Mixed Hydrocarbon Research Articles

Experimental Study of Solvent Flooding to Heavy Oil in Fractured Five-Spot Micro-Models: The Role of Fracture Geometrical Characteristics

Abstract The solvent-based process appears to be an increasingly feasible technology for the extraction of heavy oil reserves. However, there is a lack of fundamental understanding of how fracture geometrical characteristics control the oil recovery efficiency in this type of enhanced oil recovery (EOR) technique. In this work, a series of experiments were performed whereby the pure and mixed hydrocarbon solvents (HCS) displaced heavy oil in fractured five-spot glass micro-models. Successive images of the solvent injection process were recorded. The oil recovery factor, as a function of injected pore volume of solvents, was measured using image analysis of the provided pictures. It has been observed that the oil recovery decreased when the fractures' spacing, discontinuity, overlap, and distribution increased. In contrast, the oil recovery increased when the orientation angle, discontinuity-distribution and the number of fractures increased. Also, it has been found that there is an optimum solvent composition, which maximizes the oil recovery. Finally, some pore-level visualization representing the role of asphaltene precipitation during miscible injection was illustrated using these experiments. This study demonstrates the applicability of the micro-models for the fundamental studying of the solvent-based process in fractured five-spot systems, which are used to investigate the effect of fracture geometrical characteristics and their effect on oil recovery. Introduction Heavy oil and bitumen reserves represent a considerable portion of worldwide energy resources. It is estimated that these reservoirs contain six trillion barrels of oil originally in place (OOIP), which is much more than the total conventional oil reservoirs. Great consumption of light oil reserves and their resulting dramatic decline encourages more interest in exploitation of highly viscous oil and bitumen for future energy demands. For optimum conditions, the primary recovery of these reservoirs would not exceed 10% of the OOIP(1). A variety of thermal methods, including cyclic steam stimulation, in-situ combustion and steam assisted gravity drainage are currently being applied for extraction of these crudes. As far as the reservoir's oil is heated, the main fraction of thermal energy is used up in heating the formation itself. For the reservoirs with a thin pay zone, bottom water zone and/or overlying gas zone, excessive depths, low thermal conductivity of rock matrix, high water saturation, etc., the economical applicability of thermal methods is doubtful. With respect to current available recovery technologies, these reservoirs are categorized as problematic reservoirs(2,3).

An <i>in vitro</i> Assessment on the Efficacy of Clay-Based Formulated Cells of <i>Pseudomonas</i> Isolate UTAR EPA2 for Petrol Degradation

Problem statement: Application of free-cell forms is usually impractical to achieve satisfactory bioremediative effect because the microbes are encumbered by the biotic and abiotic stresses from the environment. Approach: In this study, a hydrocarbon-degrading bacterium (Pseudomonas isolate UTAR EPA2) was formulated with various combinations of formulative materials, comprising of clay-based carrier materials such as Bentonite (B) and Kaolin (K), enrichment materials such as Non-fat skimmed milk (N) and Sucrose (S) and a UV-protectant agent Para-aminobenzoic acid (P). Formulated cells were treated to sunlight exposure for 6 h to mimic the conditions in the environment prior to testing for their efficacy in degrading petrol, a mixed hydrocarbon substrate. Results: Cells in all formulations including free-cell suspension were able to degrade petrol with a relatively high degradation efficacy of more than 66% even after exposure to sunlight. Degradation efficacy was slightly higher for kaolin-based formulated cells compared to bentonite-based formulations, especially after exposure to sunlight, although their percentages of degradation were not statistically different. Nevertheless, kaolin-based formulations have very low viable cell count especially in formulations with P (KP, KNP, KSP, KNSP). This suggested that aside from viable cells, the physical properties of the clays could have also contributed to the degradation of petrol. Conclusion: For storage purposes and applications in the field, we suggest that the bacterium is formulated with bentonite-based formulations especially using Bentonite (B) clay singly, as relatively high percentage of petrol degradation and viable cell count was achieved with this formulation.

