bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast Adjustments of the Asian Summer Monsoon to Anthropogenic Aerosols
Authors: Li Xiaoqiong , Ting Mingfang , Lee Dong Eun
Published: January 2018

Anthropogenic aerosols are a major factor contributing to human‐induced climate change, particularly over the densely populated Asian monsoon region. Understanding the physical processes controlling the aerosol‐induced changes in monsoon rainfall is essential for reducing the uncertainties in the future projections of the hydrological cycle. Here we use multiple coupled and atmospheric general circulation models to explore the physical mechanisms for the aerosol‐driven monsoon changes on different time scales. We show that anthropogenic aerosols induce an overall reduction in monsoon rainfall and circulation, which can be largely explained by the fast adjustments over land north of 20∘N. This fast response occurs before changes in sea surface temperature (SST), largely driven by aerosol‐cloud interactions. However, aerosol‐induced SST feedbacks (slow response) cause substantial changes in the monsoon meridional circulation over the oceanic regions. Both the land‐ocean asymmetry and meridional temperature gradient are key factors in determining the overall monsoon circulation response.
Four‐Spacecraft Magnetic Curvature and Vorticity Analyses on Kelvin‐Helmholtz Waves in MHD Simulations
Authors: Kieokaew Rungployphan , Foullon Claire , Lavraud Benoit
Published: January 2018

Four‐spacecraft missions are probing the Earth's magnetospheric environment with high potential for revealing spatial and temporal scales of a variety of in situ phenomena. The techniques allowed by these four spacecraft include the calculation of vorticity and the magnetic curvature analysis (MCA), both of which have been used in the study of various plasma structures. Motivated by curved magnetic field and vortical structures induced by Kelvin‐ Helmholtz (KH) waves, we investigate the robustness of the MCA and vorticity techniques when increasing (regular) tetrahedron sizes, to interpret real data. Here for the first time, we test both techniques on a 2.5‐D MHD simulation of KH waves at the magnetopause. We investigate, in particular, the curvature and flow vorticity across KH vortices and produce time series for static spacecraft in the boundary layers. The combined results of magnetic curvature and vorticity further help us to understand the development of KH waves. In particular, first, in the trailing edge, the magnetic curvature across the magnetopause points in opposite directions, in the wave propagation direction on the magnetosheath side and against it on the magnetospheric side. Second, the existence of a “turnover layer” in the magnetospheric side, defined by negative vorticity for the duskside magnetopause, which persists in the saturation phase, is reminiscent of roll‐up history. We found significant variations in the MCA measures depending on the size of the tetrahedron. This study lends support for cross‐scale observations to better understand the nature of curvature and its role in plasma phenomena.
Using Forbush Decreases to Derive the Transit Time of ICMEs Propagating from 1 AU to Mars
Authors: Freiherr von Forstner Johan L. , Guo Jingnan , Wimmer‐Schweingruber Robert F. , Hassler Donald M. , Temmer Manuela , Dumbović Mateja , Jian Lan K. , Appel Jan K. , Čalogović Jaša , Ehresmann Bent , Heber Bernd , Lohf Henning , Posner Arik , Steigies Christian T. , Vršnak Bojan , Zeitlin Cary J.
Published: January 2018

The propagation of 15 interplanetary coronal mass ejections (ICMEs) from Earth's orbit (1 AU) to Mars (∼1.5 AU) has been studied with their propagation speed estimated from both measurements and simulations. The enhancement of magnetic fields related to ICMEs and their shock fronts causes the so‐called Forbush decrease, which can be detected as a reduction of galactic cosmic rays measured on ground. We have used galactic cosmic ray (GCR) data from in situ measurements at Earth, from both STEREO A and STEREO B as well as GCR measurements by the Radiation Assessment Detector (RAD) instrument on board Mars Science Laboratory on the surface of Mars. A set of ICME events has been selected during the periods when Earth (or STEREO A or STEREO B) and Mars locations were nearly aligned on the same side of the Sun in the ecliptic plane (so‐called opposition phase). Such lineups allow us to estimate the ICMEs' transit times between 1 and 1.5 AU by estimating the delay time of the corresponding Forbush decreases measured at each location. We investigate the evolution of their propagation speeds before and after passing Earth's orbit and find that the deceleration of ICMEs due to their interaction with the ambient solar wind may continue beyond 1 AU. We also find a substantial variance of the speed evolution among different events revealing the dynamic and diverse nature of eruptive solar events. Furthermore, the results are compared to simulation data obtained from two CME propagation models, namely the Drag‐Based Model and ENLIL plus cone model.
Diagnosing the Role of Alfvén Waves in Magnetosphere‐Ionosphere Coupling: Swarm Observations of Large Amplitude Nonstationary Magnetic Perturbations During an Interval of Northward IMF
Authors: Pakhotin I. P. , Mann I. R. , Lysak R. L. , Knudsen D. J. , Gjerloev J. W. , Rae I. J. , Forsyth C. , Murphy K. R. , Miles D. M. , Ozeke L. G. , Balasis G.
Published: January 2018

