A PRACTICAL CLASSIFICATION OF KEROGENS RELATED TO HYDROCARBON GENERATION

The present classification systems of kerogens have many shortcomings, especially in respect of amorphous kerogens which have, so far, remained undifferentiated in relation to hydrocarbon generation. Hence, a practical classification method based on density separation, elemental composition and optical characteristics, which discriminatingly identifies kerogens with indications of their hydrocarbon potential, has been developed. The method first divides the whole range of kerogens into liptinite and humic groups. The liptinitic kerogens are subdivided into Hyperliptinites (prolific oil sources); Mesoliptinites (which are oil-prone); Metaliptinites (gas-prone); and Hypoliptinites (having no potential for hydrocarbons). The humic kerogens are similarly divided into subgroups consisting of Hyperhumics (with some gas potential); Mesohumics (mainly gas sources); and Hypohumics (organic materials with no potential for hydrocarbon generation).     

Minimising signal distortion in f.l.f. active filters

A simple method is described which minimises signal distortion in follow-the-leader-feedback (f.l.f.) active filters. The procedure, which is easily implemented on a digital computer, determines the free design parameters of f.l.f. structures such that the signal-level capabilities of the filters are maximised.     

OIL AND GAS ACCUMULATIONS AND THEIR POSSIBLE SOURCE ROCKS IN SOUTHERN ENGLAND

A number of commercial hydrocarbon accumulations, which include oil and gas, are now known in southern England. Investigations into the organic maturity and hydrocarbon potentials of sedimentary rocks in the area suggest that the Jurassic Lias, Oxford Clay and Kimmeridge Clay units are the most probable sources for these hydrocarbon accumulations. The Lias on the southern side of the Purbeck-Isle of Wight Disturbance appears to be the main source of the Dorset oils (Wytch Farm and Kimmeridge Bay) on the bases of adequate maturity, n-alkane distribution, alkane ratios and stable carbon and hydrogen isotope ratios. On the basis of organic maturity, the oil accumulations in the Weald and the adjacent Hampshire areas are considered to be composed of varying contributions of bitumen generated from the three Jurassic source formations.
Application of the modified Lopatin method of basin modelling suggests the Lias in the Weald as the probable source for the natural gas deposit at Godley Bridge in Surrey and predicts a possible Liassic sourced wet-gas field in the Dorset-Isle of Wight area.     

3-Hydroxy-3-methylglutaryl-CoA reductase gene of Gibberella fujikuroi: isolation and characterization

PURPOSE: Cardiovascular disease is a major cause of morbidity and death in non-insulin-dependent diabetes mellitus (NIDDM). While hyperglycemia is clearly related to diabetic microvascular complications, it contribution to large-vessel atherosclerosis is controversial. PATIENTS AND METHODS: We performed an analysis of the association between glycemic control and prevalent cardiovascular disease in 1,539 participants in the NIDDM Patient Outcomes Research Team study who were under usual care in a health maintenance organization. Prevalent cardiovascular disease and its risk factors were identified by self-administered questionnaire. Cardiovascular disease was defined by the presence of coronary heart disease, peripheral vascular disease, and/or cerebrovascular disease. Glycohemoglobin and lipid levels were obtained from a computerized laboratory database. RESULTS: The mean age of participants was 63 years (range 31 to 91); 51% were women. The mean duration of NIDDM was 9 years (range < 1 to 50), 35% took insulin, and 48% took sulfonylureas. Mean glycohemoglobin was 10.6%. Sixty percent had hypertension, 16% currently smoked cigarettes, and the mean total high-density lipoprotein (HDL) cholesterol ratio was 5.7. Fifty-one percent had cardiovascular disease. Cardiovascular disease prevalence remained constant across increasing quartiles of glycohemoglobin for both men and women. In contrast, prevalent cardiovascular disease was associated with established cardiovascular disease risk factors including age (67 versus 59 years, P < 0.0001), hypertension (66% versus 54%, P < 0.0001), current cigarette smoking (17% versus 13%, P < 0.005), and total/HDL cholesterol ratio (5.9 versus 5.6, P < 0.005). Cardiovascular disease was also associated with duration of NIDDM (11 versus 8 years, P < 0.0001). In multiple logistic regression analysis controlling for established cardiovascular disease risk factors and diabetes duration and therapy, glycohemoglobin remained unassociated with cardiovascular disease. CONCLUSIONS: Glycemic control is not associated with prevalent cardiovascular disease in this large population of individuals with NIDDM. Conventional cardiovascular disease risk factors are independently associated with cardiovascular disease and be a more promising focus for clinical intervention to reduce atherosclerotic complications in NIDDM.     

Type-specific serological testing for herpes simplex infection

The effects of reactive oxygen species (ROS) on elastin molecules (tropoelastin) were studied in vitro. ROS generated by ultraviolet A and hematoporphyrin rapidly degraded tropoelastin within 5 min. Their degradative activity was inhibited by the addition of NaN3. Treatment of tropoelastin with copper sulfate/ascorbic acid resulted in degradation of tropoelastin producing fragments of molecular weight 45, 30 and 10 kDa within 30 min. The degradation of tropoelastin was partially blocked by the addition of mannitol. ROS induced by the xanthine/xanthine oxidase system also degraded tropoelastin within 6 h. The degradation was blocked by catalase but not by superoxide dismutase (SOD). ROS generated by copper-ascorbate seems to be unique in that it cleaves relatively specific sites of the tropoelastin molecule. Thus ROS may play a degradative role in elastin metabolism which may cause the elastolytic changes or the deposition of fragmented elastic fibers in photoaged skin or age-related elastolytic disorders.     