Geochemical constraints on mixed source and hydrocarbon filling process in the Yingjisu Sag, Tarim Basin, Xinjiang

The Yingjisu Sag was petroliferous for normal oil, condensate oil, reservoir bitumen and natural gases. Geochemical studies showed that natural gases in the Yingjisu Sag were a gas mixture consisting mainly of Cambrian pyrolysis gas, Jurassic condensate oil in well Yingnan 2 and normal oil in well Tadong 2, reflecting the characteristics of marine-phase gases and oils, while crude oils in well Longkou 1 demonstrated the characteristics of both marine and terrestrial oils, which were derived from lower algae and higher plants. Jurassic oils from wells Longkou 1 and Huayingcan 1 and Cambrian crude oils from well Tadong 2 were derived mainly from Cambrian-Lower Ordovician source rocks. Jurassic and Silurian reservoir bitumens from well Yingnan 2 were biodegradated, suggesting they are of marine and terrestrial origins. The bitumens have similar geochemical characteristics, which are correlated well with Ordovician crude oils from well Tadong 2 and Jurassic condensate oil from well Yingnan 2. Based on the characteristics of tectonic evolution in this area and the analysis of hydrocarbon accumulation, the constraints on the mixed source and hydrocarbon filling process in the Yingjisu Sag were brought forward.

Organic and inorganic geochemistry of Ljubija siderite deposits, NW Bosnia and Herzegovina

The Ljubija siderite deposits, hosted by a Carboniferous sedimentary complex within the Inner Dinarides, occur as stratabound replacement-type ore bodies in limestone blocks and as siderite-sulfides veins in shale. Three principal types of ore textures have been recognized including massive dark siderite and ankerite, siderite with zebra texture, and siderite veins. The ore and host rocks have been investigated by a combination of inorganic (major, trace, and rare earth element concen- trations), organic (characterization of hydrocarbons includ- ing biomarkers), and stable isotope geochemical methods (isotope ratios of carbonates, sulfides, sulfates, kerogen, and individual hydrocarbons). New results indicate a marine origin of the host carbonates and a hydrothermal- metasomatic origin of the Fe mineralization. The differ- ences in ore textures (e.g., massive siderite, zebra siderite) are attributed to physicochemical variations (e.g., changes in acidity, temperature, and/or salinity) of the mineralizing fluids and to the succession and intensity of replacement of host limestone. Vein siderite was formed by precipitation from hydrothermal fluids in the late stage of mineralization. The equilibrium fractionation of stable isotopes reveals higher formation temperatures for zebra siderites (around 245°C) then for siderite vein (around 185°C). Sulfur isotope ratios suggest Permian seawater or Permian evaporites as the main sulfur source. Fluid inclusion composition confirms a contribution of the Permian seawater to the mineralizing fluids and accord with a Permian mineralization age. Organic geochemistry data reflect mixing of hydrocarbons at the ore site and support the hydrothermal-metasomatic origin of the Ljubija iron deposits.

Modeling an atypical petroleum system: A case study of hydrocarbon generation, migration and accumulation related to igneous intrusions in the Neuquen Basin, Argentina

In the Altiplanicie del Payún area (Neuquen Basin, Argentina), immature source rock sections intruded by up to 600 m thick Tertiary laccoliths show full spectrum maturity aureoles over hundreds of meters from the contacts. Commercial oil accumulations (20–33°API) and oil shows are located along the entire column, both in sandstone/carbonate and fractured igneous reservoirs. A challenging numerical model that included the emplacement of the intrusive bodies, with extreme temperature ranges and unusually short calculation time steps, has been done with the aim to better understand hydrocarbon generation and migration processes related to these thermal anomalies. A 2D petroleum system model achieved satisfactory results when accounting for thermal maturation, oil and gas generation, composition, migration, and known accumulations. This atypical petroleum system is characterized by thermal anomalies lasting thousands of years that are the result of the progressive cooling of the igneous intrusions. Host source rocks were exposed to a wide range of temperatures that varied in time and space generating different maturity products. High generation pressures, source rock fracturation, and convective water flows facilitated migration and mixing of hydrocarbons and the charge of the igneous bodies as they were fractured during thermal contraction. Oil and source rock analyses were done in order to calibrate and support modeling results. Geochemical correlations suggest an in situ generation related to the igneous intrusions. In particular, diamondoids' measurements show mixing processes of high-mature (cracked) with low-mature hydrocarbons. Oils generated and cracked close to the laccoliths and oils generated from more distant source rock sections, less affected by the thermal anomalies, were probably mixed as they migrated towards the igneous bodies and shallower reservoirs. The integration of a wide set of geochemical analyses and recent modeling techniques based upon time and temperature calculation performance enhancements, led to novel insights on this atypical petroleum system.

