地下室抗水板上浮后施工处理要点

地下室基础有连砂石的一层地下室地板,因其泄水性好,所以设计的抗浮设计偏于保守,基本未采用抗浮锚杆或其他抗浮措施,遇到异常恶劣天气造成该类地下室地板上浮后需采取紧急措施,文章结合工程实际介绍结构加固施工处理措施及要点。

Research of Oxidation Resistance of PVDF Hollow Fiber Membrane Used in Water Treatment

[Objective] The aim was to research the influences of different formulations on oxidation resistance of PVDF hollow fiber membrane.[Method]The immersion precipitation phase inversion method was employed to make casting solution with different formulations into hollow fiber membrane.The membrane was immersed in 1% NaClO solution for testing its performance changes.[Result]The membrane made by materials with bigger molecular weight had better oxidation resistance performance;the surfactant tween-80 could increase water flux,but lead to lower rupture intension;Pore-forming agent PEG400 do better than PVP in the oxidation resistance of membrane.[Conclusion]This study will provide a good idea for the development of the PVDF membrane with high oxidation resistance.

Effect of lamivudinein in BeAg-positive chronic hepatitis B: Discordant effect on HBeAg and HBV DNA according to pretreatment ALT level

AM: To clarify differences in antiviral effect of the drug in patients with different ALT levels, we examined the changes in HBV markers in patients with high or low ALT levels with or without lamivudine treatment. METHODS: Thirty-seven HBeAg-positive patients were studied. Ten patients with ALT levels higher than 200 IU/L (group 1) and 8 patients with ALT below 200 IU/L (group 2) were treated orally with 100 mg/d of lamivudine. As untreated control, 9 patients with ALT above 200 IU/L (group 3) and 10 patients with ALT below 200 IU/L (group 4) were examined. ALT level, HBeAg/HBeAb status, and HBV DNA level were examined monthly for 11.9±0.4 mo. RESULTS: The ALT level normalized in all 10 patients of group 1, 7/8 of group 2, 4/9 of group 3, and 1/10 of group 4 within 6 mo (groups 1 vs2, P= NS; groups 1 vs 3, P= 0.002; groups 1 vs4, P<0.0001). HBV DNA fell below the detection limit in all 10 patients of group 1, 7/8 of group 2, 0/9 of group 3, and 0/10 of group 4 within 6 mo (groups 1 vs 2, P - NS). HBeAg became seronegative in 7/10 patients of group 1, 1/8 of group 2, 3/9 of group 3, and 0/10 of group 4 within 12 mo (groups 1 vs2, P= 0.02; groups 1 vs 3, P= NS). CONCLUSION: Our data suggest that HBeAg-positive patients with higher ALT levels can be considered good candidates for lamivudine therapy, probably because lamivudine accelerates the natural seroconversion of HBeAg, accompanied by HBV DNA loss, in these patients.

STUDIES ON THE PREPARATION OF ZINC-CONTAINING ACTIVATED CARBON FIBERS AND THEIR ANTIBACTERIAL ACTIVITY

Several kinds of activated carbon fibers, using sisal fiber as precursors, were prepared with steam activation or with ZnCl2 activation. Zinc or its compounds were dispersed in them. The antibacterial activities of these activated carbon fibers were determined and compared. The research results showed that these sisal based activated carbon fibers supporting zinc have stronger antibacterial activity against Escherichia coli and S. aureus. The antibacterial activity is related to the precursors, the pyrolysis temperature, and the zinc content. In addition, small quantity of silver supported on zinc-containing ACFs will greatly enhance the antibacterial activity of ACFs.

Design of a modern automatic control system for the activated sludge process in wastewater treatment

The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.

Application of Geopolymer Cement for Groutless Decorative Building Materials

The present study describes the experiments on the application of geopolymer paste for groutless in situ casting or flooring. The paste was synthesized from fly ash and sodium silicate solution and cured at room temperature, 60 and 80℃ for 24 hours. To simulate flooring application, the geopolymer paste was casted on Portland cement cubes which have been fully hydrated for 28 days. Silica fume was added to reduce cracks but at the same time compressive strength decreased. Averaged compressive strength decreased from 53 MPa to 37 MPa for paste cured at 60℃. Curing at higher temperatures produced stronger geopolymer, with compressive strength of 12 MPa, 53 MPa and 67 MPa for geopolymer cured at room temperature, 60℃ and 80℃ respectively, however, higher curing temperature resulted in more cracking when the geopolymer paste was applied on the Portland cement substrate. Averaged hardness values were 65 and 43 Brinnel scale （BHN）, and wear rate, measured using Ogoshi machine, were 0.66 and 1.80 mm3/min for samples cured at 60 and 80℃ respectively. Unless surface hardening was applied, the material is not suitable for flooring but do so for decorative masonry.

Biocompatibility and bone regeneration of PEO/Mg-Al LDH-coated pure Mg:an in vitro and in vivo study

Forming a stable anti-corrosion surface layer on magnesium(Mg)and its alloys has become a major challenge in developing a desirable degradable medical implant in bone.In this study,a porous MgO layer was first formed on Mg by plasma electrolytic oxidation(PEO),and then a Mg-Al layered double hydroxide(LDH)layer was prepared to seal the porous structure of the PEO layer(LDH-2h and LDH-12h)via hydrothermal treatment.The bilayer structure composite coating,which can effectively resist the penetration of surrounding media,is similar to plain Chinese tiles.The in vitro results revealed that compared with other coatings,the LDH-12h composite coating can reduce the release of Mg ions and induce a milder change in pH when immersed in phosphate-buffered saline(PBS).In vitro rat bone marrow stem cell(rBMSC)culture suggested that the LDH-12h composite coating is favorable for cell activity,proliferation and could improve the osteogenic activity of rBMSCs.A subcutaneous implantation test revealed that the as-prepared sample showed enhanced corrosion resistance and histocompatibility in vivo,especially in the LDH-12h group.Moreover,LDH-12h had the lowest rate of degradation and the closest combination with the new bone after being inserted into a rat femur for 12 weeks with no major organ dysfunction.In summary,the asprepared PEO/Mg-Al LDH composite coating is able to improve the corrosion resistance and biocompatibility of Mg and to enhance osteogenic activity in vivo,suggesting its promising prospects for orthopedic applications.