bluuebunny/crossref_metadata_2025 huggingface dataset:
Tumor initiating cells induce Cxcr4-mediated infiltration of pro-tumoral macrophages into the brain
Authors: Chia Kelda , Mazzolini Julie , Mione Marina , Sieger Dirk
Published: February 2018

It is now clear that microglia and macrophages are present in brain tumors, but whether or how they affect initiation and development of tumors is not known. Exploiting the advantages of the zebrafish (Danio rerio) model, we showed that macrophages and microglia respond immediately upon oncogene activation in the brain. Overexpression of human AKT1 within neural cells of larval zebrafish led to a significant increase in the macrophage and microglia populations. By using a combination of transgenic and mutant zebrafish lines, we showed that this increase was caused by the infiltration of peripheral macrophages into the brain mediated via Sdf1b-Cxcr4b signaling. Intriguingly, confocal live imaging reveals highly dynamic interactions between macrophages/microglia and pre-neoplastic cells, which do not result in phagocytosis of pre-neoplastic cells. Finally, depletion of macrophages and microglia resulted in a significant reduction of oncogenic cell proliferation. Thus, macrophages and microglia show tumor promoting functions already during the earliest stages of the developing tumor microenvironment.
A simple method of equine limb force vector analysis and its potential applications
Authors: Hobbs Sarah Jane , Robinson Mark A. , Clayton Hilary M.
Published: February 2018

Background

Ground reaction forces (GRF) measured during equine gait analysis are typically evaluated by analyzing discrete values obtained from continuous force-time data for the vertical, longitudinal and transverse GRF components. This paper describes a simple, temporo-spatial method of displaying and analyzing sagittal plane GRF vectors. In addition, the application of statistical parametric mapping (SPM) is introduced to analyse differences between contra-lateral fore and hindlimb force-time curves throughout the stance phase. The overall aim of the study was to demonstrate alternative methods of evaluating functional (a)symmetry within horses.

Methods

GRF and kinematic data were collected from 10 horses trotting over a series of four force plates (120 Hz). The kinematic data were used to determine clean hoof contacts. The stance phase of each hoof was determined using a 50 N threshold. Vertical and longitudinal GRF for each stance phase were plotted both as force-time curves and as force vector diagrams in which vectors originating at the centre of pressure on the force plate were drawn at intervals of 8.3 ms for the duration of stance. Visual evaluation was facilitated by overlay of the vector diagrams for different limbs. Summary vectors representing the magnitude (VecMag) and direction (VecAng) of the mean force over the entire stance phase were superimposed on the force vector diagram. Typical measurements extracted from the force-time curves (peak forces, impulses) were compared with VecMag and VecAng using partial correlation (controlling for speed). Paired samplest-tests (left v. right diagonal pair comparison and high v. low vertical force diagonal pair comparison) were performed on discrete and vector variables using traditional methods and Hotelling’sT2tests on normalized stance phase data using SPM.

Results

Evidence from traditional statistical tests suggested that VecMag is more influenced by the vertical force and impulse, whereas VecAng is more influenced by the longitudinal force and impulse. When used to evaluate mean data from the group of ten sound horses, SPM did not identify differences between the left and right contralateral limb pairs or between limb pairs classified according to directional asymmetry. When evaluating a single horse, three periods were identified during which differences in the forces between the left and right forelimbs exceeded the critical threshold (p < .01).

Discussion

Traditional statistical analysis of 2D GRF peak values, summary vector variables and visual evaluation of force vector diagrams gave harmonious results and both methods identified the same inter-limb asymmetries. As alpha was more tightly controlled using SPM, significance was only found in the individual horse althoughT2plots followed the same trends as discrete analysis for the group.

Conclusions

The techniques of force vector analysis and SPM hold promise for investigations of sidedness and asymmetry in horses.
Diversity in root growth responses to moisture deficit in young faba bean (Vicia faba L.) plants
Authors: Belachew Kiflemariam Yehuala , Nagel Kerstin A. , Fiorani Fabio , Stoddard Frederick L.
Published: February 2018

Background

Soil moisture deficiency causes yield reduction and instability in faba bean (Vicia faba L.) production. The extent of sensitivity to drought stress varies across accessions originating from diverse moisture regimes of the world. Hence, we conducted successive greenhouse experiments in pots and rhizotrons to explore diversity in root responses to soil water deficit.

Methods

A set of 89 accessions from wet and dry growing regions of the world was defined according to the Focused Identification of Germplasm Strategy and screened in a perlite-sand medium under well watered conditions in a greenhouse experiment. Stomatal conductance, canopy temperature, chlorophyll concentration, and root and shoot dry weights were recorded during the fifth week of growth. Eight accessions representing the range of responses were selected for further investigation. Starting five days after germination, they were subjected to a root phenotyping experiment using the automated phenotyping platform GROWSCREEN-Rhizo. The rhizotrons were filled with peat-soil under well watered and water limited conditions. Root architectural traits were recorded five, 12, and 19 days after the treatment (DAT) began.