Modelling the fate of styrene in a mixed petroleum hydrocarbon plume

Severe petroleum hydrocarbon contamination (styrene and the BTEX compounds: benzene, toluene, ethylbenzene and the isomers of xylene) from leaking sewers was detected in a Quaternary aquifer below a chemical plant in the Padana Plain, Italy. From 1994, active pump and treat remediation has been employed. The site is bordered by canals which, in combination with variable pumping rates and groundwater flow directions, control groundwater levels. In this study we sought to determine the fate of styrene at the site within a mixed styrene/BTEX plume where the hydraulic boundaries induced strong seasonal variations in flows. In order to determine the fate of styrene, detailed field investigations provided intensive depth profile information. This information was then incorporated into a staged flow and reactive transport modelling. Three sets of measurements were obtained from sampling multilevel samplers (MLSs) under different hydraulic conditions at the site. These included measurements of BTEX, styrene, all major ions, pH and redox potential. A three-dimensional transient flow model was developed and calibrated to simulate an unconfined sandy aquifer with a variable flow field. Subsequently a reactive, multi-component transport model was employed to simulate the fate of dissolved BTEX and styrene along a selected flow line at the site. Each petroleum hydrocarbon compound was transported as independent species. Different, kinetically controlled degradation rates and a toxicity effect were simulated to explain the observed, selective degradation of pollutants in groundwater. Calibration of the model was accomplished by comparison with the three different sets of measurements obtained from the MLS devices. The results from various scenarios show that the detailed simulation of geochemical changes can be very useful to improve the site's conceptual model.

The Comparative Reactivity Method – a new tool to measure total OH Reactivity in ambient air

Abstract. Hydroxyl (OH) radicals play a vital role in maintaining the oxidizing capacity of the atmosphere. To understand variations in OH radicals both source and sink terms must be understood. Currently the overall sink term, or the total atmospheric reactivity to OH, is poorly constrained. Here, we present a new on-line method to directly measure the total OH reactivity (i.e.~total loss rate of OH radicals) in a sampled air mass. In this method, a reactive molecule (X), not normally present in air, is passed through a glass reactor and its concentration is monitored with a suitable detector. OH radicals are then introduced in the glass reactor at a constant rate to react with X, first in the presence of zero air and then in the presence of ambient air containing VOCs and other OH reactive species. Comparing the amount of X exiting the reactor with and without the ambient air allows the air reactivity to be determined. In our existing set up, X is pyrrole and the detector used is a proton transfer reaction mass spectrometer. The present dynamic range for ambient air reactivity is about 6 to 300 s−1, with an overall maximum uncertainty of 25% above 8 s−1 and up to 50% between 6–8 s−1. The system has been tested and calibrated with different single and mixed hydrocarbon standards showing excellent linearity and accountability with the reactivity of the standards. Potential interferences such as high NO in ambient air, varying relative humidity and photolysis of pyrrole within the setup have also been investigated. While interferences due changing humidity and photolysis of pyrrole are easily overcome by ensuring that humidity in the set up does not change drastically and the photolytic loss of pyrrole is measured and taken into account, respectively, NO>10 ppb in ambient air remains a significant interference for the current configuration of the instrument. Field tests in the tropical rainforest of Suriname (~53 s

Technologies for hydrogen production based on direct contact of gaseous hydrocarbons and evaporated water with molten Pb or Pb–Bi

Results of research aimed at the justification of advanced energy-saving and safe technology of low-cost hydrogen generation have been presented. The technology basis is direct mixing of water and/or gaseous hydrocarbons with Pb or Pb–Bi heavy liquid metal coolants. Its possible applications include the development of small-size hydrogen sources.

