bluuebunny/crossref_metadata_2025 huggingface dataset:
The Contribution of Methane Photoproduction to the Oceanic Methane Paradox
Authors: Li Y. , Fichot C. G. , Geng L. , Scarratt M. G. , Xie H.
Published: June 2020

Although methanogenesis is considered a strictly anaerobic process, oxygen‐replete surface open‐ocean waters are usually supersaturated with methane (CH4), a phenomenon termed the oceanic methane paradox. Here, we report that abiotic methane photoproduction from chromophoric dissolved organic matter (CDOM) significantly contributes to this paradox. Methane photoproduction was observed during solar‐simulated irradiations of various waters collected along the land‐ocean continuum. Methane photoproduction rates decreased seaward, whereas its relative production efficiency and the methane‐to‐carbon‐monoxide (CO) photoproduction ratio (ΔCH4/ΔCO) both followed a reversed trend. Remote‐sensing modeling incorporating a ΔCH4/ΔCO–CDOM absorption relationship yielded an annual methane photoproduction of 118 Gg for the global open ocean, accounting for 20–60% of the open‐ocean methane efflux and being of comparable magnitude to the upper‐ocean methane microbial‐oxidation sink. The photodegradation of CDOM thus plays an important role in maintaining supersaturated methane concentrations in the oxygenated upper ocean and in sustaining oceanic methane emissions to the atmosphere.
Agile Adaptive Radar Sampling of Fast‐Evolving Atmospheric Phenomena Guided by Satellite Imagery and Surface Cameras
Authors: Kollias Pavlos , Luke Edward , Oue Mariko , Lamer Katia
Published: June 2020

The collection of high temporal resolution radar observations without compromising data quality requires adaptability and agility. So far, radar beam steering has been mostly guided by (i) expert judgment or (ii) stand‐alone automated identification and tracking algorithms operating on measurements collected by radar. The current study proposes a new paradigm, where external observations are used to optimize a radar's sampling strategy. Here the sampling strategy of a phased‐array radar and a polarimetric scanning cloud radar, two different yet uniquely complementary systems, is guided by an algorithm that uses observations from a geostationary satellite, a surface camera and the radars themselves to identify and track atmospheric phenomena. The tailored pointing and increase in sensitivity realized through this framework enables the steered radars to sample a diverse set of atmospheric phenomena such as shallow cumuli, lightning‐induced ice crystal orientation and a series of waterspouts.
Detailed Spatial Slip Distribution for Short‐Term Slow Slip Events Along the Nankai Subduction Zone, Southwest Japan
Authors: Kano Masayuki , Kato Aitaro
Published: June 2020

Many short‐term slow slip events (S‐SSEs) occur at the transition zone along the Nankai subduction zone, southwest Japan. Because crustal deformation due to a single S‐SSE is small, the source fault is often represented using a planar uniform single‐fault slip model, resulting in little constraint on the spatial heterogeneity in amounts of slip. To comprehensively investigate the detailed cumulative spatial distribution of S‐SSEs in the entire Nankai subduction zone, we adopted a stacking approach of Global Navigation Satellite System data by referencing low‐frequency earthquakes. We extracted the cumulative displacements due to 12, 11, and 14 S‐SSEs that occurred between 2004 and 2009 in eastern Shikoku, Kii, and Tokai; coherent displacements nearly opposite to the direction of plate subduction were obtained. The inverted slip indicated significant slip laterally elongated along the transition zone at ~30–35 km depth. Small slip patches were inferred in the shallow portions at ~15–20 km depth in eastern Shikoku and at ~10–15 km depth in Tokai, respectively. The shallow patch in eastern Shikoku was located on the downdip edge of the coseismic slip area of the 1946 Nankai earthquake, while the Tokai small slip was located on the shallower side of the anticipated source area of a large earthquake. Large slip patches of S‐SSEs tend to avoid the spatially dense low‐frequency earthquake areas; in major S‐SSE areas, the number of low‐frequency earthquakes is small. This spatial dependence of fault slip style within the transition zone provides new insights on the generation mechanism of slow earthquakes.
Meltwater‐Enhanced Nutrient Export From Greenland's Glacial Fjords: A Sensitivity Analysis
Authors: Oliver Hilde , Castelao Renato M. , Wang Chuning , Yager Patricia L.
Published: June 2020

As mass loss from the Greenland Ice Sheet accelerates, this modeling study considers how meltwater inputs to the ocean can impact marine ecosystems using a simplified fjord scenario. At marine‐terminating glaciers in Greenland fjords, meltwater can be delivered far below the sea surface, both as subglacial runoff (from atmosphere‐driven surface melt) and as basal melt (from ocean heat). Such delivery can result in buoyancy‐driven upwelling and the upward entrainment of nutrient‐rich deep water, which can support phytoplankton growth in fjord surface waters. For this study, we use an idealized fjord‐scale model to investigate which properties of glaciers and fjords govern the transport of buoyantly upwelled nutrients from fjords. We model the influence of fjord geometry, hydrology, wind, tides, and phytoplankton growth within the fjord on meltwater‐driven nutrient export to the ocean. We use the Regional Ocean Modeling System (ROMS) coupled to a buoyant plume model and a biogeochemical model to simulate physical and biogeochemical processes within an idealized tidewater glacial fjord. Results show that meltwater‐driven nutrient export increases with larger subglacial discharge rates and deeper grounding lines, features that are both likely to change with continued ice sheet melting. Nutrient export decreases with longer residence times, allowing greater biological drawdown. While the absence of a coastal current in the model setup prevents the downstream advection of exported nutrients, results suggest that shelf‐forced flows could influence nutrient residence time within fjords. This simplified model highlights key uncertainties requiring further observation to understand ecological impacts of Greenland mass loss.
Reducing Numerical Diffusion in Dynamical Coupling Between Atmosphere and Ocean in Community Earth System Model Version 1.2.1
Authors: Ma Jialiang , Xu Shiming , Wang Bin
Published: June 2020

