bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication and Photocatalytic Properties of TiO2/Reduced Graphene Oxide/Ag Nanocomposites with UV/Vis Response
Authors: Gou Xueli , Cheng Yongliang , Liu Bin , Yang Bingjun , Yan Xingbin 
Published: April 2015

AbstractNovel one‐dimensional TiO2 nanofibers/reduced graphene oxide/Ag nanoparticles (TiO2/rGO/Ag) nanocomposite photocatalysts with UV/Vis response properties were fabricated by wrapping rGO sheets around TiO2 nanofibers and then loading Ag nanoparticles onto the surfaces of TiO2/rGO. The prepared samples were characterized by scanning electron microscopy, high‐resolution transmission electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectroscopy, and UV/Vis diffuse reflectance spectroscopy. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of an aqueous solution of rhodamine B (RhB) under UV/Vis light irradiation. The results showed that the introduction of rGO and Ag greatly improved the photocatalytic activity of the TiO2 nanofibers, and this enhancement was attributed to the hybridization of rGO possessing specific electronic effects and Ag nanoparticles showing surface plasmon resonance effects. As a consequence, extension of the absorption spectrum to the visible region and efficient restriction of the recombination of photogenerated carriers were achieved.
Controlling the Activities of the Diiron Centre in Bacterial Monooxygenases: Lessons from Mutagenesis and Biodiversity
Authors: Nichol Tim , Murrell J. Colin , Smith Thomas J. 
Published: April 2015

AbstractThe soluble diiron monooxygenases (SDIMOs) are a diverse group of bacterial enzymes that possess a deeply buried binuclear iron centre that forms an oxo‐diferryl (FeIV) intermediate that is capable of oxygenating a wide range of unfunctionalised hydrocarbons and other hydrophobic organic molecules, ranging in size from methane to diaromatics such as naphthalene and substituted biphenyls. In the environment, these enzymes are important in bioremediation of hydrocarbons and chlorinated hydrocarbons and in mitigation of the greenhouse effect due to methane, and also have numerous potential applications in synthetic organic chemistry. In this review we consider how both natural variations among the enzymes and an increasing body of evidence from mutagenesis studies cast light on how the protein controls the size of substrates that can access the active site, the precision of regio‐ and stereoselectivity and the oxidising power of the active centre.
Electronic Fine‐Tuning of Oxygen Atom Transfer Reactivity of cis‐Dioxomolybdenum(VI) Complexes with Thiosemicarbazone Ligands
Authors: Ducrot Aurélien , Scattergood Bethany , Coulson Ben , Perutz Robin N. , Duhme‐Klair Anne‐K. 
Published: April 2015

AbstractA series of six cis‐dioxomolybdenum(VI) complexes with thiosemicarbazone ligands was synthesized and characterized. The ligands were obtained by reacting ethyl thiosemicarbazide with salicylaldehydes substituted with a selection of electron‐withdrawing and electron‐donating groups. The crystal structures, IR, NMR spectroscopic data and oxygen atom transfer activities of the complexes revealed that the electronic effects of the substituents located in the para‐position of the phenolate donor are transmitted through to the molybdenum center, as reflected by linear relationships between Hammett constants and key properties of the complexes, including the molybdenum–phenolate bond lengths and the coordination shift of the imine proton resonance. Compared with the unsubstituted catalyst, electron‐withdrawing substituents increase the rate of oxygen atom transfer from dimethyl sulfoxide to triphenylphosphine, whereas electron‐donating groups have the opposite effect. The highest rate enhancement was achieved through the introduction of a strongly electron‐withdrawing NO2 substituent in the p‐position of the phenolate donor.
Fluorescence Quenching of a Europium Coordination Compound for the Detection of Trace Amounts of Water: Uncovering the Response Mechanism by Structural Confirmation
Authors: Song Li , Wu Ye‐Wen , Chai Wen‐Xiang , Tao Yin‐Song , Jiang Chang , Wang Qiu‐Hua 
Published: April 2015

