bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing water resource system vulnerability to unprecedented hydrological drought using copulas to characterize drought duration and deficit
Authors: Borgomeo Edoardo , Pflug Georg , Hall Jim W. , Hochrainer‐Stigler Stefan
Published: October 2015

Global climate models suggest an increase in evapotranspiration, changing storm tracks, and moisture delivery in many parts of the world, which are likely to cause more prolonged and severe drought, yet the weakness of climate models in modeling persistence of hydroclimatic variables and the uncertainties associated with regional climate projections mean that impact assessments based on climate model output may underestimate the risk of multiyear droughts. In this paper, we propose a vulnerability‐based approach to test water resource system response to drought. We generate a large number of synthetic streamflow series with different drought durations and deficits and use them as input to a water resource system model. Marginal distributions of the streamflow for each month are generated by bootstrapping the historical data, while the joint probability distributions of consecutive months are constructed using a copula‐based method. Droughts with longer durations and larger deficits than the observed record are generated by perturbing the copula parameter and by adopting an importance sampling strategy for low flows. In this way, potential climate‐induced changes in monthly hydrological persistence are factored into the vulnerability analysis. The method is applied to the London water system (England) to investigate under which drought conditions severe water use restrictions would need to be imposed. Results indicate that the water system is vulnerable to drought conditions outside the range of historical events. The vulnerability assessment results were coupled with climate model information to compare alternative water management options with respect to their vulnerability to increasingly long and severe drought.
Identifying seasonal patterns of phosphorus storm dynamics with dynamic time warping
Authors: Dupas Rémi , Tavenard Romain , Fovet Ophélie , Gilliet Nicolas , Grimaldi Catherine , Gascuel‐Odoux Chantal
Published: October 2015

Phosphorus (P) transfer during storm events represents a significant part of annual P loads in streams and contributes to eutrophication in downstream water bodies. To improve understanding of P storm dynamics, automated or semiautomated methods are needed to extract meaningful information from ever‐growing water quality measurement data sets. In this paper, seasonal patterns of P storm dynamics are identified in two contrasting watersheds (arable and grassland) through Dynamic Time Warping (DTW) combined with k‐means clustering. DTW was used to align discharge time series of different lengths and with differences in phase, which allowed robust application of a k‐means clustering algorithm on rescaled P time series. In the arable watershed, the main storm pattern identified from autumn to winter displayed distinct export dynamics for particulate and dissolved P, which suggests independent transport mechanisms for both P forms. Conversely, the main storm pattern identified in spring displayed synchronized export of particulate and dissolved P. In the grassland watershed, the occurrence of synchronized export of dissolved and particulate P forms was not related to the season, but rather to the amplitude of storm events. Differences between the seasonal distributions of the patterns identified for the two watersheds were interpreted in terms of P sources and transport pathways. The DTW‐based clustering algorithm used in this study proved useful for identifying common patterns in water quality time series and for isolating unusual events. It will open new possibilities for interpreting the high‐frequency and multiparameter water quality time series that are currently acquired worldwide.
High‐Performance Integrated Control of water quality and quantity in urban water reservoirs
Authors: Galelli S. , Castelletti A. , Goedbloed A.
Published: October 2015

This paper contributes a novel High‐Performance Integrated Control framework to support the real‐time operation of urban water supply storages affected by water quality problems. We use a 3‐D, high‐fidelity simulation model to predict the main water quality dynamics and inform a real‐time controller based on Model Predictive Control. The integration of the simulation model into the control scheme is performed by a model reduction process that identifies a low‐order, dynamic emulator running 4 orders of magnitude faster. The model reduction, which relies on a semiautomatic procedural approach integrating time series clustering and variable selection algorithms, generates a compact and physically meaningful emulator that can be coupled with the controller. The framework is used to design the hourly operation of Marina Reservoir, a 3.2 Mm3 storm‐water‐fed reservoir located in the center of Singapore, operated for drinking water supply and flood control. Because of its recent formation from a former estuary, the reservoir suffers from high salinity levels, whose behavior is modeled with Delft3D‐FLOW. Results show that our control framework reduces the minimum salinity levels by nearly 40% and cuts the average annual deficit of drinking water supply by about 2 times the active storage of the reservoir (about 4% of the total annual demand).
Difunctional Graphene–Fe3O4 Hybrid Nanosheet/Polydimethylsiloxane Nanocomposites with High Positive Piezoresistive and Superparamagnetism Properties as Flexible Touch Sensors
Authors: Zha Jun‐Wei , Huang Wei , Wang Si‐Jiao , Zhang Dong‐Li , Li Robert K. Y. , Dang Zhi‐Min
Published: October 2015

