pathogenesis of experimental autoimmune myasthenia gravis (EAMG), which is induced by repetitive immunizations with Torpedo californica acetylcholine receptor (tAChR). We show that a significant fraction of tAChR‐specific CD4+ T cells is producing IL‐17. IL‐17ko mice developed fewer or no EAMG symptoms, although the frequencies of tAChR‐specific CD4+ T cells secreting IL‐2, IFN‐γ, or IL‐21, and the percentage of FoxP3+ Treg cells were similar to WT mice. Even though the total anti‐tAChR antibody levels were equal, the complement fixating IgG2b subtype was reduced in IL‐17ko as compared to WT mice. Most importantly, pathogenic anti‐murine AChR antibodies were significantly lower in IL‐17ko mice. Furthermore, we confirmed the role of Th17 cells in EAMG pathogenesis by the reconstitution of TCR β/δko mice with WT or IL‐17ko CD4+ T cells. In conclusion, we show that the level of IgG2b and the loss of B‐cell tolerance, which results in pathogenic anti‐murine AChR‐specific antibodies, are dependent on IL‐17 production by CD4+ T cells. Thus, we describe here for the first time how Th17 cells are involved in the induction of classical antibody‐mediated autoimmunity.
Protective dendritic cell responses against listeriosis induced by the short form of the deubiquitinating enzyme CYLD are inhibited by full‐length CYLD
Authors: Wurm Rebecca , Just Sissy , Wang Xu , Wex Katharina , Schmid Ursula , Blanchard Nicolas , Waisman Ari , Schild Hans‐Jörg , Deckert Martina , Naumann Michael , Schlüter Dirk , Nishanth Gopala
Published: February 2015

The deubiquitinating enzyme CYLD is an important tumor suppressor and inhibitor of immune responses. In contrast to full‐length CYLD, the immunological function of the naturally occurring short splice variant of CYLD (sCYLD) is insufficiently described. Previously, we showed that DCs, which lack full‐length CYLD but express sCYLD, exhibit augmented NF‐κB and DC activation. To explore the function of sCYLD in infection, we investigated whether DC‐specific sCYLD regulates the pathogenesis of listeriosis. Upon Listeria monocytogenes infection of CD11c‐Cre Cyldex7/8 fl/fl mice, infection of CD8α+ DCs, which are crucial for the establishment of listeriosis in the spleen, was not affected. However, NF‐κB activity of CD11c‐Cre Cyldex7/8 fl/fl DCs was increased, while activation of ERK and p38 was normal. In addition, CD11c‐Cre Cyldex7/8 fl/fl DCs produced more TNF, IL‐10, and IL‐12 upon infection, which led to enhanced stimulation of IFN‐γ‐producing NK cells. In addition CD11c‐Cre Cyldex7/8 fl/fl DCs presented Listeria Ag more efficiently to CD8+ T cells resulting in a stronger pathogen‐specific CD8+ T‐cell proliferation and more IFN‐γ production. Collectively, the improved innate and adaptive immunity and survival during listeriosis identify the DC‐specific FL‐CYLD/sCYLD balance as a potential target to modulate NK‐cell and Ag‐specific CD8+ T‐cell responses.
New parameters for evaluating the quality of commercial krill oil capsules from the aspect of lipid oxidation and non‐enzymatic browning reactions
Authors: Lu Fung Sieng Henna , Bruheim Inge , Jacobsen Charlotte
Published: February 2015

Classical techniques such as Peroxide Value and Anisidine Value are not useful to evaluate the quality of krill oil. These techniques may underestimate lipid oxidation and other degradative reactions in krill oil. Therefore, the main objective of this study was to evaluate the quality of eight different commercial krill oil capsules through parameters such as: investigation of chemical compositions (bioactive compounds such as phospholipids, n‐3 polyunsaturated fatty acids, antioxidants), hydrophobic pyrroles, and volatile profiles (lipid and Strecker‐derived volatiles, pyridines, pyrazines, and their alkyl derivatives, sulphur and amino compounds). The data of chemical composition of krill oil were correlated well with those from volatile measurement. Through investigating volatile profile, new insights into the lipid oxidation and non‐enzymatic browning reactions in krill oil were obtained, and the quality among different commercial krill oil products was differentiated.

