bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Synthetically Versatile Pyridylidene Amide Ligands for Efficient Iridium‐Catalyzed Water Oxidation
Authors: Navarro Miquel , Smith Christene A. , Li Mo , Bernhard Stefan , Albrecht Martin 
Published: February 2018

AbstractThe synthetic versatility of pyridylidene amide (PYA) ligands has been exploited to prepare and evaluate a diverging series of iridium complexes containing C,N‐bidentate chelating aryl‐PYA ligands for water oxidation catalysis. The phenyl‐PYA lead structure 1 was modified (i) electronically through introduction of one, two, or three electron‐donating methoxy substituents on the aryl ring, (ii) by incorporating long aliphatic chains to the pyridyl fragment of the PYA unit, and (iii) by altering the PYA positions from para‐PYA to its ortho‐ and meta‐isomers. Electrochemistry indicated no substantial electronic effect of the aliphatic chains, and only minor changes of the electron density at iridium when modifying the aryl ligand site, yet substantial alteration if the PYA ligand is the ortho‐ (E1/2=+0.72 V), para‐ (E1/2=+0.64 V), or meta‐isomer (E1/2=+0.56 V vs. saturated calomel electrode; SCE). In water oxidation catalysis, the long alkyl chains did not induce any rate enhancement compared with the phenyl‐PYA lead compound, whereas MeO groups incorporated in the aryl group enhanced the catalytic activity from a turnover frequency (TOFmax)=1600 h−1 in the original Ph‐PYA system gradually as more MeO groups were introduced up to a TOFmax=3300 h−1 for a tris(MeO)‐substituted aryl‐PYA system. The variation of the PYA substitution had only a minor impact on catalytic activity and revealed only a weak trend in the sequence ortho>meta>para. The high activity of the tris(MeO) system and the ortho‐PYA isomer were attributed to efficient hydrogen bonding, which assists O−H bond activation and proton transfer. Remarkably, merging of the two optimized motifs, that is, an aryl unit with three MeO substituents and the PYA as the ortho isomer, into a single new aryl‐PYA ligand system failed to improve the catalytic activity. Computational analysis suggests too much congestion at the active site, which hinders catalytic turnover. These results illustrate the complexity of ligand design and the subtle effects at play in water oxidation catalysis.
12‐Vertex Zwitterionic Bis‐phosphonium‐nido‐carborates through Ring‐Opening Reactions of 1,2‐Diphosphetanes
Authors: Schulz Jan , Kreienbrink Anika , Coburger Peter , Schwarze Benedikt , Grell Toni , Lönnecke Peter , Hey‐Hawkins Evamarie 
Published: February 2018

AbstractCarborane‐substituted 1,2‐diphosphetanes (Ia,b) react with elemental lithium in THF with cleavage of the P−P bond to give a deep red solution from which, in the case of Ia, red crystals of a lithiated intermediate, [{1‐Li(THF)PtBu‐6‐PtBu‐4,1,6‐closo‐Li(THF)C2B10H10}{Li(THF)3}]2⋅2 THF (2 a), are obtained. The compound is dimeric, C2‐symmetric and contains six lithium and four phosphorus atoms. Two lithium atoms cap the six‐membered C2B4 faces, resulting in two 13‐vertex closo‐clusters (according to Wade's rules) with docosahedral geometry. The addition of methyl iodide resulted in the formation of zwitterionic bis‐phosphonium‐nido‐carborates 7,10‐bis(tert‐butyldimethylphosphonium)dodecahydro‐7,10‐dicarba‐nido‐dodecaborate(2−) (1 a) and 7,10‐bis(N,N‐diisopropylaminodimethylphosphonium)dodecahydro‐7,10‐dicarba‐nido‐dodecaborate(2−) (1 b) in moderate to good yields. Compounds 1 a and 1 b exhibit short Ccluster−P bonds and large Ccluster⋅⋅⋅Ccluster distances in the solid state. Further insight into the ring opening and reduction potential of the alkyl halide was obtained from methylation reactions of different 1,2‐bis‐phosphinocarboranes. The reaction of rac‐/meso‐1,2‐bis(tert‐butylmethylphosphino)‐1,2‐dicarba‐closo‐dodecaborane(12) (3 a) with two equivalents of methyl iodide also resulted in the formation of 1 a (as shown by NMR spectroscopy), whereas the reaction of 1,2‐bis(diphenylphosphino)‐1,2‐dicarba‐closo‐dodecaborane(12) with methyl triflate afforded the phosphonium salt 1‐methyl‐diphenylphosphonium‐2‐diphenylphosphino‐1,2‐dicarba‐closo‐dodecaborane(12) triflate (4) without reduction of the cluster.
Self‐Assembly of a Guanosine Derivative To Form Nanostructures and Transmembrane Channels
Authors: Das Rabindra Nath , Kumar Y. Pavan , Kumar S. Arun , Schütte Ole Mathis , Steinem Claudia , Dash Jyotirmayee 
Published: February 2018