Climate models contain atmospheric and oceanic components that are coupled together to simulate the thermodynamic and dynamic processes during air‐sea interactions. Community Earth System Model (CESM version 1.2.1) is a state‐of‐the‐art coupled model that is widely used and participates in Coupled Model Intercomparison Projects. Community Atmospheric Model (CAM), the atmospheric component of CESM, is based on the finite‐volume dynamic core, which utilizes staggered Arakawa‐D grids. However, the dynamics‐physics (D‐P) coupling in CAM causes the prognostic winds of the dynamic core be interpolated onto non‐staggered locations, which affects the wind structure for computing the air‐sea interaction and dynamical coupling. In this study we propose a new scheme that eliminates the extra interpolation during D‐P coupling for the atmosphere‐ocean interaction. We show that it improves the simulated climatology in key regions including eastern boundary upwelling regions and Southern Oceans. Compared with the default scheme, the new approach simulates strong surface wind near coast in eastern boundary upwelling regions. As a result, existing problems of the model, such as warm SST biases in these regions, are reduced. Meanwhile, for Southern Ocean, the prevailing westerlies are enhanced in new scheme, resulting in meridional sea ice transport. As a result, the overestimation of sea ice extent and negative bias in SST is reduced. This new scheme is generally applicable to coupled models with staggered dynamics‐physics, such as spectral‐element method based CAM.
Quantifying Fluid Retention Due to Natural Vegetation in a Forest Floodplain Analogue Using the Aggregated Dead Zone (ADZ) Dilution Approach
Authors: Carling Paul A. , Leyland Julian , Kleinhans Maarten G. , Besozzi Louison , Duranton Pierre , Trieu Hai , Teske Roy
Published: June 2020

Fluid retention and flow resistance due to natural vegetation remain poorly understood despite the importance of understanding these for flow routing and floodplain revegetation projects. Experiments were undertaken in a shallow earthen channel containing a natural cover of small trees, herbaceous plants, and leaf litter, which were sequentially removed and subjected to a range of flows. A dilution monitoring approach within the Aggregated Dead Zone framework was applied to a series of floodplain vegetated flows, yielding information on bulk flow parameters including tracer dispersion, fluid retention, and flow resistance at the reach scale. The primary response of flow to vegetation removal was a small increase in bulk velocity, with depth and wetted width decreasing only slightly. Reach mean travel time and the advective time delay decreased by about a factor of 2 with the removal of herbs, grass, and leaf litter, leaving only trees. Removing the trees, leaving a bare earthen channel, only slightly decreased travel times. Flow resistance and retention exhibited large values for low discharge and converged on a constant low value for relatively high discharges. It is concluded that flow resistance during low flow is higher than in a high flow with the same vegetation. Consequently, sparse vegetation has a prominent effect on hydraulic retention compared with an unvegetated channel at low discharges but this becomes negligible during high discharges as momentum increasingly dominates the flow. This outcome casts doubt on the efficacy of scrubby vegetation to impede higher‐velocity floodplain flows, showing need for field‐scale determination of integral floodplain resistance.
The Utility of Optical Satellite Winter Snow Depths for Initializing a Glacio‐Hydrological Model of a High‐Elevation, Andean Catchment
Authors: Shaw Thomas E. , Caro Alexis , Mendoza Pablo , Ayala Álvaro , Pellicciotti Francesca , Gascoin Simon , McPhee James
Published: June 2020

Information about end‐of‐winter spatial distribution of snow depth is important for seasonal forecasts of spring/summer streamflow in high‐mountain regions. Nevertheless, such information typically relies upon extrapolation from a sparse network of observations at low elevations. Here, we test the potential of high‐resolution snow depth data derived from optical stereophotogrammetry of Pléiades satellites for improving the representation of snow depth initial conditions (SDICs) in a glacio‐hydrological model and assess potential improvements in the skill of snowmelt and streamflow simulations in a high‐elevation Andean catchment. We calibrate model parameters controlling glacier mass balance and snow cover evolution using ground‐based and satellite observations, and consider the relative importance of accurate estimates of SDICs compared to model parameters and forcings. We find that Pléiades SDICs improve the simulation of snow‐covered area, glacier mass balance, and monthly streamflow compared to alternative SDICs based upon extrapolation of meteorological variables or statistical methods to estimate SDICs based upon topography. Model simulations are found to be sensitive to SDICs in the early spring (up to 48% variability in modeled streamflow compared to the best estimate model), and to temperature gradients in all months that control albedo and melt rates over a large elevation range (>2,400 m). As such, appropriately characterizing the distribution of total snow volume with elevation is important for reproducing total streamflow and the proportions of snowmelt. Therefore, optical stereo‐photogrammetry offers an advantage for obtaining SDICs that aid both the timing and magnitude of streamflow simulations, process representation (e.g., snow cover evolution) and has the potential for large spatial domains.
Rapid diversification of wild social groups driven by toxin-immunity loci on mobile genetic elements
Authors: Vassallo Christopher N , Troselj Vera , Weltzer Michael L , Wall Daniel
Published: June 2020