AbstractThe coordination compound Eu(DAF)2(NO3)3 (1, DAF = 4,5‐diazafluorene), which shows strong red fluorescence, has been synthesized and characterized. The luminescence‐quenching effect of 1 has been applied to the detection of water in CH3CN. For the first time, the response mechanism has been uncovered through the confirmation of the structure of the resultant nonluminous compound [Eu(NO3)2(H2O)5](NO3)(DAF)2·H2O (2). The replacement of the coordinated DAF ligands by the added water led to quenching of the emission of the EuIII ion and the simultaneous enhancement of the ligand emission. X‐ray powder diffraction and thermogravimetric analyses also confirmed this mechanism. Theoretical calculations by the semi‐empirical method revealed the origin of the absorption spectra of 1. This fluorometric detection of trace amounts of water in CH3CN by 1 is a direct, rapid, and sensitive method.
Synthesis of Diazirine‐Based Photoreactive Saccharin Derivatives for the Photoaffinity Labeling of Gustatory Receptors
Authors: Wang Lei , Yoshida Takuma , Muto Yasuyuki , Murai Yuta , Tachrim Zetryana Puteri , Ishida Akiko , Nakagawa Shiori , Sakihama Yasuko , Hashidoko Yasuyuki , Masuda Katsuyoshi , Hatanaka Yasumaru , Hashimoto Makoto 
Published: April 2015

AbstractSaccharin is one of the most common artificial sweeteners that has a bitter taste at high concentrations. Currently, there are no detailed functional analyses of these gustatory receptors. Therefore, we designed and synthesized photoreactive saccharin derivatives that contain a (trifluoromethyl)diazirinyl moiety at the 5‐ or 6‐position for use as functional analysis tools for photoaffinity labeling.
Synthesis of Robust Precursors for the Controlled Fabrication of (6,6), (8,8), (10,10), and (12,12) Armchair Single‐Walled Carbon Nanotubes
Authors: Mueller Andreas , Amsharov Konstantin Yu. 
Published: April 2015

AbstractWe report an effective strategy for preparing robust precursors for the rational synthesis of helicity‐pure single‐walled carbon nanotubes (SWCNTs) by a surface‐assisted strategy. The approach presented allows simple access to large‐diameter SWCNT precursors. The efficiency of the strategy is demonstrated by the synthesis of four robust precursors for the preparation of (6,6), (8,8), (10,10), and (12,12) armchair SWCNTs. The molecules exhibit a rigid and fully fused structure, which is expected to be important for a highly efficient conversion to CNT seeds and a high yield of the respective helicity‐pure SWCNTs. The presented synthetic approach provides simple access to robust SWCNT precursors that can be “programmed” for virtually any helicity.
Mechano‐sensitive nociceptors are required to detect heat pain thresholds and cowhage itch in human skin
Authors: Weinkauf B. , Dusch M. , van der Ham J. , Benrath J. , Ringkamp M. , Schmelz M. , Rukwied R. 
Published: April 2015

AbstractBackgroundMechano‐sensitive and mechano‐insensitive C‐nociceptors in human skin differ in receptive field sizes and electrical excitation thresholds, but their distinct functional roles are yet unclear.MethodsAfter blocking the lateral femoral cutaneous nerve (NCFL) in eight healthy male subjects (3‐mL Naropin® 1%), we mapped the skin innervation territory being anaesthetic to mechanical pin prick but sensitive to painful transcutaneous electrical stimuli. Such ‘differentially anaesthetic zones’ indicated that the functional innervation with mechano‐sensitive nociceptors was absent but the innervation with mechano‐insensitive nociceptors remained intact. In these areas, we explored heat pain thresholds, low pH‐induced pain, cowhage‐ and histamine‐induced itch, and axon reflex flare.ResultsIn differentially anaesthetic skin, heat pain thresholds were above the cut‐off of 50°C (non‐anaesthetized skin 47 ± 0.4°C). Pain ratings to 30 μL pH 4 injections were reduced compared to non‐anaesthetized skin (48 ± 9 vs. 79 ± 6 VAS; p < 0.01). The axon reflex flare area did not differ between these zones (7.8 ± 1.4 cm2 vs. 8.3 ± 0.5 cm2). Histamine iontophoresis still caused pruritus in differentially anaesthetized skin in five of eight subjects (VAS 26 ± 14), whereas itch upon cowhage spicules was absent (VAS 0 vs. 29 ± 11 in non‐anaesthetized skin).ConclusionsWe conclude that activation of mechano‐insensitive nociceptors is sufficient to provoke itch by histamine‐ and acid‐induced pain. The mechano‐sensitive nociceptors are crucial for cowhage‐induced itch and for the assessment of heat pain thresholds.
The relationship between fear and pain levels during needle procedures in children from the parents' perspective
Authors: Hedén L. , von Essen L. , Ljungman G. 
Published: April 2015