Functional materials with excellent electrical and magnetic properties have a potential application in most high‐tech fields. Here, superparamagnetic graphene–Fe3O4 (G–F) nanosheet hybrids are prepared by a facile one‐step hydrothermal process, which will beneficial to well combine with various polymer matrix to get binary functional composites. Polydimethylsiloxane (PDMS) nanocomposites filled with G–F nanosheets are prepared by a three rolling method. The microstructures of G–F nanosheets as well as the electrical, piezoresistive, and magnetic properties of the G–F/PDMS nanocomposites are investigated. Slightly above the percolation threshold (    fc = 3.4 wt%), the G–F/PDMS nanocomposites with 3.65 wt% of G–F nanosheets show a high conductivity, which is about 10 orders of magnitudes higher than that of pure PDMS, showing an obvious insulator–semiconductor transition. Moreover, the resistance of the nanocomposites with G–F filler near the percolation threshold exponentially increases with the uniaxial pressure. The normalized resistance (R/R0) can reach up to 870 at 0.88 MPa with 3.65 wt% G–F nanosheets loading. The G–F/PDMS nanocomposites also show superparamagnetism with saturation magnetization values of 0.21 emu g−1. These results suggest that the G–F/PDMS nanocomposites in this work provide a new route to fabricate difunctional polymer‐based nanocomposites with a potential application as flexible touch sensors.
Biomedical Applications of Functionalized ZnO Nanomaterials: from Biosensors to Bioimaging
Authors: Zhu Ping , Weng Zhengyang , Li Xia , Liu Xiangmei , Wu Shuilin , Yeung K. W. K. , Wang Xianbao , Cui Zhenduo , Yang Xianjin , Chu Paul. K.
Published: October 2015

The richness of the structures and properties of members of the ZnO‐based nanostructure family endows these materials with diverse functionalities. In the last decade, the great potential of ZnO‐based nanostructures for biomedical applications due to their unique electronic, optical, catalytical, and antimicrobial properties, as well as their excellent biocompatibility, has been recognized. The ever‐deteriorating environment and the rapidly aging population have given rise to an increase in diseases, healthcare concerns and medical costs, particularly in developing countries, which has led to a high demand for better and lower‐cost biomedical devices with novel biofunctionalities. Here, we review the recent advances in research on nanostructured ZnO‐based biomaterials that have been developed for biomedical applications, such as in biosensorsing, tissue regeneration, bioimaging and drug delivery.
Photowritable Silver‐Containing Phosphate Glass Ribbon Fibers
Authors: Danto Sylvain , Désévédavy Frédéric , Petit Yannick , Desmoulin Jean‐Charles , Abou Khalil Alain , Strutynski Clément , Dussauze Marc , Smektala Frédéric , Cardinal Thierry , Canioni Lionel
Published: October 2015

Tailored silver‐containing zinc‐phosphate glasses possess excellent thermoviscous ability and optical properties. Beyond they have proven to form a favorable matrix for the direct laser writing of photoluminescent and nonlinear patterns. Here, bringing together the merits of these materials with fiber optic technology, the first photosensitive, photowritable silver‐containing glass ribbon fibers are reported. These novel devices are thermally scaled‐down in a homothetic fashion from a macroscopic preform to produce tens‐of‐meters of continuous structure. It is demonstrated that luminescence properties of the native glass are preserved after the shaping process. Furthermore it is established that the unique fiber's flat geometry allows for the convenient, accurate laser writing of complex luminescent silver clusters patterns within the glass matrix. It is believed that the drawing of silver‐containing zinc‐phosphate glasses could lead to a decisive breakthrough in the field of photosensitive fibers. They would offer a promising platform for the design of highly efficient sensing devices based on amplified optical processes effects, for metamaterials or as fundamental bricks for photonics.
Synthesis of ortho‐(Fluoro)alkylated Pyridines via Visible Light‐Promoted Radical Isocyanide Insertion
Authors: Tong Kun , Zheng Tianyi , Zhang Yan , Yu Shouyun
Published: October 2015

A regiospecific synthesis of ortho‐trifluoromethylated and ortho‐(fluoro)alkylated pyridine derivatives has been developed. This strategy is enabled by visible light‐promoted vinyl isocyanide insertions with Umemoto’s reagent and electron‐deficient bromides at room temperature. The methodology presented here provides an access to highly functionalized ortho‐(fluoro)alkylated pyridine derivatives regiospecifically under mild conditions with good yields. The proposed mechanism was supported by TEMPO trapping experiments, Stern–Volmer analysis and light off/on and time profile experiments.

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Stretchable and Transparent Organic Semiconducting Thin Film with Conjugated Polymer Nanowires Embedded in an Elastomeric Matrix
Authors: Song Eunjoo , Kang Boseok , Choi Hyun Ho , Sin Dong Hun , Lee Hyochan , Lee Wi Hyoung , Cho Kilwon
Published: October 2015

Despite the considerable efforts applied toward developing stretchable electronics, few intrinsically stretchable semiconductors have been reported that retain the original electrical characteristics under stretching. This study introduces an intrinsically stretchable and transparent organic semiconducting layer by blending self‐assembled nanowires (NWs) of an organic semiconductor with an elastomeric and transparent polymer. Blends of poly(3‐hexylthiophene) (P3HT) NWs and poly(dimethylsiloxane) (PDMS) yield P3HT NW networks embedded in the PDMS matrix. Interestingly, it is found that the vertical distribution of P3HT NWs in the blend films is sensitive to the surface characteristics of the underlying substrate. Compared to the P3HT NWs distributed on a Si substrate with vertical gradation, the P3HT NWs are evenly distributed throughout the PDMS matrix on a PDMS substrate. Organic transistors prepared with the blend active layers with various P3HT ratios exhibit device performances comparable to those of a device prepared with homo‐P3HT NWs, even at 1 wt% P3HT, due to the formation of percolated networks of the P3HT NWs with a high crystallinity and a large aspect ratio. This blend active layer shows the superior electrical and mechanical properties during stretching at high strains unlike the homo‐P3HT NW system.
Quantum exclusion of positive cosmological constant?
Authors: Dvali Gia , Gomez Cesar
Published: October 2015