Practical applications: Different from fish oil, krill oil has a much more complex matrix. Therefore, classical techniques, which are useful to differentiate the quality of fish oil are not applicable to krill oil. This work provides new parameters to differentiate the quality of krill oil through the measurement of bioactive compounds and hydrophobic pyrroles in krill oil, and investigation of volatile profiles of krill oil from the aspect of lipid oxidation and non‐enzymatic browning reactions.

The quality of commercial krill oil capsules could be differentiated through parameters such as chemical compositions (bioactive compounds), hydrophobic pyrroles, and volatile profiles (volatiles derived from lipid oxidation and non‐enzymatic browning reactions). The data of chemical composition of krill oil were correlated well with those from volatile measurement and new insights into lipid oxidation and non‐enzymatic browning reactions in krill oil were obtained.
Homogeneous and Semi‐Heterogeneous Magnetically Retrievable Bis‐N‐Heterocyclic Carbene Rhodium(I) Based Catalysts for Selective Hydroaminomethylation Reactions
Authors: Dutta Bishnu , Schwarz Rony , Omar Suheir , Natour Suzana , Abu‐Reziq Raed
Published: February 2015

The preparation of various bis‐N‐heterocyclic carbene (bis‐NHC) complexes of rhodium and their application in the hydroaminomethylation of vinyl arenes was investigated. Various reaction parameters such as solvent, temperature, and pressure were tested, and the optimized protocol was applied to a wide variety of vinyl arenes and amines to afford the corresponding amines in good yields with high selectivity towards the branched product. The bis‐NHC‐based catalyst demonstrated superior reactivity and selectivity compared to catalysts containing bidentate phosphine or monodentate NHC ligands. A triethoxysilyl‐functionalized bis‐NHC ligand was immobilized on magnetic nanoparticles and then utilized to bind a rhodium catalyst. The resulting catalytic system was successfully employed in hydroaminomethylation reactions. The catalyst exhibited excellent reactivity, high selectivity, and was simply recovered from the reaction medium by applying an external magnetic field.
One‐Pot Enantioselective Synthesis of 1,4‐Naphthoquinone‐Derived Polycycles through Oxidative Dearomatization and Aminocatalysis
Authors: Pantaine Loïc , Coeffard Vincent , Moreau Xavier , Greck Christine
Published: February 2015

A synthetic process merging oxidative dearomatization and asymmetric aminocatalysis in a single vessel is reported. The PhI(OAc)2‐mediated oxidation of 1,4‐dihydroxynaphthalene is followed by a trienamine‐mediated Diels–Alder cycloaddition/aldol reaction or a trienamine‐mediated Diels–Alder cycloaddition/oxidation sequence depending on the dienal substitution pattern. The polycyclic compounds are obtained in good yields with enantiomeric excesses up to 99 %. Additionally, these polycyclic architectures can be synthesized with similar enantioselectivities through an unprecedented one‐pot marriage of bodipy‐photocatalyzed oxidative dearomatization of 1‐naphthol and asymmetric aminocatalysis. A catalytic cycle is suggested to explain the reaction outcome.
Asymmetric Organocatalytic Synthesis of Highly Substituted Cyclohexenols by Domino Double‐Michael Reactions of 1‐Hydroxy‐1,4‐dien‐3‐ones and 2‐Alkylidenemalononitriles
Authors: Jang Yeong‐Jiunn , Chen Yu‐Shan , Lee Chia‐Jui , Chen Chi‐Han , Reddy Ganapuram Madhusudhan , Ko Chi‐Ting , Lin Wenwei
Published: February 2015