Diffusive Sampling of C<sub>7</sub>–C<sub>16</sub> Hydrocarbons in Workplace Air: Uptake Rates, Wall Effects and Use in Oil Mist Measurements

The measurement of semi-volatile hydrocarbons in workplace air is complicated by their readiness to condense to form aerosols or adsorb on to surfaces. The diffusive sampling and analysis by thermal desorption of alkanes up to hexadecane was investigated with the aim of quantifying vapour from petroleum distillate fractions and possibly differentiating particles from vapour in oil mist measurements of light mineral oil-based metalworking fluids. Diffusive uptake rates were measured on Perkin Elmer thermal desorption tube samplers packed with Tenax TA, and the potential for deposition within the tubes was examined. Hydrocarbon vapour was found to adsorb on the oxide layer that can develop on the sampler's internal walls. General measurements of mixed hydrocarbon vapours (i.e. petroleum distillate fractions) should not be unduly affected if concentrations are greater than approximately 5 mg m(-3) and the tubes are in good condition. For the purposes of differentiating light mineral oil mist and vapour from a total hydrocarbon measurement, it is unlikely that measuring the vapour separately could be used to calculate mist concentrations <3 mg m(-3) with sufficient accuracy.

Physical and chemical interactions of hydrogen and water with liquid lead and lead-bismuth

Results of research aimed at the justification of advanced energy-saving and safe technology of low-cost hydrogen generation have been presented. The technology basis is direct mixing of water and/or gaseous hydrocarbons with Pb or Pb-Bi heavy liquid metal coolants. Its possible applications include the development of small-size hydrogen sources.

Synthesis and Electronic Properties SWCNT Sheets

ABSTRACTThe commercial synthesis of carbon nanotube sheets will be described. This process involves the following steps: chemical vapor deposition of long CNTs from mixed hydrocarbon type fuels, creation and stabilization of the catalyst, and a large textile forming device. Movies of the growth process will be presented and described. Further the electronic properties of these textiles will be presented and discussed as: (1) A function of temperature from −4 °K to 500 °C, (2) A function frequency from 0 up to about 30 GHz and (3) In a magnetic field up to 1000 Oe. It is shown that these yarns have semiconductor properties but surprisingly exhibit apparent metallic like conduction high at high frequencies. The thermoelectric behavior of the textiles (and yarns) made of this material will be discussed as will the applications in secondary batteries. A power level of up to three watts per gram for the thermoelectric material has been demonstrated.

Repeated batch cultivation of the hydrocarbon-degrading, micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam

This study reports on the stability of the cells of a heterotrophic green micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam (PUF) cubes during degradation of mixed hydrocarbon substrate, which was composed of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), in 5 successive cycles of repeated batch cultivation at 30 degrees C. Both RND16 cells and mixed hydrocarbon substrate components had been entrapped in PUF cubes through cultivation. PUF-immobilized RND16 degraded n-alkanes almost completely, whereas the strain hardly degraded PAHs in PUFs, rather they accumulated in the matrices. It is noteworthy that this result is strikingly different from that of the free-living cell culture, where RND16 reduced concentrations of both n-alkanes and PAHs. However, PAHs accumulation in the PUFs did not impair the performance of the immobilized alga to utilize n-alkanes. These results suggest that the PUFs harboring RND16 cells could be used repeatedly for selective retrieval of PAHs from oil-polluted waters after preferential biodegradation of n-alkanes by algae.