AbstractWe herein report the self‐assembly of a lipophilic bromoguanosine derivative (G1) in homogeneous solution, in the solid state and in planar bilayer membranes. The self‐assembly of G1, driven by H‐bonding and π–π stacking interactions can form different nano‐structures depending on incubation time. The G1 nanostructure is able to bind a bioactive dye like Rose Bengal. In crystal state, it shows ribbon type H‐bonding pattern and exhibits birefringence in polarized light. And further, the self‐assembled nanostructure of G1 can form discrete transmembrane ion channels in lipid bilayer membranes, enabling passage of potassium ions.
Cation‐Triggered Stannate(II)/Stannylenoid/Stannylene Conversion
Authors: Zhao Hui , Li Junxia , Xiao Xu‐Qiong , Kira Mitsuo , Li Zhifang , Müller Thomas 
Published: February 2018

AbstractThe reaction of dipotassio‐tetrasilan‐1,4‐diide (4) with anhydrous SnCl2 at low temperature results in the formation of a five‐membered cyclic potassio chlorostannate(II) ([(18‐C‐6)K](1)). By careful cation exchange reactions, it was transformed into the sodium chlorostannylenoid 2 (by using Na2[B12Cl12]) or into the non‐stabilized cyclic bissilylstannylene 3 (through applying Li[Al(OC(CF3)3)4]). The increasing Lewis basicity of the bissilylstannylene 3 was analyzed by combined methods of DFT calculations and NMR spectroscopy and substantiated by the synthesis of the corresponding iron carbonyl complexes 7 and 8 from the chlorostannate 1 and the stannylene 3, respectively.
Comprehensive investigation into the interconversion of C‐2 diastereomers of naringin
Authors: Yao Hongliang , Su Weiwei , Lin Linhuo , Pan Wenjun , Zeng Xuan , Li Panlin 
Published: February 2018

AbstractNaringin is a flavanone that widely presents on daily diet and traditional medicinal materials. The ratios of naringin C‐2 diastereomers are found different in reported samples, thus suspiciously leading to various functions. In this study, we measured the interconversion of C‐2 diastereomers intensively with ultimate high‐performance liquid chromatography and circular dichroism spectra. We examined the diastereomeric naringins in fresh citrus fruit, Huajuhong decoction pieces, and naringin tablet; evaluated the impact of tablet production procedures in factory; and monitored the rapid racemization in incubation. The results not only confirmed that enzyme, temperature, and pH condition could influence the interconversion but also demonstrated that diverse ratios of diastereomers showed limited influence on metabolic behaviors of naringin in the blood, which consequently cause comparable bioactivities. This study could provide comprehensive understanding of diastereomeric interconversion and provide useful reference for drug development.
ZIF‐based water‐stable mixed‐matrix membranes for effective CO2 separation from humid flue gas
Authors: Sarfraz Muhammad , Ba‐Shammakh M. 
Published: February 2018

