bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protonation and Anion Binding Properties of Aromatic Bis‐Urea Derivatives—Comprehending the Proton Transfer
Authors: Barišić Dajana , Cindro Nikola , Kulcsár Marina Juribašić , Tireli Martina , Užarević Krunoslav , Bregović Nikola , Tomišić Vladislav 
Published: January 2019

AbstractA series of aromatic bis‐urea derivatives was prepared and their proton dissociation, as well as anion binding properties in DMSO were investigated. To this end, UV/Vis and 1H NMR spectroscopies and computational methods were employed. The synthesized molecules differed in the relative position of the urea moieties (ortho‐ and meta‐derivatives) and in the functional groups (−H, −CH3, −OCH3, −NO2) in the para‐position of the pendant phenyl groups. Remarkably high acidities of the compounds (logK1H≈14), were ascribed primarily to the stabilizing effect of the aromatic subunits. Quantum chemical calculations corroborated the conclusions drawn from experimental data and provided information from the structural point of view. Knowledge regarding protonation properties proved to be essential for reliable quantitative determination of anion binding affinities. Studied receptors were selective for acetate and dihydrogen phosphate among several anions. Formation of their complexes of 1:1 and 1:2 (ligand/anion) stoichiometries was quantitatively characterized. Proton transfer was taken into account in the course of data analysis, which was especially important in the case of AcO−. ortho‐Receptors were proven to be more efficient acetate binders, achieving coordination with all four NH groups. The meta‐analogues preferred dihydrogen phosphate, which acted as both hydrogen bond donor and acceptor. Cooperative binding was detected in the case of 1:2 H2PO4− complexes, which was assigned to formation of interanionic hydrogen bonds.
Understanding the Reactivity and Selectivity of Fluxional Chiral DMAP‐Catalyzed Kinetic Resolutions of Axially Chiral Biaryls
Authors: Maji Rajat , Ugale Heena , Wheeler Steven E. 
Published: January 2019

AbstractFluxional chiral DMAP‐catalyzed kinetic resolutions of axially chiral biaryls were examined using density functional theory. Computational analyses lead to a revised understanding of this reaction in which the interplay of numerous non‐covalent interactions control the conformation and flexibility of the active catalyst, the preferred mechanism, and the stereoselectivity. Notably, while the DMAP catalyst itself is confirmed to be highly fluxional, electrostatically driven π⋅⋅⋅π+ interactions render the active, acylated form of the catalyst highly rigid, explaining its pronounced stereoselectivity.
Pyrrhotite depression studies with DETA and SMBS on a Ni‐Cu sulphide ore
Authors: Multani Ravinder S. , Waters Kristian E. 
Published: January 2019

AbstractPyrrhotite (Po) is a common gangue mineral in Ni‐Cu sulphide ores (pentlandite {Pn}‐chalcopyrite {Cp}) and can be difficult to reject under certain circumstances. This paper summarizes the results of a lab‐scale flotation study on a reactive ore with a high Po/Pn ratio (7.5), 42 % hexagonal Po content (of total Po), and 85.9 % Ni deportment in Pn (remainder Ni largely reporting to Po), making Po rejection challenging and Ni recovery/grade targets difficult to obtain. The main objective was to assess whether the ore could be processed “as received” to achieve high Pn recovery (>85 %) while ensuring low Po recovery (<20 %), which will typically yield acceptable final concentrate grades after cleaning stages. Baseline testing showed Po depression was difficult by conventional means and required depressants. The test work was centered around the use of DETA (diethylenetriamine) for its proven effectiveness for Po depression (used with sodium metabisulphite (SMBS)). Several strategies were tested: DETA alone; DETA/SMBS; sulphuric acid/DETA/SMBS with/without aeration; and DETA/SMBS with concentrate regrind. The DETA was found to be effective as a Po depressant (both hexagonal and monoclinic Po) on this challenging ore. Overall, the DETA/SMBS with concentrate regrind exhibited the best results (∼11 % Po recovery at ∼85 % Pn recovery) and was found to be sufficient in achieving the outlined targets.
Systematic literature review of sentiment analysis on Twitter using soft computing techniques
Authors: Kumar Akshi , Jaiswal Arunima 
Published: January 2019