Many species form distinct social groups that provide fitness advantages to individuals. However, the evolutionary processes that generate new social groups are not well understood. Here we examined recently diverged natural isolates of the model social bacterium, Myxococcus xanthus, to probe the genetic mechanisms and evolutionary processes of kin discrimination that occurred naturally in soil. We show that social incompatibilities were formed from horizontal gene transfer of effectors belonging to three distinct polymorphic toxin systems; outer membrane exchange, type VI secretion and rearrangement hotspot systems. Strikingly, the unique toxin effectors and their respective immunity genes that are responsible for social incompatibilities reside on mobile genetic elements, which make up nearly all of the genotypic variation between isolates within clades. By disrupting these three toxin systems, we engineered social harmony between strains that were originally incompatible. In addition, a horizontal allele swap of a single kin recognition receptor changed social interactions and competition outcomes. Our results provide a case study for how horizontal gene transfer led to social diversification in a natural context. Finally, we show how genomic information of kin discriminatory loci can be used to predict social interactions.
Biotin provisioning by horizontally transferred genes from bacteria confers animal fitness benefits
Authors: Ren Fei-Rong , Sun Xiang , Wang Tian-Yu , Yao Ya-Lin , Huang Yan-Zhen , Zhang Xue , Luan Jun-Bo
Published: June 2020

Insect symbionts are widespread in nature and lateral gene transfer is prevalent in insect symbiosis. However, the function of horizontally transferred genes (HTGs) in insect symbiosis remains speculative, including the mechanism that enables insects to feed on plant phloem deficient in B vitamins. Previously, we found there is redundancy in biotin synthesis pathways from both whitefly Bemisia tabaci and symbiotic Hamiltonella due to the presence of whitefly HTGs. Here, we demonstrate that elimination of Hamiltonella decreased biotin levels but elevated the expression of horizontally transferred biotin genes in whiteflies. HTGs proteins exhibit specific expression patterns in specialized insect cells called bacteriocytes housing symbionts. Complementation with whitefly HTGs rescued E. coli biotin gene knockout mutants. Furthermore, silencing whitefly HTGs in Hamiltonella-infected whiteflies reduced biotin levels and hindered adult survival and fecundity, which was partially rescued by biotin supplementation. Each of horizontally transferred biotin genes are conserved in various laboratory cultures and species of whiteflies with geographically diverse distributions, which shares an evolutionary origin. We provide the first experimental evidence that biotin synthesized through acquired HTGs is important in whiteflies and may be as well in other animals. Our findings suggest that B vitamin provisioning in animal-microbe symbiosis frequently evolved from bacterial symbionts to animal hosts through horizontal gene transfer events. This study will also shed light on how the animal genomes evolve through functional transfer of genes with bacterial origin in the wider contexts of microbial ecology.
Signaling Inhibitors Accelerate the Conversion of mouse iPS Cells into Cancer Stem Cells in the Tumor Microenvironment
Authors: Du Juan , Xu Yanning , Sasada Saki , Oo Aung Ko Ko , Hassan Ghmkin , Mahmud Hafizah , Khayrani Apriliana Cahya , Alam Md Jahangir , Kumon Kazuki , Uesaki Ryo , Afify Said M. , Mansour Hager M. , Nair Neha , Zahra Maram H. , Seno Akimasa , Okada Nobuhiro , Chen Ling , Yan Ting , Seno Masaharu
Published: June 2020

Cancer stem cells (CSCs) are a class of cancer cells characterized by self-renewal, differentiation and tumorigenic potential. We previously established a model of CSCs by culturing mouse induced pluripotent stem cells (miPSCs) for four weeks in the presence of a conditioned medium (CM) of cancer cell lines, which functioned as the tumor microenvironment. Based on this methodology of developing CSCs from miPSCs, we assessed the risk of 110 non-mutagenic chemical compounds, most of which are known as inhibitors of cytoplasmic signaling pathways, as potential carcinogens. We treated miPSCs with each compound for one week in the presence of a CM of Lewis lung carcinoma (LLC) cells. However, one-week period was too short for the CM to convert miPSCs into CSCs. Consequently, PDO325901 (MEK inhibitor), CHIR99021 (GSK-3β inhibitor) and Dasatinib (Abl, Src and c-Kit inhibitor) were found to confer miPSCs with the CSC phenotype in one week. The tumor cells that survived exhibited stemness markers, spheroid formation and tumorigenesis in Balb/c nude mice. Hence, we concluded that the three signal inhibitors accelerated the conversion of miPSCs into CSCs. Similarly to our previous study, we found that the PI3K-Akt signaling pathway was upregulated in the CSCs. Herein, we focused on the expression of relative genes after the treatment with these three inhibitors. Our results demonstrated an increased expression of pik3ca, pik3cb, pik3r5 and pik3r1 genes indicating class IA PI3K as the responsible signaling pathway. Hence, AKT phosphorylation was found to be up-regulated in the obtained CSCs. Inhibition of Erk1/2, tyrosine kinase, and/or GSK-3β was implied to be involved in the enhancement of the PI3K-AKT signaling pathway in the undifferentiated cells, resulting in the sustained stemness, and subsequent conversion of miPSCs into CSCs in the tumor microenvironment.
Derivation of oocyte-like cells from putative embryonic stem cells and parthenogenetically activated into blastocysts in goat
Authors: Malik Hruda Nanda , Singhal Dinesh Kumar , Saini Sikander , Malakar Dhruba
Published: June 2020

