C70自密实钢管混凝土材料配制技术

提高核心混凝土的强度是提高钢管混凝土承载力的重要途径。配制C70高强自密实钢管混凝土材料满足钢管混凝土的施工条件和性能要求:早期强度高,3 d抗压强度达到28 d的86.3%;工作性能优良,抗分离性能好,垂直浇筑4 m高钢管混凝土柱,各组分均匀分布;弹性模量不低于振实混凝土,为4.6×104 MPa;能产生足够的膨胀,360 d的自由膨胀率为6.9×10-4。

高流动混凝土基本性能及施土性能

高流动混凝土是指用于混凝土结构中 ,具有高流变性和抗分离性 ,不需振捣进行自充填的混凝土。高流动混凝土是以提高混凝土结构物的耐久性、可靠性和适应 2 1世纪新的施工技术为目的而提出的 ,是一种新概念混凝土。本文从基本性能、施工技术。

免振混凝土在宁夏固海扩灌工程中的应用

利用化学外加剂的分散作用代替机械振捣施工 ,使混凝土充分填充构筑物内部并达到自密实状 态 ,从而解决了井柱施工中振捣施工极不方便的困难。

Isolation and Identification of Cardenolide Compounds of Gomphocarpus sinaicus and Their Fungicidal Activity Against Soil Borne and Post Harvest Fungi

This study was undertaken to explore new antifungal compounds from the methanolic extract of G. sinaicus. Two cardenolide compounds were isolated and identified by GC-MS as cardenolide glycoside, 15-hydroxy-3,4,5,6-dehydrocalotropin and cardenolide genin, 3,4,5,6-dehydrocalotropagenin. The antifungal activity of these compounds was assessed. Results revealed that both compounds showed pronounced fungicidal activity against both soil borne fungi, R. solani, F. oxysporium, and postharvest fungi, R. stolonifer, P. digtatum, compared to the standard fungicides, flutolanil and copper oxychloride, respectively. The ECs0 values of the cardenolide genin were 0.703, 13.63 and 4.22, 8.403 lag/mL forR. solani, F. oxysporium andR. stolonifer, P. digtatum respectively. On the other hand, the ECs0 values of the standard fungicide, flutolanil, were 9.49 and 61.22 ~tg/mL against R. solani and F. oxysporium. While the ECso values of copper oxychloride were 279.94 and 187.13 p.g/mL against R. stolonifer and P. digtatum, respectively. The results showed that cellulase, PME, PPO of the tested fungi was more sensitive than to cardenolide genin. The strong antifungal activity of cardenolide genin reported in this study indicated that has a potential to be used as fungicides.

Structures and Antiviral Activities of Butyrolactone Derivatives Isolated from Aspergillus terreus MXH-23

A new butyrolactone derivative,namely butyrolactone Ⅷ （1）,and six known butyrolactones （2-7） were separated from the ethyl acetate （EtOAc） extract of the fermentation broth of a fungus,Aspergillus terreus MXH-23.The chemical structures of these metabolites were identified by analyzing their nuclear magnetic resonance （NMR） and mass spectrometry （MS）.Known butyrolactone derivatives contain an α,β-unsaturated γ-lactone ring with α-hydroxyl and y-benzyl,and butyrolactone Ⅷ （1） was the first butyrolactones contains α-benzyl and γ-hydroxyl on α,β-unsaturated lactone ring.All of the butyrolactone derivatives were tested for their anti-influenza （H 1N 1） effects.Derivatives 4 and 7 showed moderate antiviral activities while the newly-identified,derivative 1,did not.

Isolation and Antifungal Evaluation of Rumex cyprius Murb Extracts

Ethanolic extract of dried Rumex cyprius Murb （polygonaceae） was tested against four pathogenic fungi： three dermatophytes, Microsporum canis, Trichophyton mentagrophytes and T. rubrum, and the causative agent of chalkbrood disease of bees, Ascophaera apis. The extract showed considerable activity against all these fungi. One of the main constituents ofRumex cyprius was isolated and tested for its antimycotic activity. It showed a significant activity against the test fungi and was identified as 1,3,8-trihydroxy-6-methylanthracene-9,10-dione based on its IR, UV-V and 1^H NMR spectra.

Changes of Resistance During Polyelectrolyte-enhanced Stirred Batch Ultrafiltration

The permeation flux or the resistance in the ultrafiltration process is mainly limited by osmotic pressure, and it may originate from various kinds of polymer interactions. However, the real origin of permeation resistance hasn＇t been clarified yet in the light of polymer solution nature. The removal of nitrate contamination by polyelectrolytes was carried out with stirred batch ultrafiltration. The polyelectrolyte concentrations both in permeate and retentate were analyzed with total organic carbon analyzer and permeate mass was acquired by electronic balance connected with computer. The total resistance was calculated and interpreted based on the osmotic pressures in three concentration regimes. In the dilute region, the resistance was proportional to polymer concentration; in the semidilute region, the resistance depended on polymer concentration in the parabolic relationship; in the highly concentrated solution regime, the osmotic pressure factor （OPF） would dominate the total resistance; and the deviation from OPF control could come from the electrostatic repulsion between the tightly compacted and charged polyelectrolyte particles at extremely concentrated solution regime. It was first found that dilute and semidilute concentration regions can be easily detected by plotting the leg-log curves of the polymer concentration versus the ratio of the total resistance to polymer concentration. The new concept OPF was defined and did work well at highly concentrated regime.

