Additives odorants

Munition grade metal carbonyls are typically yellow to dark-red liquids. Production impurities and decomposition products may cause the agents to darken and give them additional odors. 

Munition grade agents are typically off-white to yellow to brown. As the agent ages and decomposes it continues to discolor. Production impurities and decomposition products in these agents may give them additional odors. 

Olfaction is of primary importance for social recognition in mammals, including mice. Thus mice use odors to distinguish sex, social or reproductive status of conspecifics (Brennan and Zufall 2006 Brown 1979). In addition, odors have been shown to facilitate the display of sexual behavior (e.g. Thompson and Edwards 1972) and to induce neuroendocrine responses (e.g. pregnancy block in female mice Brennan and Keverne 1997). 

In either case a pheromone identification should be followed by an investigation of the response of other species to synthetic compounds, blends, isomers, enantiomers, etc., and comparison of the results with the natural interspecific responses or behavior. Additionally, odors from host plants or pheromones of other species may affect the response of members of a species to their pheromones. 

There are many other sources of lAQ contaminants which are considered unusual, yet can be found in most any building. The most common of these is the small kitchenette area found in many office suites. Odors are the primary cause of lAQ complaints where these are found. In addition, odors from a building or tenant cafeteria can create lAQ complaints. 

Additional odorous components, such as 3-ethyl-2,5-dimethylpyrazine, biacetyl, 3-methylbutanal, 2-phenylethanal and others are found in dark rye bread. Toasted bread contains the same compounds that carry the aroma of bread crust and crumb. A key component is again 2-acetyl-l-pyrroHne, other major components are methional, 4-hydroxy-2,5-dimethyl-2H-furan-3-one (furaneol), ( )-non-2-enal and biacetyl, the odour of which resembles butter. 

For a commercial cell, containing 45 lb caibon, and rated at 700 cfm air at an operating efficiency of about 95%, the service life in hours (t) is calculated to be 4.35 x 10 S/MC. Constants of some important atmospheric odorants for use in this equation are given in Table 12-34. The table also gives calculated values for service life based on a concentration of impurity equal to the odor-threshold value. Additional odor-threshold concentration values are given by Wark and Warner (1976). Data obtained on the adsorption of contaminants from air streams in which they are present in low ppm concentrations indicate that generally reported retentivities represent maximum values (Stankovich, 1969). Appreciably lower capacities can be expected when contaminants are present in concentrations near the odor threshold. 

Individuals exist within an environment, and its impact upon the chemical senses becomes obvious with simple testing. Exposure to an odorant results in adaptation to the odorant i.e., individuals lose sensitivity to the odorant often to the point where they can no longer perceive its presence. This is a common, everyday experience. What many individuals fail to appreciate are the broader impKcations of such changes in olfaction. For example, exposure to one odorant may affect sensitivity to other odorants, whether the additional odorant smells similar to the first odorant or not. This is an example of cross-adaptation (see Fig. 17). 

Animals that do not readily accept pelleted feeds may be enticed to do so if the feed carries an odor that induces ingestion. Color development is an important consideration in aquarium species and some animals produced for human food. External coloration is desired in aquarium species. Pink flesh in cultured salmon is desired by much of the consuming pubHc. Coloration, whether external or of the flesh, can be achieved by incorporating ingredients that contain pigments or by adding extracts or synthetic compounds. One class of additives that imparts color is the carotenoids. 

Humidification. For wiater operation, or for special process requirements, humidification maybe required (see Simultaneous HEAT and mass transfer). Humidification can be effected by an air washer which employs direct water sprays (see Evaporation). Regulation is maintained by cycling the water sprays or by temperature control of the air or water. Where a large humidification capacity is required, an ejector which direcdy mixes air and water in a no22le may be employed. Steam may be used to power the no22le. Live low pressure steam can also be released directly into the air stream. Capillary-type humidifiers employ wetted porous media to provide extended air and water contact. Pan-type humidifiers are employed where the required capacity is small. A water filled pan is located on one side of the air duct. The water is heated electrically or by steam. The use of steam, however, necessitates additional boiler feed water treatment and may add odors to the air stream. Direct use of steam for humidification also requires careful attention to indoor air quahty. 

