bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triboelectric Charging and Separation of Fine Powder Mixtures
Authors: Hansen Leonard , Wollmann Annett , Weers Martin , Benker Bernd , Weber Alfred P. 
Published: February 2020

AbstractFor increasingly finer powders, the material‐specific separation at high loadings is a challenging task, for instance in recycling processes. Here, a combination of triboelectric charging and electrostatic separation was investigated for powder mixtures of talcum and calcite. The dependencies of the triboelectric charge on the mass loading, the gas velocity, and the mixture ratio were investigated. While higher charge levels were achieved with increasing gas velocity, the mass loading had an opposite effect on the net charge. Although bipolar charge distributions were observed within pure materials and mixtures, electrical neutralization did not occur in the mixtures. Therefore, already in a non‐optimized setup, a decent degree of material enrichment (of up to 53 %) was found on the separating electrodes.
Chameleonic Behavior of the α‐Methylcyclopropyl Group and Its Through‐Space Interactions: A Route to Stabilized Three Redox States in Diarylnitroxides
Authors: Levitskiy Oleg A. , Dulov Dmitry A. , Bogdanov Alexey V. , Grishin Yury K. , Nefedov Sergey E. , Magdesieva Tatiana V. 
Published: February 2020

AbstractThe α‐methylcyclopropyl (MCP) group with conformationally dependent electronic properties is suggested as an additional structural “instrument” for stabilization of both open‐shell and ionic states of diarylnitroxides, to be used as “ambipolar” redox active materials. New MCP‐substituted diphenylnitroxides (fully characterized by electrochemical, spectral, and X‐ray data) are the most stable nitroxides of the diaryl type known to date [τ1/2 in benzene exceeds three months (2310 h)]. The radicals are capable to reversible oxidation and reduction, yielding stable oxoammonium cations and aminoxyl anions. DFT investigation of the electronic structure and geometry of the compounds confirmed the conformational switching of the cyclopropyl orientation relative to the adjacent aromatic π system is dependent on the nitroxide's redox state. Additional through‐space stabilizing interaction between the π‐acceptor orbital of the NO+ moiety and the cyclopropyl “banana” bond orbital was also detected, highlighting its good hyperconjugative ability. The estimated σ(para)MCP value (−0.32) confirms its strong electron‐donating properties.
Template‐Free Self‐Assembly of Molecular Trefoil Knots and Double Trefoil Knots Featuring Cp*Rh Building Blocks
Authors: Shan Wei‐Long , Gao Xiang , Lin Yue‐Jian , Jin Guo‐Xin 
Published: February 2020

AbstractUnderstanding and controlling the topology of self‐assembled structures plays a fundamental role in supramolecular chemistry. Herein, the preparation of a series of tetranuclear metallarectangles and hexanuclear trefoil knots featuring Cp*Rh building blocks by template‐free self‐assembly with four different rigid and flexible ligands is described. Transformations between the trefoil knots and the corresponding macrocycles can be induced by using concentration effects. Remarkably, the hexanuclear trefoil knot 5 was shown to assemble further to provide rare examples of [12+1] heteronuclear double trefoil knots (5 a/5 b/5 c/5 d) through coordination of the amide oxygen atoms to the secondary metal ions Na+/K+/Ca2+/Cd2+. The synthetic results are supported by single‐crystal XRD.
Methods for determining the absolute configurations of marine ladder‐shaped polyethers
Authors: Satake Masayuki , Yasumoto Takeshi 
Published: February 2020

AbstractMarine dinoflagellates produce a unique family of bioactive substances featuring multiple ether rings aligned in a ladder shape. These are large, complex molecules with potent bioactivity. Targeted chiral centers sit on either the skeletal ladders or on the side chains of these compounds. However, the laborious steps of isolation and purification severely diminish the amount of sample available for assigning these chiral centers via structural investigations. Three important methods were used to assign the stereochemistry of the molecules, (a) circular dichroism (CD) spectroscopy, (b) labeling with fluorescent chiral reagents for high‐performance liquid chromatography (HPLC) analysis, and (c) derivatization with anisotropic reagents for nuclear magnetic resonance (NMR) analysis. The addition of fluorescent chiral reagents allowed for the use of much less material than typically required. In this review, we present examples of the determination of absolute configurations in ladder‐shaped polyethers. The targeted compounds include ciguatoxins (CTXs), gymnocin‐B, gambieric acids, prymnesin‐2, maitotoxin, yessotoxins, gambierol, brevisamide, and brevisin.
Phase Diagram for a Lysyl‐Phosphatidylglycerol Analogue in Biomimetic Mixed Monolayers with Phosphatidylglycerol: Insights into the Tunable Properties of Bacterial Membranes
Authors: Wölk Christian , Youssef Hala , Guttenberg Thomas , Marbach Helene , Vizcay‐Barrena Gema , Shen Chen , Brezesinski Gerald , Harvey Richard D. 
Published: February 2020

