bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of boundary layer mixing for the isotopic composition of surface vapor over the subtropical North Atlantic Ocean
Authors: Benetti Marion , Aloisi Giovanni , Reverdin Gilles , Risi Camille , Sèze Geneviève
Published: February 2015

During the summer 2012, we carried out continuous measurements of the isotopic composition (δ) of water vapor over the near‐surface subtropical North Atlantic Ocean (STRASSE cruise). In this region of excess evaporation, we investigate the control of evaporation and mixing with a lower troposphere‐derived, isotopically depleted air mass on the near‐surface δ. We use a simple model to simulate the near‐surface δ as the result of a two end‐member mixing of the evaporative flux with free tropospheric air. The evaporative flux δ was estimated by the Craig and Gordon equation while the δ of the lower troposphere was taken from the LMDZ‐iso global atmospheric circulation model. This simulation considers instantaneous mixing of lower tropospheric air with the evaporated flux and neglects lateral advection. Despite these simplifications, the simulations allow to identify the controls on the near‐surface δ. The d‐excess variability is largely a consequence of varying kinetic effects during evaporation, even during a convection event when the input of tropospheric vapor was strong. Kinetic effects and mixing processes affect simultaneously the near‐surface δ and result in the vapor occupying distinct domains in the δ18O‐δD space. The relative humidity‐d‐excess relationship shows that the closure assumption overestimates the d‐excess variability at short time scales (less than a day). We interpret this as due to an effect of the residence time of the near‐surface water vapor on the d‐excess. Finally, we highlight the importance of reproducing mixing processes in models simulating isotopes over the subtropical North Atlantic Ocean and propose an extension of the closure assumption for use in initial conditions of distillation calculations.
Forecasting surface wind speeds over offshore islands near Taiwan during tropical cyclones: Comparisons of data‐driven algorithms and parametric wind representations
Authors: Wei Chih‐Chiang
Published: February 2015

Tropical cyclones often affect the western North Pacific region. Between May and October annually, enormous flood damage is frequently caused by typhoons in Taiwan. This study adopted machine learning techniques to forecast the hourly wind speeds over offshore islands near Taiwan during tropical cyclones. To develop a highly reliable surface wind speed prediction technique, the four kernel‐based support vector machines for regression (SVR) models, comprising radial basis function, linear, polynomial, and Pearson VII universal kernels were used. To ensure the accuracy of the SVR model, traditional regressions and the parametric wind representations, comprising the modified Rankine profile, Holland wind profile, and DeMaria wind profile were used to compare wind speed forecasts. The methodology was applied to two islands near Taiwan, Lanyu, and Pengjia Islets. The forecasting horizon ranged from 1 to 6 h. The results indicated that the Pearson VII SVR is the most precise of the kernel‐based SVR models, regressions, and parametric wind representations. Additionally, Typhoons Nanmadol and Saola which made landfall over Taiwan during 2011 and 2012 were simulated and examined. The results showed that the Pearson VII SVR yielded more favorable results than did the regressions and Holland wind profile. In addition, we observed that Holland wind profile seems applicable to open ocean but unsuitable for areas affected by topographic effects, such as the Central Mountain Range of Taiwan.
Spectral observations of a natural bipolar cloud‐to‐ground lightning
Authors: Xue Simin , Yuan Ping , Cen Jianyong , Li Yajun , Wang Xuejuan
Published: February 2015

A natural bipolar cloud‐to‐ground lightning with two return strokes has been recorded with a slitless spectrograph. The subsequent positive stroke occurred retracing the preexisting channel created by the first negative stroke. They both were followed by a long continuing current going with M components. The spectra of the discharge channel for the M components were recorded first with a spectral range from 400 to 1000 nm. The spectral analysis suggests that the polarity of the discharge and the direction of the current have little effect on the structure of the spectrum, while the discharge strength, including current magnitude and duration, is the main factor determining the structure of the spectrum. The spectra of the negative and the positive return strokes are characterized by strong NII lines within the visible range, especially the two representative lines of 500.5 nm and 568.0 nm. The spectra of the M components were mainly from the contribution of OI and NI emissions in the infrared range, and typically, the four strong lines of OI 777.4 nm, NI 746.8, 821.6, and 868.0 nm were persistently observed in the spectra of the whole lightning process. In addition, the spectral characteristics in different channel sections show that background intensities for both the return strokes and all the M components have an increasing trend with increasing height along the channel. However, the intensities of NII lines for both the return strokes decrease slightly with increasing height along the channel, which should be related to the transmission characteristic of the current in the discharge channel.
Atomic‐scale simulation of space weathering in olivine and orthopyroxene
Authors: Quadery Abrar H. , Pacheco Shaun , Au Alan , Rizzacasa Natalie , Nichols Joshua , Le Timothy , Glasscock Cameron , Schelling Patrick K.
Published: February 2015

