bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photocatalysis
Authors: Herrmann Jean‐Marie 
Published: March 2017

Abstract

When photons are implicated in a catalytic reaction, the system becomes photocatalytic. The titania catalyst acts (1) by adsorbing the reactants and (2) by absorbing efficient photons which create electrons and holes, responsible for the subsequent redox reactions. Photocatalysis is a complex polyphasic system, involving simultaneously solid, gaseous and liquid phases plus the uv‐irradiation considered as the “electromagnetic” phase. The action of the five basic physico‐chemical parameters which control the kinetics are deeply described and demonstrated. In dry media, photocatalysis can be used as a means for selective mild oxidation reactions. In the presence of water, the generation of OH° radicals gives total oxidation reactions with a total mineralization in CO
2
+ H
2
O of pollutants, pesticides, dyes in water as well as total degradation of pollutants in (humid) air. Several examples are given. The actual tendency is the use of fixed beds of titania photocatalysts for air and water purification. Photocatalytic engineering is also developing with pilot plants, especially in the field of solar photocatalysis. Recent results are given about mechanisms, especially addressed to the radical nature of reaction intermediates.
Nanotubes
Authors: Vengatesan Muthukumaraswamy Ranagraj , Varghese Anish Mathai , Mittal Vikas 
Published: March 2017

AbstractNanotubes are one‐dimensional tubular nanomaterial having a great length to diameter ratio. The substantial research interest of nanotubes for miscellaneous applications is triggered from their unusual and superlative properties. This article narrates the different types of nanotubes and their synthesis and applications. The techniques used to modify various nanotubes properties and thus its performances for various applications are also discussed. Nanotubes have been incorporated with a number of inorganic and organic materials and then used in diverse applications such as sensors, biomedical, energy storage, environmental, and engineering. The presence of tubular structure, large aspect ratio and surface area, porous nature, chemical inertness, and enhanced mechanical and thermal properties are the highlights of nanotubes for vast acceptance in broad range of applications.
Skillful prediction of multidecadal variations in volcanic forcing
Authors: Tuel A. , Naveau P. , Ammann C. M. 
Published: March 2017

AbstractStratospheric sulfate injections from explosive volcanic eruptions are a primary natural climate forcing. Improved statistical models can now capture and simulate dynamical relationships in temporal variations of binary data. Leveraging these new techniques, the presented analysis clearly indicates that the number of large eruptions in the most recent records of explosive volcanism cannot be considered to be fully random. Including dynamical dependence in our models improves their ability to reproduce the historical record and thus forms a strong basis for skill in statistical prediction. Possible geophysical mechanisms behind the identified multidecadal variations are discussed, including variations in the observed length of day.
Identifying the evolution of Southern Hemisphere poleward moving auroral forms (PMAFs) in the context of plasma convection and magnetic reconnection
Authors: Tremsina E. A. , Mende S. B. , Frey H. U. 
Published: March 2017

AbstractIn this study we examine the dynamic evolution of Southern Hemisphere auroral precipitation patterns, specifically poleward moving auroral forms (PMAFs). The spatial, structural, and temporal characteristics of these events have been linked to underlying magnetopause‐boundary layer flux transfer events which are responsible for the generation of these ionospheric transient forms. We present five case studies of Southern Hemisphere PMAFs using optical data for 630.0 nm and 427.8 nm wavelengths from the US Automatic Geophysical Observatory Network in Antarctica. Emphasis is put on the unique capabilities of two‐dimensional optical data when it comes to studying PMAFs in the context of pulsed magnetic reconnection. In a detailed examination of three PMAFs recorded in 2007, we have found that their motion closely follows the underlying plasma convection patterns as determined from backscatter radar data, which in turn are governed by the interplanetary magnetic field (IMF) configuration. Of particular interest are periods when the positive IMF By component causes an asymmetric convection pattern which is biased toward the dawn region. These cases are consistent with the expected antisymmetric nature of the northern and southern hemisphere convection. In addition, we present two “pseudo” PMAFs which are actually independent auroral arcs executing poleward motions and occurring when the IMF Bz was positive. Using two‐dimensional images instead of one‐dimensional keograms or meridian scanning photometer recordings, we were able to distinguish these arcs from PMAFs. The misidentification of these arcs as PMAFs would cause inconsistencies with the theories of cusp aurora dynamics and magnetic reconnection, and some previous studies may have included such non‐PMAF events.
Statistical analysis of the reflection of incident O+ pickup ions at Mars: MAVEN observations
Authors: Masunaga K. , Seki K. , Brain D. A. , Fang X. , Dong Y. , Jakosky B. M. , McFadden J. P. , Halekas J. S. , Connerney J. E. P. , Mitchell D. L. , Eparvier F. G. 
Published: March 2017

