bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Characterization of Impact Crater Materials on the Moon: Changes in Topographic Roughness and Thermophysical Properties With Age
Authors: Wang Juntao , Kreslavsky Mikhail A. , Liu Jianzhong , Head James W. , Zhang Ke , Kolenkina Maria M. , Zhang Li
Published: September 2020

Impact craters are the dominant features on the Moon, and their degradation with time is the most common geological process on this body. This work is aimed at detailed quantitative characterization of this process. We quantitatively characterize crater materials by (1) the topographic roughness calculated from Lunar Orbiter Laser Altimeter and (2) rock abundances and nighttime soil temperatures derived from Diviner measurements. In contrast to preceding works, we separately consider crater material subunits: central peaks, floors, walls, and continuous ejecta to study their degradation in detail. We mapped totally 4,770 individual crater material subunits. All subunits of the youngest craters are characterized by increased roughness, rock abundance, and soil temperature. These parameters decrease with age and tend toward equilibrium, stable state; the continuous ejecta reach equilibrium more rapidly than other subunits. Kilometer‐baseline roughness of crater walls in the lunar maria is higher than in the highlands. Rock abundances and soil temperatures of the walls and floors of simple craters in the maria are also higher than in the highlands. We attribute these trends to differences in the mechanical properties of the target materials. Although the properties studied are not exact proxies for age, they can be used to assess individual age predictions; for example, several craters that were erroneously classified as Copernican have been detected. We also found that the unusual thermophysical signature of the walls of the Late Imbrian crater Bonpland D is due to recent regolith flows that could have been caused by a strong, shallow seismic event.
Detailed Bathymetry of the Continental Shelf Beneath the Getz Ice Shelf, West Antarctica
Authors: Cochran James R. , Tinto Kirsty J. , Bell Robin E.
Published: September 2020

The Getz Ice Shelf (GIS) produces major amounts of basal meltwater due to intrusions of warm modified Circumpolar Deep Water (mCDW) beneath the ice shelf. However, multiple cavity openings and complex geography mean that knowledge of bathymetry beneath the GIS is required to understand ice/ocean interactions. We invert NASA airborne gravity data to obtain bathymetry beneath the ice shelf. Our gravity/geology‐constrained bathymetry is a significant advance on Bedmap2 bathymetry. The sub‐ice shelf bathymetry consists of three cavities separated by topographic ridges extending from the ice shelf front to the grounding line. Passages allowing limited circulation of shallow (≲400 meters below sea level [mbsl]) water between cavities are present, but deeper water is confined to individual cavities. Within each cavity, bathymetric troughs (>900 mbsl) extend from the ice shelf front to subglacial valleys beneath the ice sheet. Our analysis of the gravity data also allows us to infer the presence of thick (>500 m) sediments near the grounding line through much of the GIS, as well as variations in the density and/or thickness of the crust underlying the ice shelf.
Net Ecosystem Carbon Balance in a North Carolina, USA, Salt Marsh
Authors: Czapla K. M. , Anderson I. C. , Currin C. A.
Published: September 2020

Salt marshes have among the highest carbon (C) burial rates of any ecosystem and often rely on C accumulation to gain elevation and persist in locations with accelerating sea level rise. Net ecosystem carbon balance (NECB), the accumulation or loss of C resulting from vertical CO2 and CH4 gas fluxes, lateral C fluxes, and sediment C inputs, varies across salt marshes; thus, extrapolation of NECB to an entire marsh is challenging. Anthropogenic nitrogen (N) inputs to salt marshes impact NECB by influencing each component of NECB, but differences in the impacts of fertilization between edge and interior marsh must be considered when scaling up. NECB was estimated for the 0.5 km2 Spartina alterniflora marsh area of Freeman Creek, NC, under control and fertilized conditions at both interior and edge berm sites. Annual CO2 fluxes were nearly balanced at control sites, but fertilization significantly increased net CO2 emissions at edge sites. Lateral C export, modeled using respiration rates, represented a significant C loss that increased with fertilization in both edge and interior marsh. Sediment C input was a significant C source in the interior, nearly doubling with fertilization, but represented a small source on the edge. When extrapolating C exchanges to the entire marsh, including edge which comprised 17% of the marsh area, the marsh displayed net loss of C despite a net C gain in the interior. Fertilization increased net C loss fivefold. Extrapolation of NECB to whole marshes requires inclusion of C fluxes for both edge and interior marsh.
The Added Value of Different Data Types for Calibrating and Testing a Hydrologic Model in a Small Catchment
Authors: Széles B. , Parajka J. , Hogan P. , Silasari R. , Pavlin L. , Strauss P. , Blöschl G.
Published: September 2020

