bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Chronology of Late Quaternary Sequences From the Central Arctic Ocean Based on “Extinction Ages” of Their Excesses in 231Pa and 230Th
Authors: Hillaire‐Marcel C. , Ghaleb B. , de Vernal A. , Maccali J. , Cuny K. , Jacobel A. , Le Duc C. , McManus J.
Published: December 2017

Merging the late Quaternary Arctic paleoceanography into the Earth's global climate history remains challenging due to the lack of robust marine chronostratigraphies. Over ridges notably, low and variable sedimentation rates, scarce biogenic remains ensuing from low productivity and/or poor preservation, and oxygen isotope and paleomagnetic records differing from global stacks represent major impediments. However, as illustrate here based on consistent records from Mendeleev‐Alpha and Lomonosov Ridges, disequilibria between U‐series isotopes can provide benchmark ages. In such settings, fluxes of the particle‐reactive U‐daughter isotopes 230Th and 231Pa from the water column, are not unequivocally linked to sedimentation rates, but rather to sea‐ice rafting and brine production histories, thus to the development of sea‐ice factories over shelves during intervals of high relative sea level. The excesses in 230Th and 231Pa over fractions supported by their parent U‐isotopes, collapse down sedimentary sequences, due to radioactive decay, and provide radiometric benchmark ages of approximately 300 and 140 ka, respectively. These “extinction ages” point to mean sedimentation rates of ∼4.3 and ∼1.7 mm/ka, respectively, over the Lomonosov and Mendeleev Ridges, which are significantly lower than assumed in most recent studies, thus highlighting the need for revisiting current interpretations of Arctic lithostratigraphies in relation to the global‐scale late Quaternary climatostratigraphy.
Observations of Near‐Surface Current Shear Help Describe Oceanic Oil and Plastic Transport
Authors: Laxague Nathan J. M. , Özgökmen Tamay M. , Haus Brian K. , Novelli Guillaume , Shcherbina Andrey , Sutherland Peter , Guigand Cédric M. , Lund Björn , Mehta Sanchit , Alday Matias , Molemaker Jeroen
Published: December 2017

Plastics and spilled oil pose a critical threat to marine life and human health. As a result of wind forcing and wave motions, theoretical and laboratory studies predict very strong velocity variation with depth over the upper few centimeters of the water column, an observational blind spot in the real ocean. Here we present the first‐ever ocean measurements of the current vector profile defined to within 1 cm of the free surface. In our illustrative example, the current magnitude averaged over the upper 1 cm of the ocean is shown to be nearly four times the average over the upper 10 m, even for mild forcing. Our findings indicate that this shear will rapidly separate pieces of marine debris which vary in size or buoyancy, making consideration of these dynamics essential to an improved understanding of the pathways along which marine plastics and oil are transported.
Dynamics of Sunspot Series on Time Scales From Days to Years: Correlation of Sunspot Births, Variable Lifetimes, and Evolution of the High‐Frequency Spectral Component
Authors: Shapoval A. , Le Mouël J.‐L. , Shnirman M. , Courtillot V.
Published: December 2017

This paper explores some features of the dynamics of daily sunspot numbers on scales from days to years. We define higher and lower frequency energy components of the series that are related to periods ranging over 1 to 6 days and 6 days to 2 years, respectively. The lower frequency component is found to follow the solar activity, but the maxima of the higher frequency component are unexpectedly lower during the last epoch of high solar activity than during the preceding epoch of low solar activity. We also consider the birthrate of sunspot groups as another indicator of quickly varying components of the solar activity and show that it is the general growth of solar activity in the 1930–1940s that drives up this birthrate. We propose an autoregressive model that captures the opposite trends exhibited by the two representatives of the high‐frequency content, accurately reproduces the evolutions of the lower and higher frequency energy components, and replicates the shape of the curve representing the daily sunspot numbers. The three following hypotheses underlie the model construction: (1) proxy series of solar activity can be modeled by a random process with a modulated noise; (2) sunspot's birth and disappearance rates, both following the solar cycle, determine properties of this process; and (3) the births of sunspots are positively correlated in time during epochs of high solar activity. We find that the mean birthrate varies as a power function of the mean lifetime. Derived constraints could contribute to narrowing the choice of a proper solar dynamo model.
Validation and Analysis of Bounce Resonance Diffusion Coefficients
Authors: Li Xinxin , Tao Xin
Published: December 2017

Theoretical bounce resonance diffusion coefficients for waves generated near the equatorial plane are analyzed theoretically and validated numerically using guiding‐center test particle simulations. A previous study demonstrated numerically the sensitivity of the diffusion coefficients to the peak wave normal angle and the maximum wave latitude for electrons in bounce resonance with equatorially confined magnetosonic waves. We demonstrate analytically that the sensitivity of the diffusion coefficients to the peak wave normal angle is due to the narrow width of the wave normal angle distribution of the particular wave model used by the previous study. We also show that there is no dependence on the maximum latitude if particle's mirroring points are located within the wave boundary. By analyzing the contribution of each harmonic resonance to the total diffusion coefficients, we show that the discontinuities of the diffusion coefficients as a function of the equatorial pitch angle (α0) occur when the contribution of a harmonic resonance goes to 0. Using a two‐dimensional pitch angle and energy diffusion simulation, we demonstrate that bounce resonance with magnetosonic waves can cause pitch angle scattering of equatorially mirroring electrons, leading to a smooth variation of flux with α0 for α0∼90∘. We conclude that bounce resonance with magnetosonic waves might be an important mechanism in pitch angle scattering and acceleration of electrons in the radiation belt.
Flux Enhancements of > 30 keV Electrons at Low Drift Shells L < 1.2 During Last Solar Cycles
Authors: Suvorova A. V.
Published: December 2017