We show that a positive cosmological constant is incompatible with the quantum‐corpuscular resolution of de Sitter metric in form of a coherent state. The reason is very general and is due to the quantum self‐destruction of the coherent state as a result of the scattering of constituent graviton quanta. This process creates an irreversible quantum clock, which precludes eternal de Sitter. It also eliminates the possibility of Boltzmann brains and Poincare recurrences. This effect is expected to be part of any microscopic theory that takes into account the quantum corpuscular structure of the cosmological background. This observation puts the cosmological constant problem in a very different light, promoting it, from a naturalness problem, into a question of quantum consistency. We are learning that quantum gravity cannot tolerate exceedingly‐classical sources.
Oxygen Reduction with a Bifunctional Iridium Dihydride Complex
Authors: Schiwek Christoph , Meiners Jenni , Förster Moritz , Würtele Christian , Diefenbach Martin , Holthausen Max C. , Schneider Sven
Published: October 2015

The iridium dihydride [Ir(H)2(HPNP)]+ (PNP=N(CH2CH2PtBu2)2) reacts with O2 to give the unusual, square‐planar iridium(III) hydroxide [Ir(OH)(PNP)]+ and water. Regeneration of the dihydride with H2 closes a quasi‐catalytic synthetic oxygen‐reduction reaction (ORR) cycle that can be run several times. Experimental and computational examinations are in agreement with an oxygenation mechanism via rate‐limiting O2 coordination followed by H‐transfer at a single metal site, facilitated by the cooperating pincer ligand. Hence, the four electrons required for the ORR are stored within the two covalent MH bonds of a mononuclear metal complex.
Trapping the δ Isomer of the Polyoxometalate‐Based Keggin Cluster with a Tripodal Ligand
Authors: Sartzi Harikleia , Miras Haralampos N. , Vilà‐Nadal Laia , Long De‐Liang , Cronin Leroy
Published: October 2015

We report the synthesis, structural, and electronic characterization of the theoretically predicted, but experimentally elusive δ‐isomer of the Keggin polyoxometalate polyanion. A family of δ‐Keggin polyoxoanions of the general formula, (TEA)HpNaq [H2M12(XO4)O33(TEA)]⋅r H2O where p, q, r=[2,3,8] for 1 and [4,1,4] for 2 were isolated by the reaction of tungstate(VI) and vanadium(V) with triethanolammonium ions (TEAH), acting as a tripodal ligand grafted to the surface of the cluster thereby stabilizing the polyanionic δ‐Keggin archetype. The δ‐Keggin species were characterized by single‐crystal X‐ray diffraction, FT‐IR, UV/Vis, NMR, and ESI‐MS spectrometry. Electronic structure and structure–stability correlations were evaluated by means of DFT calculations. The compounds exhibited multi‐electron transfer and reversible photochromic properties by undergoing single‐crystal‐to‐single‐crystal (SC–SC) transformations accompanied with color changes under light.
High‐contrast Noninvasive Imaging of Kidney Clearance Kinetics Enabled by Renal Clearable Nanofluorophores
Authors: Yu Mengxiao , Liu Jinbin , Ning Xuhui , Zheng Jie
Published: October 2015

Noninvasive imaging of kidney clearance kinetics (KCK) of renal clearable probes is key to studying unilateral kidney function diseases, but such imaging is highly challenging to achieve with in vivo fluorescence. While this long‐standing challenge is often attributed to the limited light penetration depth, we found that rapid and persistent accumulation of conventional dyes in the skin “shadowed” real fluorescence signals from the kidneys and prevented noninvasive imaging of KCK, which, however, can be addressed with renal clearable nanofluorophores. By integrating near infrared emission with efficient renal clearance and ultralow background interference, the nanofluorophores can increase kidney‐contrast enhancement and imaging‐time window by approximately 50‐ and 1000‐fold over conventional dyes, and significantly minimize deviation between noninvasive and invasive KCK, laying down a foundation for translating in vivo fluorescence imaging in preclinical noninvasive kidney function assessments.
The Origin of Life—Out of the Blue
Authors: Sutherland John D.
Published: October 2015

Either to sustain autotrophy, or as a prelude to heterotrophy, organic synthesis from an environmentally available C1 feedstock molecule is crucial to the origin of life. Recent findings augment key literature results and suggest that hydrogen cyanide—“Blausäure”—was that feedstock.
Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts
Authors: Yoneda Naoki , Fukata Yukihiro , Asano Keisuke , Matsubara Seijiro
Published: October 2015

Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product.
19F Paramagnetic Relaxation Enhancement: A Valuable Tool for Distance Measurements in Proteins
Authors: Matei Elena , Gronenborn Angela M.
Published: October 2015

Fluorine NMR paramagnetic relaxation enhancement was evaluated as a versatile approach for extracting distance information in selectively F‐labeled proteins. Proof of concept and initial applications are presented for the HIV‐inactivating lectin cyanovirin‐N. Single F atoms were introduced at the 4‐, 5‐, 6‐ or 7 positions of Trp49 and the 4‐position of Phe4, Phe54, and Phe80. The paramagnetic nitroxide spin label was attached to Cys residues that were placed into the protein at positions 50 or 52. 19F‐T2 NMR spectra with different relaxation delays were recorded and the transverse 19F‐PRE rate, 19F‐Γ2, was used to determine the average distance between the F nucleus and the paramagnetic center. Our data show that experimental 19F PRE‐based distances correspond to 0.93 of the 1HN‐PRE distances, in perfect agreement with the gyromagnetic γ19F/γ1H ratio, thereby demonstrating that 19F PREs are excellent alternative parameters for quantitative distance measurements in selectively F‐labeled proteins.
Computational optimal control of the Saint–Venant PDE model using the time‐scaling technique
Authors: Chen Tehuan , Xu Chao
Published: October 2015