Germ cells are responsible for the propagation of live animals from generation to generation, but to surprise, a steep increase in infertile problems among livestock poses great threat for economic development of human race. An alternative and robust approach is essential to combat these ailments. Here, we demonstrate that goat putative embryonic stem cells (ESCs) were successfullyin vitrodifferentiated into primordial germ cells and oocyte-like cells using bone morphogenetic protein-4 (BMP-4) and trans-retinoic acid (RA). Oocyte-like cells having distinct zonapellucida recruited adjacent somatic cells in differentiating culture to form cumulus-oocyte complexes (COCs). The putative COCs were found to express the zonapellucida specific (ZP1 and ZP2) and oocyte-specific markers. Primordial germ cell-specific markers VASA, DAZL, STELLA, and PUM1 were detected at protein and mRNA level. In addition to that, the surface architecture of these putative COCs was thoroughly visualized by the scanning electron microscope. The putative COCs were further parthenogenetically activated to develop into healthy morula, blastocysts and hatched blastocyst stage like embryos. Our findings may contribute to the fundamental understanding of mammalian germ cell biology and may provide clinical insights regarding infertility ailments.
Carbon nanoparticles induce endoplasmic reticulum stress around blood vessels with accumulation of misfolded proteins in the developing brain of offspring
Authors: Onoda Atsuto , Kawasaki Takayasu , Tsukiyama Koichi , Takeda Ken , Umezawa Masakazu
Published: June 2020

Nano-particulate air pollution threatens developing brains and is epidemiologically related to neurodegenerative diseases involving deposition of misfolded proteins. However, the mechanism underlying developmental neurotoxicity by nanoparticles remains unknown. Here, we report that maternal exposure to low doses of carbon black nanoparticle (CB-NP) induces endoplasmic reticulum (ER) stress associated with accumulation of misfolded proteins. Notably, offspring specifically showed high induction of ER stress in perivascular macrophages and reactive astrocytes only around brain blood vessels, along with accumulation of β-sheet-rich proteins regarded as misfolded proteins. Our results suggest that maternal CB-NP exposure induced ER stress in PVMs and reactive astrocytes around blood vessels in the brain of offspring in mice. The induction of ER stress accompanied by the perivascular accumulation of misfolded proteins is likely to be associated with perivascular abnormalities and neurodegeneration, and development of neurodegenerative diseases related to particulate air pollution.
Diagnostic Associations of Processing Speed in a Transdiagnostic, Pediatric Sample
Authors: Kramer Eliza , Koo Bonhwang , Restrepo Anita , Koyama Maki , Neuhaus Rebecca , Pugh Kenneth , Andreotti Charissa , Milham Michael
Published: June 2020

Introduction: The present study examines the relationships between processing speed (PS), mental health disorders, and learning disorders. Prior work has tended to explore relationships between PS deficits and specific diagnoses in isolation of one another. Here, we simultaneously investigated PS associations with five diagnoses (i.e., anxiety, autism, ADHD, depressive, specific learning) in a large-scale, transdiagnostic, community self-referred sample. Method. 843 children, ages 8–16 were included from the Healthy Brain Network (HBN) Biobank. Principal component analysis (PCA) was employed to create a composite measure of four PS tasks, referred to as PC1. Intraclass correlation coefficient (ICC) between the four PS measures, as well as PC1, were calculated to assess reliability. Results. ICCs were moderate between WISC-V tasks (0.663), and relatively modest between NIH Toolbox Pattern Comparison and other PS scales (0.14–0.27). Regression analyses revealed specific significant relationships between PS and reading and math disabilities, ADHD-inattentive presentation (ADHD-I), and ADHD-combined presentation (ADHD-C). After accounting for inattention, the present study did not find a significant relationship with Autism Spectrum Disorder. Discussion. Our examination of PS in a large, transdiagnostic sample suggested more specific associations with ADHD and learning disorders than the literature currently suggests. Implications for understanding how PS interacts with a highly heterogeneous childhood sample are discussed.
A new magnesium sheet alloy with high tensile properties and room-temperature formability
Authors: Shi Renhai , Miao Jiashi , Avey Thomas , Luo Alan A.
Published: June 2020

Lightweight sheet alloys with superior mechanical performance such as high strength, ductility and formability at room temperature (RT) are desirable for high volume automotive applications. However, ductility or formability of metallic alloys at RT are generally inversely related to strength, thereby making it difficult to optimize all three simultaneously. Here we design a new magnesium sheet alloy-ZAXME11100 (Mg-1.0Zn-1.0Al-0.5Ca-0.4Mn-0.2Ce, wt. pct.) via CALPHAD (CALculation of PHAse Diagram) modeling and experimental validation. This new sheet alloy offers an excellent RT formability with a high Index Erichsen (I.E.) value of 7.8 mm in a solution-treated condition (T4), due to its weak and split basal texture and fine grain structure. The new ZAXME 11100 alloy also shows a rapid age-hardening response during post-forming artificial aging treatment at 210 °C for 1 hour (T6), resulting in a significant increase of yield strength from 159 MPa (T4) to 270 MPa (T6). The excellent combination of T4 ductility (31%), T4 formability (7.8 mm) and T6 yield strength (270 MPa) in this new magnesium alloy is comparable to that of common 6xxx series aluminum sheet alloys. Thus, this new magnesium sheet alloy is highly attractive for sheet applications in automotive and other industries.
Study on oxidation activity of Ce–Mn–K composite oxides on diesel soot
Authors: Huang He , Zhang Xiao , Liu Junheng , Ye Song
Published: June 2020