This study investigated the added value of different data for calibrating a runoff model for small basins. The analysis was performed in the 66 ha Hydrological Open Air Laboratory, in Austria. An Hydrologiska Byråns Vattenbalansavdelning (HBV) type, spatially lumped hydrologic model was parameterized following two approaches. First, the model was calibrated using only runoff data. Second, a step‐by‐step approach was followed, where the modules of the model (snow, soil moisture, and runoff generation) were calibrated using measurements of runoff and model state variables and output fluxes. These measurements comprised laser‐based measurements of precipitation, satellite and camera observations of snow, ultrasonic measurements of snow depth, eddy covariance measurements of evapotranspiration, time domain transmissometry‐based soil moisture measurements, time‐lapse photography of overland flow, and groundwater level measurements by piezometers. The two model parameterizations were evaluated on annual, seasonal, and daily time scales, in terms of how well they simulated snow, soil moisture, evapotranspiration, overland flow, storage change in the saturated zone, and runoff. Using the proposed step‐by‐step approach, the relative runoff volume errors in the calibration and validation periods were 0.00 and −0.01, the monthly Pearson correlation coefficients were 0.92 and 0.82, and the daily logarithmic Nash Sutcliffe efficiencies were 0.59 and 0.18, respectively. By using different sources of data besides runoff, the overall process consistency improved, compared to the case when only runoff was used for calibration. Soil moisture and evapotranspiration observations had the largest influence on simulated runoff, while the parameterization of the snow and runoff generation modules had a smaller influence.
Cusp and Mega Cusp Observations on a Mixed Sediment Beach
Authors: Matsumoto H. , Young A. P. , Guza R. T.
Published: September 2020

Frequent surveys using modern remote sensing technology enable observations of subaerial beach morphology and surface sediment type (sand vs. gravel/cobble) with unprecedented spatial and temporal resolution. Here we show weekly terrestrial mobile light detection and ranging (LiDAR) observations of cusps on a mixed sediment beach, consisting of sand and gravel/cobble, spanning ∼2 km alongshore. Surface gravel/cobble coverage varied from almost complete to none (e.g., all sand), over times ranging from weekly to seasonal, and with location. Cusp morphologies also varied in space and time. Cusps with 11–20 m alongshore wavelengths (L) primarily developed in winter and were composite with gravel‐cobble horns and sandy bays. Cusps with L between 21 and 40 m developed throughout the year and were either composite or entirely sandy. Previously not reported, composite mega cusps (L between 200 and 400 m) occurred in winter. Composite cusps, with L between 11 and 40 m, were clustered in gravel/cobble‐rich mega cusp bays and absent on the sandier mega cusp horns.
Have We Got Dust All Wrong?
Authors: Dimitropoulos Stav
Published: September 2020

Scientists are challenging conventional notions of how dust particles are aligned; “everything we’ve so far hypothesized about the impact of dust on the atmosphere might be misplaced.”
Scaling of Magnetic Reconnection With a Limited X‐Line Extent
Authors: Huang Kai , Liu Yi‐Hsin , Lu Quanming , Hesse Michael
Published: September 2020

Contrary to all the 2‐D models, where the reconnection x‐line extent is infinitely long, we study magnetic reconnection in the opposite limit. An internal x‐line asymmetry along the current direction develops because of the transport of reconnected magnetic flux by electrons beneath the ion kinetic scale, resulting in a suppression region identified in Liu et al. (2019, https://doi.org/10.1029/2019JA026539). In this letter, we incorporate the length scale of this suppression region ≃10di to quantitatively model the reduction of the reconnection rate and the maximum outflow speed observed in the short x‐line limit. The average reconnection rate drops because of the limited active region (where the current sheet thins down to the electron inertial scale) within an x‐line. The outflow speed reduction correlates with the decrease of the J × B force, that can be modeled by the phase shift between the J and B profiles, also as a consequence of the flux transport.
Mars Express Observations of Cold Plasma Structures in the Martian Magnetotail
Authors: Stergiopoulou K. , Andrews D. J. , Edberg N. J. T. , Halekas J. , Kopf A. , Lester M. , Opgenoorth H. J. , Sánchez‐Cano B.
Published: September 2020

We present observations from five Mars Express (MEX) orbits in September 2016 while the spacecraft passed through the Martian induced magnetotail at altitudes up to 3,500 km. On these orbits, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument was operated in Active Ionospheric Sounding (AIS) mode at much higher altitude than normal, acting as a local sounder and detecting cold plasma structures in this region. In this paper we combine MARSIS tail measurements with solar wind data from the Solar Wind Ion Analyzer (SWIA) instrument and the Magnetometer (MAG) from Mars Atmosphere and Volatile EvolutioN (MAVEN) in order to investigate possible factors affecting plasma transport from the dayside and through the terminator. MARSIS observed structured cold ionospheric plasma along its trajectory, at all altitudes and solar zenith angles (SZAs). Isolated regions of cold plasma were also observed on each orbit as the spacecraft crossed the terminator, even at high altitudes. We conclude that the variability of plasma seen in the tail results from a multifactorial transport process, the development of which cannot be attributed to a sole parameter influencing it, despite the availability of simultaneous high quality solar wind measurements.
Westward Plasma Drifts in the Nighttime Equatorial Ionosphere During Severe Magnetic Storms: A New Type of Penetration Electric Fields Caused by Subauroral Polarization Stream
Authors: Huang Chao‐Song
Published: September 2020