Classical molecular dynamics was used to study the annealing of anion and cation Frenkel defects in olivine and orthopyroxene minerals. While it was found that for both minerals, reorganization of the Si–O bonds, often accompanied by large Si displacements, occurs to maintain the fourfold coordination of the SiO4 tetrahedra, important differences are observed in their annealing behavior. Specifically, cation defects are substantially more mobile in olivine than in orthopyroxene leading to rapid annihilation of cation Frenkel defects and formation of extended defects in olivine. By contrast, the diffusion rate of anion defects in orthopyroxene is much higher than that in olivine and also exhibits large anisotropy. Consequently, it was found that diffusion in orthopyroxene occurs without significant annihilation of anion Frenkel defects or trapping of anion interstitials or vacancies into clusters. The results obtained here are discussed in the context of space weathering of olivine and orthopyroxene. Specifically, two important observations are made which may explain previous experimental results. First, ion irradiation experiments that show reduced tolerance for radiation damage in orthopyroxene may be explained by the rapid, one‐dimensional anion mobility which prevents healing of the lattice. Second, laser heating experiments which show that orthopyroxene has enhanced tolerance to reduction and the evolution of nanophase Fe inclusions could be due to the observed rapid anion diffusion in orthopyroxene, which might allow the bulk to act as a reservoir for the surface.
Disappearing Arctic tundra ponds: Fine‐scale analysis of surface hydrology in drained thaw lake basins over a 65 year period (1948–2013)
Authors: Andresen Christian G. , Lougheed Vanessa L.
Published: February 2015

Long‐term fine‐scale dynamics of surface hydrology in Arctic tundra ponds (less than 1 ha) are largely unknown; however, these small water bodies may contribute substantially to carbon fluxes, energy balance, and biodiversity in the Arctic system. Change in pond area and abundance across the upper Barrow Peninsula, Alaska, was assessed by comparing historic aerial imagery (1948) and modern submeter resolution satellite imagery (2002, 2008, and 2010). This was complemented by photogrammetric analysis of low‐altitude kite‐borne imagery in combination with field observations (2010–2013) of pond water and thaw depth transects in seven ponds of the International Biological Program historic research site. Over 2800 ponds in 22 drained thaw lake basins (DTLB) with different geological ages were analyzed. We observed a net decrease of 30.3% in area and 17.1% in number of ponds over the 62 year period. The inclusion of field observations of pond areas in 1972 from a historic research site confirms the linear downward trend in area. Pond area and number were dependent on the age of DTLB; however, changes through time were independent of DTLB age, with potential long‐term implications for the hypothesized geomorphologic landscape succession of the thaw lake cycle. These losses were coincident with increases in air temperature, active layer, and density and cover of aquatic emergent plants in ponds. Increased evaporation due to warmer and longer summers, permafrost degradation, and transpiration from encroaching aquatic emergent macrophytes are likely the factors contributing to the decline in surface area and number of ponds.
Complex terrain alters temperature and moisture limitations of forest soil respiration across a semiarid to subalpine gradient
Authors: Berryman E. M. , Barnard H. R. , Adams H. R. , Burns M. A. , Gallo E. , Brooks P. D.
Published: February 2015

Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. We quantified growing season soil respiration during both a drought year and a nondrought year across a complex landscape to identify how landscape and climate interact to control soil respiration. We asked the following questions: (1) How does soil respiration vary across the catchments due to terrain‐induced variability in moisture availability and temperature? (2) Does the relative importance of moisture versus temperature limitation of respiration vary across space and time? And (3) what terrain elements are important for dictating the pattern of soil respiration and its controls? Moisture superseded temperature in explaining watershed respiration patterns, with wetter yet cooler areas higher up and on north facing slopes yielding greater soil respiration than lower and south facing areas. Wetter subalpine forests had reduced moisture limitation in favor of greater seasonal temperature limitation, and the reverse was true for low‐elevation semiarid forests. Coincident climate poorly predicted soil respiration in the montane transition zone; however, antecedent precipitation from the prior 10 days provided additional explanatory power. A seasonal trend in respiration remained after accounting for microclimate effects, suggesting that local climate alone may not adequately predict seasonal variability in soil respiration in montane forests. Soil respiration climate controls were more strongly related to topography during the drought year highlighting the importance of landscape complexity in ecosystem response to drought.
Synchronization of dissolution and precipitation fronts during infiltration‐driven replacement in porous rocks
Authors: Kondratiuk Paweł , Tredak Hanna , Ladd Anthony J. C. , Szymczak Piotr
Published: February 2015

Coupled dissolution‐precipitation reactions, where two minerals share a common ion, occur frequently in geological replacement; the reactions are driven by an inflow of precipitating secondary ions and an outflow of dissolved primary ions. Although crystallization pressure is frequently invoked to explain volume‐preserving replacement, it cannot be operative if the chemical reactions lead to a loss of mineral volume; here the host rock that should confine the precipitating mineral is dissolving faster than the grains are growing. In this paper we propose two chemical mechanisms by which a rapid dissolution front and a slower precipitation front can be synchronized, and volume‐for‐volume replacement preserved. We analyze these mechanisms within the framework of reactive transport theory and show that morphological features observed in calcite replacement can be correlated with predictions of the models.
Evaluation of the inertial dissipation method within boundary layers using numerical simulations
Authors: Jabbari Aidin , Boegman Leon , Piomelli Ugo
Published: February 2015

We evaluated the accuracy of the inertial dissipation method to estimate the rate of dissipation of turbulent kinetic energy within boundary layers by performing well‐resolved numerical simulations of turbulent channel flows and comparing the dissipation calculated directly from the data, with that deduced from the frequency spectra. The convection velocity, commonly used to convert frequency spectra into wave number spectra is found to be larger than the local mean velocity by approximately a factor of 2 near the bed and about 10% in the logarithmic layer and beyond. Usage of the standard Kolmogorov constants (particularly in the vertical and spanwise directions) also leads to significant errors (50% or more) in computation of dissipation. Usage of the optimal Kolmogorov constants and the convection velocity, obtained from the simulation results could result in improved accuracy in dissipation calculation with the inertial method.
Coexisting structures from high‐ and low‐energy precipitation in fine‐scale aurora
Authors: Dahlgren H. , Lanchester B. S. , Ivchenko N.
Published: February 2015

