High Aromatic Content Research Articles

High levels of monoaromatic compounds limit the use of solid-phase microextraction of methyl tert-butyl ether and tert-butyl alcohol.

Recently, two papers reported the use of solid-phase microextraction (SPME) with poly(dimethylsiloxane)(PDMS)/Carboxen fibers to determine trace levels of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (tBA) in water. Attempts were made to apply this technique to the analysis of water samples containing high levels of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXsTMBs) as would be expected at leaking underground storage tank sites. It was found that when the sample contained total aromatic compounds above 1 ppm, the response of the internal standards, deuterated MTBE and tBA, dropped by more than 65%. As this decrease in internal standard peak area was unacceptable, a static headspace method was used instead. This headspace method was used successfully to analyze groundwater from 670 monitoring wells at 74 service stations located in the northeast United States. In these monitoring wells, 30% of the samples contained total BTEXsTMBs above 1 ppm. If the SPME method was used to analyze these samples, dilution of more than 200 samples would be required to minimize the adverse matrix effect that high aromatic content had on the internal standard peak area.

A MOLECULAR MECHANICS-DENSITY FUNCTIONAL STUDY OF THE ADSORPTION OF FRAGMENTS OF ASPHALTENES AND RESINS ON THE (001) SURFACE OF Fe2O3

A combination of Molecular Mechanics and Density Functional Theory allowed the calculation of the charge distribution and the adsorption energy on the (001) surface of hematite (α—Fe2O3) of a set of twelve molecules that represent fragments of resins and asphaltenes. The results showed that no covalent bond was formed with the inorganic surface upon adsorption, which indicates that physisorption instead of chemisorption takes place. In aromatic hydrocarbons, the adsorption energy was found to be proportional to the molecular surface, which indicates the main role, played for the van der Waals forces in the adsorption of these molecules. For 2-substituted naphthalenes, the energy decreased with the increase in the length of the alkyl chain. This decrease was related to the gain in deformation energy of the alkyl chain that was required by the adsorption process. The aromaticity and the H/C ratios were found to be good indicators of the ability of the molecules to be adsorbed on the hematite surface. In particular, molecules with high aromaticity and low H/C ratio show high adsorption energy. This result can explain the experimental finding of a high content of high aromatic and low hydrogen content molecules found in asphaltenic deposits extracted from wells. Substitution of the central ─CH2─ group by N─H, O or S at the five-member ring in fluorene produced complex changes in the adsorption energies. In some these molecules, the atoms protruding from the molecular plane produced reduced adsorption energies.

Chemical and Biochemical Properties of Humic Substances Isolated from Forest Soils and Plant Growth

To investigate the relationships among litter composition and 13C–nuclear magnetic resonance spectra (13C–NMR), we studied δ13C values and biochemical activities of the humic constituents extracted from the Ah horizons of two undisturbed forest soils, located in a unique climatic area under different vegetative covers, Pinus mugo T. and Pinus sylvestris L. The two litters differed greatly in composition, while the 13C–NMR spectra of the humic substances extracted from the two Ah horizons were similar. The 13C–NMR spectra of the low molecular humic size (LMS) 1–2 revealed high aromatic and carboxylic contents and low aliphatic and carbohydratic ones. The total humic extracts (TQ) 1–2 and the high molecular humic size (HMS) 1–2 exhibited an opposite trend. The δ13C values of the humic fractions ranged from −24.96 to −25.84‰, indicating an advanced stage of humification. The biochemical activities of the humic fractions were studied by evaluating the invertase, peroxidase, and esterase activities in Pinus mugo and Pinus sylvestris seedling roots grown in the presence of their humic matter. These forest species were differently affected by their humic substances. In particular, the Pinus sylvestris humic matter, endowed with a higher indoleacetic acid (IAA) content, positively influenced all the enzymes tested in Pinus sylvestris seedlings, while the Pinus mugo humic matter only increased the peroxidase activity in its seedlings. The plant species differ in their capacity to respond to biological humus activity, which is reflected in their natural distribution.