We present results of statistical analysis of enhancements of >30 keV electrons observed by the NOAA/POES satellites during solar cycles 23 and 24 (1998–2016) at low drift shells L < 1.2, so‐called forbidden zone. We collected 1,750 days (~25% of the total time) when fluxes of the forbidden energetic electrons (FEE) exceeded 103 (cm2 s sr)−1. We found 530 days, when FEE fluxes reached high intensity from 104 up to 107 (cm2 s sr)−1. It was found that the FEE enhancements were observed mostly often at the declining phases and solar minimum. More than 85% of the events occurred under fast solar wind (V > 450 km/s), high substorm activity (AL >150 nT), and enhanced interplanetary electric field perturbations (VδB > 1.5 mV/m). The FEE occurrence rate peaks around the local midnight. We have also found a quite unexpected annual variation of the FEE occurrence rate with a pronounced maximum from May to September, a minor peak in December–January, and minima at the equinoxes. The May–September peak, persisting at different solar cycle phases, was assumed to originate from high conductivity in the auroral ionosphere, which is controlled by the dipole tilt angle and provides better conditions for penetration of electric field perturbations into the inner magnetosphere. This allows explanation of the shape and amplitude of annual variation in the FEE occurrence rate from the convolution of the solar wind driver with the penetration conditions.
Super‐Alfvénic Propagation and Damping of Reconnection Onset Signatures
Authors: Sharma Pyakurel P. , Shay M. A. , Haggerty C. C. , Parashar T. N. , Drake J. F. , Cassak P. A. , Gary S. Peter
Published: December 2017

The quadrupolar out‐of‐plane Hall magnetic field generated during collisionless reconnection propagates away from the x line as a kinetic Alfvén wave (KAW). While it has been shown that this KAW carries substantial Poynting flux and propagates super‐Alfvenically, how this KAW damps as it propagates away from the x line is not well understood. In this study, this damping is examined using kinetic particle‐in‐cell simulations of antiparallel symmetric magnetic reconnection in a one‐dimensional current sheet equilibrium. In the reconnection simulations, the KAW wave vector has a typical magnitude comparable to an inverse fluid Larmor radius (effectively an inverse ion Larmor radius) and a direction of 85–89° relative to the local magnetic field. We find that the damping of the reconnection KAW is consistent with linear Landau damping results from a numerical Vlasov dispersion solver. This knowledge allows us to generalize our damping predictions to regions in the magnetotail and solar corona where the magnetic geometry can be approximated as a current sheet. For the magnetotail, the KAW from reconnection will not damp away before propagating the approximately 20 Earth radii associated with global magnetotail distances. For the solar corona, on the other hand, these KAWs will completely damp before reaching the distances comparable to the flare loop length.
Global Distribution and Variations of NO Infrared Radiative Flux and Its Responses to Solar Activity and Geomagnetic Activity in the Thermosphere
Authors: Tang Chaoli , Wei Yuanyuan , Liu Dong , Luo Tao , Dai Congming , Wei Heli
Published: December 2017

The global distribution and variations of NO infrared radiative flux (NO‐IRF) are presented during 2002–2016 in the thermosphere covering 100–280 km altitude based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data set. For investigating the spatial variations of the mutual relationship between NO‐IRF and solar activity, the altitude ranges from 100 km to 280 km are divided into 90 altitude bins, and the latitude regions of 83°S–83°N are divided into 16 latitude bins. By processing about 1.8E9 NO‐IRF observation values from about 5E6 vertical nighttime profiles recorded in SABER data set, we obtained more than 4.1E8 samples of NO‐IRF. The annual‐mean values of NO‐IRF are then calculated by all available NO‐IRF samples within each latitude and altitude bin. Local latitudinal maxima in NO‐IRF are found between 120 and 145 km altitude, and the maximum NO‐IRF located at polar regions are 3 times more than that of the minimum at equatorial region. The influences of solar and geomagnetic activity on the spatial variations of NO‐IRF are investigated. Both the NO‐IRF and its response to solar and geomagnetic activity show nearly symmetric distribution between the two hemispheres. It is demonstrated that the observed changes in NO‐IRF at altitudes between 100 and 225 km correlate well with the changes in solar activity. The NO‐IRF at solar maximum is about 4 times than that at solar minimum, and the current maximum of NO‐IRF in 2014 is less than 70% of the prior maximum in 2001. For the first time, the response ranges of the NO‐IRF to solar and geomagnetic activity at different altitudes and latitudes are reported.
GPS‐TEC Observation of Gravity Waves Generated in the Ionosphere During 21 August 2017 Total Solar Eclipse
Authors: Nayak Chinmaya , Yiğit Erdal
Published: December 2017

