bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalyst Optimisation for Asymmetric Synthesis by Ligand Chirality Element Addition: A Perspective on Stereochemical Cooperativity
Authors: Richards Christopher J. , Arthurs Ross A. 
Published: April 2017

AbstractThe concept of matched and mismatched stereochemical pairings has been utilised extensively in organic synthesis, with the cooperativity resulting from the former enabling many reactions to proceed with high stereoselectivity. This approach was first developed to improve the diastereoselectivity of a reaction by matching the configuration of an enantiopure reagent or catalyst with the configuration of an enantiopure substrate. It has been extended to the asymmetric transformation of prochiral substrates controlled by reagents and catalysts containing two or more stereogenic centres. Matched and mismatched pairings may again be identified, with the former resulting in higher product enantioselectivity. This Minireview examines stereochemical pairings within catalysts generated from the combination of a metal with an enantiopure ligand; specifically examples in which the ligand diastereoisomers examined for cooperativity are formally the result of the addition of a chiral element to an existing enantiopure ligand. Comparison of all three ligands in each of the fifty‐six examples examined reveals that, in the majority of cases, the added element of chirality increases and decreases the enantioselectivity with respect to the parent ligand. The iterative application of this effect offers a potentially powerful method for catalyst optimisation for use in asymmetric synthesis.
An efficient and enantioselective Michael addition of aromatic oximes to α,β‐unsaturated aldehydes promoted by a chiral diamine catalyst derived from α,α‐diphenyl prolinol
Authors: Chen Feng , Ren Hong‐Xia , Yang Yu , Ji Shan‐Ping , Zhang Zheng‐Bing , Tian Fang , Peng Lin , Wang Li‐Xin 
Published: April 2017

AbstractChiral diamine catalysts 11a–e derived from α,α‐diphenyl prolinol were prepared and successfully applied to the Michael addition of aromatic oximes to α,β‐unsaturated aldehydes in mediocre to good yields (up to 78%) and good to high enantioselectivities (up to 93% ee).
CORRELATION BETWEEN EMISSION INTENSITIES IN DAYSIDE AURORAL ARCS AND PRECIPITATING ELECTRON SPECTRA
Authors: Qi QIU , Hui‐Gen YANG , Quan‐Ming LU , Ze‐Jun HU 
Published: April 2017

AbstractMore than 20000 dayside auroral arcs of the 557.7 and 630.0 nm emission intensities have been statistically studied, and the dependences of the I557.7/I630.0 ratio on the I557.7 emission intensity have been determined. The 557.7 nm emission intensity has two maximum values in the hot spot and warm spot regions, with average values of 2.2 and 2.9 kR, respectively. But there is a maximum near magnetic noon for 630.0 nm emission intensity, with an average value of 1.5 kR. In the I557.7 emission range 0.1∼10 kR, the I557.7/I630.0 ratio tends to increase from 0.2 to 9. The correlation between emission intensity and precipitating electron spectra has been investigated using 17 cases of DMSP passing through 40 auroral arcs above Chinese Arctic Yellow River Station (YRS). We obtain the equations that the average energy of the electrons is proportional to the I557.7/I630.0 ratio. There is a positive correlation between the total energy flux of the electrons and the I557.7 emission intensity. The typical region of electron precipitation, where the auroral arcs were observed, was the boundary plasma sheet (BPS) in the prenoon and postnoon sectors. We also found some low‐energy precipitating electrons from the region of mantle, where the arcs are located poleward of dayside auroral oval. The magnetic source region of the precipitating electrons with low energy was identified as the low latitude boundary layer (LLBL) adjacent to magnetic noon. Arcs are located in the lower latitude in this region.
Cannabinoid Type 1 Receptor (CB1) Ligands with Therapeutic Potential for Withdrawal Syndrome in Chemical Dependents of Cannabis sativa
Authors: Ferreira Jaderson V. , Chaves Gisele A. , Marino Bianca L. B. , Sousa Kessia P. A. , Souza Lucilene R. , Brito Maiara F. B. , Teixeira Hueldem R. C. , da Silva Carlos H. T. P. , Santos Cleydson B. R. , Hage‐Melim Lorane I. S. 
Published: April 2017

