bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and properties of chitosan/organic‐modified attapulgite composite proton exchange membranes for fuel cell applications
Authors: Hu Fuqiang , Zhong Fei , Wen Sheng , Zheng Genwen , Gong Chunli , Qin Caiqin , Liu Hai 
Published: February 2020

AbstractThe chitosan (CS) matrix‐based composite proton exchange membranes (CS/QATP) were prepared by the incorporation of organic‐modified attapulgite (QATP) into CS, through an organic‐inorganic composite synthesis method. The QATP was obtained by the modification with silane coupling agent (octadecyldimethyl [3‐trimethoxysilylpropyl] ammonium chloride). The morphology, crystallinity, thermal and mechanical property, dimensional stability, and proton conductivity of CS/QATP composite membranes were investigated. The compatibility and dispersibility of QATP in CS matrix were significantly improved with enhanced interfacial interaction. The dimensional and thermal stability of the CS/QATP composite membranes were improved compared with pure CS film, owing to good dispersion and lower water uptake. Especially, the composite membrane with 2 wt% QATP (CS/QATP‐2) exhibits the highest mechanical strength and proton conductivity, which is much higher than pure CS film. These results indicated that CS/QATP composite membranes have a great potential for proton exchange membranes applications.
Cinnamic acid derivatives from welsh onion (Allium fistulosum) and their antibacterial and cytotoxic activities
Authors: Zolfaghari Behzad , Yazdiniapour Zeinab , Sadeghi Masoud , Akbari Mahtab , Troiano Raffaele , Lanzotti Virginia 
Published: February 2020

AbstractIntroductionCinnamic acids are a class of compounds based on phenyl propanoid backbone (C6‐C3) isolated from plants and microorganisms, exhibiting interesting biological activities.ObjectiveTo characterise cinnamic acids through the phytochemical study of welsh onion, Allium fistulosum, and to evaluate their antibacterial and cytotoxic properties.Material and methodsThe phytochemical study of A. fistulosum was performed through chromatographic techniques, including reversed phase medium‐pressure liquid chromatography (MPLC) and high‐pressure liquid chromatography (HPLC). Preliminary analysis of crude chromatographic fractions from the organic extracts was carried out by proton nuclear magnetic resonance (1H‐NMR) in order to prioritise the study of those having phenyl propanoid skeleton. The structural identification of the isolated compounds was performed through analysis of spectroscopic data, mainly one‐dimensional (1D) and two‐dimensional (2D) NMR. The antibacterial activity was assessed against gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacteria while the cytotoxic property was evaluated on breast cancer cell line (MCF‐7).ResultsThe 1H‐NMR study of crude fractions and application of a straightforward method to purify the phenyl propanoid compounds by reversed phase MPLC and HPLC, allowed the effortless isolation of several cinnamic acids, including two new rare phenolic imidates (1 and 2). The use of an entirely NMR approach for structural elucidation of the isolated metabolites allowed the isolated material to be kept for further pharmacological tests.ConclusionThese results corroborate the importance of the use of 1D and 2D NMR to the identification of new phenyl propanoids, potential lead compounds against bacteria and cancer cells.
Dynamic management needs for long‐lived, sporadically recruiting plant species in human‐dominated landscapes
Authors: Schweiger Andreas H. , Irl Severin D. H. , Svenning Jens‐Christian , Higgins Steven I. 
Published: February 2020