AbstractBackgroundThe primary objective was to determine the levels of and potential relationships between procedure‐related fear and pain in children. Secondary objectives were to determine if there are associations between the child's age and sex, diagnostic group, time since diagnosis, time since last needle insertion, cortisol levels and the parent's fear level in relation to fear and pain.MethodsThe child's level of pain and fear was reported by parents on 0–100 mm visual analogue scales (VAS). One hundred and fifty‐one children were included consecutively when undergoing routine needle insertion into a subcutaneously implanted intravenous port. All children were subjected to one needle insertion following topical anaesthesia (EMLA) application. The effect of the child's age and sex, diagnostic group, time since diagnosis, time since last needle insertion, cortisol change levels and the parent's fear level, on fear and pain levels was investigated with multiple regression analysis.ResultsThe needle‐related fear level (VAS mean 28 mm) was higher than the needle‐related pain level (VAS mean 17 mm) when topical anaesthesia is used according to parents' reports (n = 151, p < 0.001). With fear as the dependent variable, age and pain were significantly associated and explained 33% of the variance, and with pain as the dependent variable, fear, parents' fear and change in cortisol level were significantly associated and explained 38% of the variance.ConclusionsAccording to parents, children experienced more fear than pain during needle insertion when topical anaesthesia is used. Therefore, in addition to pain management, an extended focus on fear‐reducing interventions is suggested for needle procedures.
Electroanalytical Studies of Chromone Based Ionophores for the Selective Determination of Arsenite Ion
Authors: Gupta Neha , Singh Ashok Kumar , Bhardwaj Shubhrajyotsna , Singhal Divya 
Published: April 2015

AbstractTwo chemosensors 4H‐1‐benzopyran‐3‐carboxaldehyde, 4‐oxo‐, 3‐(2‐phenylhydrazone), [I1] and 4H‐1‐benzopyran‐3‐carboxaldehyde, 4‐oxo‐, 3‐[2‐(2,4‐dinitrophenyl)hydrazone], [I2] with hydrazone‐NH group as binding site have been shown excellent selectivity for arsenite ion. It is confirmed by the UV‐vis titration that I2 is more selective than I1. The performance of the coated graphite electrode (CGE) was found to be better than polymeric membrane electrode (PME) in terms of linear range of 4.89×10−7–1.0×10−1 mol L−1, low detection limit of 8.31×10−8 mol L−1 and short response time. The proposed sensors were also used to determine the arsenite ion in different water samples.
Jacobian‐free Newton–Krylov method for implicit time‐spectral solution of the compressible Navier‐Stokes equations
Authors: Attar Peter J. 
Published: April 2015

SummaryWe introduce a Jacobian‐free Newton–Krylov method for the implicit time‐spectral solution of the compressible Navier‐Stokes equations. A new type of preconditioner is presented, which is based upon an approximate factorization of an approximation to the exact time‐spectral Jacobian. The choice of this type of preconditioner is particularly useful when the time‐spectral scheme is to be implemented into a computational code that already contains an implicit time‐marching solver. The spatial discretization of the Navier–Stokes equation consists of a sixth‐order compact scheme with a high‐order, low‐pass filter. Numerical simulation of the laminar flow over a circular cylinder at two post‐critical Reynolds numbers (Re=50,100) is used to characterize the performance of the method. In general, the time‐spectral solution is two to ten times faster, for equivalent accuracy in the lift coefficient, than a time‐marching implicit Beam‐Warming solution with the upper end of this range noted when the Reynolds number is closer to the dynamic instability bifurcation Reynolds number. Other numerical and analytical results are presented, which demonstrate various aspects of the preconditioner performance. In addition, results and discussion are given for some characteristics of time‐spectral solutions for autonomous problems where the fundamental frequency is unknown. Copyright © 2015 John Wiley & Sons, Ltd.
Improving of Micro Porous Layer based on Advanced Carbon Materials for High Temperature Proton Exchange Membrane Fuel Cell Electrodes
Authors: Zamora H. , Cañizares P. , Rodrigo M. A. , Lobato J. 
Published: April 2015