High‐resolution multispacecraft Swarm data are used to examine magnetosphere‐ionosphere coupling during a period of northward interplanetary magnetic field (IMF) on 31 May 2014. The observations reveal a prevalence of unexpectedly large amplitude (>100 nT) and time‐varying magnetic perturbations during the polar passes, with especially large amplitude magnetic perturbations being associated with large‐scale downward field‐aligned currents. Differences between the magnetic field measurements sampled at 50 Hz from Swarm A and C, approximately 10 s apart along track, and the correspondence between the observed electric and magnetic fields at 16 samples per second, provide significant evidence for an important role for Alfvén waves in magnetosphere‐ionosphere coupling even during northward IMF conditions. Spectral comparison between the wave E‐ and B‐fields reveals a frequency‐dependent phase difference and amplitude ratio consistent with interference between incident and reflected Alfvén waves. At low frequencies, the E/B ratio is in phase with an amplitude determined by the Pedersen conductance. At higher frequencies, the amplitude and phase change as a function of frequency in good agreement with an ionospheric Alfvén resonator model including Pedersen conductance effects. Indeed, within this Alfvén wave incidence, reflection, and interference paradigm, even quasi‐static field‐aligned currents might be reasonably interpreted as very low frequency (ω → 0) Alfvén waves. Overall, our results not only indicate the importance of Alfvén waves for magnetosphere‐ionosphere coupling but also demonstrate a method for using Swarm data for the innovative experimental diagnosis of Pedersen conductance from low‐Earth orbit satellite measurements.
Evidence for Auroral Emissions From Callisto's Footprint in HST UV Images
Authors: Bhattacharyya Dolon , Clarke John T. , Montgomery Jordan , Bonfond Bertrand , Gérard Jean‐Claude , Grodent Denis
Published: January 2018

Auroral emissions are expected from the footprint of Callisto in Jupiter's upper atmosphere owing to the known interaction of its atmosphere with Jupiter's magnetosphere, and from the observed auroral emissions from the footprints of the other three Galilean satellites. The mapping of Callisto along modeled magnetic field lines at Jupiter, however, places the expected footprint at the same latitude as the main auroral emissions, making it difficult to detect. We analyzed ultraviolet images of Jupiter taken using the Hubble Space Telescope/Advanced Camera for Surveys instrument during a large observing campaign in 2007. Using a coaddition method similar to one used for Enceladus, we have identified a strong candidate for the footprint of Callisto on 24 May 2007. We tested this finding by applying the same coaddition technique to a nearly identical auroral configuration on 30 May 2007 when Callisto was behind Jupiter, not visible from Earth (central meridian longitude = 22°; sub‐Callisto system III longitude = 327°). By comparing the two coadded images, we can clearly see the presence of a strongly subcorotating spot close to the expected Callisto footprint location on 24 May and its absence on 30 May. On 24 May Callisto was located in the current sheet. We also found a probable candidate on 26 May 2007 during which time Callisto was positioned below the current sheet. The measured location and intensity of the auroral emission provide important information about the interaction of Callisto with Jupiter's magnetic field, the corotating plasma, and the neutral and ionized state of the thin atmosphere of Callisto.
Ion‐Scale Spectral Break in the Normal Plasma Beta Range in the Solar Wind Turbulence
Authors: Wang X. , Tu C.‐Y. , He J.‐S. , Wang L.‐H.
Published: January 2018

The spectral break (fb) of magnetic fluctuations at the ion scale in the solar wind is considered to give important clue on the turbulence dissipation mechanism. Among several possible mechanisms, the most notable two are related respectively to proton thermal gyroradius ρi and proton inertial length di. The corresponding frequencies of them are fρi=VSW/(2πρi) and fdi=VSW/(2πdi), respectively, where VSW is the solar wind speed. However, no definite conclusion has been given for which one is more reasonable because the two parameters have similar value when plasma beta β ∼ 1. Here we do a statistical study to see if the two ratios fb/fρi and fb/fdi have different dependence on β in the solar wind turbulence with 0.1 < β < 1.3. From magnetic measurements by the Wind spacecraft, we select 141 data sets with each one longer than 13 h. We find that the ratio fb/fdi is statistically not dependent on β, and the average value of it is 0.48 ± 0.06. However, fb/fρi increases with increasing β clearly and is significantly smaller than fb/fdi when β < 0.8. These new results show that fb is statistically 0.48fdi, and the influence of β could be negligible in the studied β range. It indicates a preference of the dissipation mechanism associated with di in the solar wind with 0.1 < β < 0.8. Further theoretical studies are needed to give detailed explanation.
The Complex Refractive Index of Volcanic Ash Aerosol Retrieved From Spectral Mass Extinction
Authors: Reed Benjamin E. , Peters Daniel M. , McPheat Robert , Grainger R. G.
Published: January 2018

The complex refractive indices of eight volcanic ash samples, chosen to have a representative range of SiO2 contents, were retrieved from simultaneous measurements of their spectral mass extinction coefficient and size distribution. The mass extinction coefficients, at 0.33–19 μm, were measured using two optical systems: a Fourier transform spectrometer in the infrared and two diffraction grating spectrometers covering visible and ultraviolet wavelengths. The particle size distribution was measured using a scanning mobility particle sizer and an optical particle counter; values for the effective radius of ash particles measured in this study varied from 0.574 to 1.16 μm. Verification retrievals on high‐purity silica aerosol demonstrated that the Rayleigh continuous distribution of ellipsoids (CDEs) scattering model significantly outperformed Mie theory in retrieving the complex refractive index, when compared to literature values. Assuming the silica particles provided a good analogue of volcanic ash, the CDE scattering model was applied to retrieve the complex refractive index of the eight ash samples. The Lorentz formulation of the complex refractive index was used within the retrievals as a convenient way to ensure consistency with the Kramers‐Kronig relation. The short‐wavelength limit of the electric susceptibility was constrained by using independently measured reference values of the complex refractive index of the ash samples at a visible wavelength. The retrieved values of the complex refractive indices of the ash samples showed considerable variation, highlighting the importance of using accurate refractive index data in ash cloud radiative transfer models.
Polar Ozone Response to Energetic Particle Precipitation Over Decadal Time Scales: The Role of Medium‐Energy Electrons
Authors: Andersson M. E. , Verronen P. T. , Marsh D. R. , Seppälä A. , Päivärinta S.‐M. , Rodger C. J. , Clilverd M. A. , Kalakoski N. , van de Kamp M.
Published: January 2018