Geology, Compositional Heterogeneities, and Geochemical Origin of the Yacheng Gas Field, Qiongdongnan Basin, South China Sea

The Yacheng gas field is located in the footwall of the No. 1 fault, the boundary fault between the Yinggehai and Qiongdongnan basins. The main reservoir is the fan-delta sandstones in the Lingshui Formation. The seals are Meishan For m ation shales near the No. 1 fault and Lingshui Formation shales away from the No. 1 fault. All strata are normally pressured in the gas field except for the Meishan Formation. The Meishan Formation is overpressured near the No. 1 fault in the gas field and in the adjacent Yinggehai Basin. Away from this fault into the Qiongdongnan Basin, the overpressure diminishes. An obvious thermal anomaly occurs below 3600 m in the gas field. This anomaly, characterized by an abrupt increase in drill-stem test and fluid-inclusion homogenization temperatures, vitrinite reflectance (Ro), and Rock-Eval Tmax, and by an abnormally low temperature/Ro/Tmax gradient, diminishes away from the Yinggehai Basin. The gases and condensates have abnormally high aromatic hydrocarbon contents and show obvious heterogeneities. Away from the No. 1 fault, the C2+ hydrocarbon content and C2+/SCn increase; carbon dioxide content decreases; d13C values for methane, ethane, and carbon dioxide become lighter; the heptane and isoheptane values decrease; and the relative contents of aromatic hydrocarbons, both in C6/C7 light hydrocarbons and in the condensates, decrease. Such heterogeneities reflect the reservoir-filling process and origin of the gas field. The gas field was charged from both the Qiongdongnan and the Yinggehai basins. Hydrocarbons sourced from the Qiongdongnan Basin have relatively low maturities, whereas hydrocarbons from the Yinggehai Basin have relatively higher maturities and seem to have been in association with hydrothermal fluids. The hydro thermal fluids from the Yinggehai Basin, in which methane, ethane, carbon dioxide, and especially aromatic hydrocarbons dissolved under the high-temperature and high-pressure subsurface conditions, migrated along the No. 1 fault and caused the abnormally high concentration of aromatic hydrocarbons, as well as the thermal anomalies in the gas field, especially near the No. 1 fault.

Results of long-term experimental carcinogenicity studies of the effects of gasoline, correlated fuels, and major gasoline aromatics on rats.

Unleaded gasoline, with high aromatic content, leaded gasoline, gasoil (diesel), kerosene, toluene, xylenes, ethylbenzene, and 1,2,4-trimethyl-benzene were submitted to long-term experimental carcinogenicity bioassays. The mixtures and the compounds were administered by stomach tube, in olive oil, once daily, 4 days weekly, for 104 weeks, to male and female Sprague-Dawley rats. The animals were kept under control until the end of the experiments. With varying degrees of evidence, all the tested materials were found to increase the total number of malignant tumors and of some site-specific tumors. They must therefore be considered carcinogenic. On the basis of our results the rank of carcinogenic potency of the tested aromatic hydrocarbons increases in the following order: 1,2,4-trimethylbenzene, ethylbenzene, xylenes, toluene (benzene).

Photophysics of Carbazole-Containing Systems. 2. Fluorescence Behaviour of Poly(N-Vinyl Carbazole) and N -Vinyl Carbazole/Methyl Acrylate Copolymer Films

The fluorescence behaviour of thin films of poly( N-vinyl carbazole), PNVCz, and a series of N-vinyl carbazole/methyl acrylate, NVCz/MA, copolymers has been investigated using both steady-state and time-resolved emission techniques. The fluorescence of PNVCz at 298 K is dominated by emission from two excimeric traps. Trap I has the conventional ‘sandwich’ structure formed from two fully overlapped aromatic rings. The other (trap II) is a species involving two partially overlapped carbazole substituents. The fluorescences of the NVCz/MA copolymers contain contributions from unassociated or monomeric carbazoyl excited states which increase in prominence as the aromatic content of the system is reduced. The influence of intermolecular interactions in creating excimer traps is apparent: even at a carbazole content of 8.3 mol%, excimer emission is evident. In PNVCz and copolymers of higher aromatic contents, the microtacticity of the macromolecule exerts a dominant influence upon the photophysical behaviour of the bulk polymer despite the moderating effects of intermolecular interactions between chromophores. As the temperature of the system is reduced, the contribution from trap II to the overall fluorescence from the polymer films increases relative to that made by emission from trap I. At 77 K, the fluorescence of PNVCz contains a significant contribution from trap II emission. At 298 K, fluorescence from the conventional excimer, trap I, dominates the steady-state emission spectrum. On the basis of observations upon time-resolved fluorescence data, it is proposed that restrictions to the reorientation of carbazole substituents which occur at low temperature serve to inhibit the conversion of a proportion of the trap II sites into fully overlapped excimers, thereby reducing depletion of the trap II population. Implicit to this explanation of the photophysical characteristics of PNVCz and the higher content NVCz/MA copolymers, is the belief that the high concentration of excimer-forming trap sites mitigates against significant energy migration between carbazole substituents which might otherwise populate the excimer traps. These observations are of importance to considerations of the photoconductivity displayed by polymers derived from NVCz.

