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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 2716-2724 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experimental study has been conducted to investigate the effects of swirl on the streamwise development of an axisymmetric turbulent mixing layer. The initial boundary layer was tripped well upstream of the lip. All three mean velocities and the six independent components of the Reynolds stress tensor were measured using a rotatable cross-wire probe for three swirl numbers (0, 0.2, and 0.4). The zero swirl case was found to develop as expected, with a linear growth rate and the peak Reynolds stresses approaching constant asymptotic levels. The results show that the swirling mixing layer is affected by the angular momentum instability over almost the whole layer. The effect of the instability is to increase all the peak Reynolds stresses within the mixing layer, with the peaks increasing monotonically with swirl number. The largest increases occurred in the spanwise normal stress and the two secondary shear stresses. A part of the increase in the turbulence stresses is attributed to "extra'' production through terms activated by the angular momentum instability. The thickness and growth rate for the lower swirl rate were found to be comparable to the zero swirl case, while those for the higher swirl rate were increased significantly, in line with the increased Reynolds stresses. This nonmonotonic behavior of the mixing layer growth rate is attributed to the effects of a favorable pressure gradient in the core flow.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 14 (2004), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Indoor air 10 (2000), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Abstract The American Society for Testing and Materials (ASTM) mouse bioassay, which quantifies airway irritation from reduction in the respiratory rate, was used to find evidence for the formation of highly irritating substances in reactions of ozone with terpenes (common indoor volatile organic compounds (VOCs)). No-observed-effect-levels (NOELs) and concentration-effect relationships were established for ozone, (+)-α-pinene and R-(+)-limonene, isoprene, and some of their major reaction products. Reaction mixtures of excess terpene and ozone considerably below their NOEL concentrations resulted in significant upper airway irritation. The reduction of the respiratory rate was from 30% to about 50%, lowest for the α-pinene and highest for the isoprene mixture. Chemical analysis of reaction mixtures by conventional methods showed that readily identified stable products and residual reactants at the concentrations found could not account for the observed reductions of the respiratory rate, assuming additivity of the reaction products. The results suggest that, in addition to known irritants (formaldehyde, acrolein, methacrolein, methyl vinylketone), one or more strong airway irritant(s) of unknown structure(s) were formed. Future indoor air quality (IAQ) guidelines for unsaturated VOCs (e.g., terpenes) and their emission from building products may require the consideration of reactions with oxidants, like ozone. Similarly, effects of ozone-emitting equipment should be re-evaluated. /〉
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  • 5
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Time versus concentration data of selected volatile organic compounds (VOCs) emitted from four pre-conditioned building materials were measured in the Field and Laboratory Emission Cell (FLEC) at three air exchange rates, 171, 342, 684 h−1, respectively, during a period of 240 hours. The materials were a carpet, a linoleum, a water-borne paint, and a sealant. Modeling of the time versus concentration data for two air exchange rates showed that the emission of VOCs from the carpet were best described with a diffusion model in which the diffusion coefficient depends on the concentration gradient for all data (exponential diffusion model), while a reduced data set eliminating initial events also could be described with a first order decay incorporating a sink effect. The paint emission data of the polar semi-VOC, Texanol, could be described with a first order decay model incorporating a sink effect for all three air exchange rates. The emission rate constant doubled by doubling the air exchange rate. The emission data for VOCs from the sealant were best described for all three air exchange rates by the exponential diffusion model. The best model correlation fit was obtained for hexane, but satisfactory results were also obtained for 2-ethylhexanol and dimethyloctanols. The decay results of linoleum did not allow for modeling leading to the conclusion that an internal concentration gradient had not yet been established under the experimental conditions
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 7 (1997), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: Abstract Concentrations of volatile organic compounds (VOCs) measured indoors may exceed their odor thresholds, but are usually far below TLV estimates. Even applying additivity to eye and airway irritation effects, it is difficult to rationalize increased sick building syndrome (SBS) symptoms by exposure to generally chemically inert VOCs in the indoor environment.Several studies suggest that chemical reactions in indoor air are linked with SBS symptoms and the examination of these reactions may be necessary in order to understand the role of VOCs as causative agents of SBS symptoms.The usual evaluation of odor annoyance of VOCs based on odor thresholds should be modified, taking into account the large variation of individual human odor thresholds for single substances, and specific additivity phenomena even at subthreshold levels of VOCs.The conclusion of this review is that chemical reactions between oxidizable VOCs and oxidants, such as ozone and possibly nitrogen oxides, can form irritants which may be responsible for the reported symptoms. Compounds adsorbed to particles may also contribute to SBS symptoms. The individual effects of indoor pollutants may act in concert with temperature and relative humidity. New analytical methods are required to measure the oxidative and reactive species or specific markers thereof in indoor air.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Indoor air 13 (2003), S. 0 
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
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  • 8
    ISSN: 1600-0668
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Medicine
    Notes: The volatile organic compounds (VOCs) emitted from 12 linoleum samples were measured by use of the “Field and Laboratory Emission Cell” (FLEC) with sampling on Tenax TA followed by thermal desorbtion and GC/FID or GC/MS analysis. Major VOCs were alkanals, alkenals and fatty acids. The emissions were measured after 24 h in FLEC and again after one month's storage in a well ventilated room. The emission profiles of hexanal, nonanal and propanoic acid were modeled for four linoleum samples using a new exponential diffusion model. The time required to reach 50% of the odor threshold concentrations in a standard room was from 113 to 2296 hours. The applicability of the diffusion model for modeling long-term emission needs to be further evaluated considering possible continuous oxidative emission.
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytica Chimica Acta 187 (1986), S. 223-231 
    ISSN: 0003-2670
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 72 (1981), S. 291-299 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence of fixation and tissue preparation on the immunohistochemical localization of human fibronectin in gastrointestinal tract tissue has been examined using indirect immunoperoxidase technique. The most optimal staining result with strong intensity and well defined localization was obtained on frozen sections of unfixed material. Nearly identical results with improved morphology were obtained when staining paraffin sections of tissue fixed in 96% ethanol, 96%+1% acetic acid and absolute acetone. All other fixatives tested, 10% neutral buffered formalin, Lillie's AAF, Bouin's fixative, Clarke's fixative, 4% formaldehyde, 4% formaldehyde+ 0.5% cetylpyridiniumchloride (F-CPC), 4% formaldehyde +0.1% glutaraldehyde gave unsatisfactory results. However, proteolytic digestion with pepsin of paraffin sections prior to staining of buffered formalin and F-CPCfixed material gave results comparable with those obtained on unfixed frozen sections as regards definition of the staining whereas staining intensity was decreased in some degree. No improvement was observed when using proteolytic digestion of tissue fixed in other fixatives.
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