One of the key challenges in polar middle atmosphere research is to quantify the total forcing by energetic particle precipitation (EPP) and assess the related response over solar cycle time scales. This is especially true for electrons having energies between about 30 keV and 1 MeV, so‐called medium‐energy electrons (MEE), where there has been a persistent lack of adequate description of MEE ionization in chemistry‐climate simulations. Here we use the Whole Atmosphere Community Climate Model (WACCM) and include EPP forcing by solar proton events, auroral electron precipitation, and a recently developed model of MEE precipitation. We contrast our results from three ensemble simulations (147 years) in total with those from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) in order to investigate the importance of a more complete description of EPP to the middle atmospheric ozone, odd hydrogen, and odd nitrogen over decadal time scales. Our results indicate average EPP‐induced polar ozone variability of 12–24% in the mesosphere, and 5–7% in the middle and upper stratosphere. This variability is in agreement with previously published observations. Analysis of the simulation results indicate the importance of inclusion of MEE in the total EPP forcing: In addition to the major impact on the mesosphere, MEE enhances the stratospheric ozone response by a factor of 2. In the Northern Hemisphere, where wintertime dynamical variability is larger than in the Southern Hemisphere, longer simulations are needed in order to reach more robust conclusions.
Ten Year Analysis of Tropopause‐Overshooting Convection Using GridRad Data
Authors: Cooney John W. , Bowman Kenneth P. , Homeyer Cameron R. , Fenske Tyler M.
Published: January 2018

Convection that penetrates the tropopause (overshooting convection) rapidly transports air from the lower troposphere to the lower stratosphere, potentially mixing air between the two layers. This exchange of air can have a substantial impact on the composition, radiation, and chemistry of the upper troposphere and lower stratosphere (UTLS). In order to improve our understanding of the role convection plays in the transport of trace gases across the tropopause, this study presents a 10 year analysis of overshooting convection for the eastern two thirds of the contiguous United States for March through August of 2004 to 2013 based on radar observations. Echo top altitudes are estimated at hourly intervals using high‐resolution, three‐dimensional, gridded, radar reflectivity fields created by merging observations from available radars in the National Oceanic and Atmospheric Administration Next Generation Weather Radar (NEXRAD) network. Overshooting convection is identified by comparing echo top altitudes with tropopause altitudes derived from the ERA‐Interim reanalysis. It is found that overshooting convection is most common in the central United States, with a weak secondary maximum along the southeast coast. The maximum number of overshooting events occur consistently between 2200 and 0200 UTC. Most overshooting events occur in May, June, and July when convection is deepest and the tropopause altitude is relatively low. Approximately 45% of the analyzed overshooting events (those with echo tops at least 1 km above the tropopause) have echo tops extending above the 380 K level into the stratospheric overworld.
Cocos (Keeling) Corals Reveal 200 Years of Multidecadal Modulation of Southeast Indian Ocean Hydrology by Indonesian Throughflow
Authors: Hennekam Rick , Zinke Jens , van Sebille Erik , ten Have Malou , Brummer Geert‐Jan A. , Reichart Gert‐Jan
Published: January 2018

The only low latitude pathway of heat and salt from the Pacific Ocean to the Indian Ocean, known as Indonesian Throughflow (ITF), has been suggested to modulate Global Mean Surface Temperature (GMST) warming through redistribution of surface Pacific Ocean heat. ITF observations are only available since ~1990s, and thus, its multidecadal variability on longer time scales has remained elusive. Here we present a 200 year bimonthly record of geochemical parameters (δ18O‐Sr/Ca) measured on Cocos (Keeling) corals tracking sea surface temperature (SST; Sr/Ca) and sea surface salinity (SSS; seawater‐δ18O═δ18Osw) in the southeastern tropical Indian Ocean (SETIO). Our results show that SETIO SSS and δ18Osw were impacted by ITF transport over the past 60 years, and therefore, reconstructions of Cocos δ18Osw hold information on past ITF variability on longer time spans. Over the past 200 years ITF leakage into SETIO is dominated by the interannual climate modes of the Pacific Ocean (El Niño—Southern Oscillation) and Indian Ocean (Indian Ocean Dipole). Pacific decadal climate variability (represented by the Pacific Decadal Oscillation) significantly impacted ITF strength over the past 200 years determining the spatiotemporal SST and SSS advection into the Indian Ocean on multidecadal time scales. A comparison of our SETIO δ18Osw record to GMST shows that ITF transport varied in synchrony with global warming rate, being predominantly high/low during GMST warming slowdown/acceleration, respectively. This hints toward an important role for the ITF in global warming rate modulation.
Miocene Oceanographic Evolution Based on the Sr and Nd Isotope Record of the Central Mediterranean
Authors: Cornacchia I. , Agostini S. , Brandano M.
Published: January 2018

