A gas chromatographic analysis of light hydrocarbons on a column packed with modified silica gel

A one-meter long column packed with silica gel is used to separate light hydrocarbons. The silica gel has been modified with several kinds of gas chromatography stationary phases. Among these, PEG 2000 shows fairly good effect when using 80-100 meshes silica gel for the separation of mixture of methane, ethane, ethylene, acetylene, propane, propylene and n-, i-butane. The different behavior of silica gel between batch to batch is also found. When silica gel is coated with a small amount of Al2O3 prepared with sol-gel method, better resolution has been observed on a 2-meter column compared with the non-modified silica gel.

流体地球化学：成因、流动和流体-岩石相互作用及塔里木盆地实例研究

Geofluid in sedimentary basins is related to petroleum generation, migration, accumulation and preservation, and is a topic of geological frontier. By integrating the multi-discipline methods of petroleum geochemistry, sedimentology, hydrogeology, petroleum geology and experimental geochemistry, the thesis has carried out experiments of microcline dissolution in solutions with organic acids, crude oil, brines with high total dissolved solids (TDS), and has dealt with Al distribution between the crude oil and the brines after the experiments. Cases for study includes Central Tarim, Hetianhe Gas Field and Kucha forland basin with data containing fluid chemistry and isotopic compositions, thin sections of sandstones and carbonates, homogenization temperatures and salinities of fluid inclusions, isotopic compositions of bulk rock and autigenic minerals. The aims are to elucidate fluid origin and flow in the three areas, effect of hydrocarbon emplacement on diagenesis, and to show occurrence of microbe-mediated, and thermochemical sulfate reduction in the Tarim Basin. Microcline dissolution experiments show that after 100 hour, part of the dissolved Al distributes in the crude oil, and the Al concentrations in the crude oil rise when organic acids are added. The result can be used to explain that most oilfield waters in the Tarim Basin are characterized by less than 3mg/L Al. Crude oil added to the solutions can enhance microcline dissolution, which is also observed in the case - Silurian sandstones with early crude oil emplacement in the Central Tarim. Al and Si have higher concentrations in the experiments of oxalic acid than of acetic acid under the same pH conditions, suggesting that there exist Al-oxalate and Si-oxalate complexes. Presence of acetate can enhance the activity of Ca and Al, but Al concentrations have not been increased significantly due to formation of small Al-acetate complex during the experiments. Relationships between δD and δ~(18)O in conjunction with chemistry of oilfield waters show that the waters are evaporated connate waters, which subsequently mixed with meteoric water, and were influenced by water-rock interactions such as salt dissolution, dolomitization of calcite, albitization of feldspar. In the Hetianhe Gas Field where salt dissolution took place, δD and δ~(18)O values can be used to trace nicely meteoric water recharge area and flow direction, but TDS can not. Part of the waters have high TDS but very light δD and δ~(18)O. When combined with paleo-topography, or fluid potentials, meteoric water is suggested to flow eastward in the Hetianhe Gas Field, which is the same with the Central Tarim. Whist in the Kuche forland basin, meteoric water may have permeated Cambrian-Ordovician strata. Relationship between ~(87)Sr/~(86)Sr and 1/Sr can be used to indicate migration and mixing of brines from carbonate strata (low ~(87)Sr/~(86)Sr ratio but high Sr content), clastic strata (high ~(87)Sr/~(86)Sr ratio but low Sr content) and crystalline basement (high ~(87)Sr/~(86)Sr ratio and heavy δ~(18)O value). Using this approach, it can be found that ~(87)Sr-depleted brine from Ordovician carbonates have migrated up to and mixed with ~(87)Sr-enriched waters from Silurian and Carboniferous sandstones, and that Silurian brines have mixed with meteoric water. In the Kuche forland basin, brines from the Cambrian and Ordovician carbonates have higher ~(87)Sr/~(86)Sr ratios than those from the overlying sandstones, when combined with chemistry, δ~(15)N and ~3He/~4He ratios of the coexisting natural gases, suggesting that the brines were derived from the basement. There exists some debate on the effect of hydrocarbon emplacement on mineral diagenesis. Case-study from Silurian sandstones in the Central Tarim show that quartz has kept overgrowing secondarily when oil saturation was decreased by meteoric water flushing subsequently to hydrocarbon emplacement. Silicon precipitates on the water-wet quartz surface, leading to decreased Si concentration close to the surface. A Si grads can result in Si diffusion, which supplies Si for quartz overgrowth. Hydrocarbon oxidation-sulfate reduction is an important type of organic-inorganic interaction. Not only can it make secondary alteration of hydrocarbons, but generate H_2S and CO_2 gases which can improve reservoir property. Thermochemical sulfate reduction took place at the temperatures more than 125 ℃ to 140 ℃ in the Cambrian-Ordovician carbonates, the products - H_2S and CO_2 gases migrated up to the Silurian, and precipitated as pyrite and calcite, respectively. The pyrite has an average δ~(34)S value close to those of Ordovician seawater and anhydrite, and calcite has δ~(13)C value as low as -21.5‰. In the Hetianhe Gas Field, sulfate reduction bacteria carried by meteoric water flowing eastward may have preferentially depleted ~(12)C of light hydrocarbon gases, and results in heavier δ~(13)C values of the residual hydrocarbon gases and higher molar CO_2 in the natural gases in the west than in the east. Coexisting pyrite has δ~(34)S values as low as -24.9‰.