AbstractIon pairing between the major phospholipids of the Staphylococcus aureus plasma membrane (phosphatidylglycerol – PG and lysyl‐phosphatidylglycerol – LPG) confers resistance to antimicrobial peptides and other antibiotics. We developed 3adLPG, a stable synthetic analogue which can substitute for the highy‐labile native LPG, in biophysical experiments examining the membrane‐protecting role of lipid ion pairing, in S. aureus and other important bacteria. Here we examine the surface charge and lipid packing characteristics of synthetic biomimetic mixtures of DPPG and DP3adLPG in Langmuir monolayers, using a combination of complementary surface‐probing techniques such as infrared reflection‐absorption spectroscopy and grazing‐incidence x‐ray diffraction. The resultant phase diagram for the ion paired lipids sheds light on the mixing behavior of lipids in monolayer models of resistant phenotype bacterial membranes, and provides a platform for future biophysical studies.
Phosphoprotein Detection with a Single Nanofluidic Diode Decorated with Zinc Chelates
Authors: Nasir Saima , Ali Mubarak , Ahmed Ishtiaq , Niemeyer Christof M. , Ensinger Wolfgang 
Published: February 2020

AbstractWe report a nanofluidic device for the label‐free detection of phosphoprotein (PPn) analytes. To achieve this goal, a metal ion chelator, namely 4‐[bis(2‐pyridylmethyl)aminomethyl]aniline (DPA−NH2) compound was synthesized. Single asymmetric nanofluidic channels were fabricated in polyethylene terephthalate (PET) membranes. The chelator (DPA−NH2) molecules are subsequently immobilized on the nanochannel surface, followed by the zinc ion complexation to afford DPA−Zn2+ chelates, which act as ligand moieties for the specific binding of phosphoproteins. The success of the chemical reaction and biomolecular recognition process that occur in a confined geometry can be monitored from the changes in electrical readout of the nanochannel. The nanofluidic sensor has the ability to sensitively and specifically detect lower concentrations (≥1 nM) of phosphoprotein (albumin and α‐casein) in the surrounding environment as evidenced from the significant decrease in ion current flowing through the nanochannels. However, dephosphoproteins such as lysozyme and dephospho‐α‐casein even at higher concentration (>1 μM) could not induce any significant change in the transmembrane ion flux. This observation indicated the sensitivity and specificity of the proposed nanofluidic sensor towards PPn proteins, and has potential for use in differentiating between phosphoproteins and dephosphoproteins.
Quantitative characterization of proximate sensing canopy traits in the SoyNAM population
Authors: Hall Ben P. , Xavier Alencar , Moreira Fabiana , Casteel Shaun , Rainey Katy M. 
Published: February 2020