Depletion of Liver Glutathione Levels in Rats: A Potential Confound of Nose-Only Inhalation

Nose-only inhalation exposure chambers offer key advantages to whole-body systems, particularly when aerosol or mixed aerosol-vapor exposures are used. Specifically, nose-only chambers provide enhanced control over the route of exposure and dose by minimizing the deposition of particles either on the subjects skin/fur or on surfaces of a whole-body exposure system. In the current series of experiments, liver, brain, and lung total glutathione (GSH) levels were assessed following either nose-only or whole-body exposures to either jet fuel or to clean, filtered air. The data were compared to untreated control subjects. Acute nose-only inhalation exposures of rats resulted in a significant depletion of liver GSH levels both in subjects that were exposed to clean, filtered air as well as those exposed to JP-8 jet fuel and to a synthetic jet fuel. Glutathione levels were not altered in lung or brain tissue. Whole-body inhalation exposure had no effect on GSH levels in any tissue for any of the treatment groups. A second experiment demonstrated that the loss of GSH did not occur if rats were anaesthetized prior to and during nose-only exposure to clean, filtered air or to mixed hydrocarbons. These data appear to be consistent with studies demonstrating depletion in liver GSH levels among rats subjected to restraint stress. Finally, the depletion of GSH that was observed in liver following a single acute exposure was reduced following five daily exposures to clean, filtered air, suggesting the possibility of habituation to restraint in the nose-only exposure chamber. The finding that placement in a nose-only exposure chamber per se yields liver GSH depletion raises the possibility of an interaction between this mode of toxicant exposure and the toxicological effects of certain inhaled test substances.

Feasibility of using microbial fuel cell technology for bioremediation of hydrocarbons in groundwater

A single-cell microbial fuel cell (MFC) design was used to study anaerobic microbes that utilize petroleum contaminants as a sole substrate to produce power during remediation. Additionally, we tested various proton bridge designs to physically separate the anode and cathode chambers of a two-cell MFC by ∼ 9 m (∼ 30 ft.). This separation enables the potential use of MFC technology for in situ bioremediation of petroleum hydrocarbons in the groundwater, in which oxygen is usually depleted and oxygen availability only exists at or near the surface. Sustained power generation (as high as 120 mW/m2 cathode) was recorded for ∼ 6 d in a single-cell MFC utilizing a mixture of refinery waste (containing various concentrations of hydrocarbon contaminants) and cell growth media. MFC cell potential (1KΩ external resistance) decreased by ∼ 55% over the length of the 9 m proton bridge with a 6.9% decrease in potential per m of bridge. This preliminary data indicates that using MFC technology (with our modifications) may enhance bioremediation of petroleum contaminants in groundwater under anaerobic conditions. Because oxygen is eventually used as the terminal electron acceptor for anaerobic biodegradation inside an MFC, this technology may be a cost-effective innovation to enhanced biodegradation in groundwater, by substituting or eliminating conventional in situ aeration. To our knowledge, this is the first report on power generation from MFCs utilizing mixed hydrocarbon substrates. In addition, this study is the first to show the applicability of using extended proton bridges for the physical separation of anode and cathode chambers over extended distances that may be encountered in the field.

Crystal-chemical and carbon-isotopic characteristics of karpatite (C24H12) from the Picacho Peak Area, San Benito County, California: Evidences for the hydrothermal formation

Karpatite from the Picacho Peak Area, San Benito County, California, has been characterized as an exceptionally pure crystal of coronene (C24H12) by infrared absorption analysis, Raman scattering analysis, and differential thermal analysis. Furthermore, the crystal structure of karpatite was determined using a single-crystal X-ray diffraction method for the first time. The mineral crystallizes in the monoclinic system, space group P21/a, with unit-cell dimensions of a = 16.094(9), b = 4.690(3), c = 10.049(8) Å, β = 110.79(2)°, V = 709.9(8) Å3, and Z = 2. The structure was solved and Finally refined to R1 = 3.44% and wR2 = 2.65%, respectively. The coronene molecules in the crystal structure of karpatite are all isolated and the intermolecular distances correspond to van der Waals interactions. The coronene molecules have the high degree of aromaticity and no overcrowded hydrogen atoms, both of which avoid a mixing of other polycyclic aromatic hydrocarbons (PAHs) in karpatite. The corrugated arrangement of coronene molecules constituting karpatite prevents intercalation reactions, accounting for the exceptional purity of this mineral.

