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  • 1
    Electronic Resource
    Electronic Resource
    The site of radical attack at the furan ring from MNDO calculations (1992)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 1 (1992), S. 99-103 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The semi-empirical SCF MNDO method has been used to calculate the radical reactivities for each reaction site in some neutral furan molecules as the average of the HOMO and LUMO probabilities both in 2pz atomic orbitals1SCF: Self-consistent field; MNDO: modified neglect of differential overlap; HOMO: highest occupied molecular orbital; LUMO: lowest unoccupied molecular orbital.. The carbon atoms C5 and C2 of of the furan ring are the most favoured sites except for the furan derivatives holding a double bond in the substituent group. Also the SOMO2SOMO: Single occupied molecular orbital. probabilities of the radicals formed by addition of a hydrogen atom or a vinyl acetate model radical were calculated. Thus, once a radical is added to the C5 position the resulting radical can be partially localized on the carbon C2. Furthermore, the enthalpy of reaction for several radicals was estimated by using the calculated heats of formation of the neutral furan molecules and their radicals. The radical addition to the carbon C 5 resulted in the most exothermic reaction in comparison with other reaction sites of the molecule. However, no correlation was found between the calculated enthalpies and the degradative-transfer kinetic constants experimentally determined for the radical polymerization of vinyl acetate in the presence of the furan compounds under study.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1992.040010205
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical approach to cationic polymerization of alkenylfuranes (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 281-287 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular species proposed for the initial steps in the cationic polymerization of alkenylfurans were modeled by MNDO theoretically fully optimized structures. It was confirmed that the anomalous reactivity of ring C-5 of the monomers is determined by HOMO electron densitites, whereas calculated proton affinities from the semiempirical heats of formation fail to explain the low temperature experimental behavior of 2-vinylfuran (1c) from the point of view of stability of intermediate species. However, ab initio 4-31G calculations of proton affinities agree with the experimental facts and allow further explanations of the reactivity of furan derivatives in electrophilic media.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910202
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of the initiator absorbance on the transition-metal complex photoinitiated polymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 207-208 
    Details
    ISSN: 0887-624X
    Keywords: photoinitiated polymerization ; initiator absorbance ; metal complex ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Calorimetric determination of the heat capacity changes associated with the conformational transitions of polyriboadenylic acid and polyribouridylic acid (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2641-2652 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat capacities of the single-stranded and double-stranded forms of polyadenylic acid, polyuridylic acid, and poly(uridylic and adenylic acid) were determined with a drop heat capacity calorimeter. In addition, the temperature dependence of the apparent partial heat capacity (φCp) was measured with a newly developed differential scanning calorimeter. The calculated ΔCp at 28°C for the transition poly(A)·poly(A) ⇄ 2 poly(A) was found to be 165 ± 24 cal/Kmol-base pair, compared with a value of 140 ± 28 for the transition poly(A)·poly(U) ⇄ poly(A) + poly(U). The temperature dependence of φCp of single-stranded poly(U) was consistent with the conclusion that it is totally unstacked at temperatures above 15°C. The temperature dependence of φCp of single-stranded poly(A) was used to determine the base-stacking parameters for poly(A). The experimental results are consistent with a stacking enthalpy change of -8.5 ± 0.1 kcal/mol bases and a cooperativity parameter σ of 0.57 ± 0.03 for the stacking of adenine bases. These results demonstrate that the heat capacity of single-stranded polynucleotides is greater than that of the double-stranded forms. This increased heat capacity is mainly the result of the temperature dependence of the base-stacking interactions in the single-stranded form.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360161206
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  • 5
    Electronic Resource
    Electronic Resource