AbstractThe average increase of soybean [Glycine max (L.) Merr.] grain yield per year is not enough to meet the estimated need by 2050. Contributing factors may include narrowing genetic diversity in cultivated soybean germplasm arising from direct selection for grain yield and insufficient knowledge of the genetic influences on physiological traits associated with grain yield. Canopy development plays a critical role in the light intercepted by soybean crops throughout the growing season. Rapid canopy closure facilitates complete light interception and optimizes growth dynamics, ultimately increasing biomass accumulation and grain yield. This study sought to use ground‐based digital imagery as a phenotyping tool for quantitative characterization of seasonal canopy coverage and light interception in the genetically diverse Soybean Nested Association Mapping (SoyNAM) population. We took weekly measurements of canopy coverage from early vegetative to mid‐reproductive growth for 5,600 recombinant inbred lines during the 2013 and 2014 seasons. An asymptotic logistic growth curve fit to the coverage data allowed us to estimate daily changes in canopy coverage in the intervals between the sampling dates, enabling calculation of canopy dynamic parameters. These parameters included average canopy coverage, cumulative intercepted photosynthetically active radiation for the total sampling period, vegetative growth period, reproductive growth period, and the number of days required to reach 30, 50, and 70% canopy coverage. Variance component estimation showed that genetic differences among families significantly influenced variation in phenotypic expression for all canopy parameters. The narrow‐sense heritabilities for all canopy parameters were high (h2 = .81–.90), suggesting opportunities for genetic gains in canopy development through selection of superior genotypes.
Cobalt‐Catalyzed Oxidative C−H Activation: Strategies and Concepts
Authors: Mei Ruhuai , Dhawa Uttam , Samanta Ramesh C. , Ma Wenbo , Wencel‐Delord Joanna , Ackermann Lutz 
Published: February 2020

AbstractInexpensive cobalt‐catalyzed oxidative C−H functionalization has emerged as a powerful tool for the construction of C−C and C−Het bonds, which offers unique potential for transformative applications to modern organic synthesis. In the early stage, these transformations typically required stoichiometric and toxic transition metals as sacrificial oxidants; thus, the formation of metal‐containing waste was inevitable. In contrast, naturally abundant molecular O2 has more recently been successfully employed as a green oxidant in cobalt catalysis, thus considerably improving the sustainability of such transformations. Recently, a significant momentum was gained by the use of electricity as a sustainable and environmentally benign redox reagent in cobalt‐catalyzed C−H functionalization, thereby preventing the consumption of cost‐intensive chemicals while at the same time addressing the considerable safety hazards related to the use of molecular oxygen in combination with flammable organic solvents. Considering the unparalleled potential of the aforementioned approaches for sustainable green synthesis, this Review summarizes the recent progress in cobalt‐catalyzed oxidative C−H activation until early 2020.
Paeoniflorin alleviates lipopolysaccharide‐induced disseminated intravascular coagulation by inhibiting inflammation and coagulation activation
Authors: Fang Yushan , Wu Liang‐Cai , Ma Kanglong , Pan Guopeng , Yang Shangqi , Zheng Yanghan , Li Yanchang 
Published: February 2020

AbstractLipopolysaccharide (LPS) is a toxic component of the outer membrane of gram‐negative bacteria that can activate the blood coagulation system, leading to disseminated intravascular coagulation (DIC). DIC is a syndrome characterized by thromboembolism and multiple organ failure. Herein, the beneficial effect of paeoniflorin (PF) on the alleviation of LPS‐induced DIC was investigated with an experimental DIC mouse model. Briefly, mice were randomly divided into the following six groups: (1) control; (2) LPS; (3) heparin; (4) low‐PF treatment; (5) medium‐PF treatment; and (6) high‐PF treatment. The histological morphology of the liver and kidney was observed, and the coagulation indicators (such as prothrombin time), function indicators (such as alanine transferase), and inflammatory factors (such as TNF‐α) were detected. Additionally, an in vitro cell inflammation model using RAW 264.7 murine macrophages was established. Activation of the nuclear factor kappa B (NF‐κB) signaling pathway and tumor necrosis factor‐α (TNF‐α) were determined by western blotting. Based on our findings, PF could significantly improve the histological morphology of the liver and kidney, indicating that PF protects the liver and kidney against damage induced by LPS. Additionally, PF improved the function and coagulation indicators and reduced the production of inflammatory factors. In vitro, PF inhibited the expression of TNF‐α by suppressing NF‐κB signaling pathway activation. Collectively, our findings support the hypothesis that PF has anti‐inflammatory and anticoagulation effects for the alleviation of LPS‐induced DIC. PF is thus a potential co‐treatment option for DIC.
Fragmentation reduces community‐wide taxonomic and functional diversity of dispersed tree seeds in the Central Amazon
Authors: Hooper Elaine R. , Ashton Mark S. 
Published: February 2020