AbstractAnalyzing ~1.3 year data set of O+ ion velocity distribution functions obtained from the Suprathermal and Thermal Ion Composition instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, we statistically investigate reflections of incident O+ pickup ions (>10 keV) occurring below the Martian bow shock. To quantitatively evaluate importance of the reflection of incident O+ pickup ions, we estimate reflection ratios by calculating average inward and outward O+ ion fluxes above the Martian bow shock. Our result shows that an average reflection ratio is 14.1 ± 6.7%. We also investigate dependences of the reflection ratio on the solar wind, solar EUV flux, and southern hemispheric crustal magnetic field on Mars. We find that the reflection ratio strongly depends on the magnitude of the interplanetary magnetic field (IMF), solar wind dynamic pressure, and gyroradius of O+ pickup ions in the solar wind, rather than the solar EUV flux and the crustal magnetic field. We suggest that the reflection ratio is determined by the magnetic field both in the solar wind and below the bow shock that mainly controls gyroradius of incident O+ pickup ions in these regions. We also find that the reflection ratio increases to 38.9 ± 10.2% as these parameters become extreme conditions (i.e., IMF magnitude >6 nT). Since incident O+ pickup ions are known to be a major source of atmospheric sputtering escape from Mars, our result suggests that ion reflections may have a role to reduce the sputtering escape from Mars under the extreme solar wind condition.
First observation of presunset ionospheric F region bottom‐type scattering layer
Authors: Li Guozhu , Ning Baiqi , Abdu M. A. , Wan Weixing , Wang Chi , Yang Guotao , Liu Kangkang , Liu Libo , Yan Chunxiao 
Published: March 2017

AbstractThe bottom‐type irregularity scattering layer (BSL) that can appear in the ionospheric F region bottomside has been observed generally after sunset, serving as a possible telltale of equatorial spread F (ESF). Using simultaneous multibeam radar measurements over two low‐latitude stations, Sanya (18.3°N, 109.6°E; dip latitude 13°N) and Fuke (19.3°N, 109.1°E; dip latitude 14°N) in China, we report, for the first time, a thin BSL that initially occurred at presunset (~1720 LT), much earlier than the occurrence of BSL generated from the equatorial plasma shear vortex‐driven instability. The presunset BSL was situated around 225 km altitude and continued to exist until the appearance of ESF plumes after sunset (~1930 LT). Interestingly, the Doppler velocities of the presunset BSL echoes measured by the radar and the F layer virtual heights obtained from the collocated Digisonde measurements over Sanya both show oscillations with a period of about 1 h, suggesting a close link between the occurrences of the BSL and of F region plasma density large‐scale wave structure before sunset. These observations could imply an important role of gravity waves in the generation of the presunset F region bottom‐type irregularities.
The hidden dynamics of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region
Authors: Claudepierre S. G. , O'Brien T. P. , Fennell J. F. , Blake J. B. , Clemmons J. H. , Looper M. D. , Mazur J. E. , Roeder J. L. , Turner D. L. , Reeves G. D. , Spence H. E. 
Published: March 2017

AbstractWe present measurements of relativistic electrons (0.7–1.5 MeV) in the inner zone and slot region obtained by the Magnetic Electron and Ion Spectrometer (MagEIS) instrument on Van Allen Probes. The data presented are corrected for background contamination, which is primarily due to inner‐belt protons in these low‐L regions. We find that ∼1 MeV electrons were transported into the inner zone following the two largest geomagnetic storms of the Van Allen Probes era to date, the March and June 2015 events. As ∼1 MeV electrons were not observed in Van Allen Probes data in the inner zone prior to these two events, the injections created a new inner belt that persisted for at least 1.5 years. In contrast, we find that electrons injected into the slot region decay on much faster timescales, approximately tens of days. Furthermore, we find no evidence of >1.5 MeV electrons in the inner zone during the entire time interval considered (April 2013 through September 2016). The energies we examine thus span a transition range in the steeply falling inner zone electron spectrum, where modest intensities are observed at 0.7 MeV, and no electrons are observed at 1.5 MeV. To validate the results obtained from the background corrected flux measurements, we also present detailed pulse‐height spectra from individual MagEIS detectors. These measurements confirm our results and also reveal low‐intensity inner zone and slot region electrons that are not captured in the standard background corrected data product. Finally, we briefly discuss efforts to refine the upper limit of inner zone MeV electron flux obtained in earlier work.
A scheme for forecasting severe space weather
Authors: Balan N. , Ebihara Y. , Skoug R. , Shiokawa K. , Batista I. S. , Tulasi Ram S. , Omura Y. , Nakamura T. , Fok M.‐C. 
Published: March 2017