This paper proposes a new time‐scaling approach for computational–optimal control of a distributed parameter system governed by the Saint–Venant partial differential equations (PDEs). We propose the time‐scaling approach that can change a uniform time partition to a nonuniform one. We also derive the gradient formulas by using the variational method. Then, the method of lines is applied to compute the Saint–Venant PDEs after implementing the time‐scaling transformation and the associate costate PDEs. Finally, we compare the optimization results using the proposed time‐scaling approach with the one not using it. The simulation result demonstrates the effectiveness of the proposed time‐scaling method. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.
IDENTIFICATION OF THE FGL‐AMIDE ALLATOSTATIN GENE OF THE PRIMITIVE TERMITE Mastotermes darwiniensis AND THE WOODROACH Cryptocercus darwini
Authors: Wende Franziska , Meyering‐Vos Martina , Hoffmann Klaus H.
Published: October 2015

Allatostatins with the C‐terminal ending Tyr/Phe‐Xaa‐Phe‐Gly‐Leu/Ile‐amide (FGLa/ASTs) are widespread neuropeptides with multiple functions. The gene encoding the FGLa/AST polypeptide precursor was first isolated from cockroaches and since then could be identified in many insects and crustaceans. With its strictly conserved regions in combination with variable regions the gene seems to be a good candidate for phylogenetic analyses between closely and distantly related species. Here, the structure of the FGLa/AST gene of the most primitive termite, the giant northern termite Mastotermes darwiniensis Froggatt, was identified. The FGLa/AST gene of the woodroach Cryptocercus darwini was also determined. Precursor sequences of both species possess the general organization of dictyopteran FGLa/AST precursors containing 14 putative FGLa/AST peptides. In M. darwiniensis, only 11 out of the 14 FGLa/AST‐like peptides possess the C‐terminal conserved region Y/FXFGL/I/V/M and four of the putative peptide structures are not followed by a Gly residue that would lead to nonamidated peptides. Phylogenetic analyses show the high degree of similarity of dictyopteran FGLa/AST sequences. The position of termites, nested within the Blattaria, confirms that termites have evolved from primitive cockroaches.
H∞Fuzzy State‐Feedback Control Plus State‐Derivative‐Feedback Control Synthesis for Photovoltaic Systems
Authors: Kaewpraek Nikorn , Assawinchaichote Wudhichai
Published: October 2015

This paper addresses the problem of designing an H∞fuzzy state‐ feedback (SF) plus state‐derivative‐feedback (SDF) control system for photovoltaic (PV) systems based on a linear matrix inequality (LMI) approach. The TS fuzzy controller is designed on the basis of the Takagi‐Sugeno (TS) fuzzy model. The sufficient condition is found such that the system with the fuzzy controller is asymptotically stable and an H∞performance is satisfied. First, a dc/dc buck converter is considered to regulate the power output by controlling state and state‐derivative variables of PV systems. The dynamic model of PV systems is approximated by the TS fuzzy model in the form of nonlinear systems. Then, based on a well‐known Lyapunov functional approach, the synthetic is formulated of an H∞fuzzy SF plus SDF control law, which guarantees the L2‐gain from an exogenous input to the regulated output to be less than or equal to some prescribed value. Finally, to show effectiveness, the simulation of the PV systems with the proposed control is assessed by the computer programme. The proposed control method shows good performance for power output and high stability for the PV system.
Bladder cancer and occupational exposure to diesel and gasoline engine emissions among Canadian men
Authors: Latifovic Lidija , Villeneuve Paul J. , Parent Marie‐Élise , Johnson Kenneth C. , Kachuri Linda ,   the Canadian Cancer Registries Epidemiology Group, Harris Shelley A.
Published: October 2015

The International Agency for Research on Cancer has classified diesel exhaust as a carcinogen based on lung cancer evidence; however, few studies have investigated the effect of engine emissions on bladder cancer. The purpose of this study was to investigate the association between occupational exposure to diesel and gasoline emissions and bladder cancer in men using data from the Canadian National Enhanced Cancer Surveillance System; a population‐based case–control study. This analysis included 658 bladder cancer cases and 1360 controls with information on lifetime occupational histories and a large number of possible cancer risk factors. A job‐exposure matrix for engine emissions was supplemented by expert review to assign values for each job across three dimensions of exposure: concentration, frequency, and reliability. Odds ratios (OR) and their corresponding 95% confidence intervals were estimated using logistic regression. Relative to unexposed, men ever exposed to high concentrations of diesel emissions were at an increased risk of bladder cancer (OR = 1.64, 0.87–3.08), but this result was not significant, and those with >10 years of exposure to diesel emissions at high concentrations had a greater than twofold increase in risk (OR = 2.45, 1.04–5.74). Increased risk of bladder cancer was also observed with >30% of work time exposed to gasoline engine emissions (OR = 1.59, 1.04–2.43) relative to the unexposed, but only among men that had never been exposed to diesel emissions. Taken together, our findings support the hypothesis that exposure to high concentrations of diesel engine emissions may increase the risk of bladder cancer.
Inhibition of UV‐induced matrix metabolism by a myristoyl tetrapeptide
Authors: Kwon Haeyoung , Ahn Eunsook , Kim Seon‐Young , Kang YeoHong , Kim Myung Ok , Jin Byung Suk , Park Seyeon
Published: October 2015