SummarySentiment detection and classification is the latest fad for social analytics on Web. With the array of practical applications in healthcare, finance, media, consumer markets, and government, distilling the voice of public to gain insight to target information and reviews is non‐trivial. With a marked increase in the size, subjectivity, and diversity of social web‐data, the vagueness, uncertainty and imprecision within the information has increased manifold. Soft computing techniques have been used to handle this fuzziness in practical applications. This work is a study to understand the feasibility, scope and relevance of this alliance of using Soft computing techniques for sentiment analysis on Twitter. We present a systematic literature review to collate, explore, understand and analyze the efforts and trends in a well‐structured manner to identify research gaps defining the future prospects of this coupling. The contribution of this paper is significant because firstly the primary focus is to study and evaluate the use of soft computing techniques for sentiment analysis on Twitter and secondly as compared to the previous reviews we adopt a systematic approach to identify, gather empirical evidence, interpret results, critically analyze, and integrate the findings of all relevant high‐quality studies to address specific research questions pertaining to the defined research domain.
Novel and Versatile Cobalt Azobenzene‐Based Metal‐Organic Framework as Hydrogen Adsorbent
Authors: Montes‐Andrés Helena , Leo Pedro , Orcajo Gisela , Rodríguez‐Diéguez Antonio , Choquesillo‐Lazarte Duane , Martos Carmen , Botas Juan Ángel , Martínez Fernando , Calleja Guillermo 
Published: January 2019

AbstractA novel URJC‐3 material based on cobalt and 5,5′‐(diazene‐1,2‐diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC‐3, with polyhedral morphology, crystallizes in the tetragonal and P43212 space group, exhibiting a three‐dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC‐3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single‐walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.
Photoswitchable Host‐Guest Systems Incorporating Hemithioindigo and Spiropyran Units
Authors: Moncelsi Giulia , Ballester Pablo 
Published: January 2019

AbstractWe cover selected examples of the incorporation of hemithioindigo and spiropyran units in one of the binding partners of synthetic host‐guest systems. In the simplest systems, the isomerization of the switch simply modulates the thermodynamic stability of the resulting isomeric host‐guest complexes. The presence of more than two binding partners constitute multicomponent host‐guest systems. In some of them, the isomerization of the molecular switch alters the composition of the system producing a shuttling process of one of the components between different hosts. In others, the isomerization process controls the uptake and release of some of the components from/to the bulk solution. We show that the understanding of the isomerization mechanisms of the molecular switches and the effects produced by the external stimuli are essential for the design of complex and responsive supramolecular host‐guest systems. The physicochemical properties of the hemithioindigo and spiropyran molecular photoswitches are complementary, providing different avenues to their applications in solution and material science.
Paradoxical tensions and corporate sustainability: A focus on circular economy business cases
Authors: Daddi Tiberio , Ceglia Domenico , Bianchi Guia , de Barcellos Marcia Dutra 
Published: January 2019

AbstractThe paradoxical tensions in corporate sustainability is hotly debated in the literature. Some authors have underlined the need for empirical works in this field, and the circular economy could help to bridge this gap. The circular economy creates contrasting challenges for companies, which lead to paradoxical tensions. On the one hand, companies pursue circular economy goals—such as the use of recycled raw materials—thus highlighting their environmental commitment. On the other hand, such usage may affect the quality and consequently the competitiveness of products. Our study investigates the acknowledgement of these tensions and the strategies adopted by companies to manage them. Using a multiple case study approach, we focus on an Italian sample of three manufacturing sectors: paper production, textile/clothing, and leather. The results show the different defensive and proactive strategies adopted by firms highlighting, in one case, a relevant opportunity exploited by a company considered in the sample. Our paper contributes to the existing knowledge on paradoxical tensions management in companies involved in corporate sustainability inviting scholars towards new research avenues focused on circular economy.
Multifunctional and Sustainable Fe‐Iminopyridine Complexes for the Synthesis of Cyclic Carbonates
Authors: Seong Eun Young , Kim Jae Hyung , Kim Nam Hee , Ahn Kwang‐Hyun , Kang Eun Joo 
Published: January 2019