AbstractCannabis sativa withdrawal syndrome is characterized mainly by psychological symptoms. By using computational tools, the aim of this study was to propose drug candidates for treating withdrawal syndrome based on the natural ligands of the cannabinoid type 1 receptor (CB1). One compound in particular, 2‐n‐butyl‐5‐n‐pentylbenzene‐1,3‐diol (ZINC1730183, also known as stemphol), showed positive predictions as a human CB1 ligand and for facile synthetic accessibility. Therefore, ZINC1730183 is a favorable candidate scaffold for further research into pharmacotherapeutic alternatives to treat C. sativa withdrawal syndrome.
A Multitarget Approach toward the Development of 8‐Substituted Purines for Photoprotection and Prevention of UV‐Related Damage
Authors: Djuidje Ernestine N. , Dissette Valeria , Bino Alessia , Benetti Simonetta , Balzarini Jan , Liekens Sandra , Manfredini Stefano , Vertuani Silvia , Baldisserotto Anna 
Published: April 2017

AbstractUltraviolet (UV) light is the most abundant and significant modifiable risk factor for skin cancer and many other skin diseases such as early photo‐aging. Across the solar radiation spectrum, UV light is the main cause behind skin problems. In the search for novel photoprotective compounds, a new series of 8‐substituted purines were synthesized from commercially available 6‐hydroxy‐4,5‐diaminopyrimidine hemisulfate or 4,5‐diaminopyrimidine. All title compounds were investigated for their UV filtering, antioxidant, antifungal, and antiproliferative activities. For the photoprotection assays we used a diffuse transmittance technique to determine the sun protection factor (SPF) in vitro, and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and ferric ion reducing antioxidant power (FRAP) tests for evaluating the antioxidant activity of the more potent compounds. Among them, 8‐(2,5‐dihydroxyphenyl)‐7H‐purin‐6‐ol (compound 26) proved to be a good radical scavenger and is also endowed with broad‐spectrum UVA filtering capabilities, suitable for further development as a protective molecule.
Influence of Divalent Counterions on the Dynamics in DNA as Probed by Using a Minor‐Groove Binder
Authors: Paul Sneha , Ahmed Tasnim , Samanta Anunay 
Published: April 2017

AbstractDNA dynamics, to which water, counterions, and DNA motions contribute, is a topic of considerable interest because it is closely related to the efficiency of biological functions performed by it. Simulation studies and experiments suggest that the counterion dynamics in DNA probed by a minor‐groove binder are similar for various monovalent counterions. To date, the influence on DNA dynamics of higher‐valence counterions, which are also present around DNA and are known to bind more strongly to it than monovalent ions, has not been studied. Herein we investigated DNA dynamics in the presence of Mg2+ and Ca2+, chosen for their relative abundance in cells, by using minor‐groove binder 4′,6‐diamidino‐2‐phenylindole (DAPI) as a fluorescence probe. The dynamics, as measured from the time‐resolved fluorescence Stokes shifts of DAPI bound to calf thymus DNA on a subpicosecond‐to‐nanosecond timescale, were found to be very similar in the presence of both the divalent ions and Na+ ions. The observation is explained by considering the screening of the electric field of the divalent ion by its hydration shell, preferential binding of the ions to the phosphate groups, and displacement of ions from the minor groove by DAPI due to the stronger binding interaction of the latter. Furthermore, the similarity of our results in the presence of Na+ to those reported for smaller oligonucleotides suggests that the chain length of DNA does not influence the DNA dynamics.
The Significance of Corporate Social Disclosure for High‐Tech Manufacturing Companies: Focus on Employee and Community Aspects of Sustainable Development
Authors: Lawal Emmanuel , May Gökan , Stahl Bojan 
Published: April 2017

