34 research outputs found

    Quantum phases of hard-core dipolar bosons in coupled one-dimensional optical lattices

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    Hard-core dipolar bosons trapped in a parallel stack of N ≥ 2 one-dimensional optical lattices (tubes) can develop several phases made of composites of particles from different tubes: superfluids, supercounterfluids, and insulators as well as mixtures of those. Bosonization analysis shows that these phases are thresholdless with respect to the dipolar interaction, with the key “control knob” being filling factors in each tube, provided the intertube tunneling is suppressed. The effective ab initio quantum Monte Carlo algorithm capturing these phases is introduced and some results are presented.National Science Foundation (U.S.) (Grant CNS-0855217)National Science Foundation (U.S.) (Grant CNS-0958379)National Science Foundation (U.S.) (Grant ACI-1126113

    Synthesis, Structural Characterization and Catalytic Activity of Indenyl Complexes of Ruthenium Bearing Fluorinated Phosphine Ligands

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    The synthesis, characterization and catalytic activity of new ruthenium complexes of fluorinated triarylphosphines is described. The new ruthenium complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] were synthesized in 57% and 24% isolated yield, respectively, by thermal ligand exchange of [RuCl(ind)(PPh3)2], where ind = indenyl ligand η5-C9H7−. The electronic and steric properties of the new complexes were studied through analysis of the X-ray structures and through cyclic voltammetry. The new complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] and the known complex [RuCl(ind)(PPh3)2}] differed only slightly in their steric properties, as seen from comparison of bond lengths and angles associated with the ruthenium center. As determined by cyclic voltammetry, the redox potentials of [RuCl(ind)(PPh3){P(p-C6H4CF3)3}] and [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] are +0.173 and + 0.370 V vs. Cp2Fe0/+, respectively, which are substantially higher than that of [RuCl(ind)(PPh3)2] (−0.023 V). After activation through chloride abstraction, the new complexes are catalytically active in the etherification of propargylic alcohols (8–24 h at 90 °C in toluene, 1–2 mol% catalyst loading, 29–61% isolated yields). As demonstrated by a comparative study for a test reaction, the three precursor complexes [RuCl(ind)(PPh3){P(p-C6H4CF3)3}], [RuCl(ind)(PPh3){P(3,5-C6H3(CF3)2)3}] and [RuCl(ind)(PPh3)2}] differed only slightly in catalytic activity

    Electrochemical investigation of the kinetics of chloride substitution upon reduction of [Ru(porphyrin)(NO)Cl] complexes in THF.

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    The electrochemistry of several ruthenium porphyrin nitrosyl chloride complexes [Ru(por)(NO)Cl] have been examined in tetrahydrofuran. The complexes undergo 1-electron irreversible reductions which result in the diffusion-limited substitutions of the chloride ligands for THF. This chloride metathesis is reversible in the presence of added NBu4Cl, and equilibrium constants and rate constants for chloride loss have been estimated. These parameters correlate with the NO stretching frequencies of the parent complexes, with more electron-donating porphyrin ligands favouring chloride loss from the reduced complexes. The [Ru(por)(NO)(THF)] products of the reductions can be detected by IR, EPR and visible spectroscopies. These species undergo three further reductions, with good reversibility at scan rates \u3e0.40 V s-1. The [Ru(por)(NO)(THF)]+/0 couples have also been determined, and the rate constants and equilibrium constants for recombination with chloride have been estimated. One-electron reductions of the [Ru(por)(NO)Cl] complexes result in ~1018 enhancement of the rates of chloride loss

    Are water-centric themes in sustainable tourism research congruent with the UN Sustainable Development Goals?

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    Although tourism is considered a vehicle for achieving the UN Sustainable Development Goals (SDGs) to eradicate poverty, protect the environment and facilitate social inclusion, limited empirical work has assessed the engagement of tourism literature with the associated 2030 Agenda. Water, both fresh and salt, is directly or indirectly implicated throughout the SDGs, and tourism both depends on clean water and exacerbates water problems. However, there has been limited discourse that maps water-centric knowledge and its relationship to the SDGs within the sustainable tourism literature. This bibliometric analysis, consequently, draws on a database of 220 relevant journal articles to identify affiliated themes and assess their relationship to the SDGs. Findings categorise the knowledge base into three first order themes, with water situated respectively as resource, attraction and hazard. This literature indirectly supports the Agenda through specific SDGs of poverty eradication (#1), sustainable economic growth (#8), and sustainable consumption (#12). Direct links occur between the themes and specific SDGs, as with resource (#6, sustainable management of water for all), attraction (#14, life beneath the sea) and hazard (#13, climate change action). Future research in the tourism and water nexus should consider deeper engagement with priorities as outlined in the SDGs.</p

    Dysregulation of Key Proteinases in Aspergillus fumigatus Induced by Blood Platelets

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    Background: Aspergillus fumigatus is the most common species causing invasive aspergillosis (IA), a life- threatening infection with more than 80 mortality. Interactions between A. fumigatus and human blood platelets lead to intravascular thrombosis and localized infarcts. To better understand A. fumigatus pathogenesis, we aimed to analyze the genetic basis of interactions between the pathogen and blood platelets.Methods: A bioinformatic pipeline on microarray gene expression dataset, including analysis of differentially expressed genes (DEGs) using Limma R package and their molecular function, as well as biological pathways identification, was conducted to find the effective genes involved in IA. In the wet phase, the gene expression patterns following fungal exposure to blood platelets at 15, 30, 60, and 180 min were evaluated by quantitative reverse transcriptase-PCR analysis.Results: Three genes encoding aspartic endopeptidases including (Pep1), (Asp f 13), and (P-glucanase) were the standing candidates. The invasion-promoting fungal proteinase-encoding genes were down- regulated after 30 min of hyphal incubation with blood platelets, and then up-regulated at 60 and 180 min, although only Pep1 was greater than the control at the 60and 180 min time points. Also, the same genes were downregulated in more the clinical isolates relative to the standard strain CBS 144.89.Conclusions: Our findings delineate the possible induction of fungal-encoded proteinases by blood platelets. This provides a new research line into A. fumigatus � molecular pathogenesis. Such insight into IA pathogenesis might also guide researchers toward novel platelet-based therapies that involve molecular interventions, especially in IA patients. © 2021, Reports of Biochemistry & Molecular Biology .All Rights Reserved

    Recent findings on the role of fungal products in the treatment of cancer

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    In modern medicine, natural products have aided humans against their battles with cancer. Among these products, microorganisms, medicinal herbs and marine organisms are considered to be of great benefit. In recent decades, more than 30 fungal immunity proteins have been identified and proved to be extractable from a wide range of fungi, including mushrooms. Although chemotherapy is used to overcome cancer cells, the side effects of this method are of great concern in clinical practice. Fungal products and their derivatives constitute more than 50 of the clinical drugs currently being used globally. Approximately 60 of the clinically approved drugs for cancer treatment have natural roots. Anti-tumor immunotherapy is prospective with a rapidly growing market worldwide due to its high efficiency, immunity, and profit. Polysaccharide extracts from natural sources are being used in clinical and therapeutic trials on cancer patients. This review aims to present the latest findings in cancer treatment through isolated and extraction of fungal derivatives and other natural biomaterials. © 2020, Federación de Sociedades Españolas de Oncología (FESEO)
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