Penetration electric fields during geomagnetic storms have important effects on the equatorial ionospheric electrodynamics. Previous studies focus on the vertical ion drifts, corresponding to electric fields in the zonal direction, in the equatorial ionosphere. In this study, we analyze the characteristics of the zonal ion drifts in the equatorial region measured by the Defense Meteorological Satellite Program (DMSP) satellites during 10 severe magnetic storms with a minimum Dst < −200 nT in the solar maximum years of 2000–2003. It is found that the net change of the equatorial zonal ion drifts caused by magnetic storms is westward and can reach 200–300 m s−1in the evening sector and that the westward ion drifts remain in the same direction during both the storm main and recovery phases. The storm‐induced zonal ion drifts are highly correlated with the Dst index, and the correlation coefficient between the average zonal drift and the average Dst value during the 10 storms is 0.89. The magnitude of the storm‐induced westward ion drifts is approximately linearly proportional to the Dst index in the evening sector, and on average, a change of −100 nT in Dst causes a change of −52 m s−1in the zonal drift. The westward ion drifts caused by magnetic storms become small when Dst recovers to the range of −55 to −123 nT. A new mechanism is proposed to explain the generation of the westward plasma drifts in the nighttime equatorial ionosphere. This new mechanism is that the poleward electric fields associated with the subauroral polarization stream (SAPS) penetrate or extend to low latitudes, producing the westward plasma drifts in the equatorial region. The results of this study provide new insight into equatorial ionospheric electrodynamics during geomagnetic storms.
Electrical Conductivity of Ti‐Bearing Hydrous Olivine Aggregates at High Temperature and High Pressure
Authors: Dai Lidong , Karato Shun‐ichiro
Published: September 2020

We investigated the electrical conductivity of Ti‐H‐doped synthetic olivine aggregates at 4 GPa, 873–1273 K, and controlled oxygen fugacities. Under a given pressure and temperature, electrical conductivity depends on both hydrogen and Ti content, but these samples show different conductivity behavior from that observed in Ti‐poor sample such as San Carlos olivine. We found that when Ti content is comparable to or larger than hydrogen content, Ti has notable effects on electrical conductivity, but the effects of Ti is different between the H‐rich and the H‐poor regimes. In the H‐rich regime, electrical conductivity of olivine is weakly dependent on Ti content but has different sensitivity to water content than a Ti‐poor olivine. In contrast, in the H‐poor regime, electrical conductivity of Ti‐rich olivine is substantially higher than the conductivity of Ti‐poor olivine. As a consequence, the effect of hydrogen for the Ti‐rich synthetic olivine on electrical conductivity is smaller than for the Ti‐poor (natural) olivine for the modest H content expected in the asthenosphere, whereas in the H‐poor lithosphere Ti will enhance the electrical conductivity substantially. Possible models to explain these observations are proposed including the interaction of Ti‐related defects and H‐related defects as well as the charge transfer caused by the hopping conduction due to Ti3+ ⇔ Ti4+ under the H‐poor conditions. We conclude that the addition of Ti to olivine affects the behavior of H‐related defects, and therefore the applications of results from Ti‐rich olivine samples to the Ti‐poor real Earth need to be made with great care.
The 3‐D Structure of Mesoscale Eddies in the Lofoten Basin of the Norwegian Sea: A Composite Analysis From Altimetry and In Situ Data
Authors: Sandalyuk Nikita V. , Bosse Anthony , Belonenko Tatyana V.
Published: September 2020

In this research temperature and salinity profiles in eddy‐centered coordinates obtained from satellite altimetry (eddy data set distributed by Archiving, Validation and Interpretation of Satellite Oceanographic data) are combined to document the mean three‐dimensional structures of cyclonic (CEs) and anticyclonic (AEs) eddies in the Lofoten Basin. For eddies of both polarities, significant eddy‐induced anomalies are concentrated within the zero vorticity radius and vertically to the depth of ∼900–1,000 m. The thermohaline vertical structures of CEs and AEs differ in terms of salinity and temperature anomalies. Horizontal structure of the mesoscale eddies showed warmer and saltier anomalies for AEs from the southwest to the northeast side, as well as colder and less salty anomalies from their southeast side for the CEs. This reflects the main features of the basin‐scale temperature and salinity gradients, strongly affected by the Norwegian Atlantic Slope Current. Mean zonal eddy‐induced transport of volume, heat, and salt is generally westward, consistent with the key role played by eddies generated by the Norwegian Atlantic Slope Current. The obtained results highlight the significant role played by mesoscale eddies in the oceanic circulation of the Lofoten Basin, as well as on heat and salt budgets of a key region for air‐sea exchanges, water mass transformation, and climate.
Transport and Evolution of the East Reykjanes Ridge Current
Authors: Koman G. , Johns W. E. , Houk A.
Published: September 2020

This study of the first continuous multiyear observations of the East Reykjanes Ridge Current (ERRC) reveals a highly variable, mostly barotropic southwestward flow with a mean transport of 10–13 Sv. The ERRC effectively acts as a western boundary current in the Iceland Basin on the eastern flank of the Reykjanes Ridge. As part of the Overturning in the Subpolar North Atlantic Program (OSNAP), continuous measurements of the ERRC have been maintained for the first time using acoustic Doppler current profilers, current meters, and dynamic height moorings at six mooring sites near 58°N since 2014. Together with satellite altimetry and Argo profile and drift data, the mean transport, synoptic variability, water mass properties, and upstream and downstream pathways of the ERRC are examined. Results show that the ERRC forms in the northeastern Iceland Basin at the convergence of surface waters from the North Atlantic Current and deeper Icelandic Slope Water formed along the Iceland‐Faroe Ridge. The ERRC becomes denser as it cools and freshens along the northern and western topography of the Basin before retroflecting over the Reykjanes Ridge near 59°N into the Irminger Current. Analysis of the flow‐weighted density changes along the ERRC's path reveals that it is responsible for about one third of the net potential density change of waters circulating around the rim of the subpolar gyre.
Seasonality in the Response of East Asian Westerly Jet to the Mid‐Holocene Forcing
Authors: Wang Na , Jiang Dabang , Lang Xianmei
Published: September 2020