High‐resolution multimonochromatic measurements of auroral emissions have revealed the first optical evidence of coexisting small‐scale auroral features resulting from separate high‐ and low‐energy populations of precipitating electrons on the same field line. The features exhibit completely separate motion and morphology. From emission ratios and ion chemistry modeling, the average energy and energy flux of the precipitation is estimated. The high‐energy precipitation is found to form large pulsating patches of 0.1 Hz with a 3 Hz modulation, and nonpulsating coexisting discrete auroral filaments. The low‐energy precipitation is observed simultaneously on the same field line as discrete filaments with no pulsation. The simultaneous structures do not interact, and they drift with different speeds in different directions. We suggest that the high‐ and low‐energy electron populations are accelerated by separate mechanisms, at different distances from Earth. The small‐scale structures could be caused by local instabilities above the ionosphere.
A numerical study of strike‐slip bend formation with application to the Salton Sea pull‐apart basin
Authors: Ye Jiyang , Liu Mian , Wang Hui
Published: February 2015

How stepovers of strike‐slip faults connect to form bends is a question important for understanding the formation of push‐up ranges (restraining bends) and pull‐apart basins (releasing bends). We investigated the basic mechanics of this process in a simple three‐dimensional viscoelastoplastic finite element model. Our model predicts localized plastic strain within stepovers that may eventually lead to the formation of strike‐slip bends. Major parameters controlling strain localization include the relative fault strength, geometry of the fault system, and the plasticity model assumed. Using the Drucker‐Prager plasticity model, in which the plastic yield strength of the crust depends on both shear and normal stresses, our results show that a releasing bend is easier to develop than a restraining bend under similar conditions. These results may help explain the formation of the Salton Sea pull‐apart basin in Southern California 0.5–0.1 Ma ago, when the stepover between the Imperial Fault and the San Andreas Fault was connected by the Brawley seismic zone.
The role of tropical Atlantic SST anomalies in modulating western North Pacific tropical cyclone genesis
Authors: Huo Liwei , Guo Pinwen , Hameed Saji N. , Jin Dachao
Published: February 2015

The connection between north tropical Atlantic (NTA) sea surface temperature (SST) anomalies and tropical cyclone (TC) genesis over the western North Pacific (WNP) and associated physical mechanisms are investigated in this study. We demonstrate a remarkable negative correlation of WNP TC genesis frequency with the (preceding) boreal spring NTA SST anomalies. Our analysis suggests that major factors for TC genesis including distributions of large‐scale vorticity and midtropospheric humidity are rendered unfavorable by remote teleconnections while barotropic energy conversion from the large‐scale flow is suppressed. As shown in recent studies, the remote teleconnection from the Atlantic is sustained and enhanced throughout the typhoon season through local air‐sea interactions. These results suggest that boreal spring NTA SST anomaly could be a new predictor for the seasonal WNP TC activity.
Decadal changes in Gulf of Alaska upwelling source waters
Authors: Pozo Buil Mercedes , Di Lorenzo Emanuele
Published: February 2015

Decadal changes in sea surface temperature (SST) in the Gulf of Alaska are linked to long‐term transitions in the marine ecosystem. While previous studies have identified the atmospheric variability of the Aleutian Low as an important driver of Ekman pumping and low‐frequency SST anomalies, the role of subsurface gyre‐scale dynamics remains unexplored. Using a set of reanalysis data sets from 1958 to the present, we find that subsurface temperature anomalies generated along the North Pacific Current significantly contribute through mean upwelling to decadal changes of SST in the Gulf of Alaska. This influence is comparable to the contribution associated with variations in atmospheric winds. Given the exceptional low‐frequency character of the propagation of subsurface anomalies (e.g., multidecadal) along the gyre, monitoring subsurface temperature anomalies up stream along the North Pacific Current may enhance the decadal predictability of SST in the Gulf of Alaska and its impact on local marine ecosystems.
Stoichiometry Variation in Materials with Three Mobile Carriers—Thermodynamics and Transport Kinetics Exemplified for Protons, Oxygen Vacancies, and Holes
Authors: Poetzsch D. , Merkle R. , Maier J.
Published: February 2015

Materials with three independent mobile charge carriers, in the sense of not being in local defect‐chemical equilibrium though naturally coupled through electroneutrality, are encountered in various cases of scientific and technological relevance. Examples are proton conducting perovskites under conditions at which hole and also oxygen vacancy conductivity may become significant, and mixed conducting cathode materials suited for fuel cells using proton conducting oxide electrolytes. Already the thermodynamics of the equilibrium situation is complex as a increase can lead to proton incorporation by water uptake (pure acid–base reaction) or by hydrogenation (redox reaction). As far as the even more complex transport kinetics are concerned, diffusion equations are derived which are exact for the interaction‐free (ideally dilute) situation. Kinetic implications are discussed and checked by exemplary numerical simulations. The treatment includes simple sub‐cases such as onefold relaxation on change, as well as complex patterns characterized by the appearance of more than one characteristic time scales (“twofold relaxation”) or apparent “moving boundary” kinetics. Implications for stability and functionality of ceramic materials are discussed.
Achieving a Significantly Increased Efficiency in Nondoped Pure Blue Fluorescent OLED: A Quasi‐Equivalent Hybridized Excited State
Authors: Zhang Shitong , Yao Liang , Peng Qiming , Li Weijun , Pan Yuyu , Xiao Ran , Gao Yu , Gu Cheng , Wang Zhiming , Lu Ping , Li Feng , Su Shijian , Yang Bing , Ma Yuguang
Published: February 2015

