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 x 10 \u273 and 2.29 x 10 \u273 1/4m 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 \u3e 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

Design, Synthesis, and Biological Evaluation of Novel Tetrahydroacridin Hybrids with Sulfur-Inserted Linkers as Potential Multitarget Agents for Alzheimer’s Disease

Alzheimer’s disease (AD) is a complex neurodegenerative disease that can lead to the loss of cognitive function. The progression of AD is regulated by multiple signaling pathways and their associated targets. Therefore, multitarget strategies theoretically have greater potential for treating AD. In this work, a series of new hybrids were designed and synthesized by the hybridization of tacrine (4, AChE: IC50 = 0.223 μM) with pyrimidone compound 5 (GSK-3β: IC50 = 3 μM) using the cysteamine or cystamine group as the connector. The biological evaluation results demonstrated that most of the compounds exhibited moderate to good inhibitory activities against acetylcholinesterase (AChE) and glycogen synthase kinase 3β (GSK-3β). The optimal compound 18a possessed potent dual AChE/GSK-3β inhibition (AChE: IC50 = 0.047 ± 0.002 μM, GSK-3β: IC50 = 0.930 ± 0.080 μM). Further molecular docking and enzymatic kinetic studies revealed that this compound could occupy both the catalytic anionic site and the peripheral anionic site of AChE. The results also showed a lack of toxicity to SH-SY5Y neuroblastoma cells at concentrations of up to 25 μM. Collectively, this work explored the structure–activity relationships of novel tetrahydroacridin hybrids with sulfur-inserted linkers, providing a reference for the further research and development of new multitarget anti-AD drugs

ENCOUNTERING CHINESE PERFORMING TROUPES IN NANYANG: TRANSNATIONAL CIRCULATIONS, DIASPORIC LOCALIZATIONS AND CHANGING CHINESENESS, 1850S-1980S

Ph.DDOCTOR OF PHILOSOPHY (FASS

The Study on Dynamic Characteristics of Twin-Screw Compressor Rotor

In the working process of twin-screw compressor, the rotors are subjected to multiple physical effects of the gas temperature, pressure and force, and presents a periodic change. In this paper, three-dimensional Computational Fluid Dynamics (CFD) simulation of screw compressor is carried out, and the characteristics of temperature distribution, pressure distribution and gas force distribution on the rotors’ surface are studied. Firstly, the rotor domain, suction and exhaust face grids are generated by TwinMesh, and then they are imported into the CFX calculation model. Through the fluid-structure interaction analysis and calculation, the strain shape of the screw rotor under the multiple alternating physical action of gas temperature, pressure and force is analyzed, and the deformation of the rotor structure caused by the pressure and temperature in the working process is obtained, which plays a good guiding role in the design of the screw rotor and the improvement of the performance of the compressor

Research on Performance of Variable-Lead Rotor Twin Screw Compressor

Twin-screw compressors are widely used in aerodynamics, refrigeration and other fields. The screw rotors are the core component of the screw compressor and affect the performance of the compressor. This paper focuses on variable-lead rotors. A thermal process simulation model considering leakage is established to calculate the efficiency of the compressor. Different lead change methods are compared by evaluating the contact line, exhaust port and simulation results. The results show that the compressor obtains better performance when the lead decreases rapidly on the discharge side. Furthermore, the effects of the wrap angle and internal volume ratio on variable-lead rotors are studied. The work provides a reference for the design of the screw compressor rotor

Cold-adapted bacteria for bioremediation of crude oil-contaminated soil

BACKGROUND: There are many cold climate terrestrial sites contaminated with petroleum hydrocarbons. Successful bioremediation in these regions relies heavily on suitable microorganisms with biodegrading capability at low temperatures. This work aims at screening cold-adapted bacteria strains and examining their capability of biodegrading petroleum contaminants. RESULTS: Eleven strains of cold-adapted bacteria were isolated from oily sludge taken from a cold environment. Three strains, identified as Chryseobacterium, Bacillus and Pseudomonas, respectively, demonstrated high efficiency in biodegradation of crude oil pollutants based on the growth curves and oil removal rate. The optimal degradation conditions of the three bacteria were 10°C, pH 7 and salinity of 10gL-1 for a crude oil concentration at 1000mgL-1. Under these conditions, the oil removal of the three bacteria after 8 days was 62.3, 61.6 and 60.9%, respectively. The strains were applied in simulated bioremediation tests using artificial contaminated soil containing 5.8-10.6g oil kg-1 soil and achieved 61-78% oil removal after 150 days of bioremediation at 10°C. CONCLUSION: The three cold-adapted bacteria strains are capable of degrading crude oil efficiently at low temperatures and thus are suitable for bioremediation of petroleum contaminated soils in cold environments