bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implications for the mesopelagic microbial gardening hypothesis as determined by experimental fragmentation of Antarctic krill fecal pellets
Authors: Cavan Emma L. , Kawaguchi So , Boyd Philip W. 
Published: December 2020

Abstract

Detritivores need to upgrade their food to increase its nutritional value. One method is to fragment detritus promoting the colonization of nutrient‐rich microbes, which consumers then ingest along with the detritus; so‐called microbial gardening. Observations and numerical models of the detritus‐dominated ocean mesopelagic zone have suggested microbial gardening by zooplankton is a fundamental process in the ocean carbon cycle leading to increased respiration of carbon‐rich detritus. However, no experimental evidence exists to demonstrate that microbial respiration rates are higher on recently fragmented sinking detrital particles.

Using aquaria‐reared Antarctic krill fecal pellets, we showed fragmentation increased microbial particulate organic carbon (POC) turnover by 1.9×, but only on brown fecal pellets, formed from the consumption of other pellets. Microbial POC turnover on un‐ and fragmented green fecal pellets, formed from consuming fresh phytoplankton, was equal. Thus, POC content, fragmentation, and potentially nutritional value together drive POC turnover rates.

Mesopelagic microbial gardening could be a risky strategy, as the dominant detrital food source is settling particles; even though fragmentation decreases particle size and sinking rate, it is unlikely that an organism would remain with the particle long enough to nutritionally benefit from attached microbes. We propose “communal gardening” occurs whereby additional mesopelagic organisms nearby or below the site of fragmentation consume the particle and the colonized microbes.

To determine how fragmentation impacts the remineralization of sinking carbon‐rich detritus and to parameterize microbial gardening in mesopelagic carbon models, three key metrics from further controlled experiments and observations are needed; how particle composition (here, pellet color/krill diet) impacts the response of microbes to the fragmentation of particles; the nutritional benefit to zooplankton from ingesting microbes after fragmentation along with identification of which essential nutrients are being targeted; how both these factors vary between physical (shear) and biological particle fragmentation.
The cost of ectoparasitism in Cliff Swallows declines over 35 years
Authors: Brown Charles R. , Hannebaum Stacey L. , O’Brien Valerie A. , Page Catherine E. , Rannala Bruce , Roche Erin A. , Wagnon Gigi S. , Knutie Sarah A. , Moore Amy T. , Brown Mary B. 
Published: December 2020

AbstractHost–parasite dynamics often vary over time, brought about by changes in the parasite’s virulence or the host’s ability to resist or tolerate the parasite. Although virulence evolution in microparasites is well studied, we know little about temporal change in the pathogenicity of macroparasites such as blood‐feeding insects. Using data collected over 35 yr, we report a reduction in pathogenicity of the hematophagous swallow bug (Cimex vicarius) on its Cliff Swallow (Petrochelidon pyrrhonota) host. Relative to experimentally fumigated, parasite‐free nests, the negative effects of bugs on nestling swallow body mass and survival were less in the later years of the study than in the earlier years, and the negative relationship between nestling body mass and bug abundance became weaker over time. The survival of adult birds exposed to swallow bugs increased throughout the study, while survival of birds from parasite‐free nests decreased over time. Swallow bug abundance per nest, bug body size, and bug age ratios did not change during the study. Between‐colony transmission of bugs showed less immigration into larger colonies than in earlier studies, but there was no net change in transmission. Cliff Swallows did not reduce their exposure to bugs over time by being more likely to avoid infested nest or colony sites. Parents increased the number of food deliveries to their offspring over time in the presence of parasites, but the total amount of food delivered was unchanged. The reduced cost of swallow bug ectoparasitism does not seem related to changes in parasite narrow‐sense virulence, the host’s avoidance of parasites, the presence of alternative hosts for bugs, or climate‐driven phenological mismatches. The results probably reflect the Cliff Swallow’s evolving of greater tolerance to swallow bugs, brought about by the bird’s shift from natural cliff nesting sites to artificial structures that may harbor more bugs than natural cliffs. This study shows that hosts can respond relatively rapidly to high levels of parasitism, and provides support for models that suggest the evolution of tolerance should be expected in some host–parasite systems.
Flexible Piezoelectric Chitosan and Barium Titanate Biocomposite Films for Sensor Applications
Authors: Guzmán Sierra Dayana L. , Bdikin Igor , Tkach Alexander , Vilarinho Paula M. , Nunes Cláudia , Ferreira Paula 
Published: December 2020