AbstractWater stable mixed‐matrix membranes (MMMs) were developed to help control global warming by capturing and sequestrating carbon dioxide (CO2) from humid flue gas originated from burning of fossil fuels. MMMs of different compositions were prepared by doping glassy polymer Ultrason® S 6010 (US) with nanocrystals of zeolitic imidazolate frameworks (ZIF‐302) in varying degrees. A solution‐casting technique was used to fabricate various MMMs to optimize their CO2 capturing performance from both dry and wet gases. The prepared composite membranes indicated enhanced filler‐polymer interfacial adhesion, consistent distribution of nanofiller, and thermally stable matrix configuration. CO2 permeability of the membranes was enhanced as demonstrated by gas sorption and single gas permeation tests carried out under dry and moist circumstances. As compared to neat Ultrason® membrane, CO2 permeability and expected CO2/N2 permselectivity of the mixed membrane doped with 40 g/g ZIF‐302 nanocrystals were significantly enhanced. In contrast to the majority of previously reported membranes, key features of fabricated MMMs include their structural stability under humid conditions coupled with better and unaffected gas separation performance.
Application of Mono‐ and Disaccharides in Drug Targeting and Efficacy
Authors: Yuan Si S. , Li Mao L. , Chen Jian S. , Zhou Li , Zhou Wen 
Published: February 2018

AbstractCarbohydrates and their conjugates play important roles in many biological processes including fertilization, differentiation, development, immune response, and infection. Their activities are largely dependent on the properties of terminal mono‐ or disaccharides. Galactose, mannose, fucose, glucose, sialic acid, etc., are commonly used as powerful scaffolds installed on drug molecules for targeting specific tissues including brain, liver, and cancers, and as epitopes for enhancing the targeting of various vaccines. This review focuses on the influence of their structural variations, including changes in sugar type, substituent groups and their positions, as well as length of linker portion, on the targeting of drugs or their efficacy. Particular attention is paid to the targeting properties of mono‐ and disaccharides applied in drug design and discovery.
A survey on security issues in services communication of Microservices‐enabled fog applications
Authors: Yu Dongjin , Jin Yike , Zhang Yuqun , Zheng Xi 
Published: February 2018

SummaryFog computing is used as a popular extension of cloud computing for a variety of emerging applications. To incorporate various design choices and customized policies in fog computing paradigm, Microservices is proposed as a new software architecture, which is easy to modify and quick to deploy fog applications because of its significant features, ie, fine granularity and loose coupling. Unfortunately, the Microservices architecture is vulnerable due to its wildly distributed interfaces that are easily attacked. However, the industry has not been fully aware of its security issues. In this paper, a survey of different security risks that pose a threat to the Microservices‐based fog applications is presented. Because a fog application based on Microservices architecture consists of numerous services and communication among services is frequent, we focus on the security issues that arise in services communication of Microservices in four aspects: containers, data, permission, and network. Containers are often used as the deployment and operational environment for Microservices. Data is communicated among services and is vital for every enterprise. Permission is the guarantee of services security. Network security is the foundation for secure communication. Finally, we propose an ideal solution for security issues in services communication of Microservices‐based fog applications.
Optimizing Structural, Microhardness, Surface Growth Mechanism, Luminescence and Thermal Traits of KH2PO4 Crystal Exploiting Multidirectional H‐Bonding Quality of Dopant Tartaric Acid
Authors: Anis Mohd , Baig Mirza Irshad , Pandian Muthu Senthil , Ramasamy P. , AlFaify Salem , Ganesh Venga , Muley Gajanan G. , Ghramh Hamed Ali 
Published: February 2018

AbstractHigh‐end nonlinear optical devices demand superior quality KH2PO4 crystal and to meet this necessity slow solvent evaporation technique is employed to grow optical quality potassium dihydrogen orthophosphate (KH2PO4, KDOP) crystal by doping tartaric acid (TA) and special attention is devoted to optimize the defect influenced properties of KDOP crystal. The incorporation of TA in KDOP crystal matrix is evaluated by employing energy dispersive spectroscopic technique. The crystalline phase and structural dimensions of pure and TA doped KDOP crystal is evaluated by means of powder X‐ray diffraction analysis. The luminescence behavior of TA doped KDOP crystal is examined in visible region and violet colored emission is evidenced at 408 nm. The Vickers microhardness studies are carried out to uncover the constructive influence of TA on hardness and elastic stiffness coefficient of KDOP crystal. Impressive role of TA in minimizing defect density and improving the surface growth mechanism of KDOP crystal is explored by chemical etching analysis. The thermogravimetric analysis curve is traced within 30–650 °C and TA doped KDOP crystal is found thermally stale up to 233 °C. The results are appraised to propose the suitability of TA doped KDOP crystal for distinct applications.
Wet Imprinting of Channel‐Type Superstructures in Nanostructured Titania Thin Films at Low Temperatures for Hybrid Solar Cells
Authors: Song Lin , Wang Tianyi , Körstgens Volker , Wang Weijia , Saxena Nitin , Schaffer Christoph J. , Fröschl Thomas , Hüsing Nicola , Bernstorff Sigrid , Müller‐Buschbaum Peter 
Published: February 2018