Oxidation of mineral base oils of petroleum origin: The relationship between chemical composition, thickening, and composition of degradation products

AbstractThe aim of this study was to improve understanding of high‐temperature oxidation of base oils used in automobile engine oil formulations. Various oils were investigated: oils from the Middle East and the North Sea, with high and low aromatic and sulphur contents respectively; a hydro‐isomerised polyalphaolefin oil with no aromatic or sulphur content; and a hydrocracked oil of intermediate composition.The influence of the aromatic and sulphur content and composition of the oils on thermo‐oxidative degradation is investigated. These compounds give base oils natural protection from oxidation, but, under severe oxidation conditions, in the presence of a catalyst such as iron, which is always present in an engine, they become precursors of deposits.The action of two types of additive, radical inhibitors and hydroperoxide decomposers, was studied through oxygen consumption and thin‐film oxidation tests.The oxidation products were identified; these provide insight into the degradation processes of the compounds during oxidation. They show too the influence of these processes on the formation of oxidised volatile species, on the increase in viscosity of the oil, and on the formation of oxidised species of high molar mass which, as they condense, contribute to the formation of insoluble compounds and deposits.

Influence of type of vacuum residue on the catalytic coprocessing of a demineralized Catalan lignite

The catalytic coprocessing of a demineralized Catalan lignite under a hydrogen atmosphere was studied. Two vacuum residues with different asphaltene contents were tested as solvents. The experimental results show that the residue with the lower content of both asphaltenes and aromatic oils yields poor coal conversion and oil production as well as low-quality products. The catalysts used do not seem to have any significant influence on these results. The residue with the higher aromatic content gives higher conversions under catalytic conditions. This proves the importance of the aromatic compounds for the mechanism of coal radical stabilization with molecular hydrogen.

Solid-State 13C MAS NMR Studies of Hyper-Cross-Linked Polystyrene Resins

13C CP/MAS NMR techniques have been used to evaluate the structure of four hyper-cross-linked polystyrene resins. Single-pulse excitation (SPE) 13C spectra have allowed the various types of carbon atoms present in the resins to be quantified, and similarly 1H CRAMPS spectra have facilitated quantification of the various hydrogen atom types. Two hyper-cross-linked resins prepared by exhaustive methylene bridging of conventional lightly cross-linked styrene−divinylbenzene resins have very high quaternary aromatic carbon contents. These can be explained adequately only if very high levels of double methylene bridging of aromatic groups occurs. Approximately 10% of aromatic groups also retain a chloromethyl group from incomplete methylene bridging. Two further hyper-cross-linked resins reportedly prepared from conventional heavily cross-linked divinylbenzene (55% technical grade) resins appear in one instance to exploit residual unreacted double bonds (and possibly additional divinylbenzene) to generate the secondary cross-links, and in another to use SOCl2/Lewis acid to introduce very high levels of sulfoxide secondary cross-links. Dynamic NMR experiments suggest that the latter two hyper-cross-linked species retain more flexibility and mobility than those prepared via more conventional methylene bridging techniques.

Organic facies and maturation of Jurassic/Cretaceous rocks, and possible oil-source rock correlation based on pyrolysis of asphaltenes, Scotian Basin, Canada

This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.

Influence of pressure and the presence of water on the evolution of the residual kerogen during confined, hydrous, and high-pressure hydrous pyrolysis of Woodford Shale

This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.

Organic facies and maturation of Jurassic/Cretaceous rocks, and possible oil-source rock correlation based on pyrolysis of asphaltenes, Scotian Basin, Canada

This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.