AbstractThere is currently a demand for flexible biomedical sensors. Characteristics as soft, thin, elastic, flexible and comfortable to the contact with skin should be matched with performance and ultimately made of sustainable, and biocompatible materials. In this work, chitosan as a flexible biodegradable polymeric matrix was combined with ferroelectric BaTiO3 particles obtained by hydrothermal synthesis to prepare flexible films. The biocomposites have high flexibility and the addition of particles improves the elasticity of pristine chitosan films. Of relevance towards the targeted application, the biocomposites exhibit a better resistance to water than chitosan. The dielectric permittivity increases with the addition of BaTiO3 particles. The observation of d33 and d15 by PFM, confirms the presence of piezoelectric domains corresponding to the location of BaTiO3 particles. These results contribute to the understanding of the role of functional oxides on the chemical and physical behavior of biobased polymers, creating opportunities to design optimized and more sustainable flexible piezoelectric sensor films.
A Tunable Amorphous Heteronuclear Iron and Cobalt Imidazolate Framework Analogue for Efficient Oxygen Evolution Reactions
Authors: Zhao Qingyun , Lin Xiao , Zhou Jing , Zhao Chong , Zheng Dehua , Song Sanzhao , Jing Chao , Zhang Linjuan , Wang Jian‐Qiang 
Published: December 2020

AbstractThe structural diversity and tunable functionality of the amorphous metal‐organic frameworks (aMOFs) highlights this class of materials as a promising candidate for the development of sustainable energy technologies. The electrocatalytic performance in oxygen evolution reaction (OER) can be greatly improved by incorporating the hetero‐metallics into MOFs. Herein, the OER performance was significantly improved by the incorporation of Fe3+ ions into the crystalline cobalt‐based MOF, leading to amorphous structure. Benefiting from the optimized surface morphology and electrochemical surface area, charge transport, was greatly facilitated. The Fe/Co aMOF with 1/4 ratio (labeled as AFC‐MOFs (1 : 4)) exhibited an excellent and stable OER activity, with an ultralow overpotential (256 mV at 10 mA cm−2) and Tafel slope of 42.7 mV dec−1. XAS found that the majority of Co2+ in AFC‐MOFs (1 : 4) is converted to low‐spin Co3+ upon OER, while Fe3+ is maintained during the OER process, supporting the synergistic catalytic mechanism between Fe and Co. This material outperforms benchmark IrO2, which could be attributed to the hollow amorphous structure and the optimized electronic properties.
From Missing Links to New Records: A Series of Novel Polychlorine Anions
Authors: Voßnacker Patrick , Keilhack Thomas , Schwarze Nico , Sonnenberg Karsten , Seppelt Konrad , Malischewski Moritz , Riedel Sebastian 
Published: December 2020

AbstractHerein we report the synthesis and structural characterization of four novel polychloride compounds. The compounds [CCl(NMe2)2][Cl(Cl2)3] and [NPr4][Cl(Cl2)4] have been obtained from the reaction of the corresponding chloride salts with elemental chlorine at low temperature. They are the missing links in the series of polychloride monoanions [Cl(Cl)n]− (n=1–6). Additionally, the reaction of decamethylferrocene with elemental chlorine was studied yielding [Cp*2Fe]2[Cl20], which contains the largest known polychloride [Cl20]2− to date, and [Cp*2Fe][Cl(Cl2)4(HF)], which is the first example of a polychloride‐HF network stabilized by strong hydrogen and halogen bonding. All compounds have been characterized by single‐crystal X‐ray diffraction, Raman spectroscopy and quantum‐chemical calculations.
Characterization of hypercrosslinked polymer adsorbent based on carbazole to achieve higher CO2 capture
Authors: Ramezanipour Penchah Hamid , Najafi Pegah , Ghaemi Ahad , Ghanadzadeh Gilani Hossein 
Published: December 2020