    Raman spectroscopic study of ion association in aqueous magnesium sulphate solutions (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 933-941 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A Raman spectroscopic study of aqueous solutions of MgSO4 as function of concentration and temperature was performed. From the analysis of the band profile of the internal vibrations of the sulphate ion, the spectroscopic ionic association constant was calculated at different temperatures. It was found that the association is solvent separated in the ranges of concentration and temperature studied. The large differences observed between the values obtained for the spectroscopic association constant and those obtained from macroscopic measurements were interpreted on the basis of a four-step solvent-separated dehydration mechanism. It is, assumed that the Raman spectra reflect only the short-distance force acting on the sulphate anions. The contribution of the long-range forces for the consecutive steps were calculated using the Bjerrum equation. Good agreement between the overall association constant thus calculated and the macroscopic value was found in the concentration and temperature ranges studied.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250251206
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  • 6
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    Intercomparison of standard resolution and high resolution TOVS soundings with radiosonde, lidar, and surface temperature/humidity data (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: One objective of the FIRE Cirrus IFO is to characterize relationships between cloud properties inferred from satellite observations at various scales to those obtained directly or inferred from very high resolution measurements. Satellite derived NOAA-9 high and standard resolution Tiros Operational Vertical Sounder (TOVS) soundings are compared with directly measured lidar, surface temperature, humidity, and vertical radiosonde profiles associated with the Ft. McCoy site. The results of this intercomparison should be useful in planning future cloud experiments.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: FIRE Science Results 1989; p 491-495
    Format: application/pdf
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  • 7
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    A numerical technique for the calculation of cloud optical extinction from lidar (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A simple numerical algorithm which calculates optical extinction from cloud lidar data is presented. The method assumes a two-component atmosphere consisting of 'clear air' and cloud particulates. 'Clear air' may consist of either molecules only or a mix of molecules and atmospheric aerosols. For certain clouds, the method may be utilized to provide an estimate of the cloud-atmospheric parameter defined as the ratio of the cloud volume backscatter coefficient to the cloud extinction coefficient divided by the atmospheric volume backscatter coefficient at a given altitude. The cloud-atmospheric parameter may be estimated only from cloud data from which the optical thickness may reliably be used as a constraint on the numerical solution. This constraint provides the additional information necessary to obtain the cloud-atmospheric parameter. Conversely, the method may be applied to obtain cloud extinction and optical thickness from lidar cloud soundings if an estimate of the cloud-atmospheric parameter is available.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: The FIRE Cirrus Science Results 1993; p 67-70
    Format: application/pdf
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  • 8
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    CSU FIRE 2 cirrus field experiment: Description of field deployment phase (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Colorado State University (CSU) surface observing systems are described. These systems were deployed at the Parsons, Kansas site during the FIRE 2 Cirrus Special Observing Period (SOP) from 13 Nov. - 7 Dec. 1991. The geographical coordinates of the site containing most of the CSU instrumentation are 37 deg. 18 min N. latitude and 96 deg. 30 min. W. longitude; site elevation was 269 meters. In addition, one surface meteorological and broadband flux observing site was maintained at the Tri City Airport which is approximately 18 miles due west of Parsons (37 deg. 20 min. N. latitude, 95 deg. 30 min. 30 sec. W. longitude). A map of the locations of the CSU deployment sites is presented. At the main Parsons site, the instrumentation was located directly adjacent to and north of a lake. Under most cirrus observing conditions, when the wing had a significant southernly component, the lake was upwind of the observing site. The measurements and observations collected during the experiment are listed. These measurements may be grouped into five categories: surface meteorology; infrared spectral and broadband measurements; solar spectral and broadband measurements; upper air measurements; and cloud measurements. A summary of observations collected at the Parsons site during the SOP are presented. The wind profiler, laser ceilometer, surface meteorology and surface broadband radiation instrumentation were operated on a continuous basis. All other systems were operated on an 'on demand' basis when cloud conditions merited the collection of data.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA-CR-193162 , NAS 1.26:193162 , FIRE-SER-8 , ATMOSPHERIC-SCI-PAPER-506
    Format: application/pdf
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