The East Asian westerly jet (EAWJ) features large seasonal variations in its intensity and position and exerts profound influences on local precipitation. In this study, we found the amplified seasonality of the EAWJ in response to the mid‐Holocene forcing. Compared with the preindustrial, the summer EAWJ significantly weakens by 20 ± 4% and shifts northward by 4 ± 2° during the mid‐Holocene, while the winter EAWJ slightly strengthens by less than 5%. Two different mechanisms are proposed to explain the significant summer weakening. From the perspective of stationary waves, the deficient precipitation over the tropical northwest Pacific produces the anomalous cyclonic circulations in the upper troposphere. The easterly winds north of the cyclone act to decelerate the EAWJ. In terms of transient processes, the mid‐Holocene reduced midlatitude meridional temperature gradient suppresses the synoptic‐scale disturbances through changes in the atmospheric baroclinicity. The subsequent decrease in kinetic energy transformation from transient eddies to the mean flow contributes to the weakening of the EAWJ. The reduction of the meridional temperature gradient is related to the subtropical cooling, which is possibly caused by the excessive monsoon rainfall and enhanced convection over East and South Asia. Both mechanisms involve the influence of low‐latitude precipitation on the midlatitude jet stream behavior, which deserves more attention in future studies of the jet stream dynamics.
Complex Interactions Between Large Igneous Province Emplacement and Global‐Temperature Changes During the Cenomanian‐Turonian Oceanic Anoxic Event (OAE 2)
Authors: Percival L. M. E. , van Helmond N. A. G. M. , Selby D. , Goderis S. , Claeys P.
Published: September 2020

Super greenhouse temperatures at the onset of the Cenomanian‐Turonian oceanic anoxic event (OAE 2) have been widely linked with large igneous province (LIP) volcanic activity. However, the extent to which volcanism influenced subsequent climate changes throughout OAE 2, such as global cooling during the Plenus Cold Event (PCE) early in the OAE, and the subsequent return to very warm conditions through the second part of the crisis remain less clear. Here, new osmium‐isotope (187Os/188Os) data are presented from the northeastern margin of the proto‐North Atlantic Ocean (ODP Leg 174AX Bass River, NJ, USA). The results are consistent with previously published OAE 2 records and are similarly interpreted as documenting LIP activity while further demonstrating the ability to use osmium‐isotope stratigraphy as a global chemostratigraphic marker in open‐ocean records. Correlations of 187Os/188Os and sea‐surface temperature trends at Bass River and other sites show that the earliest PCE cooling coincided with intense volcanism, but that LIP activity began to decline during or soon after the cold pulse. These temporal relationships support previous hypotheses that the PCE was regionally diachronous and likely caused by enhanced carbon sequestration via organic‐matter burial and silicate weathering, rather than a period of volcanic quiescence, while the persistently warm conditions later in OAE 2 were linked to reduced silicate weathering rather than sustained volcanism. These findings highlight the complex interactions between LIP emplacement and climate responses during OAE 2, reemphasizing the need for similar correlations between volcanism and paleotemperature proxy data for other major events in Earth's history.
Jurassic Salt Tectonics in the SW Sub‐Alpine Fold‐and‐Thrust Belt
Authors: Célini Naïm , Callot Jean‐Paul , Ringenbach Jean‐Claude , Graham Rodney
Published: September 2020

Evaporites play a major role in the evolution of an orogenic wedge, modifying the shape and the deformation kinematics inside the wedge. Salt tectonics can occur at various stages, but early salt activity can create a structural inheritance which compartmentalizes the building of the sedimentary succession and the mechanical architecture of the orogenic wedge. Sub‐Alpine fold‐and‐thrust belts commonly show evidence of inherited salt‐related structures, which were mostly described as having been initiated during the Liassic Tethyan rifting. However, even though a few authors tried to introduce salt tectonics as a major factor in the Alpine history, most of the interpretations underestimate the phenomenon. In this paper, we show that the Digne Nappe area presents many salt‐controlled structures within both the Digne and the Authon‐Valavoire thrust sheets. Salt activity began during the Hettangian and continued through the whole Jurassic. At a larger scale, our observations show alignments of salt‐controlled structures following NW–SE and NNE–SSW directions, as well as preferential locations at tectonic unit boundaries. Distribution of salt structures seems to follow a well‐defined pattern directly inherited from the rifting, and this strongly influences deformation of the sub‐Alpine domain.
3‐D Analog Modeling Constraints on Rifting in the Afar Region
Authors: Khalil Hany M. , Capitanio Fabio A. , Betts Peter G. , Cruden Alexander R.
Published: September 2020

Rifting in the Afar region is considered to be the only known example of the formation of an incipient divergent triple junction. Taking the Afar region as an example, we use three‐dimensional lithospheric‐scale laboratory experiments to constrain the factors controlling the structure and the tectonic evolution of the area. We systematically evaluate the role of different preexisting heterogeneities, such as those due to plume head impingement or inherited weak structures, and different kinematic boundary conditions, such as orthogonal versus rotational extension. The interaction between these inherited heterogeneities and the tested boundary conditions results in a range of complex rift geometries and structural features, such as rift segmentation and ridge jumps, which are comparable to those observed in the Afar region. At the plate scale, only under rotational extension, consecutive rift zones intersecting at high angles develop akin to the along‐axis segmentation in the Red Sea and the Gulf of Aden. Under orthogonal extension, the dominant rifting trend is perpendicular to the stretching direction. Preexisting weaknesses, including that due to a mantle plume, trigger different rifting styles and influence the geometry of large‐scale continental breakup. When compared to the Afar region, our results suggest that differing the degree of stretching, following the rotation of the Arabian plate since the Oligocene, led to the rifting in the Red Sea and the Gulf of Aden and likely did not cause the formation of the Main Ethiopian Rift.
Characterizing the Influence of Multiple Uncertainties on Predictions of Contaminant Discharge in Groundwater Within a Lagrangian Stochastic Formulation
Authors: Ciriello Valentina , de Barros Felipe P. J.
Published: September 2020