AbstractThe use of multifunctional and sustainable Fe catalysts for the formation of cyclic carbonates from epoxides and carbon dioxide at 80 °C and 3 bar pressure is presented. The optimal catalyst possesses a halide counteranion and a hydrogen bond donor to activate the epoxide for ring opening, affording a single‐component, cocatalyst‐free catalytic system.
Insect pest control, approximate dynamic programming, and the management of the evolution of resistance
Authors: Hackett Sean C. , Bonsall Michael B. 
Published: January 2019

AbstractEcological decision problems, such as those encountered in agriculture, often require managing conflicts between short‐term costs and long‐term benefits. Dynamic programming is an ideal method for optimally solving such problems but agricultural problems are often subject to additional complexities that produce state spaces intractable to exact solutions. In contrast, look‐ahead policies, a class of approximate dynamic programming (ADP) algorithm, may attempt to solve problems of arbitrary magnitude. However, these algorithms focus on a temporally truncated caricature of the full decision problem over a defined planning horizon and as such are not guaranteed to suggest optimal actions. Thus, look‐ahead policies may offer promising means of addressing detail‐rich ecological decision problems but may not be capable of fully utilizing the information available to them, especially in scenarios where the best short‐ and long‐term solutions may differ. We constructed and applied look‐ahead policies to the management of a hypothetical, stage‐structured, continually reproducing, agricultural insect pest. The management objective was to minimize the combined costs of management actions and crop damage over a 16‐week growing season. The manager could elect to utilize insecticidal sprays or one of six release ratios of male‐selecting transgenic insects where the release ratio determines the number of transgenic insects to be released for each wild‐type male insect in the population. Complicating matters was the expression of insecticide resistance at non‐trivial frequencies in the pest population. We assessed the extent to which look‐ahead policies were able to recognize the potential threat of insecticide resistance and successfully integrate insecticides and transgenic releases to capitalize upon their respective benefits. Look‐ahead policies were competent at anticipating and responding to ecological and economic information. Policies with longer planning horizons made fewer, better‐timed insecticidal sprays and made more frequent transgenic releases, which consequently facilitated lower resistance allele frequencies. However, look‐ahead policies were ultimately inefficient resistance managers, and directly responded to resistance only when it was dominant and prevalent. Effective long‐term agricultural management requires the capacity to anticipate and respond to the evolution of resistance. Look‐ahead policies can accommodate all the information pertinent to making the best long‐term decision but may lack the perspective to actually do so.
Consumer trophic positions respond variably to seasonally fluctuating environments
Authors: McMeans Bailey C. , Kadoya Taku , Pool Thomas K. , Holtgrieve Gordon W. , Lek Sovan , Kong Heng , Winemiller Kirk , Elliott Vittoria , Rooney Neil , Laffaille Pascal , McCann Kevin S. 
Published: January 2019

AbstractThe effects of environmental seasonality on food web structure have been notoriously understudied in empirical ecology. Here, we focus on seasonal changes in one key attribute of a food web, consumer trophic position. We ask whether fishes inhabiting tropical river–floodplain ecosystems behave as seasonal omnivores, by shifting their trophic positions in relation to the annual flood pulse, or whether they feed at the same trophic position all year, as much empirical work implicitly assumes. Using dietary data from the Tonle Sap Lake, Cambodia, and a literature review, we find evidence that some fishes, especially small piscivores, increased consumption of invertebrates and/or plant material during the wet season, as predicted. However, nitrogen stable isotope (δ15N) data for 26 Tonle Sap fishes, spanning a broader range of functional groups, uncovered high variation in seasonal trophic position responses among species (0 to ±0.52 trophic positions). Based on these findings, species respond to the flood pulse differently. Diverse behavioral responses to seasonality, underpinned by spatiotemporal variation at multiple scales, could be central for rerouting matter and energy flow in these dynamic ecosystems. Seasonally flexible foraging behaviors warrant further study given their potential influence on food web dynamics in a range of fluctuating environments.
Key colonist pools and habitat filters mediate the composition of fiddler crab–associated bacterial communities
Authors: Cuellar‐Gempeler Catalina , Leibold Mathew A. 
Published: January 2019