Regulation of extracellular matrix (ECM) composition is important in tissue homeostasis and function. We screened small peptides for their ability to inhibit ultraviolet (UV)‐induced cell metabolism in epidermal fibroblasts. We found that UV irradiation increased matrix metalloproteinase (MMP) expression and inflammatory gene expression in human Hs68 fibroblast cells. We also demonstrated that a myristoyl tetrapeptide with the amino acid sequence Gly‐Leu‐Phe‐Trp (mGLFW) suppressed the UV‐induced expression of MMPs and inflammatory genes. Moreover, mGLFW stimulated the expression of ECM proteins in Hs68 fibroblasts. In order to provide the mechanism of action for mGLFW, we investigated UV‐induced signaling changes in the presence of mGLFW using a cDNA microarray. UV exposure increased the expression of MMP genes, such as MMP1, MMP3, and MMP14, and inflammation‐related genes, including interleukin 1 receptor and peroxisome proliferator‐activated receptor gamma (PPARγ). Treatment with mGLFW abrogated the UV‐induced expression of MMP‐related genes and inflammatory genes. In addition, mGLFW increased the expression of collagen genes, including COL1A1, COL1A2, and COL5A1. We examined whether the activation of AP‐1, a UV‐activated transcription factor, is suppressed by mGLFW. The results demonstrated that AP‐1 expression increased upon UV exposure and that this expression was inhibited by mGLFW. In conclusion, our results demonstrate that mGLFW reversed the effects of UV exposure by enhancing the expression of collagen proteins and suppressing the expression of MMPs, which degrade the ECM.
Dendritic Chiral Salen Titanium(IV) Catalysts Enforce the Cooperative Catalysis of Asymmetric Sulfoxidation
Authors: Chen Yaju , Tan Rong , Zhang Yaoyao , Zhao Guangwu , Yin Donghong
Published: October 2015

A series of new dendritic chiral salen TiIV catalysts was prepared by the covalent confinement of multiple chiral salen TiIV complexes on the periphery of a polyamidoamine (PAMAM) dendrimer through a flexible ionic liquid (IL) linker. The characterization results suggested the presence of a dendritic PAMAM scaffold, IL spacer, and intact peripheral active sites in the catalysts. The unique dendritic structure of catalysts together with a flexible IL spacer enforced the intramolecular, cooperative catalysis of asymmetric sulfoxidation to result in improved catalytic efficiency and, especially, a remarkably high selectivity. A chemoselectivity of 90 % with an enantioselectivity of 85 % was obtained in the asymmetric sulfoxidation of methyl phenyl sulfide catalyzed by the dendritic catalyst, which was significantly higher than that observed for the neat complex (64 % chemoselectivity with 68 % enantioselectivity). Furthermore, the catalysts could be recovered easily by solvent precipitation for efficient reuse.
Selection of Highly SERS‐Active Nanostructures from a Size Gradient of Au Nanovoids on a Single Bipolar Electrode
Authors: Kayran Yasin U. , Eßmann Vera , Grützke Stefanie , Schuhmann Wolfgang
Published: October 2015

As surface‐enhanced Raman scattering (SERS) crucially depends on the morphology of nanostructured metal surfaces, we developed a convenient approach to produce a size gradient of truncated spherical Au nanovoids on a single bipolar electrode. The continuous potential drop in solution implies a linearly changing interfacial potential difference at the wireless electrode, leading to a linearly changing rate of Au electrodeposition. Such a structural gradient enables fast and reproducible screening for those structures, evoking high SERS intensity in a particular experiment. The optimal Au deposition potential with respect to the highest SERS amplification was determined and applied for the fabrication of highly active SERS substrates.
Cyanoacetic Acid as a Masked Electrophile: Transition‐Metal‐Free Cyanomethylation of Amines and Carboxylic Acids
Authors: Wang Hongxiang , Shao Ying , Zheng Hao , Wang Hanghang , Cheng Jiang , Wan Xiaobing
Published: October 2015

Using cyanoacetic acid as a masked electrophile, a new cyanomethylation reaction of amines and carboxylic acids was developed, producing a variety of α‐aminonitriles and cyanomethyl esters with good yields and excellent functionality tolerance. This protocol features simple manipulation, inexpensive reagents, and a wide substrate scope. Iodoacetonitrile was generated in situ from the iodination–decarboxylation of cyanoacetic acid in this transformation.
Facile Aluminum Reduction Synthesis of Blue TiO2 with Oxygen Deficiency for Lithium‐Ion Batteries
Authors: Zheng Jing , Ji Guangbin , Zhang Peng , Cao Xingzhong , Wang Baoyi , Yu Linhui , Xu Zhichuan
Published: October 2015

