bluuebunny/crossref_metadata_2025 huggingface dataset:
Land cover dynamics and their driving factors in a protected floodplain ecosystem
Authors: Basumatary Himolin , Devi Haobam Suchitra , Borah Suranjana Bhaswati , Das Apurba Kumar
Published: February 2021

Floodplains are simultaneously the most productive and threatened ecosystems in the world, with land cover integrity compromised even in “protected” floodplains. Due to their rich biodiversity, monitoring of land cover and understanding the causative drivers becomes imperative in the protected floodplains. This work performs spatio‐temporal assessment of land cover changes and discovers the underlying processes in the largest protected floodplain of the Brahmaputra River (BR)—Kaziranga National Park (KNP). Remotely sensed images of 1988, 1998, 2008, and 2018 were analyzed using visual interpretation techniques coupled with class description keys in GIS platform along with ground‐based surveys. Results show a substantial area decline under Dense Forest (7.7%), Open Forest (10%), Waterlogged wetland (31.3%), and Marsh/Swamp (70.4%) land cover classes between 1988 and 2018. The considerable reduction in forests and wetlands is likely to impact the life support system of the park as they form the key habitats and food resources. Concurrently, dramatic area increase under riverine classes has led to huge landmass loss along the northern and eastern stretch. Though the BR and the local flood pulse are essential source of nutrient replenishment in the park, they also act as primary drivers of land cover alteration. Hydro‐geomorphic processes like bank erosion, high‐flood events, and siltation in association with vegetation succession and invasive species control the inter‐conversion of land cover classes in the KNP. The findings of this work provide an insight into the natural factors that instigate the land cover modification on large floodplains in general, and particularly in KNP.
Effects of cascade reservoirs on the transformation of nitrogen in pore water of sediments in the Lancang River
Authors: Zhao Ping , Wang Congfeng , Wang Xue , Yang Zhengjian , Liu Defu
Published: February 2021

In the mainstream of the Lancang River, eight cascade dams have been constructed. In order to find the effects of the cascade reservoirs on the transformation of nitrate (NO3‐N) and ammonium (NH4‐N) in pore water of sediments, a field survey was carried out both in the upper natural river reach (NRR) and cascade reservoirs reach (CRR) of the Lancang River from January 10 to 20, 2018. The results indicated that (1) in the NRR, NO3‐N concentrations in sediment pore water were higher than those in the CRR, whereas the total nitrogen (TN) and NH4‐N were significantly lower; the diffusion fluxes of NH4‐N from sediment to overlying water varied from −0.180 to 0.049 mg·(m2·d)‐1, and the diffusion fluxes of NO3‐N varied from 0.012 to 0.098 mg·(m2·d)‐1. (2) in the CRR, the NH4‐N concentrations in sediment pore water were much higher than those in the overlying water, but the NO3‐N concentrations in the overlying water were much higher; the diffusion fluxes of NH4‐N from the sediments to the overlying water varied from 0.161 to 1.561 mg·(m2·d)‐1, but the NO3‐N diffused downward from the overlying water to the sediments and the diffusion fluxes varied from −0.011 to −0.223 mg·(m2·d)‐1. It was concluded that the cascade reservoirs could increase the NH4‐N concentration and inversely decrease the NO3‐N concentration in the sediment pore water, which meant that the risk of the nitrogen release from the sediment in the cascade reservoirs was much higher than that in the natural river.
Reading From Multiple Documents: The Role of Text Availability and Question Type
Authors: Cerdán Raquel , Máñez Ignacio , Serrano-Mendizábal Marian
Published: February 2021

The current information society requires people to handle information from different sources, which entails specific skills beyond those needed to comprehend and use information from a single text. Given the relevance of becoming a competent reader in functional reading scenarios, it is crucial to examine how contextual‐, task‐, and individual‐related factors may influence multiple‐documents question‐answering activities, a key issue for assessment and instruction. In this study, we examined the influence of text availability and question type in students’ question‐answering performance and the moderator effect of students’ reading skill. Seventy secondary school students read three expository texts about a history topic. Next, they performed a concurrent question‐answering task consisting of a set of intra‐ and intertext questions they answered either with or without the texts available. Finally, participants performed a free‐recall task after a 24‐hour delay without access to the learning materials. Results showed higher performance scores in the intratext questions when the text was available than when it was not. However, the superiority of text availability disappeared in the delayed recall task. Additionally, skilled readers who had the texts available scored higher in the concurrent question‐answering task and, moreover, recalled more ideas in the recall task. These findings shed light on how contextual‐ (i.e., text availability), task‐ (i.e., question type), and student‐related (i.e., reading skill) factors may influence both adolescents’ question answering from multiple documents and their recall. The implications of these findings for the science of reading and the educational practice are discussed.
Effects of arbuscular mycorrhizal fungi symbiosis on microbial diversity and enzyme activities in the rhizosphere soil of Artemisia annua
Authors: Ma Junqing , Ma Yuan , Wei Zhuli , Wu Jiemin , Sun Chenyu , Yang Juan , Liu Lu , Liao Honglin , Chen Tingsu , Huang Jinghua
Published: February 2021