AbstractAddressing a global key sector area – the high technology manufacturing sector – we examine if there is truly a benefit of corporate social disclosure to the bottom line of organizations within this sector and if stakeholders should devote more attention to this strategic topic. Accordingly, we assess the potential effects of corporate social disclosure on financial performance, with a particular focus on employee and community aspects. This effect is examined for a sample of 405 companies operating within the sector. Additionally, we posit that the innovative nature of the sector adds a sub‐plot and possibly exaggerates the effect of corporate social disclosure on financial performance. The study offers guidance to stakeholders on how actions in the CSR realm may potentially affect company performance within this sector, as well as providing direction on the impact improved disclosure can have on financial performance. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment
Board Structure to Enhance Social Responsibility Development: A Qualitative Comparative Analysis of US Companies
Authors: Cuadrado‐Ballesteros Beatriz , Martínez‐Ferrero Jennifer , García‐Sánchez Isabel M. 
Published: April 2017

AbstractThis study adds clarity to inconclusive results in previous literature about the link between board characteristics and the level of social responsibility performance by using fuzzy set qualitative comparative analysis. Specifically, we propose a new holistic framework based on the complexity theory. From a sample of 471 non‐financial companies from the USA for the period 2008–2010, our findings support the four tenets of complexity theory: equifinality, complexity, asymmetry, and causal asymmetry. More concretely, they suggest that CSR performance depends on a complex configuration of some board characteristics, such as size, independency, diversity and activity, and other corporate attributes (i.e., company size, leverage, and growth opportunities). These factors play a key role as the ingredients of the recipe and, in a proper combination, contribute to obtaining high levels of social responsibility performance. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment
Host sympatry and body size influence parasite straggling rate in a highly connected multihost, multiparasite system
Authors: Rivera‐Parra Jose L. , Levin Iris I. , Johnson Kevin P. , Parker Patricia G. 
Published: April 2017

AbstractParasite lineages commonly diverge when host lineages diverge. However, when large clades of hosts and parasites are analyzed, some cases suggest host switching as another major diversification mechanism. The first step in host switching is the appearance of a parasite on an atypical host, or “straggling.” We analyze the conditions associated with straggling events. We use five species of colonially nesting seabirds from the Galapagos Archipelago and two genera of highly specific ectoparasitic lice to examine host switching. We use both genetic and morphological identification of lice, together with measurements of spatial distribution of hosts in mixed breeding colonies, to test: (1) effects of local host community composition on straggling parasite identity; (2) effects of relative host density within a mixed colony on straggling frequency and parasite species identity; and (3) how straggling rates are influenced by the specifics of louse attachment. Finally, we determine whether there is evidence of breeding in cases where straggling adult lice were found, which may indicate a shift from straggling to the initial stages of host switching. We analyzed more than 5,000 parasite individuals and found that only ~1% of lice could be considered stragglers, with ~5% of 436 host individuals having straggling parasites. We found that the presence of the typical host and recipient host in the same locality influenced straggling. Additionally, parasites most likely to be found on alternate hosts are those that are smaller than the typical parasite of that host, implying that the ability of lice to attach to the host might limit host switching. Given that lice generally follow Harrison's rule, with larger parasites on larger hosts, parasites infecting the larger host species are less likely to successfully colonize smaller host species. Moreover, our study supports the general perception that successful colonization of a novel host is extremely rare, as we found only one nymph of a straggling species, which may indicate successful reproduction.
Flowering time evolution is independent of serpentine tolerance in the California flora
Authors: Schneider Adam 
Published: April 2017

AbstractComparative phylogenetic tests have been only recently applied to the many hypotheses about the role ultramafic (serpentine) soils play in the evolution and ecology of regional floras. An association between serpentine tolerance and early flowering has been observed at microevolutionary scales but not yet tested broadly across angiosperms. I used both hypothesis testing (phylogenetically independent contrasts) and model‐selection approaches to compare published data of serpentine tolerance with flowering time using phylogenetic trees representing 24 clades of plants representing 27 genera and 17 families. A total of 126 independent contrasts revealed no significant difference in flowering times across all clades or within any one clade except for the Thelypodieae, in which flowering time of serpentine‐tolerant lineages was later. Similarly, an Ornstein‐Uhlenbeck model with one optimal flowering time was preferred over a model with separate optima depending on serpentine tolerance in nearly all genera. A phylogenetically un‐corrected ANOVA found that serpentine‐tolerant species have an earlier distribution of flowering times compared to both endemic and non‐tolerant species, and median flowering times of non‐tolerant species show a bimodal distribution. Therefore, I conclude that the long‐term evolutionary responses of flowering time in a lineage that becomes tolerant of serpentine are variable across genera, with no significant overall bias toward earlier or later flowering. However, given that close relatives of serpentine‐tolerant lineages tend to also flower relatively early, early flowering time may serve as an exaptation for serpentine tolerance. In combination with previously published ecotype studies, these results illustrate the eco‐evolutionary scale dependence of flowering time.
Taxonomic and functional assessment of mesopredator diversity across an estuarine habitat mosaic
Authors: Gross Collin , Donoghue Cinde , Pruitt Casey , Trimble Alan C. , Ruesink Jennifer L. 
Published: April 2017