The present work investigates ionospheric effects of the 21 August 2017 total solar eclipse, particularly targeting eclipse‐generated gravity waves in the ionosphere. Ionospheric total electron content (TEC) derived from Global Positioning System (GPS) data obtained from a number of stations located both along and across the path of eclipse totality has been utilized for this purpose. Distinct gravity wave‐like signatures with wave periods around 20–90 min (with dominant peak at 25–30 min wave period) have been observed at all locations both in the path of totality and away from it. The observed gravity waves are more intense at locations closer to the path of totality, and the wave amplitudes decrease gradually with increasing distance from the path of totality. Our result highlights the manifestation of eclipse‐generated waves in the variability of the terrestrial ionosphere.
Variability of the Space‐Time Evolution of Slow Slip Events Off the Boso Peninsula, Central Japan, From 1996 to 2014
Authors: Fukuda Jun'ichi
Published: December 2017

Global Navigation Satellite System data are inverted to investigate the space‐time evolution of five Mw 6.6–6.7 slow slip events (SSEs) off the Boso Peninsula, central Japan, in 1996, 2002, 2007, 2011, and 2013–2014. Our analyses reveal that the nucleation style and space‐time evolution of slip vary among the five SSEs. The 2002, 2007, and 2011 SSEs nucleated more rapidly, with moment accelerations higher than those of the 1996 SSE by a factor of ∼2–6, and higher than those of the 2013–2014 SSE by an order of magnitude. Furthermore, the 2002, 2007, and 2011 SSEs exhibited more rapid temporal variations in their slip and moment rates and showed larger seismic moments and higher maximum slip rates than the 1996 and 2013–2014 SSEs, suggesting that the overall evolution of the SSEs is correlated with the nucleation style. The along‐strike expansion/propagation of slip is identified for the five SSEs, revealing that the expansion/propagation patterns vary from event to event. The earthquake swarms accompanying the SSEs occurred near the downdip edge of high‐slip‐rate areas, and the seismicity migrated during slow slip with directions and speeds similar to those of the slip expansion/propagation. These space‐time correlations between seismicity and slow slip suggest that the earthquake swarms were triggered by stress changes due to slow slip. The relative timing between the onsets of the SSEs and their associated seismicity varies from event to event and appears to be correlated with the nucleation style of the SSEs.
On the Grain Size Sensitivity of Olivine Rheology
Authors: Jain Chhavi , Korenaga Jun , Karato Shun‐ichiro
Published: December 2017

Using the Markov chain Monte Carlo (MCMC) inversion technique of Mullet et al. (2015), we reassess the validity of the conventionally accepted values of the grain size exponent of diffusion creep in olivine aggregates. A systematic and comprehensive analysis of individual experimental runs taken from three widely cited studies reveals that these data do not tightly constrain the grain size exponent or any other flow law parameter for diffusion and dislocation creep. Our analysis indicates that large data uncertainties can cause inversion results to deviate significantly from true values because of the covariance between the grain size and stress exponents, and that even resolving a grain size exponent of 2 from 3 is difficult. The versatility of our MCMC inversion technique can, however, be exploited to improve this situation by identifying optimal conditions for future experimental studies. Because the uncertainties of the grain size and stress exponents are highly correlated, for example, increasing the range of grain size variation can help better constrain both exponents simultaneously.
The Role of Coseismic Coulomb Stress Changes in Shaping the Hard Link Between Normal Fault Segments
Authors: Hodge M. , Fagereng Å , Biggs J.
Published: December 2017

The mechanism and evolution of fault linkage is important in the growth and development of large faults. Here we investigate the role of coseismic stress changes in shaping the hard links between parallel normal fault segments (or faults), by comparing numerical models of the Coulomb stress change from simulated earthquakes on two en echelon fault segments to natural observations of hard‐linked fault geometry. We consider three simplified linking fault geometries: (1) fault bend, (2) breached relay ramp, and (3) strike‐slip transform fault. We consider scenarios where either one or both segments rupture and vary the distance between segment tips. Fault bends and breached relay ramps are favored where segments underlap or when the strike‐perpendicular distance between overlapping segments is less than 20% of their total length, matching all 14 documented examples. Transform fault linkage geometries are preferred when overlapping segments are laterally offset at larger distances. Few transform faults exist in continental extensional settings, and our model suggests that propagating faults or fault segments may first link through fault bends or breached ramps before reaching sufficient overlap for a transform fault to develop. Our results suggest that Coulomb stresses arising from multisegment ruptures or repeated earthquakes are consistent with natural observations of the geometry of hard links between parallel normal fault segments.
Assessment of NPP VIIRS Albedo Over Heterogeneous Crop Land in Northern China
Authors: Wu Xiaodan , Wen Jianguang , Xiao Qing , Yu Yunyue , You Dongqin , Hueni Andreas
Published: December 2017

In this paper, the accuracy of Suomi National Polar‐orbiting Partnership Visible Infrared Imaging Radiometer Suite (VIIRS) land surface albedo, which is derived from the direct estimation algorithm, was assessed using ground‐based albedo observations from a wireless sensor network over a heterogeneous cropland in the Huailai station, northern China. Data from six nodes spanning 2013–2014 over vegetation, bare soil, and mixed terrain surfaces were utilized to provide ground reference at VIIRS pixel scale. The performance of VIIRS albedo was also compared with Global LAnd Surface Satellite (GLASS) and Moderate Resolution Imaging Spectroradiometer (MODIS) albedos (Collection 5 and 6). The results indicate that the current granular VIIRS albedo has a high accuracy with a root‐mean‐square error of 0.02 for typical land covers. They are significantly correlated with ground references indicated by a correlation coefficient (R) of 0.73. The VIIRS albedo shows distinct advantages to GLASS and MODIS albedos over bare soil and mixed‐cover surfaces, while it is inferior to the other two products over vegetated surfaces. Furthermore, its time continuity and the ability to capture the abrupt change of surface albedo are better than that of GLASS and MODIS albedo.
Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica
Authors: Wlostowski A. N. , Gooseff M. N. , Adams B. J.
Published: December 2017