As an effective method, diesel particulate filter (DPF) technology has a great contribution in reducing soot emissions from diesel engines. To achieve passive regeneration of DPF at low temperatures, K-doped Ce0.5Mn0.5O2 catalysts were synthesized using sol–gel method. The effect of K-doped catalysts-Kz–Ce0.5Mn0.5O2-on the oxidation of soot had been studied by thermogravimetric analysis, and the corresponding catalytic properties were evaluated based on X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), O2 temperature programmed desorption (O2-TPD) Raman spectroscopy (Raman), Brunauer–Emmett–Teller (BET) and Fourier-Transform-Infrared (FTIR).The results showed that K doping facilitated the oxidation of diesel particulate matter, which was indicated by the entire mass loss curve shifting to lower temperatures. K0.2–Ce0.5Mn0.5O2 showed the best performance among the series of K-doped catalysts. Compared with the findings for Ce0.5Mn0.5O2, the ignition temperature of soot oxidation (Ti) had been lowered by 28 ℃, and the maximum peak combustion temperature (Tm) of the dry soot decreased by 61 °C. Furthermore, compared with the Ce0.5Mn0.5O2-catalyzed reaction, K doping led to a lower activation energy and significantly improved pre-exponential factor. The minimum reaction activation energy of 27.46 kJ/mol was exhibited by K0.2–Ce0.5Mn0.5O2.
Cross-crop resistance of Spodoptera frugiperda selected on Bt maize to genetically-modified soybean expressing Cry1Ac and Cry1F proteins in Brazil
Authors: Machado Eduardo P. , dos S. Rodrigues Junior Gerson L. , Führ Fábio M. , Zago Stefan L. , Marques Luiz H. , Santos Antonio C. , Nowatzki Timothy , Dahmer Mark L. , Omoto Celso , Bernardi Oderlei
Published: June 2020

Spodoptera frugiperda is one of the main pests of maize and cotton in Brazil and has increased its occurrence on soybean. Field-evolved resistance of this species to Cry1 Bacillus thuringiensis (Bt) proteins expressed in maize has been characterized in Brazil, Argentina, Puerto Rico and southeastern U.S. Here, we conducted studies to evaluate the survival and development of S. frugiperda strains that are susceptible, selected for resistance to Bt-maize single (Cry1F) or pyramided (Cry1F/Cry1A.105/Cry2Ab2) events and F1 hybrids of the selected and susceptible strains (heterozygotes) on DAS-444Ø6-6 × DAS-81419-2 soybean with tolerance to 2,4-d, glyphosate and ammonium glufosinate herbicides (event DAS-444Ø6-6) and insect-resistant due to expression of Cry1Ac and Cry1F Bt proteins (event DAS-81419-2). Susceptible insects of S. frugiperda did not survive on Cry1Ac/Cry1F-soybean. However, homozygous-resistant and heterozygous insects were able to survive and emerge as fertile adults when fed on Cry1Ac/Cry1F-soybean, suggesting that the resistance is partially recessive. Life history studies revealed that homozygous-resistant insects had similar development, reproductive performance, net reproductive rate, intrinsic and finite rates of population increase on Cry1Ac/Cry1F-soybean and non-Bt soybean. In contrast, heterozygotes had their fertility life table parameters significantly reduced on Cry1Ac/Cry1F-soybean. Therefore, the selection of S. frugiperda for resistance to single and pyramided Bt maize can result in cross-crop resistance to DAS-444Ø6-6 × DAS-81419-2 soybean. The importance of these results to integrated pest management (IPM) and insect resistance management (IRM) programs is discussed.
Intravenous anti-VEGF agents with RGD peptide-targeted core cross-linked star (CCS) polymers modified with indocyanine green for imaging and treatment of laser-induced choroidal neovascularization
Authors: Cai Wenting , Chen Qijing , Shen Tianyi , Yang Qian , Hu Weinan , Zhao Peng , Yu Jing
Published: June 2020

S-PEG-ICG-RGD-RBZ NPs were synthesized to intravenously deliver anti-VEGF agents to choroidal neovascularization (CNV) areas for the treatment of CNV.
Asymmetric [N–I–N]+ halonium complexes
Authors: Ward Jas S. , Fiorini Giorgia , Frontera Antonio , Rissanen Kari
Published: June 2020

The first examples of unrestrained asymmetric silver(i) and halonium complexes have been prepared and characterised.
Green synthesis of air-stable tellurium nanowires via biomolecule-assisted hydrothermal for thermoelectrics
Authors: Liu Youfa , Jiang Qinglin , Zhang Jiang , Ding Wenjun , Xu Jingkun , Liu Peipei , Nie Guangming , Mao Haolai , Jiang Fengxing
Published: June 2020