Excited state characters and components play a decisive role in photoluminescence (PL) and electroluminescence (EL) properties of organic light‐emitting materials (OLEDS). Charge‐transfer (CT) state is beneficial to enhance the singlet exciton utilizations in fluorescent OLEDs by an activated reverse intersystem crossing process, due to the minimized singlet and triplet energy splitting in CT excitons. However, the dominant CT component in the emissive state significantly reduces the PL efficiency in such materials. Here, the strategy is to carry out a fine excited state modulation, aiming to reach a golden combination of the high PL efficiency locally emissive (LE) component and the high exciton utilizing CT component in one excited state. As a result, a quasi‐equivalent hybridization of LE and CT components is obtained in the emissive state upon the addition of only an extra phenyl ring in the newly synthesized material 4‐[2‐(4′‐diphenylamino‐biphenyl‐4‐yl)‐phenanthro[9,10‐d]imidazol‐1‐yl]‐benzonitrile (TBPMCN), and the nondoped OLED of TBPMCN exhibited a record‐setting performance: a pure blue emission with a Commission Internationale de L'Eclairage coordinate of (0.16, 0.16), a high external quantum efficiency of 7.8%, and a high yield of singlet exciton of 97% without delayed fluorescence phenomenon. The excited state modulation could be a practical way to design low‐cost, high‐efficiency fluorescent OLED materials.
TPA Immobilization on Iron Oxide Nanocubes and Localized Magnetic Hyperthermia Accelerate Blood Clot Lysis
Authors: Voros Eszter , Cho Minjung , Ramirez Maricela , Palange Anna Lisa , De Rosa Enrica , Key Jaehong , Garami Zsolt , Lumsden Alan B. , Decuzzi Paolo
Published: February 2015

The low specificity and high risk of intracranial hemorrhage associated with currently approved thrombolytic therapies limit their efficacy in recanalizing occluded vessels. Here, a nanoscale thrombolytic agent is demonstrated by immobilizing tissue plasminogen activator molecules (tPA) over 20 nm clustered iron oxide nanocubes (NCs). The resulting nanoconstructs (tPA–NCs) are capable of dissolving clots via both direct interaction of tPA with the fibrin network (chemical lysis) and localized hyperthermia upon stimulation of superparamagnetic NCs with alternating magnetic fields (AMFs) (mechanical lysis). In vitro, as compared to free tPA, the proposed nanoconstructs demonstrate a ≈100‐fold increase in dissolution rate, possibly because of a more intimate interaction of tPA with the fibrin network. The clot dissolution rate is further enhanced (≈10‐fold) by mild, localized heating resulting from the exposure of tPA–NCs to AMF. Intravital microscopy experiments demonstrate blood vessel reperfusion within a few minutes post tail vein injection of tPA–NCs. The proposed nanoconstructs also exhibit high transverse relaxivity (>400 × 10–3 m−1 s−1) for magnetic resonance imaging. The multifunctional properties and the 3 orders of magnitude enhancement in clot dissolution make tPA–NCs a promising nano‐theranosis agent in thrombotic disease.
Engineering Gold Nanotubes with Controlled Length and Near‐Infrared Absorption for Theranostic Applications
Authors: Ye Sunjie , Marston Gemma , McLaughlan James R. , Sigle Daniel O. , Ingram Nicola , Freear Steven , Baumberg Jeremy J. , Bushby Richard J. , Markham Alexander F. , Critchley Kevin , Coletta Patricia Louise , Evans Stephen D.
Published: February 2015

Important aspects in engineering gold nanoparticles for theranostic applications include the control of size, optical properties, cytotoxicity, biodistribution, and clearance. In this study, gold nanotubes with controlled length and tunable absorption in the near‐infrared (NIR) region have been exploited for applications as photothermal conversion agents and in vivo photoacoustic imaging contrast agents. A length‐controlled synthesis has been developed to fabricate gold nanotubes (NTs) with well‐defined shape (i.e., inner void and open ends), high crystallinity, and tunable NIR surface plasmon resonance. A coating of poly(sodium 4‐styrenesulfonate) (PSS) endows the nanotubes with colloidal stability and low cytotoxicity. The PSS‐coated Au NTs have the following characteristics: i) cellular uptake by colorectal cancer cells and macrophage cells, ii) photothermal ablation of cancer cells using single wavelength pulse laser irradiation, iii) excellent in vivo photoacoustic signal generation capability and accumulation at the tumor site, iv) hepatobiliary clearance within 72 h postintravenous injection. These results demonstrate that these PSS‐coated Au NTs have the ideal attributes to develop their potential as effective and safe in vivo imaging nanoprobes, photothermal conversion agents, and drug delivery vehicles. To the best of knowledge, this is the first in vitro and in vivo study of gold nanotubes.
Photophysics of Organic–Inorganic Hybrid Lead Iodide Perovskite Single Crystals
Authors: Fang Hong‐Hua , Raissa Raissa , Abdu‐Aguye Mustapha , Adjokatse Sampson , Blake Graeme R. , Even Jacky , Loi Maria Antonietta
Published: February 2015