Chapter 28 Trace amines in hepatic encephalopathy

In 1971 Fischer and Baldessarini proposed the hypothesis that hepatic encephalopathy (HE), a neuropsychiatric syndrome associated with hepatic dysfunction, could result from the direct decarboxylation of amino acids leading to trace amines such as tyramine and octopamine which could then act as false neurotransmitters. This was supported by the observation that the clinical symptoms of HE appeared to improve following treatment with L-Dopa, which cannot be metabolized to either of these trace amines. In addition to serum and urine levels of octopamine correlating roughly with the grade of clinical HE, levels of octopamine were also significantly increased in rat brain following coma induced by hepatic devascularization and in portacaval-shunted rats fed high aromatic amino acid content diets. This hypothesis was questioned, however, given the lack of observable adverse behavioural effects following treatments with octopamine. Finally, the equivocal results of a limited number of clinical trials (using L-Dopa) argued against a direct intervention by catecholamine-like trace amines in HE. An alternative hypothesis was advanced by Sourkes in 1978 implicating increased tryptophan metabolism as a factor in the etiology of HE. Hepatic dysfunction in humans alters CNS concentrations of tryptophan which correlate well with levels of the tryptamine metabolite indoleacetic acid (IAA). Furthermore, regional densities of [3H]tryptamine receptors in HE patient brain tissue are significantly decreased. These data support a pathophysiologic role for tryptophan and its neuroactive trace amine metabolite tryptamine in HE.

Urban ozone air quality impact of emissions from vehicles using reformulated gasolines and M85

The urban ozone air quality impact of exhaust emissions from vehicles using reformulated gasolines and flexible/variable-fuel vehicles using M85 has been studied using emissions data from the Auto/Oil Air Quality Improvement Research Program and a single-cell trajectory air quality model with two different chemical mechanisms (the updated version of Carbon-Bond-IV (CB4) and the LCC mechanism). Peak ozone concentrations are predicted for each fuel for all combinations of the following ambient conditions: low and high atmospheric dilution or mixing height, four NMOG/NO x ratios, two each of the initial NMOG concentration, the vehicular contribution to the ambient air, and the NMOG composition of the initial ambient mixture. The ozone impact of a fuel dependent strongly on the atmospheric dilution and NMOG/NO x ratio of an area. The differences in ozone impact among fuels are limited under the condition of high atmospheric dilution and a high NMOG/NO x ratio. The ozone-forming potentials (OFPs) for the exhaust emissions based on the maximum incremental reactivities (MIRs) for various fuels are generally well correlated with model-calculated peak ozone levels at a low NMOG/NO x ratio. These OFPs can serve to separate out fuels with rather different reactivities, but not fuels with comparable reactivities. Model-calculated ozone levels for various fuels based on CB4 and LCC mechanisms are relatively well correlated at low NMOG/NO x ratios, but much less so at higher ratios. Fuels with a high aromatic content, including high-toluene fuels, tend to be ranked more favorably by CB4 than by LCC. On the other hand, M85 is ranked more favorably by LCC than by CB4. Fuels with a low 90% boiling point and a low content of aromatics and olefins are generally less reactive. M85 would be an attractive fuel if the formaldehyde emissions could be curtailed significantly.

One- and two-stage coprocessing of coal and petroleum residues

The potential of two atmospheric and three vacuum petroleum residues as feedstocks for coprocessing with a UK bituminous coal has been assessed. In a simulation of the British Coal Corporation's two-stage liquid solvent extraction process, the residues were first examined as prospective solvents in the extraction stage. Coal conversions varied from about 6-37%, the best yields being obtained from residues with a high asphaltene content or a high (aromatic and polar) content in the maltene fraction. These yields compare poorly with those obtainable with coal-derived solvents. In two cases, catalytic prehydrogenation of the petroleum residue improved conversions to about 65%, but these results were not reproducible. One-stage coprocessing at 450°C and 12 MPa hydrogen pressure was much more successful

Aromatic Hydrogenation Catalysis: A Review

Abstract High aromatic content in diesel fuel has been recognized both to lower the fuel quality and to contribute significantly to the formation of undesired emissions in exhaust gases [1, 2]. Because of the health hazards associated with these emissions, environmental regulations governing the composition of diesel fuels are being tightened in both Europe and the United States, leading to limitations on aromatics [3, 4].