Odors are characterized by quaUty and intensity. Descriptive quaUties such as sour, sweet, pungent, fishy, and spicy are commonly used. Intensity is deterrnined by how much the concentration of the odoriferous substance exceeds its detection threshold (the concentration at which most people can detect an odor). Odor intensity is approximately proportional to the logarithm of the concentration. However, several factors affect the abiUty of an individual to detect an odor the sensitivity of a subject s olfactory system, the presence of other masking odors, and olfactory fatigue (ie, reduced olfactory sensitivity during continued exposure to the odorous substance). In addition, the average person s sensitivity to odor decreases with age. 

Chlorine, a member of the halogen family, is a greenish yellow gas having a pungent odor at ambient temperatures and pressures and a density 2.5 times that of air. In Hquid form it is clear amber SoHd chlorine forms pale yellow crystals. The principal properties of chlorine are presented in Table 15 additional details are available (77—79). The temperature dependence of the density of gaseous (Fig. 31) and Hquid (Fig. 32) chlorine, and vapor pressure (Fig. 33) are illustrated. Enthalpy pressure data can be found in ref. 78. The vapor pressure P can be calculated in the temperature (T) range of 172—417 K from the Martin-Shin-Kapoor equation (80) ... 

Deodorization can be carried out ki batch, continuous, or semicontkiuous systems. Figure 4 shows a typical design for a semicontkiuous deodorizer. The heated ok is passed through a series of trays under vacuum. Steam is passed through the ok through a steam sparge ki the bottom of the tray. Volatiles are carried through the headspace and condensed. In addition to fatty acids and compounds responsible for odor, some tocopherols and sterols are also distilled kito the condensate. The amount of tocopherols distilled depends on deodorization temperature and vacuum. 

Other Additives. To provide and maintain the clarity of clear shampoos, the use of either ethyl or isopropyl alcohol maybe employed. Perfumes are added to make shampoos more pleasing in terms of odor, while dyes are incorporated to give visual aesthetics to the products. Salts of ethylenediaminetetraacetic acid are found to sequester and prevent formation of insoluble alkaline-earth metal salts. 

G-9 Aromatic Petroleum Resins. Feedstocks typically used for aromatic petroleum resin synthesis boil in the approximate range of 100—300°C at atmospheric pressure, with most boiling in the 130—200°C range. The C-9 designation actually includes styrene (C-8) through C-10 hydrocarbons (eg, methylindene). Many of the polymerizable monomers identified in Table 1 for coumarone—indene type cmdes from coal tar are also present in aromatic fractions from cracked petroleum distillates. Therefore, the technology developed for the polymerization of coal-tar cmdes is also appHcable to petroleum-derived aromatic feedstocks. In addition to availabiHty, aromatic petroleum resins offer several advantages over coumarone—indene resins. These include improved color and odor, as weU as uv and thermal stabiHty (46). 

Substances other than enzymes can be immobilized. Examples include the fixing of heparin on polytetrafluoroethylene with the aid of PEI (424), the controUed release of pesticides which are bound to PEI (425), and the inhibition of herbicide suspensions by addition of PEI (426). The uptake of anionic dyes by fabric or paper is improved if the paper is first catonized with PEI (427). In addition, PEI is able to absorb odorizing substances such as fatty acids and aldehydes. Because of its high molecular weight, PEI can be used in cosmetics and body care products, as weU as in industrial elimination of odors, such as the improvement of ambient air quaHty in sewage treatment plants (428). 

Phenol can be oxidi2ed and hence removed, ie, to levels <20 / g/L, from wastewater (248). Moreover, addition of potassium permanganate to the return activated sludge results in reduction of odors issued from the aeration tanks of conventional activated sludge wastewater treatment plants without any change occurring to the microbiology of the system (249). 

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