Assessing the risks associated with transport of contaminants in hydrogeological systems requires the characterization of multiple sources of uncertainty. This paper examines the impact of the uncertainty in the source zone mass release rate, aquifer recharge, and the spatial structure of the hydraulic conductivity on transport predictions. Through the use of the Lagrangian framework, we develop semianalytical solutions for the first two moments of the total solute discharge through a control plane while accounting for source zone release conditions and recharge. We employ global sensitivity analysis (GSA) to investigate how the predictive uncertainty of the mass discharge is affected by uncertainty in source zone mass release rate, recharge, and the variance of the log‐conductivity field. The semianalytical solutions are employed with the polynomial chaos expansion technique to perform a GSA. Our results reveal the relative influence of each source of uncertainty on the robustness of model predictions, which is critical for site managers to allocate resources and design mitigation strategies.
Coherent Streamflow Variability in Monsoon Asia Over the Past Eight Centuries—Links to Oceanic Drivers
Authors: Nguyen Hung T. T. , Turner Sean W. D. , Buckley Brendan M. , Galelli Stefano
Published: September 2020

The Monsoon Asia region is home to ten of the world's biggest rivers, supporting the lives of 1.7 billion people who rely on streamflow for water, energy, and food. Yet a synthesized understanding of multicentennial streamflow variability for this region is lacking. To fill this gap, we produce the first large scale streamflow reconstruction over Monsoon Asia (62 stations in 16 countries, 813 years of mean annual flow). In making this reconstruction, we develop a novel, automated, climate‐informed, and dynamic reconstruction framework that is skillful over most of the region. We show that streamflow in Monsoon Asia is spatially coherent, owing to common drivers from the Pacific, Indian, and Atlantic Oceans. We also show how these oceanic teleconnections change over space and time. By characterizing past and present hydroclimatic variability, we provide a platform for assessing the impact of future climatic changes and informing water management decisions.
Brca2 deficiency drives gastrointestinal tumor formation and is selectively inhibited by mitomycin C
Authors: Chen Xiaomin , Peng Fangfei , Ji Yan , Xiang Honggang , Wang Xiang , Liu Tingting , Wang Heng , Han Yumin , Wang Changxu , Zhang Yongfeng , Kong Xiangyin , Lang Jing-Yu
Published: September 2020

BRCA2 is crucial for repairing DNA double-strand breaks with high fidelity, and loss of BRCA2 increases the risks of developing breast and ovarian cancers. Herein, we show that BRCA2 is inactively mutated in 10% of gastric and 7% of colorectal adenocarcinomas, and that this inactivation is significantly correlated with microsatellite instability. Villin-driven Brca2 depletion promotes mouse gastrointestinal tumor formation when genome instability is increased. Whole-genome screening data showed that these BRCA2 monoallelic and biallelic mutant tumors were selectively inhibited by mitomycin C. Mechanistically, mitomycin C provoked double-strand breaks in cancer cells that often recruit wild-type BRCA2 for repair; the failure to repair double-strand breaks caused cell-cycle arrest at the S phase and p53-mediated cell apoptosis of BRCA2 monoallelic and biallelic mutant tumor cells. Our study unveils the role of BRCA2 loss in the development of gastrointestinal tumors and provides a potential therapeutic strategy to eliminate BRCA2 monoallelic and biallelic mutant tumors through mitomycin C.
Glutathione detection in human serum using gold nanoparticle decorated, monodisperse porous silica microspheres in the magnetic form
Authors: Gökçal Burcu , Hamaloğlu Kadriye Özlem , Kip Çiğdem , Güngör Selen Yağmur , Büber Esra , Tuncel Ali
Published: September 2020

A nanozyme for glutathione (GSH) detection in a broad concentration range was synthesized.
Novel keto–enol tautomerism in 1,3,5-trihydroxybenzene systems
Authors: Ruaysap Makabodee , Kennedy Stuart R. , Mayhan Collin M. , Kelley Steven P. , Kumari Harshita , Deakyne Carol A. , Atwood Jerry L.
Published: September 2020

We report a new synthesis of the water-soluble compound 1,3,5-trihydroxy-2,4,6-trimethylsulfonic acid (1), which exists in two tautomeric forms (60 : 40::enol%:keto%), and its lanthanide complexes. Relative tautomer stability is influenced by intramolecular H-bonding and competing implicit solvent effects.
Target identification of a macrocyclic hexaoxazole G-quadruplex ligand using post-target-binding visualization
Authors: Yasuda Mizuho , Ma Yue , Okabe Sachiko , Wakabayashi Yuki , Su Dongdong , Chang Young-Tae , Seimiya Hiroyuki , Tera Masayuki , Nagasawa Kazuo
Published: September 2020