富硫流体的成因与硫酸盐还原作用研究

Origins of H_2S, thiols, thiophenes in natural gases and sulphur-enriched oils are complicated and thus some debates exist on them. The post-doctoral research is based upon oil- and gas-field data. Cases for study include Triassic Jianglingjiang Formation natural gases, Wolonghe Field, Sichuan Basin, Paleozoic oils and bitumen, Central Tarim, gases reserviored nearby Carboniferious - Ordovician unconformity, Hetianhe Field, Tarim Basin and sulphur-enriched oils in Tertiary reserviors in Jinxian Sag, Bohai Bay Basin. We have carried out analyses on the oils and gases for chemistry, δ~(13)C, δ~(34)S, and molecular composition of biomarkers, analyzed authigenetic pyrite forδ~(34)S, formation water for chemistry and δD and δ~(18)O along with petroleum system and burial history analyses, The aims are to assess the origins of the H2S and authigenetic pyrite, to discuss the possibility of reduced sulphur incorporation into hydrocarbons and to determine the mechanisms of hydrocarbon secondary alteration in the above four cases by comparison. The research shows that the reduced sulphur in the four cases is the result of thermochemical and biological sulphate reduction., TSR and BSR, respectively. No evidence indicates an origin of decomposition of organic matter or mantle - derived H2S in the cases. Elevated H_2S contents (up to 32%) in the Triassic Jialingjiang Formation are considered to result from TSR while relatively low H_2S (up to 2000ppm) in the Hetianhe Field resulted from BSR. However, it is not the case for the Central Tarim where relatively low H2S but abundant authigenetic pyrite occurr. Part of the H_2S in the Central Tarim reservoirs has reacted with iron released from clay minerals to precipitate pyrite. Thus, reduced sulphur δ~(34)S and reservoir temperatures rather than the H2S amount are reliable parameters to distinguish between TSR and BSR. TSR in Sichuan Basin Triassic Jialingjiang Formation and Central Tarim Paleozoic reservoirs are showed to take place at more than 125℃. the H2S and authigenetic pyrite have δ~(34)S close to parent anhydrite. In contrast, BSR in the reservoirs near the Carboniferous - Ordovician unconformity in the Hetianhe Field and in the Tertiary in the Jinxian Sag took place at temperatures less than 80℃with sulphide δ~(34)S as light as -24.9‰ and -12.5‰, anhydrite δ~(34)S as heavy as +26‰and +3 5-+40‰, respectively. Chemistry and isotopic composition of the natural gases change as the result of sulphate reduction. It has been observed that relative composition of light hydrocarbon gases is changed along with a rise in H_2S and CO_2. TSR in the Triassic Jialingjiang Formation and BSR in the Hetianhe Field result in a greater degree of preferential depletion of methane than larger molecular hydrocarbon gases. As TSR or BSR proceeds, hydrocarbon gases evolved to heavier carbon isotope as the result of kinetic isotopic fractionation, i.e., selective anaerobic oxidation of ~(12)C. Using the model of residual methane (Whiticar, 1999) to describe the relationship among the proportion of methane oxidation, isotopic shift and fraction factor, about 30% methane is calculated to have been oxidized during BSR in the western part of the Hetianhe Field. From the above, it can be concluded that in the area where H_2S is abundant, empiricalδ~(13)C -Ro relationships do not work. Sulphate reduction results in a rise in sulphur content, gravity and viscosity of an oil as well as changes in δ~(13)C and δ~(34)S. On special conditions, the reduced sulphur from sulphates might be incorporated into oils, i.e., the increasing sulphur is derived from secondarily reduced sulphur. A positive correlative relationship exists between sulphur content and δ~(34)S in the oils in Paleozoic reservoirs in Central Tarim, indicating that enhanced sulphur is ~(34)S-enriched, originated from TSR. The Jinxian oil with the highest sulphur content has the lightest δ~(34)S, suggesting part of the sulphur in the oil is ~(34)S-depleted, originated from BSR. In the Jinxian oil with increasing sulphur content, asphaltenes shows higher content and more negative δ~(13)C, and saturates shows evidence of biodegradetion and a decreasing content and a positive δ~(13)C shift. Thus, asphaltenes have δ~(13)C values closer to saturates. All the above indicate that the reduced sulphur has been incorporated into biodegradated saturates to generate new asphaltenes with relatively light δ~(13)C of saturates. Thiols and thiophenes in natural gases in the Triassic Jialingjiang Formation may result from reaction of H_2S with hydrocarbon. In the Jialingjiang Formation hydrocarbon gases are dominated by methane thus have a high dryness coefficient and thiols are showed to be positively related to H_2S content, suggesting that the thiols may result from H_2S reaction with short chain hydrocarbons. In contrast, high thiophenes occur in wet gases in Jurassic reservoirs with their source rock from sulphur - depleted type I kerogen, indicating that thiophenes may be a product of reaction of H2S with longer chain hydrocarbons.