We explored the influence of symbiosis with arbuscular mycorrhizal fungi (AMF) on rhizosphere‐soil microecology and its relationship with the artemisinin content in Artemisia annua (Artemisia annua L.). Three treatment groups were established: A. annua in symbiosis with Funneliformis mosseae, A. annua in symbiosis with Glomus versiforme, and A. annua without AMF symbiosis as a blank control. The nutrient content, pH, microbial density, activity, diversity, and evenness as well as the urease, acid phosphatase, and sucrase activities of A. annua rhizosphere soil and the relative artemisinin content in A. annua in the absence and presence of AMF symbiosis were measured and analyzed at four stages: T1 (rosette stage, 30 d after transplanting), T2 (growth stage, 70 d after transplanting), T3 (mature stage, 90 d after transplanting), and T4 (harvest stage, 120 d after transplanting). The results showed that AMF symbiosis increased the activities of urease, acid phosphatase, and sucrase in the rhizosphere soil of A. annua; promoted the absorption and utilization of N and P; increased the relative content of artemisinin in the aboveground parts of A. annua; and improved the utilization of various carbon sources by rhizosphere microorganisms to some extent. In addition, AMF also improved the density, quantity. and diversity of microorganisms in the A. annua rhizosphere. Different AMF had different effects on A. annua. The results showed that AMF symbiosis improved the absorption and utilization of soil nutrients by A. annua and increased its relative artemisinin content. These results may provide a theoretical basis for the production of A. annua.
Neurotrophin-3 contributes to benefits of human embryonic stem cell-derived cardiovascular progenitor cells against reperfused myocardial infarction
Authors: Bi Wei , Wang Jinxi , Jiang Yun , Li Qiang , Wang Shihui , Liu Meilan , Liu Qiao , Li Fang , Paul Christian , Wang Yigang , Yang Huang-Tian
Published: February 2021

Acute myocardial infarction (MI) resulting from coronary ischemia is a major cause of disability and death worldwide. Transplantation of human embryonic stem cell (hESC)-derived cardiovascular progenitor cells (hCVPCs) promotes the healing of infarcted hearts by secreted factors. However, the hCVPC-secreted proteins contributing to cardiac repair remain largely unidentified. In this study, we investigated protective effects of neurotrophin (NT)-3 secreted from hCVPCs in hearts against myocardial ischemia/reperfusion (I/R) injury and explored the underlying mechanisms to determine the potential of using hCVPC products as a new therapeutic strategy. The implantation of hCVPCs into infarcted myocardium at the beginning of reperfusion following 1 hour of ischemia improved cardiac function and scar formation of mouse hearts. These beneficial effects were concomitant with reduced cardiomyocyte death and increased angiogenesis. Moreover, hCVPCs secreted a rich abundance of NT-3. The cardioreparative effect of hCVPCs in the I/R hearts was mimicked by human recombinant NT-3 (hNT-3) but canceled by NT-3 neutralizing antibody (NT-3-Ab). Furthermore, endogenous NT-3 was detected in mouse adult cardiomyocytes and its level was enhanced in I/R hearts. Adenovirus-mediated NT-3 knockdown exacerbated myocardial I/R injury. Mechanistically, hNT-3 and endogenous NT-3 inhibited I/R-induced cardiomyocyte apoptosis through activating the extracellular signal-regulated kinase (ERK) and reducing the Bim level, resulting in the cardioreparative effects of infarcted hearts together with their effects in the improvement of angiogenesis. These results demonstrate for the first time that NT-3 is a cardioprotective factor secreted by hCVPCs and exists in adult cardiomyocytes that reduces I/R-induced cardiomyocyte apoptosis via the ERK-Bim signaling pathway and promotes angiogenesis. As a cell product, NT-3 may represent as a noncell approach for the treatment of myocardial I/R injury.
Alternative education paths for pregnant girls and young mothers in Tanzania
Authors: Fute Antony Zakaria , Wan Xiulan
Published: February 2021

This paper aimed to elaborate the importance of investing in girls’ educating for socio‐economic development, by describing the Tanzania's Alternative Education Paths, following the ban of pregnant girls and young mothers in public regular schools. Qualitative design (document review) was used to collect and analyze data from different documents and official websites such as World Bank, UNESCO, UNICEF, and Ministries of Education. 3.6 million Primary and secondary aged children are out of school, and 5,500 girls drop out of school every year because of pregnancy in Tanzania. Open schools and Folk Development Colleges are not in good quality but opted as alternative paths for dropouts. Chinese adult education system and provision of sex education are few suggestions lamented in this article. Girls' education is essential and with the additional possible alternatives of ensuring pregnant girls’ right to education, the paper will help policymakers to think about the best option of ensuring pregnant girls’ and young mothers’ right to education.
Displaying survival of patient groups defined by covariate paths: Extensions of the Kaplan‐Meier estimator
Authors: Jay Melissa , Betensky Rebecca A.
Published: February 2021

Extensions of the Kaplan‐Meier estimator have been developed to illustrate the relationship between a time‐varying covariate of interest and survival. In particular, Snapinn et al and Xu et al developed estimators to display survival for patients who always have a certain value of a time‐varying covariate. These estimators properly handle time‐varying covariates, but their clinical interpretation is limited. It is of greater clinical interest to display survival for patients whose covariates lie along certain defined paths. In this article, we propose extensions of Snapinn et al and Xu et al's estimators, providing crude and covariate‐adjusted estimates of the survival function for patients defined by covariate paths. We also derive analytical variance estimators. We demonstrate the utility of these estimators with medical examples and a simulation study.
Diastereoselective Synthesis of Some Spiroheterocycles Using Base Reusable Heterogeneous Achiral Nanocatalyst in Aqueous Media
Authors: Ghanbari Zahra , Naeimi Hossein
Published: February 2021

