bluuebunny/crossref_metadata_2025 huggingface dataset:
Coronal electron density distributions estimated from CMEs, DH type II radio bursts, and polarized brightness measurements
Authors: Lee Jae‐Ok , Moon Y.‐J. , Lee Jin‐Yi , Lee Kyoung‐Sun , Kim R.‐S.
Published: April 2016

We determine coronal electron density distributions (CEDDs) by analyzing decahectometric (DH) type II observations under two assumptions. DH type II bursts are generated by either (1) shocks at the leading edges of coronal mass ejections (CMEs) or (2) CME shock‐streamer interactions. Among 399 Wind/WAVES type II bursts (from 1997 to 2012) associated with SOHO/LASCO (Large Angle Spectroscopic COronagraph) CMEs, we select 11 limb events whose fundamental and second harmonic emission lanes are well identified. We determine the lowest frequencies of fundamental emission lanes and the heights of leading edges of their associated CMEs. We also determine the heights of CME shock‐streamer interaction regions. The CEDDs are estimated by minimizing the root‐mean‐square error between the heights from the CME leading edges (or CME shock‐streamer interaction regions) and DH type II bursts. We also estimate CEDDs of seven events using polarized brightness (pB) measurements. We find the following results. Under the first assumption, the average of estimated CEDDs from 3 to 20 Rs is about 5‐fold Saito's model (NSaito(r)). Under the second assumption, the average of estimated CEDDs from 3 to 10 Rs is 1.5‐fold NSaito(r). While the CEDDs obtained from pB measurements are significantly smaller than those based on the first assumption and CME flank regions without streamers, they are well consistent with those on the second assumption. Our results show that not only about 1‐fold NSaito(r) is a proper CEDD for analyzing DH type II bursts but also CME shock‐streamer interactions could be a plausible origin for generating DH type II bursts.
The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems
Authors: Tao Wei‐Kuo , Li Xiaowen
Published: April 2016

A high‐resolution, two‐dimensional cloud‐resolving model with spectral‐bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low‐level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity‐governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF‐temperature buoyancy forcing. The balance among these terms determines the intensity of convection.
Air parcel trajectory dispersion near the tropical tropopause
Authors: Bergman John W. , Jensen Eric J. , Pfister Leonhard , Bui Thaopaul V.
Published: April 2016

Dispersion of backward air parcel trajectories that are initially tightly grouped near the tropical tropopause is examined using three ensemble approaches: “RANWIND,” in which different ensemble members use identical resolved wind fluctuations but different realizations of stochastic, multifractal simulations of unresolved winds; “PERTLOC,” in which members use identical resolved wind fields but initial locations are perturbed 2° in latitude and longitude; and a multimodel ensemble (“MULTIMODEL”) that uses identical initial conditions but different resolved wind fields and/or trajectory formulations. Comparisons among the approaches distinguish, to some degree, physical dispersion from that due to data uncertainty and the impacts of unresolved wind fluctuations from those of resolved variability. Dispersion rates are robust properties of trajectories near the tropical tropopause. Horizontal dispersion rates are typically ~3°/d, which is large enough to spread parcels throughout the tropics within typical tropical tropopause layer transport times (30–60 days) and underscores the importance of averaging large collections of trajectories to obtain reliable parcel source and pathway distributions. Vertical dispersion rates away from convection are ~2–3 hPa/d. Dispersion is primarily carried out by the resolved flow, and the RANWIND approach provides a plausible representation of actual trajectory dispersion rates, while PERTLOC provides a reasonable and inexpensive alternative to RANWIND. In contrast, dispersion from the MULTIMODEL calculations is important because it reflects systematic differences in resolved wind fields from different reanalysis data sets.
Sprite produced by consecutive impulse charge transfers following a negative stroke: Observation and simulation
Authors: Lu Gaopeng , Cummer Steven A. , Tian Ye , Zhang Hongbo , Lyu Fanchao , Wang Tao , Stanley Mark A. , Yang Jing , Lyons Walter A.
Published: April 2016

On the morning of 5 June 2013, two cameras of the SpriteCam network concurrently captured a red sprite with diffuse halo over a mesoscale convective system (MCS) passing the panhandle area of Oklahoma. This sprite was produced by a negative cloud‐to‐ground (CG) stroke with peak current of −103 kA in a manner different from previous observations in several aspects. First of all, the causative stroke of sprite is located by the National Lightning Detection Network (NLDN) in the trailing stratiform of MCS, instead of the deep convection typically for negative sprites. Second, the sprite‐producing stroke was likely the first stroke of a multistroke negative CG flash (with ≥6 CG strokes) whose evolution was mainly confined in the lower part of thunderstorm; although the parent flash of sprite might contain relatively long in‐cloud evolution prior to the first stroke, there is no evidence that the negative leader had propagated into the upper positive region of thundercloud as typically observed for the sprite‐producing/class negative CG strokes. Third, as shown by the simulation with a two‐dimensional full‐wave electrodynamic model, although the impulse charge moment change (−190 C km) produced by the main stroke was not sufficient to induce conventional breakdown in the mesosphere, a second impulse charge transfer occurred with ~2 ms delay to cause a substantial charge transfer (−290 C km) so that the overall charge moment change (−480 C km) exceeded the threshold for sprite production; this is a scenario different from the typical case discussed by Li et al. (2012). As for the source of the second current pulse that played a critical role to produce the sprite, it could be an M component whose charge source was at least 9 km horizontally displaced from the main stroke or a negative CG stroke (with weak peak current for the return stroke) that was not detected by the NLDN.
Intensification of aerosol pollution associated with its feedback with surface solar radiation and winds in Beijing
Authors: Yang Xin , Zhao Chuanfeng , Guo Jianping , Wang Yang
Published: April 2016