Novel Oligo-9,9 '-spirobifluorenes through ortho-Linkage as Full Hydrocarbon Host for Highly Efficient Phosphorescent OLEDs

4-Bromo-9,9'-spirobifluorene is facilely synthesized, and from this precursor, two ortho-linked oligo-9,9'-spirobifluorenes, 44BSF and 24TSF, are constructed. Devices with 24TSF as the full-hydrocarbon host material and Ir(ppy)(3) or (ppq)(2)Ir(acac) as the triplet emitter show maximum external quantum efficiencies of 12.6 and 10.5% for green and red electrophosphorescence, respectively.

Development and application of oxygen permeable membrane in selective oxidation of light alkanes

In this paper, oxygen permeable membrane used in membrane reactor for selective oxidation of alkanes will be discussed in detail. The recent developments for the membrane materials will be presented, and the strategy for the selection of the membrane materials will be outlined. The main applications of oxygen permeable membrane in selective oxidation of light alkanes will be summarized, which includes partial oxidation of methane (POM) to syngas and partial oxidation of heptane (POH) to produce H-2, oxidative coupling of methane (OCM) to C-2, oxidative dehydrogenation of ethane (ODE) to ethylene and oxidative dehydrogenation of propane (ODP) to propylene. Achievements for the membrane material developments and selective oxidation of light alkanes in membrane reactor in our group are highlighted.

A Nanomechanical Device Based on Light-Driven Proton Pumps

In this paper, a hybrid device based on a microcantilever interfaced with bacteriorhodopsin (bR) is constructed. The microcantilever, on which the highly oriented bR film is self-assembled, undergoes controllable and reversible bending when the light-driven proton pump protein, bR, on the microcantilever surface is activated by visible light. Several control experiments are carried out to preclude the influence of heat and photothermal effects. It is shown that the nanomechanical motion is induced by the resulting gradient of protons, which are transported from the KCl solution on the cytoplasmic side of the bR film towards the extracellular side of the bR film. Along with a simple physical interpretation, the microfabricated cantilever interfaced with the organized molecular film of bR can simulate the natural machinery in converting solar energy to mechanical energy.