A facile asymmetric synthetic protocol to afford 2,6‐disubstituted 4‐hydroxy‐3‐oxocyclohex‐3‐ene‐1,1‐dicarbonitriles has been developed through the domino double‐Michael addition of 1,5‐disubstituted 1‐hydroxy‐1,4‐dien‐3‐ones to 2‐alkylidenemalononitriles using quinine as the catalyst. This simple organocatalytic domino process provides access to various highly functionalized chiral 4‐hydroxy‐3‐oxocyclohex‐3‐enes, which are the rarely reported chiral diketo cyclohexane analogues, in moderate‐to‐good yields and enantioselectivities and with excellent diastereoselectivities (>25:1 dr).
Can we really reduce ethnic prejudice outside the lab? A meta‐analysis of direct and indirect contact interventions
Authors: Lemmer Gunnar , Wagner Ulrich
Published: February 2015

The present meta‐analysis tested the effectiveness of contact‐based interventions for the reduction of ethnic prejudice. Up to now, a meta‐analysis summarizing the results of real‐world interventions that rest on the intergroup contact theory has been missing. We included evaluations of programs realizing direct (i.e., face‐to‐face) and/or indirect (i.e., extended or virtual) contact in real‐world settings outside the lab. The interventions' effectiveness was tested shortly after their end (k = 123 comparisons, N = 11 371 participants) and with a delay of at least 1 month (k = 25, N = 1650). Our data show that contact interventions improve ethnic attitudes. Importantly, changes persist over time. Furthermore, not only direct but also indirect contact interventions are successful. In addition, contact programs are effective even in the context of a serious societal conflict (e.g., in the Middle East). Although changes are typically larger for ethnic majorities, there is an impact on minorities, too. Finally, contact interventions not only improve attitudes toward individuals involved in the program, their effects also generalize to outgroups as a whole. In sum, social psychology provides an intervention for prejudice reduction that can be successfully implemented in the practical field. Copyright © 2015 John Wiley & Sons, Ltd.
In the name of democracy: The value of democracy explains leniency towards wrongdoings as a function of group political organization
Authors: Pereira Andrea , Falomir‐Pichastor Juan Manuel , Berent Jacques , Staerklé Christian , Butera Fabrizio
Published: February 2015

According to the “democracy‐as‐value” hypothesis, democracy has become an ideological belief system providing social value to democratic individuals, groups and institutions, granting legitimacy to their actions (even if dishonest or violent), and protecting them from consecutive punishments. The present research investigates the extent to which this legitimizing process is based on the individual endorsement of democratic principles. Across four experiments, following the misdeed of a (few) group member(s), respondents who valued democratic group organization and democracy in general expressed more lenient retributive justice judgments towards democratic (as compared with nondemocratic) offender groups. These findings shed light on the ways in which democratic ideology infuses justice judgments. Copyright © 2015 John Wiley & Sons, Ltd.
Electrochemical Properties of a Gold Nanoseed Particle‐Attached Nickel Electrode
Authors: Uemoto Takahiro , Nakayama Yosuke , Chen Xiaomei , Chang Gang , Oyama Munetaka
Published: February 2015

Gold nanoseed particles (AuNSPs) of ca. 3.5 nm were attached on a Ni disk electrode, and the electrochemical properties of the thus‐prepared AuNSP‐attached nickel (AuNSP/Ni) electrode were investigated. As a remarkable effect of AuNSPs, cyclic voltammograms of Fe(CN)${{{4- \hfill \atop 6\hfill}}}$ recorded with an AuNSP/Ni electrode was reversible and almost identical to those recorded with an Au disk electrode, while a reversible response was not observed with a Ni disk electrode. The similar tendency was observed for the electrochemical oxidation of uric acid and glucose. Also, AuNSPs was proved to suppress the redox reactions of the Ni electrode in alkaline solutions.
Electrochemical Properties of Polypyrrole Doped by Alternating Polymer Micelles
Authors: Gryczan Piotr , Kisiel Anna , Michalska Agata , Maksymiuk Krzysztof
Published: February 2015

