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  • 1
    Electronic Resource
    Electronic Resource
    Nitrate depletion in the riparian zone and stream channel of a small headwater catchment (1990)
    Springer
    Hydrobiologia 202 (1990), S. 13-26 
    Details
    ISSN: 1573-5117
    Keywords: denitrification ; riparian zone ; stream ; plant uptake ; mass balance ; ground water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mass balance procedure was used to determine rates of nitrate depletion in the riparian zone and stream channel of a small New Zealand headwater stream. In all 12 surveys the majority of nitrate loss (56–100%) occurred in riparian organic soils, despite these soils occupying only 12% of the stream's border. This disproportionate role of the organic soils in depleting nitrate was due to two factors. Firstly, they were located at the base of hollows and consequently a disproportionately high percentage (37–81%) of the groundwater flowed through them in its passage to the stream. Secondly, they were anoxic and high in both denitrifying enzyme concentration and available carbon. Direct estimates ofin situ denitrification rate for organic soils near the upslope edge (338 mg N m−2 h−1) were much higher than average values estimated for the organic soils as a whole (0.3–2.1 mg N m−2 h−1) and suggested that areas of these soils were limited in their denitrification activity by the supply of nitrate. The capacity of these soils to regulate nitrate flux was therefore under-utilized. The majority of stream channel nitrate depletion was apparently due to plant uptake, with estimates of thein situ denitrification rate of stream sediments being less than 15% of the stream channel nitrate depletion rate estimated by mass balance. This study has shown that catchment hydrology can interact in a variety of ways with the biological processes responsible for nitrate depletion in riparian and stream ecosystems thereby having a strong influence on nitrate flux. This reinforces the view that those seeking to understand the functioning of these ecosystems need to consider hydrological phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02208124
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrate depletion in the riparian zone and stream channel of a small headwater catchment (1990)
    Springer
    Hydrobiologia 202 (1990), S. 13-26 
    Details
    ISSN: 1573-5117
    Keywords: denitrification ; riparian zone ; stream ; plant uptake ; mass balance ; ground water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mass balance procedure was used to determine rates of nitrate depletion in the riparian zone and stream channel of a small New Zealand headwater stream. In all 12 surveys the majority of nitrate loss (56–100%) occurred in riparian organic soils, despite these soils occupying only 12% of the stream's border. This disproportionate role of the organic soils in depleting nitrate was due to two factors. Firstly, they were located at the base of hollows and consequently a disproportionately high percentage (37–81%) of the groundwater flowed through them in its passage to the stream. Secondly, they were anoxic and high in both denitrifying enzyme concentration and available carbon. Direct estimates of in situ denitrification rate for organic soils near the upslope edge (338 mg N m−2 h−1) were much higher than average values estimated for the organic soils as a whole (0.3–2.1 mg N m−2 h−1) and suggested that areas of these soils were limited in their denitrification activity by the supply of nitrate. The capacity of these soils to regulate nitrate flux was therefore under-utilized. The majority of stream channel nitrate depletion was apparently due to plant uptake, with estimates of the in situ denitrification rate of stream sediments being less than 15% of the stream channel nitrate depletion rate estimated by mass balance. This study has shown that catchment hydrology can interact in a variety of ways with the biological processes responsible for nitrate depletion in riparian and stream ecosystems thereby having a strong influence on nitrate flux. This reinforces the view that those seeking to understand the functioning of these ecosystems need to consider hydrological phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027089
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrolysis of alkyl cyanoacrylate and ethoxycarbonylpropenoylphosphonate polymers (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1967-1974 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymers of ethyl α-cyanopropenoate (widely known as cyanoacrylate) and dimethyl (α-ethoxycarbonyl)propenoylphosphonate have been hydrolyzed and their rates of degradation to formaldehyde have been compared. The phosphate polymer produced much less formaldehyde than the cyanopropenoate polymer as required for an improved surgical adhesive. In a comparative study, the rate of aqueous hydrolysis of a high molecular weight cyanoacrylate polymer differed from a previous report. The nature and the hydrolytic properties of the end groups in the two types of polymer are discussed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270617
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  • 4
    Electronic Resource
    Electronic Resource
    Spectroscopic analysis and in situ monitoring of impregnation and extraction of polymer films and powders using supercritical fluids (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 541-549 
    Details
    ISSN: 0887-6266
    Keywords: supercritical fluids ; extraction ; impregnation ; organometallic complexes ; FTIR spectroscopy ; photoacoustic spectroscopy ; diffuse reflectance IR spectroscopy ; FT-raman spectroscopy ; polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A range of vibrational spectroscopic techniques are used to monitor supercritical fluid extraction and impregnation of polymers. Impregnation processes of this type show potential as alternative apporaches to the synthesis of polymer based catalysts and new materials. Methods have been devised using conventional Fourier transform infrared spectroscopy for real time monitoring of the extraction and impregnation of polyethylene films using an organometallic complex, CpMn(CO)3 (Cp = η5 - C5 H5) as a spectroscopic probe. Both low and high density powdered polyethylene may be impregnated using supercritical carbon dioxide. The resulting materials are analysed using FTIR photoacoustic spectroscopy, diffuse reflectance infrared spectroscopy and FT Raman spectroscopy to probe both the impregnated bulk of the polymer and surface-coated material. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320315