AbstractIn this study, a hypercrosslinked polymer (HCP) adsorbent based on Friedel–Crafts reaction and carbazole as a monomer was synthesized and used for CO2 capture. The HCP adsorbent is characterized by Fourier transform infrared spectroscopy, Brunauer, Emmett and Teller analysis, and energy dispersive spectroscopy. The effects of crosslinker to carbazole ratio, synthesis time and catalyst type, and their interactions were evaluated by response surface methodology using central composite design. The result showed that the optimum adsorption capacity (191.2 mg/g) was obtained at a crosslinker to carbazole ratio of 2.7, synthesis time of 11.2 h, and FeCl3 as catalyst of the reaction. The experimental adsorption data fitted by adsorption isotherm and kinetic models in the optimized parameter values and correlation coefficient (R2) were considered to select the best model. The results showed that Hill isotherm and Elovich kinetic models have higher R2 values than other models. Finally, the feasibility of the adsorption process was determined by thermodynamic modeling and enthalpy, entropy, and Gibbs free energy differences of adsorption at 298.15 K and 5 bar were calculated −15.035 kJ/mol, −0.025 kJ/mol.K and −7.822 kJ/mol, respectively.
Acute Polychlorinated Biphenyl Benthic Invertebrate Toxicity Testing to Support the 2017 Chronic Dose–Response Sediment Injury Model
Authors: Finkelstein Kenneth , Wirth Edward F. , Chung K.W. , Shaddrix B.S. , Pisarski E.C. , Rios C. 
Published: December 2020

Abstract
As managers and decision makers evaluate pollutant risk, it is critical that we are able to measure an assessment of the injury. Often, these estimates are difficult to determine for benthic organisms, so in 2017 a chronic polychlorinated biphenyl (PCB) sediment dose–response model to predict benthic invertebrate injury was proposed. Given both natural resource trustee and consultant questions following publication concerning that the aqueous chronic toxicity testing data used in the 2017 model development were primarily from the 1970s and 1980s, this follow-up short communication is meant to provide the user some additional data that are more recent. With the advances in analytical and quantitative environmental chemistry (i.e., better detection limits and congener separation), we chose to complete acute aquatic toxicity testing using 3 estuarine invertebrates and lethal endpoints (20 and 50% lethal concentrations). This acute testing was selected because chronic aquatic testing for PCBs outside of the data used in the 2017 study was not available to us. The aquatic results used in the present study were changed to sediment using equilibrium partitioning, as done in the 2017 chronic model, after using the same organic–carbon partition coefficient and total organic carbon for our equilibrium partitioning (EqP)–measured calculations. Based on these acute aquatic toxicity results and a general acute-to-chronic injury concentration ratio of approximately 10, we found that the 2017 model was valid and, hence, that a 1.0 µg/g chronic PCB sediment criterion is a reasonable estimation of potential benthic invertebrate injury. This was followed by spiked sediment tests where percent acute sediment injury was compared to the EqP-derived chronic value and the results from 2017; modest agreement is shown. Environ Toxicol Chem 2021;40:1188–1193. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.
Per- and Polyfluoroalkyl Substances Are Positively Associated with Thyroid Hormones in an Arctic Seabird
Authors: Ask Amalie Vigdel , Jenssen Bjørn Munro , Tartu Sabrina , Angelier Frédéric , Chastel Olivier , Gabrielsen Geir Wing 
Published: December 2020