Results

In the germplasm survey, accessions from dry regions showed significantly higher values of chlorophyll concentration, shoot and root dry weights than those from wet regions. Root and shoot dry weight as well as seed weight, and chlorophyll concentration were positively correlated with each other. Accession DS70622 combined higher values of root and shoot dry weight than the rest. The experiment in GROWSCREEN-Rhizo showed large differences in root response to water deficit. The accession by treatment interactions in taproot and second order lateral root lengths were significant at 12 and 19 DAT, and the taproot length was reduced up to 57% by drought. The longest and deepest root systems under both treatment conditions were recorded by DS70622 and DS11320, and total root length of DS70622 was three times longer than that of WS99501, the shortest rooted accession. The maximum horizontal distribution of a root system and root surface coverage were positively correlated with taproot and total root lengths and root system depth. DS70622 and WS99501 combined maximum and minimum values of these traits, respectively. Thus, roots of DS70622 and DS11320, from dry regions, showed drought-avoidance characteristics whereas those of WS99501 and Mèlodie/2, from wet regions, showed the opposite.

Discussion

The combination of the germplasm survey and use of GROWSCREEN-Rhizo allowed exploring of adaptive traits and detection of root phenotypic markers for potential drought avoidance. The greater root system depth and root surface coverage, exemplified by DS70622 and DS11320, can now be tested as new sources of drought tolerance.
Biomarker potential of ST6GALNAC3 and ZNF660 promoter hypermethylation in prostate cancer tissue and liquid biopsies
Authors: Haldrup Christa , Pedersen Anne L. , Øgaard Nadia , Strand Siri H. , Høyer Søren , Borre Michael , Ørntoft Torben F. , Sørensen Karina D.
Published: February 2018

Current diagnostic and prognostic tools for prostate cancer (PC) are suboptimal, leading to overdiagnosis and overtreatment. Aberrant promoter hypermethylation of specific genes has been suggested as novel candidate biomarkers for PC that may improve diagnosis and prognosis. We here analyzed ST6GALNAC3 and ZNF660 promoter methylation in prostate tissues, and ST6GALNAC3, ZNF660, CCDC181, and HAPLN3 promoter methylation in liquid biopsies. First, using four independent patient sample sets, including a total of 110 nonmalignant (NM) and 705 PC tissue samples, analyzed by methylation‐specific qPCR or methylation array, we found that hypermethylation of ST6GALNAC3 and ZNF660 was highly cancer‐specific with areas under the curve (AUC) of receiver operating characteristic (ROC) curve analysis of 0.917–0.995 and 0.846–0.903, respectively. Furthermore, ZNF660 hypermethylation was significantly associated with biochemical recurrence in two radical prostatectomy (RP) cohorts of 158 and 392 patients and remained significant also in the subsets of patients with Gleason score ≤7 (univariate Cox regression and log‐rank tests, P < 0.05), suggesting that ZNF660 methylation analysis can potentially help to stratify low‐/intermediate‐grade PCs into indolent vs. more aggressive subtypes. Notably, ZNF660 hypermethylation was also significantly associated with poor overall and PC‐specific survival in the RP cohort (n = 158) with long clinical follow‐up available. Moreover, as proof of principle, we successfully detected highly PC‐specific hypermethylated circulating tumor DNA (ctDNA) for ST6GALNAC3, ZNF660, HAPLN3, and CCDC181 in liquid biopsies (serum) from 27 patients with PC vs. 10 patients with BPH, using droplet digital methylation‐specific PCR analysis. Finally, we generated a three‐gene (ST6GALNAC3/CCDC181/HAPLN3) ctDNA hypermethylation model, which detected PC with 100% specificity and 67% sensitivity. In conclusion, we here for the first time demonstrate diagnostic biomarker potential of ST6GALNAC3 and ZNF660 methylation, as well as prognostic biomarker potential of ZNF660. Furthermore, we show that hypermethylation of four genes can be detected in ctDNA in liquid biopsies (serum) from patients with PC.
Violation of Field Line Conservation and Associated Spatial Scales in Particle‐in‐Cell Simulations and MMS Data
Authors: Wendel Deirdre E. , Liu Yi‐Hsin , Giles Barbara L. , Torbert Roy B.
Published: February 2018

For the first time, space flight technology exists to detect, in situ, violation of magnetic field line conservation. The violation of magnetic line conservation on scales smaller than the system size is a necessary and sufficient condition for finite magnetic field reconnection. We demonstrate that violation of line conservation produces a detectable, structured signature both in particle‐in‐cell simulations of reconnection and in data from the Magnetospheric Multi‐Scale mission. In particle‐in‐cell simulations of asymmetric reconnection, the quantity—which we call M—that identifies this violation achieves significant values in electron skin depth‐scale layers that extend away from the separator, with higher values emerging on the low‐density, high‐magnetic‐field side of the current sheet. At the separator, M owes largely to perpendicular gradients in the parallel electric field, while it attains its highest values away from the separator in dispersed, layered structures associated with gradients in the perpendicular nonideal electric field and electron transport. Sub‐ion scale bipolar forms of the quantity also appear further from the separator. In two MMS burst data intervals detecting the electron diffusion region, we find that M exceeds measurement uncertainties both at the separator and near the separatrices. One interval has highly sheared reconnecting fields and the other a stronger guide field. For one event, we determine the location and scale of M and the inner electron diffusion region relative to electron outflows and the magnetic separatrices. The measure can therefore serve as a potent diagnostic for magnetic reconnection in space measurements.
Determining L‐M‐N Current Sheet Coordinates at the Magnetopause From Magnetospheric Multiscale Data
Authors: Denton R. E. , Sonnerup B. U. Ö. , Russell C. T. , Hasegawa H. , Phan T.‐D. , Strangeway R. J. , Giles B. L. , Ergun R. E , Lindqvist P.‐A. , Torbert R. B. , Burch J. L , Vines S. K.
Published: February 2018

