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  • 1
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding curves of various aminoacridines on calf thymus DNA have been determined by a spectrophotometric method. The dominant role of electrostatic forces in the interaction has been confirmed by the effect of ionic strength. Side chain and ring substituents in the aminoacridines do not inhibit binding, since this decreases in the order: acranil 〉 neomonacrin 〉 atebrin 〉 9-aminoacridine ∼ proflavine 〉 9-amino-1,2,3,4-tetrahydroacridine (THA). The last named shows the effect of diminishing the flat area of the rings in the aminoacridines. The shape of the binding curves of proflavine, 9-aminoacridine, and THA on thermally denatured DNA show that about 30-50% more binding sites are available to these cations on denatured DNA than on native DNA, but that the binding constants are the same. These observations are discussed in relation to the intercalation and other models for the interaction. It is concluded that exact and complete intercalation is not a necessary condition of strong binding and that other, less regular, models, in which the positive ring nitrogens of the acridines are close to the DNA phosphates and the acridine rings partially interact with the DNA base rings, are probably more consistent with the effect of denaturation of DNA on the binding curves which are characteristic of the interaction in solution.
    Additional Material: 7 Ill.
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intrinsic, viscosities at zero shear rate of defined complexes of proflavine, 9-aminoacridine, and 9-amino-l,2,3,4-tetrahydroaeridine with calf thymus DNA have been determined at, various ionic strengths by means of rotating cylinder viscometers. By controlled adjustment, of the composition of the mixtures, the amount of bound acridine (r moles/g.-atom DNA phosphorus) was maintained constant at different dilutions. The intrinsic viscosities of the complexes increased with r up to r values (ca. 0.16-0.20) corresponding to the end of the process of strong binding of the acridinium cations. However, complex formation between the acridines and thermally denatured DNA caused either a marked decrease in viscosity (at the low ionic strengths of 0.0015 and 0.005) or no change at all (ionic strength 0.1). These results are discussed in the light of presently available hydrodynamic theories relating the intrinsic, viscosity of DNA to its molecular extension.
    Additional Material: 5 Ill.
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Luteochrome isolated from the tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM.) has been shown by HPLC, 1H-NMR and CD spectra to consist of a mixture of (5R,6S,5′R,8′R)- and (5R,6S,5′R,8′S)- 5,6:5′,8′-diepoxy-5,6,5′,8′-tetrahydro-β,β-carotene (1 and 2, resp.). Therefore, its precursor is (5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene (4). This is the first identification of luteochrome as a naturally occurring carotenoid and, at the same time, gives the first clue to the as yet unknown chirality of the widespread β,β-carotene diepoxide. These facts demonstrate that the enzymic epoxidation of the β-end group occurs from the α-side, irrespective of the presence of OH groups on the ring.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 395-400 
    ISSN: 0935-6304
    Keywords: Gas chromatography (GC) ; Fused silica ; Column technology ; Surface modification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for fabricating fused silica capillary columns which have specific surface properties but still retain the excellent strength, flexibility, and resilience of pure fused silica. By using the Modified Chemical Vapor Deposition process (MCVD), typically used for the production of optical fiber lightguides, inorganic dopants such as Al, Nd, Ge, and P can be introduced into the preform-tube by MCVD. Doped columns have a wide range of specific surface properties, and columns with undoped fused silica prepared by MCVD are more chemically inert and less acidic than columns prepared by conventional methods. This paper describes the method for fabricating capillaries and the initial studies to characterize them.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 113-117 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extension of the understanding of properties of films of metals produced on glass surfaces by vacuum evaporation has permitted the fabrication of film-resistance thermometers that with simple instrumentation accurately measure surface or average surface temperatures without altering the geography of that surface. Formerly unknown and unstabled related properties of such films have been classified and may be anticipated or eliminated by recommended experimental procedures. Films of several of the most chemically inert and refractory metals 300 to 3,000 Å. thick have been shown to attain accuracies as high as 0.01°C. for practical periods of time. Their use, which is described, is developing satisfactorily, and the technique and equipment for their preparation are relatively simple.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 890-897 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Data are presented for wall temperatures and heat transfer coefficients for solid-vapor mixtures of parahydrogen and nitrogen flowing in an electrically heated straight tube of length 40 times its diameter. These are interpreted by the application of flat plate, constant property boundary-layer theory to models in which the solid particle geometrical distribution takes on simple limiting forms. The observed enhancement of the heat transfer coefficient over that for gas alone traveling at the same velocity is qualitatively predicted as a function of a dimensionless heat flux, the Sterman parameter qw/ρvUλ.