This research is based on the synthesis of some new diastereoselective spiroheterocycles relying on the application of nanocatalysts designed from the functionalized magnetic nanoparticles with tetrazole. Also, the achievement of suitable product with stereopurity through base catalytic path. Water as a green solvent, NiFe2O4 magnetic nanoparticles as a separable and reusable catalyst and using simple and high efficiency method are some important advantages of this research.
Synthesis, Crystal Structure, Optical Properties and Stability of New Bismuth‐Based Organic‐Inorganic Compounds (C6H9N2)aBibXc (X=Cl, Br, I)
Authors: Hu Xinru , Wang Jilin , Mao Wenhui , Zheng Guoyuan , Mo Shuyi , Tian Nan , Zhou Bing , Long Fei , Zou Zhengguang
Published: February 2021

We report a series of high‐quality, low‐dimension, and bismuth‐based organic‐inorganic hybrid single crystals (C6H9N2)aBibXc (X=Cl, Br, I) fabricated via a simple hydrothermal method. The crystal structure, intermolecular interactions, morphology, chemical groups, bond characterization, and optical and thermal stability of the samples were detailed via X‐ray single crystal diffractomete, Hirshfeld surface analysis, field scanning electron microscopy (FSEM), fourier transform infrared spectrometer (FTIR), Raman, thermal gravimetric (TG), and Ultraviolet‐visible (UV‐vis) diffuse reflectance spectra. The results indicated that the (C6H9N2)2BiCl5 and (C6H9N2)2BiBr5 crystals displayed a monoclinic system with a P21/n space group at room temperature; the (C6H9N2)BiI4 crystal was P21/c. Meanwhile, the band gap could be continuously adjusted between 3.2 eV and 1.6 eV via the nature of halide ligands. The samples also have good thermal stability. The starting decomposition temperature of (C6H9N2)2BiCl5, (C6H9N2)2BiBr5, and (C6H9N2)BiI4 were 200 °C, 250 °C, and 300 °C, respectively. Therefore, this kind of organic‐inorganic hybrid compounds will be assumed to be a promising candidate for optical and electronic applications.
Effect of Humidity on the Electrical Properties of Poly (3, 4‐Ethylenedioxythiophene) – Poly (Styrenesulfonate) and its Carbon Nanotube Composites
Authors: Nanda Omita , Gupta Nidhi , Biradar Ashok M. , Saxena Kanchan
Published: February 2021

We report the effect of humidity on the electrical properties of different conductivity grades (low and high) of the polymer poly (3, 4‐ethylenedioxythiophene)‐poly (styrenesulfonate) (PEDOT : PSS) and their nanocomposites comprising of single walled carbon nanotubes (SWCNT). Polymer nanocomposites were prepared by using PEDOT : PSS with different weight ratio of chemically treated single walled carbon nanotubes (CT‐SWCNT). Humidity dependent change in resistance of thin films of pure and nanocomposites was measured and analyzed in detail. This basic study on the various conductivity grade PEDOT : PSS polymers and their SWCNT nanocomposites elucidate their response to humidity. It was found that the resistance of low and high conductivity grade pristine PEDOT : PSS films show opposite trends with respect to humidity. Interestingly these trends reverse in their nanocomposites containing CT‐SWCNT. The present study might find useful information for researchers working in the area of polymer nanocomposite based devices and applications.
Sulphonamide‐Containing Oxazoline Hybrids as New Class of Neuroprotective Agents and Lead Molecule as Autophagy Inducer
Authors: Kadaiahgari Chandra Sekhar , Saha Moumita , Ravuri Srinath , Nandigama Sandeep , Saha Krishna Das , Banerji Biswadip
Published: February 2021

Sulphonamide derived oxazoline hybrid compounds showed neuroprotective effects by inducing autophagy. In the present study, a series of sulphonamide containing oxazoline hybrids were synthesized and their neuroprotective efficacy in neuronal cell lines was explored. All the compounds showed moderate to good neuroprotection against adrenal medulla cell lines (PC 12). Compound 6 j had good neuroprotective activity against PC 12 cell lines showing increased expression of autophagy regulatory proteins (ATG7, LC 3B, p62, Beclin‐1) and anti‐apoptotic proteins (Bcl‐2) and also decreased expression of pro‐apoptotic proteins (Bax and Bad). This study demonstrated clearly that compound 6 j showed neuroprotective effect through the induction of autophagy and opens up new avenues for a new class of compounds as neuroprotective therapeutic agents.
2‐(Quinol‐8‐yl)pyrrole‐Boron Difluoride Complexes, Simple and Tractable Structures Exhibiting Red Emission
Authors: Nakano Takeo , Sumida Akifumi , Naka Kensuke
Published: February 2021

The boron difluoride complex bearing 2‐(quinol‐8‐yl)pyrrole as a ligand was synthesized as well as its derivatives bearing aromatic ring substituents at the α‐position of the pyrrole moiety. These compounds showed the potentiality of good red emission character in spite of their simple structures. In the present paper, the details of their optical properties are described and discussed based on computational studies and X‐ray structural analysis.
Deep Denitrogenation of Model Diesel Fuel Using Ni‐doped Mesoporous Carbon: Synthesis Route and Adsorption Study
Authors: Delkhosh Arvin Saffarian , Vahid Amir , Baniyaghoob Sahar , Saber‐Tehrani Mohammad , Mohammdi Roozbeh Malek
Published: February 2021