Abstract
The diversity and composition of local communities depends strongly on the pool of species that have been able to colonize that community from elsewhere. Typically this is thought to depend on a larger regional species pool that is subject to local environmental constraints that act as “filters.” Often, however, colonists arrive from multiple sources that differ in habitat conditions and have therefore already experienced distinct “prefiltering.” Consequently, it is the interaction of species from these distinct pools that determine the composition of local communities. This interaction is particularly important when certain colonist pools provide keystone species with disproportionate roles on community assembly. We propose to identify these key colonist pools and their interaction with local habitat filters by quantifying community‐level responses to colonist pool manipulation. We tested this framework to assess the contribution of surface and burrow sediment bacteria to bacterial communities associated with the fiddler crab, Uca panacea. In a mesocosm experiment, we combined normal and autoclaved surface and burrow sediment in a factorial experimental design, and we evaluated the community‐level responses of carapace and gut microbial assemblages to sediment treatments with next‐generation sequencing of the 16S rRNA gene. Results from carapace bacterial communities indicate that burrow sediments contribute most recruits, but surface sediments provide a few key colonizers that become established in the carapace community. In contrast, the composition of gut‐associated microbial communities responded only to surface bacteria manipulation, despite being highly dissimilar from the community composition in both the surface and burrow source pools. These results suggest that assembly in the gut depends primarily on colonization from the surface sediment and regulation by habitat filtering. For fiddler crab–associated bacteria, we can conclude that key colonist pools and habitat filters regulate the influence of multiple colonist pools. Incorporating and distinguishing the contribution of multiple sources of species, rather than a single regional species pool, may better explain community dynamics in many systems, especially those with weak habitat filters.
Prediction of incident heart failure by serum amino‐terminal pro‐B‐type natriuretic peptide level in a community‐based cohort
Authors: Campbell Duncan J. , Gong Fei Fei , Jelinek Michael V. , Castro Julian M. , Coller Jennifer M. , McGrady Michele , Boffa Umberto , Shiel Louise , Wang Bing H. , Liew Danny , Wolfe Rory , Stewart Simon , Owen Alice J. , Krum Henry , Reid Christopher M. , Prior David L. 
Published: January 2019

AimsWe investigated which serum amino‐terminal pro‐B‐type‐natriuretic peptide (NT‐proBNP) levels inform heart failure (HF) risk in a community‐based population at increased cardiovascular disease (CVD) risk.Methods and resultsInclusion criteria were age ≥ 60 years with one or more of self‐reported hypertension, diabetes, heart disease, abnormal heart rhythm, cerebrovascular disease, or renal impairment. Exclusion criteria were known HF, ejection fraction (EF) < 50%, or more than mild valve abnormality. NT‐proBNP levels were measured in 3842 participants on enrolment. HF was diagnosed in 162 participants at a median of 4.5 (interquartile range 2.7–5.4) years after enrolment, 73 with HF with preserved EF (HFpEF), 53 with HF with reduced EF (HFrEF), and 36 with valvular HF (VHF). Areas under the receiver operating characteristic curve (AUC) for 5‐year prediction of total HF were similar for NT‐proBNP alone (0.79, 95% confidence interval 0.74–0.83) and a 7‐parameter multivariable model (0.82, 0.77–0.86, P = 0.035). NT‐proBNP cut‐points of 11, 16, and 25 pmol/L for individuals aged 60–69, 70–79, and ≥ 80 years, respectively, achieved sensitivities > 76% and specificities of 47–69% for 5‐year prediction of total HF in men and women in all three age groups. Sensitivities were ≥ 75% in most subgroups according to body mass index, estimated glomerular filtration rate, and the presence or absence of atrial fibrillation, pacemaker, or CVD, and for the prediction of HFpEF, HFrEF and VHF.ConclusionAge‐specific serum NT‐proBNP levels inform prognosis, and hence therapeutic decisions, regarding HF risk in individuals at increased CVD risk.
Application of HVSR to estimating thickness of laterite weathering profiles in basalt
Authors: Nelson Stephen , McBride John 
Published: January 2019