Prevalence of Antibiotic Resistant Bacteria on Tomato Surfaces and Effectiveness of Disinfectants in Reducing the Microbial Load

This study was conducted to isolate and identify antibiotic resistant bacteria in fresh tomato sold in three different local markets of Dhaka city. On an average 〉 5.0 log CFU/g of natural microbial populations and coliform bacteria was present in the samples. Prevalence of Salmonella spp., E. coli, Listeria spp., and Yersinia spp., were recorded through cultivation dependent assay of tomato samples of different markets. Almost all of the isolates were uniformly resistant to rifampicin, erythromycin, clindamycin and oxacillin （100%）, vancomycin （93%）, amoxicillin （87%）, whereas 60% of the isolates were found to be resistant to ampicillin and cephalexin. Antibiotic sensitivity test of the presumptive E. coli and Salmonella spp. and corresponding plasmid profiling indicated a correlation of plasmid mediated multidrug resistance （MDR） of these environmental bacteria. Washing with sanitizing agents such as acidified sodium chlorite （ASC） and 200 ppm chlorinated water was able to reduce _〈 2.0 log CFU/g of natural microflora and coliform bacteria. In contrast, ASC was able to reduce 〈 2.0 log CFU/g of other food borne pathogens and, chlorinated water was able to reduce up to undetectable level. Therefore, washing of tomato with 200 ppm chlorinated water could be useful in reducing the pathogen populations on tomatoes.

Occurrence and Antibiotic Susceptibility Profile of Streptococcus spp. Isolated from Ewe＇s Milk

The purpose of this study was to determine the occurrence and antimicrobial resistance of Streptococcus spp. isolated from fresh ewe＇s milk and consequently to draw conclusions concerning the health condition of the animal flocks and the current trends of antibiotic use in small ruminants. A total of 77 mountainous sheepfolds were investigated representing 10% of all transhumant sheep and goats flocks in the area. Duplicate milk samples were collected from January to February transferred to the laboratory and analyzed for the presence of Streptococcus spp. by using the serial dilution method and plating on the surface of Slanetz and Bartley agar. The isolates were tested against nine antimicrobial agents with the Kirby-Bauer disk diffusion method. The results showed that Streptococcus spp. occurred in 84.4% of the samples and in counts ranged between 1.8 log CFU/mL and 4.6 log CFU/mL. Concerning susceptibility, only 1.3% of the isolates were resistant to all antimicrobials while 27.3% were fully susceptible. Resistance to cefepime was the most common （93.1%） observation followed by resistance to ampicillin （82.1%）, ciprofloxacine （58.3%） and meropenem （51.9%）. The isolates were vancomycin susceptible at a rate of 83.6%. Multidrug resistance to at least three antibiotics was observed to be 22.1% of Streptococcus spp.. Given the prevalence of Streptococcus spp. and the elevated resistance of isolates to various antibiotics it is concluded that further examinations and even interventions are required in order to pertain the appropriate animal health and milk quality.

Endophytic Fungi Isolated from Mangrove （Rhyzopora mucronata） and Its Antibacterial Activity on Staphylococcus aureus and Escherichia coli

Disc diffusion method was used to investigate the antibacterial activity of methanol extract of five endophytic fungi isolated from mangrove （Rhizopora mucronata） on Staphylococcus aureus ATCC 9144 and Escherichia coli ATCC 8739, Fungi were isolated from leaf, stem and root of R. mucronata. Potato dextrose agar and potato dextrose broth were used for fungi purification and fermentation. Fungal metabolites were extracted with methanol （1 ： 1 v/v） for 24 h before vacuum evaporated to yield the crude extracts. Antimicrobial activity test was done according to the Kirby-Bauer test. The inhibition zone around each disc was considered to measure antibacterial activity of endophytic fungi. Only three endophytic fungi showed inhibition activity on S. aureus ATCC 9144 and two endophytic fungi showed inhibition on E. coil ATCC 8739. The results suggested that the extracts have a high potential for enteric diseases treatment caused by foodbome pathogen.

水下混凝土水中不分离剂应用技术

本文介绍水中不分离剂的主要成分及其配制成的水中不分离混凝土的主要性能,以及此种新型水下混凝土的施工要求及其工程应用情况。

Non-alkaloid constituents of Vinca major

The present study was designed to investigate the non-alkaloid compounds from the leaves and stems of Vinca major cultivated in Yunnan Province, China. The compounds were isolated using chromatographic techniques. The structures were elucidated by 1D- and 2D-NMR spectroscopic methods in combination with UV, IR, and MS analyses. The 1, 1-diphenyl-2-picrylhydrazyl （DPPH）-scavenging activity of Compounds 1-7 were evaluated. One new iridoid glycoside （compound 1）, together with 11 known compounds, were isolated from Vinca major. Compounds 1, 5, and 6 showed moderate DPPH-scavenging activity, with IC50 values being 70.6, 32.8, and 62.2μmaol·L 1, respectively. In conclusion, compound 1 is a newly identified iridoid glycoside with moderate antioxidant activity.