Air-stable Te NWs with good electrical conductivity and the Seebeck effect have been obtained by a green method.
Hydrogel networks as underwater contact adhesives for different surfaces
Authors: Pan Feng , Ye Shaoxiong , Wang Ruixing , She Wei , Liu Jiaping , Sun ZhengMing , Zhang Wei
Published: June 2020

We have developed strong and durable hydrogel adhesives for underwater bonding.
Rational design of flower-like cobalt–manganese-sulfide nanosheets for high performance supercapacitor electrode materials
Authors: Hu Xiaomin , Liu Shunchang , Chen Yukai , Jiang Jibo , Cong Haishan , Tang Jiabin , Sun Yaoxin , Han Sheng , Lin Hualin
Published: June 2020

The design and development of composite materials with novel structures is one of the effective ways to enhance the electrochemical properties of supercapacitors.
Deprotection of a benzyl unit induces a 22π aromatic macrocycle of 3-oxypyripentaphyrin(0.1.1.1.0) with strong NIR absorption
Authors: Mori Daiki , Yoneda Tomoki , Suzuki Masaaki , Hoshino Tyuji , Neya Saburo
Published: June 2020

We report a deprotection-induced aromaticity switching from nonaromatic to a 22π aromatic macrocycle of 3-oxypyripentaphyrin(0.1.1.1.0) with strong NIR absorption.
Transient sliding of thin hydrogel films: the role of poroelasticity
Authors: Ciapa Lola , Delavoipière Jessica , Tran Yvette , Verneuil Emilie , Chateauminois Antoine
Published: June 2020

We propose a poroelastic description of the onset of sliding a glass probe for contacting an hydrogel film.
Cobalt sulfide nanoflakes grown on graphite foam for Na-ion batteries with ultrahigh initial coulombic efficiency
Authors: Wang Haisheng , Liu Jilei , Wang Huanhuan , Cai Xiaoyi , Ye Xinli , Zhang Lili , Chen Zhen , Shen Ze Xiang
Published: June 2020

Three underlying root causes for ultrahigh initial coulombic efficiency (99.4%) of Na-storage cobalt sulfide nanoarrays.
Asynchronous passive dynamic event‐triggered controller design for singular Markov jump systems with general transition rates under stochastic cyber‐attacks
Authors: Wang Haotian , Wang Yanqian , Zhuang Guangming , Lu Junwei
Published: June 2020

This study focuses on the issue of asynchronous passive controller design for singular Markov jump systems with general transition rates under stochastic cyber‐attacks. To maximise the utilisation of network resources by reducing unnecessary data transmissions, a dynamic event‐triggered rule is properly presented. Assuming that the system might be attacked by two kinds of stochastic cyber‐attacks, which are governed by two different functions. The asynchronous fact between the modes of the system and controller is described by the hidden Markov model. The criterion of stochastically admissible with a certain passive performance is established. In the light of a series of linear matrix inequalities, the asynchronous controller and dynamic event‐triggered rule are designed simultaneously. A numerical instance under different event‐triggered rules is offered to reveal the usefulness and effectiveness of the developed method.
Switching stabilising control of VSC‐HVDC transmission systems
Authors: Wang Tao , Xiang Weiming , Liu Yuwen
Published: June 2020

Power systems are a class of typical cyber‐physical systems with switching‐hybrid dynamics. With the innovation of power electronics technology and the implementation of power grid development strategy, the application of voltage source converter‐based high voltage direct current (VSC‐HVDC) transmission has been paid more and more attention. Firstly, the general small‐signal model of the VSC‐HVDC system is established, and its stability analysis is carried out by integrated modal analysis, participation factor analysis, and sensitivity analysis methods. It is clarified that the system controller parameters will have a significant impact on the stability of the VSC‐HVDC system. Then, based on the switching system theory, the stabilising switching law of the bidirectional converter is derived, which makes the system energy attenuate fastest, and the stabilising switching controller is designed according to the switching law. Last, the effectiveness of the controller is verified by simulation, and the superiority of the stabilising switching control strategy is proved from the theoretical and simulation aspects by comparison with the traditional current vector control strategy.
Reference‐free approach for mitigating human–machine conflicts in shared control of automated vehicles
Authors: Huang Chao , Lv Chen , Naghdy Fazel , Du Haiping
Published: June 2020

Shared control is a promising approach that can facilitate the mutual understanding and cooperative control between human and machine. In this study, a novel reference‐free framework for shared control of automated vehicles is proposed with the aim of mitigating conflicts between the human driver and the automatic system during their interactions. Position constraint and time to collision are deployed to prevent collision and guarantee stability by limiting the yaw rate and sideslip angle of the vehicle. The design of the shared controller is formulated as a model predictive control problem. It determines vehicle state based on the current driver command and implements control actions only if the vehicle state induced by the human driver violates the pre‐defined constraints. The system models, safety constraints and the proposed shared controller are then integrated. The algorithm is validated through computer simulation under two different driving scenarios. The simulation results show that the proposed reference‐free approach can offer the human driver more degrees of freedom during shared control, effectively mitigating human–machine conflicts, compared to the previous work. In addition, the algorithm ensures the safety and stability of the system under risky driving conditions, validating its feasibility and effectiveness.
Three‐dimensional finite‐element analysis multiphysics modelling of electromagnetic Joule heating in carbon fibre composites
Authors: Khan Jameel B. , Smith Alexander C. , Tuohy Paul M. , Gresil Matthieu , Soutis Constantinos
Published: June 2020