Societal Impact StatementLong‐lived, iconic plant species like the baobab, welwitschia, the saguaro cactus or the dragon's blood tree are perceived to be everlasting landscape features due to their pronounced longevity. However, these species are exceptional because new reproductive generations of these plants are infrequently incorporated into existing populations. A strong mismatch exists between the timescale at which these species provide services to society and ecosystems, and the timescale at which their reproductive stages and population development occurs. Here, we draw attention to these mismatches and their relevance for nature conservation and restoration. We argue that more dynamic management programs are necessary to preserve these iconic species for future generations.
Summary
Plants inhabiting variable environments have to adapt their physiology or demography to maintain fitness and, thus, long‐term population viability. Demographic storage through long‐lived seeds, juveniles, or adults help to overcome periods where unfavorable environmental conditions preclude successful recruitment into reproductive stages. Such storage components can foster long‐term population viability of sporadic recruiters, defined here as species with infrequent recruitment caused by a sporadic release from otherwise prevailing resource limitation. However, the beneficial effect of environmental variation reaches a limit when the species' physiological limits are exceeded or the demographic storage components are not sufficient to overcome periods of unfavorable environmental conditions. This can threaten species' long‐term population viability in an increasingly variable, human‐dominated world. At the same time, long‐lived, sporadically recruiting species provide numerous cultural, socio‐economic, and ecological services by being part of local myths and beliefs, or by providing habitat, food, wood, fiber, cosmetic, or medical products. In this contribution, we seek to raise awareness of what we call the ‘syndrome of long‐lived sporadic recruiters’ and the relevance of this syndrome for nature conservation and restoration. We outline key demographic features and highlight the main environmental threats for these plants, exemplified for a set of globally distributed charismatic plant species. We propose that fostering the long‐term population viability of long‐lived, sporadically recruiting plants will require the adaptive implementation of a dynamic management scheme where management actions, monitoring objectives, public outreach and research on the key demographic features of the species are coordinated.
Dynamical systems theory sheds new light on compound climate extremes in Europe and Eastern North America
Authors: De Luca P. , Messori G. , Pons F. M. E. , Faranda D. 
Published: February 2020

AbstractWe propose a novel approach to the study of compound extremes, grounded in dynamical systems theory. Specifically, we present the co‐recurrence ratio (α), which elucidates the dependence structure between variables by quantifying their joint recurrences. This approach is applied to daily climate extremes, derived from the ERA‐Interim reanalysis over the 1979–2018 period. The analysis focuses on concurrent (i.e., same‐day) wet (total precipitation) and windy (10 m wind gusts) extremes in Europe and concurrent cold (2 m temperature) extremes in Eastern North America and wet extremes in Europe. Results for wet and windy extremes in Europe, which we use as a test‐bed for our methodology, show that α peaks during boreal winter. High α values correspond to wet and windy extremes in northwestern Europe, and to large‐scale conditions resembling the positive phase of the North Atlantic Oscillation (NAO). This confirms earlier findings which link the positive NAO to a heightened frequency of extratropical cyclones impacting northwestern Europe. For the Eastern North America–Europe case, α extremes once again reflect concurrent climate extremes – in this case cold extremes over North America and wet extremes over Europe. Our analysis provides detailed spatial information on regional hotspots for these compound extreme occurrences, and encapsulates information on their spatial footprint which is typically not included in a conventional co‐occurrence analysis. We conclude that α successfully characterises compound extremes by reflecting the evolution of the associated meteorological maps. This approach is entirely general, and may be applied to different types of compound extremes and geographical regions.
Impacts of riverine sand mining on freshwater ecosystems: A review of the scientific evidence and guidance for future research
Authors: Koehnken Lois , Rintoul Max S. , Goichot Marc , Tickner David , Loftus Anne‐Claire , Acreman Mike C. 
Published: February 2020

AbstractSand mining (used here as a generic term that includes mining of any riverine aggregates regardless of particle size) is a global activity that is receiving increasing media attention due to perceived negative environmental and social impacts. As calls grow for stronger regulation of mining, there is a need to understand the scientific evidence to support effective management. This paper summarizes the results of a structured literature review addressing the question, “What evidence is there of impacts of sand mining on ecosystem structure, process, and biodiversity in rivers, floodplains, and estuaries?” The review found that most investigations have focused on temperate rivers where sand mining occurred historically but has now ceased. Channel incision was the most common physical impact identified; other physical responses, including habitat disturbance, alteration of riparian zones, and changes to downstream sediment transport, were highly variable and dependant on river characteristics. Ecosystem attributes affected included macroinvertebrate drift, fish movements, species abundance and community structures, and food web dynamics. Studies often inferred impacts on populations, but supporting data were scarce. Limited evidence suggests that rivers can sustain extraction if volumes are within the natural sediment load variability. Significantly, the countries and rivers for which there is science‐based evidence related to sand mining are not those where extensive sand mining is currently reported. The lack of scientific and systematic studies of sand mining in these countries prevents accurate quantification of mined volumes or the type, extent, and magnitude of any impacts. Additional research into how sand mining is affecting ecosystem services, impacting biodiversity and particularly threatened species, and how mining impacts interact with other activities or threats is urgently required.
Truth, success, and faith: Novice teachers’ perceptions of what's at risk in responsive teaching in science
Authors: Robertson Amy D. , Atkins Elliott Leslie J. 
Published: February 2020