We discuss methods to determine L‐M‐N coordinate systems for current sheet crossings observed by the Magnetospheric Multiscale (MMS) spacecraft mission during ongoing reconnection, where eL is the direction of the reconnecting component of the magnetic field, B, and eN is normal to the magnetopause. We present and test a new hybrid method, with eL estimated as the maximum variance direction of B (MVAB) and eN as the direction of maximum directional derivative of B, and then adjust these directions to be perpendicular. In the best case, only small adjustment is needed. Results from this method, applied to an MMS crossing of the dayside magnetopause at 1305:45 UT on 16 October 2015, are discussed and compared with those from other methods for which eN is obtained by other means. Each of the other evaluations can be combined with eL from MVAB in a generalized hybrid approach to provide an L‐M‐N system. The quality of the results is judged by eigenvalue ratios, constancy of directions using different data segments and methods, and expected sign and magnitude of the normal component of B. For this event, the hybrid method appears to produce eN accurate to within less than 10°. We discuss variance analysis using the electric current density, J, or the J × B force, which yield promising results, and minimum Faraday residue analysis and MVAB alone, which can be useful for other events. We also briefly discuss results from our hybrid method and MVAB alone for a few other MMS reconnection events.
Observation and Numerical Simulation of Cavity Mode Oscillations Excited by an Interplanetary Shock
Authors: Takahashi Kazue , Lysak Robert , Vellante Massimo , Kletzing Craig A. , Hartinger Michael D. , Smith Charles W.
Published: February 2018

Cavity mode oscillations (CMOs) are basic magnetohydrodynamic eigenmodes in the magnetosphere predicted by theory and are expected to occur following the arrival of an interplanetary shock. However, observational studies of shock‐induced CMOs have been sparse. We present a case study of a dayside ultralow‐frequency wave event that exhibited CMO properties. The event occurred immediately following the arrival of an interplanetary shock at 0829 UT on 15 August 2015. The shock was observed in the solar wind by the Time History of Events and Macroscale Interactions during Substorms‐B and ‐C spacecraft, and magnetospheric ultralow‐frequency waves were observed by multiple spacecraft including the Van Allen Probe‐A and Van Allen Probe‐B spacecraft, which were located in the dayside plasmasphere at L ∼1.4 and L ∼ 2.4, respectively. Both Van Allen Probes spacecraft detected compressional poloidal mode oscillations at ∼13 mHz (fundamental) and ∼26 mHz (second harmonic). At both frequencies, the azimuthal component of the electric field (Eϕ) lagged behind the compressional component of the magnetic field (Bμ) by ∼90°. The frequencies and the Eϕ‐Bμ relative phase are in good agreement with the CMOs generated in a dipole magnetohydrodynamic simulation that incorporates a realistic plasma mass density distribution and ionospheric boundary condition. The oscillations were also detected on the ground by the European quasi‐Meridional Magnetometer Array, which was located near the magnetic field footprints of the Van Allen Probes spacecraft.
Jovian Auroral Ion Precipitation: Field‐Aligned Currents and Ultraviolet Emissions
Authors: Houston S. J. , Ozak N. , Young J. , Cravens T. E. , Schultz D. R.
Published: February 2018

A model is described for the transport of magnetospheric oxygen ions with low charge state and energies up to several MeV/nucleon (MeV/u) as they precipitate into Jupiter's polar atmosphere. A revised and updated hybrid Monte Carlo model originally developed by Ozak et al. (2010, https://doi.org/10.1029/2010JA015635) is used to model the Jovian X‐ray aurora. The current model uses a wide range of incident oxygen ion energies (10 keV/u to 5 MeV/u) and the most up‐to‐date collision cross sections. In addition, the effects of the secondary electrons generated from the heavy ion precipitation are included using a two‐stream transport model that computes the secondary electron fluxes and their escape from the atmosphere. The model also determines H2 Lyman‐Werner band emission intensities, including a predicted spectrum and the associated color ratio. Implications of the new model results for interpretation of data from National Aeronautics and Space Administration's Juno mission are discussed. In particular, the model predicts that for a 2 MeV/u oxygen ion energy input of 10 mW/m2: (1) escaping electrons are produced with an energy range from 1 eV to 4 keV, which is a smaller range than previous models by Ozak et al. (2013, https://doi.org/10.1002/2013GL50812) predicted, (2) H2 band emission rates of 75 kR are generated, similar to previous estimates, and (3) a newly calculated Lyman and Werner band color ratio of 10 is expected. The color ratios are put into a context of various methane number density distributions.
A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere
Authors: Malaspina David M. , Ukhorskiy Aleksandr , Chu Xiangning , Wygant John
Published: February 2018

