Laboratory thermal alteration

R. Maxwell, J. R. 1989. Laboratory thermal alteration of triaromatic steroid hydrocarbons. Organic Geochemistry, 14, 109-111. 

Alkylated aromatic hydrocarbons are dominant in the unheated samples and are altered to the parent polynuclear aromatic hydrocarbons (PAHs) with limited or no alkylation at higher pyrolysis temperatures. Similar results for aromatic hydrocarbons were reported for laboratory thermal alteration (150-410°C) of kerogen from recent marine sediments (Ishiwatari and Fukushima, 1979). The pattern for the alkylnaphthalene series is shown in Fig. 5. Naphthalene is a trace component in the unheated samples, but becomes the major compound at 500°C. 

The effects of laboratory thermal alteration experiments (low water-rock ratio) on the organic matter of composited Cretaceous black shale samples from DSDP Hole 368 are evident in the following parameters (1) for the hydrocarbons—total yield, formation of PAH and thio-PAH compounds, and increase of Pr/Ph and (2) for kerogen—atomic H/C, HI, 6 C, and vitrinite reflectance (cf. Tables 1 and 2). 

Temperature is a fundamental parameter that definitely influen ces the maturation of sediments. This has been shown empiricalyari T laboratory simulations use it as the "driving force" to induce maturation. In this way, the use of the thermal alteration index in geological materials allows one to qualify (37) source rocks as imature (.temperature below 609C), mature (able to produce oil -if the sediment reached temperatures of 60-1509C) and senile - ja ble to produce gas if the temperature surpassed 1509C. It must be always kept in mind that these transformations occurred along millions of years, and, consequently, all tentatives to simulate these processes in laboratory suffer a severe criticism of their validity. 

Huizinga B.J.,Tannenbaum E., Kaplan I.R. (1987) The role of minerals in the thermal alteration of organic matter—IV. Generation of re-alkanes, acyclic isoprenoids and alkenes in laboratory experiments. Geochim. Cosmochim. Acta 51, 1083-97. 

The observation that thermal alteration of kerogens increases 5org by about 3 permil as H/C is lowered from >1 to 0.1 is also consistent with theoretical arguments (Watanabe et al. 1997), measurements of sedimentary rocks (Simoneit et al. 1981) and laboratory experiments (Lewan 1983 Peters et al. 1981). 

Thermal alteration of Cretaceous black shale from the Eastern Atlantic. Ill Laboratory simulations... 

Vitrinite reflectance data (Rq) for the thermally altered samples (Fig. 11) follow the same trend above and below the sill. The Rq values increase with increasing alteration temperature and plateau above 400°C. The Rq values range from 0.23 to 3.24%, whereas the Rq values of the in situ samples range from 0.25 to 4.81% (Simoneit et al, 1981 Peters et al, 1978, 1983). The laboratory alteration temperatures and corresponding vitrinite reflectance values of the kerogens fit with the temperatures inferred from the in situ Rq data (Peters et al, 1978). The Rq values of the unheated rocks combined for the composited samples (1 and 8) were estimated from the data for the in situ samples. 

Dennis L. W., Maciel G. E., Hatcher P. G. and Simoneit B. R. T. (1982) C nuclear magnetic resonance studies of kerogen from Cretaceous black shales thermally altered by basaltic intrusions and laboratory simulations. Geochim. Cosmochim. Acta 46, 901-907. 

Thermal Properties. Thermal properties include heat-deflection temperature (HDT), specific heat, continuous use temperature, thermal conductivity, coefficient of thermal expansion, and flammability ratings. Heat-deflection temperature is a measure of the minimum temperature that results in a specified deformation of a plastic beam under loads of 1.82 or 0.46 N/mm (264 or 67 psi, respectively). Eor an unreinforced plastic, this is typically ca 20°C below the glass-transition temperature, T, at which the molecular mobility is altered. Sometimes confused with HDT is the UL Thermal Index, which Underwriters Laboratories estabflshed as a safe continuous operation temperature for apparatus made of plastics (37). Typically, UL temperature indexes are significantly lower than HDTs. Specific heat and thermal conductivity relate to insulating properties. The coefficient of thermal expansion is an important component of mold shrinkage and must be considered when designing composite stmctures. 

The mechanical properties of ionomers can be appreciably altered by the manner in which the ionomer is prepared and treated prior to testing. Some of the factors that are influential are the degree of conversion (neutralization) from the acid form to the salt form, the nature of the thermal treatment or aging, the type of counterion that is introduced, the solvent that is used for preparation of thin films, and the presence and nature of any plasticizers or additives that may be present. In the scope of this chapter, it is not possible to provide a complete description of the influence of each of these variables on the wide variety of ionomers that are now commercially available or produced in the laboratory. Instead, one or more examples of the changes in properties that may be induced by each of the processing variables is presented and discussed. 

Because the PCR exponentially copies the target molecule or molecules, amplicon contamination in the laboratory is a serious concern. It is recommended that the mastermix is prepared in an isolated area, such as a PCR station equipped with a UV light. This work area should be exposed to UV radiation after use to destroy any DNA contaminants. The use of dedicated pipets and Altered pipet tips is also recommended. The template DNA should be prepared and added to the reaction in an area that is isolated from the mastermix preparation hood. The thermal cycling and gel electrophoresis should be conducted in a third work area and care should be taken not to introduce amplified PCR products into the mastermix or template preparation work areas. 

The aqueous fluids formed by melting of ices in asteroids reacted with minerals to produce a host of secondary phases. Laboratory studies provide information on the identities of these phases. They include hydrated minerals such as serpentines and clays, as well as a variety of carbonates, sulfates, oxides, sulfides, halides, and oxy-hydroxides, some of which are pictured in Figure 12.15. The alteration minerals in carbonaceous chondrites have been discussed extensively in the literature (Zolensky and McSween, 1988 Buseck and Hua, 1993 Brearley, 2004) and were most recently reviewed by Brearley (2006). In the case of Cl chondrites, the alteration is pervasive and almost no unaltered minerals remain. CM chondrites contain mixtures of heavily altered and partially altered materials. In CR2 and CV3oxb chondrites, matrix minerals have been moderately altered and chondrules show some effects of aqueous alteration. For other chondrite groups such as CO and LL3.0-3.1, the alteration is subtle and secondary minerals are uncommon. In some CV chondrites, a later thermal metamorphic overprint has dehydrated serpentine to form olivine. 

To elucidate some interesting differences between particles that were altered significantly by the thermal history to which they had been subjected and particles that were relatively unaltered, we present data obtained by personnel at the Nuclear Effects Laboratory, who analyzed prompt fallout from the 5-megaton surface coral explosion, Tewa. These samples were obtained within 16 km. of ground zero. 

On the basis of the studies conducted here, it is readily apparent that the presence of minerals can drastically alter the reactivity of the residual char on spent oil shale More detailed quantitative studies of the mineral compositions are necessary in order to be able to assess their importance under typical oil shale processing conditions and will be the subject of future manuscripts from this laboratory. However, at this time, there are several conclusions which can be made. First, the combustion of the char in all six of the shales followed first order kinetics with respect to the oxygen partial pressure and the char available For the western shales this is in agreement with previous works which studied PCM and Anvil Points shales, but it does conflict with the results of Rostam-Abadi and Mickelson (9) who reported second order kinetics for Antrim shale. Secondly, we found that CaO has a catalytic effect on char combustion, most likely due to a chemisorption process And finally we found that Na20, as derived from the thermal decomposition of nahcolite, has a pronounced catalytic effect on the char combustion rate of saline zone shale ... 

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