Macrocyclic hexaoxazoles (6OTD) are G-quadruplex (G4) ligands. The azide-modified derivative L2H2-6OTD-Az shows cytotoxicity towards cancer cells and visualizes G4 in live cells together with BODIPY bearing a strained-alkyne (CO-1).
Optimization strategies of composite phase change materials for thermal energy storage, transfer, conversion and utilization
Authors: Chen Xiao , Gao Hongyi , Tang Zhaodi , Dong Wenjun , Li Ang , Wang Ge
Published: September 2020

Thermal energy harvesting technologies based on composite phase change materials (PCMs) are capable of harvesting tremendous amounts of thermal energy via isothermal phase transitions, thus showing enormous potential in the design of state-of-the-art renewable energy infrastructure.
Emerging investigator series: bacterial opportunistic pathogen gene markers in municipal drinking water are associated with distribution system and household plumbing characteristics
Authors: Haig Sarah-Jane , Kotlarz Nadine , Kalikin Linda M. , Chen Thomas , Guikema Seth , LiPuma John J. , Raskin Lutgarde
Published: September 2020

Municipally-treated drinking water (DW) is a potential source of exposure to bacterial opportunistic pathogens (OPs), which can cause infection in susceptible individuals.
Selectivity and bio-compatibility of self-assembled chiral flower-like and helical nanostructures
Authors: Wagalgave Sopan M. , Padghan Sachin D. , Al Kobaisi Mohammad , La Duong Duc , Bhamidipati Keerti , Puvvada Nagaprasad , Bhosale Rajesh S. , Bhosale Sidhanath V. , Bhosale Sheshanath V.
Published: September 2020

The molecular building block NDI–LCA was synthesized via substitution of NDA at the di-imide position with two lithiocholic acid moieties, resulted into chiral flower line and helical nanostructures.
α-Diimine nickel complexes bearing axially bulky terphenyl and equatorially bulky dibenzobarrelene groups: synthesis, characterization and olefin polymerization studies
Authors: Wang Xiaohua , Dong Bo , Yang Qi , Liu Heng , Zhang Chunyu , Zhang Xuequan
Published: September 2020

A new family of asymmetric α-diimine nickel complexes bearing axially and equatorially bulky groups were synthesized successfully. They exhibited high catalytic activities for ethylene polymerization and afforded ultra-high-molecular-weight elastomeric polyethylenes.
Interfacing a phosphate catalytic reaction with a microbial metabolism for the production of azaphilone alkaloids
Authors: Liu Lujie , Zheng Jiawei , Zhang Xuehong , Wang Zhilong
Published: September 2020

Exploring PO43− as a Brønsted acid catalyst, a biocompatible amination reaction was successfully interfaced with the Penicillium sp. metabolism to produce sclerotiorin alkaloids.
Reductive catalytic fractionation of pine wood: elucidating and quantifying the molecular structures in the lignin oil
Authors: Van Aelst K. , Van Sinay E. , Vangeel T. , Cooreman E. , Van den Bossche G. , Renders T. , Van Aelst J. , Van den Bosch S. , Sels B. F.
Published: September 2020

In-depth structural analysis of pine wood RCF lignin discloses new detailed insights into the RCF lignin oil's molecular structure.
In situ synthesis of coaxial CsPbX3@polymer (X = Cl, Br, I) fibers with significantly enhanced water stability
Authors: Liu Wenna , Fu Hui , Liao Hao , Liang Zhao , Ye Yumin , Zheng Jinju , Yang Weiyou
Published: September 2020

In situ synthesis of coaxial CsPbX3@polymer (X = Cl, Br, I) fibers with significantly enhanced water stability by one-step electrospinning method.
Compact wideband SIW cavity‐backed slot antenna using triple resonance and hybrid mode
Authors: Kang Le , Wang Mei , Zhang Ping , Zhou Jin Zhu
Published: September 2020

A compact and wideband slot antenna backed by a square substrate integrated waveguide (SIW) cavity is presented. By exciting the dual‐slotted SIW cavity with an offset coaxial feed, a transverse electric (TE)110 resonant mode along with two hybrid modes as combinations of TE110 and TE120 resonances can be generated within a close range. The triple resonances contribute to producing a wideband response while maintaining a compact antenna structure. An antenna prototype with a total size of 0.49λ 0 × 0.49λ 0 × 0.16λ 0 is manufactured and experimentally tested. Measures results show that an operating band of about 33.0% is obtained. Meanwhile, it also exhibits stable unidirectional patterns and moderate gains over the whole band.
200°C/5 MHz GaN‐based gate driver circuits with 1 nF/4.7 Ω RC load for high‐temperature high‐frequency all‐GaN IC applications
Authors: Xu Zhe , Zhou Yang , Xin Xiong , Wang Wenjie , Xie Wuze , Li Juntao
Published: September 2020

A GaN‐based gate driver circuits have been successfully designed and fabricated using a commercially available 6‐inch GaN‐on‐Si platform. The driver circuits consist of three‐stage direct‐coupled FET logic (DCFL) inverters featuring monolithically integrated depletion‐mode (D‐mode) and enhancement‐mode (E‐mode) high electron mobility transistors (HEMTs). At room temperature (RT), at a supply voltage of 4 V the single‐stage DCFL fabricated on the same die exhibits a large gate swing (3.84 V) and large noise margins (logic‐low noise margin (NML ) of 1.55 V and logic‐high noise margin (NMH ) of 2.18 V), both of which are desirable for all‐GaN IC applications. Meanwhile, the gate driver circuits were characterised up to 200°C on a PCB with a capacitance load of 1 nF in series with 4.7 Ω resistance to resemble the load condition. At 200°C, the gate driver circuits function well even at 5 MHz operation frequency. The turn on/off propagation delay and rise/fall time of the gate driver circuits are 5/40 and 22/18 ns, respectively. As far as the authors’ knowledge, this is the highest reported operation frequency for GaN‐based gate driver circuits under such high temperature, making it very promising for high‐temperature high‐frequency all‐GaN integrated circuit (IC) applications.
k ‐Sparse extreme learning machine
Authors: Raza N. , Tahir M. , Ali K.
Published: September 2020