AbstractResponsive teaching—or teaching that builds from the “seeds of science” in student thinking—is depicted in STEM education literature as both important and challenging. U.S. science education reform has been calling for teachers to enact instruction that attends to and takes up the substance of students’ STEM ideas; however, responsive teaching represents a substantial shift from the current state of affairs in most U.S. classrooms, where content is often presented authoritatively as facts, definitions, and algorithms, with little consideration of student thinking. Drawing on language from literature about sense‐making, this paper identifies some of the “vexation points” that novice science teachers face as they consider implementing responsive teaching practices in science—that is, what doesn't make sense, to teachers, about this instructional approach. In particular, we show that novice teachers express moral concerns about responsive teaching; themes in their written reflections suggest that they perceive responsive teaching to put truth, success, and faith at risk. We argue that though these concerns originally seem distinct from the institutional constraints to responsive teaching posed by the literature, teachers’ concerns about truth, success, and faith are in fact mutually reinforced by and reinforcing of external constraints. We use this connection to pose implications for research and teacher education.
Properties of Ultraviolet‐Shielding Composite Film Prepared from Cellulose Acetate with Eu(III) Complex
Authors: Zhang Yaping , Luo Bin , Sun Yong 
Published: February 2020

AbstractThe ultraviolet shielding composite films were prepared from cellulose acetate (CA) modified by grafting rare earth complexes Eu(MAA)3phen‐APS (MMA: Methacrylic Acid, APS: (3‐Aminopropyl)trimethoxysilane). The composite films possessed high optical transmittance and exhibited excellent ultraviolet (UV) absorption property. It exhibited bright red emission centered at 615 nm under UV excitation. The thermal analysis showed that the stability of the composite film is similar to that of pure CA. However, the glass transition temperature gradually disappeared with the increasing amount of Eu(MAA)3phen‐APS (Eu(III)‐complex) owing to the crosslinking reaction. The morphology analysis showed that the Eu(III)‐complex microdomains dispersedly was filled in the matrix of CA and a good interfacial adhesion was achieved. The size of the Eu(III)‐complex formed in the CA matrix is the main factor to effect the transparency of composite films.
Efficient Epimerization of Glucose to Mannose over Molybdenum‐Based Catalyst in Aqueous Media
Authors: Hu Hong , Liu Shaoru , Zhang Weizi , An Jiahuan , Xia Haian 
Published: February 2020

AbstractHerein, the high activity and selectivity of activated carbon‐supported molybdenum oxide catalysts (Mo/AC) in the epimerization of glucose to mannose is described. The catalysts afforded near‐equilibrium glucose conversion (29.2 %) and selectivity (94.5 %) toward mannose in the epimerization of glucose. The catalysts were characterized by X‐ray diffraction, UV‐Vis diffuse reflectance spectroscopy, and X‐ray photoelectron spectroscopy. It was found that the Mo/AC catalysts were mainly composed of highly dispersed MoO2 and MoO3 species. Compared to the soluble MoO3 catalyst, Mo/AC showed higher stability and better catalytic performances in the epimerization of glucose to mannose. Further, the deactivation of Mo/AC catalysts was attributed to the leaching of molybdenum oxides. Isotope labeling experiments revealed that the deuterium atom at the C‐1 position of mannose is formed by glucose‐D2 epimerization.
A Highly Active, Readily Synthesized and Easily Separated Graphene Oxide (GO)/Polyethersulfone (PES) Catalytic Membrane for Biodiesel Production
Authors: Tian Fengyu , Xu Baiqing , Li Yingjie , Deng Jie , Zhang Honglei , Peng Ruichao 
Published: February 2020