AbstractThis work reports the study of four different carbon materials for their application as carbon material in microporous layers for high temperature proton exchange membrane fuel cells electrodes. The microporous layers were prepared with carbon black (a commercial one, Vulcan XC72), two different carbon nanofibers, CNF, (Ribbon and Platelet structure) and carbon nanospheres, all of them prepared in our lab. The microporous layers were characterized by XRD. The hydrophobicity, electrical conductivity, and permeability to different gases were also evaluated. The stability is an important issue to be overcome in the field of proton exchange membrane fuel cells. Thus, accelerated thermal and electrochemical degradation tests in phosphoric acid media were carried out to evaluate the stability of the different advanced materials tested under the same conditions. From all the performed essays, the carbon nanospheres were the best nano‐carbon materials because of the lower degradation degree shown by the microporous layer prepared with them and the good conductivity and permeability achieved, whereas CNF with a Platelet structure showed a low electrochemical stability due to their greater edge plane exposure which favors their corrosion.
Influence of Pyridine‐Polybenzimidazole Film Thickness of Carbon Nanotube Supported Platinum on Fuel Cell Applications
Authors: Kaewsai D. , Lin H. L. , Yu T. L. 
Published: April 2015

AbstractPyridine‐polybenzimidazole (PyPBI) films of different thickness (∼1.0–2.4 nm) are wrapped on the surfaces of multi‐walled carbon nanotubes (CNTs). To prepare Pt on PyPBI/CNT (Pt‐PyPBI/CNT) catalysts, Pt4+ ions are immobilized on these PyPBI wrapped CNTs (PyPBI/CNTs) via Lewis acid‐base coordination between Pt4+ and :N‐ of imidazole groups, followed by reducing Pt4+ to Pt nanoparticles. The influence of PyPBI film thickness on the Pt particle size, loading and electrochemical surface area, respectively, of Pt‐PyPBI/CNTs is investigated. Fuel cell performances of the PBI/H3PO4 based membrane electrode assemblies (MEAs) prepared from these Pt‐PyPBI/CNT catalysts are also evaluated at 160 °C with unhumidified H2/O2 gases. Among the catalysts, the Pt‐PyPBI/CNT catalyst with a PyPBI film thickness of ∼1.6 nm (which is around half of the Pt particle size), a Pt loading of ∼44 wt.%, and a Pt particle size of ∼3.3 nm exhibits the best fuel cell performance.
Measuring the magnetoelectric effect across scales
Authors: Lupascu Doru C. , Wende Heiko , Etier Morad , Nazrabi Ahmadshah , Anusca Irina , Trivedi Harsh , Shvartsman Vladimir V. , Landers Joachim , Salamon Soma , Schmitz‐Antoniak Carolin 
Published: April 2015

AbstractMagnetoelectric coupling is the material based coupling between electric and magnetic fields without recurrence to electrodynamics. It can arise in intrinsic multiferroics as well as in composites. Intrinsic multiferroics rely on atomistic coupling mechanisms, or coupled crystallographic order parameters, and even more complex mechanisms. They typically require operating temperatures much below T = 0°C in order to exhibit their coupling effects. Room temperature applications are thus excluded. Consequently, composites have been designed to circumvent this limitation. They rely on field coupling between magnetostrictive and piezoelectric materials or in more advanced scenarios on quantum coupling in between both phases.This overview will describe experimental techniques and their particular limitations in accessing these coupling phenomena at different scales. Strain coupling is the dominant coupling mechanism at the macroscale as well as down to the micrometer. At the nanoscale more subtle effects can arise and some care has to be taken when investigating local coupling at interfaces using scanning probe techniques, e. g. due to semiconductor effects, field screening, or gradient and surface effects. At the smallest length scale atomic or molecular coupling can be tested using X‐ray dichroism or probe atoms like 57Fe in Mössbauer spectroscopy. We display a selection of measuring techniques at the different scales and outline possible pitfalls for experimentalists as well as theoreticians when using material parameters extracted from such experimental work. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of phenomenological and laminate‐based models for rate‐dependent switching in ferroelectric continua
Authors: Dusthakar Dinesh Kumar , Menzel Andreas , Svendsen Bob 
Published: April 2015

