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The sheer lag effect of the steel-concrete composite beam leads to nonuniform distribution of longitudinal stress along the width of flange, thus probably producing disadvantageous transverse cracks. And so, it is necessary to further study the mechanism of shear lag effect of the steel-concrete composite beams with wide flanges, in order to prevent those cracks. The cross-section normal stress differential equation was established for the thin-walled double-room box composite beams, based on the combination of flange micro-unit deformation compatibility condition and equilibrium differential equation; and the analytic stress solution was obtained with the simple-support boundary condition at both ends of the composite beam considered. Finally, the analytic solution was compared with the results of model tests, to prove the accuracy and applicability of the presented method. [ABSTRACT FROM AUTHOR]

The dynamic changes of active components in stems and leaves of Mentha Haplocalycis Herba(mint) at different harvest periods were investigated, and the optimum harvest time of mint was explored. In this study, hesperidin, diosmin, didymin and buddleoside were selected as flavonoids index components of mint, and the QAMS method was established to measure the contents of these flavonoids in mint. The contents of 4 flavonoid glycosides in the mint stems and leaves from three habitats harvested in different time were studied and evaluated comprehensively using statistical analysis and principal component analysis (PCA). The results showed that the contents of 4 components in the leaves are higher than that in the stems despite of habitats and harvest time, and they all exhibited dynamic changes along with the harvest periods within the same habitat. Three harvest periods in mid April, mid September and late October scored higher in comprehensive evaluation in Jiangsu region, the genuine producing area of Mentha Haplocalycis Herba. Combined with the yield and contents of active compounds, the optimum harvest time of mint in Jiangsu region was mid September and late October, which is basically consistent with the traditional harvesting periods., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

Based on the consistent anaerobic status of outer layer of membrane-aerated biofilm reactor (MABR) and internal anaerobic baffled reactor (ABR), MABR and ABR were started up separately. The aerating membrane module was installed into a compartment of anaerobic baffled bioreactor to form the Hybrid MAB-ABR (HMABR). After the installation of membrane module, total COD and VFA concentrations in the HMABR effluent were deceased by 59.5% and 68.1% respectively, with increased nitrogenous pollutant remove efficiency by 83.5%, at influent COD concentration of 1600 mg/L and NH4+ -N concentration of 80 mg/L. When organic loading rate was increased by 50%, the effluent COD concentration was still below the level of 60 mg/L, indicating its good capability of counteracting influent organic loading fluctuation. Due to the decreased COD concentration and increased nitrate concentration in the third compartment after installing the membrane module, the biogas volume and methane contents in the third compartment were decreased, resulting in the steady and excellent effluent quality. In this hybrid process, the improved simultaneous removal of carbon and nitrogen for high-strength nitrogenous organic pollutants was realized in a single reactor.

A membrane bioreactor (MBR) was developed successfully to carry out partial nitrification process. Temperature, and dissolved oxygen (DO) were investigated as the factors which may affect the results. It has been proved that the optimal operational parameters were at 35 degrees C, ammonia loading 0.45 kg x (m3 x d)(-1) and < 0.5 mg/L, respectively, with the effluent NO3(-) -N concentration below 20 mg x L(-1) and rho(NO2(-) -N)/rho(NH4(+) -N) ratio being close to 1.0. It is not observed severe membrane fouling during all the experiment. Fluorescence in situ hybridization analysis indicated that aerobic ammonium oxidizers were the dominant population, and nitrite-oxidizing bacteria were inhibited. The microbiological community analysis further provided the necessary biological information for the realization of partial nitrification.

A carbon membrane-aerated biofilm reactor was developed to treat municipal wastewater, in which the carbon and nitrogen were removed simultaneously. The results showed that COD removal, NH4+-N removal and TN removal efficiency could reach 82.5%, 95.1% and 84.2%, respectively, under the conditions of intra-membrane pressure of 13.6 kPa, HRT of 14 h, influent COD and NH4+-N concentrations of 338 mg/L and 75 mg/L. However, in the last period during the operation of the reactor, the TN removal efficiency dramatically decreased because of the excessive growth of biomass on the nonwoven fiber, which also had serious negative effect on nitrification course. The microbiological community and spatial profiles were observed by fluorescence in situ hybridization and scanning electron microscopy. The anaerobic and anoxic bacteria were mainly located in the outer anaerobic region of the biofilm, while the aerobic ammonium oxidizing bacteria were mainly located in the inner aerobic region of the biofilm. The co-existing and coupling effect of aerobic nitrifying bacteria and anaerobic denitrifying bacteria provided the large biological potential for the simultaneous nitrification and denitrification in the carbon membrane-aerated biofilm reactor.