Purification and properties of the fatty acid‐binding VHDL from the hemolymph of the spider Eurypelma californicum

AbstractAn abundant, very high density lipoprotein (VHDL) was isolated from the hemolymph of male and female tarantula Eurypelma californicum. The purification procedure involved density gradient ultracentrifugation and gel permeation chromatography on Bio‐Gel A‐1.5m. The tarantula VHDL has a hydrated density of 1.23 gml−1 and contains 16.5% lipids. The native molecular mass determined by pore limit electrophoresis and gel permeation chromatography was 380 kDa, which differs from the molecular mass calculated for its SDS‐PAGE subunits (110 and 95 kDa, plus 16.5% lipids). The tetrameric structure of the VHDL is discussed. Both the 110 and the 95 kDa subunit are glycosylated, containing 1.8% carbohydrate, indicating that the difference in molecular mass between them is not due to the level of glycosylation. Treatment of VHDL with reducing agents (β‐mercaptoethanol) decreased the apparent molecular mass of the 110 kDa subunit, while the 95 kDa subunit was not affected, indicating the presence of intra‐molecular disulfide bonds in the 110 kDa subunit. Indeed, cyst(e)ine analysis showed that the molecule contains five disulfide bonds persubunit. Both subunits are antigenically similar, as demonstrated by immunoblotting. Amino acid analysis showed that the VHDL has a relatively high aromatic amino acid content, tyrosine, and phenylalanine (14.5%). Phospholipids (46%) and free fatty acids (35%) were the major lipid components of the VHDL, indicating that this protein is the principal free fatty acid carrier in the hemolymph. The capacity of the purified VHDL to accept free fatty acids from the hepatopancreas was demonstrated in vitro. Phosphatidylcholine (60%) and phosphatidylethanolamine (14%) were the predominant phospholipids. The possible multiple role of tarantula VHDL in carrying fatty acids and carbonic anhydrase is discussed. Fatty acid analysis showed that the fatty acids and non‐polar lipids predominantly contain saturated fatty acids, whereas the phospholipids contain unsaturated fatty acids. © 1993 wiley‐Liss, Inc.

Structural investigations of humic substances by IR-FT, 13C-NMR spectroscopy and comparison with a maleic oligomer of known structure

Humic and fulvic acids isolated from an Italian Typic Dystrochrept by conventional means have been investigated by spectroscopic techniques (IR-FT, 13C-NMR). A quantitative 13C-NMR technique was applied. The investigated fulvic acid contains more aliphatic than aromatic moieties. The carboxyl contents of fulvic acid are greater than those of humic acid. In comparison with fulvic acid the humic acid has a higher content of aromatics. The data presented indicate that structural units resembling those of polymaleic acid may be present in fulvic acid but similar structures have not been detected in humic acid.

Enhancement of recombinant protein synthesis and stability via coordinated amino acid addition

In this work, effective feeding schemes that would minimize stress responses to cloned-protein overexpression are investigated. The cloned-protein (chloramphenicolacetyl-transferase, CAT) contains a high aromatic amino acid content, most notably a high phenylalanine content. Experiments performed on Escherichia coli RR1 [pBR329] (constitutive promoter) and E. coli JM105 [pSH101] (inducible promoter) demonstrated that phenylalanine addition increases the rate of synthesis and yield of CAT. A previous study correlating inducer strength with CAT expression in E. coli JM105 [pSH101] indicated that the highest expression rate was accompanied by the highest apparent rate of protein degradation. In this work, the combined addition of isopropyl-beta-D-thiogalactopyranoside (IPTG) and phenylalanine at intermediate levels resulted in substantial increase of CAT synthesis and partial reduction of protein degradation. Furthermore, transmission electron micrographs verified the absence of inclusion bodies, which, along with proteases, were suspected to reduce protein activity. The research demonstrates that significant enhancement in production and stability of heterologous proteins is possible by designing feeding strategies that incorporate knowledge of the interaction between primary cellular metabolism and foreign protein expression.

絶縁油への銅の溶解現象

Solubility of copper in insulating oil depends on sulfur contents and component of insulating oil. As increasing of sulfur contents, the solubility of copper becomes large. When being added di-tert-butylparacrezole and benzotriazole into the insulating oil, solubility of copper becomes small. Evolution of combustible gas is proportional to amount of copper in insulating oil, and type of gas pattern due to results of gas analysis in insulating oil depends on chemical component of insulating oil. In the case of low aromatic content oil, hydrocarbon gas evolves preferentially, but in the case of high aromatic content oil, hydrogen gas evolves preferentially. Although degradation of the insulating oil is effected by solution of copper, breakdown voltage of insulating paper is not falling down.