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  • 5
    Electronic Resource
    Electronic Resource
    Gel permeation chromatography: Physical characterization and chromatographic properties of corning porous glassesPart I of a series on Characterization and Properties of Macromolecules. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 571-588 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Five porous glasses, manufactured by Corning, reputed to have very narrow pore size distributions, have been characterized by mercury porosimetry, nitrogen adsorption-desorption isotherms, and electron microscopy. The characteristics of these glasses as packing materials in gel permeation chromatography have been determined. Using polystyrene solutes and toluene solvent at room temperature, the glasses in series combination of columns are capable of separating molecular weights from a few thousand to several million. These glasses are compared with other available materials for column packings in gel permeation chromatography.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1971.070150306
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  • 6
    Electronic Resource
    Electronic Resource
    Urea-formaldehyde reaction system. An experimental investigation (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 2597-2611 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Batch production of urea-formaldehyde resins at temperatures up to 100°C takes several hours for completion. Reduction of the batch time may be possible with the higher reaction rates obtained at higher temperatures and increased pressures. In order to investigate this possibility, an experimental technique to obtain the necessary kinetic data, without loss of formaldehyde by evaporation, was developed. The results are compared with earlier low-temperature data extrapolated to the present range of interest. The results were interpreted on the basis of the successive reaction of two or three molecules of formaldehyde with a molecule of urea.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1980.070251116
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  • 7
    Electronic Resource
    Electronic Resource
    Gel permeation chromatography: Physical characterization and chromatographic properties of porasilPart II of a Series on Characterization and Properties of Macromolecules. (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 1253-1268 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: PorasilPorasil is the Water Associates registered trademark for a powdered porous silica chromatographic substrate. porous silica has been characterized by the methods of gas adsorption-desorption isotherms, mercury porosimetry, and electron microscopy. The pore structure has been shown to be quite heterogeneous, particularly at the surface of the particles. From the same sample of Porasil, columns were packed and calibrated in a gel permeation chromatograph. The availability of high molecular weight fractions of polystyrene allowed the exclusion limit of these materials to be determined for the first time. The heterogeneous pore structure did not seem to affect the effectiveness of these materials for macromolecular separation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170419
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  • 8
    Electronic Resource
    Electronic Resource
    Texture of some crystalline synthetic polymers by electron microscopy (1953)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 11 (1953), S. 215-220 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The importance of sample preparation is demonstrated with examples of techniques based on (1) evaporation in vacuo, (2) casting from solvent or solvent mixtures, (3) ultrasonic disintegration. Attention is drawn to the “sheaf-like” arrangement of the microfibrils and to other aspects of the texture. There is evidence of periodicities, but these are considered to vary with the preparation, and may be a consequence of the helical arrangement and “rope-like” character of the bundles of microfibrils or of a tendency to form a woven texture.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1953.120110303
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  • 9
    Electronic Resource
    Electronic Resource
    Interpretation of DSC measurements of the degree of fusion of rigid PVC (1989)
    Brookfield, Conn. : Wiley-Blackwell
    Journal of Vinyl and Additive Technology 11 (1989), S. 33-41 
    Details
    ISSN: 0193-7197
    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 , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Differential scanning calorimetric (DSC) measurements can be used to infer the degree of fusion of rigid PVC articles. The preferred method involves annealing of the specimen at 260°C for 5 minutes, to erase all crystalline structures, followed by a 2 day storage at room temperature. New crystalline entities that are formed give use to an endotherm in the DSC heating mode. The magnitude of this endotherm divided by the total endotherm observed to 220°C can be used to estimate the degree of fusion of the specimen. Data from various processes and different cross-sections of extruded pipe are consistent with solvent resistance estimations.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/vnl.730110109
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  • 10
    Electronic Resource
    Electronic Resource
    High-pressure Raman study of CsVO3 and pressure-induced phase transitions (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 57-60 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure dependence of the Raman frequencies of cesium vanadate (CsVO3) was studied using a diamond anvil cell up to 15 GPa. From the abrupt changes in the Raman specta three pressure-induced phase transitions are inferred at 10, 11.5 and 13 GPa. The first phase transition, at 10 GPa, is subtle but affects the V—O bond length. It is believed that this transition is of the same nature as that observed in postassium and rubidium vanadates. The much higher transformation pressure in CsVO3 is attributed to the anomalous compressibility of the Cs+ ion. The second phase transition involves more drastic changes in the high-frequency region. This is attributed to the rotations and distortions in the VO4 tetrahedra which lower the symmetry of the lattice. In the third phase transition, the appearance of broader Raman peaks and the disappearance of the chain deformation modes suggest a partial disorder in the chain structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250220203
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