AbstractLateritic weathering profiles (LWPs) are widespread in the tropics and comprise an important component of the Critical Zone (CZ). The Hawaiian Islands make an excellent natural laboratory for examining the tropical CZ, where the bedrock composition (basalt) is nearly uniform and rainfall varies greatly. This natural laboratory is employed to assess the utility of the HVSR (horizontal/vertical spectral ratio) method to characterize the shear‐wave velocity (Vs) structure of LWPs, particularly the depth to the contact between saprolite and basalt bedrock.LWP thicknesses determined from HVSR provide good agreement with multi‐channel analysis of surface waves (MASW) profiles, well logs and outcrop. LWP thicknesses may be estimated from the fundamental mode equation or through forward models. Prior knowledge about the subsurface from well, outcrop, and MASW profiles may greatly aid modeling in some cases. For the 3.2 to 1.8 Ma Koolau Volcano on Oahu, the downward rate of advance of the weathering front varies from 0.004 to 0.041 m/ka. For the 0.44 to 0.10 Ma Kohala Volcano (Big Island of Hawaii) rates vary from 0.013 to 0.047 m/ka.Simple H/V spectra develop in areas where the combined effects of time and elevated rainfall produce thick LWPs with a flat base and a general absence of core stones with an ideal layered geometry. Abundant buried core stones violate the assumption of simple layered geometries and scatter acoustic energy, leading to uninterpretable results. This is common where low rainfall and a young basaltic substrate leave abundant core stones as well as an undulating contact between saprolite and bedrock. Velocity inversions (high Vs intervals within low Vs saprolite) may also be present and originate from relatively intact bedrock horizons or mineralogical changes within saprolite. At Kohala, a gibbsite‐rich horizon produces such a velocity inversion due to enhanced weathering and subsequent collapse of saprolite in a discrete horizon. © 2019 John Wiley & Sons, Ltd.
Different organophosphate flame retardant and metabolite concentrations in urine from male and female university students in Beijing and an assessment of exposure via indoor dust
Authors: Li Junqi , Dong Zheng , Wang Ying , Bao Junsong , Yan Yijun , Jin Jun 
Published: January 2019

Abstract

Organophosphate flame retardants (OPFRs) have been found in human samples and associated with adverse health effects. In the present study, OPFR and dialkyl and diaryl phosphate (DAP) concentrations in human urine were determined and differences in the concentrations in urine from males and females were investigated. Urine samples from 22 male and 26 female university students, paired dust samples from the dormitories (13 each for males and females), and 10 dust samples from university teaching buildings were analyzed. The tri-o-cresyl phosphate (TOCP), tri-p-cresyl phosphate (TPCP), and tris(2-chloroisopropyl)phosphate (TCIPP) concentrations were significantly higher (p = 0.049, 0.023, and 0.027, respectively) in urine from the female students than in urine from the male students. Similar differences were found between males and females in terms of OPFR exposure and OPFR concentrations in urine for three-fourths of the OPFRs. Questionnaire answers and calculations indicated that disparities in OPFR concentrations in urine were mainly caused by females spending much more time than males in dormitories. Organophosphate flame retardants may pose degrees of health risk similar to those of polybrominated diphenyl ethers (PBDEs), and this must be considered when making decisions about controlling flame retardants. We are not aware of any previous studies that simultaneously monitor OPFRs and DAPs in human urine in China. Environ Toxicol Chem 2019;38:760–768. © 2019 SETAC
Abstract
OPFR and metabolite concentrations in urine from university students and its association with indoor dust.