AbstractThe Amazon harbors one of the most diverse tree floras on earth, and most species depend on mutualists for pollination and seed dispersal. This makes them susceptible to reproductive decline in fragmented forest because many of these mutualists suffer area‐related extinction in fragments. It remains unknown, however, whether this highly biodiverse tree flora will reproduce and ultimately persist in fragmented forest. We conducted a 2‐yr study of seed fall in an experimentally fragmented, highly diverse Central Amazonian forest. We determined the effect of fragment size (1, 10, 100 ha and continuous forest control) on the density, species richness, functional diversity and functional composition of seeds separated into two data sets: dispersed tree seeds, and undispersed tree seeds. Our results show a 3× reduction in the density of undispersed, non‐pioneer tree seeds in fragments of all sizes, indicating reduced seed production of the non‐pioneer tree community. The density of dispersed tree seeds was reduced by 6× in fragments of all sizes, while species richness was reduced by 6× in 1‐ha fragments and by 3× in 10‐ and 100‐ha fragments compared to intact forest. This provides evidence of reduced community‐wide seed dispersal, which became more pronounced with declining fragment size. The functional diversity (FRic) of dispersed tree seeds was reduced 9.6× in small fragments, and significant shifts in the functional composition for 8 of the 10 reproductive and ecological traits studied were identified, suggesting compromised ecosystem functioning. These functional compositional shifts provide evidence for disrupted mutualistic processes in fragments, which include loss of pollination by bees, especially small eusocial (meliponid) bees, and loss of dispersal by primates and large birds, which reduced the frequency of large‐seeded tree species. Fragments also lost rare and mature‐forest species, and collectively these changes suggest that future tree communities in fragmented Amazonian landscapes will retain a taxonomically and functionally impoverished species pool with a biased functional composition unless efforts are undertaken to conserve dispersal by large frugivores and pollination by meliponid bees.
Using genomic information for management planning of an endangered perennial, Viola uliginosa
Authors: Lee Kyung Min , Ranta Pertti , Saarikivi Jarmo , Kutnar Lado , Vreš Branko , Dzhus Maxim , Mutanen Marko , Kvist Laura 
Published: February 2020

AbstractSpecies occupying habitats subjected to frequent natural and/or anthropogenic changes are a challenge for conservation management. We studied one such species, Viola uliginosa, an endangered perennial wetland species typically inhabiting sporadically flooded meadows alongside rivers/lakes. In order to estimate genomic diversity, population structure, and history, we sampled five sites in Finland, three in Estonia, and one each in Slovenia, Belarus, and Poland using genomic SNP data with double‐digest restriction site‐associated DNA sequencing (ddRAD‐seq). We found monophyletic populations, high levels of inbreeding (mean population FSNP = 0.407–0.945), low effective population sizes (Ne = 0.8–50.9), indications of past demographic expansion, and rare long‐distance dispersal. Our results are important in implementing conservation strategies for V. uliginosa, which should include founding of seed banks, ex situ cultivations, and reintroductions with individuals of proper origin, combined with continuous population monitoring and habitat management.
Parameterized maximum entropy models predict variability of metabolic scaling across tree communities and populations
Authors: Xu Meng 
Published: February 2020

AbstractThe maximum entropy theory of ecology (METE) applies the concept of “entropy” from information theory to predict macroecological patterns. The energetic predictions of the METE rely on predetermined metabolic scaling from external theories, and this reliance diminishes the testability of the theory. In this work, I build parameterized METE models by treating the metabolic scaling exponent as a free parameter, and I use the maximum‐likelihood method to obtain empirically plausible estimates of the exponent. I test the models using the individual tree data from an oak‐dominated deciduous forest in the northeastern United States and from a tropical forest in central Panama. My analysis shows that the metabolic scaling exponents predicted from the parameterized METE models deviate from that of the metabolic theory of ecology and exhibit large variation, at both community and population levels. Assemblage and population abundance may act as ecological constraints that regulate the individual‐level metabolic scaling behavior. This study provides a novel example of the use of the parameterized METE models to reveal the biological processes of individual organisms. The implication and possible extensions of the parameterized METE models are discussed.
Intra‐guild predation (IGP) can increase or decrease prey density depending on the strength of IGP
Authors: Chang Feng‐Hsun , Cardinale Bradley J. 
Published: February 2020