Abstract
Per- and polyfluoroalkyl substances (PFAS) are associated with several disrupted physiological and endocrine parameters. Regarding endocrine mechanisms, laboratory studies suggest that PFAS could disrupt the thyroid hormone system and alter circulating thyroid hormone concentrations. Thyroid hormones play a ubiquitous role—controlling thermoregulation, metabolism, and reproduction. However, evidence for disruption of thyroid hormones by PFAS remains scarce in wildlife. The present study investigated the associations between concentrations of PFAS, thyroid hormones, and body condition in an arctic seabird, the black-legged kittiwake (Rissa tridactyla). We collected blood from kittiwakes sampled in Svalbard, Norway (2013 and 2014). Plasma samples were analyzed for total thyroxine (TT4) and total triiodothyronine (TT3) concentrations; detected PFAS included branched and linear (lin) C8 perfluoroalkyl sulfonates (i.e., perfluoroctane sulfonate [PFOS]) and C9-C14 perfluoroalkyl carboxylates (PFCAs). The dominant PFAS in the kittiwakes were linPFOS and C11- and C13-PFCAs. Generally, male kittiwakes had higher concentrations of PFAS than females. We observed positive correlations between linPFOS, C10-PFCA, and TT4 in males, whereas in females C12-14-PFCAs were positively correlated to TT3. Interestingly, we observed contrasted correlations between PFAS and body condition; the direction of the relationship was sex-dependent. Although these results show relationships between PFAS and circulating thyroid hormone concentrations in kittiwakes, the study design does not allow for concluding on causal relationships related to effects of PFAS on the thyroid hormone system. Future experimental research is required to quantify this impact of PFAS on the biology of kittiwakes. The apparently different associations among PFAS and body condition for males and females are puzzling, and more research is required. Environ Toxicol Chem 2021;40:820–831. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Abstract
The thyroid hormones (THs) triiodothyronine and thyroxine and per- and polyfluoroalkyl substances (PFAS) were examined in plasma from black-legged kittiwakes (Rissa tridactyla). We found a positive association between several PFAS and the THs. T3 = triiodothyronine; T4 = thyroxine.
Subspace leakage reduced nonuniform sparse Fibonacci‐like planar array to estimate azimuth and elevation angles of both Angle of Arrival and Angle of Departure
Authors: Vethanayagam Angeline Beulah , Narasimhan Venkateswaran 
Published: December 2020

AbstractEstimation of azimuth and elevation angles of both Angle of Arrival and Angle of Departure is a challenging research topic in 5G smart antenna technology. The key contributions of this work involve two novel algorithms implemented in a uniform planar array for the estimation of the arrival and departure angles using the received signal from the coherent users. One of the two algorithms reduces search complexity without any reduction in the angular resolution of the estimated angles. This is done through selection of active antennas in the uniform planar array to make it sparse without creating angle ambiguity. The second method improves the angular resolution in estimating the angles through reduction in the subspace leakage that occurs between the signal and noise subspace. Numerical simulations prove the proposed two algorithms producing a high angular resolution with reduced complexity.
The interference alignment scheme based on subspace differentiation for multicell multiuser multiple‐input‐multiple‐output uplink channels
Authors: Li Shibao , Ye Wei , Guo Lin , Liu Jianhang , Huang Tingpei , Cui Xuerong , Zhang Yucheng 
Published: December 2020

AbstractThe traditional subspace interference alignment (IA) schemes in the multicell multiuser multiple‐input‐multiple‐output (MIMO) network align interference into the multidimensional subspace to reduce the dimension of the interference space, but the choice of subspace is random, and the difference between users is not considered. Such schemes may leave large intercell interference when the difference between users is large. To solve this problem, this article proposes the IA scheme based on subspace differentiation for multicell multiuser MIMO uplink channels. First, based on the transmit power and the distance to base stations in other cells, each user analyzes the interference value it will cause. The interference value of each user is represented by actual interference power (AIP). Within each cell, the users are reordered according to the AIP. When performing interference reduction, the signals of the users with large interference are merged into the subspace composed of the signals of the users with small interference, which can further reduce the final intercell interference. The multidimensional merge weight is assigned according to the AIP. The smaller the interference value of the dimension, the more interference it merges. The experimental simulation data show that the scheme implemented in this article can improve the proportion of the desired signals in the received signals of the receivers, thereby improving the overall system rate. When the user difference in transmit power and distance is large, the proposed scheme has a particularly obvious advantage.
Do put warrants unwind short‐sale restrictions? Further evidence from the Taiwan Stock Exchange
Authors: Chuang Yi‐Wei , Tsai Wei‐Che , Weng Pei‐Shih , Yin Chi 
Published: December 2020

