Obscurant Formulations

Fluorocarbon binders such as polyvinylidene fluoride (PVDF) have been proposed as oxidizers in obscurant formulations [10]. For a formulation similar as the one shown below, the content of polyaromatic compounds in the soot has been determined. Six hundred grams of the payload were burned, and the generated aerosol was collected from the combustion chamber on a filter with a volume flow rate of 2 m h  

20wt% magnesium 27 wt% polyvinylidene fluoride 5 wt% chlorinated paraffln 48 wt% anthraquinone 

Three PAH were detected, which according to the German MAW catalogue are considered carcinogenic A2 benzo[a]anthracene, benzo[a]pyrene and benzofk] fluoranthene, that is, these substances have shown to be carcinogenic in animal testing and could pose similar risk to human (Table 20.4). 

However, taking into account the singularity of the event firing a salvo of smoke rounds for vehicle protection and being exposed to the aerosol for a maximum of 140 s, a person incorporates 3.35 ng benzo[a]pyren, which equals the amount of daily uptake in an urban atmosphere. 

Besides of PAH exposition, particle size of aerosol wiU determine whether it is transported into the alveoli. The above obscurant yields particles with 90% having 

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Both lithium chlorate and perchlorate have been proposed as oxidizers in explosive formulations [131]. Li nitrate/K nitrate/Na nitrate eutectics (23.5/60.2/16.3) have been proposed by Kruse as oxidizers in illuminating flare formulations [132]. Similarly, LiC104 has been proposed as an oxidizer in obscurant formulations with or boron carbide(B4C) or Si. The obscuring power is mainly due to the presence of hygroscopic LiCl in the aerosol. The formulation B/LiC104 (60/40) possesses the best performance [133-135] compared with Si/Li C104 (35/65) and B4C/Li C104 (30/70) formulations. 

The inventor of the geodesic dome, Buckminster Fuller, backed his designs for minimal weight structures with an obscure formulation, structural... 

The use of metal-fluorocarbon pyrolants in obscurant formulations may fulfil two purposes. The basic reaction yields carbonaceous material and metal fluorides. 

In 1980s, a Swedish company studied obscurant formulations based on Mg/PTFE/RP- and chloroprene-type binders [29]. 

The entire formulation of a chemical question can involve a number of issues, some of which are often obscure to the user. Questions such as what components can be substituted at a given atom site, what types of bonds are favorable for a given chemical fragment query (single, double, ring, chain, aromatic, etc.), and should the query contain explicit or implicit substitution, are just a few of the issues facing a user. 

The applicability of the Born-Oppenheimer approximation for complex molecular systems is basic to all classical simulation methods. It enables the formulation of an effective potential field for nuclei on the basis of the SchrdJdinger equation. In practice this is not simple, since the number of electrons is usually large and the extent of configuration space is too vast to allow accurate initio determination of the effective fields. One has to resort to simplifications and semi-empirical or empirical adjustments of potential fields, thus introducing interdependence of parameters that tend to obscure the pure significance of each term. This applies in... 

In general, standardization ol questionnaires and their items helps to simplify quantitative comparisons between individuals and conditions but simultaneously curtails each individual statement and may force it into inappropriate categories. Moreover, allocating the same weight to all the items m a questionnaire, such as all pairs of opposite toms m a semantic differential, may iron out the effects of substances and obscure mterestmg individual effects. A freely formulated description of drug action, be it m oral or written form, should therefore be included m studies of this land... 

The impact, friction and spark sensitivities of pyrotechnic formulations are assessed by the methods given in Chapter 3. The outlines of methods for the determination of burning rate, luminous intensity, IR intensity, and total obscuring power of smoke are given in this section. 

The measurement of screening performance of smokes is important because smoke screens are one of the countermeasures for IR surveillance systems. The performance of smoke formulations is decided in terms of total obscuring power (TOP), yield factor (Y), mass extinction coefficient (a) followed by calculation of obscuration effectiveness (a. Y. p). These parameters are defined in the following manner. 

The quality of a smoke produced by a smoke formulation can be measured in terms of its TOP under standard laboratory conditions. The TOP of a smoke is obtained by dividing the volume of smoke (in cubic meters) produced per kilogram of material by the standard smoke (smoke layer [in meters] necessary to obscure the filament of a 40-watt lamp) and is expressed by Equation 5.27 ... 

As most military smoke systems have limited volume, the effectiveness of the system also depends on the density (p) of the obscurant material. The greater the density, the greater the number of scattering particles available. The overall effectiveness of an obscurant material or formulation at a particular wavelength is given by the Equation 5.30 ... 

Several groups have investigated the effect of surfactants on emitted droplet size. In the early work performed by Polli et al., the surfactant sorbitan trioleate decreased the MM AD of the CFC dexamethasone suspension when added to the formulation (52). A suspension of terbutaline in a CFC system containing sorbitan trioleate surfactant was shown to have little change in emitted particle size when either 2.8 or 14mg/mL of surfactant was added (53). Interestingly, the surfactant had a significant effect on the obscuration (droplet concentration) of the laser diffraction instrument used to determine particle size. Surfactants may lead to an increase in MMAD due to decreased evaporation rates from aerosol droplets. This may occur because of their tendency to associate at the air liquid interface (54). 

Nortestosterone and its derivatives are banned for use in livestock production within tlie European Union, but have been abused as growth promoters in cattle (17). Abuse can be detected by finding injection sites at slaughter and also by monitoring bile and urine for 17 -19-nortestosterone and/or its 17 -epimer, the major metabolite in cattle (18, 19). However, it is known that 17 -19-nortes-tosterone occurs naturally in pregnant cows (20), and 17 -19-nortestosterone is produced in boars (21) and stallions (22). To evade detection of injection sites at slaughter, some producers have used either multiple injections of small volumes at obscure sites or pour-on formulations. 

Several years ago preliminary results in this study were reported and provided good evidence for the reduction of [Co(CO)4] by sodium in liquid ammonia (82). Although the nature of the reduction product remained obscure, it was formulated to contain [Co(CO)3]3- on the basis of infrared spectra and derivative studies. More recently, the first isolation of a satisfactorily pure sample of Na3[Co(CO)3] was accomplished. Formally, the trisodium salt contains [Co(CO)3]3-, an exceedingly rare example of a three-coordinate, 18-electron metal ion. To our knowledge the only previously well-characterized example of such a compound is [Ni(C2H4)3]2, which is formally present in [Li(TMEDA)]2[Ni(C2H4)3] (83). 

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