Beijing has been experiencing serious air pollution in recent years, resulting in serious impacts on the local environment and climate and on human health. In addition to individual pollution sources and weather systems, feedback between aerosols and downwelling solar radiation (DSR) and between aerosols and winds also contribute to heavy aerosol pollution. By using atmospheric visibility (VIS) to represent the relative amount of aerosol pollution during a 5 week observation around the Asia‐Pacific Economic Cooperation (APEC) period (22 October to 25 November 2014) over a site in south Beijing, China, we show clear positive relationships between DSR and VIS and between winds and VIS. The sensitivities of daily DSR and surface winds to VIS are approximately 15.42 W/m2/km and 0.068 m/s/km, respectively. The strengthening contributions to atmospheric visibility by surface DSR‐VIS interactions and between surface wind‐aerosol interactions are estimated at approximately 15% and 12%, respectively, in south Beijing around the APEC period.
Stratigraphy and formation of clays, sulfates, and hydrated silica within a depression in Coprates Catena, Mars
Authors: Weitz Catherine M. , Bishop Janice L.
Published: April 2016

We investigate the morphology, mineralogy, and stratigraphy of light‐toned layered deposits within a trough of Coprates Catena, centered at −15°N, 300°E. One of the deposits in the eastern portion of the trough contains numerous hydrated minerals, including Al‐phyllosilicates, Fe/Mg‐phyllosilicates, hydrated silica, hydrated sulfates, jarosite and acid alteration products characterized by a spectral doublet between 2.2 and 2.3 µm, and weakly hydrated materials. The Al‐phyllosilicates are observed both stratigraphically above and below the Fe/Mg‐phyllosilicate unit, which is a rare and perhaps unique association on Mars. Most of the western light‐toned layered deposit underlies a terraced fan. This deposit contains hydrated materials, including Al‐phyllosilicates and Fe/Mg‐phyllosilicates. Dip measurements indicate that both the eastern and western deposits dip toward the center of the trough, indicating that they postdate formation of the trough and are consequently Late Hesperian or younger in age. Volcanic ash, most likely erupted during formation of the pit crater in the eastern portion of the trough, seems to best explain our observations for several of the units. Valleys sourced from water along the plateau may have flowed into the trough and altered the sediments, with changing aqueous chemistries over time resulting in the diverse range of mineralogies now observed in the eastern light‐toned deposit. Our results reveal a complex sedimentary and aqueous history within the Coprates Catena trough, indicating that localized habitable conditions were possible relatively late in Martian history at a time when colder, drier conditions likely dominated the majority of the planet.
Reflection imaging of the Moon's interior using deep‐moonquake seismic interferometry
Authors: Nishitsuji Yohei , Rowe C. A. , Wapenaar Kees , Draganov Deyan
Published: April 2016

The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body‐wave seismic interferometry to deep moonquakes in order to retrieve zero‐offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep‐moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2–2.0 Hz).
Cyclic steps on ice
Authors: Yokokawa M. , Izumi N. , Naito K. , Parker G. , Yamada T. , Greve R.
Published: April 2016

Boundary waves often form at the interface between ice and fluid flowing adjacent to it, such as ripples under river ice covers, and steps on the bed of supraglacial meltwater channels. They may also be formed by wind, such as the megadunes on the Antarctic ice sheet. Spiral troughs on the polar ice caps of Mars have been interpreted to be cyclic steps formed by katabatic wind blowing over ice. Cyclic steps are relatives of upstream‐migrating antidunes. Cyclic step formation on ice is not only a mechanical but also a thermodynamic process. There have been very few studies on the formation of either cyclic steps or upstream‐migrating antidunes on ice. In this study, we performed flume experiments to reproduce cyclic steps on ice by flowing water, and found that trains of steps form when the Froude number is larger than unity. The features of those steps allow them to be identified as ice‐bed analogs of cyclic steps in alluvial and bedrock rivers. We performed a linear stability analysis and obtained a physical explanation of the formation of upstream‐migrating antidunes, i.e., precursors of cyclic steps. We compared the results of experiments with the predictions of the analysis and found the observed steps fall in the range where the analysis predicts interfacial instability. We also found that short antidune‐like undulations formed as a precursor to the appearance of well‐defined steps. This fact suggests that such antidune‐like undulations correspond to the instability predicted by the analysis and are precursors of cyclic steps.
Alongshore sediment bypassing as a control on river mouth morphodynamics
Authors: Nienhuis Jaap H. , Ashton Andrew D. , Nardin William , Fagherazzi Sergio , Giosan Liviu
Published: April 2016