Mixing and biodegradation of hydrocarbons in the Daerqi oilfield, Baiyinchagan Depression, northern China

Crude oils in the Daerqi oilfield vary greatly in viscosities, including normal, viscous and highly viscous oils. They are also dramatically different in thermal maturity, from immature to mature based on biomarker parameters. According to bulk and molecular geochemical characteristics, crude oils can be classified into three groups in this oilfield. Group I oils are mature and derived from the deeply buried and relatively old source rocks within the Tengger Formation and the second member of the Arshan Formation of early Cretaceous age. Group II oils are immature to marginally mature and derived from the relatively young source rocks that experienced shallow burial within the first member of the Duhongmu Formation of earlier Cretaceous age. Group III oils are mixtures of group I and group II oils, with dominance of the group I oils (>70%). The viscosity is low for the non-biodegraded group I and group III oils (7.1–24 mPa s) but very high for the non-biodegraded group II oils (e.g., 433,104 mPa s for the representative oil Da12O1). The group III oils are similar to the group I oils in gross properties (e.g., gross composition and viscosity), but are similar to group II oils in terms of their molecular maturity parameters. The oil reservoirs are currently at a shallow depth (<800 m), and some oils are heavily biodegraded up to level 4 on the [Peters, K.E., Moldowan, J.M., 1993. The Biomarker Guide: Interpreting Molecular Fossils in Petroleum and Ancient Sediments. Englewood Cliffs, Prentice-Hall, NJ] scale in this oilfield. A peculiar phenomenon is that some of the group I and group III oils have been heavily biodegraded, whereas the group II oils, interbedded with the biodegraded group I and/or group III oils within a narrow interval in the same wells, are not altered by biodegradation. This is possibly due to the low diffusion coefficient of hydrocarbons and isolation to meteoric water percolation for the group II oil columns.

Evidence for large average concentrations of the nitrate radical (NO 3) in Western Europe from the HANSA hydrocarbon database

The nitrate radical (NO 3) was first measured in the atmosphere in the 1970s and suggestions were made that it could play a major role in oxidising many unsaturated hydrocarbons, such as those emitted from the biosphere. Analysis of the hydrocarbon mix over the North Atlantic Ocean suggested subsequently that the influence of NO 3 radical chemistry at night was even more extensive, being on a par with hydroxyl radical chemistry at some times of the year. The paper presents a detailed analysis of an extensive database of many nonmethane hydrocarbons collected at various sites around the North Sea in the mid 1990s during the HANSA project. By comparing the relative rates of oxidation of iso and normal pentane with that of toluene and benzene it clearly shows that the efficiency of NO 3 radical chemistry and hydroxyl radical chemistry over northwest Europe are similar in springtime and predicts an average nighttime NO 3 concentration of the order of 350 pptv, assuming an annual average OH concentration of 0.6×10 6 cm −3. This value is very dependant on the average emission ratios of the different hydrocarbons and values between 200 and 600 pptv are possible. It is much larger than direct measurements made in Europe at the surface, but is of the same magnitude as concentrations measured recently from aircraft in the boundary layer over the northeast USA, and previously in vertical profiles by remote sounding over Europe. A simple analytical expression can be derived to calculate the NO 3 concentration at night with the only variables being ozone and the loss rate of N 2O 5, either to the ground or to aerosol surfaces. The concentrations of NO 3 calculated in this manner are similar to those derived from the analysis of the HANSA hydrocarbon database for typical conditions expected over Europe, but they are very dependant on the efficiency of the aerosol sink for N 2O 5. It is shown that NO 3 oxidation of many unsaturated hydrocarbons can indeed be more efficient than OH oxidation, especially at times of the year outside the summer season. Direct evidence for hydrocarbon oxidation by NO 3 radicals is shown by a series of peroxy radical measurements where the nighttime concentrations can be significantly higher than daytime concentrations in polluted air on occasion. Also the winter/summer (W/S) ratios of many unsaturated hydrocarbons are much lower than those expected from their removal purely by hydroxyl radical chemistry. The consequences of these findings are profound especially as satellite measurements of NO 2, a major precursor to NO 3, suggest that these high average concentrations of several hundred pptv could be widespread over most of the continents. This needs to be confirmed by direct in-situ measurement of nitrate radicals but it suggests a much larger role for NO 3 chemistry in the oxidation capacity of the atmosphere than realised hitherto.