An ultrafacile aluminum reduction method is reported herein for the preparation of blue TiO2 nanoparticles (donated as Al–TiO2, anatase phase) with abundant oxygen deficiency for lithium‐ion batteries. Under aluminum reduction, the morphology of the TiO2 nanosheets changes from well‐defined rectangular into uniform round or oval nanoparticles and the particle size also decreases from 60 to 31 nm, which can aggressively accelerate the lithium‐ion diffusion. Electron paramagnetic resonance (EPR) and positron annihilation lifetime spectroscopy (PALS) results reveal that plentiful oxygen deficiencies relative to the Ti3+ species were generated in blue Al–TiO2; this effectively enhances the electron conductivity of the TiO2. X‐ray photoelectron spectrometry (XPS) analysis indicates that a small peak is observed for the AlO bond, which probably plays a very important role in the stabilization of the oxygen deficiencies/Ti3+ species. As a result, the blue Al–TiO2 possesses significantly higher capacity, better rate performance, and a longer cycle life than the white pure TiO2. Such improvements can be attributed to the decreased particle size, as well as the existence of the oxygen deficiencies/Ti3+ species.
Synthesis of Hydroxypyrrolone Carboxamides Employing Selectfluor
Authors: Allmann Tim Carlo , Moldovan Rares‐Petru , Jones Peter G. , Lindel Thomas
Published: October 2015

Reaction of pyrrole‐2‐carboxamides with Selectfluor in MeCN/water (4:1) affords 2‐hydroxy‐5‐oxopyrrole‐2‐carboxamides in yields of up to 80 %. A variety of sensitive functional groups is tolerated, among them aldehydes and alkynes. The new method also works in the presence of allyl groups and appears to be superior to the use of singlet oxygen. Reaction of the monobrominated dihydropyrrolo[1,2‐a]pyrazinone mukanadin C and its nonbrominated analogue afforded bicyclic hydroxypyrrolones. These compounds are interesting as they constitute a partial structure of the marine natural product oxocyclostylidol.
Thickness‐Dependent Charge Carrier Dynamics in CdSe/ZnSe/CdS Core/Barrier/Shell Nanoheterostructures
Authors: Yadav Sushma , Chowdhury Apurba , Sapra Sameer
Published: October 2015

We report the synthesis of CdSe/ZnSe/CdS heterostructures composed of type I and type II band alignments, where ZnSe acts as a barrier for charge carriers between the CdSe core and the CdS shell as well as being an active component of the type I (CdSe/ZnSe) and type II (ZnSe/CdS) structure simultaneously. We investigated the effect of the thickness of the barrier and the shell on the charge carrier dynamics by using UV/Vis absorbance, photoluminescence (PL), and time‐resolved fluorescence techniques. The experimental data are supported by simple theoretical calculations based on effective mass approximation (EMA). PL results indicate the emission from both type I and type II structures. Time‐resolved fluorescence studies show that the lifetime of the core emission decreases with increasing barrier width, owing to a greater confinement of the exciton to the core, whereas it increases with shell width because of the tunneling of charge carriers, primarily electrons, delaying the recombination of the exciton. The lifetime of the shell emission decreases with shell width as well as barrier width and height, with a larger effect being observed for the barrier width and negligible for the associated changes in the barrier height.
In Situ Raman Monitoring of Silver(I)‐Aided Laser‐Driven Cleavage Reaction of Cyclobutane
Authors: Chen Dengtai , Han Xijiang , Du Yunchen , Wang Hsing‐Lin , Xu Ping
Published: October 2015

The cyclobutane cleavage reaction is an important process and has received continuous interest. Herein, we demonstrate the visible laser‐driven cleavage reaction of cyclobutane in crystal form by using in situ Raman spectroscopy. Silver(I) coordination‐induced strain and thermal effects from the laser irradiation are the two main driving forces for the cleavage of cyclobutane crystals. This work may open up a new avenue for studying cyclobutane cleavage reactions, as compared to the conventional routes using ex situ techniques.
Sex‐specific genetic differences in endurance swimming of Trinidadian guppies
Authors: Gordon Swanne P. , Chen Yun Yi , Yamashita Karalynn , Bejar Christopher , Wilshire Adam , Cheung Vinson
Published: October 2015

Swim performance is considered a main fitness‐determining trait in many aquatic organisms. Swimming is generally the only way most aquatic prey can escape predation, and swimming capacity is directly linked to food capture, habitat shifts, and reproduction. Therefore, evolutionary studies of swim performance are important to understand adaptation to aquatic environments. Most studies, however, concentrate on the importance of burst‐swim responses to predators, and little is known about its effect on endurance. Even fewer studies associate differences in organism swim capabilities to key gender‐specific responses. In this experiment, we assess the gender‐specific genetic basis of swimming endurance among four different populations of Trinidadian guppies adapted to different predation regimes. Our results show that second‐generation common‐garden females adapted to a low‐predation environment show longer swim endurance than fish adapted to a high‐predation environment. We also find an expected effect of lowered swimming endurance during pregnancy, but interestingly, it did not matter whether the females were in advanced stages of pregnancy, which severely changes body morphology, versus mid‐pregnancy. Males did not show the same trends across populations, and overall had lower swim endurances than female fish combined even when accounting for size differences. Populations recently transplanted from high‐ to low‐predation environments showed similar endurance to natural low‐predation environments in one population but not the other. This study highlights the importance of endurance in the adaptation of aquatic organisms to different predation regimes.
How to describe species richness patterns for bryophyte conservation?
Authors: Hespanhol Helena , Cezón Katia , Felicísimo Ángel M. , Muñoz Jesús , Mateo Rubén G.
Published: October 2015