Micelles composed of alternating polymer – poly(maleic anhydride alt‐1‐octadecene) (crosslinked and hydrolyzed) of diameter close to 200 nm were incorporated to polypyrrole films in course of potentiostatic polymerization. In this way a novel composite material was obtained with quite unique properties compared to typical polypyrrole. In the present case micelles possessing negatively charged carboxyl groups served as counter ions. The presence of micelles determines nontypical properties of the films such as separate potential ranges corresponding either to cation‐ and anion‐exchange or to low concentration of mobile ions. Factors affecting sensitivity to ions of different charges are discussed. Due to presence of carboxyl groups in the micelles, the obtained films exhibit pH sensitivity, both in potentiometric and voltammetric measurements mode.
Potentiometric Solid‐Contact Multisensor System for Simultaneous Measurement of Several Ions
Authors: Jasiński Artur , Urbanowicz Marcin , Guziński Marcin , Bocheńska Maria
Published: February 2015

The design and performance of potentiometric multisensor system made in solid‐contact technology is described. Both, the measuring electrodes as well as the reference electrode are in a compact cell. The system allows for simultaneous measurement of various ions. The characteristics of the electrodes for Na+, K+ and Ca2+ ions were determined using the designed system and compared with ISEs of the same membrane composition in classical system. The potentiometric cells were used to determine the concentration of the ions in synthetic and real human sweat samples. The obtained results for synthetic samples were compared to the expected values and for collected real sample of sweat were compared to the results obtained by flame photometry (Na+, K+) and by AAS (Ca2+).
Photoelectrochemical Water Splitting. A Status Assessment
Authors: Peter Laurence M.
Published: February 2015

The basic concepts of light‐driven water splitting using semiconductor‐based photoelectrochemical devices are reviewed with the emphasis on the prospects of achieving solar to hydrogen (STH) efficiencies that will enable the development of competitive hydrogen generation technologies to begin to replace those based on fossil fuels. Examples of the calculation of conversion efficiencies are given for different approaches to solar photoelectrolysis, illustrating the need to use well‐defined figures of merit in all publications dealing with the photoelectrochemical generation of solar fuels.
Planar Impedancemetric NO Sensor with Thick Film Perovskite Electrodes Based on Samarium Cobaltite
Authors: Cvejin Katarina , Manjakkal Libu , Kulawik Jan , Zaraska Krzysztof , Szwagierczak Dorota
Published: February 2015

Impedancemetric NO sensors were fabricated, comprising yttria stabilized zirconia disc with thick film Sm0.9Sr0.1CoO3−δ electrodes of different design. Impedance measurements were performed at 600–800 °C for frequencies 0.01 Hz–100 kHz, in gas mixtures with 0–400 ppm of NO. The smaller arc on Nyquist plots can be associated with solid electrolyte‐electrode interfacial phenomena, while the bigger one to the perovskite electrode reactions. As NO concentration increases, the bigger arc decreases and its maximum shifts toward higher frequencies. Both the sensitivity and the applicable NO concentration range were found to be dependent on the sensor design, temperature and chosen frequency.
Carbon Microsphere – Polystyrene Composite Electrode for Three‐Phase Boundary Oil Analysis: Quinizarin in Methyllaurate
Authors: Ahn Sunyhik D. , Kaluza Dawid , Jönsson‐Niedziólka Martin , Mitchels John M. , Marken Frank
Published: February 2015

Oil analysis for the case of quinizarin in methyllaurate is demonstrated with a disposable carbon microsphere – polystyrene composite electrode. Oxidation and reduction of quinizarin are observed as three‐phase boundary processes at the immiscible oil | water | carbon interface. Randomly packed glassy carbon microspheres (2–12 µm diameter) held together with a polystyrene binder (ca. 0.1 % by weight) are immobilized onto a pencil lead electrode and used for electrochemical oil analysis. Pore‐filling with oil is optimised for voltammetric detection and fluorescence spectroscopy is employed to support the mechanistic analysis based on voltammetry. Future applications for a wider range of oils and additives are proposed.
Potentiodynamic Electrochemical Impedance Spectroscopy for Underpotential Deposition Processes
Authors: Ragoisha G. A.
Published: February 2015