Antarctic soil ecosystems are strongly controlled by abiotic habitat variables. Regional climate change in the McMurdo Dry Valleys is expected to cause warming over the next century, leading to an increase in frequency of freeze‐thaw cycling in the soil habitat. Previous studies show that physiological stress associated with freeze‐thaw cycling adversely affects invertebrate populations by decreasing abundance and positively selecting for larger body sizes. However, it remains unclear whether or not climate warming will indeed enhance the frequency of annual freeze‐thaw cycling and associated physiological stresses. This research quantifies the frequency, rate, and spatial heterogeneity of active layer freezing to better understand how regional climate change may affect active layer soil thermodynamics, and, in turn, affect soil macroinvertebrate communities. Shallow active layer temperature, specific conductance, and soil moisture were observed along natural wetness gradients. Field observations show that the frequency and rate of freeze events are nonlinearly related to freezable soil moisture (θf). Over a 2 year period, soils at θf < 0.080 m3/m3 experienced between 15 and 35 freeze events and froze rapidly compared to soils with θf > 0.080 m3/m3, which experienced between 2 and 6 freeze events and froze more gradually. A numerical soil thermodynamic model is able to simulate observed freezing rates across a range of θf, reinforcing a well‐known causal relationship between soil moisture and active layer freezing dynamics. Findings show that slight increases in soil moisture can potentially offset the effect of climate warming on exacerbating soil freeze‐thaw cycling.
Cost‐Loss Analysis of Ensemble Solar Wind Forecasting: Space Weather Use of Terrestrial Weather Tools
Authors: Henley E. M. , Pope E. C. D.
Published: December 2017

This commentary concerns recent work on solar wind forecasting by Owens and Riley (2017, https://doi.org/10.1002/2017SW001679). The approach taken makes effective use of tools commonly used in terrestrial weather—notably, via use of a simple model—generation of an “ensemble” forecast, and application of a “cost‐loss” analysis to the resulting probabilistic information, to explore the benefit of this forecast to users with different risk appetites. This commentary aims to highlight these useful techniques to the wider space weather audience and to briefly discuss the general context of application of terrestrial weather approaches to space weather.
Real‐Time Optimal Flood Control Decision Making and Risk Propagation Under Multiple Uncertainties
Authors: Zhu Feilin , Zhong Ping‐An , Sun Yimeng , Yeh William W.‐G.
Published: December 2017

Multiple uncertainties exist in the optimal flood control decision‐making process, presenting risks involving flood control decisions. This paper defines the main steps in optimal flood control decision making that constitute the Forecast‐Optimization‐Decision Making (FODM) chain. We propose a framework for supporting optimal flood control decision making under multiple uncertainties and evaluate risk propagation along the FODM chain from a holistic perspective. To deal with uncertainties, we employ stochastic models at each link of the FODM chain. We generate synthetic ensemble flood forecasts via the martingale model of forecast evolution. We then establish a multiobjective stochastic programming with recourse model for optimal flood control operation. The Pareto front under uncertainty is derived via the constraint method coupled with a two‐step process. We propose a novel SMAA‐TOPSIS model for stochastic multicriteria decision making. Then we propose the risk assessment model, the risk of decision‐making errors and rank uncertainty degree to quantify the risk propagation process along the FODM chain. We conduct numerical experiments to investigate the effects of flood forecast uncertainty on optimal flood control decision making and risk propagation. We apply the proposed methodology to a flood control system in the Daduhe River basin in China. The results indicate that the proposed method can provide valuable risk information in each link of the FODM chain and enable risk‐informed decisions with higher reliability.
A comparison of two pencil beam scanning treatment planning systems for proton therapy
Authors: Langner Ulrich W. , Mundis Michelle , Strauss Dan , Zhu Mingyao , Mossahebi Sina
Published: December 2017

Objective

Analytical dose calculation algorithms for Eclipse and Raystation treatment planning systems (TPS), as well as a Raystation Monte Carlo model are compared to corresponding measured point doses.

Method

The TPS were modeled with the same beam data acquired during commissioning. Thirty‐five typical plans were made with each planning system, 31 without range shifter and four with a 5 cm range shifter. Point doses in these planes were compared to measured doses.

Results

The mean percentage difference for all plans between Raystation and Eclipse were 1.51 ± 1.99%. The mean percentage difference for all plans between TPS models and measured values are −2.06 ± 1.48% for Raystation pencil beam (PB), −0.59 ± 1.71% for Eclipse and −1.69 ± 1.11% for Raystation monte carlo (MC). The distribution for the patient plans were similar for Eclipse and Raystation MC with a P‐value of 0.59 for a two tailed unpaired t‐test and significantly different from the Raystation PB model with P = 0.0013 between Raystation MC and PB. All three models faired markedly better if plans with a 5 cm range shifter were ignored. Plan comparisons with a 5 cm range shifter give differences between Raystation and Eclipse of 3.77 ± 1.82%. The mean percentage difference for 5 cm range shifter plans between TPS models and measured values are −3.89 ± 2.79% for Raystation PB, −0.25 ± 3.85% for Eclipse and 1.55 ± 1.95% for Raystation MC.