AbstractHierarchically structured titania films, exhibiting interconnected foam‐like nanostructures and large‐scale channel‐type superstructures, were achieved in an energy‐saving way at low temperatures by a polymer template‐assisted sol–gel synthesis in combination with a wet‐imprinting process. The surface morphology was probed with scanning electron microscopy and atomic force microscopy, whereas the inner morphology was characterized with grazing incidence small‐angle X‐ray scattering measurements. Compared to the initial hybrid films, the titania films showed reduced structure sizes caused by removal of the polymer template. UV/Vis measurements showed an additional light‐scattering effect at various angles of light incidence in the hierarchically structured titania films, which resulted in higher light absorption in the wet‐imprinted active layer. To give proof of viability, the titania films were evaluated as photoanodes for dye‐free hybrid solar cells. The dye‐free layout allowed for low‐cost fabrication, avoided problems related to dye bleaching, and was a more environmentally friendly alternative to using dyes. Under different angles of light incidence, the enhancement in the short‐circuit current density was in good agreement with the improvement in light absorption in the superstructured active layer, demonstrating a positive impact of the superstructures on the photovoltaic performance of hybrid solar cells.
Chloroplastic and nuclear diversity of wild beets at a large geographical scale: Insights into the evolutionary history of the Beta section
Authors: Touzet Pascal , Villain Sarah , Buret Laetitia , Martin Hélène , Holl Anne‐Catherine , Poux Céline , Cuguen Joël 
Published: February 2018

AbstractHistorical demographic processes and mating systems are believed to be major factors in the shaping of the intraspecies genetic diversity of plants. Among Caryophyllales, the Beta section of the genus Beta, within the Amaranthaceae/Chenopodiaceae alliance, is an interesting study model with species and subspecies (Beta macrocarpa, Beta patula, Beta vulgaris maritima and B.v. adanensis) differing in geographical distribution and mating system. In addition, one of the species, B. macrocarpa, mainly diploid, varies in its level of ploidy with a tetraploid cytotype described in the Canary Islands and in Portugal. In this study, we analyzed the nucleotide diversity of chloroplastic and nuclear sequences on a representative sampling of species and subspecies of the Beta section (except B. patula). Our objectives were (1) to assess their genetic relationships through phylogenetic and multivariate analyses, (2) relate their genetic diversity to their mating system, and (3) reconsider the ploidy status and the origin of the Canarian Beta macrocarpa.
Adaptation to fluctuations in temperature by nine species of bacteria
Authors: Saarinen Kati , Laakso Jouni , Lindström Leena , Ketola Tarmo 
Published: February 2018

AbstractRapid environmental fluctuations are ubiquitous in the wild, yet majority of experimental studies mostly consider effects of slow fluctuations on organism. To test the evolutionary consequences of fast fluctuations, we conducted nine independent experimental evolution experiments with bacteria. Experimental conditions were same for all species, and we allowed them to evolve either in fluctuating temperature alternating rapidly between 20°C and 40°C or at constant 30°C temperature. After experimental evolution, we tested the performance of the clones in both rapid fluctuation and in constant environments (20°C, 30°C and 40°C). Results from experiments on these nine species were combined meta‐analytically. We found that overall the clones evolved in the fluctuating environment had evolved better efficiency in tolerating fluctuations (i.e., they had higher yield in fluctuating conditions) than the clones evolved in the constant environment. However, we did not find any evidence that fluctuation‐adapted clones would have evolved better tolerance to any measured constant environments (20°C, 30°C, and 40°C). Our results back up recent empirical findings reporting that it is hard to predict adaptations to fast fluctuations using tolerance curves.
Environmental consequences of deltamethrin residues in cattle feces in an African agricultural landscape
Authors: Sands Bryony , Mgidiswa Neludo , Nyamukondiwa Casper , Wall Richard 
Published: February 2018