River mouths, shoreline locations where fluvial and coastal sediments are partitioned via erosion, trapping, and redistribution, are responsible for the ultimate sedimentary architecture of deltas and, because of their dynamic nature, also pose great management and engineering challenges. To investigate the interaction between fluvial and littoral processes at wave‐dominated river mouths, we modeled their morphologic evolution using the coupled hydrodynamic and morphodynamic model Delft3D‐SWAN. Model experiments replicate alongshore migration of river mouths, river mouth spit development, and eventual spit breaching, suggesting that these are emergent phenomena that can develop even under constant fluvial and wave conditions. Furthermore, we find that sediment bypassing of a river mouth develops though feedbacks between waves and river mouth morphology, resulting in either continuous bypassing pathways or episodic bar bypassing pathways. Model results demonstrate that waves refracting into the river mouth bar create a zone of low alongshore sediment transport updrift of the river mouth, which reduces sediment bypassing. Sediment bypassing, in turn, controls the river mouth migration rate and the size of the river mouth spit. As a result, an intermediate amount of river discharge maximizes river mouth migration. The fraction of alongshore sediment bypassing can be predicted from the balance between the jet and the wave momentum flux. Quantitative comparisons show a match between our modeled predictions of river mouth bypassing and migration rates observed in natural settings.
Mars surface context cameras past, present, and future
Authors: Gunn M. D. , Cousins C. R.
Published: April 2016

Mars has been the focus of robotic space exploration since the 1960s, in which time there have been over 40 missions, some successful, some not. Camera systems have been a core component of all instrument payloads sent to the Martian surface, harnessing some combination of monochrome, color, multispectral, and stereo imagery. Together, these data sets provide the geological context to a mission, which over the decades has included the characterization and spatial mapping of geological units and associated stratigraphy, charting active surface processes such as dust devils and water ice sublimation, and imaging the robotic manipulation of samples via scoops (Viking), drills (Mars Science Laboratory (MSL) Curiosity), and grinders (Mars Exploration Rovers). Through the decades, science context imaging has remained an integral part of increasingly advanced analytical payloads, with continual advances in spatial and spectral resolution, radiometric and geometric calibration, and image analysis techniques. Mars context camera design has encompassed major technological shifts, from single photomultiplier tube detectors to megapixel charged‐couple devices, and from multichannel to Bayer filter color imaging. Here we review the technological capability and evolution of science context imaging instrumentation resulting from successful surface missions to Mars, and those currently in development for planned future missions.
Rapid variability of Antarctic Bottom Water transport into the Pacific Ocean inferred from GRACE
Authors: Mazloff Matthew R. , Boening Carmen
Published: April 2016

Air‐ice‐ocean interactions in the Antarctic lead to formation of the densest waters on Earth. These waters convect and spread to fill the global abyssal oceans. The heat and carbon storage capacity of these water masses, combined with their abyssal residence times that often exceed centuries, makes this circulation pathway the most efficient sequestering mechanism on Earth. Yet monitoring this pathway has proven challenging due to the nature of the formation processes and the depth of the circulation. The Gravity Recovery and Climate Experiment (GRACE) gravity mission is providing a time series of ocean mass redistribution and offers a transformative view of the abyssal circulation. Here we use the GRACE measurements to infer, for the first time, a 2003–2014 time series of Antarctic Bottom Water export into the South Pacific. We find this export highly variable, with a standard deviation of 1.87 sverdrup (Sv) and a decorrelation timescale of less than 1 month. A significant trend is undetectable.
Modeling magnetospheric energetic particle escape across Earth's magnetopause as observed by the MMS mission
Authors: Mauk Barry H. , Cohen Ian J. , Westlake Joseph H. , Anderson Brian J.
Published: April 2016

A longstanding puzzle is that the escape of magnetospheric energetic particles (greater than tens of keV) across Earth's magnetopause into the magnetosheath is common irrespective of conditions thought to engender magnetic reconnection and boundary normal magnetic fields. Multiple causes for escape have been invoked, including interactions with strong gradients, wave scattering, boundary dynamics, and boundary normal fields. Here we tackle only part of the problem by developing a relatively simple kinetic model including critical features not utilized in previous models. We find that particles can often completely escape without invoking waves or unmodeled magnetosheath structures for both northwardly and southwardly magnetosheath fields. Because multiple means of escape are found to be available, the particles are hard to completely contain, consistent with observations. The model also predicts specific pitch angle evolution signatures that uniquely identify boundary normal field‐enabled escape, now reported in a companion paper as observed by the Magnetospheric Multiscale (MMS) mission.
Will the Tibetan Plateau warming depend on elevation in the future?
Authors: Guo Donglin , Yu Entao , Wang Huijun
Published: April 2016

Elevation‐dependent warming, greater warming at higher elevations, tends to accelerate the ablation of solid water reserves on the Tibetan Plateau and is thus expected to affect the sustainable water supply of the plateau. In the context of a global climate that is predicted to continue to warm, whether elevation‐dependent warming exists on the Tibetan Plateau in the future and, if so, what its characteristics and mechanisms are, are important issues that have not yet been fully assessed. Using six sets of high‐resolution outputs from dynamical downscaling simulations based on regional climate models, we investigated the future situation regarding the elevation dependency of climate warming on the Tibetan Plateau. The simulated air temperature trends from the six simulations are validated using meteorological station observations. The trends from only two simulations are selected for analysis due to their statistically significant correlation with the observations. The warming rate first increases to a peak and then slightly declines along with elevation increasing from 2000 m to 5600 m. The peak of the warming rate is reached at variable elevations (4400–5200 m), which depends on the intensity of the warming. The elevation at which this peak occurs increases when the warming intensifies. Such elevation‐dependent warming is mostly caused by the decrease in upward short‐wave radiation due to the depletion of snow based on surface energy budget analysis. These results provide some understanding of the future elevation‐dependent warming on the Tibetan Plateau, which will be useful for evaluating the sustainability of water resources of the Tibetan Plateau water‐affected area.
Prognostic significance of lymphocyte‐to‐monocyte ratio in diffuse large B‐cell lymphoma: a systematic review and meta‐analysis
Authors: Xia Wen‐Kai , Lin Qing‐Feng , Shen Dong , Liu Zhi‐Li , Su Jun , Mao Wei‐Dong
Published: April 2016