Now that observations have conclusively established that the inner magnetosphere is abundantly populated with kinetic electric field structures and nonlinear waves, attention has turned to quantifying the ability of these structures and waves to scatter and accelerate inner magnetospheric plasma populations. A necessary step in that quantification is determining the distribution of observed structure and wave properties (e.g., occurrence rates, amplitudes, and spatial scales). Kinetic structures and nonlinear waves have broadband signatures in frequency space, and consequently, high‐resolution time domain electric and magnetic field data are required to uniquely identify such structures and waves as well as determine their properties. However, most high‐resolution fields data are collected with a strong bias toward high‐amplitude signals in a preselected frequency range, strongly biasing observations of structure and wave properties. In this study, an ∼45 min unbroken interval of 16,384 samples/s field burst data, encompassing an electron injection event, is examined. This data set enables an unbiased census of the kinetic structures and nonlinear waves driven by this electron injection, as well as determination of their “typical” properties. It is found that the properties determined using this unbiased burst data are considerably different than those inferred from amplitude‐biased burst data, with significant implications for wave‐particle interactions due to kinetic structures and nonlinear waves in the inner magnetosphere.
Stimulated Mirror Instability From the Interplay of Anisotropic Protons and Electrons, and their Suprathermal Populations
Authors: Shaaban S. M. , Lazar M. , Astfalk P. , Poedts S.
Published: February 2018

Mirror instability driven by the temperature anisotropy of protons can offer a plausible explanation for the mirror‐like fluctuations observed in planetary magnetosheaths. In the present paper we invoke a realistic kinetic approach which can reproduce nonthermal features of plasma particles reported by the observations, i.e., temperature anisotropies and suprathermal populations. Seeking accuracy, a numerical analysis is performed using an advanced code named DSHARK, recently proposed to resolve the linear dispersion and stability for an arbitrary propagation in bi‐Kappa distributed electron‐proton plasmas. The stimulating effect of the anisotropic bi‐Maxwellian electrons reported in Remya et al. (2013, https://doi.org/10.1002/jgra.50091) is markedly enhanced in the presence of suprathermal electrons described by the bi‐Kappa distribution functions. The influence of suprathermal protons is more temperate, but overall, present results demonstrate that these sources of free energy provide natural conditions for a stimulated mirror instability, more efficient than predicted before and capable to compete with other instabilities (e.g., the electromagnetic ion‐cyclotron instability) and mechanisms of relaxation.
Toward a Global Horizontal and Vertical Elastic Load Deformation Model Derived from GRACE and GNSS Station Position Time Series
Authors: Chanard Kristel , Fleitout Luce , Calais Eric , Rebischung Paul , Avouac Jean‐Philippe
Published: February 2018

We model surface displacements induced by variations in continental water, atmospheric pressure, and nontidal oceanic loading, derived from the Gravity Recovery and Climate Experiment (GRACE) for spherical harmonic degrees two and higher. As they are not observable by GRACE, we use at first the degree‐1 spherical harmonic coefficients from Swenson et al. (2008, https://doi.org/10.1029/2007JB005338). We compare the predicted displacements with the position time series of 689 globally distributed continuous Global Navigation Satellite System (GNSS) stations. While GNSS vertical displacements are well explained by the model at a global scale, horizontal displacements are systematically underpredicted and out of phase with GNSS station position time series. We then reestimate the degree 1 deformation field from a comparison between our GRACE‐derived model, with no a priori degree 1 loads, and the GNSS observations. We show that this approach reconciles GRACE‐derived loading displacements and GNSS station position time series at a global scale, particularly in the horizontal components. Assuming that they reflect surface loading deformation only, our degree‐1 estimates can be translated into geocenter motion time series. We also address and assess the impact of systematic errors in GNSS station position time series at the Global Positioning System (GPS) draconitic period and its harmonics on the comparison between GNSS and GRACE‐derived annual displacements. Our results confirm that surface mass redistributions observed by GRACE, combined with an elastic spherical and layered Earth model, can be used to provide first‐order corrections for loading deformation observed in both horizontal and vertical components of GNSS station position time series.
Crustal Structure of the Ionian Basin and Eastern Sicily Margin: Results From a Wide‐Angle Seismic Survey
Authors: Dellong David , Klingelhoefer Frauke , Kopp Heidrun , Graindorge David , Margheriti Lucia , Moretti Milena , Murphy Shane , Gutscher Marc‐Andre
Published: February 2018

In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo‐Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south‐east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab roll‐back. This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial. This study focuses on the deep crustal structure of the eastern Sicily margin and the Malta Escarpment. We present two two‐dimensional P wave velocity models obtained from forward modeling of wide‐angle seismic data acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. The interpretation of the velocity models suggests that the tear fault is located east of the Malta Escarpment, along the Alfeo fault system.
Land Ice Freshwater Budget of the Arctic and North Atlantic Oceans: 1. Data, Methods, and Results
Authors: Bamber J. L. , Tedstone A. J. , King M. D. , Howat I. M. , Enderlin E. M. , van den Broeke M. R. , Noel B.
Published: February 2018