AbstractThis study investigates the relationship between stock short‐selling restrictions and bearish equity warrants on the Taiwan Stock Exchange to clarify the substitutive role of put warrants for underlying stocks subject to short‐sale constraints. We show that put warrant transactions increase when short selling is prohibited in the spot market and the substitutive increase in trading also leads to wider bid–ask spreads and higher implied volatility for put warrants. Moreover, we find that the increased trading activities in put warrants could subsequently affect spot market trading through warrant issuers' required dynamic hedging behaviors.
The term structure of the VXX option smirk: Pricing VXX option with a two‐factor model and asymmetry jumps
Authors: Tan Xiaoyu , Wang Chengxiang , Lin Wei , Zhang Jin E. , Li Shenghong , Zhao Xuejun , Zhang Zili 
Published: December 2020

AbstractThis paper proposes a comprehensive jump‐to‐default extended two‐factor stochastic volatility plus asymmetry jumps model for the valuation of VXX derivatives. The model provides a more flexible modeling of the time variation in VXX options smirk and VXX options volatility term structure compared with previous model alternatives. Empirical results indicate that our model outperforms Bao et al.'s model by 28.19% in‐sample and 23.38% out‐of‐sample. Moreover, our model improves the probability that the estimated prices fall inside the quoted option bid‐ask spread and has a better fitting capacity for the term structure of VXX implied volatility, especially for out‐of‐the‐money options.
Advanced Material Against Human (Including Covid‐19) and Plant Viruses: Nanoparticles As a Feasible Strategy
Authors: Tortella Gonzalo R. , Rubilar Olga , Diez María Cristina , Padrão Jorge , Zille Andrea , Pieretti Joana C. , Seabra Amedea B. 
Published: December 2020

AbstractThe SARS‐CoV‐2 virus outbreak revealed that these nano‐pathogens have the ability to rapidly change lives. Undoubtedly, SARS‐CoV‐2 as well as other viruses can cause important global impacts, affecting public health, as well as, socioeconomic development. But viruses are not only a public health concern, they are also a problem in agriculture. The current treatments are often ineffective, are prone to develop resistance, or cause considerable adverse side effects. The use of nanotechnology has played an important role to combat viral diseases. In this review three main aspects are in focus: first, the potential use of nanoparticles as carriers for drug delivery. Second, its use for treatments of some human viral diseases, and third, its application as antivirals in plants. With these three themes, the aim is to give to readers an overview of the progress in this promising area of biotechnology during the 2017–2020 period, and to provide a glance at how tangible is the effectiveness of nanotechnology against viruses. Future prospects are also discussed. It is hoped that this review can be a contribution to general knowledge for both specialized and non‐specialized readers, allowing a better knowledge of this interesting topic.
How microglia sense and regulate neuronal activity
Authors: Umpierre Anthony D. , Wu Long‐Jun 
Published: December 2020

AbstractMicroglia are innate immune cells of the central nervous system that sense extracellular cues. Brain injuries, inflammation, and pathology evoke dynamic structural responses in microglia, altering their morphology and motility. The dynamic motility of microglia is hypothesized to be a critical first step in sensing local alterations and engaging in pattern‐specific responses. Alongside their pathological responses, microglia also sense and regulate neuronal activity. In this review, we consider the extracellular molecules, receptors, and mechanisms that allow microglia to sense neuronal activity changes under both hypoactivity and hyperactivity. We also highlight emerging in vivo evidence that microglia regulate neuronal activity, ranging from physiological to pathophysiological conditions. In addition, we discuss the emerging role of calcium signaling in microglial responses to the extracellular environment. The dynamic function of microglia in monitoring and influencing neuronal activity may be critical for brain homeostasis and circuit modification in health and disease.