The Miocene is a key interval in the geodynamic and oceanographic evolution of the Mediterranean marking the transition from a wide open basin to the modern closed basin. We used the Sr and Nd isotope records of two Miocene carbonate successions in the Adriatic to document that the evolution of the Mediterranean Basin controlled its seawater chemistry. During the late Aquitanian (~21 Ma), a time of glaciation and sea level lowstand, increased runoff affected the Sr isotope ratios of Mediterranean waters, whereas during the Burdigalian (20.44–15.97 Ma) volcanism in the circum‐Mediterranean area mainly influenced the Sr isotopic signature. During the Langhian (15.97–13.82 Ma), a time of sea level highstand associated with the Middle Miocene Climatic Optimum, the Nd isotope values indicate that waters exchanged between the Paratethys and the Central Mediterranean. The Central Mediterranean was well connected with the Atlantic Ocean between the Langhian and the early Tortonian (15.97–11.5 Ma), but exchange of water with the Paratethys declined. In the Messinian (6.3 Ma), connections between some marginal Mediterranean basins, for example, the proto‐Adriatic basin, and the Central Mediterranean, became restricted. In this basin, the Sr isotope values fell below the global reference line, while Nd isotope ratios show a strong affinity with the Atlantic Ocean and also indicate freshwater input. We conclude that the Mediterranean Nd isotope signature differs from that in the open oceans and reflects the basin physiography, reflecting a mix of signals derived from the adjacent oceans and local signals.
Grain Size Constraints on Glacial Circulation in the Southwest Atlantic
Authors: Spooner Peter T. , Thornalley David J. R. , Ellis Philip
Published: January 2018

Knowledge of past deep‐ocean current speeds has the potential to inform our understanding of changes in the climate system on glacial‐interglacial timescales, because they may be used to help constrain changes in deep‐ocean circulation rates and pathways. Of particular interest is the paleo‐flow speed of southern‐sourced deep water, which may have acted as a carbon store during the last glacial period. A location of importance in the northward transport of southern‐sourced bottom water is the Vema Channel, which divides the Argentine and Brazil basins in the South Atlantic. We revisit previous studies of paleo‐flow in Vema Channel using updated techniques in grain size analysis (i.e., mean sortable silt grain size), in Vema Channel cores and cores from the Brazil margin. Furthermore, we update the interpretation of the previous grain size studies in the light of many years further research into the glacial circulation of the deep Atlantic. Our results are broadly consistent with the existing data and suggest that during the last glacial period there was slightly more vigorous intermediate to middepth (shallower than 2,600 m) circulation in the South Atlantic Ocean than during the Holocene, whereas around 3,500 m the circulation was generally more sluggish. Increased glacial flow speed on the eastern side of the Vema Channel was likely related to an increase in northward velocity of AABW in the channel. An increase in Antarctic Bottom Water flow through the Vema Channel may have helped to sustain the large volume of southern‐sourced deep water in the Atlantic during the glacial period.
A Novel Long‐Time Accumulation Method for Double‐Satellite TDOA/FDOA Interference Localization
Authors: Wu Risheng , Zhang Yixiong , Huang Yanan , Xiong Jinyi , Deng Zhenmiao
Published: January 2018

In double‐satellite interference localization system, the position of the interference source is computed by estimating the time difference of arrival (TDOA) and the frequency difference of arrival (FDOA) between the signals retransmitted by two satellites. The traditional cross ambiguity function (CAF)‐based TDOA/FDOA estimation method requires the constant TDOA/FDOA between the two received signals, which can be satisfied only when the signal length is short. Therefore, the CAF estimation method cannot be applied in long‐time accumulation (LTA). To solve this problem, a novel LTA method is proposed based on signal segmentation. In the proposed method, the two received signals are first divided into several short signal segments. Subsequently, the TDOA, the initial FDOA, and the FDOA change rate of each signal segment are estimated by a modified CAF method. After compensating the FDOA difference between the signal segments, the results are spliced again to form a complete signal without FDOA variation. Consequently, the signal energy can be concentrated and the estimation accuracy of FDOA can be improved. Experimental results of real data demonstrate that greater signal‐to‐noise ratio (SNR) gain is achieved by the proposed method, compared to the traditional CAF‐based method.
ULBP1 is induced by hepatitis C virus infection and is the target of the NK cell‐mediated innate immune response in human hepatocytes
Authors: Dansako Hiromichi , Imai Hirotaka , Ueda Youki , Satoh Shinya , Wakita Takaji , Kato Nobuyuki
Published: January 2018

Natural killer (NK) cells through their NK group 2 member D (NKG2D) receptors recognize NKG2D ligands such as UL16‐binding proteins (ULBPs) on virus‐infected cells and subsequently trigger the host innate immune response. In the present study, we demonstrated that hepatitis C virus (HCV) induced the cell surface expression of ULBP1 in human immortalized hepatocyte PH5CH8 cells and human hepatoma HuH‐7 cell‐derived RSc cells. Interestingly, NK cell line NK‐92 induced cytotoxicity and interferon‐γ mRNA expression and subsequently reduced the levels of HCV RNA replication during co‐culture with HCV‐infected RSc cells. From these results, we conclude that ULBP1 is a target of the NK cell‐mediated innate immune response in HCV‐infected human hepatocytes.
Regucalcin confers resistance to amyloid‐β toxicity in neuronally differentiated PC12 cells
Authors: Murata Tomiyasu , Yamaguchi Masayoshi , Kohno Susumu , Takahashi Chiaki , Kakimoto Mitsumi , Sugimura Yukiko , Kamihara Mako , Hikita Kiyomi , Kaneda Norio
Published: January 2018

Amyloid‐β (Aβ), a primary component of amyloid plaques, has been widely associated with the pathogenesis of Alzheimer's disease. The Ca2+‐binding protein regucalcin (RGN) plays multiple roles in maintaining cell functions by regulating intracellular calcium homeostasis, various signaling pathways, and gene expression systems. Here, we investigated the functional role of RGN against Aβ‐induced cytotoxicity in neuronally differentiated PC12 cells. Overexpression of RGN reduced Aβ‐induced apoptosis by reducing mitochondrial dysfunction and caspase activation. It also attenuated Aβ‐induced reactive oxygen species production and oxidative damage and decreased Aβ‐induced nitric oxide (NO) overproduction, upregulation of inducible NO synthase by nuclear factor‐κB, and nitrosative damage. Interestingly, the genetic disruption of RGN increased the susceptibility of neuronally differentiated PC12 cells to Aβ toxicity. Thus, RGN possesses antioxidant activity against Aβ‐induced oxidative and nitrosative stress and may play protective roles against Aβ‐induced neurotoxicity in Alzheimer's disease.
Transparency in Structural Glass Systems Via Mechanical, Adhesive, and Laminated Connections ‐ Existing Research and Developments
Authors: Bedon Chiara , Santarsiero Manuel
Published: January 2018