Conclusion

Both Eclipse and Raystation PB TPS are not always accurate within ±3% for a 5 cm range shifters or for small targets. This was improved with the Raystation MC model. The point dose calculations of Eclipse, Raystation PB, and Raystation MC compare within ±3% to measured doses for the other scenarios tested.
MRI biomarkers of proximal nerve injury in CIDP
Authors: Lichtenstein Thorsten , Sprenger Alina , Weiss Kilian , Slebocki Karin , Cervantes Barbara , Karampinos Dimitrios , Maintz David , Fink Gereon R. , Henning Tobias D. , Lehmann Helmar C.
Published: December 2017

Objective

To evaluate the utility of nerve diffusion tensor imaging (DTI), nerve cross‐sectional area, and muscle magnetic resonance imaging (MRI) multiecho Dixon for assessing proximal nerve injury in chronic inflammatory demyelinating polyneuropathy (CIDP).

Methods

In this prospective observational cohort study, 11 patients with CIDP and 11 healthy controls underwent a multiparametric MRI protocol with DTI of the sciatic nerve and assessment of muscle proton‐density fat fraction of the biceps femoris and the quadriceps femoris muscles by multiecho Dixon MRI. Patients were longitudinally evaluated by MRI, clinical examination, and nerve conduction studies at baseline and after 6 months.

Results

In sciatic nerves of CIDP patients, mean cross‐sectional area was significantly higher and fractional anisotropy value was significantly lower, compared to controls. In contrast, muscle proton‐density fat fraction was significantly higher in thigh muscles of patients with CIDP, compared to controls. MRI parameters showed high reproducibility at baseline and 6 months.

Interpretation

Advanced MRI parameters demonstrate subclinical proximal nerve damage and intramuscular fat accumulation in CIDP. Data suggest DTI and multiecho Dixon MRI might be useful in estimating axonal damage and neurogenic muscle changes in CIDP.
Mesoporous Caged‐γ‐AlOOH‐Double‐Stranded RNA Analog Complexes for Cancer Immunotherapy
Authors: Li Xia , Shenashen Mohamed A. , Wang Xiupeng , Ito Atsuo , Taniguchi Akiyoshi , EI‐Safty Sherif A.
Published: December 2017

Alum exhibits the superior biocompatibility in the history of human healthcare, as the only FDA‐approved inorganic adjuvant in most human vaccines. However, up to now, there are few reports about the in‐depth research between its nanostructure and carrier properties in vitro and in vivo. In this study, the caged architecture of uniform mesoporous γ‐AlOOH nanorods (MANRs) comprises realigned pores and open windows at the edges, 1D tubular tunnels, and oxyhydroxide layer that can serve as carriers for cancer immunotherapy. Compared with commercial alum, the MANRs exhibit a higher loading amount of a model cancer antigen and a stronger intracellular uptake by THP‐1‐differentiated macrophage‐like cells in vitro. Compared with commercial alum and soluble ovalbumin, the MANRs loaded with a model cancer antigen, ovalbumi, and an immunopotentiator, double‐stranded RNA analog poly(I:C) markedly increase the anticancer immunity and CD4+ and CD8+ T cell populations in mouse splenocytes in vivo. The MANRs are promising as an adjuvant substance in cancer immunotherapy for clinical use.
Toward High Strength and High Electrical Conductivity in Super‐Aligned Carbon Nanotubes Reinforced Copper
Authors: Xiong Lunqiao , Liu Kangwei , Shuai Jing , Hou Zecheng , Zhu Lin , Li Wenzhen
Published: December 2017

The miniaturization of electronic products is drawing higher demand in the strength and conductivity of conductors. This work demonstrates the possibility of substantially increasing the dislocation density in copper to enhance the strength of super‐aligned carbon nanotubes (SACNTs) reinforced copper matrix composites (SACNT/Cu) without compromising the electrical conductivity. High strain is introduced into pure copper and SACNT/Cu by accumulative roll‐bonding (ARB) process up to 16 cycles at ambient temperature. SACNTs with initial laminated distribution turn out to be dispersed uniformly with maintained directional arrangement inside the copper matrix after ARB, which can then effectively block the motion of dislocations. Therefore, large number of dislocations propagated by large strains can be accumulated without subdivision. The accumulated dislocations will result into strain hardening, which is the major strengthening mechanism in SACNT/Cu after ARB. Furthermore, the contribution of dislocations to resistivity increase is little, thus maintaining high electrical conductivity. As a result, a high tensile strength (505 MPa) combined with a high electrical conductivity (90% IACS) is achieved in large‐sized composite sheet.
Illuminating Origins of Impact Energy Dissipation in Mechanical Metamaterials
Authors: Vuyk Peter , Cui Shichao , Harne Ryan L.
Published: December 2017

Elastomeric mechanical metamaterials have revealed striking ability to attenuate shock loads at the macroscopic level. Reports suggest that this capability is associated with the reversible elastic buckling of internal beam constituents observed in quasistatic characterizations. Yet, the presence of buckling members induces non‐affine response at the microscale, so that clear understanding of the exact energy dissipation mechanisms remains clouded. In this report, the authors examine a mechanical metamaterial that exhibits both micro‐ and macroscopic deformations under impact loads and devise an experimental method to visualize the resulting energy dissipation mechanisms. By illuminating the dynamic distribution of strain in the metamaterial, the authors uncover a rational way to program the macroscopic deformation and enhance impact mitigation properties. The results emphasize that mechanical metamaterials clearly integrate materials science and structural engineering, encouraging future interdisciplinary studies to capitalize on the opportunities.
Toward Functional 3D Architectured Platform: Advanced Approach to Anchor Functional Metal Oxide onto 3D Printed Scaffold
Authors: Choi Junghyun , Kim Patrick Joo Hyun , Seo Jihoon , Kwon Jiseok , Lee Sangkyu , Song Taeseup
Published: December 2017