A large amount of data for inconspicuous taxa is stored in natural history collections; however, this information is often neglected for biodiversity patterns studies. Here, we evaluate the performance of direct interpolation of museum collections data, equivalent to the traditional approach used in bryophyte conservation planning, and stacked species distribution models (S‐SDMs) to produce reliable reconstructions of species richness patterns, given that differences between these methods have been insufficiently evaluated for inconspicuous taxa. Our objective was to contrast if species distribution models produce better inferences of diversity richness than simply selecting areas with the higher species numbers. As model species, we selected Iberian species of the genusGrimmia(Bryophyta), and we used four well‐collected areas to compare and validate the following models: 1) four Maxent richness models, each generated without the data from one of the four areas, and a reference model created using all of the data and 2) four richness models obtained through direct spatial interpolation, each generated without the data from one area, and a reference model created with all of the data. The correlations between the partial and reference Maxent models were higher in all cases (0.45 to 0.99), whereas the correlations between the spatial interpolation models were negative and weak (−0.3 to −0.06). Our results demonstrate for the first time that S‐SDMs offer a useful tool for identifying detailed richness patterns for inconspicuous taxa such as bryophytes and improving incomplete distributions by assessing the potential richness of under‐surveyed areas, filling major gaps in the available data. In addition, the proposed strategy would enhance the value of the vast number of specimens housed in biological collections.
Flood water legacy as a persistent source for riparian vegetation during prolonged drought: an isotopic study of Arundo donax on the Rio Grande
Authors: Moore Georgianne , Li Fan , Kui Li , West Jason
Published: October 2015

Invasive riparian plants along arid and semi‐arid rivers are thought to accelerate stream flow recession rates during drought. However, the fraction of river water used directly by plants is unknown. Riparian water sources for plants may also include shallow groundwater, which may differ from the river itself, or water from the unsaturated zone originating from localized rain events or prior floods. Floods that saturate the soil may persist as a lasting legacy to sustain plants over longer time scales. In this study, we examined potential sources of water used by Giant Reed (Arundo donax L.) following a flood and subsequent prolonged drought using natural‐abundance stable isotopes of oxygen (δ18O) and hydrogen (δ2H). River and rain water, groundwater, soil, and rhizome samples were collected along four approximately 100‐m transects perpendicular to the Rio Grande River in southwest Texas. Our observations coincided with a major flood that saturated soils in July of 2010 followed by extreme drought through fall of 2011. Our results showed that the isotope ratio of rhizome water was consistent with prolonged utilization of flood water, which persisted within flood‐recharged surface soils throughout the following summer. Apparently, groundwater was not the dominant source for A. donax when soil moisture was sufficient for plant uptake following a flood. While hydrogeology of rivers vary, this finding highlights the potential for floodwater to sustain riparian vegetation for prolonged periods without rainfall and demonstrates that this may be an important alternative source of water that is not currently accounted for in hydrologic models. Copyright © 2015 John Wiley & Sons, Ltd.
Crystal Structure Relation between Tetragonal and Orthorhombic CsAlD4: DFT and Time‐of‐Flight Neutron Powder Diffraction Studies
Authors: Bernert Thomas , Krech Daniel , Kockelmann Winfried , Felderhoff Michael , Frankcombe Terry J. , Weidenthaler Claudia
Published: October 2015

The crystal structures of orthorhombic and tetragonal CsAlD4 were refined from time‐of‐flight neutron powder diffraction data starting from atomic positions predicted from DFT calculations. The earlier proposed crystal structure of orthorhombic CsAlH4 is confirmed. For tetragonal CsAlH4, DFT calculations predicted a crystal structure in I41/amd as potential minimum structure, while from neutron diffraction studies of CsAlD4 best refinement is obtained for a disordered structure in the space group I41/a, with a = 5.67231(9) Å, c = 14.2823(5) Å. While the caesium atoms are located on the Wyckoff position 4b and aluminium at Wyckoff position 4a, there are two distinct deuterium positions at the Wyckoff position 16f with occupancies of 50 % each. From this structure, the previously reported phase transition between the orthorhombic and tetragonal polymorphs could be explained.
Tandem Claisen Rearrangement/6‐endo Cyclization Approach to Allylated and Pren­ylated Chromones
Authors: Schmidt Bernd , Riemer Martin , Schilde Uwe
Published: October 2015

Allyl, dimethylallyl and prenyl ethers derived from o‐acylphenols reacted upon microwave irradiation to form C‐allylated or ‐prenylated chromone derivatives, depending on the substitution pattern of the arene and the allyl substituent. The reaction proceeds through a tandem Claisen rearrangement and 6‐endo‐trig or 6‐endo‐dig cyclization sequence. For prenyl ethers, the tandem sequence can be extended by a Cope rearrangement to furnish 6‐prenylchromones. The method is potentially useful for the synthesis of natural products and drugs.
Running safety assessment of trains moving over bridges subjected to moderate earthquakes
Authors: Montenegro P. A. , Calçada R. , Vila Pouca N. , Tanabe M.
Published: October 2015

A study about the running safety of trains moving over bridges subjected to earthquakes is presented. The study focuses on moderate earthquakes with relatively small return periods and high probability of occurrence. The analyses are performed using a nonlinear train‐bridge interaction method proposed by the authors, being the running safety evaluated with safety criteria existent in the literature. The influence on the train running safety of the seismic intensity levels, train running speed, and track quality is evaluated. Because no significant nonlinearity is likely to be exhibited in the columns for moderate levels of seismicity, the analyses are performed in the elastic domain. However, the reduction in the columns stiffness due to cracking is accounted, and a methodology to compute their effective stiffness is proposed. Copyright © 2015 John Wiley & Sons, Ltd.
Persistent hepatitis C viral replication despite priming of functional CD8+ T cells by combined therapy with a vaccine and a direct‐acting antiviral
Authors: Callendret Benoit , Eccleston Heather B. , Satterfield William , Capone Stefania , Folgori Antonella , Cortese Riccardo , Nicosia Alfredo , Walker Christopher M.
Published: October 2015