The consistent architectural transparency demand in buildings is highly promoting the structural use of glass, in combination or to replace load‐bearing components made of traditional constructional materials. Despite its huge application in facades, roofs, envelopes, frame components, however, glass still represents a rather innovative and not well‐known material, requiring specific design conceptsm and further extended studies, toward the fulfillme nt of safe design requirements. A key role in glass systems and assemblies involving multiple components is given to connections. Major issues in their design, consequently, arise from restraining single glazing elements, as well as from ensuring their mechanical interaction with other constructional systems, as a part of full 3D buildings, including several materials, and various loading/boundary conditions. In this paper, an overview of typical connection types in use for glass systems is presented, with special consideration for mechanical, adhesive, and laminated adhesive connections, giving evidence of their typical applications, evolution, current design issues. Existing research and major projects are also discussed, both at the material/component level as well as at the assembly level.
Synthesis of Crystalline Black Phosphorus Thin Film on Sapphire
Authors: Li Cheng , Wu Ye , Deng Bingchen , Xie Yujun , Guo Qiushi , Yuan Shaofan , Chen Xiaolong , Bhuiyan Maruf , Wu Zishan , Watanabe Kenji , Taniguchi Takashi , Wang Hailiang , Cha Judy J. , Snure Michael , Fei Yingwei , Xia Fengnian
Published: January 2018

Black phosphorus (BP) has recently attracted significant attention due to its exceptional physical properties. Currently, high‐quality few‐layer and thin‐film BP are produced primarily by mechanical exfoliation, limiting their potential in future applications. Here, the synthesis of highly crystalline thin‐film BP on 5 mm sapphire substrates by conversion from red to black phosphorus at 700 °C and 1.5 GPa is demonstrated. The synthesized ≈50 nm thick BP thin films are polycrystalline with a crystal domain size ranging from 40 to 70 µm long, as indicated by Raman mapping and infrared extinction spectroscopy. At room temperature, field‐effect mobility of the synthesized BP thin film is found to be around 160 cm2 V−1 s−1 along armchair direction and reaches up to about 200 cm2 V−1 s−1 at around 90 K. Moreover, red phosphorus (RP) covered by exfoliated hexagonal boron nitride (hBN) before conversion shows atomically sharp hBN/BP interface and perfectly layered BP after the conversion. This demonstration represents a critical step toward the future realization of large scale, high‐quality BP devices and circuits.
Stable Light‐Emitting Diodes Using Phase‐Pure Ruddlesden–Popper Layered Perovskites
Authors: Tsai Hsinhan , Nie Wanyi , Blancon Jean‐Christophe , Stoumpos Constantinos C. , Soe Chan Myae Myae , Yoo Jinkyoung , Crochet Jared , Tretiak Sergei , Even Jacky , Sadhanala Aditya , Azzellino Giovanni , Brenes Roberto , Ajayan Pulickel M. , Bulović Vladimir , Stranks Samuel D. , Friend Richard H. , Kanatzidis Mercouri G. , Mohite Aditya D.
Published: January 2018

State‐of‐the‐art light‐emitting diodes (LEDs) are made from high‐purity alloys of III–V semiconductors, but high fabrication cost has limited their widespread use for large area solid‐state lighting. Here, efficient and stable LEDs processed from solution with tunable color enabled by using phase‐pure 2D Ruddlesden–Popper (RP) halide perovskites with a formula (CH3(CH2)3NH3)2(CH3NH3)n−1PbnI3n+1 are reported. By using vertically oriented thin films that facilitate efficient charge injection and transport, efficient electroluminescence with a radiance of 35 W Sr−1 cm−2 at 744 nm with an ultralow turn‐on voltage of 1 V is obtained. Finally, operational stability tests suggest that phase purity is strongly correlated to stability. Phase‐pure 2D perovskites exhibit >14 h of stable operation at peak operating conditions with no droop at current densities of several Amperes cm−2 in comparison to mixtures of 2D/3D or 3D perovskites, which degrade within minutes.
Synthesis of 7‐Azaindole Amidated Derivatives: An Efficient Usage of Acyl Azides as the Nitrogen Source
Authors: Li Wei‐Huan , Dong Lin
Published: January 2018

The dual behaviour of acyl azides in transition‐metal‐catalyzed direct C−H amidation is investigated. Variously substituted acyl azides reacted smoothly with 7‐azaindoles providing a diversity of C−C or C−N 7‐azaindole amidated derivatives. This amidation reaction shows an excellent controllability, which is believed to be dependent on catalyst system.

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Metal‐Free Azidation of α‐Hydroxy Esters and α‐Hydroxy Ketones Using Azidotrimethylsilane
Authors: Yin Xiao‐Ping , Zhu Lei , Zhou Jian
Published: January 2018

We herein report a commercially available perchloric acid catalyst capable of catalyzing the azidation of α‐hydroxy esters, α‐hydroxy ketones and taddols using azidotrimethylsilane in dichloromethane at room temperature. Various substituted tertiary alcohols are well tolerated in this reaction. Cα‐tetrasubstituted α‐amino acid derivatives were prepared by one‐pot sequential azidation and hydrogenation procedure. The advantage of this newly developed method includes operational simplicity, ready availability of catalyst, scale‐up ability, and also good functional group compatibility.