Hybrid organometal halide perovskites have been demonstrated to have outstanding performance as semiconductors for solar energy conversion. Further improvement of the efficiency and stability of these devices requires a deeper understanding of their intrinsic photophysical properties. Here, the structural and optical properties of high‐quality single crystals of CH3NH3PbI3 from room temperature to 5 K are investigated. X‐ray diffraction reveals an extremely sharp transition at 163 K from a twinned tetragonal I4/mcm phase to a low‐temperature phase characterized by complex twinning and possible frozen disorder. Above the transition temperature, the photoluminescence is in agreement with a band‐edge transition, explaining the outstanding performances of the solar cells. Whereas below the transition temperature, three different excitonic features arise, one of which is attributed to a free‐exciton and the other two to bound excitons (BEs). The BEs are characterized by a decay dynamics of about 5 μs and by a saturation phenomenon at high power excitation. The long lifetime and the saturation effect make us attribute these low temperature features to bound triplet excitons. This results in a description of the room temperature recombination as being due to spontaneous band‐to‐band radiative transitions, whereas a diffusion‐limited behavior is expected for the low‐temperature range.
Atomic‐Scale Structure Evolution in a Quasi‐Equilibrated Electrochemical Process of Electrode Materials for Rechargeable Batteries
Authors: Gu Lin , Xiao Dongdong , Hu Yong‐Sheng , Li Hong , Ikuhara Yuichi
Published: February 2015

Lithium‐ion batteries have proven to be extremely attractive candidates for applications in portable electronics, electric vehicles, and smart grid in terms of energy density, power density, and service life. Further performance optimization to satisfy ever‐increasing demands on energy storage of such applications is highly desired. In most of cases, the kinetics and stability of electrode materials are strongly correlated to the transport and storage behaviors of lithium ions in the lattice of the host. Therefore, information about structural evolution of electrode materials at an atomic scale is always helpful to explain the electrochemical performances of batteries at a macroscale. The annular‐bright‐field (ABF) imaging in aberration‐corrected scanning transmission electron microscopy (STEM) allows simultaneous imaging of light and heavy elements, providing an unprecedented opportunity to probe the nearly equilibrated local structure of electrode materials after electrochemical cycling at atomic resolution. Recent progress toward unraveling the atomic‐scale structure of selected electrode materials with different charge and/or discharge state to extend the current understanding of electrochemical reaction mechanism with the ABF and high angle annular dark field STEM imaging is presented here. Future research on the relationship between atomic‐level structure evolution and microscopic reaction mechanisms of electrode materials for rechargeable batteries is envisaged.
Giant Switchable Rashba Effect in Oxide Heterostructures
Authors: Zhong Zhicheng , Si Liang , Zhang Qinfang , Yin Wei‐Guo , Yunoki Seiji , Held Karsten
Published: February 2015

One of the most fundamental phenomena and a reminder of the electron's relativistic nature is the Rashba spin splitting for broken inversion symmetries in two‐dimensional condensed matter systems. Typically, this splitting is a tiny relativistic correction. By coupling ferroelectric BaTiO3 and a 5d (or 4d) transition metal oxide with a large spin‐orbit coupling, Ba(Os,Ir,Ru)O3, it is shown that giant Rashba spin splittings are indeed possible and even controllable by an external electric field. Based on density functional theory and a microscopic tight binding understanding, it is concluded that the electric field is amplified and stored as a ferroelectric Ti‐O distortion which, through the network of oxygen octahedra, induces a large (Os,Ir,Ru)‐O distortion. The BaTiO3/Ba(Os,Ru,Ir)O3 heterostructure is hence the ideal test station for switching and studying the Rashba effect and allows applications at room temperature.
In‐Situ Carbon Doping of TiO2 Nanotubes Via Anodization in Graphene Oxide Quantum Dot Containing Electrolyte and Carburization to TiOxCy Nanotubes
Authors: Favaro Marco , Leonardi Silvia , Valero‐Vidal Carlos , Nappini Silvia , Hanzlik Marianne , Agnoli Stefano , Kunze‐Liebhäuser Julia , Granozzi Gaetano
Published: February 2015

Anodic production of self‐organized titania nanotubes (TNTs) in an electrolyte enriched with graphene oxide quantum dots (GOQDs) is reported. The TNT‐GOQD composites grown under these conditions show in‐situ carbon doping, leading to the formation of anatase TiO2 domains and to the reduction to substoichiometric oxide (TiOx) and TiC. Surface science and electrochemical techniques are used in synergy to reveal that graphitic carbon is incorporated into TiO2 upon anodic nanotube growth promoting the formation of oxygen vacancies and thus TiO2 reduction. Upon annealing in ultrahigh vacuum, titanium oxycarbide (TiOxCy) is formed at temperatures ≥400 °C, where the material changes from a semiconductor to a semimetal. At the solid/liquid interface, the apparent electron donor density increases from as‐grown TNTs to as‐grown TNT‐GOQD composites due to the carbon doping, and the conductivity increases further with annealing temperature due to the increasing concentration of coordinatively unsaturated C atoms, crystallinity, and TiO2 reduction. The materials synthesized and characterized in this study find application in different areas ranging from visible light photocatalysis and photo‐electrochemistry to use as Li‐ion battery anodes and electrocatalyst supports, because it is possible to gradually tune the density of states below the Fermi level, which can be referred to as band‐gap engineering.
Making Ends Meet: Flow Synthesis as the Answer to Reproducible High‐Performance Conjugated Polymers on the Scale that Roll‐to‐Roll Processing Demands
Authors: Helgesen Martin , Carlé Jon E. , dos Reis Benatto Gisele A. , Søndergaard Roar R. , Jørgensen Mikkel , Bundgaard Eva , Krebs Frederik C.
Published: February 2015