Potentiodynamic electrochemical impedance spectroscopy makes available, from cyclic potential scan combined with frequency response acquisition, a set of potentiodynamic profiles of characteristic electrochemical variables in addition to a voltammetric profile. Especially informative in the underpotential deposition is the double layer capacitance profile which characterises alterations of the interface status during the potential scan. Potentiodynamic profiles of charge transfer resistance and Warburg coefficient present complementary information about faradaic part of the electrochemical response. Profiles of adsorption capacitance are available in the reversible UPD.
Investigations into the Speciation of Inorganic Arsenic in Weakly Alkaline Medium by Voltammetry
Authors: Zakharova Elza A. , Noskova Galina N. , Moskaleva Marina L. , Elesova Elena E. , Wildgoose Gregory G.
Published: February 2015

The speciation of inorganic forms of arsenic was studied using anodic stripping voltammetry (ASV) at a gold microelectrode in conjunction with photoreduction of As(V). Sodium sulfite (0.1 M) and ammonium buffer (pH≥9.5) were selected as both background electrolyte and photo‐reductive reagent. Oxygen was removed by radical chain reactions with sulfite. The proposed speciation method was validated for mixtures of arsenic As(III/V) at concentrations up to 1 mg L−1. The calculatedLODof As(III/V) was 0.06 µg L−1(3σ,tdep40 s). Any interference from nitrate anions present at up to millimolar concentration was minimized by their photoreduction.
Managing Internal Corrosion of Mild Steel Pipelines in CO2‐Enhanced Oil Recovery Multiphase Flow Conditions
Authors: Wang Zi Ming , Liu Xiao Tian , Han Xia , Zhang Jian
Published: February 2015

The “carbon capture, utilization and storage” project has attracted considerable attention in recent years as the demands for reducing CO2 emissions increased. However, the produced fluids during CO2‐enhanced oil recovery (EOR) production are supersaturated with high‐pressure CO2 gas, which leads to serious corrosion damages of the pipelines. To model the corrosive conditions during CO2–EOR production, a self‐designed multiphase flow loop for internal corrosion evaluation was built. The role of flow patterns and emulsification that decisively influencing pipeline corrosion was systematically investigated. It was found that a higher gas‐to‐liquid ratio could be beneficial for reducing pipeline corrosion, which was attributed to a reduction in slug frequency and an enhancement in the stirring effect on the oil–brine mixtures. It was also found that corrosion can be completely inhibited if the transporting liquids were properly controlled under water‐in‐oil emulsion condition. A model considering the transport parameters that ensures the safety of crude‐oil transportation is proposed. It suggests that corrosion control by designing the transport parameters would be a suitable and economic method for tackling the corrosion damages to CO2–EOR pipelines. These ideas have been accepted for guiding the pipeline engineering in the CO2–EOR section of the Shengli oilfield.
Improved discrimination of subglacial and periglacial erosion using 10Be concentration measurements in subglacial and supraglacial sediment load of the Bossons glacier (Mont Blanc massif, France)
Authors: Guillon Hervé , Mugnier Jean‐Louis , Buoncristiani Jean‐François , Carcaillet Julien , Godon Cécile , Prud'homme Charlotte , van der Beek Peter , Vassallo Riccardo
Published: February 2015

Deciphering the complex interplays between climate, uplift and erosion is not straightforward and estimating present‐day erosion rates can provide useful insights. Glaciers are thought to be powerful erosional agents, but most published ‘glacial’ erosion rates combine periglacial, subglacial and proglacial erosion processes. Within a glaciated catchment, sediments found in subglacial streams originate either from glacial erosion of substratum or from the rock walls above the glacier that contribute to the supraglacial load. Terrestrial cosmogenic nuclides (TCN) are produced by interactions between cosmic ray particles and element targets at the surface of the Earth, but their concentration becomes negligible under 15 m of ice. Measuring TCN concentrations in quartz sand sampled in subglacial streams and in supraglacial channels is statistically compliant with stochastic processes (e.g. rockfalls) and may be used to discriminate subglacial and periglacial erosion. Results for two subglacial streams of the Bossons glacier (Mont Blanc massif, France) show that the proportion of sediments originating from glacially eroded bedrock is not constant: it varies from 50% to 90% (n = 6). The difference between the two streams is probably linked to the presence or absence of supraglacial channels and sinkholes, which are common features of alpine glaciers. Therefore, most of the published mean catchment glacial erosion rates should not be directly interpreted as subglacial erosion rates. In the case of catchments with efficient periglacial erosion and particularly rockfalls, the proportion of sediments in the subglacial stream originating from the supraglacial load could be considerable and the subglacial erosion rate overestimated. Here, we estimate warm‐based subglacial and periglacial erosion rates to be of the same order of magnitude: 0.39 ± 0.33 and 0.29 ± 0.17 mm a−1, respectively. Copyright © 2015 John Wiley & Sons, Ltd.
Coupling patterns between para‐glacial and permafrost degradation responses in Antarctica
Authors: Oliva Marc , Ruiz‐Fernández Jesús
Published: February 2015

