Differential expression of rice oxalate oxidase genes (OsOxO1-4) in rice leaves (Oryza sativa L.) in response to biotic stress was assayed using RT-PCR. OsOxO4 was induced transiently at 12 h in plants inoculated with the pathogens of bacterial blight and that of the wounding control. Inoculation with the rice blast pathogen induced OsOxO2 expression compared to the mock spray control. Overexpressing OsOxO1 or OsOxO4 in rice resulted in elevated transcript levels of the respective transgene as well as OsOxO3 in leaves compared to that in untransformed wild type (WT). In a line of RNA-i transgenic rice plants (i-12), expression of all four OsOxO genes except that of OsOxO2 was severely inhibited. Oxalate oxidase (OxO, EC 1.2.3.4) activity in plants overexpressing OsOxO1 or OsOxO4 was substantially higher than that in WT and the RNA-i lines. It was found that transgenic rice plants with substantially higher OxO activity were not more resistant to rice blast and bacterial blight than WT. In contrast, some RNA-i lines with less OxO activity seemed to be more resistant to rice blast while some overexpressing lines were more susceptible to rice blast than WT. Therefore, OxO might not be a disease resistance factor in rice.
A U-shaped metal seal in coiled tubing wellhead hanging device was designed, the metal seal material is brass(H59, H70). The contact stress of sealing interface was analyzed by finite element method analysis, the U-shaped seal has elastic-plastic deformation after excitation force applied, and the plastic deformation region concentrated in contact areas. The influence of U-shaped metal seal initial clearance on sealing effect was presented, the reasonable initial clearance ratio region are 0.8 to 0.9. Excitation forces in different excitation angles were calculated, the reasonable excitation angle region are 15° to 20°. Metal seal overcomes the defects of conventional rubber elastomers, that ensure the safety of wellhead hanging device construction, also improve the service life.
The fractional volume of the reservoir sand shall be taken to the ground when the crude oil is brought up from the ground. With the deepening of the oil extraction the sand content of oil recovery is increasing. Although many measures have been used such as prevent sand, block sand and so on, the viscosity of heavy oil is big and the fractional of sand is carried into the crude oil gathering system inevitably, causing a series of problems at ground equipment, having a serious impact on the normal production and gathering of crude oil. The larger size of sand can be removed by the sedimentation and the smaller sand can be removed by hydrocyclone devices. Hydrocyclone is a separation plant used to separate non-uniform phase mixtures. It can be used to complete the liquid clarification and to wash particles, liquid degassing and grit removal, grading and classification of solid particles and the separation of two non-miscible liquids and others. Hydrocyclone separation technique is simple and convenient operation, high separation efficiency, no rotating units, small size and easy to realize automatic control. On the offshore platform,if the sand mixed with oil is discharged into sea unsatisfactory the standard, it will pollute the sea. It will cause a serious of marine pollution; this is a problem that should be solved quickly. This paper discusses the requirements for the design of the hydrocyclone desander equipment with compact structure, applicable to offshore drilling platforms,and carrying out CFD simulation, the results showing that the particle size of 75 of sand, grit removal efficiency above 90%.
Reliability of eccentric wear casing was studied by Monte-Carlo and finite element method. In different internal pressures, calculated reliability of P110 steel grade 9 5/8 inches casing with wear depth less than 0.5 times wall thickness. The influence of different cement ring circumferential missing amount and stratum pressures on wear casing reliability were presented. The results provide basis for casing safety evaluation and reasonable replacement.
Strength of residual wall thickness reliability was studied by Monte-Carlo and finite element method, based on 40in X70 steel and 48in X80 steel which were often used in oil and gas transport pipeline. Pipe with defects in different residual wall thinkness, calculated the critical residual value of wall thickness, and analysed the defect depth and width of influence on pipe reliability. The results provide basis for pipeline safety evaluation and reasonable replacement.
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