Published evidence on the prognostic significance of lymphocyte‐to‐monocyte ratio (LMR) in diffuse large B‐cell lymphoma (DLBCL) is controversial. We performed an updated meta‐analysis from 12 reports with 5021 patients to more accurately evaluate the prognostic value of LMR in DLBCL. Herein, we confirmed that patients with low LMR had shorter overall survival and progression‐free survival than those with high LMR in DLBCL. Subgroup analyses indicated that patient source, cut‐off values of LMR, treatment methods, and sample size showed similar prognostic performance in DLBCL patients. No significant heterogeneity was observed for progression‐free survival (PFS, Phet = 0.192) among the enrolled studies. The meta‐analysis suggests that the LMR may be a potential biomarker in the prediction of clinical outcomes for DLBCL patients.
Patient‐Physician Discordance in Global Assessment in Rheumatoid Arthritis: A Systematic Literature Review With Meta‐Analysis
Authors: Desthieux Carole , Hermet Aurore , Granger Benjamin , Fautrel Bruno , Gossec Laure
Published: April 2016

Objective

The integration of the patient in therapeutic decision‐making is important in the management of rheumatoid arthritis (RA), but the patient opinion regarding disease status may differ from the physician's opinion. The aim of this study was to assess in the published literature the frequency and drivers of patient‐physician discordance in global assessment in RA.

Methods

A systematic literature review of all articles published up to January 2015 in Medline or Embase, reporting discordance in RA, was conducted by 2 investigators. Discordance was defined based on the absolute difference of patient global (PGA) and physician global assessments (PhGA) on 0–10‐cm scales. The frequency of discordance and its predictors were collected in each study. Frequencies of discordance were pooled by meta‐analysis using random effect.

Results

In all, 12 studies were selected (i.e., 11,879 patients): weighted mean ± SD age was 55.1 ± 13.9 years, weighted mean ± SD disease duration was 10.4 ± 9.3 years, and 80.7% were women. The value of the difference |PGA − PhGA| defining discordance varied between ≥0.5 cm (n = 2 studies) to ≥3 cm (n = 5 studies); the weighted mean value was 2.7 cm. The pooled percentage of patients with discordance was 43% (95% confidence interval 36%–51%; range 25%–76%). PGA was usually higher than PhGA. The drivers of PGA were pain and functional incapacity, whereas drivers of PhGA were joint counts and acute‐phase reactants.

Conclusion

Discordance in global assessment was most frequently defined as a difference of 3 points or more; even with such a stringent definition, up to half the patients were found to be discordant. The long‐term consequences of this discordance remain to be determined.
Mapping Perceptions of Lupus Medication Decision‐Making Facilitators: The Importance of Patient Context
Authors: Qu Haiyan , Shewchuk Richard M. , Alarcón Graciela , Fraenkel Liana , Leong Amye , Dall'Era Maria , Yazdany Jinoos , Singh Jasvinder A.
Published: April 2016

Objective

Numerous factors can impede or facilitate patients’ medication decision‐making and adherence to physicians’ recommendations. Little is known about how patients and physicians jointly view issues that affect the decision‐making process. Our objective was to derive an empirical framework of patient‐identified facilitators to lupus medication decision‐making from key stakeholders (including 15 physicians, 5 patients/patient advocates, and 8 medical professionals) using a patient‐centered cognitive mapping approach.

Methods

We used nominal group patient panels to identify facilitators to lupus treatment decision‐making. Stakeholders independently sorted the identified facilitators (n = 98) based on their similarities and rated the importance of each facilitator in patient decision‐making. Data were analyzed using multidimensional scaling and hierarchical cluster analysis.

Results

A cognitive map was derived that represents an empirical framework of facilitators for lupus treatment decisions from multiple stakeholders’ perspectives. The facilitator clusters were 1) hope for a normal/healthy life, 2) understand benefits and effectiveness of taking medications, 3) desire to minimize side effects, 4) medication‐related data, 5) medication effectiveness for “me,” 6) family focus, 7) confidence in physician, 8) medication research, 9) reassurance about medication, and 10) medication economics.