AbstractA long‐standing rule in ecology is that structural complexity increases abundance and diversity of organisms, but this paradigm glosses over potential trait‐specific benefits of habitat structure across different regional species pools. We tested this idea using multiple response variables emphasizing taxonomic and functional diversity in seagrass‐vegetated, edge, and unvegetated habitats across three estuaries in Washington State (USA). We also used these variables in tandem to evaluate functional redundancy as a proxy for ecosystem resistance and resilience. The estuaries spanned a twofold range in richness of mesopredatory fishes and decapods. Increases in per‐sample abundance with habitat structure were confined to three of seven functional groups, specifically those occupying the water column or directly associated with seagrass shoots. Consequently, seagrass reduced mesopredator diversity by reducing evenness. Habitats differed in mesopredator assemblages despite their spatial proximity (~3 m), supported by multivariate analyses performed at functional and taxonomic resolutions, but site differences were less apparent functionally than taxonomically. Functional redundancy did not differ by habitat, but increased with the richness of the regional species pool. Edge habitats were generally intermediate in community structure, per‐sample abundance, and diversity between seagrass and unvegetated habitats. Structural complexity provided a trait‐specific enhancement of abundance, and this pattern applied across species pools. Because seagrass benefits species with certain traits, management focused on the low‐intertidal estuarine habitat mosaic, rather than a particular habitat type, and on places where redundancy is already low, best supports mesopredator diversity and function.
A new approach to estimate fecundity rate from inter‐birth intervals
Authors: Arso Civil Mònica , Cheney Barbara , Quick Nicola J. , Thompson Paul M. , Hammond Philip S. 
Published: April 2017

AbstractAccurate estimates of fecundity rate are key to population assessments and effectively direct conservation efforts. We present a new approach to estimate fecundity rate based on the probability of a female giving birth, conditional on a previous birth t years ago, from which an expected inter‐birth interval (IBI) can be estimated. We use generalized linear mixed‐effects models to account for individual and temporal variability and apply the approach to individual reproductive histories of bottlenose dolphins (Tursiops truncatus) from the east coast of Scotland. We estimate a fecundity rate of 0.222 (95% CI = 0.218–0.253) and an expected IBI of 4.49 yr (95% CI = 3.94–4.93 yr). We use simulated data samples to show that the approach produces estimates with a minimum bias of <3%. Simulations are also used to investigate the effect of the most common data‐driven biases in the estimates of birth intervals and fecundity rate; we recommend longitudinal studies of at least 10 yr and capture probabilities of at least 0.3 when using this methodology. The approach may be modified to incorporate other parameters of interest and should be applicable to any population with comprehensive data on birth intervals.
Stress and subsidy effects of seagrass wrack duration, frequency, and magnitude on salt marsh community structure
Authors: Hanley Torrance C. , Kimbro David L. , Hughes Anne Randall 
Published: April 2017