AbstractHeterogeneous acidic catalysts offer many advantages such as lower corrosion, easier separation and lower production cost compared with homogeneous sulfuric acid. Graphene oxide (GO) containing trace amount of oxygen‐containing functional groups have been demonstrated to be effective carbon‐based solid acid catalyst. However, GO are difficult to be recovered from liquid reaction system for further utilization. Graphene oxide/Polyethersulfone (PES) catalytic membranes were prepared and employed as heterogeneous acid catalysts in the esterification of oleic acid with methanol for biodiesel production. The membrane was annealed at different temperatures to promote the catalytic activity and reusability. As predicted, the OA conversion increased greatly with the increase of GO content in the membrane. Both internal and external diffusion have no influence on the catalytic activity. The catalytic membrane dosage, reaction temperature and methanol/oleic acid molar ratio affected its catalytic performance significantly. Among all the prepared membranes, the membrane annealed at 150 °C exhibited the best catalytic performance, with a conversion of over 85 % even after six cycles.
Brønsted Acidic Dicationic Ionic Liquid Immobilized on Fe3O4@SiO2 Nanoparticles as an Efficient and Magnetically Separable Catalyst for the Synthesis of Bispyrazoles
Authors: Rezaei Fahimeh , Ali Amrollahi Mohammad , Khalifeh Reza 
Published: February 2020

AbstractIn this research article, brønsted acidic dicationic ionic liquid immobilized on silica‐coated iron oxide support and its catalytic activity was investigated in the synthesis of bis‐pyrazol‐5‐ols under solvent‐free conditions. The prepared catalyst was characterized by different analytical tools such as XRD, FT‐IR, TGA, TEM, and SEM techniques. The catalyst can be recycled at least five times with the remaining of its catalytic activity. The easy recovery, reusability, and excellent activity of the catalyst as well as easy workup are other remarkable advantages of this method.
Application of N,N’‐Bis(acetylacetonato)propylenediimine Copper(II) Complex as Mediator for Glucose Biosensor
Authors: Perušković Danica S. , Stevanović Nikola R. , Kovačević Gordana N. , Stanković Dalibor M. , Lolić Aleksandar Đ. , Baošić Rada M. 
Published: February 2020

AbstractA new glucose biosensor for selective and sensitive determination of glucose in beverage samples was developed. A copper complex with a Schiff base, N,N’‐bis(acetylacetonato) propylenediimine, was used as a mediator. It was mixed with glucose oxidase (GOx) and prepared as carbon paste electrode (CPE). Cyclic voltammetry was used for electrochemical measurements. The biosensor showed improved sensitivity when enzyme mediator ratio was 1 : 5, and working pH was 6.6 in 0.1 M phosphate buffer. The linear response of the biosensor for glucose concentration was in the range from 0.5 to 10 mM, with low detection limit of 0.36 mM (calculated as 3 s/n) and sensitivity of 0.16 μA/mM. The reproducibility of the biosensor, calculated as relative standard deviation, was 1.9% for 6 intra‐day measurements. Biosensor was stored at +4 °C between experiments, and it was stable during 14 days after the preparation. The developed biosensor was applied on determination of glucose in commercial beverages (apple and cherry juice) and obtained results showed good agreement with the reference method.
Mesoporous Metal–Metalloid Amorphous Alloys: The First Synthesis of Open 3D Mesoporous Ni‐B Amorphous Alloy Spheres via a Dual Chemical Reduction Method
Authors: Kang Yunqing , Henzie Joel , Gu Huajun , Na Jongbeom , Fatehmulla Amanullah , Shamsan Belqes Saeed A. , Aldhafiri Abdullah M. , Farooq W. Aslam , Bando Yoshio , Asahi Toru , Jiang Bo , Li Hexing , Yamauchi Yusuke 
Published: February 2020

