Tompkins effect

Ammonium chromates and some other solids exhibit aging effects. Material that has been stored for months or years follows a cubic law with respect to time, but fresh materials are about fifth-order. At I99°C (390°F), the Front-Tompkins law was followed. 

The kinetics and mechanism of vacuum decomposition of AgMn04 at 378—393 K [466] are believed to differ from the behaviour of KMn04 in that the effective chain branching coefficient diminishes with time and this leads (Chap 3, Sect. 3.2) to the modified form of the Prout—Tompkins equation... 

Bircumshaw and Edwards [1029] showed that the rate of nickel formate decomposition was sensitive to reactant disposition, being relatively greater for the spread reactant, a—Time curves were sigmoid and obeyed the Prout—Tompkins equation [eqn. (9)] with values of E for spread and aggregated powder samples of 95 and 110 kJ mole-1, respectively. These values are somewhat smaller than those subsequently found [375]. The decreased rate observed for packed reactant was ascribed to an inhibiting effect of water vapour which was most pronounced during the early stages. 

References to a number of other kinetic studies of the decomposition of Ni(HC02)2 have been given [375]. Erofe evet al. [1026] observed that doping altered the rate of reaction of this solid and, from conductivity data, concluded that the initial step involves electron transfer (HCOO- - HCOO +e-). Fox et al. [118], using particles of homogeneous size, showed that both the reaction rate and the shape of a time curves were sensitive to the mean particle diameter. However, since the reported measurements refer to reactions at different temperatures, it is at least possible that some part of the effects described could be temperature effects. Decomposition of nickel formate in oxygen [60] yielded NiO and C02 only the shapes of the a—time curves were comparable in some respects with those for reaction in vacuum and E = 160 15 kJ mole-1. Criado et al. [1031] used the Prout—Tompkins equation [eqn. (9)] in a non-isothermal kinetic analysis of nickel formate decomposition and obtained E = 100 4 kJ mole-1. 

Studies by Braman and Tompkins [98] have shown that nonvolatile methyltin species Me Sniq + (n = 1-3), are ubiquitous at ng/1 concentrations in natural waters including both marine and fresh water sources. Their work, however, failed to establish whether tetramethyltin was present in natural waters because of the inability of the methods used to trap this compound effectively during the... 

Tompkin, R. B., Christiansen, L. N., and Shaparis, A. B. (1978a). The effect of iron on botulinal inhibition in perishable canned cured meat. J. Food Technol. 13, 521-... 

Gyunter et al, decompd approx 6% of Ba(Ns)a with more than half of the decompn product appearing as nitride. This fact was connected with the impact sensitivity of Ba azide. Groocock Tompkins (Ref 24) described a technique for studying the effects of pre-irradiation and of prolonged bombardment with 100 and 200 V electrons on Ba azide at RT... 

The photo-chemical decompn of aq solns of K azide was accompanied by intense UV (emission) (Refs 25,28,33,34, 35)- Tompkins Young (Ref 46) noted that color centers developed and the salt decompd into its ele-metns when freshly pptd K azide was irradiated with UV light. In studying the electrolysis of aq K azide solns, Audubert Racz (Ref 3U observed that low intensity UV radiation appeared. The Raman Effect of both... 

The quantitative description of the migration process and resulting soil contamination profile, including the effect of a continuous and variable aerosol input, may be adopted from ion exchange plate theory as presented by Mayer and Tompkins (9). 

Thermal Decomposition. Wattenburg (Ref 48) observed that NaNs must be heated to 250° before decompn starts and that formation of NajN is a necessary stage in the decompn of NaNj to Na and Na. According to Garner Marke (Ref 69) the decompn in a vac at 257-365° was similar to that of KN3, but the catalytic effect of Na vapor was small. Decompn followed an induction period and then occurred in two or three steps (Refs 89 108). Audubert (Refs 72 80) noted that intense UV radiation was emitted during slow thermal decompn of NaNj and KN, (Ref 71). In a closed system the nature of gas or its absence had no effect but in a moving current of gas UV radiation was more intense (Ref 76). Bonnemay (Ref 100) detd the effect of bases and neutral salts on decompn rate. Thermal decompn of NaN3 has been studied extensively by Yoffe (Ref 131) and by Jacobs Tompkins (Ref 139)... 

McRobert S. P. and Tompkins L. (1985) The effect of transformer, doublesex and intersex mutations on the sexual behavior of Drosophila melanogaster. Genetics 111, 89-96. 

Hua, P., Webster, J. G., Tompkins, W. J., Effect of the measurement method on noise handling and image quality of EIT imaging, IEEE 9th Annual Conference on Engineering in Medicine and Biological Science, pp. 1429-1430 (1993). 

Effects of Radiation. The threshold for decompn of NaN, by electron bombardment is at 11j65 0.2 volt-electrons (Ref 52). Groocock Tompkins (Ref 160) studied the decompn with 100 and 200 v-electrons at RT and found theoretical calcns agreed with exptl results. Muller Brous (Ref 52) found that photochemical decompn occurred at wave lengths below 405 mft at a rate directly proportional to the UV intensity. No relation between energies necessary for electronic and photochemical decompn was apparent. 

There are numerous reports on the biomedical effects of pectin. Antidiarrheic action is the most widely known property, and pectin has been used to treat diarrhea for more than half a century (Malyoth, 1934 Tompkins, 1938). This effect is often followed by an antivomitive action, which in babies improves assimilation and toleration, particularly of dairy products. This is a consequence of some protection and regulation of the gastrointestinal system (Pilnick and Zwicker, 1970). High-methoxyl pectins are often used to treat gastritis and ulcers. Because the stomach walls become covered with a gel-like film after swallowing pectin, a protective effect on the stomach from gastric and biliar hypersecretions occurs (Navarro and Navarro, 1985). 

The first two reactions give sigmoid ur-time curves that are well expressed by the Prout-Tompkins equation. These are believed to involve a branching-chain mechanism. The third process is fitted by the contracting volume equation, possibly due to decomposition through ion-pair evaporation. The thermal stabihty of N02CJ04 is decreased [42] by the incorporation of impurities which increase the mnnber of cation vacancies, whereas the creation of anion vacancies has the opposite effect. 

Zhabrova etal. [151] identified the reactions of nickel, cobalt and copper oxalates ( , = 150, 159 and 129 kJ mol respectively) as redox processes in which there is an autocatalytic effect by product metal on the electron transfer step. The decomposition rate was determined by the area of the reactant and results were fitted by the Prout-Tompkins equation. In contrast, the reactions of magnesium, manganese and iron oxalates (f, = 200,167 and 184 kJ mol ) are not autocatalytic and the area... 

---