碳酸盐岩油藏智能水驱规律与机制

基于伊拉克Missan油田Mishrif组孔隙型碳酸盐岩油藏开展长岩心驱替试验、润湿角测定和界面张力测定试验,研究碳酸盐岩油藏智能水驱作用规律与机制。结果表明碳酸盐岩油藏智能水驱中岩石表面润湿性改善与油水相互作用改变协同作用提高采收率,其中润湿性改善影响较大。关键离子类型及质量浓度对润湿性及界面张力影响明显。其中Mg^(2+)和Ca^(2+)促进润湿性和界面张力的改变,随着其质量浓度增加,润湿角和界面张力均先减小后增大,存在最优质量浓度使得润湿角和界面张力最小;Mg^(2+)作用效果强于Ca^(2+)。SO^(2-)_(4)促进关键阳离子对润湿性的影响,抑制其对界面张力的影响,质量浓度越高作用效果越明显。碳酸盐岩油藏智能水驱中SO^(2-)_(4)优先吸附于方解石表面,促进关键阳离子发生多离子交换反应,造成润湿性的转变;随着溶液中离子类型及质量浓度的改变,吸附于油水界面的极性原油分子发生盐溶和盐析作用,影响油水相互作用。

Purification and Characterization of a Versatile Peroxidase from Edible Mushroom Pleurotus eryngii

A versatile peroxidase (VP-Peco60-7 ) was generated and purified from the liquid culture of Pleurotus eryngii. The purification procedure included ammonium sulfate precipitation, ion exchange chromatography, and gel chromatography. The molecular weight and isoelectric point (pI) of VP-Peco60-7 were determined to be approxi-mately 40 kDa and 4.1, respectively. By N-terminal sequence determination and peptide mapping analysis, VP-Peco60-7 was found to be similar to the versatile peroxidase isoenzyme VPL1, which was previously isolated from liquid cultures of the same species. However, the molecular weight and pI of VP-Peco60-7 were different from those of versatile peroxidases of liquid cultures, implying that the VP-Peco60-7 in this study is of a novel type. With 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) as a substrate, the maximal enzyme activity was obtained at 50 °C and pH 3.0. The catalysis of ABTS by VP-Peco60-7 was expressed by the Michaelis-Menten equa-tion. At 50 °C and pH 3.0, the maximum velocity (V max ) was 188.68 U·mg-1 and the michaelis constant (K m ) was 203.09 μmol·L-1 .

Identification of Fucans from Four Species of Sea Cucumber by High Temperature ~1H NMR

Acidic polysaccharide, which has various biological activities, is one of the most important components of sea cucumber. In the present study, crude polysaccharide was extracted from four species of sea cucumber from three different geographical zones, Pearsonothuria graeffei(Pg) from Indo-Pacific, Holothuria vagabunda(Hv) from Norwegian Coast, Stichopus tremulu(St) from Western Indian Ocean, and Isostichopus badionotu(Ib) from Western Atlantic. The polysaccharide extract was separated and purified with a cellulose DEAE anion-exchange column to obtain corresponding sea cucumber fucans(SC-Fucs). The chemical property of these SC-Fucs, including molecular weight, monosaccharide composition and sulfate content, was determined. Their structure was compared simply with fourier infrared spectrum analyzer and identified with high temperature 1H nuclear magnetic resonance spectrum analyzer(NMR) and room temperature 13 C NMR. The results indicated that Fuc-Pg obtained from the torrid zone mainly contained 2,4-O-disulfated and non-sulfated fucose residue, whereas Fuc-Ib from the temperate zone contained non-, 2-O- and 2,4-O-disulfated fucose residue; Fuc-St from the frigid zone and Fuc-Hv from the torrid zone contained mainly non-sulfated fucose residue. The proton of SC-Fucs was better resolved via high temperature 1H NMR than via room temperature 1H NMR. The fingerprint of sea cucumber in different sea regions was established based on the index of anomer hydrogen signal in SC-Fucs. Further work will help to understand whether there exists a close relationship between the geographical area of sea cucumber and the sulfation pattern of SC-Fucs.

Esterification of Free Fatty Acids in Waste Cooking Oil by Heterogeneous Catalysts

Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.

Uptake of Multi-Disperse Starch by Anion Exchangers

Demineralisation plants of power stations are not able to remove organics in all cases to a satisfied degree. The present work focuses on natural organic matter （NOM） and its interaction with anion exchanger and adsorber resins to optimize organics uptake. In this study, four different starches （one of them 14C-labelled） with different molecular size distributions were selected as model substances for the biopolymer fraction of NOM. Their uptake by various anion exchangers and adsorbers was measured in column experiments. Results are discussed in terms of size exclusion, anion exchange, adsorption, and hydrophilic/hydrophobic repulsion. In summary, at neutral pH, starch has been removed preferably by size-exclusion followed by adsorption, whereas anion exchange resins show higher uptake capacities than ＂pure＂ adsorber resins caused by stronger attraction between starch and polar functional groups of the anion exchangers. At acidic pH, the uptake of sulphate, as competitive adsorptive, leads to an earlier starch breakthrough at anion exchangers. Therefore, adsorbers are more effective. It was found that the higher the water content of the resins, the more effective the uptake is.

Role of Na^+/H^+ exchanger isoform-1 in doxorubicin-induced multidrug-resistance HL-60 cell line

Objective: To explore the roles of intracellular pH value (pHi) and sodium-hydrogen exchanger isoform-1 (NHE-1) in the mechanism of multidrug resistance of leukemia cells. Methods: Multidrug resistant cell line HL-60 induced by doxorubicin(DOX) (called as HL-60/DOX cells) and their parent cell line HL-60 were employed as experiment group and control group. The proliferation and chemosensitivity of the cells were studied by MTT assay, and the expression of multidrug resistance protein (MRP) was detected by immol/Lunocytochemistry. Meanwhile, pHi was measured by spectrofluorometery with a fluorescence dye BCECF-AM. Based on the pHi recovery curve after intracellular acid loading, the activity of NHE-1 was analyzed. The expression of NHE-1 mRNA and MRP mRNA were determined by semi-quantitative RT-PCR. Cell apoptosis was observed with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and apoptotic DNA was extracted and electrophoresed. Results: ① The IC 50 values for DOX, MTZ, VCR and homoharringtonine(HT), in HL-60/DOX cells were significantly higher than those in HL-60 cells (P<0.01). HL-60/DOX cells expressed abundant MRP, but HL-60 cells did not. ② pHi of HL-60/DOX cells were significantly higher than that of HL-60 cells(P<0.001). The expression and activity of NHE-1 in HL-60/DOX cells were significantly stronger than those of HL-60 cells. ③After administration of the specific NHE-1 inhibitor dimethyl amiloride (DMA) at a certain range of concentrations, compared with HL-60 cells, the rate of growth inhibition of HL-60/DOX cells increased significantly (P<0.05), the drug-sensitivity of HL-60/DOX cells was significantly sensitive (P<0.01), the expression of MRP and MRP mRNA decreased significantly (P<0.01), the apoptosis rate increased significantly (P<0.01). Conclusion: NHE-1 is involved in the drug-resistant mechanisms of multidrug-resistant HL-60 cells induced by DOX. The specific NHE-1 inhibitor DMA can partly reverse the multidrug resistance of HL-60 cells induced by DOX.