PARP‐1 activation mediates expression of NF‐κB‐regulated pro‐inflammatory mediators in response to JP‐8 jet fuel in alveolar macrophages

Lung alveolar macrophages are critical in the regulation of airway inflammation in response to environmental pollutants. In response to oxidative stress, macrophages produce both reactive oxygen species (ROS) and nitrogen species (RNS), which induce the expression of a wide variety of immune-response genes. We found that a prolonged exposure of rat alveolar macrophages to a non-lethal dose (8 μg/ml) of JP-8 (a hydrocarbon mix) during several time courses induced the persistent expression of IL-1, iNOS, COX-2, as well as cell adhesion molecules (ICAM-1 and VCAM-1). We determined that JP-8 induced the poly(ADP-ribosyl)ation automodification of PARP-1, a coactivator of NF-κB, in alveolar macrophages. PARP-1 is activated in a time dependent manner, which was temporally coincident with the prolonged activation of NF-κB, and with the augmented expression of the pro-inflammatory factors described above. Together, these results demonstrated that an extensive induction of PARP-1 might coordinate the persistent expression pro-inflammatory mediators in alveolar macrophages activated by aromatic hydrocarbons that can result in lung injury of occupational exposure. Supported by the AFOSR Grant FA9550-04-1-0395.

Silicone-coated polymeric membrane for separation of hydrocarbons and nitrogen at sub-ambient temperatures

Permeation performances of pure and mixed nitrogen, ethylene, ethane, propylene and propane were investigated using a polydimethylsiloxane (PDMS) coated polysulfone composite membrane in the temperature range of −20 to 40 °C. The permeances and selectivities strongly depended on the temperature and feed composition at a constant pressure. Propylene and propane plasticized the PDMS coating with decreasing temperature and increasing hydrocarbon concentrations, which led to significantly high permeances for all mixed hydrocarbons. It also caused positive coupling effects for ethane, ethylene and nitrogen in the presence of propylene and propane. Moreover, pure nitrogen permeances or nitrogen permeance as a mixture component always decreased considerably by lowering the temperature. Consequently, all selectivities for the hydrocarbons to nitrogen increased significantly with the decrease of temperature and increase of total hydrocarbon concentration in feed. A systematic analysis of apparent activation energies to verify the experimental results was also presented.

Synergetic effects of cell immobilization in polyurethane foam and use of thermotolerant strain on degradation of mixed hydrocarbon substrate by Prototheca zopfii

The synergetic effects of an immobilized cell system in an oleophilic polyurethane foam (PUF) and use of a thermotolerant strain on degradation of hydrocarbons by colorless green microalga Prototheca zopfii are reported. Two strains of P. zopfii, i.e. thermotolerant RND 16 and non-thermotolerant ATCC30253, were immobilized in PUF to compare their abilities to biodegrade a mixed hydrocarbon substrate (MHS) containing aliphatic and polycyclic aromatic hydrocarbons (PAHs), as a function of temperature. The thermotolerant strain RND 16 degraded MHS at 35°C, while ATCC30253 did not degrade hydrocarbons at temperatures higher than 30°C. Immobilization of P. zopfii in PUF resulted in shortened lag for growth-associated biodegradation of n-alkanes in MHS, the effect of which was most significant in cultures of RND 16 at 25°C. Nevertheless, the decrease in the amount of degraded PAHs was caused by PUF immobilization and the level of this decrease was marked in the cultures of RND 16, in which rate and extent of n-alkane degradation were higher than for ATCC30253.