    Additional Material: 10 Ill.
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  • 7
    ISSN: 0884-3996
    Keywords: Luminometer ; evaluation ; rapid microbiology ; ATP assay ; firefly luciferase ; photometer ; radiometer ; comparison ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An assessment has been carried out of the relative performance of ten instruments for quantification of adenosine triphosphate (ATP) by the firefly luciferase assay. The instruments evaluated were Amersham Amerlite Analyser, Dynatech Tube Luminometer, Dynatech Multiplate Luminometer, Dynatech Camera Luminometer, Hamilton Lumicon, LKB 1250 Luminometer, LKB 1251 Luminometer, Lumac Biocounter M2010A, Turner 20 TD Luminometer and a prototype version of the CLEAR Speed Tech 2000. An 800-fold difference in sensitivity was found between the most sensitive (Lumac, Turner) and the least sensitive (Dynatech Tube) of the conventional instruments. The Dynatech Camera Luminometer which worked on a completely different principle to the other instruments was about 5000 times less sensitive than the best of the photomultiplier tube instruments. The relative sensitivity of the instruments was maintained regardless of whether solutions of ATP in water or trichloroacetic acid extracts of bacteria were analysed. An analysis of 960 ATP bioluminescence assays showed that data obtained from such measurements are normally distributed.
    Additional Material: 5 Ill.
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  • 8
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A system combining ion beam and surface-specific techniques for the analysis of probes exposed in the edge region of the plasma produced by the Joint European Torus (JET) is described. Among examples of the use of the system are the demonstration that 10-40% of the ionic charge flux in the boundary can be due to impurities, erosion and redeposition phenomena can be observed with small probes placed in the plasma boundary, and most of the oxygen observed on collector probes is an artefact resulting from exposure to air.
    Additional Material: 10 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 277-280 
    ISSN: 0268-2605
    Keywords: Ferrocene ; chlorendic anhydride ; flame retardant ; smoke suppressant ; flexible PVC ; 1H NMR spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of ferrocene with chlorendic anhydride (1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid anhydride) under Friedel-Crafts reaction conditions affords a new monosubstituted dervative of ferrocene which has significant flameretardant and smoke-suppressant properties when incorporated into poly(vinyl chloride) (PVC). The monocarboxylic acid from the above reaction undergoes smooth methylation with diazomethane to give the corresponding methyl ester. 1H and 13C NMR spectra of these compounds have been compared with those obtained from similar compounds, namely β-ferrocenoylpropanoic acid and its methyl ester. Distant asymmetric centres in the chlorendic anhydride substituent markedly affect the proton spectra of the ferrocene derivative.
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 8 (1987), S. 265-270 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The fracture properties of two proprietary composite dental restorative materials and a model composite system were studied to determine the effects of filler concentration, exposure to water, and particle/polymer adhesion on subcritical crack propagation. Particle content ranged from 36 to 60 volume percent. The double torsion (DT) test was used to measure relationships between the stress intensity factor (K1) and the speed of decelerating cracks or the rate of loading in dry and wet materials in air at laboratory conditions. Materials with weak particle/polymer interfaces fractured by continuous crack growth in both dry and wet conditions. In dry and wet materials with strong interfaces, continuous cracking also occurred at the low end of the range of speeds observed (10-7 to 10-3 m/s), but under test conditions of high crack speeds unstable (stick-slip) crack propagation was found in dry specimens and in wet model composites with 41 percent vol, filler. Water had a corrosive effect lowering K1c for continuous crack propagation. The exponential dependence of K1c on crack velocity, representing the viscoelastic response of the materials, was positively correlated to the filler concentration and the plasticizing effect of water. Observations on fracture surfaces indicate that low velocity cracks (〈10-5 m/s) propagate through regions of high stress concentrations (interfaces, corners, pores) while at higher crack velocities failure occurs by a combination of interparticle and transparticle fracture.
    Additional Material: 5 Ill.
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