The authors first report the three‐dimensional (3D) structured CeO2–PLA scaffold using a 3D printing methodology. The scaffold is prepared by decorating functional metal‐oxide nanoparticles onto the 3D‐printed polylactic acid (PLA) platform via an electrostatic interaction and is applied to the applications for photochemical degradation. As‐designed CeO2–PLA scaffold shows high photocatalytic degradation performance toward methyl orange under a light irradation. Furthermore, the CeO2–PLA scaffold shows reasonable degradation performance even after it is washed and reevaluated; this result demonstrates the benefit of 3D‐printed CeO2–PLA scaffold that it can be recycled several times without losing the catalysts.
Potassium‐Ion Battery Anode Materials Operating through the Alloying–Dealloying Reaction Mechanism
Authors: Sultana Irin , Rahman Md Mokhlesur , Chen Ying , Glushenkov Alexey M.
Published: December 2017

Anode materials that operate via the alloying–dealloying reaction mechanism are well known in established and maturing battery systems such as lithium‐ion and sodium‐ion batteries. Recently, a new type of metal‐ion battery that utilizes K+ ions in its operating principle has attracted significant attention due to a possibility of building high voltage cells using an abundant potassium ionic shuttle. Establishing promising electrode materials is of paramount importance for this new type of battery. This feature article summarizes available early results on the alloying–dealloying anode materials in potassium electrochemical cells. Based on original research (some data are presented for the first time) and independently published literature, experimental results on silicon, tin, phosphorus, antimony, and lead‐containing anodes are critically discussed. The electrochemical properties, charge storage mechanisms, and achievable capacities are considered. The results are compared with the behaviors of the same materials in lithium and sodium cells, and the importance of the volumetric parameters of electrodes is emphasized. Finally, a number of further research directions in these interesting anode materials are suggested. The feature article provides a useful reference for the growing number of researchers and specialists working in the field of emerging metal‐ion batteries with non‐lithium chemistries.
Functionalized Cubic Mesoporous Silica as a Non‐Chemodosimetric Fluorescence Probe and Adsorbent for Selective Detection and Removal of Bisulfite Anions along with Toxic Metal Ions
Authors: Chatterjee Sobhan , Paital Alok Ranjan
Published: December 2017

Dual signaling and remediation systems for detection and adsorption of toxic analytes have gained more attention over sensory probes only. However, most of the sensors for bisulfites are chemodosimetric probes, which are irreversible and having drawbacks of absolute selectivity, recyclability, and solubility in a pure aqueous system. To address above drawbacks a new non‐chemodosimetric probe material with a strong hydrogen bonding pocket for bisulfites is developed. Synthesis of cubic mesoporous silica by a modified Stober process followed by functionalization with 2,2′‐(((((3‐(triethoxysilyl)propyl)azanediyl)bis(methylene))bis(2,1‐phenylene))bis(oxy))bis(N‐(4‐((E)‐phenyldiazenyl)phenyl)acetamide) (AZOL) has given a fluorogenic silica probe material SiO2@AZOL. This material shows selectivity toward bisulfite anion (limit of detection (LOD): 64 ppb) and Hg2+, Cd2+, Cu2+, and Zn2+ cations (LOD: 126, 95, 14, and 27 ppb, respectively) among various analytes. The adsorption studies for these toxic analytes (HSO3
−, Hg2+, Cd2+, Cu2+, and Zn2+) show an extraction efficiency of around 99% and adsorption capacities of 873, 630, 633, 260, and 412 mg g−1, respectively. Spectroscopic studies along with adsorption, striping, and regeneration studies reveal that this material is a recyclable sensory cum adsorbent material for these toxic analytes. Moreover, this material can be used as a sensitive probe material for determination of HSO3
− levels in various sugar samples.
Easily Processable and Programmable Responsive Semi‐Interpenetrating Liquid Crystalline Polymer Network Coatings with Changing Reflectivities and Surface Topographies
Authors: Kragt Augustinus J. J. , Broer Dirk J. , Schenning Albertus P. H. J.
Published: December 2017

The fabrication of stimulus‐responsive coatings that change both reflectivity and topography is hampered by the lack of easy processable, patternable, and programmable elastomers. Here, an easily applied reflective coating based on a semi‐interpenetrating polymer network composed of a liquid crystal elastomer and a liquid crystal network (>15 wt%) is reported. The reflective wavelength of these polysiloxane elastomer photonic coatings can be readily programed by the concentration of chiral reactive mesogen dopant that forms the network. The coatings show a fast and reversible decrease in reflection band intensity with increasing temperature, which can be tuned by the polymer network density. In addition, hierarchical surface relief structures are prepared, which can be reversibly changed with temperature.
Optical Chemical Barcoding Based on Polarization Controlled Plasmonic Nanopixels
Authors: Langley Daniel Peter , Balaur Eugeniu , Hwang Yongsop , Sadatnajafi Catherine , Abbey Brian
Published: December 2017