A PRELIMINARY EVALUATION OF LOWER AND MIDDLE CRETACEOUS SOURCE ROCKS IN KUWAIT

Large volumes of oil and gas are present in the Arabian-Iranian Basin; however, most petroleum-geological investigations here have concentrated on reservoirs and traps, and there have been few efforts to study potential source rocks. This paper evaluates possible source rocks within the Lower to Middle Cretaceous interval in Kuwait, which is one of the main oil- and gas-producing countries in this region.
Samples of carbonates and shales from formations within the Thamama and Wasia Groups (Lower and Middle Cretaceous) were collected from five locations in Kuwait. These samples were studied using standard organic-geochemical methods (TOC and pyrolysis analysis, elemental analyses of kerogens, density separation, and petrographic analyses using transmitted and reflected light microscopy).
Most of the kerogens in the studied samples fell between Types II and III. The TOC, kerogen type and maturity of the Sulaiy Formation and parts of the Minagish Formation (Lower Cretaceous) indicate that they supplied hydrocarbons to the reservoirs in Kuwait.     

Short-chain phorbol ester constituents of croton oil

Five phorbol diesters, three 4-deoxy-4α-phorbol diesters, two phorbol monoesters, and one 4-deoxy-4α-phorbol monoester were isolated from a commercial sample of croton oil and characterized spectroscopically. Their purification was achieved using combinations of droplet countercurrent chromatography, low-pressure column chromatography over phase-bonded silica gel, and preparative thin layer chromatography. All of these isolates were shown to possess short-chain ester functionalities, with 12-O-tiglylphorbol-13-isobutyrate, 12-O-(2-methyl)butyrylphorbol-13-isobutyrate, 12-O-(2-methyl)butyrylphorbol-13-acetate, 12-O-tiglyl-4-deoxy-4α-phorbol-13-isobutyrate, 12-O-tiglyl-4-deoxy-4α-phorbol-13-acetate, 12-O-(2-methyl)butyryl-4-deoxy-4α-phorbol-13-acetate, phorbol-12-tiglate and 4-deoxy-4α-phorbol-13-acetate being new compounds. A contribution from the Program for Collaborative Research in the Pharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago.     

ORGANIC GEOCHEMISTRY AND SOURCE ROCK CHARACTERISTICS OF THE ZAGROS PETROLEUM PROVINCE, SOUTHWEST IRAN

The Zagros of SW Iran and its continuation into N Iraq forms the tectonised NE margin of the Middle East basin. Sedimentation in the Zagros began in the late Precambrian and continued with comparatively few interruptions until the Pliocene, when strong earth movements affected the area and gave rise to the present day large. elongated NW-SE trending structures. Some of the world's largest structurally-controlled oil fields are located in the Zagros. The most productive pay zone is the Oligo-Miocene Asmari Formation, although significant oil pools are present also in the Cenomanian-Turonian Sarvak limestone and in the Neocomian-Jurassic Khami Group carbonates. Recently, large gas deposits have been discovered in the Permo-Triassic carbonates assigned to the Deh Ram Group. Geochemical studies were carried out five potential source beds of Eocene-Palaeocene (Pabdeh Formation). Coniacian-Neocomian (Garau Formation) and Silurian (Ghakum Formation) age. The results showed that the organic matter in these formations is almost exclusively of marine algal origin, and that the Kazhdumi is the major source of the hydrocarbons in the Asmari and Sarvak reservoirs. The origin of the hydrocarbons in the Khami and Deh Ram reservoirs is at present speculative.     

Longitudinally modulated cryogenic system. A generally applicable approach to solute trapping and mobilization in gas chromatography

This paper describes a novel approach to solute trapping and remobilization. It involves the use of a subambient trap, with a narrow capillary column passing through the cooled region. A mechanism allows for longitudinal movement of the trap relative to the chromatographic column or narrow transfer line through which analytes travel. Either the trap or the column can be moved, and the frequency or manner of relative movement determines the type of result obtained. A series of preliminary studies are described that define the general approach to using this device and demonstrate the unique benefits that may arise from the modulation movement. Significant improvement (reduction) in peak width occurs if the device is placed immediately prior to the detection system, and consequently a great increase in detection limits results. With a 25 cm length of capillary column between the trap and detector, it is calculated that the plate height of dodecane is 0.082 mm, equivalent to 12?100 plates/m. This was found to be much greater than that for dodecane analyzed on a 25 m column. By slow displacement of the column through the trap, it is demonstrated that the solute is trapped in the first 1 cm (or less) of the column located in the cold trap.     

Cloning and characterization of a eukaryotic pantothenate kinase gene (panK) from Aspergillus nidulans

Pantothenate kinase (PanK) is the key regulatory enzyme in the CoA biosynthetic pathway. The PanK gene from Escherichia coli (coaA) has been previously cloned and the enzyme biochemically characterized; highly related genes exist in other prokaryotes. We isolated a PanK cDNA clone from the eukaryotic fungus Aspergillus nidulans by functional complementation of a temperature-sensitive E. coli PanK mutant. The cDNA clone allowed the isolation of the genomic clone and the characterization of the A. nidulans gene designated panK. The panK gene is located on chromosome 3 (linkage group III), is interrupted by three small introns, and is expressed constitutively. The amino acid sequence of A. nidulans PanK (aPanK) predicted a subunit size of 46.9 kDa and bore little resemblance to its bacterial counterpart, whereas a highly related protein was detected in the genome of Saccharomyces cerevisiae. In contrast to E. coli PanK (bPanK), which is regulated by CoA and to a lesser extent by its thioesters, aPanK activity was selectively and potently inhibited by acetyl-CoA. Acetyl-CoA inhibition of aPanK was competitive with respect to ATP. Thus, the eukaryotic PanK has a distinct primary structure and unique regulatory properties that clearly distinguish it from its prokaryotic counterpart.