Nickel‐doped mesoporous carbon (MC) materials with 1, 4, and 7 wt. % nickel/MC, were synthesized and utilized for the elimination of indole, as representative of nitrogen‐containing compounds, from a model diesel fuel. Different instrumental techniques, including Fourier‐transform infrared (FT‐IR) spectroscopy, X‐Ray diffraction (XRD), N2 adsorption‐desorption analyses, field emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDXS), and transmission electron microscopy (TEM) were used to characterize the synthesized Ni‐doped mesoporous carbons. The XRD and N2 adsorption‐desorption results revealed that all the nickel‐modified materials had ordered hexagonal mesostructures. Response surface methodology coupled with a three‐variable, three‐level Box‐Behnken design (BBD) involving three center points and one response was employed for evaluating the influence of the three input parameters, namely temperature (A), contact time (B), and Ni content (C) on the adsorption yield. The optimum removal efficiency (96.5 %) was obtained at 42 °C, 1 wt. % of Ni loading, and 55 min contact time; also, possible adsorption mechanisms might be due to van der Waals interaction, H‐bonding, and π‐complexation. Additionally, the equilibrium data were analyzed using Langmuir, Freundlich, and Temkin isotherm models, and the Freundlich isotherm model showed a better fit to experimental data (R2 =0.9978).
Envisaging Future Energy Storage Materials for Supercapacitors: An Ensemble of Preliminary Attempts
Authors: Naskar Pappu , Chakraborty Priyanka , Kundu Debojyoti , Maiti Apurba , Biswas Biplab , Banerjee Anjan
Published: February 2021

Recent developments in supercapacitor technology in terms of materials and devices are reviewed herein. Beyond the conventional materials (i. e., carbonaceous matters, metallic compounds and conducting polymers), various multifunctional materials are reported in literature as future supercapacitive materials. A comprehensive account on such materials is lacking due to the diversified electrochemical characteristics of these materials. In this review, we bring all such non‐conventional multifunctional energy storage materials under a same umbrella for summarizing the recent advancements in supercapacitors. The envisaged multifunctional materials include metal‐organic‐frameworks (MOFs), covalent‐organic‐frameworks (COFs), heteroatom‐doped carbonaceous materials, biomass‐derived porous carbons, black phosphorous, mixed conductors, perovskite nanoparticles, polyoxometalates (POMs), redox active electrolytes, slurry materials for flow supercapacitors, thermal self‐charging materials, thermal self‐protective materials, piezoelectric materials and electrochromic materials. Inherent pros and cons of each class of material are discussed, and materials modifications towards the successful device fabrications are highlighted herewith. While the MOF‐based supercapacitors are drawing some attentions, other non‐conventional energy storage materials are truly in the nascent stage of developments. This review culminates with summary and proposed future directions for product developments. In brief, this article provides a holistic view regarding all non‐conventional multifunctional energy storage materials for future supercapacitor technology.
Do R&D investments in weak IPR countries destroy market value? The role of internal linkages
Authors: Belderbos René , Park Jinhyuck (Joseph) , Carree Martin
Published: February 2021

Research Summary

The growth of emerging economies has attracted R&D investments by multinational enterprises, but firms have struggled to protect their knowledge assets in these environments with weak intellectual property rights protection. Knowledge misappropriation may be reduced if firms use cross‐unit R&D teams to strengthen intra‐firm interdependencies and control. We examine the relationship between such internal linkage strategies, foreign R&D investments, and firm market valuation in a dynamic market valuation model for 117 leading multinational firms. While foreign R&D investments are positively associated with market value, IP risks in host countries reduce it. The latter effect disappears if firms have developed a pronounced internal linkage strategy in weak IP environments. Linkage strategy bears costs and, in the absence of IP risks, is negatively associated with market value.

Managerial Summary

The growing market potential of emerging economies has led to an increase in research & development (R&D) activities there by multinational firms. A known challenge to multinational R&D investors in these economies is the weak protection of intellectual property rights (IPR). Firms may seek to reduce the risks of local knowledge spillovers and IPR infringement by actively embedding internal linkages in the organization of R&D and relying on cross‐unit international R&D teams. We examine the consequences of such an internal linkage strategy for the performance effects of firms’ investments in weak IPR countries. Based on an analysis of 1763 cross‐border R&D investments by 117 leading multinational firms, we find that a firm's market value is negatively affected by new R&D investments in weak IPR countries, but that such a negative influence can indeed be mitigated if the firm's R&D organization embeds internal linkages. Consistent with this observation, we demonstrate that firms with an internal linkage strategy are able to limit local knowledge outflows in weak IPR environments. However, if an internal linkage strategy is applied in strong, rather than weak, IPR environments, it bears substantial costs and negatively affects performance.
Single‐Atom Catalysts Derived from Metal–Organic Frameworks for Electrochemical Applications
Authors: Zou Lianli , Wei Yong‐Sheng , Hou Chun‐Chao , Li Caixia , Xu Qiang
Published: February 2021