AbstractPyrethroid insecticides are widely used to control ectoparasites of livestock, particularly ticks and biting flies. Their use in African livestock systems is increasing, driven by the need to increase productivity and local food security. However, insecticide residues present in the dung after treatment are toxic to dung‐inhabiting insects. In a semiarid agricultural habitat in Botswana, dung beetle adult mortality, brood ball production, and larval survival were compared between untreated cattle dung and cattle dung spiked with deltamethrin, to give concentrations of 0.01, 0.1, 0.5, or 1 ppm. Cattle dung‐baited pitfall traps were used to measure repellent effects of deltamethrin in dung on Scarabaeidae. Dung decomposition rate was also examined. There was significantly increased mortality of adult dung beetles colonizing pats that contained deltamethrin compared to insecticide‐free pats. Brood ball production was significantly reduced at concentrations of 1 ppm; larval survival was significantly reduced in dung containing 0.1 ppm deltamethrin and above. There was no difference in the number of Scarabaeidae attracted to dung containing any of the deltamethrin concentrations. Dung decomposition was significantly reduced even at the lowest concentration (0.01 ppm) compared to insecticide‐free dung. The widespread use of deltamethrin in African agricultural ecosystems is a significant cause for concern; sustained use is likely to damage dung beetle populations and their provision of environmentally and economically important ecosystem services. Contaminated dung buried by paracoprid (tunneling) beetles may retain insecticidal effects, with impacts on developing larvae below ground. Lethal and sublethal effects on entire dung beetle (Scarabaeidae) communities could impair ecosystem function in agricultural landscapes.
Chemical signaling and insect attraction is a conserved trait in yeasts
Authors: Becher Paul G. , Hagman Arne , Verschut Vasiliki , Chakraborty Amrita , Rozpędowska Elżbieta , Lebreton Sébastien , Bengtsson Marie , Flick Gerhard , Witzgall Peter , Piškur Jure 
Published: February 2018

AbstractYeast volatiles attract insects, which apparently is of mutual benefit, for both yeasts and insects. However, it is unknown whether biosynthesis of metabolites that attract insects is a basic and general trait, or if it is specific for yeasts that live in close association with insects. Our goal was to study chemical insect attractants produced by yeasts that span more than 250 million years of evolutionary history and vastly differ in their metabolism and lifestyle. We bioassayed attraction of the vinegar flyDrosophila melanogasterto odors of phylogenetically and ecologically distinct yeasts grown under controlled conditions. Baker's yeastSaccharomyces cerevisiae, the insect‐associated speciesCandida californica,Pichia kluyveriandMetschnikowia andauensis, wine yeastDekkera bruxellensis, milk yeastKluyveromyces lactis, the vertebrate pathogensCandida albicansandCandida glabrata, and oleophilicYarrowia lipolyticawere screened for fly attraction in a wind tunnel. Yeast headspace was chemically analyzed, and co‐occurrence of insect attractants in yeasts and flowering plants was investigated through a database search. In yeasts with known genomes, we investigated the occurrence of genes involved in the synthesis of key aroma compounds. Flies were attracted to all nine yeasts studied. The behavioral response to baker's yeast was independent of its growth stage. In addition toDrosophila, we tested the basal hexapodFolsomia candida(Collembola) in a Y‐tube assay to the most ancient yeast,Y. lipolytica,which proved that early yeast signals also function on clades older than neopteran insects. Behavioral and chemical data and a search for selected genes of volatile metabolites underline that biosynthesis of chemical signals is found throughout the yeast clade and has been conserved during the evolution of yeast lifestyles. Literature and database reviews corroborate that yeast signals mediate mutualistic interactions between insects and yeasts. Moreover, volatiles emitted by yeasts are commonly found also in flowers and attract many insect species. The collective evidence suggests that the release of volatile signals by yeasts is a widespread and phylogenetically ancient trait, and that insect–yeast communication evolved prior to the emergence of flowering plants. Co‐occurrence of the same attractant signals in yeast and flowers suggests that yeast‐insect communication may have contributed to the evolution of insect‐mediated pollination in flowers.