Conclusion

Consideration of how different stakeholders perceive the relative importance of lupus medication decision‐making clusters is an important step toward improving patient‐physician communication and effective shared decision‐making. The empirically derived framework of medication decision‐making facilitators can be used as a guide to develop a lupus decision aid that focuses on improving physician‐patient communication.
A New Criterion for Rupture Assessment of Rubber‐Like Materials under Mode‐I Crack Loading: The Effective Stretch Criterion
Authors: Ayatollahi Majid R. , Heydari‐Meybodi Mahdi , Dehghany Mohammad , Berto Filippo
Published: April 2016

A new criterion is presented for fracture assessment of rubber‐like materials weakened by a mode I crack. The criterion is based on two main assumptions: the existence of a damage zone around the crack tip and the dominant uniaxial nature of the stress field near the crack in rubber‐like materials. Considering these key features and employing the concepts of well‐known eight‐chain model, first, a failure criterion called the “Effective Stretch Criterion” has been proposed. Then, a procedure has been elaborated to calibrate the material parameters in the criterion. The criterion, finally, has been validated by using two sets of experimental data available in the literature.
Polymer Solar Cells Exceeding 10% Efficiency Enabled via a Facile Star‐Shaped Molecular Cathode Interlayer with Variable Counterions
Authors: Wang Zhenguo , Li Zuojia , Xu Xiaopeng , Li Ying , Li Kai , Peng Qiang
Published: April 2016

A series of star‐shaped small molecular cathode interlayer materials are synthesized for PTB7:PC71BM based polymer solar cells (PSCs), comprising neutral amino groups, quaternary ammonium ions, amino N‐oxides, and sulfobetaine ions as pendant polar functionalities, respectively. For the first time, the effect of these different pendant functional groups with or without mobile counterions on the cells' photovoltaic properties is investigated in detail. A large improvement in device performance is observed by inserting these cathode interfacial layers (CILs) between the PTB7:PC71BM active layer and the Al electrode. The CILs could effectively lower the work function of the Al cathode, increase the built‐in potential, and decrease the series resistance of the related PSCs. poly(9,9‐dioctylfluorene‐co‐N‐[4‐(3‐methyl‐propyl)]‐diphenylamine) with pendant quaternary ammonium ions shows the best cathode modification ability, giving rise to the highest power conversion efficiency of 10.1%, even better than that of the typical poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] based device. The design strategy and structure–property relationships concluded in this work will be helpful to develop more efficient cathode interface materials for high‐performance PSCs in the future.
Highly Conductive Optical Quality Solution‐Processed Films of 2D Titanium Carbide
Authors: Dillon Andrew D. , Ghidiu Michael J. , Krick Alex L. , Griggs Justin , May Steven J. , Gogotsi Yury , Barsoum Michel W. , Fafarman Aaron T.
Published: April 2016

MXenes comprise a new class of solution‐dispersable, 2D nanomaterials formed from transition metal carbides and nitrides such as Ti3C2. Here, it is shown that 2D Ti3C2 can be assembled from aqueous solutions into optical quality, nanometer thin films that, at 6500 S cm−1, surpass the conductivity of other solution‐processed 2D materials, while simultaneously transmitting >97% of visible light per‐nanometer thickness. It is shown that this high conductivity is due to a metal‐like free‐electron density as well as a high degree of coplanar alignment of individual nanosheets achieved through spincasting. Consequently, the spincast films exhibit conductivity over a macroscopic scale that is comparable to the intrinsic conductivity of the constituent 2D sheets. Additionally, optical characterization over the ultraviolet‐to‐near‐infrared range reveals the onset of free‐electron plasma oscillations above 1130 nm. Ti3C2 is therefore a potential building block for plasmonic applications at near‐infrared wavelengths and constitutes the first example of a new class of solution‐processed, carbide‐based 2D optoelectronic materials.
Hierarchical NiCo2S4 Nanowire Arrays Supported on Ni Foam: An Efficient and Durable Bifunctional Electrocatalyst for Oxygen and Hydrogen Evolution Reactions
Authors: Sivanantham Arumugam , Ganesan Pandian , Shanmugam Sangaraju
Published: April 2016

A recent approach for solar‐to‐hydrogen generation has been water electrolysis using efficient, stable, and inexpensive bifunctional electrocatalysts within strong electrolytes. Herein, the direct growth of 1D NiCo2S4 nanowire (NW) arrays on a 3D Ni foam (NF) is described. This NiCo2S4 NW/NF array functions as an efficient bifunctional electrocatalyst for overall water splitting with excellent activity and stability. The 3D‐Ni foam facilitates the directional growth, exposing more active sites of the catalyst for electrochemical reactions at the electrode–electrolyte interface. The binder‐free, self‐made NiCo2S4 NW/NF electrode delivers a hydrogen production current density of 10 mA cm–2 at an overpotential of 260 mV for the oxygen evolution reaction and at 210 mV (versus a reversible hydrogen electrode) for the hydrogen evolution reaction in 1 m KOH. This highly active and stable bifunctional electrocatalyst enables the preparation of an alkaline water electrolyzer that could deliver 10 mA cm–2 under a cell voltage of 1.63 V. Because the nonprecious‐metal NiCo2S4 NW/NF foam‐based electrodes afford the vigorous and continuous evolution of both H2 and O2 at 1.68 V, generated using a solar panel, they appear to be promising water splitting devices for large‐scale solar‐to‐hydrogen generation.
Sustained Delivery Growth Factors with Polyethyleneimine‐Modified Nanoparticles Promote Embryonic Stem Cells Differentiation and Liver Regeneration
Authors: Wang Meiyan , Yang Xiaomei , Zhang Peng , Cai Lei , Yang Xibin , Chen Youwei , Jing Yuanya , Kong Jilie , Yang Xiaowei , Sun Fang‐Lin
Published: April 2016