Continuous flow methods are employed for the controlled polymerization of the roll‐to‐roll (R2R) compatible polymer PBDTTTz‐4 including optimization and upscaling experiments. The polymerization rate and materials’ quality can be increased significantly with the continuous flow method where reaction times down to 10 min afforded PBDTTTz‐4 with high molecular weight and a constant quality. The flow method enables full control of the molecular weight via tuning of the flow speed, catalyst loading, and temperature and avoids variation in materials’ quality associated with conventional batch synthesis. Upscaling from 300 mg batch synthesis to 10 g flow synthesis affords PBDTTTz‐4 with a production rate of up to 120 g day−1 for a very simple in‐house build flow reactor. An average power conversion efficiency (PCE) of 3.5% is achieved on a small scale (1 cm2) and an average PCE of 3.3% is achieved on a large scale (29 cm2). This shows that small device efficiencies can be scaled when using full R2R processing of flexible and encapsulated carbon‐based modules without the use of vacuum, indium‐tin‐oxide, or silver, with the best achieving a PCE of 3.8% PCE.
A Composite Gel–Polymer/Glass–Fiber Electrolyte for Sodium‐Ion Batteries
Authors: Gao Hongcai , Guo Bingkun , Song Jie , Park Kyusung , Goodenough John B.
Published: February 2015

An integrated preparation of a low‐cost composite gel–polymer/glass–fiber electrolyte with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) reinforced by a glass–fiber paper and modified by a polydopamine coating to tune the mechanical and surface properties of PVDF‐HFP is shown to be applicable to a sodium‐ion battery. The composite polymer matrix exhibits excellent mechanical strength and thermal stability up to 200 °C. After saturating with a liquid electrolyte, a wide electrochemical window and high ionic conductivity is obtained for the composite gel–polymer/glass–fiber electrolyte. When tested in a sodium‐ion battery with Na2MnFe(CN)6 as cathode, the rate capability, cycling performance, and coulombic efficiency are significantly improved. The results suggest that the composite polymer electrolyte is a very attractive separator for a large‐scale battery system where safety and cost are the main concerns.
Uncertainty quantification of property models: Methodology and its application to CO2‐loaded aqueous MEA solutions
Authors: Morgan Joshua C. , Bhattacharyya Debangsu , Tong Charles , Miller David C.
Published: February 2015

Uncertainties in property models can significantly affect the results obtained from process simulations. If these uncertainties are not quantified, optimal plant designs based on such models can be misleading. With this incentive, a systematic, generalized uncertainty quantification (UQ) methodology for property models is developed. Starting with prior beliefs about parametric uncertainties, a Bayesian method is used to derive informed posteriors using the experimental data. To reduce the computational expense, surrogate response surface models are developed. For downselecting the parameter space, a sensitivity matrix‐based approach is developed. The methodology is then deployed to the property models for an MEA‐CO2‐H2O system. The UQ analysis is found to provide interesting information about uncertainties in the parameter space. The sensitivity matrix approach is also found to be a valuable tool for reducing computational expense. Finally, the effect of the estimated parametric uncertainty on CO2 absorption and monoethanolamine (MEA) regeneration is analyzed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1822–1839, 2015
Significant relationship between the extent of pleural plaques and pulmonary asbestos body concentration in lung cancer patients with occupational asbestos exposure
Authors: Yusa Toshikazu , Hiroshima Kenzo , Sakai Fumikazu , Kishimoto Takumi , Ohnishi Kazuo , Usami Ikuji , Morikawa Tetsuyuki , Wu Di , Itoi Kazumi , Okamoto Kenzo , Shinohara Yasushi , Kohyama Norihiko , Morinaga Kenji
Published: February 2015

Background

The aim of this study was to elucidate whether there is a relationship between the extent of pleural plaques and pulmonary asbestos body concentration (PABC).

Methods

The subjects were 207 lung cancer patients with occupational asbestos exposure. We determined the plaque extent by findings on chest images using our own criteria. PABCs were measured in resected or autopsy lung specimens.

Results

There was a significant relationship between plaque extent and PABC. Seventy‐five percent of the patients determined to have extensive plaques based on our criteria had a PABC of ≥5,000 asbestos bodies per gram of dry lung tissue, which is one of the certification criteria of lung cancer caused by asbestos for workers' compensation in Japan.