Extreme learning machine (ELM) is a single layer feed‐forward neural network with advantages of fast training and good generalization properties. However, when the size of the hidden layer is increased, both of these advantages are lost as the redundant information may cause overfitting. Traditional way to deal with the issue is to introduce regularisation which promote sparsity but in the output layer weight matrix. In this Letter, we proposed the use of sparsity inside the output of the hidden layer such as to use it as the only non‐linearity in the hidden layer. In the proposed formulation, we use linear activation function inside the hidden layer and keep k highest activity‐bearing neurons as a measure of sparsity. Using the principal component analysis, we project the resulting output layer matrix onto a low‐dimensional space in order to further remove redundant and irrelevant information, and speed up the training process. In order to verify the feasibility and effectiveness of the proposed method, we test and compare it with a number of ELM variants using benchmark datasets. Compared with these methods, our results demonstrate that the proposed method achieves better accuracy performance consistently across many different benchmark datasets.
Sidelobe improvement of Golay set sequences by using SA for radar applications
Authors: Farnane K. , Minaoui K.
Published: September 2020

This study has been made to improve the detection capacity of radar using phase coded waveforms especially the Golay set sequence while keeping the sidelobe ambiguity function to the possible minimum. This Letter begins with a description of Golay complementary sets construction from a graph and a determination of the parameters on which they depend to be optimised after. Then, the simulated annealing (SA) algorithm has been proposed to deal with low ambiguity problem of the Golay set, due to its simplicity and also to its effectiveness to solve this kind of problem. Simulation results show that the optimisation with SA has impressively improved the sidelobe rejection of Golay set sequences with a gain of up to 20 dB.
Hardware prototype demonstration of a cognitive radar with sparse array antennas
Authors: Fu Rong , Mulleti Satish , Huang Tianyao , Liu Yimin , Eldar Yonina C.
Published: September 2020

As a typical signal processing problem, direction‐of‐arrival (DOA) estimation has been adapted to a wide range of applications in radar‐based systems. A high DOA resolution requires a large number of antenna elements which increases the overall cost. To minimise the cost, it is desirable to choose an optimum sub‐array from a full array. To enable cognition, the subarrays are selected based on the present target scenario. By using deep learning (DL) based techniques, the authors show a cognitive sparse array selection technique. By using hardware simulations, they demonstrate the applicability of the deep learning (DL)‐based sparse antenna selection network in direction‐of‐arrival (DOA) estimation problems. They show that the DL‐based sub‐arrays lead to a higher direction‐of‐arrival (DOA) estimation accuracy by 6 dB over random array selection.
Dual‐band filter based on one single circular patch resonator with highly improved bandwidths and compact size
Authors: Liu Shicheng , Wang Xuedao , Zhang Hanqian , Zhang Kezhuo , Ding Zeyu , Zhang Gang , Yang Jiquan
Published: September 2020

In this Letter, a new design of dual‐band patch filter is proposed with greatly improved bandwidth and miniaturised size based on one single modified circular patch resonator. In this design, a metallic via is introduced in the centre region of the patch to develop the modified resonant TM01 mode (TM′01 mode), while two types of slot perturbations are adopted to separate a pair of degenerate modes of TM11 (TM11A and TM11B ) and control another pair of degenerate modes of TM21 (TM21A and TM21B ), respectively. Thus, two passbands with one transmission zero (TZ) can be attained by elaborately exploring these resonant modes (the TM′01 and TM11A modes form up the lower passband while TM11B and TM11A modes constitute the upper passband, and TM21B mode is responsible for the TZ). For verification, one prototype is implemented. Results indicate that the novel dual‐band filter (centred at 3.7 and 5.3 GHz) exhibits not only relative compact size (0.36 λ g × 0.36 λ g ), but also much larger 3‐dB fractional bandwidths (27 and 13%), nice return loss (better than 21 dB) and insertion loss (better than 1.0 dB), compared with other reported patch filters.
Weakly supervised retinal vessel segmentation algorithm without groundtruth
Authors: Lu Zheng , Chen Dali , Xue Dingyu
Published: September 2020

In the current image processing field, medical image segmentation needs a lot of groundtruths, and the process of making these groundtruths is time‐consuming and laborious. Thus, a novel retinal vessel segmentation algorithm without groundtruth is proposed in this Letter. The hierarchical clustering algorithm is first used to binary classify vessel and non‐vessel pixels. Then classification results based on DRIVE databases are used as pseudo groundtruths to train the neural networks and transfer learning is considered for subsequent processing. Next the trained network is used as the feature extraction tool, by calculating and comparing the difference of image features between the target domain data (DRIVE database) and the source domain data (STARE, CHASE DB1, and HRF databases) extracted from the network. The data required for training is expanded based on semi‐supervised clustering in this image feature space, finally the deep neural network is further fine‐tuned. Experiments on the publicly available fundus image dataset DRIVE demonstrate that the proposed method outperforms many other state‐of‐the‐art weakly supervised and unsupervised methods.
29‐/35 GHz Dual‐band high‐gain phase shifter with hybrid π‐networks
Authors: Wei Dong , Ding Xuan , Yu Hai , Kuan Yen‐Cheng , Gu Qun Jane , Xu Zhiwei , Ma Shunli , Ren Junyan
Published: September 2020