AbstractIn consumer communities, intra‐guild predation (IGP) is a commonly observed interaction that is widely believed to increase resource density. However, some recent theoretical work predicts that resource density should first decrease, and then increase as the strength of IGP increases. This occurs because weak to intermediate IGP increases the IG predator density more than it reduces the IG prey density, so that weak to intermediate IGP leads to the lowest resource density compared to weak or strong IGP. We test this prediction that basal resource density would first decrease and then increase as the strength of IGP increase. We used a well‐studied system with two protozoa species engaged in IGP and three bacteria species as the basal resources. We experimentally manipulated the percentage of the IG prey population that was available to an IG predator as a proxy for IGP strength. We found that bacterial density first decreased (by ~25%) and then increased (by ~30%) as the strength of IGP increased. Using a modified version of a published IGP model, we were able to explain ~70% of the variation in protozoa and bacterial density. Agreement of the empirical results with model predictions suggests that IGP first increased the IG predator density by consuming a small proportion of the IG prey population, which in turn increased the summed consumer density and decreased the bacterial resource density. As IGP strength increased further, the IG predator became satiated by the IG prey, which then freed the bacterial resource from predation and thus increased bacterial density. Consequently, our work shows that IGP can indeed decrease or increase basal resource density depending on its strength. Consequently, the impacts of IGP on resource density is potentially more complex than previously thought.
Dynamics of a sliding‐rocking block considering impact with an adjacent wall
Authors: Bao Yu , Konstantinidis Dimitrios 
Published: February 2020

SummaryA freestanding rigid block subjected to base excitation can exhibit complicated motion described by five response modes: rest, pure rocking, pure sliding, combined sliding‐rocking, and free flight. Previous studies on the dynamics of a rocking block have assumed that the block does not interact with neighboring objects. However, there are many applications in which the block may start or come in contact with an adjacent boundary during its motion, for example, a bookcase or cabinet colliding with a partition wall in an earthquake. This paper investigates the dynamics of a sliding‐rocking block considering impact with an adjacent wall. A model is developed in which the base and wall are assumed rigid, and impact is treated using the classical impulse and momentum principle. The model is verified by comparing its predictions in numerical simulations against those of an existing general‐purpose rigid‐body model in which impact is treated using a viscoelastic impact model. The developed model is used to investigate the effects of different parameters on the stability of a block subjected to analytical pulse excitations. It is found that wall placement (left or right) has a dominant effect on the shape of the overturning acceleration spectra for pulse excitations. In general, decreasing the gap distance, base friction coefficient, and wall coefficient of restitution enhance the stability of the block. Similar observations are made when evaluating the overturning probability of a block using earthquake floor motions.
Comparison of ammonia sorption properties and thermodynamic performance of adsorption‐based thermal energy storage system for MnCl2, CaCl2, and their composites
Authors: Jivrakh Kedar B. , Kaki Sarath Babu , Sharma Rakesh , Mendu Siva Subrahmanyam , Emadabathuni Anil Kumar 
Published: February 2020

AbstractIn this work, composite adsorbent materials are prepared using metal halide salts and expanded natural graphite (ENG). Ammonia adsorption and desorption pressure concentration isotherms of composite adsorbents are experimentally measured. The van't Hoff plots are constructed to calculate the enthalpy of a reaction during adsorption and desorption. The average value of adsorption enthalpies (∆Had) for MnCl2 + ENG and CaCl2 + ENG are 55.821 and 33.434 kJ mol−1, respectively, and average values of desorption enthalpies (∆Hdes) are 73.817 and 73.016 kJ mol−1, respectively. Comparison of ammonia sorption properties of composites and their corresponding plain salts is done. Thermodynamic analysis of adsorption thermal energy storage (ATES) system) showed that maximum gravimetric energy storage density for MnCl2 + ENG based system is 1394.83 kJ kg−1 (158.85 kWh m−3) at energy storage and ambient temperatures of 172°C and 35°C, respectively. The same for CaCl2 + ENG based system is 1350.86 kJ kg−1 (165.85 kWh m−3) at storage and ambient temperatures of 92°C and 35°C, respectively. Volumetric energy storage density is higher for CaCl2 + ENG based ATES system since it has higher density. Thermodynamic performance of composite‐based systems is compared with plain salts (MnCl2‐CaCl2) based thermal energy storage system.