Single‐atom catalysts (SACs) have received tremendous attention due to their extraordinary catalytic performances. The synthesis of this kind of catalysts is highly desired and challenging. In the last few years, metal–organic frameworks (MOFs) have been demonstrated as a promising precursor for fabricating SACs. In this review, the progress and recent advances in the synthesis of MOF‐derived SACs and their electrochemical applications are summarized. First, the synthetic approaches based on MOFs and accessible characterization techniques for SACs as well as their advantages/disadvantages are discussed. Then, the electrochemical applications of these MOF‐derived SACs including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), CO2 reduction reaction (CO2RR), nitrogen reduction reaction (NRR), and other energy‐related reactions are reviewed. Finally, insights into the current challenges and future prospects of this field are briefly presented.
Progress of Exsolved Metal Nanoparticles on Oxides as High Performance (Electro)Catalysts for the Conversion of Small Molecules
Authors: Sun Xiang , Chen Huijun , Yin Yimei , Curnan Matthew T. , Han Jeong Woo , Chen Yan , Ma Zifeng
Published: February 2021

Utilizing electricity and heat from renewable energy to convert small molecules into value‐added chemicals through electro/thermal catalytic processes has enormous socioeconomic and environmental benefits. However, the lack of catalysts with high activity, good long‐term stability, and low cost strongly inhibits the practical implementation of these processes. Oxides with exsolved metal nanoparticles have recently been emerging as promising catalysts with outstanding activity and stability for the conversion of small molecules, which provides new possibilities for application of the processes. In this review, it starts with an introduction on the mechanism of exsolution, discussing representative exsolution materials, the impacts of intrinsic material properties and external environmental conditions on the exsolution behavior, and the driving forces for exsolution. The performances of exsolution materials in various reactions, such as alkane reforming reaction, carbon monoxide oxidation, carbon dioxide utilization, high temperature steam electrolysis, and low temperature electrocatalysis, are then summarized. Finally, the challenges and future perspectives for the development of exsolution materials as high‐performance catalysts are discussed.
In Situ Identifying the Dynamic Structure behind Activity of Atomically Dispersed Platinum Catalyst toward Hydrogen Evolution Reaction
Authors: Wang Jiali , Tan Hui‐Ying , Kuo Tsung‐Rong , Lin Sheng‐Chih , Hsu Chia‐Shuo , Zhu Yanping , Chu You‐Chiuan , Chen Tai Lung , Lee Jyh‐Fu , Chen Hao Ming
Published: February 2021

Single‐atom catalysts (SAs) with the maximum atom utilization and breakthrough activities toward hydrogen evolution reaction (HER) have attracted considerable research interests. Uncovering the nature of single‐atom metal centers under operating electrochemical condition is highly significant for improving their catalytic performance, yet is poorly understood in most studies. Herein, Pt single atoms anchoring on the nitrogen–carbon substrate (PtSA/N–C) as a model system are utilized to investigate the dynamic structure of Pt single‐atom centers during the HER process. Via in situ/operando synchrotron X‐ray absorption spectroscopy and X‐ray photoelectron spectroscopy, an intriguing structural reconstruction at atomic level is identified in the PtSA/N–C when it is subjected to the repetitive linear sweep voltammetry and cyclic voltammetry scanning. It demonstrates that the PtN bonding tends to be weakened under cathodic potentials, which induces some Pt single atoms to dynamically aggregate into forming small clusters during the HER reaction. More importantly, experimental evidence and/or indicator is offered to correlate the observed Tafel slope with the dynamic structure of Pt catalysts. This work provides an evident understanding of SAs under electrocatalytic process and offers informative insights into constructing efficient catalysts at atomic level for electrochemical water‐splitting system.
Graphene Sheets with Defined Dual Functionalities for the Strong SARS‐CoV‐2 Interactions
Authors: Donskyi Ievgen S. , Nie Chuanxiong , Ludwig Kai , Trimpert Jakob , Ahmed Rameez , Quaas Elisa , Achazi Katharina , Radnik Jörg , Adeli Mohsen , Haag Rainer , Osterrieder Klaus
Published: February 2021

Search of new strategies for the inhibition of respiratory viruses is one of the urgent health challenges worldwide, as most of the current therapeutic agents and treatments are inefficient. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has caused a pandemic and has taken lives of approximately two million people to date. Even though various vaccines are currently under development, virus, and especially its spike glycoprotein can mutate, which highlights a need for a broad‐spectrum inhibitor. In this work, inhibition of SARS‐CoV‐2 by graphene platforms with precise dual sulfate/alkyl functionalities is investigated. A series of graphene derivatives with different lengths of aliphatic chains is synthesized and is investigated for their ability to inhibit SARS‐CoV‐2 and feline coronavirus. Graphene derivatives with long alkyl chains (>C9) inhibit coronavirus replication by virtue of disrupting viral envelope. The ability of these graphene platforms to rupture viruses is visualized by atomic force microscopy and cryogenic electron microscopy. A large concentration window (10 to 100‐fold) where graphene platforms display strongly antiviral activity against native SARS‐CoV‐2 without significant toxicity against human cells is found. In this concentration range, the synthesized graphene platforms inhibit the infection of enveloped viruses efficiently, opening new therapeutic and metaphylactic avenues against SARS‐CoV‐2.
Tri‐Brominated Perovskite Film Management and Multiple‐Ionic Defect Passivation for Highly Efficient and Stable Solar Cells
Authors: Gong Zekun , He Benlin , Zhu Jingwei , Yao Xinpeng , Wang Sudong , Chen Haiyan , Duan Yanyan , Tang Qunwei
Published: February 2021