The freshwater budget of the Arctic and sub‐polar North Atlantic Oceans has been changing due, primarily, to increased river runoff, declining sea ice and enhanced melting of Arctic land ice. Since the mid‐1990s this latter component has experienced a pronounced increase. We use a combination of satellite observations of glacier flow speed and regional climate modeling to reconstruct the land ice freshwater flux from the Greenland ice sheet and Arctic glaciers and ice caps for the period 1958–2016. The cumulative freshwater flux anomaly exceeded 6,300 ± 316 km3by 2016. This is roughly twice the estimate of a previous analysis that did not include glaciers and ice caps outside of Greenland and which extended only to 2010. From 2010 onward, the total freshwater flux is about 1,300 km3/yr, equivalent to 0.04 Sv, which is roughly 40% of the estimated total runoff to the Arctic for the same time period. Not all of this flux will reach areas of deep convection or Arctic and Sub‐Arctic seas. We note, however, that the largest freshwater flux anomalies, grouped by ocean basin, are located in Baffin Bay and Davis Strait. The land ice freshwater flux displays a strong seasonal cycle with summer time values typically around five times larger than the annual mean. This will be important for understanding the impact of these fluxes on fjord circulation, stratification, and the biogeochemistry of, and nutrient delivery to, coastal waters.
Lower‐Stratospheric Control of the Frequency of Sudden Stratospheric Warming Events
Authors: Martineau Patrick , Chen Gang , Son Seok‐Woo , Kim Joowan
Published: February 2018

The sensitivity of stratospheric polar vortex variability to the basic‐state stratospheric temperature profile is investigated by performing a parameter sweep experiment with a dry dynamical core general circulation model where the equilibrium temperature profiles in the polar lower and upper stratosphere are systematically varied. It is found that stratospheric variability is more sensitive to the temperature distribution in the lower stratosphere than in the upper stratosphere. In particular, a cold lower stratosphere favors a strong time‐mean polar vortex with a large daily variability, promoting frequent sudden stratospheric warming events in the model runs forced with both wavenumber‐1 and wavenumber‐2 topographies. This sensitivity is explained by the control exerted by the lower‐stratospheric basic state onto fluxes of planetary‐scale wave activity from the troposphere to the stratosphere, confirming that the lower stratosphere can act like a valve for the upward propagation of wave activity. It is further shown that with optimal model parameters, stratospheric polar vortex climatology and variability mimicking Southern and Northern Hemisphere conditions are obtained with both wavenumber‐1 and wavenumber‐2 topographies.
Spatial and Temporal Variability and Trends in 2001–2016 Global Fire Activity
Authors: Earl Nick , Simmonds Ian
Published: February 2018

Fire regimes across the globe have great spatial and temporal variability, and these are influence by many factors including anthropogenic management, climate, and vegetation types. Here we utilize the satellite‐based “active fire” product, from Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, to statistically analyze variability and trends in fire activity from the global to regional scales. We split up the regions by economic development, region/geographical land use, clusters of fire‐abundant areas, or by religious/cultural influence. Weekly cycle tests are conducted to highlight and quantify part of the anthropogenic influence on fire regime across the world. We find that there is a strong statistically significant decline in 2001–2016 active fires globally linked to an increase in net primary productivity observed in northern Africa, along with global agricultural expansion and intensification, which generally reduces fire activity. There are high levels of variability, however. The large‐scale regions exhibit either little change or decreasing in fire activity except for strong increasing trends in India and China, where rapid population increase is occurring, leading to agricultural intensification and increased crop residue burning. Variability in Canada has been linked to a warming global climate leading to a longer growing season and higher fuel loads. Areas with a strong weekly cycle give a good indication of where fire management is being applied most extensively, for example, the United States, where few areas retain a natural fire regime.
Diverse Lithologies and Alteration Events on the Rim of Noachian‐Aged Endeavour Crater, Meridiani Planum, Mars: In Situ Compositional Evidence
Authors: Mittlefehldt David W. , Gellert Ralf , vanBommel Scott , Ming Douglas W. , Yen Albert S. , Clark Benton C. , Morris Richard V. , Schröder Christian , Crumpler Larry S. , Grant John A. , Jolliff Bradley L. , Arvidson Raymond E. , Farrand William H. , Herkenhoff Kenneth E. , Bell James F. , Cohen Barbara A. , Klingelhöfer Göstar , Schrader Christian M. , Rice James W.
Published: February 2018

We report the results of geological studies by the Opportunity Mars rover on the Endeavour Crater rim. Four major units occur in the region (oldest to youngest): the Matijevic, Shoemaker, Grasberg, and Burns formations. The Matijevic formation, consisting of fine‐grained clastic sediments, is the only pre‐Endeavour‐impact unit and might be part of the Noachian etched units of Meridiani Planum. The Shoemaker formation is a heterogeneous polymict impact breccia; its lowermost member incorporates material eroded from the underlying Matijevic formation. The Shoemaker formation is a close analog to the Bunte Breccia of the Ries Crater, although the average clast sizes are substantially larger in the latter. The Grasberg formation is a thin, fine‐grained, homogeneous sediment unconformably overlying the Shoemaker formation and likely formed as an airfall deposit of unknown areal extent. The Burns formation sandstone overlies the Grasberg, but compositions of the two units are distinct; there is no evidence that the Grasberg formation is a fine‐grained subfacies of the Burns formation. The rocks along the Endeavour Crater rim were affected by at least four episodes of alteration in the Noachian and Early Hesperian: (i) vein formation and alteration of preimpact Matijevic formation rocks, (ii) low‐water/rock alteration along the disconformity between the Matijevic and Shoemaker formations, (iii) alteration of the Shoemaker formation along fracture zones, and (iv) differential mobilization of Fe and Mn, and CaSO4‐vein formation in the Grasberg and Shoemaker formations. Episodes (ii) and (iii) possibly occurred together, but (i) and (iv) are distinct from either of these.
Seasonal Shoreline Variability Induced by Subtidal Water Level Fluctuations at Reef‐Fringed Beaches
Authors: Segura L. E. , Hansen J. E. , Lowe R. J.
Published: February 2018