This Letter presents a 29‐/35 GHz dual‐band high‐gain hybrid π‐network‐based phase shifter. The hybrid π‐network realised by combining electrical tuning through capacitors and magnetic tuning through transformers extends the phase shift range. Furthermore, the phase shift modules are inserted between the vertically stacking transistors to realise the embedded phase shifting with the minimum loss. The Gm‐stages offer the additional signal gain to offset attenuation from the passive phase shifter. This prototype, fabricated in a 28 nm CMOS process, demonstrates a 360° continuous phase shift range with a maximum gain of 22 dB at 35 GHz, and 240° continuous phase shift range with a maximum gain of 20 dB at 29 GHz. It consumes 26 mW power and 1.25 mm × 0.75 mm chip area.
Transmission power and altitude design for energy‐efficient mission completion of small‐size unmanned aerial vehicle
Authors: Umair M. , Joung J. , Cho Y.S.
Published: September 2020

Owing to the rapid and facile deployment of unmanned aerial vehicles (UAVs), the third‐generation partnership programme has recently shown considerable interest in UAVs for assisting current terrestrial base stations. Hence, the feasibility of using UAVs has been vigorously investigated for enhancing the performance of traditional ground‐based communications, e.g. coverage and quality‐of‐service enhancement under natural disaster or overwhelming data requirement conditions. Here, however, the energy‐efficient operation of the UAV is necessary to obtain the essential benefits. To strengthen the base of operation and management of UAVs in cellular systems, the authors consider in this Letter a single mission in which a small‐size UAV transmits a given data volume to a cell boundary user. They design the transmit power and altitude of the UAV to complete the mission with high‐energy efficiency. From the numerical results, it is verified that the UAV transmitting data with the designed transmit power at the designed altitude can complete the mission with near‐optimal, i.e. maximum, energy efficiency.
Different degradation mechanism by conduction region in AsTeGeSiN threshold switching device
Authors: Choi H.‐S.
Published: September 2020

AsTeGeSiN threshold switching devices, which have recently gained attention for their reliable operation, are investigated for the degradation mechanism under constant voltage stress (CVS). Threshold switching devices are essential for 3D stacking of high‐density memories. The degradation mechanism can be divided into two conduction regions, i.e. before and after the threshold voltage (V th ) by applying CVS. It is found that charge trapping, which can easily be recovered, is the main degradation mechanism in the low‐conduction region. This is because Poole–Frankel conduction by deep traps occurred in the low‐conduction region. However, trap generation may occur when going from deep traps to shallow traps, which is an important factor in the high‐conduction region stress voltage. Switching stress for different duty cycles in two conduction regions is also performed. Therefore, when operating an AsTeGeSiN threshold‐switching device as a selector, the read sequence is not a problem despite frequent usage. However, for the write sequence, reducing the number and duration of pulses helps extend the device's lifetime.
Pipelined extended‐counting for 3D‐stacked CMOS image sensors
Authors: Callens N. , Lefebvre J. , Gielen G.
Published: September 2020

A novel multi‐stage pipelined extended‐counting (EC) for 3D‐stacked CMOS image sensors is presented, which combines the benefits of a pipelined ADC, a first‐order ADC and the EC principle in order to simultaneously achieve a high resolution and a high frame rate for 3D‐stacked imagers. By assigning each stage of the pipeline to a sub‐column of pixels while choosing another input stage of the pipeline when a sub‐column has been read out, discontinuous rolling shutter artefacts like chopped images can be eliminated and frame rates up to 340 fps can be achieved for imagers with 8 K resolution.
Virtual array interpolation for coprime arrays: a signal reconstruction perspective
Authors: Chen Zhen , Fan Chongyi , Huang Xiaotao
Published: September 2020

Coprime arrays can highly increase degree‐of‐freedom by operating the second‐order virtual signal. However, the corresponding virtual array is discontiguous, and thus most existing direction‐of‐arrival estimation approaches fail to utilise all received information. To avoid performance loss, the authors intend to convert the discontiguous array into a contiguous one in this Letter and propose two virtual array interpolation algorithms for the coprime array from the perspective of signal reconstruction. By promoting the sparsity of the signal via simplified atomic norm minimisation and enhanced matrix completion, respectively, the two algorithms can effectively reconstruct the signal of the interpolated virtual array in a gridless manner. Simulation results are presented to demonstrate the performance advantage of the two proposed approaches.
Coherent integration algorithm for random pulse repetition interval radar based on iterative adaptive approach
Authors: Yu Wenchao , Su Weimin , Gu Hong , Yang Jianchao , Lu Xingyu
Published: September 2020

An iterative adaptive approach (IAA) based algorithm is presented to realise coherent integration for the random pulse repetition interval radar. The proposed method firstly removes the effect of Doppler ambiguity via phase compensation, and then accomplishes target focusing via conducting the azimuth IAA and range inverse fast Fourier transform. Theoretical analysis and numerical experiments have verified the effectiveness of the proposed method.