This study investigates the possibility of electromagnetic heating of carbon fibre composites (CFCs) to the resin curing temperature, utilising Joule heating, with the main potential application being the on‐site and in‐situ repair of damaged CFCs. The study describes the energy conversion from the supplied AC electrical current to the power generated and hence, heat produced in a CFC. This is investigated through the development of three‐dimensional (3D) finite‐element multiphysics models using a homogenous representation approach, which can represent single‐ and multi‐layer CFC lay‐ups. An experimental test‐rig is used to validate the 3D finite‐element models for both unidirectional and quasi‐isotropic CFCs. Both the numerical simulations and experimental results are in good agreement. The presented results show that electromagnetic induced Joule heating can be used to achieve resin curing temperatures in CFCs for potential applications such as in‐situ repair.
Advanced framework for highly secure and cloud‐based storage of colour images
Authors: Chidambaram Nithya , Raj Pethuru , Thenmozhi Karruppuswamy , Amirtharajan Rengarajan
Published: June 2020

The evergrowing virtualised information technology infrastructure is powered by cloud‐centric technology around the world. Cloud‐based multimedia storage has become an essential aspect for users and business behemoths. However, as per a survey of Norton, around 3800 breaches have been publicly disclosed with 4.1 billion numbers of records exposed in 2019, which is a 54% rise when compared to 2018. So the data security is a widely quoted barrier for cloud storage. Ciphering the confidential images before transmission and subsequent storage in cloud database needs critical attention for techno‐specific applications. In image encryption, chaos‐based keys can do better confusion, but the diffusion process using XOR is vulnerable to chosen plain text attack. The proposed colour image encryption scheme innately uses Deoxyribo Nucleic Acid coding that blends well with chaotic cryptosystem for an efficient statistical shift. The ciphered images are stored in authenticated and authorised cloud storage facilities. The experimentation is carried out with the help of Amazon Web Services storage instances. The proposed image encryption scheme offers a strong resistance towards the brute force, occlusion, statistical and differential attacks and yields near‐zero correlation and good entropy.
Implementation of output impedance in single‐phase inverters with repetitive control and droop control
Authors: Astrada Juan , De Angelo Cristian
Published: June 2020

A strategy for the implementation of the output impedance in single‐phase inverters connected in parallel with droop control for uninterruptible power supply applications is proposed in this study. The proposal allows the load current to be distributed in proportion to the power capacity of the inverters connected in parallel, by establishing the magnitude and phase of the output impedance at the fundamental frequency and its harmonics, when the voltage control is performed through odd harmonic repetitive controllers. This is accomplished through the design of an output impedance profile based on the transfer function of a second‐order high‐pass filter and a virtual impedance loop. The proposal achieves a correct operation of the droop control strategy and the proper sharing of the harmonics of the non‐linear load current between the inverters connected in parallel, obtaining reduced values of individual harmonic content and harmonic distortion in the output voltage with reduced processing requirements. The validity of the proposal is verified through a 2 kVA experimental prototype, considering the requirements of the international quality standards IEC62040‐3 and IEC61000‐2‐2, in terms of output voltage regulation, individual harmonic content, and harmonic distortion for inverters operating both in islanded‐mode and in parallel.
Improved harmonic injection pulse‐width modulation variable frequency triangular carrier scheme for multilevel inverters
Authors: Orfi Yeganeh Mohammad Sadegh , Sarvi Mohammad , Blaabjerg Frede , Davari Pooya
Published: June 2020

This study proposes an optimised controllable pulse‐width modulation (PWM) scheme suitable for multilevel inverters. Seeing the need for improving the output voltage characteristics such as total harmonic distortion, low‐order harmonic and distortion factor, an improved harmonic injection PWM variable frequency triangular carrier modulation technique is employed for off‐line mode. For this purpose, the carrier signal frequencies at each level (carrier‐based), and also amplitudes and orders of the harmonic‐injected signal (reference‐based) are considered as controllable parameters. The proposed technique benefits are operating with considerably fewer numbers of the pulses per cycle, low switching losses, and improvement in the output voltage characteristics. However, selective harmonic elimination and optimal switching angles are the most common modulation techniques, but they employ only one angle as a control parameter at each level of the output waveform. Hence, the modulation scheme can consider more angles at each level as controllable parameters by applying multi‐objective particle swarm optimisation and non‐dominated sorting genetic algorithm II (NSGA‐II). Simulations are conducted in 5‐, 7‐ and 9‐level inverter. Finally, the effectiveness of the studies is validated by obtaining experimental results on a single‐phase 1 kW 7‐level inverter prototype.
Synthetic inertial control of wind farm with BESS based on model predictive control
Authors: Bao Weiyu , Wu Qiuwei , Ding Lei , Huang Sheng , Teng Fei , Terzija Vladimir
Published: June 2020