High‐quality perovskite films with low imperfections, high hole mobility, and matching energy levels play a crucial role in enhancing performance of perovskite solar cells (PSCs) without hole‐transporting materials (HTMs). Herein, it is demonstrated that the incorporation of a stable tetra‐bisphenol A (TBBPA) with diphenyl ring, polybromides, and hydroxyl groups additive into a perovskite film can simultaneously manipulate the crystal growth and passivate the defects through coordination interaction between the functional group (OH, Br) and the unsaturated halogen and metal ions (Br−, Cs+, and Pb2+), resulting in a reduced grain boundary as well as imperfection and increased hole mobility of the CsPbBr3 perovskite film. In addition, the valence band of a perovskite film with TBBPA additive is shifted upward to approach the work function of the carbon electrode, thereby improving the energy level alignment. Consequently, a significantly boosted charge extraction and reduced charge recombination of the carbon‐based HTM‐free CsPbBr3 PSCs is obtained after incorporating the TBBPA additive, yielding a maximum power conversion efficiency of up to 9.82% of the optimized device. Furthermore, the champion PSC without encapsulation displays a remarkable thermal and moisture stability after being kept in ambient air for 720 h at 85 °C and 85% relative humidity, respectively.
Lead‐Free Cs2SnI6 Perovskites for Optoelectronic Applications: Recent Developments and Perspectives
Authors: Ullah Saad , Wang Jiaming , Yang Peixin , Liu Linlin , khan Jansher , Yang Shi-E. , Xia Tianyu , Guo Haizhong , Chen Yongsheng
Published: February 2021

Since the booming research on perovskite solar cells (PSCs), organic–inorganic hybrid halide perovskites have triggered widespread research attention. This is seen in the unprecedented improvement of the power conversion efficiency (PCE) from an initial 3.8% to a remarkable 25.5%. Despite the fascinating improvement in PCEs, the toxicity of the detrimental lead element is a major limiting factor that hampers the commercialization prospect of lead‐based materials. Extensive efforts have been dedicated to the progress of lead‐free, stable, and ecofriendly perovskite materials for green‐energy applications. Recently, double‐halide Cs2SnI6 perovskite emerged as a star material due to its favorable optoelectronic properties, stable nature, and environmental friendliness. Thus, an in‐time review to recapitulate the recent advances of Cs2SnI6 is critical to provide viable theoretical and experimental strategies for synergic optimization of perovskite films. Herein, the theoretical and experimental understandings of the properties of Cs2SnI6 are summarized and the different fabrication methodologies and their influences on the properties of Cs2SnI6 are discussed. The application potential of Cs2SnI6 is further reviewed and the limiting factors that influence the performance of Cs2SnI6 devices are highlighted. In the end, prospective research directions to improve the optoelectronic properties are presented for developing efficient Cs2SnI6 devices.
Mass surveillance: A study of past practices and technologies to predict future directions
Authors: Underwood Ben , Saiedian Hossein
Published: February 2021

This paper aims to dispassionately examine the techniques and technologies of mass surveillance. We will study different approaches and technologies, including what each one surveils and how. We will also observe patterns and changes over time, and in doing so, we will seek to model the attributes exhibited by various methods. Finally, we will predict what next generation surveillance methods will look like, based on the attributes we have observed in past and current methods. Our key insights include: (a) mass surveillance methods share a number of common attributes, (2) we can analyze the expression of these attributes to predict future methods of mass surveillance, and (3) a likely next generation method will entail the monitoring of a communication platform with third‐party assistance to collect large amounts of private communication data for future analysis.
Adaptive Mesh Refinement Method for Speeding Up Numerical Simulation of Electroslag Remelting Process
Authors: Shi Hao , Qiao Haiyu , Li Tong , Shen Houfa
Published: February 2021

The electromagnetic field and the droplet profile in electroslag remelting (ESR) process play a pivotal role in the quality of final steel products. Numerical simulation remains a central challenge to investigate ESR process with a high‐efficiency and high‐accuracy method. Herein, a strategy embedding an adaptive mesh refinement (AMR) method in 3D‐coupled model is proposed to speed up the simulation of ESR process. The coupling phenomena of the electromagnetic field and the droplet profile are successfully predicted using this method. Compared with the results of uniform mesh, the deviation of AMR results is less than 2.2%, whereas the computational speed of the AMR method is 10 times faster. Moreover, the effects of two key parameters in AMR method, maximum refinement level and refinement interval, on computational accuracy and speed are studied. With the increasing maximum refinement level, the computational accuracy is improved obviously first and then slightly, but the computation time increases exponentially. The increasing refinement interval has little effect on the computational accuracy but can greatly save the time of mesh operation. The proposed strategy can promote the application of numerical simulation in industrial ESR process.
Improved Stress Corrosion Cracking Resistance of High‐Strength Low‐Alloy Steel in a Simulated Deep‐Sea Environment via Nb Microalloying
Authors: Zhao Qiyue , Fan Endian , Zhao Jinbin , Cui Qiaoqi , Huang Yunhua , Li Xiaogang
Published: February 2021