AbstractA scheme is suggested and tested for forecasting severe space weather (SvSW) using solar wind velocity (V) and the north‐south component (Bz) of the interplanetary magnetic field (IMF) measured using the ACE (Advanced Composition Explorer) satellite from 1998 to 2016. SvSW has caused all known electric power outages and telegraph system failures. Earlier SvSW events such as the Carrington event of 1859, Quebec event of 1989 and an event in 1958 are included with information from the literature. Dst storms are used as references to identify 89 major space weather events (DstMin ≤ −100 nT) in 1998–2016. The coincidence of high coronal mass ejection (CME) front (or CME shock) velocity ΔV (sudden increase in V over the background by over 275 km/s) and sufficiently large Bz southward at the time of the ΔV increase is associated with SvSW; and their product (ΔV × Bz) is found to exhibit a large negative spike at the speed increase. Such a product (ΔV × Bz) exceeding a threshold seems suitable for forecasting SvSW. However, the coincidence of high V (not containing ΔV) and large Bz southward does not correspond to SvSW, indicating the importance of the impulsive action of large Bz southward and high ΔV coming through when they coincide. The need for the coincidence is verified using the CRCM (Comprehensive Ring Current Model), which produces extreme Dst storms (<DstMP> < −250 nT) characterizing SvSW when there is coincidence.
Biospheric and anthropogenic contributors to atmospheric CO2 variability in a residential neighborhood of Phoenix, Arizona
Authors: Song Jiyun , Wang Zhi‐Hua , Wang Chenghao 
Published: March 2017

AbstractUrban environment contributes significantly to the global carbon cycle with complex governing mechanisms due to the combined biospheric and anthropogenic contributors. In this study, we analyzed the patterns of boundary layer CO2 flux and concentration for a residential neighborhood in Phoenix, Arizona by using the eddy covariance technique and a single column atmospheric model. Atmospheric stability, anthropogenic emission, and biogenic effect are found to be key determinants to atmospheric CO2 variability. In a diurnal cycle, two CO2 flux peaks coincide with morning and afternoon peak traffic hours, exemplifying the influence of traffic emissions. In the annual cycle, maximum CO2 concentration is found in winter, mainly due to additional emission from the combustion of natural gas combined with the effect of poor dispersion. On the other hand, the minimum CO2 concentration is found in the spring and is attributable to the strong convective mixing and active vegetation uptake. In addition, prominent hysteresis has been found between the atmospheric CO2 concentration and air temperature with a “plait‐shaped” pattern in the diurnal cycle and an “oval‐shaped” loop for the seasonal variability.
Infiltration of meteoric water in the South Tibetan Detachment (Mount Everest, Himalaya): When and why?
Authors: Gébelin Aude , Jessup Micah J. , Teyssier Christian , Cosca Michael A. , Law Richard D. , Brunel Maurice , Mulch Andreas 
Published: March 2017