The recently deglaciated environments in maritime permafrost regions are usually affected by very active paraglacial processes. Elephant Point is an ice‐free area of 1.16 km2 located in the SW of Livingston island (South Shetland Islands, Antarctica). Between 1956–2010 the retreat of the ice cap covering most part of this island has exposed 17.3% of the land surface in this peninsula. Two geomorphological units were identified in this new ice‐free area: a moraine extending from the western to the eastern coastlines and a relatively flat proglacial surface. The glacier in 1956 sat in contact with the northern slope of the moraine, but its accelerated retreat ‐ in parallel to the warming trend recorded in the Antarctic Peninsula ‐ left these areas free of glacier ice. Subsequently, the postglacial evolution was controlled by the relaxation phase typical of paraglacial systems. The typology and intensity of geomorphological processes show a significantly different dynamics between the southern and northern slopes of the moraine. This pattern is related to the different stage of paraglacial adjustment in both slopes. In the southern side, on coarser sediments, pronival ramparts, debris flows and alluvial fans are distributed, with a low to moderate activity of slope processes. In the northern side, mass wasting processes are extremely active on fine‐grained unconsolidated sediments. Ice‐rich permafrost is being degraded by thermokarst processes. Landslides and mudflows transfer large amounts of sediments down‐slope. The surface affected by retrogressive‐thaw slumps in the moraine has been quantified in 24,172 m2, which accounts for 9.6% of its surface. The abundance of kettle‐lakes is also indicative of the degradation of the ground ice. Paraglacial processes are expected to continue in the moraine and proglacial area in the near future, although their intensity and duration will depend on the magnitude and rate of future climate trends in the northern Antarctic Peninsula. Copyright © 2015 John Wiley & Sons, Ltd.
Modelling suspended sediment concentration and load in a transport‐limited alluvial gully in northern Queensland, Australia
Authors: Rose Calvin W. , Shellberg Jeffrey G. , Brooks Andrew P.
Published: February 2015

Alluvial gullies are often formed in dispersible sodic soils along steep banks of incised river channels. Field data collected by Shellberg et al. (Earth Surface Processes and Landforms 38: 1765–1778, 2013) from a gully outlet in northern Australia showed little hysteresis between water discharge and fine (<63 µm) and coarse (>63 µm) suspended sediment, indicating transport‐limited rather than source‐limited conditions. The major source of the fine (silt/clay) component was the sodic soils of upstream gully scarps, and the coarser (sand) component was sourced locally from channel bed material. In this companion paper at the same study site, a new method was developed for combining the settling velocity characteristics of these two sediment source components to estimate the average settling velocity of the total suspended sediment. This was compared to the analysis of limited sediment samples collected during flood conditions. These settling velocity data were used in the steady‐state transport limit theory of Hairsine and Rose (Water Resources Research 28: 237–243, 245–250, 1992) that successfully predicted field data of concentrations and loads at a cross‐section, regardless of the complexity of transport‐limited upstream sources (sheet erosion, scalds, rills, gullies, mass failure, bank and bed erosion, other disturbed areas). The analysis required calibration of a key model parameter, the fraction of total stream power (F ≈ 0.025) that is effective in re‐entraining sediment. Practical recommendations are provided for the prediction of sediment loads from other alluvial gullies in the region with similar hydrogeomorphic conditions, using average stream power efficiency factors for suspended silt/clay (Fw ≈ 0.016) and sand (Fs ≈ 0.038) respectively, but with no requirement for field data on sediment concentrations. Only basic field data on settling velocity characteristics from soil samples, channel geometry measurements, estimates of water velocity and discharge, and associated error margins are needed for transport limit theory predictions of concentration and load. This theory is simpler than that required in source‐limited situations. Copyright © 2015 John Wiley & Sons, Ltd.
Retracted: Using bald eagles to track spatial (1999–2008) and temporal (1987–1992, 1999–2003, and 2004–2008) trends of contaminants in Michigan's aquatic ecosystems
Authors: Wierda Michael R. , Leith Katherine F. , Grubb Teryl G. , Sikarskie James G. , Best David A. , Bowerman William
Published: February 2015