AbstractThe purpose of the current work is the comparison of a phenomenological and a laminate‐based model for rate‐dependent switching in ferroelectric single crystals. To this end, the phenomenological model formulation of [1] is considered. In this model, the polarization vector is treated as an internal variable. The evolution of the polarization determines the remanent strain; dependence of energy storage on its direction results in generally transverse isotropic material behavior. This is compared here with a laminate‐based model in which the volume fractions of ferroelectric variants are treated as internal variables. The evolution of these volume fractions determines in turn the remanent strain and polarization as volume averages of corresponding ferroelectric variant quantities. Besides a comparison of the respective model formulations, the phenomenological and laminate models are compared in the context of numerical simulation examples. It turns out that both modeling frameworks nicely recapture the underlying dissipative and rate‐dependent effects, which is represented by means of simulated butterfly curves and hysteresis loops under homogeneous loading conditions as well as by finite element simulations. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of beta‐amyloid on face processing in young and old adults: A multivariate analysis of the BOLD signal
Authors: Rieck Jenny R. , Rodrigue Karen M. , Kennedy Kristen M. , Devous Michael D. , Park Denise C. 
Published: April 2015

AbstractThe recent ability to measure in vivo beta‐amyloid (Aβ), a marker of Alzheimer's disease (AD), has led to an increased focus on the significance of Aβ deposition in clinically normal adults. Evidence suggests that healthy adults with elevated cortical Aβ show differences in neural activity associated with memory encoding—specifically encoding of face stimuli. Here, we examined if Aβ deposition in clinically normal adults was related to differences in neural activity in ventral visual cortex during face viewing. Our sample included 23 high‐Aβ older adults, 23 demographically matched low‐Aβ older adults, and 16 young adults. Participants underwent cognitive testing, Aβ positron emission tomography imaging with 18F‐Florbetapir, and functional magnetic resonance imaging to measure neural activity while participants passively viewed photographs of faces. Using barycentric discriminant analysis—a between‐groups classification technique—we found that patterns of neural activity in the left fusiform gyrus, a region highly responsive to faces, distinguished Aβ status of participants. Older adults with elevated Aβ were characterized by decreased activity in left fusiform compared to Aβ‐negative older adults. Further, we found that the degree to which older adults expressed decreased fusiform activity was related to worse performance on tasks of processing speed. Our results provide unique evidence that, in addition to previously studied memory and default regions, decreased neural activity in a region important for face perception was associated with elevated Aβ and may be an early manifestation of AD. Hum Brain Mapp 36:2514–2526, 2015. © 2015 Wiley Periodicals, Inc.
Oral contraceptive pill use is associated with localized decreases in cortical thickness
Authors: Petersen Nicole , Touroutoglou Alexandra , Andreano Joseph M. , Cahill Larry 
Published: April 2015

AbstractOral contraceptive pills (OCs), which are used to prevent pregnancy by the majority of women in the United States, contain steroid hormones that may affect the brain's structure and function. In this investigation, we tested the hypothesis that OC use is associated with differences in brain structure using a hypothesis‐driven, surface‐based approach. In 90 women, (44 OC users, 46 naturally‐cycling women), we compared the cortical thickness of brain regions that participate in the salience network and the default mode network, as well as the volume of subcortical regions in these networks. We found that OC use was associated with significantly lower cortical thickness measurements in the lateral orbitofrontal cortex and the posterior cingulate cortex. These regions are believed to be important for responding to rewards and evaluating internal states/incoming stimuli, respectively. Further investigations are needed to determine if cortical thinning in these regions are associated with behavioral changes, and also to identify whether OC use is causally or only indirectly related to these changes in brain morphology. Hum Brain Mapp 36:2644–2654, 2015. © 2015 Wiley Periodicals, Inc.
Helping Peers Seek Professional Treatment for Depression Among Young South Koreans: An Application of the Theory of Planned Behavior
Authors: Lee Sun Hae , Choi Jung Ah , Park Ji Hye 
Published: April 2015

This study examined the applicability of the theory of planned behavior to understand factors that influence whether young South Koreans help peers with depression to seek professional counseling services. The structural equation modeling on the survey data collected from 191 South Korean students suggests that subjective norms and behavioral control could be salient factors for young South Koreans to take initiative and assist their peers in need of counseling services.Este estudio examinó la aplicabilidad de la teoría del comportamiento planificado para comprender factores que influyen sobre la decisión de jóvenes surcoreanos de ayudar a sus compañeros que sufren de depresión a buscar ayuda profesional a través de servicios de consejería. El modelo de ecuación estructural de los datos de la encuesta recogidos de 191 estudiantes surcoreanos sugiere que las normas subjetivas y el control del comportamiento podrían ser factores destacados para los jóvenes surcoreanos a la hora de tomar la iniciativa y ayudar a sus compañeros que necesitan servicios de consejería.