Exhaustion of antiviral CD8+ T cells contributes to persistence of hepatitis C viral (HCV) infection. This immune response has proved difficult to restore by therapeutic vaccination, even when HCV replication is suppressed using antiviral regimens containing type I interferon. Because immunomodulatory effects of type I interferon may be a factor in poor T‐cell priming, we undertook therapeutic vaccination in two chronically infected chimpanzees during treatment with a direct‐acting antiviral (DAA) targeting the HCV NS5b polymerase protein. Immunization with genetic vaccines encoding the HCV NS3‐NS5b nonstructural proteins during DAA treatment resulted in a multifunctional CD8+ T‐cell response. However, these antiviral CD8+ T cells did not prevent persistent replication of DAA‐resistant HCV variants that emerged during treatment. Most vaccine‐induced CD8+ T cells targeted class I epitopes that were not conserved in the circulating virus. Exhausted intrahepatic CD8+ T‐cell targeting‐conserved epitopes did not expand after vaccination, with a notable exception. A sustained, multifunctional CD8+ T‐cell response against at least one intact class I epitope was detected in blood after vaccination. Persistence of HCV was not due to mutational escape of this epitope. Instead, failure to control HCV replication was likely caused by localized exhaustion in the liver, where CD8+ T‐cell expression of the inhibitory receptor programmed cell death 1 increased 25‐fold compared with those in circulation.
Conclusion:
Treatment with a DAA during therapeutic vaccination provided transient control of HCV replication and a multifunctional T‐cell response, primarily against nonconserved class I epitopes; exhaustion of liver‐infiltrating CD8+ T cells that target conserved epitopes may not be averted when DAA therapy fails prematurely due to emergence of resistant HCV variants. (Hepatology 2016;63:1442‐1454)
Mitochondrial oxidative stress and dysfunction in arsenic neurotoxicity: A review
Authors: Prakash Chandra , Soni Manisha , Kumar Vijay
Published: October 2015

Arsenic is a toxic metalloid present ubiquitously on earth. Since the last decade, it has gained considerable attention due to its severe neurotoxic effects. Arsenic can cross the blood–brain barrier and accumulate in different regions of the brain suggesting its role in neurological diseases. Arsenic exposure has been associated with reactive oxygen species generation, which is supposed to be one of the mechanisms of arsenic‐induced oxidative stress. Mitochondria, being the major source of reactive oxygen species generation may present an important target of arsenic toxicity. It is speculated that the proper functioning of the brain depends largely on efficient mitochondrial functions. Multiple studies have reported evidence of brain mitochondrial impairment after arsenic exposure. In this review, we have evaluated the proposed mechanisms of arsenic‐induced mitochondrial oxidative stress and dysfunction. The understanding of molecular mechanism of mitochondrial dysfunction may be helpful to develop therapeutic strategies against arsenic‐induced neurotoxicity. The ameliorative measures undertaken in arsenic‐induced mitochondrial dysfunction have also been highlighted. Copyright © 2015 John Wiley & Sons, Ltd.
Bone regeneration in critical bone defects using three‐dimensionally printed β‐tricalcium phosphate/hydroxyapatite scaffolds is enhanced by coating scaffolds with either dipyridamole or BMP‐2
Authors: Ishack Stephanie , Mediero Aranzazu , Wilder Tuere , Ricci John L. , Cronstein Bruce N.
Published: October 2015

Bone defects resulting from trauma or infection need timely and effective treatments to restore damaged bone. Using specialized three‐dimensional (3D) printing technology we have created custom 3D scaffolds of hydroxyapatite (HA)/beta‐tri‐calcium phosphate (β‐TCP) to promote bone repair. To further enhance bone regeneration we have coated the scaffolds with dipyridamole, an agent that increases local adenosine levels by blocking cellular uptake of adenosine. Nearly 15% HA:85% β‐TCP scaffolds were designed using Robocad software, fabricated using a 3D Robocasting system, and sintered at 1100°C for 4 h. Scaffolds were coated with BMP‐2 (200 ng mL−1), dypiridamole 100 µM or saline and implanted in C57B6 and adenosine A2A receptor knockout (A2AKO) mice with 3 mm cranial critical bone defects for 2–8 weeks. Dipyridamole release from scaffold was assayed spectrophotometrically. MicroCT and histological analysis were performed. Micro‐computed tomography (microCT) showed significant bone formation and remodeling in HA/β‐TCP‐dipyridamole and HA/β‐TCP‐BMP‐2 scaffolds when compared to scaffolds immersed in vehicle at 2, 4, and 8 weeks (n = 5 per group; p ≤ 0.05, p ≤ 0.05, and p ≤ 0.01, respectively). Histological analysis showed increased bone formation and a trend toward increased remodeling in HA/β‐TCP‐ dipyridamole and HA/β‐TCP‐BMP‐2 scaffolds. Coating scaffolds with dipyridamole did not enhance bone regeneration in A2AKO mice. In conclusion, scaffolds printed with HA/β‐TCP promote bone regeneration in critical bone defects and coating these scaffolds with agents that stimulate A2A receptors and growth factors can further enhance bone regeneration. These coated scaffolds may be very useful for treating critical bone defects due to trauma, infection or other causes. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 366–375, 2017.