The comparative role of subtidal water level and wave height variations on seasonal shoreline changes was investigated at a reef‐fringed beach in southwestern Australia. The data set consisted of continuous sea level and wave records, monthly topographic beach surveys over a 2 year period, and bimonthly high‐resolution aerial images over a 7 year period. Shorelines were extracted from images and topographic surveys, and then an empirical orthogonal function (EOF) analysis was applied to both data sets. The temporal amplitudes of the first EOF mode of the image‐derived shoreline data set (∼60% of the variance) were most correlated with 30 day averages of the subtidal water level (variations up to ±0.2 m) driven by geostrophic adjustment of the Leeuwin Current. The geostrophic response of the Leeuwin Current was found to be further correlated with the phasing of the El Niño–Southern Oscillation, leading to higher water levels during La Niña and lower levels during El Niño, which as a consequence resulted in interannual variations in the shoreline behavior reflected in the first EOF mode. The temporal amplitudes of the second EOF mode (∼20% of the variance) were most correlated with 50 day averages in offshore wave height. Our results indicate that the seasonal beach response was primarily influenced by seasonal variations in offshore water level rather than by wave heights as has been generally observed in exposed beaches. A simple EOF‐based model is presented, which reproduces the alongshore‐variable shoreline response and its seasonal and interannual modulation due to El Niño–Southern Oscillation events over the study period.
Climate Change Impacts on Net Ecosystem Productivity in a Subtropical Shrubland of Northwestern México
Authors: Verduzco Vivian S. , Vivoni Enrique R. , Yépez Enrico A. , Rodríguez Julio C. , Watts Christopher J. , Tarin Tonantzin , Garatuza‐Payán Jaime , Robles‐Morua Agustin , Ivanov Valeriy Y.
Published: February 2018

The sensitivity of semiarid ecosystems to climate change is not well understood due to competing effects of soil and plant‐mediated carbon fluxes. Limited observations of net ecosystem productivity (NEP) under rising air temperature and CO2and altered precipitation regimes also hinder climate change assessments. A promising avenue for addressing this challenge is through the application of numerical models. In this work, we combine a mechanistic ecohydrological model and a soil carbon model to simulate soil and plant processes in a subtropical shrubland of northwest México. Due to the influence of the North American monsoon, the site exhibits net carbon losses early in the summer and net carbon gains during the photosynthetically active season. After building confidence in the simulations through comparisons with eddy covariance flux data, we conduct a series of climate change experiments for near‐future (2030–2045) scenarios that test the impact of meteorological changes and CO2fertilization relative to historical conditions (1990–2005). Results indicate that reductions in NEP arising from warmer conditions are effectively offset by gains in NEP due to the impact of higher CO2on water use efficiency. For cases with higher summer rainfall and CO2fertilization, climate change impacts lead to an increase of ~25% in NEP relative to historical conditions (mean of 66 g C m−2). Net primary production and soil respiration derived from decomposition are shown to be important processes that interact to control NEP and, given the role of semiarid ecosystems in the global carbon budget, deserve attention in future simulation efforts of ecosystem fluxes.
Multicomponent Supported Membrane Microarray for Monitoring Spatially Resolved Cellular Signaling Reactions
Authors: Biswas Kabir H. , Zhongwen Chen , Dubey Alok Kumar , Oh Dongmyung , Groves Jay T.
Published: February 2018

Cells sense biochemical as well as mechanical signals from their microenvironment by engaging multiple receptors. In many cases, multiple receptors operate in concert, and it can be misleading to attempt to isolate a single ligand–receptor interaction. Supported lipid membranes are employed to reconstitute a number of cell receptor systems. Efforts are also made to fabricate membrane microarrays presenting multiple ligands in a spatially segregated manner. However, such membrane multiplexing methods are generally limited by complex instrumentation and scalability. Here, a straightforward method is presented to produce centimeter‐scale membrane microarrays displaying multiple, spatially segregated membrane‐anchored protein ligands suitable for live single‐cell studies. The method is based on stochastic membrane fusion and subsequent diffusion‐mediated mixing of their lipid content. The result is the delivery of membrane contents into spatially segregated membrane corrals. Utilizing the technology developed here, this work probes the recruitment of an adaptor protein, Shc1, to epidermal growth factor receptor (EGFR) and EphA2 receptors and shows that activation of EGFR results in a decrease in the recruitment of protein to activate EphA2 same cell.
DNA Computing Boosted by a Cationic Copolymer
Authors: Shimada Naohiko , Saito Ken , Miyata Takafumi , Sato Hiroki , Kobayashi Satoshi , Maruyama Atsushi
Published: February 2018

