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  • Wiley-Blackwell  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Polymerization by phase transfer catalysis, 2Part 1: cf.18. Polythiocarbonates by polymerization of Bisphenol A with thiophosgene (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 915-921 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(oxythiocarbonyloxy-1,4-phenyleneisopropylidene-1,4-phenylene) (1) was obtained from 4,4′-isopropylidenediphenol (Bisphenol A) and thiophosgene under phase transfer conditions, using quaternary ammonium and phosphonium salts and crown ethers as catalysts. The polymer was identified by IR and 1H NMR spectroscopy, and the molecular weights were estimated from inherent viscosity measurements. The influence of catalysts, solvent and thiophosgene addition was studied in order to find the best conditions. It was found that tetrabutylammonium bromide, dichloromethane and the addition of thiophosgene at once gives the highest yields and inherent viscosities. Other catalysts and solvents were less efficient or unefficient for this reaction.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860503
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of poly(2-selenolylmethyl methacrylate) (1986)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 7 (1986), S. 553-555 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1986.030070903
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  • 3
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    Stratification and residence time as factors controlling the seasonal variation and the vertical distribution of chlorophyll-a in a subtropical irrigation reservoir (2016)
    Wiley-Blackwell
    Details
    Publication Date: 2016-03-03
    Description: Reservoir trophic state is controlled by light and nutrient availability, as well as by hydraulic management and stratification pattern. In arid zone reservoirs, the inflow and outflow discharges have extreme seasonal variations which produce well-defined cycles of filling and draining. Moreover, since stratification often occurs, epilimnion and hypolimnion renewal rates may vary producing different environmental conditions throughout the water column. These variation patterns may affect phytoplankton growth at both temporal and spatial scales. For two hydrological years, we analyzed the influence of light climate, nutrients, residence time (Tw), and stratification on phytoplankton biomass (as chlorophyll- a [Chl- a ]) in an irrigation reservoir (276 hm 3 ) in the arid central Andes in Argentina (33°S). The reservoir was turbid ( Z Secchi : 1.4 m) with relatively high levels of dissolved nitrogen and phosphorus (60 μgP L −1 and 560 μgN L −1 , respectively). Stratification occurred from mid-spring to late-summer, when hypolimnetic oxygen and pH decreased whereas dissolved nutrients increased. The reservoir was mesotrophic (Chl- a : 4.6–10.8 μg L −1 ) and showed two semi-annual peaks of Chl- a (summer and winter). Depending on the water column circulation, Chl- a was directly related to Tw for 60 〉 Tw 〉 200 and inversely to ammonia, during mixing and stratification periods, respectively. Phytoplankton development was strongly influenced by the seasonal variations of inflow/outflow and stratification. Chl- a peaked in summer, when inflow plunged into the hypolimnion of the stratified reservoir and in the warm and mixed epilimnion algae proliferated until nutrients depletion. Alternatively, the winter Chl- a maximum is likely to be produced by the higher concentration of nutrients combined with the turbulent mixing in the water column which acts as a mechanism that helps to overcome light-limitation. Since stratification modifies the vertical distribution of Tw, the use of a single annual value of this hydraulic parameter to assess its effect on the reservoir trophic state results inadequate. This paper constitutes the first description of hydrologic effects on Chl- a dynamics in a reservoir in arid central western Argentina.
    Print ISSN: 1434-2944
    Electronic ISSN: 1522-2632
    Topics: Biology
    Published by Wiley-Blackwell
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  • 4
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    Periodically structured X-ray waveguides (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2013-07-24
    Description: The properties of X-ray vacuum-gap waveguides (WGs) with additional periodic structure on one of the reflecting walls are studied. Theoretical considerations, numerical simulations and experimental results confirm that the periodic structure imposes additional conditions on efficient propagation of the electromagnetic field along the WGs. The transmission is maximum for guided modes that possess sufficient phase synchronism with the periodic structure (here called `super-resonances'). The field inside the WGs is essentially given at low incidence angle by the fundamental mode strongly coupled with the corresponding phased-matched mode. Both the simulated and the experimental diffraction patterns show in the far field that propagation takes place essentially only for low incidence angles, confirming the mode filtering properties of the structured X-ray waveguides.
    Print ISSN: 0909-0495
    Electronic ISSN: 1600-5775
    Topics: Geosciences , Physics
    Published by Wiley-Blackwell on behalf of International Union of Crystallography (IUCr).
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  • 5
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    Increased breast cancer screening and down-staging in Colombian women: A randomized trial of opportunistic breast-screening (2015)
    Wiley-Blackwell
    Details
    Publication Date: 2015-08-13
    Description: ABSTRACT The lack of breast cancer screening in low and middle-income countries results in later stage diagnosis and worsened outcomes for women. A cluster randomized trial was performed in Bogotá, Colombia between 2008-2012 to evaluate effects of opportunistic breast cancer screening. Thirteen clinics were randomized to an intervention arm and 13 to a control arm. Physicians in intervention clinics were instructed to perform clinical breast examination on all women aged 50-69 years attending clinics for non-breast health issues, and then refer them for mammographic screening. Physicians in control clinics were not explicitly instructed to perform breast screening or mammography referrals, but could do so if they thought it indicated (‘usual care'). Women were followed for 2-years post-randomization. 7436 women were enrolled and 7419 (99.8%) screened in intervention clinics, vs. 8419 enrolled and 1,108 (13.1%) screened in control clinics. Incidence ratios (IR) of early, advanced and all breast cancers were 2.9 (95% CI 1.1-9.2), 1.0 (0.3-3.5) and 1.9 (0.9-4.1) in the first (screening) year of the trial, and the cumulative IR for all breast cancers converged to 1.4 (0.7-2.8) by the end of follow-up (year 2). Eighteen (69.2%) of 26 women with early stage disease had breast conservation surgery (BCS) vs. 6 (42.5%) of 14 women with late-stage disease (p=0.02). Fifteen (68.2%) of 22 women with breast cancer in the intervention group had BCS vs. 9 (50.0%) of 18 women in the control group (p=0.34). Well-designed opportunistic clinic-based breast cancer screening programs may be useful for early breast cancer detection in LMICs. This article is protected by copyright. All rights reserved. © 2014 Wiley Periodicals, Inc.
    Print ISSN: 0020-7136
    Electronic ISSN: 1097-0215
    Topics: Biology , Medicine
    Published by Wiley-Blackwell
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