Evaluation of influence of multiple scattering effect in light-scattering-based applications

The extinction cross sections of a system containing two particles are calculated by the T-matrix method, and the results are compared with those of two single particles with single-scattering approximation. The necessity of the correction of the refractive indices of water and polystyrene for different incident wavelengths is particularly addressed in the calculation. By this means, the volume fractions allowed for certain accuracy requirements of single-scattering approximation in the light scattering experiment can be evaluated. The volume fractions calculated with corrected refractive indices are compared with those obtained with fixed refractive indices which have been rather commonly used, showing that fixed refractive indices may cause significant error in evaluating multiple scattering effect. The results also give a simple criterion for selecting the incident wavelength and particle size to avoid the 'blind zone' in the turbidity measurement, where the turbidity change is insensitive to aggregation of two particles.

A characteristics study on the performance of a 2-stage light gas gun

In order to obtain an overall and systematic understanding of the performance of a two-stage light gas gun (TLGG), a numerical code to simulate the process occurring in a gun shot is advanced based on the quasi-one-dimensional unsteady equations of motion with the real gas effect,;friction and heat transfer taken into account in a characteristic formulation for both driver and propellant gas. Comparisons of projectile velocities and projectile pressures along the barrel with experimental results from JET (Joint European Tons) and with computational data got by the Lagrangian method indicate that this code can provide results with good accuracy over a wide range of gun geometry and loading conditions.

Beam splitter entangler for light fields

We propose an experimentally feasible scheme to generate various types of entangled states of light fields by using beam splitters and single-photon detectors. Two beams of light fields are incident on two beam splitters respectively with each beam being asymmetrically split into two parts in which one part is supposed to be so weak that it contains at most one photon. We let the two weak output modes interfere at a third beam splitter. A conditional joint measurement on both weak output modes may result in an entanglement between the other two output modes. The conditions for the maximal entanglement are discussed based on the concurrence. Several specific examples are also examined.

Reflection and refraction of light at the interface of a uniaxial bicrystal

This paper deals with a theoretical analysis of the reflection and refraction of light at the interface of a bicrystal by use of Maxwell's equations. For a general case, the formulas of Snell's Law and the four Fresnel coefficients for the reflection and refraction of extraordinary light at the interface of a uniaxial bicrystal are derived for the first time, as well as the Brewster angle value. The condition for total reflection is presented and the electromagnetic fields distributions at both sides of a bicrystal are presented when total reflection occurs.

Group velocity of probe light pulse in an open lambda system

The group velocity of the probe light pulse (GVPLP) propagating through an open Lambda-type atomic system with a spontaneously generated coherence is investigated when the weak probe and strong driving light fields have different frequencies. It is found that adjusting the detuning or Rabi frequency of the probe light field can realize switching of the GVPLP from subluminal to superluminal. Changing the relative phase between the probe and driving light. elds or atomic exit and injection rates can lead to GVPLP varying in a wider range, but cannot induce transformation of the property of the GVPLP. The absolute value of the GVPLP always increases with Rabi frequency of the driving light field increasing. For subluminal and superluminal propagation, the system always exhibits the probe absorption, and GVPLP is mainly determined by the slope of the steep dispersion.

Incoherent subharmonic light scattering in isotropic media

Incoherent subharmonic light scattering in isotropic media is a new kind of nonlinear light scattering, which involves single input photon and multiple output photons of equal frequency. We investigate theoretically the dependence of the subharmonic scattering intensity on the hyperpolarizability of molecules and the incident intensity using nonlinear optics theory similar to that used for Hyper-Rayleigh scattering and degenerate optical parametric oscillators. It is derived that the subharmonic scattering intensities grow exponentially or superexponentially with the hyperpolarizability of molecules and the incident intensity. (C) 2004 Elsevier B.V. All rights reserved.