Plasmonic devices offer the possibility of passively detecting changes in local chemistry that opens up a wide range of applications from molecular sensing to monitoring water quality. Conventional plasmonics have previously shown great promise as nanoscale chemical sensors through detection of small variations in the local refractive index (RI). The motivation behind using plasmonics for these applications includes the fact that detection is entirely passive and the devices themselves can be readily miniaturized. Previously, a lack of any control over the output of these devices, has fundamentally limited their application to chemicals which produce clearly identifiable resonances within the range of detection. Here it is demonstrated that microfluidic devices, incorporating polarization‐controlled plasmonic nanopixels, allow the device response to be tuned to the particular analyte of interest, anywhere within the visible spectrum. This dramatically increases the effective dynamic range and allows local variations in RI to be perceived directly as color changes by the human eye. Active control over the output of the device also enables clear differentiation between a number of different analytes, paving the way for plasmonics to be used for a wide range of real‐world chemical sensing applications.
An In Situ Formed, Dual‐Phase Cathode with a Highly Active Catalyst Coating for Protonic Ceramic Fuel Cells
Authors: Chen Yu , Yoo Seonyoung , Pei Kai , Chen Dongchang , Zhang Lei , deGlee Ben , Murphy Ryan , Zhao Bote , Zhang Yanxiang , Chen Yan , Liu Meilin
Published: December 2017

Composite cathodes of solid oxide fuel cells (SOFCs) are normally fabricated by mechanical mixing of electronic‐ and ionic‐conducting phases. Here, a dual‐phase SOFC cathode, composed of perovskite PrNi0.5Mn0.5O3 (PNM) and exsoluted fluorite PrOx particles, produced in situ through a glycine–nitrate solution combustion process, is reported. When applied as the cathode for a BaZr0.1Ce0.7Y0.1Yb0.1O3‐based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area‐specific resistance of 0.052 Ω cm2 at 700 °C) and remarkable long‐term stability when operated at a cell voltage of 0.7 V for ≈500 h using H2 as fuel and ambient air as oxidant. The excellent performance is attributed to the proton‐conducting BaPrO3‐based coating and high‐concentration oxygen vacancies of a Ba‐doped PNM surface coating, produced by the reaction between the cathode and Ba from the electrolyte (via evaporation or diffusion), as confirmed by detailed X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory‐based calculations.
From Fragility to Flexibility: Construction of Hydrogel Bridges toward a Flexible Multifunctional Free‐Standing CaCO3 Film
Authors: Yuan Xue , Nie Wu‐Cheng , Xu Chen , Wang Xiao‐Hui , Xiao Qian , Song Fei , Wang Xiu‐Li , Wang Yu‐Zhong
Published: December 2017

Free‐standing CaCO3 materials are an important member in biological systems because of their existence in many natural organisms such as nacre, shell, and crustacean cuticle. However, toughness of those artificial mineral films is sacrificed once their inorganic content is up to 90%, thus free‐standing characteristics have seldom been achieved for CaCO3 films, let alone their real applications. Herein a fast and simple method for constructing hydrogel “bridges” for CaCO3 microparticles is presented, developing highly flexible free‐standing CaCO3 films with only 5% organic content. Such integrated films have underwater superoleophobicity and self‐cleaning function, which guarantee their repeated application in oil/water separation. Furthermore, heavy metal ions can be efficiently removed by simple filtration with the films. Because of the self‐similar structure, the films are able to resist mechanical abrasion without losing the anti‐wetting property and separation efficiency. The free‐standing CaCO3 films are put forward for the first time to practical application, demonstrating the strategy can bring a brilliant prospect to artificial biomineral materials.
2D Dual‐Metal Zeolitic‐Imidazolate‐Framework‐(ZIF)‐Derived Bifunctional Air Electrodes with Ultrahigh Electrochemical Properties for Rechargeable Zinc–Air Batteries
Authors: Wang Tingting , Kou Zongkui , Mu Shichun , Liu Jingping , He Daping , Amiinu Ibrahim Saana , Meng Wen , Zhou Kui , Luo Zhixiong , Chaemchuen Somboon , Verpoort Francis
Published: December 2017

Here first a 2D dual‐metal (Co/Zn) and leaf‐like zeolitic imidazolate framework (ZIF‐L)‐pyrolysis approach is reported for the low‐cost and facile preparation of Co nanoparticles encapsulated into nitrogen‐doped carbon nanotubes (Co‐N‐CNTs). Importantly, the reasonable Co/Zn molar ratio in the ZIF‐L is the key to the emergence of the encapsulated microstructure. Specifically, high‐dispersed cobalt nanoparticles are fully encapsulated in the tips of N‐CNTs, leading to the full formation of highly active Co–N–C moieties for oxygen reduction and evolution reactions (ORR and OER). As a result, the obtained Co‐N‐CNTs present superior electrocatalytic activity and stability toward ORR and OER over the commercial Pt/C and IrO2 as well as most reported metal‐organic‐framework‐derived catalysts, respectively. Remarkably, as bifunctional air electrodes of the Zn–air battery, it also shows extraordinary charge–discharge performance. The present concept will provide a guideline for screening novel 2D metal‐organic frameworks as precursors to synthesize advanced multifunctional nanomaterials for cross‐cutting applications.
Stimuli‐Responsive Nucleic Acid‐Based Polyacrylamide Hydrogel‐Coated Metal–Organic Framework Nanoparticles for Controlled Drug Release
Authors: Chen Wei‐Hai , Liao Wei‐Ching , Sohn Yang Sung , Fadeev Michael , Cecconello Alessandro , Nechushtai Rachel , Willner Itamar
Published: December 2017