AbstractThe South Tibetan Detachment (STD) in the Himalayan orogen juxtaposes low‐grade Tethyan Himalayan sequence sedimentary rocks over high‐grade metamorphic rocks of the Himalayan crystalline core. We document infiltration of meteoric fluids into the STD footwall at ~17–15 Ma, when recrystallized hydrous minerals equilibrated with low‐δD (meteoric) water. Synkinematic biotite collected over 200 m of structural section in the STD mylonitic footwall (Rongbuk Valley, near Mount Everest) record high‐temperature isotopic exchange with D‐depleted water (δDwater = −150 ± 5‰) that infiltrated the ductile segment of the detachment most likely during mylonitic deformation, although later isotopic exchange cannot be definitively excluded. These minerals also reveal a uniform pattern of middle Miocene (15 Ma) 40Ar/39Ar plateau ages. The presence of low‐δD meteoric water in the STD mylonitic footwall is further supported by hornblende and chlorite with very low δD values of −183‰ and −162‰, respectively. The δD values in the STD footwall suggest that surface‐derived fluids were channeled down to the brittle‐ductile transition. Migration of fluids from the Earth's surface to the active mylonitic detachment footwall may have been achieved by fluid flow along steep normal faults that developed during synconvergent extension of the upper Tethyan Himalayan plate. High heat flow helped sustain buoyancy‐driven fluid convection over the timescale of detachment tectonics. Low δD values in synkinematic fluids are indicative of precipitation‐derived fluids sourced at high elevation and document that the ground surface above this section of the STD had already attained similar‐to‐modern topographic elevations in the middle Miocene.
Intraseasonal oscillation enhancing C5 typhoon occurrence over the tropical western North Pacific
Authors: Weng Chun‐Hsiung , Hsu Huang‐Hsiung 
Published: March 2017

AbstractThis study reveals that the atmosphere‐ocean coupled intraseasonal oscillation (ISO) enhances the occurrence frequency of Category 5 (C5) typhoons in the western North Pacific (WNP). Climatologically, the major region of C5 typhoon occurrence in the WNP is collocated with the intraseasonal variance of outgoing longwave radiation and tropical cyclone heat potential. The active convection and large ocean heat content associated with ISO create an environment conducive to the occurrence of C5 typhoons. Between 1980 and 2009, approximately 82% of C5 typhoons occurred when one or both of the two conditions were fulfilled. Our results suggest that compared with the thermodynamic factor of ocean heat content, dynamic factors (i.e., convection and near‐surface moisture convergence) within the favorable intraseasonal background state likely play a more influential role in inducing C5 typhoons.
Biocatalytic Approaches towards the Synthesis of Chiral Amino Alcohols from Lysine: Cascade Reactions Combining alpha‐Keto Acid Oxygenase Hydroxylation with Pyridoxal Phosphate‐ Dependent Decarboxylation
Authors: Baud Damien , Peruch Olivier , Saaidi Pierre‐Loïc , Fossey Aurélie , Mariage Aline , Petit Jean‐Louis , Salanoubat Marcel , Vergne‐Vaxelaire Carine , de Berardinis Véronique , Zaparucha Anne 
Published: March 2017

AbstractAmino alcohols are a very common structural motif in natural and synthetic molecules. Starting from l‐lysine and hydroxy‐l‐lysine, a straightforward biocatalytic synthesis of beta‐ and gamma‐amino alcohols is presented. Diastereoselective C–H oxidation catalyzed by an alpha‐keto acid‐dependent oxygenase followed by cleavage of the carboxylic acid moiety of the corresponding chiral hydroxy amino acid by a pyridoxal phosphate‐dependent decarboxylase enabled the formation of the target amino alcohols with moderate to complete conversions. Four beta‐ and gamma‐amino alcohols were obtained on a small scale in excellent yields and stereoselectivities.magnified image
A Moldable Nanocomposite Hydrogel Composed of a Mussel‐Inspired Polymer and a Nanosilicate as a Fit‐to‐Shape Tissue Sealant
Authors: Liu Yuan , Meng Hao , Qian Zichen , Fan Ni , Choi Wonyoung , Zhao Feng , Lee Bruce P. 
Published: March 2017

AbstractThe engineering of bioadhesives to bind and conform to the complex contour of tissue surfaces remains a challenge. We have developed a novel moldable nanocomposite hydrogel by combining dopamine‐modified poly(ethylene glycol) and the nanosilicate Laponite, without the use of cytotoxic oxidants. The hydrogel transitioned from a reversibly cross‐linked network formed by dopamine–Laponite interfacial interactions to a covalently cross‐linked network through the slow autoxidation and cross‐linking of catechol moieties. Initially, the hydrogel could be remolded to different shapes, could recover from large strain deformation, and could be injected through a syringe to adhere to the convex contour of a tissue surface. With time, the hydrogel solidified to adopt the new shape and sealed defects on the tissue. This fit‐to‐shape sealant has potential in sealing tissues with non‐flat geometries, such as a sutured anastomosis.
The Human Pelvis: Variation in Structure and Function During Gait
Authors: Lewis Cara L. , Laudicina Natalie M. , Khuu Anne , Loverro Kari L. 
Published: March 2017