AbstractSelective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal–boron alloys have a tunable, glass‐like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel–boron (Ni‐B) alloy is reported. The hydrogenation of benzyl cyanide to β‐phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni‐B alloy spheres have a turnover frequency value of 11.6 h−1, which outperforms non‐porous Ni‐B spheres with the same composition. The bottom‐up synthesis of mesoporous transition metal–metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth‐abundant catalysts.
Development of Novel Cathode with Large Lithium Storage Mechanism Based on Pyrophosphate‐Based Conversion Reaction for Rechargeable Lithium Batteries
Authors: Lee Yongseok , Jo Jae Hyeon , Park Hyunyoung , Ko Wonseok , Kang Jungmin , Myung Seung‐Taek , Sun Yang‐Kook , Kim Jongsoon 
Published: February 2020

AbstractA conversion‐reaction‐based nanosized Cu2P2O7–carbon composite is investigated as a novel cathode material with superior capacity for lithium‐ion batteries. To overcome the sluggish kinetics of the conversion reaction, the nanosized Cu2P2O7–carbon composite is prepared by high‐energy ball‐milling of Cu2P2O7 and conductive carbon to achieve simultaneous nanosizing and carbon mixing. The nanosized Cu2P2O7–carbon composite exhibits a large specific capacity of ≈355 mAh g−1 with an average operation voltage of ≈2.8 V (vs Li+/Li). Moreover, even at 10C (1C = 355 mA g−1), the composite delivers a capacity of ≈215 mAh g−1, corresponding to ≈60% of its theoretical capacity. For 400 cycles at 1C, the nanosized Cu2P2O7–carbon composite exhibits capacity retention of ≈72% compared with the initial capacity as well as high Coulombic efficiency of more than 99%. The reversible conversion reaction mechanism of the nanosized Cu2P2O7–carbon composite under the Li‐cell system is confirmed using various techniques, including operando/ex situ X‐ray diffraction, X‐ray absorption near edge structure spectroscopy, extended X‐ray absorption fine structure spectroscopy, and transmission electron microscopy. It is verified that Cu2P2O7 is converted into Li4P2O7 and metallic Cu0 on discharge and reversibly recovered to Cu2P2O7 on charge.
Stray Rates of Natural‐Origin Chinook Salmon and Steelhead in the Upper Columbia River Watershed
Authors: Pearsons Todd N. , O'Connor Rolland R. 
Published: February 2020

AbstractDespite the importance of straying in understanding the ecology of Pacific salmon Oncorhynchus spp. and steelhead O. mykiss, most of what is known about salmon and steelhead straying comes from tagged hatchery fish. We provide estimates of donor straying by natural‐origin spring, summer, and fall Chinook Salmon O. tshawytscha and summer steelhead at three spatial scales in the upper Columbia River watershed by using PIT tags. In total, 823,770 natural‐origin Chinook Salmon and steelhead were PIT‐tagged as juveniles in the Wenatchee, Entiat, Methow, and Okanogan River subbasins and tributaries and the upper Columbia River between 2002 and 2017. Anadromous adults with PIT tags (n = 2,611) were detected at a variety of antenna arrays in the Columbia River basin between 2004 and 2018. Mean donor stray rates of each population were less than 1% at the basin scale (range = 0.0–0.7%), less than 10% at the subbasin scale (range = 0.0–9.8%), and less than 15% at the tributary scale (range = 0.0–14.3%). Many of the populations (11 of 28) that were evaluated across all spatial scales did not have any strays detected, and the mean of means for both species’ stray rates at all spatial scales was generally less than 5% (range = 0.2–4.0%). Chinook Salmon and steelhead strayed at similar rates when originating from the same subbasins and tributaries. Most straying occurred in an upstream direction at the subbasin (84%) and tributary (94%) scales. Variation in stray rates was most consistently associated with spatial scale and location and was less than 15% for both species at all spatial scales.