The huge information storage capability of DNA and its ability to self‐assemble can be harnessed to enable massively parallel computing in a small space. DNA‐based logic gates are designed that rely on DNA strand displacement reactions; however, computation is slow due to time‐consuming DNA reassembly processes and prone to failure as DNA is susceptible to degradation by nucleases and under certain solution conditions. Here, it is shown that the presence of a cationic copolymer boosts the speed of DNA logic gate operations that involve multiple and parallel strand displacement reactions. Two kinds of DNA molecular operations, one based on a translator gate and one on a seesaw gate, are successfully enhanced by the copolymer without tuning of computing conditions or DNA sequences. The copolymer markedly reduces operation times from hours to minutes. Moreover, the copolymer enhances nuclease resistance.
Self‐Assembled Peptide‐Based Nanomaterials for Biomedical Imaging and Therapy
Authors: Qi Guo‐Bin , Gao Yu‐Juan , Wang Lei , Wang Hao
Published: February 2018

Peptide‐based materials are one of the most important biomaterials, with diverse structures and functionalities. Over the past few decades, a self‐assembly strategy is introduced to construct peptide‐based nanomaterials, which can form well‐controlled superstructures with high stability and multivalent effect. More recently, peptide‐based functional biomaterials are widely utilized in clinical applications. However, there is no comprehensive review article that summarizes this growing area, from fundamental research to clinic translation. In this review, the recent progress of peptide‐based materials, from molecular building block peptides and self‐assembly driving forces, to biomedical and clinical applications is systematically summarized. Ex situ and in situ constructed nanomaterials based on functional peptides are presented. The advantages of intelligent in situ construction of peptide‐based nanomaterials in vivo are emphasized, including construction strategy, nanostructure modulation, and biomedical effects. This review highlights the importance of self‐assembled peptide nanostructures for nanomedicine and can facilitate further knowledge and understanding of these nanosystems toward clinical translation.
Vitrimer Elastomer‐Based Jigsaw Puzzle‐Like Healable Triboelectric Nanogenerator for Self‐Powered Wearable Electronics
Authors: Deng Jianan , Kuang Xiao , Liu Ruiyuan , Ding Wenbo , Wang Aurelia C. , Lai Ying‐Chih , Dong Kai , Wen Zhen , Wang Yaxian , Wang Lili , Qi H. Jerry , Zhang Tong , Wang Zhong Lin
Published: February 2018

Functional polymers possess outstanding uniqueness in fabricating intelligent devices such as sensors and actuators, but they are rarely used for converting mechanical energy into electric power. Here, a vitrimer based triboelectric nanogenerator (VTENG) is developed by embedding a layer of silver nanowire percolation network in a dynamic disulfide bond‐based vitrimer elastomer. In virtue of covalent dynamic disulfide bonds in the elastomer matrix, a thermal stimulus enables in situ healing if broken, on demand reconfiguration of shape, and assembly of more sophisticated structures of VTENG devices. On rupture or external damage, the structural integrity and conductivity of VTENG are restored under rapid thermal stimulus. The flexible and stretchable VTENG can be scaled up akin to jigsaw puzzles and transformed from 2D to 3D structures. It is demonstrated that this self‐healable and shape‐adaptive VTENG can be utilized for mechanical energy harvesters and self‐powered tactile/pressure sensors with extended lifetime and excellent design flexibility. These results show that the incorporation of organic materials into electronic devices can not only bestow functional properties but also provide new routes for flexible device fabrication.
Dual‐Peak Absorbing Semiconducting Copolymer Nanoparticles for First and Second Near‐Infrared Window Photothermal Therapy: A Comparative Study
Authors: Jiang Yuyan , Li Jingchao , Zhen Xu , Xie Chen , Pu Kanyi
Published: February 2018

Near‐infrared (NIR) light is widely used for noninvasive optical diagnosis and phototherapy. However, current research focuses on the first NIR window (NIR‐I, 650–950 nm), while the second NIR window (NIR‐II, 1000–1700 nm) is far less exploited. The development of the first organic photothermal nanoagent (SPNI‐II) with dual‐peak absorption in both NIR windows and its utilization in photothermal therapy (PTT) are reported herein. Such a nanoagent comprises a semiconducting copolymer with two distinct segments that respectively and identically absorb NIR light at 808 and 1064 nm. With the photothermal conversion efficiency of 43.4% at 1064 nm generally higher than other inorganic nanomaterials, SPNI‐II enables superior deep‐tissue heating at 1064 nm over that at 808 nm at their respective safety limits. Model deep‐tissue cancer PTT at a tissue depth of 5 mm validates the enhanced antitumor effect of SPNI‐II when shifting laser irradiation from the NIR‐I to the NIR‐II window. The good biodistribution and facile synthesis of SPNI‐II also allow it to be doped with an NIR dye for fluorescence‐imaging‐guided NIR‐II PTT through systemic administration. Thus, this study paves the way for the development of new polymeric nanomaterials to advance phototherapy.
Hybrid Metamaterial Absorber Platform for Sensing of CO2 Gas at Mid‐IR
Authors: Hasan Dihan , Lee Chengkuo
Published: February 2018