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Regioselective C‐7 Nitration of 8‐Aminoquinoline Amides Using tert‐Butyl Nitrite
Authors: Mondal Susmita , Samanta Sadhanendu , Hajra Alakananda
Published: January 2018

Regioselective C‐7 nitration of 8‐aminoquinoline amide has been achieved using tert‐butyl nitrite under metal‐free conditions at ambient temperature. The protocol is applicable to various aryl, heteroaryl as well as aliphatic carboxamides, and exhibits high functional group compatibility. The present method provides selective mononitrated quinoline derivatives. Experimental results suggest that the reaction likely proceeds through a radical pathway.

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Metal–Organic Framework‐Derived ZnO/ZnS Heteronanostructures for Efficient Visible‐Light‐Driven Photocatalytic Hydrogen Production
Authors: Zhao Xiuxia , Feng Jianrui , Liu Jingwei , Lu Jia , Shi Wei , Yang Guangming , Wang Guichang , Feng Pingyun , Cheng Peng
Published: January 2018

Developing highly active, recyclable, and inexpensive photocatalysts for hydrogen evolution reaction (HER) under visible light is significant for the direct conversion of solar energy into chemical fuels for various green energy applications. For such applications, it is very challenging but vitally important for a photocatalyst to simultaneously enhance the visible‐light absorption and suppress photogenerated electron–hole recombination, while also to maintain high stability and recyclability. Herein, a metal–organic framework (MOF)‐templated strategy has been developed to prepare heterostructured nanocatalysts with superior photocatalytic HER activity. Very uniquely, the synthesized photocatalytic materials can be recycled easily after use to restore the initial photocatalytic activity. It is shown that by controlling the calcination temperature and time with MOF‐5 as a host and guest thioacetamide as a sulfur source, the chemical compositions of the formed heterojunctions of ZnO/ZnS can be tuned to further enhance the visible‐light absorption and photocatalytic activity. The nanoscale heterojunction ZnO/ZnS structural feature serves to reduce the average free path of charge carriers and improve the charge separation efficiency, thus leading to significantly enhanced HER activity under visible‐light irradiation (λ > 420 nm) with high stability and recyclability without any cocatalyst.
Chemotherapeutic Drug Based Metal–Organic Particles for Microvesicle‐Mediated Deep Penetration and Programmable pH/NIR/Hypoxia Activated Cancer Photochemotherapy
Authors: Zhang Da , Wu Ming , Cai Zhixiong , Liao Naishun , Ke Kun , Liu Hongzhi , Li Ming , Liu Gang , Yang Huanghao , Liu Xiaolong , Liu Jingfeng
Published: January 2018

A novel metal–organic particle (MOP) based nanodrug formed by mild self‐assembly of chemotherapeutic drugs, including banoxantrone and doxorubicin, through Cu(II)‐mediated coordination effects, is reported. In this nanodrug, Cu(II) acts as a bridge to join AQ4N and DOX, and then, self‐assembly of [‐AQ4N‐Cu(II)‐(DOX)2‐Cu(II)‐]n complexes forms nanosized MOPs (referred to as ADMOPs) through multiple interactions including host–metal–guest coordination, hydrophobic interactions, π‐stacking, and van der Waals force. The ADMOPs reported here have several important features over conventional drugs, including tumor microenvironment pH‐sensitive drug release that can be tracked by “turning on” the fluorescence of AQ4N or DOX through proton competition with Cu(II) to break the coordination bonds and much deeper penetration into solid tumors via microvesicle‐mediated intercellular transfer. Most strikingly, the ADMOPs can serve as stimuli‐responsive nanocarriers to efficiently load the photosensitizer phthalocyanine due to their inherent highly porous characteristics. Thus, the ADMOPs significantly enhance the chemotherapeutic efficacy by “on‐demand” photodynamic therapy, which further induces a hypoxic environment that enhances the reduction of AQ4N to systematically increase the therapeutic efficiency. Taken together, the designed ADMOPs composed of chemotherapeutic drugs may serve as a potential programmable controlled synergistic agent for cancer therapy.
Smart Construction of Integrated CNTs/Li4Ti5O12 Core/Shell Arrays with Superior High‐Rate Performance for Application in Lithium‐Ion Batteries
Authors: Yao Zhujun , Xia Xinhui , Zhou Cheng‐ao , Zhong Yu , Wang Yadong , Deng Shengjue , Wang Weiqi , Wang Xiuli , Tu Jiangping
Published: January 2018

Exploring advanced high‐rate anodes is of great importance for the development of next‐generation high‐power lithium‐ion batteries (LIBs). Here, novel carbon nanotubes (CNTs)/Li4Ti5O12 (LTO) core/shell arrays on carbon cloth (CC) as integrated high‐quality anode are constructed via a facile combined chemical vapor deposition–atomic layer deposition (ALD) method. ALD‐synthesized LTO is strongly anchored on the CNTs' skeleton forming core/shell structures with diameters of 70–80 nm the combined advantages including highly conductive network, large surface area, and strong adhesion are obtained in the CC‐LTO@CNTs core/shell arrays. The electrochemical performance of the CC‐CNTs/LTO electrode is completely studied as the anode of LIBs and it shows noticeable high‐rate capability (a capacity of 169 mA h g−1 at 1 C and 112 mA h g−1 at 20 C), as well as a stable cycle life with a capacity retention of 86% after 5000 cycles at 10 C, which is much better than the CC‐LTO counterpart. Meanwhile, excellent cycling stability is also demonstrated for the full cell with LiFePO4 cathode and CC‐CNTs/LTO anode (87% capacity retention after 1500 cycles at 10 C). These positive features suggest their promising application in high‐power energy storage areas.
Enhanced Stability of Black Phosphorus Field‐Effect Transistors via Hydrogen Treatment
Authors: Wan Bensong , Zhou Qionghua , Zhang Junying , Wang Yue , Yang Bingchao , Lv Weiming , Zhang Baoshun , Zeng Zhongming , Chen Qian , Wang Jinlan , Wang Wenhong , Wen Fusheng , Xiang Jianyong , Xu Bo , Zhao Zhisheng , Tian Yongjun , Liu Zhongyuan
Published: January 2018