Stem‐cell‐derived hepatocyte transplantation is considered as a potential method for the therapy of acute and chronic liver failure. However, the low efficiency of differentiation into mature and functional hepatocytes remains a major challenge for clinical applications. By using polyethyleneimine‐modified silica nanoparticles, this study develops a system for sustained delivery of growth factors, leading to induce hepatocyte‐like cells (iHeps) from mouse embryonic stem cells (mESCs) and improve the expression of endoderm and hepatocyte‐specific genes and proteins significantly, thus producing a higher population of functional hepatocytes in vitro. When transplanted into liver‐injured mice after four weeks, mESC‐derived definitive endoderm cells treated with this delivery system show higher integration efficiency into the host liver, differentiated into iHeps in vivo and significantly restored the injured liver. Therefore, these findings reveal the multiple advantages of functionalized nanoparticles to serve as efficient delivery platforms to promote stem cell differentiation in the regenerative medicine.
A review of the operating limits in slot die coating processes
Authors: Ding Xiaoyu , Liu Jianhua , Harris Tequila A. L.
Published: April 2016

Slot die coating is a pre‐metered process commonly used for producing thin and uniform films. It is an important film fabrication method for applications where precise coating is required. A major concern in slot die coating processes is how to determine the operating limits to set the appropriate range of operating parameters, including coating speed, flow rate, vacuum pressure, coating gap, liquid viscosity and surface tension, etc. Operating limits directly determine the effectiveness and efficiency of the process. In this article, the current state of academic research on operating limits in slot die coating processes is reviewed. Specifically, the theories, mechanisms, and empirical conclusions related to the limits on vacuum pressure, the low‐flow limit, the limit of wet thickness for zero‐vacuum‐pressure cases, the limit of dynamic wetting failure, and the limits of coating speed for a specific flow rate are reviewed. The article concludes with some recommendations for future work. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2508–2524, 2016
Mentoring Relationship Closures in Big Brothers Big Sisters Community Mentoring Programs: Patterns and Associated Risk Factors
Authors: DeWit David J. , DuBois David , Erdem Gizem , Larose Simon , Lipman Ellen L. , Spencer Renée
Published: April 2016

Previous research suggests that early mentoring relationship (MR) closures may have harmful consequences for the health and well‐being of youth participating in community‐based mentoring programs. However, knowledge of the factors that lead some MRs to close early has been slow to emerge. This study examined patterns and correlates of early versus on‐time MR closures among 569 youth participating in Big Brothers Big Sisters community mentoring programs. Thirty‐four percent of youth experienced an early MR closure prior to the end of the program's 12 month period of commitment. The probability of closure was highest at 12 months into the MR. Early closures were positively associated with youth gender (girls), behavioral difficulties, and match determination difficulties. Early and on‐time closures were associated with youth extrinsic motives for joining the program. Early MR closures were negatively associated with youth perceptions of parent emotional support, parent social support, high quality MR, weekly contact in MR, and parent support of the MR. Implications for programming are discussed.
Clinical presentation and management practice of systemic mastocytosis. A survey on 460 Italian patients
Authors: Pieri Lisa , Bonadonna Patrizia , Elena Chiara , Papayannidis Cristina , Grifoni Federica Irene , Rondoni Michela , Girlanda Stefania , Mauro Marina , Magliacane Diomira , Elli Elena Maria , Iorno Maria Loredana , Almerigogna Fabio , Scarfì Federica , Salerno Roberto , Fanelli Tiziana , Gesullo Francesca , Corbizi Fattori Giuditta , Bonifacio Massimiliano , Perbellini Omar , Artuso Anna , Soverini Simona , De Benedittis Caterina , Muratori Simona , Pravettoni Valerio , Cova Vittoria , Cortellini Gabriele , Ciceri Fabio , Cortelezzi Agostino , Martinelli Giovanni , Triggiani Massimo , Merante Serena , Vannucchi Alessandro Maria , Zanotti Roberta
Published: April 2016

Systemic mastocytosis is a rare heterogeneous myeloproliferative neoplasm characterized by abnormal proliferation and activation of mast cells. We describe a large multicentre series of 460 adult patients with systemic mastocytosis, with a diagnosis based on WHO 2008 criteria, in a “real‐life” setting of ten Italian centers with dedicated multidisciplinary programs. We included indolent forms with (n = 255) and without (n = 165) skin lesions, smouldering (n = 20), aggressive (n = 28), associated with other hematological diseases mastocytosis (n = 21) and mast cell leukemia (n = 1). This series was uniquely characterized by a substantial proportion of patients with low burden of neoplastic mast cells; notably, 38% of cases were diagnosed using only minor diagnostic criteria according to WHO 2008 classification, underlying the feasibility of early diagnosis where all diagnostic approaches are made available. This has particular clinical relevance for prevention of anaphylaxis manifestations, that were typically associated with indolent forms. In multivariate analysis, the most important features associated with shortened overall survival were disease subtype and age at diagnosis >60 years. Disease progression was correlated with mastocytosis subtype and thrombocytopenia. As many as 32% of patients with aggressive mastocytosis suffered from early evolution into acute leukemia. Overall, this study provides novel information about diagnostic approaches and current presentation of patients with SM and underlines the importance of networks and specialized centers to facilitate early diagnosis and prevent disease‐associated manifestations. Am. J. Hematol. 91:692–699, 2016. © 2016 Wiley Periodicals, Inc.
Chiral Recognition of Carboxylates—Receptors, Analytical Tools, and More
Authors: Ulatowski Filip , Jurczak Janusz
Published: April 2016