Application of two major classes of CO2 gas sensors, i.e., electrochemical and nondispersive infrared is predominantly impeded by the poor selectivity and large optical interaction length, respectively. Here, a novel “hybrid metamaterial” absorber platform is presented by integrating the state‐of‐the‐art complementary metal–oxide–semiconductor compatible metamaterial with a smart, gas‐selective‐trapping polymer for highly selective and miniaturized optical sensing of CO2 gas in the 5–8 µm mid‐IR spectral window. The sensor offers a minimum of 40 ppm detection limit at ambient temperature on a small footprint (20 µm by 20 µm), fast response time (≈2 min), and low hysteresis. As a proof‐of‐concept, net absorption enhancement of 0.0282%/ppm and wavelength shift of 0.5319 nm ppm−1 are reported. Furthermore, the gas‐ selective smart polymer is found to enable dual‐mode multiplexed sensing for crosschecking and validation of gas concentration on a single platform. Additionally, unique sensing characteristics as determined by the operating wavelength and bandwidth are demonstrated. Also, large differential response of the metamaterial absorber platform for all‐optical monitoring is explored. The results will pave the way for a physical understanding of metamaterial‐based sensing when integrated with the mid‐IR detector for readout and extending the mid‐IR functionalities of selective polymers for the detection of technologically relevant gases.
Advanced Characterization Techniques for Sodium‐Ion Battery Studies
Authors: Shadike Zulipiya , Zhao Enyue , Zhou Yong‐Ning , Yu Xiqian , Yang Yong , Hu Enyuan , Bak Seongmin , Gu Lin , Yang Xiao‐Qing
Published: February 2018

Sodium (Na)‐ion batteries (NIBs) are considered promising alternative candidates to the well‐commercialized lithium‐ion batteries, especially for applications in large‐scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium‐ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in‐depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight into the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. In this review, a comprehensive overview of both static (ex situ) and real‐time (in situ or in operando) techniques for studying the NIBs is provided. Special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.
Dual Functional Electron‐Selective Contacts Based on Silicon Oxide/Magnesium: Tailoring Heterointerface Band Structures while Maintaining Surface Passivation
Authors: Tong Hui , Yang Zhenhai , Wang Xixi , Liu Zhaolang , Chen Zhenxin , Ke Xiaoxing , Sui Manling , Tang Jiang , Yu Tianbao , Ge Ziyi , Zeng Yuheng , Gao Pingqi , Ye Jichun
Published: February 2018

Silicon (Si)‐based dopant‐free heterojunction solar cells (SCs) featuring carrier‐selective contacts (CSCs) have attracted considerable interest due to the extreme simplifications in their device structure and manufacturing procedure. However, these SCs are limited by the unsatisfactory contact properties on both sides of the junction, and their efficiencies are not comparable with those of commercially available Si SCs. In this report, a high‐performance silicon‐oxide/magnesium (SiOx/Mg) electron‐selective contact (ESC) design is described. Combining an ultrathin SiOx and a low work function Mg layer, the novel ESC simultaneously yields low recombinative and resistive losses. In addition, deposition of Mg on SiOx relaxes the restriction on the threshold thickness of the SiOx for electron tunneling and therefore broadens the optimization space for rear‐sided passivation. Meanwhile, hole‐selective contact with boosted light harvesting and suppressed interfacial recombination is achieved by forming a fully conformal contact between the conducting poly(3,4‐ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) and periodic Si pyramid arrays. With the double‐sided carrier‐selective contact designs, PEDOT: PSS/Si/SiOx/Mg SCs with efficiency of 15% are finally obtained via a totally dopant‐free processing. Subsequent calculations further indicate a pathway for the improvement of these contacts toward an efficiency that is competitive with conventionally diffused pn junction SCs.
Solid‐State Sodium Batteries
Authors: Zhao Chenglong , Liu Lilu , Qi Xingguo , Lu Yaxiang , Wu Feixiang , Zhao Junmei , Yu Yan , Hu Yong‐Sheng , Chen Liquan
Published: February 2018

Rechargeable Na‐ion batteries (NIBs) are attractive large‐scale energy storage systems compared to Li‐ion batteries due to the substantial reserve and low cost of sodium resources. The recent rapid development of NIBs will no doubt accelerate the commercialization process. As one of the indispensable components in current battery systems, organic liquid electrolytes are widely used for their high ionic conductivity and good wettability, but the low thermal stability, especially the easy flammability and leakage make them at risk of safety issues. The booming solid‐state batteries with solid‐state electrolytes (SSEs) show promise as alternatives to organic liquid systems due to their improved safety and higher energy density. However, several challenges including low ionic conductivity, poor wettability, low stability/incompatibility between electrodes and electrolytes, etc., may degrade performance, hindering the development of practical applications. In this review, an overview of Na‐ion SSEs is first outlined according to the classification of solid polymer electrolytes, composite polymer electrolytes, inorganic solid electrolytes, etc. Furthermore, the current challenges and critical perspectives for the potential development of solid‐state sodium batteries are discussed in detail.