Atomically thin black phosphorus (BP) exhibits great potential for wide applications in future electronic and optoelectronic devices. However, BP exhibits fast ambient degradation and is thus severely limited in practical applications. Here, a simple strategy using hydrogen treatment to enhance the environmental stability of BP flakes is reported. Owing to the drastically suppressed ambient degradation by hydrogen treatment, atomic BP flakes are just slightly corroded on the surface even after up to 4 weeks in air, and more impressively, the BP field‐effect transistors still maintain over 85% of their initial mobility and ION/IOFF ratio. First‐principle calculations indicate that the hydrogen molecules are probably embedded between BP layers, and shift down the conduction band minimum, which strongly protects against the formation of superoxide on the surface and thus suppresses the ambient degradation of BP. This study provides a simple and nondestructive route to achieve air‐stable BP devices.
Heterogeneous Memristive Devices Enabled by Magnetic Tunnel Junction Nanopillars Surrounded by Resistive Silicon Switches
Authors: Zhang Yu , Lin Xiaoyang , Adam Jean‐Paul , Agnus Guillaume , Kang Wang , Cai Wenlong , Coudevylle Jean‐Rene , Isac Nathalie , Yang Jianlei , Yang Huaiwen , Cao Kaihua , Cui Hushan , Zhang Deming , Zhang Youguang , Zhao Chao , Zhao Weisheng , Ravelosona Dafine
Published: January 2018

Emerging nonvolatile memories (NVMs) have currently attracted great interest for their potential applications in advanced low‐power information storage and processing technologies. Conventional NVMs, such as magnetic random access memory and resistive random access memory, suffer from limitations of low tunnel magnetoresistance, low access speed, or finite endurance. NVMs with synergetic advantages are still highly desired for future computer architectures. This study reports a heterogeneous memristive device composed of a magnetic tunnel junction (MTJ) nanopillar surrounded by resistive silicon switches, named resistively enhanced MTJ (Re‐MTJ), which may be utilized for novel memristive memories, enabling new functionalities that are inaccessible for conventional NVMs. The Re‐MTJ device features a high ON/OFF ratio of >1000% and multilevel resistance behavior by combining magnetic switching together with resistive switching mechanisms. The magnetic switching originates from the MTJ, while the resistive switching is induced by a point‐switching filament process that is related to the mobile oxygen ions. Microscopic evidence of silicon aggregated as nanocrystals along the edges of the nanopillars verifies the synergetic mechanism of the heterogeneous memristive device. This device may provide new possibilities for advanced memristive memory and computing architectures, e.g., in‐memory computing and neuromorphics.
Kinetics of chitosan coagulation from aqueous solutions
Authors: Enache Alin Alexandru , David Laurent , Puaux Jean‐Pierre , Banu Ionut , Bozga Grigore
Published: January 2018

In this study, we investigated the kinetics of chitosan hydrogel formation from aqueous chitosan solutions with sodium hydroxide (NaOH) as the coagulant. Two sets of experiments were performed, one in a parallelepiped cell and the other with cylindrical chitosan solution extrudates. The coagulation occurred by the neutralization of the protonated amino groups (
) present in the chitosan chains, with the kinetics being controlled by NaOH transport toward the gelification zone. In this study, we confirmed the appropriateness of Fick's second law to describe NaOH transport, considering the instantaneous reaction between the NaOH and 
groups. The experimental data were used to determine the NaOH diffusion coefficient in gels having different chitosan concentrations. The diffusion coefficient values obtained from the cylindrical coagulation data were lower than those determined for linear coagulation because of the influences of transport geometry and gel structure, respectively. Accordingly, in fiber coagulation calculations, it is recommended to use diffusion coefficient values determined from cylindrical coagulation studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46062.
Event‐Triggered Fault Detection for Networked Control Systems Subject to Packet Dropout
Authors: Atitallah M. , Davoodi M. , Meskin N.
Published: January 2018

This paper investigates the problem of event‐triggered fault detection for discrete‐time networked systems subject to packet dropout. The main aim of the proposed approach is to efficiently use the communication network and reduce the signal transmission over the network. Toward this goal, a dynamic parity space event‐triggered fault detection approach is developed to generate a robust residual signal. Moreover, an adaptive threshold is utilized to overcome the limitations of static thresholds. The efficiency of proposed approach is experimentally demonstrated and validated for a laboratory three‐tank system.
Endogenous carbon monoxide production in extracorporeal membrane oxygenation‐related hemolysis: potential use of point‐of‐care CO‐oximetry carboxyhemoglobin to detect hemolysis
Authors: Kai Man Chan , Koon Ngai Lam
Published: January 2018

Key Clinical Message

Extracorporeal membrane oxygenation (ECMO)‐related hemolysis is a rare but devastating condition. Death is inevitable without early recognition and prompt management. Endogenous carbon monoxide production, as an epiphenomenon of hemolysis, potentially allows rapid detection of such condition by use of point‐of‐care CO‐oximetry carboxyhemoglobin.
Adsorption optimization of a biomass‐based fly ash for treating thermomechanical pulping (TMP) pressate using definitive screening design (DSD)
Authors: Cave Germaine , Fatehi Pedram
Published: January 2018