Retraction: ‘Using bald eagles to track spatial (1999–2008) and temporal (1987–1992, 1999–2003, and 2004–2008) trends of contaminants in Michigan's aquatic ecosystems’ by Michael R. Wierda, Katherine F. Leith, Teryl G. Grubb, James G. Sikarskie, David A. Best, and William Bowerman

The above article from Environmental Toxicology and Chemistry, published online on 10 February 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor in Chief, G.A. Burton, Jr., SETAC and Wiley Periodicals, Inc. The retraction has been agreed since the authors determined that some of the plasma samples run at Clemson University had failed quality assurance/quality control and were retested. The concentrations have since been corrected and validated.

Reference

Wierda MR, Leith KF, Grubb TG, Sikarskie JG, Best DA, Bowerman W. 2015. Using bald eagles to track spatial (1999–2008) and temporal (1987–1992, 1999–2003, and 2004–2008) trends of contaminants in Michigan's aquatic ecosystems. Environ ToxicolChem doi:10.1002/etc.2859.
Circumpolar contamination in eggs of the high-Arctic ivory gull Pagophila eburnea
Authors: Lucia Magali , Verboven Nanette , Strøm Hallvard , Miljeteig Cecilie , Gavrilo Maria V. , Braune Birgit M. , Boertmann David , Gabrielsen Geir W.
Published: February 2015

The ivory gull Pagophila eburnea is a high-Arctic species threatened by climate change and contaminants. The objective of the present study was to assess spatial variation of contaminant levels (organochlorines [OCs], brominated flame retardants [BFRs], perfluorinated alkyl substances [PFASs], and mercury [Hg]) in ivory gulls breeding in different areas across the Arctic region as a baseline for potential future changes associated with climate change. Contaminants were already determined in eggs from Canada (Seymour Island; except PFASs), Svalbard in Norway (Svenskøya), and 3 sites in Russia (Nagurskoe, Cape Klyuv, and Domashny). New data from Greenland allowed the investigation of a possible longitudinal gradient of contamination. The most quantitatively abundant OCs were p,p′-dichlorodiphenyldichloroethylene (DDE) and polychlorobiphenyls. Mercury concentrations were higher in Canada compared with other colonies. Eggs from Nagurskoe often were characterized by higher OC and BFR concentrations. Concentrations gradually decreased in colonies situated east of Nagurskoe. In contrast, PFAS concentrations, especially perfluorooctanoate and perfluorononanoate, were higher in Greenland. Some of the contaminants, especially Hg and p,p′-DDE, exceeded published thresholds known to disrupt the reproductive success of avian species. Overall, the levels of OCs, BFRs, and PFASs did not suggest direct lethal exposure to these compounds, but their potential synergetic/additive sublethal effects warrant monitoring. Environ Toxicol Chem 2015;34:1552–1561. © 2015 SETAC
Improving Forecast of Binary Rare Events Data: A GAM‐Based Approach
Authors: Calabrese Raffaella , Osmetti Silvia Angela
Published: February 2015