Most carboxylic acids, which are among the most common molecules in biological systems, are chiral. The enantiomers of these species are commonly distinguished in nature, but such recognition has proven quite difficult to reproduce by using artificial receptors. Better knowledge of the chiral recognition of carboxylates is therefore crucial for a full understanding of host–guest phenomena in nature, and also for the design of new analytical devices. In this Focus Review we summarize and discuss the methods employed to evaluate receptors, and present a variety of structural designs that have been utilized in chiral receptors. Some advanced functions of receptors in sensors and sensor arrays are also reviewed.
Copper‐Catalyzed Double Decarboxylative Coupling Reactions of Alkynyl Carboxylic Acid and Glyoxylic Acid: Synthesis of Propargyl Amines and Imidazopyridines
Authors: Choi Jinseop , Lim Jeongah , Irudayanathan Francis Mariaraj , Kim Han‐Sung , Park Jaerim , Yu Su Been , Jang Yuna , Raja Gabriel Charles Edwin , Nam Kye Chun , Kim Jimin , Lee Sunwoo
Published: April 2016

The reaction of alkynyl carboxylic acids, glyoxylic acid derivatives, and amines in the presence of a copper catalyst afforded the corresponding propargyl amines in good yields. The alkynyl carboxylic acid of this coupling reaction shows similar reactivity to that of a terminal alkyne, and the reactivity of the glyoxylic acid is almost identical to that of an aldehyde. When 2‐aminopyridine was employed as the amine source, imidazopyridine derivatives were formed in good yields.
Palladium‐Catalyzed Direct Amination of Allylic Alcohols in Aqueous Media
Authors: Du Zhengyin , Yan Yufei , Fu Ying , Wang Kehu
Published: April 2016

Palladium chloride‐catalyzed amination of allylic alcohols with aromatic amines in the presence of triphenylphosphine and trifluoroacetic acid in the aqueous phase gave a wide range of allylamines in good to excellent yields under mild conditions. This protocol has a wide substrate scope and broad functional group tolerance. It is an environmentally friendly and highly atom‐economical method for N‐allylamine synthesis. A plausible mechanism involving a (π‐allyl)palladium complex intermediate is proposed.
Practice patterns in endoscopic dacryocystorhinostomy: survey of the American Rhinologic Society
Authors: Chen Sonia , Le Christopher H. , Liang Jonathan
Published: April 2016

Background

The introduction of advanced endoscopic techniques has facilitated significant growth in endoscopic dacryocystorhinostomy (EnDCR). The purpose of this study is to evaluate clinical practice patterns of otolaryngologists performing EnDCR.

Methods

A 25‐item survey was electronically disseminated to the American Rhinologic Society (ARS) membership from November 17, 2014 to December 14, 2014. The target group encompassed 1157 ARS members.

Results

A total of 85 (7.3%) physicians completed the survey. EnDCR was performed by 87% of respondents. The annual average number of EnDCR cases ranged from 1 to 10 in 65% of respondents, 11 to 25 in 15%, 26 to 50 in 6%, and >50 in 1%. A total of 48% of respondents had some to a lot of DCR exposure during training, and 60% had completed a rhinology fellowship. Respondents frequently perform preoperative nasal endoscopy and computed tomography (CT) imaging, but very infrequently perform ophthalmologic workup. Lacrimal stents were used often or always in 80%, with 38% keeping stents in place for 6 to 8 weeks. The mucosal flap preservation technique was used often or always in 40%. Topical antimetabolites were used often or always in only 1%. Ophthalmology was present in most cases to perform lacrimal intubation. Postoperative antibiotics, topical ophthalmic steroids, and oral steroids were prescribed often or always in 62%, 47%, and 23%, respectively. Postoperative endoscopic debridement was performed often or always in 69%. A total of 81% of respondents followed DCR patients for >2 months, with 17% following these patients for >1 year.

Conclusion

There is widespread integration of EnDCR procedures into rhinologic clinical practice among respondents. EnDCR practice patterns demonstrate moderate variation. In conjunction with evidence‐based medicine, these trends can highlight areas of controversy and help advance patient care.
Lewis‐Säure‐unterstützte metallkatalysierte Kreuzkupplung: Alkylierung von Arylmethylethern unter C‐O‐Bindungsspaltung ohne β‐Hydrideliminierung
Authors: Liu Xiangqian , Hsiao Chien‐Chi , Kalvet Indrek , Leiendecker Matthias , Guo Lin , Schoenebeck Franziska , Rueping Magnus
Published: April 2016

Diverse Arylmethylether können durch Trialkylaluminiumverbindungen mittels einer Alkylierung unter C‐O‐Bindungsspaltung in wertvolle Produkte überführt werden, wobei die bislang limitierenden β‐Hydrideliminierungen vermieden werden. Basierend auf der Vielfalt natürlich vorhandener oder leicht zugänglicher Anisolderivate ermöglicht die neue Nickel‐katalysierte dealkoxylierende Alkylierung orthogonale Synthesestrategien, die zunächst die dirigierenden und/oder aktivierenden Eigenschaften von Methoxysubstituenten an aromatischen Systemen ausnutzen und diese anschließend durch eine Alkylkette ersetzen.
High‐Affinity Proton Donors Promote Proton‐Coupled Electron Transfer by Samarium Diiodide
Authors: Chciuk Tesia V. , Anderson William R. , Flowers Robert A.
Published: April 2016