The synthesis of doxorubicin‐loaded metal–organic framework nanoparticles (NMOFs) coated with a stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel is described. The formation of the hydrogel is stimulated by the crosslinking of two polyacrylamide chains, PA and PB, that are functionalized with two nucleic acid hairpins (4) and (5) using the strand‐induced hybridization chain reaction. The resulting duplex‐bridged polyacrylamide hydrogel includes the anti‐ATP (adenosine triphosphate) aptamer sequence in a caged configuration. The drug encapsulated in the NMOFs is locked by the hydrogel coating. In the presence of ATP that is overexpressed in cancer cells, the hydrogel coating is degraded via the formation of the ATP–aptamer complex, resulting in the release of doxorubicin drug. In addition to the introduction of a general means to synthesize drug‐loaded stimuli‐responsive nucleic acid‐based polyacrylamide hydrogel‐coated NMOFs hybrids, the functionalized NMOFs resolve significant limitations associated with the recently reported nucleic acid‐gated drug‐loaded NMOFs. The study reveals substantially higher loading of the drug in the hydrogel‐coated NMOFs as compared to the nucleic acid‐gated NMOFs and overcomes the nonspecific leakage of the drug observed with the nucleic‐acid‐protected NMOFs. The doxorubicin‐loaded, ATP‐responsive, hydrogel‐coated NMOFs reveal selective and effective cytotoxicity toward MDA‐MB‐231 breast cancer cells, as compared to normal MCF‐10A epithelial breast cells.
Oxygen Clusters Distributed in Graphene with “Paddy Land” Structure: Ultrahigh Capacitance and Rate Performance for Supercapacitors
Authors: Liu Zheng , Jiang Lili , Sheng Lizhi , Zhou Qihang , Wei Tong , Zhang Bingsen , Fan Zhuangjun
Published: December 2017

The introduction of surface functional groups onto graphene can provide additional pseudocapacitance for supercapacitors. However, the compensation for the loss of electrical conductivity arising from the disruption of the conjugated system remains a big challenge. Here, a novel strategy is reported for the design of oxygen clusters distributed in graphene with “paddy land” structure via a low‐temperature annealing process. Moreover, the distribution, content, and variety of oxygen groups and the conductivity of reduced graphene oxide (RGO) can be easily adjusted by annealing temperature and time. First‐principles calculations demonstrate that “paddy land” structure exhibits conjugated carbon network, ultralow HOMO–LUMO gap, and long span of atomic charge values, which are beneficial for the enhanced pseudocapacitance and rate performance. As a result, the functionalized graphene (GO‐160‐8D) exhibits high specific capacitance of 436 F g−1 at 0.5 A g−1, exceeding the values of previously reported RGO materials, as well as excellent rate performance (261 F g−1 at 50 A g−1) and cycling stability (94% of capacitance retention after 10 000 cycles). The findings may open a door for finely controlling the location and density of functionalities on graphene for applications in energy storage and conversion fields via a green and energy‐efficient process.
Transduction Methods for Cytosolic Delivery of Proteins and Bioconjugates into Living Cells
Authors: Chiper Manuela , Niederreither Karen , Zuber Guy
Published: December 2017

The human organism and its constituting cells rely on interplay between multiple proteins exerting specific functions. Progress in molecular biotechnologies has facilitated the production of recombinant proteins. When administrated to patients, recombinant proteins can provide important healthcare benefits. To date, most therapeutic proteins must act from the extracellular environment, with their targets being secreted modulators or extracellular receptors. This is because proteins cannot passively diffuse across the plasma membrane into the cytosol. To expand the scope of action of proteins for cytosolic targets (representing more than 40% of the genome) effective methods assisting protein cytosolic entry are being developed. To date, direct protein delivery is extremely tedious and inefficient in cultured cells, even more so in animal models of pathology. Novel techniques are changing this limitation, as recently developed in vitro methods can robustly convey large amount of proteins into cell cultures. Moreover, advances in protein formulation or protein conjugates are slowly, but surely demonstrating efficiency for targeted cytosolic entry of functional protein in vivo in tumor xenograft models. In this review, various methods and recently developed techniques for protein transport into cells are summarized. They are put into perspective to address the challenges encountered during delivery.
A Novel Acoustomicrofluidic Nebulization Technique Yielding New Crystallization Morphologies
Authors: Ahmed Heba , Lee Lillian , Darmanin Connie , Yeo Leslie Y.
Published: December 2017

A novel acoustic microfluidic nebulization platform is demonstrated, which, due to its unique ability to access intermediate evaporation rate regimes—significantly faster than that in slow solvent evaporation but considerably below that achieved in spray drying, is capable of producing novel crystal morphologies that have yet to be reported in both model inorganic and organic systems. In addition, the potential for simultaneously encapsulating single crystals within a biodegradable polymeric coating in a single simultaneous step together with the crystallization process as the solvent evaporates during nebulization is briefly shown. The platform not only has the potential to be highly scalable by employing a large number of these low‐cost miniature devices in parallel to achieve industrially relevant particle production rates, but could also be advantageous over conventional spray drying in terms of energy utilization, given the tremendous efficiency associated with the high‐frequency ultrasonic microdevice as well as its ambient temperature operation.