The effect of alkaline thermal hydrolysis method on excess sludge and its characteristic parameters(such as soluble chemical oxygen demand, volatile fatty acids, ammonia-nitrogen, pH value, sludge concentration, etc.) were investigated. The results show that the addition of alkali can reduce the resistance of the sludge cells to high temperature and enhance the release and the hydrolysis of organic materials from the sludge cells with the increase of temperature, pH value and reaction time. The concentration of SCOD reached 17,950 mg/L and SCOD/TCOD was 0.65 on the conditions of pH 13, 170 degrees C and 75 min. The maximal dissolving rate of suspended solids (SS) was 67% and 72% for volatile suspended solids (VSS) at pH 13 with 60 min. The concentration of SCOD after alkaline thermal hydrolysis treatment increased with the increase of sludge concentration, in which the nice linear relation was reached and the correlation coefficient (R2) was above 0.97. The increasing rate of the SCOD was improving with the increase of the pH value and the SCOD of unit sludge reached 672 mg/g at pH 13. The effect of three factors on the SCOD was investigated through orthogonal experiment at the temperature of 170 degrees C, the importance was sludge concentration,pH value and reaction time in turn.

New type hybrid biological reactor was developed by initiating the carbon membrane aeration in ABR which was augmented with carbon aerated membranes to improve wastewater treatment by removing COD, NH4(+) -N and TN. The results showed that on the conditions of intra-membrane pressure of 0.025 MPa, HRT 24 h, influent COD 2000 mg/L, NH4(+) -N 50 mg/L, simultaneous nitrification and denitrification was happened, and COD and NH4(+) -N decreased from 156 mg/L, 36 mg/L to 45 mg/L, 6 mg/L respectively after the membrane aeration with biofilm was initiated in the third compartment of ABR.TN removal reached 87.66%, and VFA and biogas was decreased by 77.12% and 30%, respectively.

A carbon membrane-aerated biofilm reactor was developed to treat nitrogenous inorganic wastewater. Influent NH; -N concentrations and HRT were changed to investigate nitrification performance of reactor,oxygen utilization and NH4+ -N's removal loading. Biofilm's surface characteristics and dominant bacteria of nitrifier were analyzed. The results show that under the conditions of intra-membrane pressure of 0.017 MPa, influent NH4+ -N of 50 mg/L and HRT of 8 h NH4+ -N removal efficiency reaches 96% and effluent average nitrite is 17 mg/L, which benefits short-cut nitrification to a certain extent. The bacteria within biofilm consume all oxygen supplied through carbon membrane. The maximum specific removal rate of NH4+ -N is 9.7 g/(m2 x d), which is limited by the amount of bacteria grown onto carbon membrane's surface. Fluorescent in situ hybridization analysis indicates that within the biofilm Nitrosomonas and Nitrosospira are main ammonia-oxidizing bacteria and occupy about 19% and 21% of the total bacteria number, respectively. The Nitrobacter are not observed and Nitrospira are dominant nitrite-oxidizing bacteria, the fraction of which is 20% of total bacteria.

A carbon membrane-aerated biofilm reactor was developed to treat municipal wastewater. Tests were conducted to investigate oxygen transfer ability of carbon membrane, the bacteria adhesion and reactor's set-up performance. The optimum parameters were determined in terms of intra-membrane pressure, COD and nitrogen ratio and hydraulic retention time (HRT). The results showed that compared with that of other hollow fibres, bacterial suspended exhibited a high degree of adhesion onto carbon membrane and that oxygen transfer coefficient of carbon membrane was 0.36 m/h, so that it was feasible to serve as both biofilm carrier and aerator. NH4(+) -N removal, denitrification and COD removal efficiency could reach 95%, 92% and 88%, respectively, under the conditions of intra-membrane pressure of 0.025 MPa, carbon nitrogen ratio of 5 and HRT of 8 h, and effluent quality could be up to A standard in the national discharge standard of pollutants for municipal wastewater treatment plant (GB 18918-2002) . Furthermore, the system displayed better resistance to shock loads.