This paper develops a method for modelling binary response data in a regression model with highly unbalanced class sizes. When the class sizes are highly unbalanced and the minority class represents a rare event, conventional regression analysis, i.e. logistic regression models, could underestimate the probability of the rare event. To overcome this drawback, we introduce a flexible skewed link function based on the quantile function of the generalized extreme value (GEV) distribution in a generalized additive model (GAM). The proposed model is known as generalized extreme value additive (GEVA) regression model, and a modified version of the local scoring algorithm is suggested to estimate it. We apply the proposed model to a dataset on Italian small and medium enterprises (SMEs) to estimate the default probability of SMEs. Our proposal performs better than the logistic (linear or additive) model in terms of predictive accuracy. Copyright © 2015 John Wiley & Sons, Ltd.
Experimental Investigation into a Novel Modular PEMFC Fuel Cell Stack
Authors: Scott P. , Chen Y. , Calay R. , Bhinder F.
Published: February 2015

The polymer electrolyte membrane fuel cell (PEMFC), despite being regarded as an ideal replacement to the internal combustion engine, is still not an economically attractive prime‐mover due to a number of key challenges that have yet to be fully resolved; such as degradation to cell components resulting in inadequate lifetimes, specialized manufacturing processes, and poor gravimetric/volumetric energy densities. This paper presents a stack concept which replaces the conventional bipolar plate (BPP), a component that is responsible for a large proportion of stack cost and volume in traditional fuel cell stack designs. The stack architecture compromises of active and passive components which are suited to mass manufacture and maintain functionality that the BPP fulfilled. Furthermore, the design allows the implementation of a fault tolerant system (FTS) which can bypass faulty cells while still ensuring electrical output. The stack architecture is presented and characterized over a number of operating scenarios. The experimental studies suggest that the performance of the new design is similar to that of traditional stacks over a number of operating conditions despite the removal of the BPP and the FTS continued to operate at a desired operating criterion despite the loss of a cell within the stack
Preparation of NiCo2O4 Nanosheet Arrays and its High Catalytic Performance for H2O2 Electroreduction
Authors: Wang Y. , Cheng K. , Cao D. , Yang F. , Yan P. , Zhang W. , Wang G.
Published: February 2015

Ni foam supporting‐NiCo2O4 nanosheet arrays (NiCo2O4/Ni foam) are successfully prepared by electrodeposition of the hydroxide precursor, followed by a thermal treatment in air without any template and surfactant. The morphology of NiCo2O4 nanosheet arrays is characterized by scanning electron microscope and transmission electron microscopy. The structure is analyzed using X‐ray diffractometer, X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The catalytic performance of NiCo2O4/Ni foam electrode for H2O2 electroreduction in KOH solution is evaluated by means of cycle voltammetry and chronoamperometry, which exhibits an excellent catalytic performance and superior stability for H2O2 electroreduction. The reduction current density of H2O2 on NiCo2O4/Ni foam electrode is 0.378 A cm−2 at –0.4 V in the solution containing 3.0 mol L−1 KOH + 0.4 mol L−1 H2O2, which is much larger than that on other metal oxides reported previously.
Advantages of a Polyimide Membrane Support in Nonhumidified Fluorohydrogenate‐Polymer Composite Membrane Fuel Cells
Authors: Kiatkittikul P. , Nohira T. , Hagiwara R.
Published: February 2015

We have successfully prepared composite membranes consisting of the ionic liquid N‐ethyl‐N‐methylpyrrolidinium fluorohydrogenate and the polymer 2‐hydroxyethylmethacrylate and have secured them on a polyimide (PI) membrane support. The resulting EMPyr(FH)1.7F–HEMA (9:1 molar ratio) composite possesses ionic conductivity of 75 mS cm−1 at 120 °C when a 16‐µm support is employed, showing improved performance with elevated temperature; this marks a significant difference from devices using conventional polytetrafluoroethylene supports. In the single cell test, a maximum power density of 31 mW cm−2 is observed at 120 °C. Cross‐sectional SEM images of the corresponding membrane electrode assemblies reveal no significant difference in membrane thickness before and after cell testing, implying that this support does not suffer from membrane softening issues.