Wood chips are pretreated with steam or hot water prior to refining in a thermomechanical pulping (TMP) process. Currently, the resultant effluent (i.e., TMP pressate) must be treated in the wastewater treatment facility of the mill. Biomass fly ash is also generated in pulp mills as a residue from burning wood and other biomass in boilers. Fly ash utilization is currently limited and most of it is landfilled worldwide. In this study, biomass fly ash is used as an adsorbent for removing lignocelluloses from a TMP pressate. Biomass fly ash samples were fractionated, and the results showed that their carbon content decreased, but their metal content increased, as the particle size of the fly ash decreased. The main factors impacting the chemical oxygen demand (COD) and lignin concentration of a TMP pressate via treating with biomass fly ash samples (FA1 and FA2) were determined. Model equations and optimum conditions for these reductions were developed using definitive screening design (DSD). Generally, FA1 was considered a more effective adsorbent than FA2. The maximum COD removal from a TMP pressate (91.3 %) was achieved by using FA1 with a particle size of 0.43 mm at a dosage of 70 mg/g FA1/TMP pressate and a treatment time of 2 h. The maximum lignin removal from the TMP pressate (95 %) was obtained by using FA1 with a particle size of 0.11 mm at a dosage of 46.5 mg/g FA1/TMP pressate.
Fluorohectorite/LDPE nanocomposites: The role of organomodifiers and compatibilizer
Authors: Hu Lei , Pépin Keven , Bébin Philippe , Leclair Éric , Colas Fabienne , Vuillaume Pascal Y.
Published: January 2018

Organo‐fluorohectorites were either obtained commercially or synthesized by reacting unmodified fluorohectorite with ammonium salts. Modified and unmodified fluorohectorites were incorporated into low density polyethylene (LDPE) with or without maleic anhydride grafted polyethylene (MAPE) as a compatibilizer. Although clay aggregates were observed for all blends, the existence of an intercalated and exfoliated clay structure was confirmed according to morphological observations. Different types of cationic organomodifier were comparatively studied. It was found that alkyl chain length and amount of organomodifier were two factors influencing the dispersion state of fluorohectorites. Nanocomposites containing well‐dispersed fluorohectorites showed superior mechanical and barrier properties as compared to their counterparts. The presence of MAPE exhibited beneficial effects on the mechanical properties of the fluorohectorite/LDPE system, whereas the water vapour barrier property was adversely affected.
Synthesis of Large‐Pore ECNU‐19 Material (12 × 8‐R) via Interlayer‐Expansion of HUS‐2 Lamellar Silicate
Authors: Yang Boting , Jiang Jin‐Gang , Xu Hao , Wu Haihong , Wu Peng
Published: January 2018

A large‐pore ECNU‐19 material with unique pore system consisting of 12‐ring (12R) pore channels intersected by 8R channels was post‐synthesized via interlayer‐expansion of HUS‐2 lamellar silicate with silylating agent of 1,3‐dimethyltetramethoxydisiloxane (DMTMDS). In consideration of the fact that the HUS‐2 precursor possessed a special structure with a malposition of the neighboring layers as well as silicon vacancies on layer surface, a “detemplating disassembly – intercalation reassembly – silylation” strategy was proposed to realize a successful interlayer‐expansion and structural amending. An acid treatment was firstly performed to remove a part of the structure‐directing agent molecules, which favored the following intercalation by bulk organic species. The intercalation not only rearranged the relative position of up‐down layers but also provided enough interlayer space for the insertion of dimeric silane molecules. Two –OH groups attached to one silicon atom of the silane molecule reacted with two close silanols on the up‐surface layer, while the other two –OH groups condensed with two silanols on the down‐surface layer, which then connected the two layers via ‐Si‐O‐Si‐ pillars and constructed new 12R pores along a axis and 8R pores along c axis, respectively.
Metal‐Free I2‐Catalyzed Highly Selective Dehydrogenative Coupling of Alcohols and Cyclohexenones
Authors: Liang Yu‐Feng , Yuan Yizhi , Shen Tao , Song Song , Jiao Ning
Published: January 2018

The I2 catalyzed highly selective oxidative condensation of cyclohexenones and alcohols for the synthesis of aryl alkyl ethers has been described. DMSO is employed as the mild terminal oxidant. This novel methodology offers a metal‐free reaction condition, operational simplicity and broad substrate scope to afford valuable products from inexpensive reagents. Various meta‐substituted aromatic ethers which are hardly synthesized from the reported methods requiring meta‐substituted phenols, are efficiently prepared by the present protocol.
Bioisosteric Replacements Extracted from High‐Quality Structures in the Protein Databank
Authors: Seddon Matthew P. , Cosgrove David A. , Gillet Valerie J.
Published: January 2018

Bioisosterism is an important concept in the lead optimisation phase of drug discovery where the aim is to make modifications to parts of a molecule in order to improve some properties while maintaining others. We present an analysis of bioisosteric fragments extracted from the ligands in an established data set consisting of 121 protein targets. A pairwise analysis is carried out of all ligands for a given target. The ligands are fragmented using the BRICS fragmentation scheme and a pair of fragments is deemed to be bioisosteric if they occupy a similar volume of the protein binding site. We consider two levels of generality, one which does not consider the number of attachment points in the fragments and a more restricted case in which both fragments are required to have the same number of attachments. We investigate the extent to which the bioisosteric pairs that are found are common across different target.