AbstractEnvironmental perturbations can strongly affect community processes and ecosystem functions by acting primarily as a subsidy that increases productivity, a stress that decreases productivity, or both, with the predominant effect potentially shifting from subsidy to stress as the overall intensity of the perturbation increases. While perturbations are often considered along a single axis of intensity, they consist of multiple components (e.g., magnitude, frequency, and duration) that may not have equivalent stress and/or subsidy effects. Thus, different combinations of perturbation components may elicit community and ecosystem responses that differ in strength and/or direction (i.e., stress or subsidy) even if they reflect a similar overall perturbation intensity. To assess the independent and interactive effects of perturbation components, we experimentally manipulated the magnitude, frequency, and duration of wrack deposition, a common stress‐subsidy in a variety of coastal systems. The effects of wrack perturbation on salt marsh community and ecosystem properties were assessed both in the short‐term (at the end of a 12‐week experimental manipulation) and long‐term (6 months after the end of the experiment). In the short‐term, plants and associated benthic invertebrates exhibited primarily stress‐based responses to wrack perturbation. The extent of these stress effects on density of the dominant plant Spartina alterniflora, total plant percent cover, invertebrate abundance, and sediment oxygen availability were largely determined by perturbation duration. Yet, higher nitrogen content of Spartina, which indicates a subsidy effect of wrack, was influenced primarily by perturbation magnitude in the short‐term. In the longer term, perturbation magnitude determined the extent of both stress and subsidy effects of wrack perturbation, with lower subordinate plant percent cover and snail density, and higher Spartina nitrogen content in high wrack biomass treatments. However, stress effects on the marsh community were generally less pronounced 6 months after the wrack perturbation, indicating capacity for recovery. Our results demonstrate that individual perturbation components can determine the degree to which its effects on the community elicit primarily stress‐ and/or subsidy‐based responses. Further, the nature and extent of stress‐subsidy effects can change over time, depending on species’ relative ability to tolerate and/or recover from perturbation.
Plant‐soil feedbacks in declining forests: implications for species coexistence
Authors: Gómez‐Aparicio Lorena , Domínguez‐Begines Jara , Kardol Paul , Ávila José M. , Ibáñez Beatriz , García Luis V. 
Published: April 2017

AbstractPlant‐soil feedbacks (PSFs) play a relevant role as drivers of species abundance, coexistence, and succession in plant communities. However, the potential contribution of PSFs to community dynamics in changing forest ecosystems affected by global change drivers is still largely unexplored. We measured the direction, strength and nature (biological vs. chemical) of PSFs experienced by coexisting tree species in two types of declining Quercus suber forests of southwestern Spain (open woodland vs. closed forest) invaded by the exotic soil pathogen Phytophthora cinnamomi. To test PSFs in a realistic community context, we focused not only on individual PSFs (i.e., comparing the growth of a tree species on conspecific vs. heterospecific soil) but also calculated net‐pairwise PSFs by comparing performance of coexisting tree species on their own and each other's soils. We hypothesized that the decline and death of Q. suber would alter the direction and strength of individual and net‐pairwise PSFs due to the associated changes in soil nutrients and microbial communities, with implications for recruitment dynamics and species coexistence. In support of our hypothesis, we found that the decline of Q. suber translated into substantial alterations of individual and net‐pairwise PSFs, which shifted from mostly neutral to significantly positive or negative, depending on the forest type. In both cases however the identified PSFs benefited other species more than Q. suber (i.e., heterospecific positive PSF in the open woodland, conspecific negative PSF in the closed forest). Our results supported PSFs driven by changes in chemical soil properties (mainly phosphorus) and arbuscular mycorrhizal fungi, but not in pathogen abundance. Overall, our study suggests that PSFs might reinforce the loss of dominance of Q. suber in declining forests invaded by P. cinnamomi by promoting the relative performance of non‐declining coexisting species. More generally, our results indicate an increase in the strength of net PSFs as natural forests become disturbed by global change drivers (e.g., invasive species), suggesting an increasingly important role of PSFs in forest community dynamics in the near future.
Development of Magnetic Levitation System for Science and Technology Education: Magnetic Levitation Control by Using a Hall Element Displacement Sensor with Neural Network
Authors: ASATO KENTARO , TERUYA KOHMEI , NAGADO TSUTOMU , TAMAKI SHIRO 
Published: April 2017

SUMMARYIn this study, we developed a magnetic levitation system using a Hall element displacement sensor with neural network for science and technology education. The sensor configured with three Hall elements was devised in order to measure displacement from an electromagnet to a levitated object with a permanent magnet. Use of the Hall element displacement sensor achieves a lower cost magnetic levitation system. Furthermore, three‐layered feedforward neural network was utilized in order to improve the precision of the Hall element displacement sensor. Finally, operation verification of the developed magnetic levitation system was conducted by designing state feedback regulator with observer.