ABSTRACTThe shift to habitual bipedalism 4–6 million years ago in the hominin lineage created a morphologically and functionally different human pelvis compared to our closest living relatives, the chimpanzees. Evolutionary changes to the shape of the pelvis were necessary for the transition to habitual bipedalism in humans. These changes in the bony anatomy resulted in an altered role of muscle function, influencing bipedal gait. Additionally, there are normal sex‐specific variations in the pelvis as well as abnormal variations in the acetabulum. During gait, the pelvis moves in the three planes to produce smooth and efficient motion. Subtle sex‐specific differences in these motions may facilitate economical gait despite differences in pelvic structure. The motions of the pelvis and hip may also be altered in the presence of abnormal acetabular structure, especially with acetabular dysplasia. Anat Rec, 300:633–642, 2017. © 2017 Wiley Periodicals, Inc.
Comprehensive assessment of sugarcane straw: implications for biomass and bioenergy production
Authors: Menandro Lauren Maine Santos , Cantarella Heitor , Franco Henrique Coutinho Junqueira , Kölln Oriel Tiago , Pimenta Maria Teresa Borges , Sanches Guilherme Martineli , Rabelo Sarita Cândida , Carvalho João Luís Nunes 
Published: March 2017

AbstractSugarcane straw, consisting of green tops and dry leaves, can be maintained on fields to improve soil quality, or harvested for bioenergy production. The optimum option between these two uses is still uncertain and requires further study. This study, conducted across three crop cycles, provides an assessment of the moisture, nutrients, ash, extractives, cellulose, hemicelluloses, and lignin contents of four sugarcane varieties across seven regions of south‐central Brazil. Suitability of the straw fractions for nutrient recycling, bioelectricity, and second‐generation ethanol production were also evaluated. Results showed that the sugarcane straw yield (dry mass) was 14.0 Mg ha−1, and the ratio of dry straw/fresh stalk was 12%. The composition of green tops and dry leaves differed consistently across varieties, sites, and crop cycles. Dry leaves represented 60% of the straw, but green tops contained about 70% of the total N, P, and K content. Therefore, green tops recycled up to four times more nutrients than dry leaves. Green tops also had six times higher moisture and greater chlorine content which decreased the mill process efficiency. In turn, dry leaves had higher lignin, cellulose, and hemicelluloses content, greater heating value (higher: 17.3 MJ kg−1; lower: 15.6 MJ kg−1) and tended to be a better second‐generation ethanol production feedstock. Overall, the results show that it is preferable to use dry leaves for bioenergy production while leaving green tops on the field for nutrient recycling. This study pointed out that more efficient methods for separating these fractions in the field need to be developed. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd
A cleavable self‐assembling tag strategy for preparing proteins and peptides with an authentic N‐terminus
Authors: Zhao Qing , Zhou Bihong , Gao Xianxing , Xing Lei , Wang Xu , Lin Zhanglin 
Published: March 2017

AbstractRecombinant protein expression and purification remains a central need for biotechnology. Herein, the authors report a streamlined protein and peptide purification strategy using short self‐assembling peptides and a C‐terminal cleavage intein. In this strategy, the fusion protein is first expressed as an aggregate induced by the self‐assembling peptide. Upon simple separation, the target protein or peptide with an authentic N‐terminus is then released in the solution by intein‐mediated cleavage. Different combinations of four self‐assembling peptides (ELK16, L6KD, FK and FR) with three inteins (Sce VMA, Mtu ΔI‐CM and Ssp DnaB) were explored. One protein and two peptides were used as model polypeptides to test the strategy. The intein Mtu ΔI‐CM, which has pH‐shift inducible cleavage, was found to work well with three self‐assembling peptides (L6KD, FR, FK). Using this intein gave a yield of protein or peptide comparable with that from other more established strategies, such as the Trx‐strategy, but in a simpler and more economical way. This strategy provides a simple and efficient method by which to prepare proteins and peptides with an authentic N‐terminus, which is especially effective for peptides of 30‐100 amino acids in length that are typically unstable and susceptible to degradation in Escherichia coli.