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  • 1
    ISSN: 1572-879X
    Keywords: Nuclear magnetic resonance for catalyst characterization ; KF2Mn(CO)12 as catalyst precursor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Variable temperature13C MAS NMR spectra are reported for13CO-enriched KFe2Mn(CO)12 as a solid and also as dispersed clusters on a carbon support. The spectrum of KFe2Mn(CO)12 at 300 K agrees with the proposed structure for this cluster and shows that the cluster is static. Two bridging carbonyl resonances are clearly resolved and, by comparison with13C MAS NMR spectra of Mn2(CO)10 and Fe2(CO)9, all terminal resonances for the cluster can be assigned. When the cluster is supported on carbon, two broad resonances are observed at room temperature which are assignable to KFe2Mn(CO)12 and a decomposition product, Mn2(CO)10. The carbonyl ligands in both supported clusters are completely averaged, and KFe2Mn(CO)12 on the carbon surface demonstrates fluxional behavior similar to that observed for the cluster in solution. For this fluxional process, activation energies of 0.6 kcal/mol and 0.5 kcal/mol are estimated for carbon-supported KFe2Mn(CO)12 and Mn2(CO)10, respectively.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 8 (1991), S. 359-366 
    ISSN: 1572-879X
    Keywords: Potassium promotion ; iron based catalysts ; ammonia synthesis ; high pressure — ultra high vacuum (UHV) investigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ammonia synthesis rate has been measured as a function of the potassium coverage of a polycrystalline iron foil. The results clearly demonstrate a promoting effect of the potassium in agreement with the work of Ertl et al. on the dissociative dinitrogen adsorption at iron single crystal surfaces. However, the results also imply a marked difference between the state of the surface under ammonia synthesis conditions and during the dinitrogen adsorption experiments in ultra-high vacuum. It is suggested that in the former case the potassium atoms are surrounded by several strongly adsorbed atoms effectively blocking the corresponding sites for dinitrogen dissociation.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2018-01-17
    Description: BACKGROUND Herein, the authors evaluated how the time to testosterone rebound (TTR) after radiotherapy (RT) and 6 months of androgen deprivation therapy (ADT) impacted the risk of prostate cancer-specific mortality (PCSM) and cardiovascular-specific mortality (CVM) among men with varying comorbidity extent. METHODS Between 1995 and 2001, a total of 206 men who were randomized to receive RT either alone or with 6 months of ADT for unfavorable-risk PC and who had a comorbidity score assigned using the Adult Comorbidity Evaluation 27 metric comprised the study cohort. Multivariable competing risk regression was used to evaluate the impact of and possible interaction between comorbidity and TTR on PCSM and CVM. RESULTS After a median follow-up of 18.19 years, 30 men (18.6%), 39 men (24.2%), and 92 men (57.1%), respectively, had died of PC, CV disease, or other causes. As TTR increased, PCSM significantly decreased in men with no or minimal (adjusted hazard ratio [AHR], 0.53, 95% confidence interval [95% CI], 0.34-0.84 [ P =.007]) and moderate to severe (AHR, 0.37; 95% CI, 0.14-0.99 [ P = .048]) comorbidity. However, increasing TTR significantly increased the risk of CVM among men with moderate to severe comorbidity (AHR, 1.87; 95% CI, 1.40-2.49 [ P  〈.001]), but not those with no or minimal comorbidity (AHR, 0.86; 95% CI, 0.57-1.29 [ P =.46]), leading to a significant interaction between TTR and comorbidity ( P = .001). CONCLUSIONS The results of the current study indicate that considering an intermittent course of ADT such that the TTR approaches 18 months, instead of continuous long-term administration of ADT, in men with moderate to severe comorbidity and high-risk PC may reduce the increased risk of CVM without increasing the risk of PCSM. Cancer 2018 . © 2018 American Cancer Society .
    Print ISSN: 0008-543X
    Electronic ISSN: 1097-0142
    Topics: Biology , Medicine
    Published by Wiley-Blackwell on behalf of The American Cancer Society.
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  • 4
    Publication Date: 2018-02-17
    Description: The purpose of this study was to determine whether limited occurrence data for highly threatened species can provide useful spatial information to inform conservation. The study was conducted across central and southern China. We developed a habitat suitability model for the Critically Endangered Chinese giant salamander ( Andrias davidianus ) based on one biotic and three abiotic parameters from single-site locality records, which represent the only relevant environmental data available for this species. We then validated model quality by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. We randomly selected 48 counties containing historical records which were distinct from, and independent of, the single-site records used to develop the model, and 47 additional counties containing 〉50% predicted suitable habitat. We interviewed 2,812 respondents near potential giant salamander habitat across these counties and tested for differences in respondent giant salamander reports between counties selected using each method. Our model predicts that suitable giant salamander habitat is found widely across central and southern China, with counties containing ≥50% predicted suitable habitat distributed in 13 provinces. Counties with historical records contain significantly more predicted suitable habitat than counties without historical records. There are no statistical differences in any patterns of respondent giant salamander reports in surveyed counties selected from our model compared with the areas of known historical giant salamander distribution. A Chinese giant salamander habitat suitability model with strong predictive power can be derived from the restricted range of environmental variables associated with limited available presence-only occurrence records, constituting a cost-effective strategy to guide spatial allocation of conservation planning. Few reported sightings were recent, however, with most being over 20 years old, so that identification of areas of suitable habitat does not necessarily indicate continued survival of the species at these locations. To determine whether limited occurrence data can provide useful spatial information to inform conservation, we used one biotic and three abiotic parameters from single-site locality records to develop a habitat suitability model for the Critically Endangered Chinese giant salamander ( Andrias davidianus ). We then validated our model by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. The accuracy of our habitat suitability model was supported by a close statistical congruence with the pattern and timing of giant salamander reports made by local respondents across surveyed counties with known historical records of the species, showing that a restricted range of environmental correlates derived from a limited sample of presence-only occurrence records can, at least in some cases, be used to develop robust models with strong predictive power.
    Electronic ISSN: 2045-7758
    Topics: Biology
    Published by Wiley-Blackwell
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  • 5
    Publication Date: 2013-12-19
    Description: In this paper, we present the first experimental demonstration of double- and triple-band negative refraction index meta-foils in the terahertz (THz) region. Multi-band meta-foils constructed by multi-cell S-string resonators in a single structure exhibit simultaneously negative permittivity and negative permeability responses at multiple frequencies. The phenomena are confirmed by numerical simulations and Fourier transform infrared spectroscopy measurements. The flexible, freestanding multi-band meta-foils provide a promising candidate for the development of multi-frequency THz materials and devices. Scientific Reports 3 doi: 10.1038/srep03531
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
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