167 research outputs found

    Precision bond lengths for Rydberg Matter clusters KN (N = 19, 37, 61 and 91) in excitation levels n = 4 - 8 from rotational radio-frequency emission spectra

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    Clusters of the electronically excited condensed matter Rydberg Matter (RM) are planar and six-fold symmetric with magic numbers N = 7, 19, 37, 61 and 91. The bond distances in the clusters are known with a precision of +- 5% both from theory and Coulomb explosion experiments. Long series of up to 40 consecutive lines from rotational transitions in such clusters are now observed in emission in the radio-frequency range 7-90 MHz. The clusters are produced in five different vacuum chambers equipped with RM emitters. The most prominent series with B = 0.9292 +- 0.0001 MHz agrees accurately with expectation (within 2%) for the planar six-fold symmetric cluster K19 in excitation level n = 4. Other long series agree even better with K19 at n = 5 and 6. The ratio between the interatomic distance and the theoretical electron orbit radius (the dimensional ratio) for K19 in n = 4 is found to be 2.8470 +- 0.0003. For clusters K19 (n = 6) and K37 (n = 7 and 8) the dimensional ratio 2.90 is the highest value that is found, which happens to be exactly the theoretical value. Clusters K61 and K91 in n = 5 and 6 have slightly lower dimensional ratios. This is expected since the edge effects are smaller. Intensity alternations are observed of approximately 7:3. The nuclear spins interact strongly with the magnetic field from the orbiting electrons. Spin transitions are observed with energy differences corresponding accurately (within 0.6%) to transitions with apparent total (delta)F = -3 at excitation levels n = 5 and 6. The angular momentum coupling schemes in the clusters are complex but well understood.Comment: 37 pages, 14 figure

    Synthesis of 1,2-Disubstituted Benzimidazoles in the Presence of SBA-Pr-SO 3 H as a Nano Solid Acid Catalyst

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    Abstract In this article, simple, convenient synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazole (1,2-disubstituted benzimidazoles) via condensation of 1,2-phenylenediamine and aromatic aldehydes using SBA-Pr-SO 3 H as a nanoporous solid acid catalyst in green protocol was reported. JNS All rights reserve

    Zinc deficiency as a codeterminant for airway epithelial barrier dysfunction in an ex vivo model of COPD

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    There is now convincing evidence that the airway epithelium drives the pathogenesis of COPD. A major aspect of this is the disease-related reduction in barrier function that is potentiated by dysregulation of tight junction (TJ) protein complexes. However, a significant number of studies using in vitro smoke exposure models have not observed alterations in barrier permeability. We have previously shown that zinc (Zn) is an influential cytoprotective factor for the airway epithelium, and its depletion by cigarette smoke produces disease-related modifications consistent with inflammatory changes in COPD. We hypothesized that Zn deficiency is a significant co-stimulus with cigarette smoke extract (CSE) for potentiating the leaky barrier phenotype exhibited in COPD. We employed an ex vivo model of differentiated human airway epithelium exposed to Zn depletion and CSE to determine the contribution of Zn in maintaining normal epithelial permeability. Western blot analysis demonstrated a significant downregulation of the TJ proteins such as ZO-1 (-1.93-fold, P<0.05) and Claudin-1 (-3.37-fold, P<0.01) with the combination exposure. Assessment of barrier function via paracellular ionic conductance and tracer permeability also showed that Zn depletion was an important factor, which potentiated an increase in epithelial permeability (P<0.001 for both) compared to Zn depletion or CSE exposures in isolation. Visual inspection of the epithelium using transmission electron microscopy revealed a marked reduction in junction complexes between the adjacent airway epithelial cells treated with a combination of Zn depletion and CSE. These observations identify Zn deficiency as a significant codeterminant with CSE as a factor leading to an increase in airway epithelial permeability. Hence, as Zn dyshomeostasis has been reported in the airway epithelium exposed to chronic cigarette smoke and inflammation, targeting these phenomena may represent a promising strategy to ameliorate the leaky barrier phenotype that is synonymous with COPD.Eugene Roscioli, Hubertus PA Jersmann, Susan Lester, Arash Badiei, Andrew Fon, Peter Zalewski, Sandra Hodg

    The phases of deuterium at extreme densities

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    We consider deuterium compressed to higher than atomic, but lower than nuclear densities. At such densities deuterium is a superconducting quantum liquid. Generically, two superconducting phases compete, a "ferromagnetic" and a "nematic" one. We provide a power counting argument suggesting that the dominant interactions in the deuteron liquid are perturbative (but screened) Coulomb interactions. At very high densities the ground state is determined by very small nuclear interaction effects that probably favor the ferromagnetic phase. At lower densities the symmetry of the theory is effectively enhanced to SU(3), and the quantum liquid enters a novel phase, neither ferromagnetic nor nematic. Our results can serve as a starting point for investigations of the phase dynamics of deuteron liquids, as well as exploration of the stability and dynamics of the rich variety of topological objects that may occur in phases of the deuteron quantum liquid, which range from Alice strings to spin skyrmions to Z_2 vortices.Comment: 9 pages, 6 figures; v2: fixed typo

    Updated Systematic Review and Meta-Analysis of the Performance of Risk Prediction Rules in Children and Young People with Febrile Neutropenia

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    Introduction: Febrile neutropenia is a common and potentially life-threatening complication of treatment for childhood cancer, which has increasingly been subject to targeted treatment based on clinical risk stratification. Our previous meta-analysis demonstrated 16 rules had been described and 2 of them subject to validation in more than one study. We aimed to advance our knowledge of evidence on the discriminatory ability and predictive accuracy of such risk stratification clinical decision rules (CDR) for children and young people with cancer by updating our systematic review. Methods: The review was conducted in accordance with Centre for Reviews and Dissemination methods, searching multiple electronic databases, using two independent reviewers, formal critical appraisal with QUADAS and meta-analysis with random effects models where appropriate. It was registered with PROSPERO: CRD42011001685. Results: We found 9 new publications describing a further 7 new CDR, and validations of 7 rules. Six CDR have now been subject to testing across more than two data sets. Most validations demonstrated the rule to be less efficient than when initially proposed; geographical differences appeared to be one explanation for this. Conclusion: The use of clinical decision rules will require local validation before widespread use. Considerable uncertainty remains over the most effective rule to use in each population, and an ongoing individual-patient-data meta-analysis should develop and test a more reliable CDR to improve stratification and optimise therapy. Despite current challenges, we believe it will be possible to define an internationally effective CDR to harmonise the treatment of children with febrile neutropenia

    H2S biosynthesis and catabolism: new insights from molecular studies

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    Hydrogen sulfide (H2S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H2S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H2S within tissues. Studies utilising these systems are revealing new insights into the biology of H2S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H2S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H2S gas within tissue
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