Conclusions

In lung cancer patients, the plaque extent had a significant positive relationship with the PABC. The plaque extent would be useful as a proxy for PABC for lung cancer compensation purposes. Am. J. Ind. Med. 58:444–455, 2015. © 2015 Wiley Periodicals, Inc.
Development of a novel postnatal neurobehavioral scale for evaluation of common marmoset monkeys
Authors: Braun Katarina , Schultz‐Darken Nancy , Schneider Mary , Moore Colleen F. , Emborg Marina E.
Published: February 2015

Common marmoset (Callithrix jacchus) monkeys when compared to rhesus macaques (Macaca mullatta) present several advantages for disease modeling, especially transgenic initiatives, as they commonly give birth to twins, which increases sample size, have accelerated development and a shorter life span that facilitates the analysis of the onset of age‐related diseases. Yet, no tools are currently available to assess marmoset neurodevelopment during the initial first month of life. Here we report the creation of a novel Primate Postnatal Neurobehavioral Assessment Scale for marmoset monkeys (PPNAS‐M) that was based on currently available scales for human and rhesus monkeys. Twenty‐four healthy marmoset infants (12 females, 12 males) from 12 families were evaluated. The infant assessments involved 10‐minute testing administered at 15 and 30 days after birth. The PPNAS‐M consists of 41 noninvasive tests grouped into 5 testing categories: visual orienting, auditory and spatial orienting, motor responses, righting and body strength, and temperament tests. Testing at these two ages did not affect the overall health of the infants, suggesting that the PPNAS‐M is a non‐invasive testing tool. Significant maturation was demonstrated by increased scores in each of the five testing categories from postnatal day 15 to 30, with developmental patterns unique to marmosets. Principal component analysis defined 4 item groups (Orientation, State Control, Motor Maturity and Sensory Sensitivity) with 5 variables each. Orientation and State Control factors were highly similar to each other at both ages and correlated highly with previous item groupings used with rhesus macaques. Our results indicate that the PPNAS‐M is a useful assessment tool for detecting neuromotor, attention, and temperament status of infant marmosets and that it is sensitive to developmental effects. Further studies to validate the PPNAS‐M for the assessment of normal development versus early effects of developmental perturbations associated to prenatal exposures and transgenesis are warranted. Am. J. Primatol. 77:401–417, 2015. © 2015 Wiley Periodicals, Inc.
Body mass of wild bornean orangutans living in human‐dominated landscapes: Implications for understanding their ecology and conservation
Authors: Rayadin Yaya , Spehar Stephanie N.
Published: February 2015

Body mass is a key determinant of a species' ecology, including locomotion, foraging strategies, and energetics. Accurate information on the body mass of wild primates allows us to develop explanatory models for relationships among body size, ecology, and behavior and is crucial for reconstructing the ecology and behavior of fossil primates and hominins. Information on body mass can also provide indirect information on health and can be an important tool for conservation in the context of increasingly widespread habitat disturbance. This study reports body mass data recorded for wild Northeast Bornean orangutans (Pongo pygmaeus morio) during relocation efforts in forestry and oil palm plantations in East Kalimantan, Indonesia. The average mass of flanged adult males (n = 12, 74 ± 9.78 kg) and adult females (n = 7, 35.29 ± 7.32 kg) from this study were 13.6% and 9% lower, respectively, than the only other published wild Bornean orangutan body mass measurements, but the range of weights for both males and females was larger for this study. This pattern could be due to sampling error, data collection differences, or the influence of habitat disturbance, specifically a lack of access to resources, on individual health. When necessary relocations present the opportunity, we encourage researchers to prioritize the collection of body size data for the purposes of understanding ecology but also as an indirect means of monitoring population viability. As primate habitat becomes increasingly fragmented and altered by humans such data will become critical to our ability to make informed conservation decisions. Am J Phys Anthropol 157:339–346, 2015. © 2015 Wiley Periodicals, Inc.
Molekulare Erkennung in chemischen und biologischen Systemen
Authors: Persch Elke , Dumele Oliver , Diederich François
Published: February 2015

Strukturbasiertes Ligandendesign in der medizinischen Chemie und im Pflanzenschutz beruht auf der Identifizierung und Quantifizierung von schwachen, nichtkovalenten Wechselwirkungen und dem Verständnis der Rolle von Wasser. Ein wichtiges Werkzeug zum Abrufen von vorhandenem Wissen ist die Suche in Datenbanken von kleinen Molekülen und Proteinen. Die Erstellung eines thermodynamischen Profils zusammen mit der Röntgenstrukturanalyse und theoretischen Untersuchungen ist der Schlüssel zur Aufklärung des Energieprofils der Wasserverdrängung durch den Liganden. Biologische Bindungsstellen unterscheiden sich stark in ihrer Form, konformativen Dynamik und Polarität, weshalb verschiedene Entwicklungsstrategien für Liganden benötigt werden, wie hier anhand mehrerer Fallstudien gezeigt ist. Die Wechselwirkung zwischen Dipolen ist zu einem zentralen Baustein der molekularen Erkennung geworden. Orthogonale Wechselwirkungen, Halogenbrücken und Amid⋅⋅⋅π‐Stapelung bieten neue Möglichkeiten für innovative Leitstrukturoptimierung. Die Kombination von Untersuchungen an synthetischen Modellen und biologischen Rezeptoren ist notwendig, um verlässliche Informationen über schwache, nichtkovalente Wechselwirkungen und die Rolle von Wasser zu erlangen.
Biotechnologie von Morgen: metabolisch optimierte Zellen für die bio‐basierte Produktion von Chemikalien und Treibstoffen, Materialien und Gesundheitsprodukten
Authors: Becker Judith , Wittmann Christoph
Published: February 2015