Microstructure observations, thermal desorption spectroscopy (TDS) tests, hydrogen permeation measurements, electrochemical tests, and slow strain rate tensile (SSRT) tests are conducted investigate the beneficial effect of Nb microalloying on the stress corrosion cracking (SCC) behavior of high‐strength low‐alloy (HSLA) steels in a simulated deep‐sea environment. The results show that the addition of Nb significantly decreases the SCC susceptibility of HSLA steel in a simulated deep‐sea environment, and the role of Nb is attributed to microstructure optimization and the strong hydrogen‐trap function of nanosized NbC precipitates with hydrogen activation energy up to 100.5 kJ mol−1. In the simulated deep‐sea environment, the SCC resistance of HSLA steel is enhanced by microstructure optimization and the hydrogen‐trap function via Nb microalloying, and both anodic dissolution (AD) and hydrogen embrittlement (HE) are weakened. Moreover, the improvement of SCC resistance of HSLA steel with a higher hydrogen concentration via Nb microalloying is more obvious, in which the decrease of hydrogen‐induced anodic dissolution (HIAD) and HE effects is more distinct, and the strong hydrogen‐trap effect of NbC precipitates is the predominant mechanism to improve SCC resistance.
Finite element analysis of rectangular RC beams strengthened with FRP laminates under pure torsion
Authors: Majed Muhanad M. , Tavakkolizadeh Mohammadreza , Allawi Abbas A.
Published: February 2021

Composite materials have attracted wide attention in strengthening of structural members. In this study, the behavior of rectangular reinforced concrete (RC) strengthened with fiber reinforced polymer (FRP) laminates under pure torsion was investigated numerically and validated by existing data from literature. Various practical strengthening configurations were considered and the efficiency of them was illustrated. Concrete damage plasticity constitutive model was used and required parameters was drawn. Good agreement in terms of torque–twist behaviors of RC beams strengthened with FRP laminates before and after cracking was found. Reasonable steel and FRP reinforcement responses as well as crack patterns were achieved and the failure modes of all the specimens were modeled correctly. A parametric study was carried out and parameter such as number of FRP plies, concrete compressive strength, and FRP strip orientations were considered. The results showed that the torsional capacity could improves by increasing the number of FRP plies and concrete compressive strength. Moreover, no significant change in the torsional capacity of RC beams when it was strengthened with a 45° or with a 90° FRP laminate was observed.
Organizational memory and institution theory: A postcolonial perspective
Authors: Lahiri Mohua , Bhandarker Asha , Behrens Alfredo
Published: February 2021

This article locates itself in the postcolonial experience where organizations were conceived and where they evolved imitating the concepts of the developed nations. As we found this to contradict existing theories of organizational memory, which look at it as an intra‐organizational concept, we undertook a case study to look at organizational memory in an Indian organization. Our study showed that organizational memory was often an imitation of existing practices and aspects of it were shared across organizations. It made us look at institutional theories of organizations that explored why organizations imitate and reproduce dominant practices of the industry. However, we also had evidence of the emergence of new organizational memory, driven by local and national contexts. This made us critically examine the homogeneity of institutionalism itself and look at how organizations from postcolonial societies need to grapple with what to retain, what to adapt, what to create, and the challenges they face in the emerging global economy.
Goreisan inhibits vascular endothelial cell migration and angiogenesis
Authors: Murakami Kazuhito , Horie Ichiro , Isohama Yoichiro
Published: February 2021

Aim

Goreisan (GRS) is a Japanese Kampo medicine, which has been clinically used to treat edema and headache. Recently, a clinical study indicated that GRS significantly suppresses the recurrence of chronic subdural hematoma (CSDH). In CSDH, leakage from immature blood vessels on the neomembrane is involved in the recurrence or exacerbation. Although several clinical reports have shown the effectiveness of GRS, the pharmacological properties and underlining mechanism of GRS are not clear. In this study, we examined the effect of GRS on the migration and proliferation of vascular endothelial cells via in vitro and in vivo experiments.

Method

Human umbilical vascular endothelial cells (HUVECs) were treated with vascular endothelial growth factor (VEGF) for 24 h, and migration ability, extracellular signal‐regulated kinase (ERK) phosphorylation level, and aquaporin‐1 (AQP1) expression level were measured. Matrigel containing VEGF was injected subcutaneously into the abdomen of C57BL mice (Matrigel plug assay). After oral administration of GRS for seven days, the effect on angiogenesis was examined by immunostaining.

Results

GRS inhibited VEGF‐induced migration in a dose‐dependent manner. GRS also inhibited VEGF‐induced phosphorylation of ERK, which is a major signaling molecule for the migration. In addition, GRS markedly decreased protein and mRNA expression of AQP1, which is another important regulator of endothelial cell migration. Finally, GRS inhibited angiogenesis, as revealed by in vivo Matrigel plug assay.