Wind farms (WFs) can provide controlled inertia through synthetic inertial control (SIC) to support system frequency recovery after disturbances. This study proposes a model predictive control (MPC)‐based SIC for a WF consisting of wind turbines (WTs) and a battery storage energy system (BESS). In the proposed MPC‐SIC, the active power output of the WTs and BESS during the SIC are optimally coordinated in order to avoid over‐deceleration of the WTs' rotor, and minimise the loss of extracted wind energy during the SIC and degradation cost of the BESS. The IEEE 39‐bus system with a WF consisting of 100 WTs and a BESS is used to validate the performance of the proposed MPC‐SIC. Case studies show that, compared with the conventional SIC, the minimum rotor speed among all WTs with MPC‐SIC can be improved by 0.08–0.11 p.u., the loss of captured wind energy of WF with MPC‐SIC can be reduced by 12–64% and the degradation cost of the BESS with MPC‐SIC can be reduced by 72–83%. The results proves that with the proposed MPC‐SIC, the WF can avoid the over‐deceleration of the WTs' rotor and reduce the operation cost of the WF by improving the efficiency of wind energy usage and lifetime of the BESS.
Modelling and comparison analysis of grid‐connected DFIG‐based wind farm in weak grid
Authors: Yan Cai , Yao Wei , Wen Jianfeng , Fang Jiakun , Ai Xiaomeng , Wen Jinyu
Published: June 2020

This study proposes a generic method for modelling and comparison analysis of grid‐connected double‐fed induction generator (DFIG)‐based wind farms in a weak grid. A detailed model of DFIG in a weak grid is established and used as a benchmark. Specifically, the detailed model consists of the mechanical part, generator part, rotor side converter, and phase‐locked loop (PLL). Two simplified models of grid‐connected DFIG‐based wind farms in a weak grid are compared with the detailed model to investigate the mechanism of sub‐synchronous oscillation (SSO) as well as the influential factors through linear system analysis. The first simplified model ignores shafting dynamics, stator flux dynamics, and PLL dynamics. The same assumptions are used in the latter, except that PLL dynamics are considered. Time‐domain simulation and eigenvalue analysis are used to verify the accuracy of the simplified models. The block diagrams of the linearised system are derived based on the proposed model, and the oscillation mechanism is explained by linear system analysis. Through eigenvalue analysis and the root locus method, the influences of the parameters of the DFIG and its controllers on the system stability are identified and analysed.
Impact of resources distribution on high‐frequency behaviour of photovoltaic systems
Authors: Ghaderi Mohammad Hassan , Rashidirad Nasim , Hamzeh Mohsen
Published: June 2020

In this study, the distribution effect of grid‐connected inverters in photovoltaic (PV) plants is analysed. In fact, the interaction dynamics between different arrangements of distributed PV inverters and the grid are thoroughly compared. To this aim, the total power of all arrangements of distributed inverters is considered constant, which is called fixed‐power arrangements in this work. Accordingly, this study first develops the model of grid‐connected current‐controlled inverters (CCIs). Then, by applying the impedance‐based criterion, the effect of CCIs distribution on their stability is evaluated. Despite the fact that each CCI model is obtained based on the same stability margins, different distributed arrangements of CCIs have different interaction dynamics with the grid. From the frequency‐domain analysis, it is found that the distribution effect of CCIs can greatly affect the high‐frequency (HF) behaviour of their output admittances, and consequently improves their interaction dynamics; hence, one of the factors which can also play an important role in HF behaviour is distribution effect of CCIs in a PV plant. The simulation studies of several distributed arrangements of CCIs as well as a centralised CCI confirm the validity of the performed analysis.
Voltage violation in four‐wire distribution networks integrated with rooftop PV systems
Authors: Nour Ahmed M.M. , Helal Ahmed A. , El‐Saadawi Magdi M. , Hatata Ahmed Y.
Published: June 2020

Integration of rooftop photovoltaic (PV) systems in a three‐phase four‐wire distribution network cause voltage‐violations namely voltage‐rise and voltage unbalance. This study investigates the factors that affect both the voltage‐rise and voltage unbalance in low voltage distribution network integrated with the rooftop PV systems. The concerning factors are classified into active factors such as; loads active powers, PV active powers, and bus reactive powers, and passive factors such as; numbers of feeder buses and neutral‐grounded resistances. The study also determines the factors conditions at which the highest values of both voltage‐rise and voltage unbalance occurred. Moreover, the most and least significant effects of individual factors on both voltage‐rise and voltage unbalance are studied. The studied system is simulated and implemented in MATLAB software environment and the feeder loads are modelled based on Back–Forward Sweep method. The simulation results identify that the conditions of the worst voltage‐rise and voltage unbalance cases depend on the collective influence of the studied factors.
Multi‐objective control and operation of grid‐connected small hydro‐solar PV‐battery energy storage‐based distributed generation
Authors: Chandran Vineet P. , Kewat Seema , Singh Bhim
Published: June 2020

This work deals with the implementation, control and operation of a reconfigurable small hydro‐solar photovoltaic (PV)‐battery energy storage (BES)‐based distributed generation system (DGS) working in isolated mode (IM) and grid connected mode (GCM). The DGS consists of a hydro generation‐based on a PMSG integrated with a PV array supported by the BES. It operates in an IM during the grid outage and when the grid is available, it synchronizes and operates in GCM. A frequency adaptive comb filter‐frequency locked loop (FLL)‐based control is adopted to estimate errorless phase angles of the hydro generator and grid voltages for quick and accurate grid synchronization. A third‐order band pass filter‐based control technique is used to extract fundamental component of load currents and determine switching pulses to VSC. The overall multi‐objective control is used to maintain voltage and frequency of the system at the point of common coupling during IM and GCM. The power quality of grid and generator currents are maintained at non‐linear loads. The modified perturb and observe‐based control technique is used to extract maximum power from the PV array and it provides drift‐free operation during the change in insolation with de‐rating capability to protect the BES from overcharging in IM.