Seit der Etablierung fermentativer Produktionsprozesse haben sich insbesondere Corynebacterium glutamicum, Escherichia coli und Saccharomyces cerevisiae als bedeutende Produktionsorganismen in der industriellen Biotechnologie durchgesetzt. Angetrieben von einem neu aufkommenden Interesse an Nachhaltigkeit und an der Verwendung nachwachsender Rohstoffe, wurden diese Mikroorganismen in den letzten Jahren zunehmend zu maßgeschneiderten Produktionsstämmen weiterentwickelt, wobei die Vielfalt und Komplexität ihrer natürlichen Syntheseleistung zugleich ein Gewinn und eine Herausforderung ist. Eine zielgerichtete Nutzbarmachung des großen metabolischen Potentials durch den synergistischen Einsatz des Systems Metabolic Engineering und der chemischen Synthese verspricht neue und innovative Konzepte für eine zukünftige Bio‐Ökonomie.
Three Dimensionally Ordered Mesoporous Carbon as a Stable, High‐Performance Li–O2 Battery Cathode
Authors: Xie Jin , Yao Xiahui , Cheng Qingmei , Madden Ian P. , Dornath Paul , Chang Chun‐Chih , Fan Wei , Wang Dunwei
Published: February 2015

Enabled by the reversible conversion between Li2O2 and O2, Li–O2 batteries promise theoretical gravimetric capacities significantly greater than Li‐ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeOx using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well‐defined pore structures, providing a unique material to gain insight into processes key to the operations of Li–O2 batteries. When decorated with Pd nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000 mAh gcarbon−1 and cyclability of more than 68 cycles.
Heterogeneous Platinum‐Catalyzed CH Perfluoroalkylation of Arenes and Heteroarenes
Authors: He Lin , Natte Kishore , Rabeah Jabor , Taeschler Christoph , Neumann Helfried , Brückner Angelika , Beller Matthias
Published: February 2015

Fluorinated organic compounds are gaining increasing interest for life science applications. The replacement of hydrogen in arenes or heteroarenes by a perfluoroalkyl group has a profound influence on the physical and biological properties of such building blocks. Here, an operationally simple protocol for the direct CH perfluoroalkylation of (hetero)arenes with RfI or RfBr has been developed, using a robust supported platinum catalyst. The ready availability of the starting materials, the excellent substrate tolerance, and the reusability of the catalyst make this method attractive for the synthesis of a variety of perfluoroalkyl‐substituted aromatic compounds. Preliminary mechanistic studies revealed the formation of radicals to be crucial in the reaction system.
Maximum Spin Polarization in Chromium Dimer Cations as Demonstrated by X‐ray Magnetic Circular Dichroism Spectroscopy
Authors: Zamudio‐Bayer Vicente , Hirsch Konstantin , Langenberg Andreas , Niemeyer Markus , Vogel Marlene , Ławicki Arkadiusz , Terasaki Akira , Lau J. Tobias , von Issendorff Bernd
Published: February 2015

X‐ray magnetic circular dichroism spectroscopy has been used to characterize the electronic structure and magnetic moment of Cr2+. Our results indicate that the removal of a single electron from the 4sσg bonding orbital of Cr2 drastically changes the preferred coupling of the 3d electronic spins. While the neutral molecule has a zero‐spin ground state with a very short bond length, the molecular cation exhibits a ferromagnetically coupled ground state with the highest possible spin of S=11/2, and almost twice the bond length of the neutral molecule. This spin configuration can be interpreted as a result of indirect exchange coupling between the 3d electrons of the two atoms that is mediated by the single 4s electron through a strong intraatomic 3d‐4s exchange interaction. Our finding allows an estimate of the relative energies of two states that are often discussed as ground‐state candidates, the ferromagnetically coupled 12Σ and the low‐spin 2Σ state.
Preparation and characterization of graphene oxide reinforced PVA film with boric acid as crosslinker
Authors: Chen Jie , Li Yadong , Zhang Yin , Zhu Yangguang
Published: February 2015

PVA films were prepared through aqueous solution method, and boric acid (BA) as well as graphene oxide (GO) was added to improve the mechanical and thermal properties. It was found that 5 wt % BA could increase the tensile strength threefold (from 23.3 to 67.7 MPa), and the incorporation of 0.2 wt % GO would provide additional percentage growth of 30% (from 67.7 to 88.5 MPa). Moreover, an enhancement of thermal stability of PVA film was found when BA or GO filler was added. The reinforcement mechanisms of both BA and GO were investigated, and a competitive phenomenon that the addition of BA would influence the reinforcement effect of GO sheets was found. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42000.
Morphology, mechanical performance, and nanoindentation behavior of injection molded PC/ABS‐MWCNT nanocomposites
Authors: Wegrzyn Marcin , Sahuquillo Oscar , Benedito Adolfo , Gimenez Enrique
Published: February 2015

In this work, nanocomposites of polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) with various loads of multiwall carbon nanotubes (MWCNT) are investigated. Material is previously formed by masterbatch dilution approach and further processed by injection molding at various velocities. Microscopic characterization of nanocomposites morphology reveals stronger dependence of MWCNT dispersion on processing parameters at higher nanofiller load. Dispersion of carbon nanotubes at various distances from the injection gate is studied by Raman spectroscopy showing lower deviation at elevated injection velocity. Nanoindentation results that are in agreement with uniaxial tensile testing show a slight decrease of nanocomposites' mechanical performance at 3.0 wt % MWCNT in samples injected at reduced velocity. This is explained by the increase of agglomeration behavior at these conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42014.