The relationship between proton‐donor affinity for SmII ions and the reduction of two substrates (anthracene and benzyl chloride) was examined. A combination of spectroscopic, thermochemical, and kinetic studies show that only those proton donors that coordinate or chelate strongly to SmII promote anthracene reduction through a PCET process. These studies demonstrate that the combination of SmII ions and water does not provide a unique reagent system for formal hydrogen atom transfer to substrates.
An Iodine‐Vapor‐Induced Cyclization in a Crystalline Molecular Flask
Authors: Knichal Jane V. , Shepherd Helena J. , Wilson Chick C. , Raithby Paul R. , Gee William J. , Burrows Andrew D.
Published: April 2016

A vapor‐induced cyclization has been observed in the host environment of a crystalline molecular flask (CMF), within which 1,8‐bis(2‐phenylethynyl)naphthalene (bpen), a diarenynyl system primed for cyclization, was exposed to iodine vapor to yield the corresponding indeno[2,1‐α]phenalene species. The cyclization process, unique in its vapor‐induced, solvent‐free nature, was followed spectroscopically, and found to occur concurrently with the displacement of lattice solvent for molecular iodine in CMF⋅0.75 bpen⋅2.25 CHCl3⋅H2O. The cyclization occurred under mild conditions and without the need to suspend the crystals in solvent. The ability of CMFs to host purely gas‐induced reactions is further highlighted by the subsequent sequential oxidation reaction of cyclized 7‐iodo‐12‐phenylindeno[2,1‐α]phenalene (ipp) with molecular oxygen derived from air, yielding 12‐hydroxy‐7‐iodo‐2‐phenylindeno[2,1‐α]phenalen‐1(12H)‐one (hipp).
Lichtinduzierte Wasseroxidation durch ein molekulares Manganvanadiumoxid
Authors: Schwarz Benjamin , Forster Johannes , Goetz McKenna K. , Yücel Duygu , Berger Claudia , Jacob Timo , Streb Carsten
Published: April 2016

In der Natur findet die photosynthetische Wasseroxidation an einem anorganischen Calcium‐Mangan‐Oxo‐Komplex (Oxygen‐Evolving Complex, OEC) im Photosystem II statt. Hier berichten wir über ein synthetisches Modell des OEC auf Basis eines molekularen Manganvanadiumoxids: [Mn4V4O17(OAc)3]3−. Dessen Herzstück ist ein [Mn4O4]6+‐Kubus, der die homogene, lichtgetriebene Oxidation von Wasser zu Sauerstoff katalysiert. Der zentrale Kubus wird durch ein tripodales Polyoxovanadat, [V4O13]6−, sowie drei Acetatliganden stabilisiert. In Kombination mit der Lichtsammeleinheit [Ru(bpy)3]2+ und dem Elektronenakzeptor S2O82− erfolgt die lichtgetriebene Wasseroxidation mit Umsatzzahlen von ca. 1150 und Umsatzfrequenzen von ca. 1.75 s−1. Elektrochemische, massenspektrometrische sowie spektroskopische Untersuchungen geben einen Einblick in die Stabilität und Reaktivität des Manganvanadiumoxids. Dieses könnte als Modellsystem für die Struktur und Reaktivität des OEC sowie für heterogene Wasseroxidationskatalysatoren fungieren.
Plastic Antibodies for Cosmetics: Molecularly Imprinted Polymers Scavenge Precursors of Malodors
Authors: Nestora Sofia , Merlier Franck , Beyazit Selim , Prost Elise , Duma Luminita , Baril Bérangère , Greaves Andrew , Haupt Karsten , Tse Sum Bui Bernadette
Published: April 2016

Molecularly imprinted polymers (MIPs) are synthetic antibody mimics capable of specific molecular recognition. Advantageously, they are more stable, easy to tailor for a given application and less expensive than antibodies. These plastic antibodies are raising increasing interest and one relatively unexplored domain in which they could outplay these advantages particularly well is cosmetics. Here, we present the use of a MIP as an active ingredient of a cosmetic product, for suppressing body odors. In a dermo‐cosmetic formulation, the MIP captures selectively the precursors of malodorous compounds, amidst a multitude of other molecules present in human sweat. These results pave the way to the fabrication of a novel generation of MIPs with improved selectivities in highly complex aqueous environments, and should be applicable to biotechnological and biomedical areas as well.
Palladium‐Catalyzed Oxidative Synthesis of α‐Acetoxylated Enones from Alkynes
Authors: Jiang Tuo , Quan Xu , Zhu Can , Andersson Pher G. , Bäckvall Jan‐E.
Published: April 2016

We report a palladium‐catalyzed oxidative functionalization of alkynes to generate α‐acetoxylated enones in one step. A range of functional groups are well‐tolerated in this reaction. Mechanistic studies, including the use of 18O‐labeled DMSO, revealed that the ketone oxygen atom in the product originates from DMSO.