Analysis of bacterial diversity in two oil blocks from two low-permeability reservoirs with high salinities.

The community diversities of two oil reservoirs with low permeability of 1.81 × 10(-3) and 2.29 × 10(-3) µm(2) in Changqing, China, were investigated using a high throughput sequencing technique to analyze the influence of biostimulation with a nutrient activator on the bacterial communities. These two blocks differed significantly in salinity (average 17,500 vs 40,900 mg/L). A core simulation test was used to evaluate the effectiveness of indigenous microbial-enhanced oil recovery (MEOR). The results indicated that in the two high salinity oil reservoirs, one reservoir having relatively lower salinity level and a narrow salinity range had higher bacterial and phylogenetic diversity. The addition of the nutrient activator increased the diversity of the bacterial community structure and the diversity differences between the two blocks. The results of the core simulation test showed that the bacterial community in the reservoir with a salinity level of 17,500 mg/L did not show significant higher MEOR efficiency compared with the reservoir with 40,900 mg/L i.e. MEOR efficiency of 8.12% vs 6.56% (test p = 0.291 > 0.05). Therefore, salinity levels affected the bacterial diversities in the two low permeability oil blocks remarkably. But the influence of salinity for the MEOR recovery was slightly.

Temperature dependence of Raman scattering in bulk 4H-SiC with different carrier concentration.

Raman spectra of three bulk 4H-SiC wafers with different free carrier concentration were measured at temperature from 80 K to 873 K. As temperature increases, Raman peaks of most optical phonon modes show monotonous down shift. An anomalous non-monotonous variation with temperature, was observed in the A(1) longitudinal optical (LO) mode from doped samples. Two methods of theoretical fitting, one-mode (LO-plasma coupled (LOPC) mode) and two-mode (A(1)(LO) + LOPC) fitting, are employed to analyze this anomalous phenomenon. Theoretical simulations for temperature dependent Raman spectra by using two methods are critically examined. It turns out that one-mode method conforms well the experimental results, while two-mode method is untenable in physics. The non-monotonous variation of blue-red shifts with temperature for LOPC mode from doped 4H-SiC could be explained by the influence from ionization process of impurities on the process of Raman scattering. A quantitative description on temperature dependent Raman spectra for doped 4H-SiC is achieved, which matches well to experimental data.

[Study on the mechanism of energy transfer between acridine orange and rhodamine 6G in micelles of dodecyl benzene sodium sulfonate].

Applying Förster theory, the energy transfer between acridine orange (AO) and rhodamine 6G (R6G) was investigtaed. It was found that in the solution of dodecyl benzene sulfonic acid sodium (DBS), effective energy transfer can occur between AC and rhodamine 6G even when the concentration of the dyes is very low. The mechanism of energy transfer between AO and rhodamine 6G was studied. When the energy transfer occurs, the fluorescence of AO is quenched, the type of quenching is static. Based on the mechanism of Förster energy transference, the thermodynamic parameters, enthalpy change (deltaH) and entropy change (deltaS), were calculated according to Van't Hoff equation, which indicates the acting force between AO and R6G. The transfer efficiency of energy and the distance between AO and R6G were found. It is indicated that the course of action is single static quenching.