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According to the development need of deep pump extraction in oil fields, inserted load reducer is developed. The load reducer is improved in its structure for sucker rod pumping, and inserted multi-stage sealing construction is used to improveing sealing ability. Drainage hole is added to the big pump barrel in order to create the oil drainage passageway between flowout hole and drainage hole, and avoid contaminate in productive process. The load reducer can deepen pump depth and improve oil production by means of reducing jack load of pumping well. It can improve liquid rate of deep reservoir and low permeability producers, reduce cost, and reduce pumping energy consumption. Field application shows that the jack load of pumping well is reduced obviously, realize the goal of energy saving and production enhancing. [ABSTRACT FROM AUTHOR]

In order to obtain virus-like particles (VLPs) for prevention of bovine viral diarrhea virus 1 (BVDV-1), the C-E rns -E1-E2 region was cloned into a pFastBacDaul vector for generating the recombinant Bacmid-BVDV-1 in DH10Bac Escherichia coli . The recombinant baculovirus Baculo-BVDV-1 was produced by transfecting the Sf9 cells with Bacmid-BVDV-1. The expressed protein and the assembled VLPs were determined by immunofluorescence, Western blotting and electron microscopy. Guinea pigs were immunized with inactivated VLPs coupled with the Montanide ISA-201 adjuvant. The immunogenicity of VLPs was evaluated by monitoring the humoral immune response with neutralizing antibody titer determination, as well as by analyzing the cell-mediated immune response with lymphocyte proliferation assay. The protective efficacy of VLPs was evaluated by challenging with 10 6 TCID 50 virulent BVDV-1 strain AV69. The results showed that the recombinant Baculo-BVDV-1 efficiently expressed BVDV structural protein and form VLPs in infected Sf9 cells. The immunization of guinea pigs with VLPs resulted in a high titer (1:144) of neutralizing antibody, indicating an activated cellular immunity. Significantly lower viral RNA in the blood of the post-challenged immunized guinea pigs was observed. The successful preparation of BVDV VLPs with insect cell expression system and the observation of the associated immunogenicity may facilitate further development of a VLPs-based vaccine against BVD.

Objective: To analyze the etiology and risk factors of central venous catheter (CVCs) infections, and to explore the prophylaxis and treatment for catheter-related infections., Methods: A retrospective study was conducted. The patients with CVCs admitted to intensive care unit (ICU) of Qianfoshan Hospital Affiliated to Shandong University from January 2000 to December 2016 were enrolled. The gender, age, catheter data and microorganism culture results of all patients were collected. The infection rate and the incidences of CVCs infection per 1 000 catheter days were calculated. The risk factors of CVCs infection were analyzed by Logistic regression., Results: 1 160 patients were enrolled in 17 years [male 915, female 245, age 7-98 years, mean (71.8±17.5) years]. The incidences of CVCs infection per 1 000 catheter days were descended every 3 years (cases/1 000 days: 21.87, 24.50, 19.95, 12.64, 16.34, 12.40, χ 2 = 38.851, P = 0.000). Of the 1 160 patients, 375 were positive for catheter culture, and 397 strains were cultured, among which 173 strains (43.58%) were Gram negative (G - ), 130 strains (32.74%) of Gram positive (G + ), and 94 strains of fungi (23.68%). Non-fermenting bacteria (Pseudomonas aeruginosa 11.59%, Acinetobacter baumannii 8.82%) was predominant in the G - bacteria, followed by Enterobacteria (Klebsiella pneumoniae 8.06%, Escherichia coli 2.02%); Staphylococcus spp. (Staphylococcus epidermidis 11.84%, Staphylococcus aureus 5.29%) was the main species of G + bacteria; the main fungi were Candida tropicalis (9.07%) and Candida albicans (5.79%). The catheter infection rate of internal jugular vein, femoral vein and subclavian vein were 36.07% (22/61), 35.52% (119/335), 30.63% (234/764) respectively (χ 2 =2.275, P = 0.099), the incidence of catheter infection of three vein insertion sites per 1 000 catheter days were 18.00, 17.71, 17.08 cases/1 000 days respectively (χ 2 = 0.034, P = 0.714). The mean placement time of infected CVCs in situ was longer than that of non-infected CVCs (days: 20.80±11.68 vs. 17.64±10.77, t = 4.417, P = 0.000).The positive rate was lowest during 1-7 days of indwelling time (19.87%, 30/151). The infection rate was increased with long indwelling time. The positive rate was 44.44% (68/153) as indwelling time was over 30 days. The infection rate was significantly positively related to indwelling time (χ 2 = 22.849, P = 0.000). Multiple Logistic regression analysis showed that the infection risk of femoral vein catheter was increased [odds ratio (OR) = 1.362, 95% confidence interval (95%CI) = 1.030-1.801, P = 0.030] as compared with that of subclavian vein catheter; the infection risk was increased with long indwelling time (OR = 1.306, 95%CI = 1.177-1.480, P = 0.000)., Conclusions: G - are the major pathogens of CVCs infection. Femoral vein catheter and long indwelling time are the risk factors of CVCs infection.