Conclusion

The findings indicated that GRS can suppress angiogenesis through inhibiting the migration of endothelial cells by downregulating ERK activation and aquaporin‐1 expression, leading to the preventive effect of GRS against CSDH recurrence.
Maternal plasma soluble neuropilin‐1 is downregulated in fetal growth restriction complicated by abnormal umbilical artery Doppler: a pilot study
Authors: Porter B. , Maulik D. , Babbar S. , Schrufer‐Poland T. , Allsworth J. , Ye S. Q. , Heruth D. P. , Lei T.
Published: February 2021

Objectives

Placental expression of neuropilin‐1 (NRP1), a proangiogenic member of the vascular endothelial growth factor receptor family involved in sprouting angiogenesis, was recently discovered to be downregulated in pregnancies with fetal growth restriction (FGR) and abnormal umbilical artery (UA) Doppler. Soluble NRP1 (sNRP1) is an antagonist to NRP1; however, little is known about its role in normal and FGR pregnancies. This study tested the hypotheses that, first, sNRP1 would be detectable in maternal circulation and, second, its concentration would be upregulated in FGR pregnancies compared to those with normal fetal growth and this would correlate with the severity of the disease as assessed by UA Doppler.

Methods

This was a prospective case–control pilot study of 40 singleton pregnancies (20 FGR cases and 20 uncomplicated controls) between 24 + 0 and 40 + 0 weeks' gestation followed in an academic perinatal center from January 2015 to May 2017. FGR was defined as an ultrasound‐estimated fetal weight < 10th percentile for gestational age. The control group was matched to the FGR group for maternal age and gestational age at assessment. Fetal ultrasound biometry and UA Doppler were performed using standard protocols. Maternal plasma sNRP1 measurements were performed using a commercially available ELISA.

Results

Contrary to the study hypothesis, maternal plasma sNRP1 levels were significantly decreased in FGR pregnancies as compared to those with normal fetal growth (137.4 ± 44.8 pg/mL vs 166.7 ± 36.9 pg/mL; P = 0.03). However, there was no significant difference in sNRP1 concentration between the control group and FGR pregnancies that had normal UA Doppler. Plasma sNRP1 was downregulated in FGR pregnancies with elevated UA systolic/diastolic ratio (P = 0.023) and those with UA absent or reversed end‐diastolic flow (P = 0.005) in comparison to FGR pregnancies with normal UA Doppler. This suggests that biometrically small fetuses without hemodynamic compromise are small‐for‐gestational age rather than FGR.

Conclusions

This study demonstrated a significant decrease in maternal plasma sNRP1 concentration in growth‐restricted pregnancies with fetoplacental circulatory compromise. These findings suggest a possible role of sNRP1 in modulating fetal growth and its potential as a biomarker for FGR. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.
Soil evaporation and its impact on salt accumulation in different landscapes under freeze–thaw conditions in an arid seasonal frozen region
Authors: Liu Sheng , Huang Quanzhong , Ren Dongyang , Xu Xu , Xiong Yunwu , Huang Guanhua
Published: February 2021

Soil evaporation and its associated processes are vital for agricultural production and ecosystems in seasonal frozen regions. However, soil evaporation and its impact on salt accumulation in different landscapes during freeze–thaw periods have not been well elucidated. In this study, field experiments were carried out to investigate soil evaporation and salt accumulation patterns in three typical landscapes—namely, cropland, woodland, and natural land—in an arid seasonal frozen region located in the upper reaches of the Yellow River basin from November 2018 to April 2019. The results indicated the highest soil evaporation occurred on natural land with a total amount of 148.5 mm during the freeze–thaw period from 2018 to 2019, whereas woodland had the smallest soil evaporation of 56.9 mm. Over 75% of soil evaporation occurred during the thawing stage for all three landscapes. The average daily evaporation was below 1 mm d–1 for the whole freeze–thaw period and was 0.1 mm d–1 for the stable freezing stage. Compared with humidity and wind speed, temperature and soil water content had a greater impact on soil evaporation. At the end of the thawing stage, the salt content in the topsoil (0–10 cm) layer increased significantly with an increasing rate of 70–225%. Salt concentrations in the topsoil were significantly and linearly related to the cumulative soil evaporation during the freeze–thaw period. The current research is expected to provide implications for water management and salinity control in the upper reaches of the Yellow River basin and in other arid regions with similar conditions.
Building semantic memory from embodied and distributional language experience
Authors: Davis Charles P. , Yee Eiling
Published: February 2021

Humans seamlessly make sense of a rapidly changing environment, using a seemingly limitless knowledgebase to recognize and adapt to most situations we encounter. This knowledgebase is called semantic memory. Embodied cognition theories suggest that we represent this knowledge through simulation: understanding the meaning of coffee entails reinstantiating the neural states involved in touching, smelling, seeing, and drinking coffee. Distributional semantic theories suggest that we are sensitive to statistical regularities in natural language, and that a cognitive mechanism picks up on these regularities and transforms them into usable semantic representations reflecting the contextual usage of language. These appear to present contrasting views on semantic memory, but do they? Recent years have seen a push toward combining these approaches under a common framework. These hybrid approaches augment our understanding of semantic memory in important ways, but current versions remain unsatisfactory in part because they treat sensory‐perceptual and distributional‐linguistic data as interacting but distinct types of data that must be combined. We synthesize several approaches which, taken together, suggest that linguistic and embodied experience should instead be considered as inseparably entangled: just as sensory and perceptual systems are reactivated to understand meaning, so are experience‐based representations endemic to linguistic processing; further, sensory‐perceptual experience is susceptible to the same distributional principles as language experience. This conclusion produces a characterization of semantic memory that accounts for the interdependencies between linguistic and embodied data that arise across multiple timescales, giving rise to concept representations that reflect our shared and unique experiences.

This article is categorized under:

Psychology > Language

Neuroscience > Cognition

Linguistics > Language in Mind and Brain