Structure-activity relationship of novel acridone derivatives as antiproliferative agents.

Unlike other DNA topoisomerase II (topo II) inhibitors, our recently identified acridone derivative E17 exerted strong cytotoxic activity by inhibiting topo II without causing topo II degradation and DNA damage, which promoted us to explore more analogues of E17 by expanding its chemical diversification and enrich the structure-activity relationship (SAR) outcomes of acridone-oriented chemotypes. To achieve this goal, 42 novel acridone derivatives were synthesized and evaluated for their antiproliferative efficacies. SAR investigations revealed that orientation and spatial topology of R3 substituents make greater contributions to the bioactivity, exemplified by compounds E24, E25 and E27, which has provided valuable information for guiding further development of acridone derivatives as promising drug candidates.

E17 exerts anti-tumor activity through inhibiting topo II-mediated chromosomes condensation in CRC cells.

Topo II inhibitors, e.g. etoposide, doxorubicin and mitoxantrone, etc., which exert their functions by trapping the covalent 'topo II-DNA cleavable complex' via intercalation into DNA base pairs, leading to DNA damage and degradation of topo II, and inducing decline of cell sensitivity and corresponding multidrug resistance (MDR). E17 is a recently identified topo II inhibitor in our lab which has validated to possess a strong topo II inhibitory activity on cell viability, colony formation, and cell migration. Especially, E17 can trigger G2/M cell cycle arrest through inhibiting chromosome condensation without causing obvious DNA damage in colorectal cancer (CRC) HCT116 cell. E17 can also induce the accumulation of topo II-DNA complex without leading to degradation of topo II, which was different from topo II inhibitors VP16 or ICRF-187, suggesting E17 might be a potential lead for further development by serving as a strong topo II inhibitor.

[Research of potassium flow and circulation based on substance flow analysis].

Mass of potassium is consumed in the process of crop production, which is the dominating section of potassium flow and circulation in China. However, the degree of self-sufficiency is relatively low due to the deficient domestic resource of potassium. This study analyzed the key links of potassium issues in crop production and consumptive use in 2009 based on substance flow analysis. The results indicated that the farmland nutrient balance of input/output couldn't make even, with a heavy deficit of 50.4 kg x hm(-2) at the national level. Meanwhile, about 2.31 million ton of potash fertilizer was washed away into the hydrologic cycle, which accounts for 40.97% of chemical fertilizer applied in the whole year. Domestic wastewater in urban and rural areas was identified as another primary source for the transformation of potassium from terrestrial ecosystem to water environment system, annually contributing 671 and 547 thousand tons, which takes up 19.00% and 15.50%, respectively. And the amount of potassium in effluent of wastewater treatment plants was 505 thousand tons per year, accounting for 75.25% of the total emission in urban areas.

Retrofitting conventional primary clarifiers to activated primary clarifiers to enhance nutrient removal and energy conservation in WWTPs in Beijing, China.

Biological nutrient removal requires sufficient carbon source. Meanwhile, the removal of organic matter in wastewater requires energy consumption in the aeration tank. Carbon source for nutrient removal in most wastewater treatment plants with conventional primary clarifier (CPC) is generally insufficient in China. In order to increase carbon source and to save energy, a part of the CPC may be retrofitted as an activated primary clarifier (APC). In this paper, a pilot scale experiment was conducted to examine the performance of primary sludge fermentation and its effect on nitrogen and phosphorus removal. Results show that the primary sludge fermentation in APC has produced a similar VFA/TP ratio but a higher BOD5/TN ratio compared with those in the CPC effluent, and the TN concentrations in the secondary effluent are at 8.0, 10.8, and 17.4 mg/L, while TP is at 0.45, 1.10, and 2.28 mg/L when the pilot test system was fed with (1) the APC effluent, (2) 50% from the APC effluent and 50% from the CPC effluent, and (3) the CPC effluent, respectively. Results also indicate that the BOD5/TN ratio is a more sensitive factor than the VFA/TP ratio for nutrient removal and energy conservation for the APC fermentation.

[Risk assessment of river water quality under accidental pollution based on Bayesian networks].

Risk assessment for accidental pollution plays an important role in river water quality management. Bayesian networks can be applied to represent the relationship between pollution sources and river water quality intuitively. A time sequential Monte Carlo algorithm, integrated with pollution sources model, water quality model and Bayesian reasoning, is developed to quantify river water quality risk under the collective influence of multiple pollution sources. A case study shows that multiple pollution sources have obvious effect on water quality risk of the receiving water body, which means that integrated management should be developed for multiple risk sources. The model could also support the decision-making process of river basin management through identification of critical pollution sources.

[Micro-simulation of firms' heterogeneity on pollution intensity and regional characteristics].

In the same industrial sector, heterogeneity of pollution intensity exists among firms. There are some errors if using sector's average pollution intensity, which are calculated by limited number of firms in environmental statistic database to represent the sector's regional economic-environmental status. Based on the production function which includes environmental depletion as input, a micro-simulation model on firms' operational decision making is proposed. Then the heterogeneity of firms' pollution intensity can be mechanically described. Taking the mechanical manufacturing sector in Deyang city, 2005 as the case, the model's parameters were estimated. And the actual COD emission intensities of environmental statistic firms can be properly matched by the simulation. The model's results also show that the regional average COD emission intensity calculated by the environmental statistic firms (0.002 6 t per 10 000 yuan fixed asset, 0.001 5 t per 10 000 yuan production value) is lower than the regional average intensity calculated by all the firms in the region (0.003 0 t per 10 000 yuan fixed asset, 0.002 3 t per 10 000 yuan production value). The difference among average intensities in the six counties is significant as well. These regional characteristics of pollution intensity attribute to the sector's inner-structure (firms' scale distribution, technology distribution) and its spatial deviation.

[Development and application of a multi-species water quality model for water distribution systems with EPANET-MSX].

A conceptual multi-species water quality model for water distribution systems was developed on the basis of the toolkit of the EPANET-MSX software. The model divided the pipe segment into four compartments including pipe wall, biofilm, boundary layer and bulk liquid. The involved processes were substrate utilization and microbial growth, decay and inactivation of microorganisms, mass transfer of soluble components through the boundary layer, adsorption and desorption of particular components between bulk liquid and biofilm, oxidation and halogenation of organic matter by residual chlorine, and chlorine consumption by pipe wall. The fifteen simulated variables included the seven common variables both in the biofilm and in the bulk liquid, i.e. soluble organic matter, particular organic matter, ammonia nitrogen, residual chlorine, heterotrophic bacteria, autotrophic bacteria and inert solids, as well as biofilm thickness on the pipe wall. The model was validated against the data from a series of pilot experiments, and the simulation accuracy for residual chlorine and turbidity were 0.1 mg/L and 0.3 NTU respectively. A case study showed that the model could reasonably reflect the dynamic variation of residual chlorine and turbidity in the studied water distribution system, while Monte Carlo simulation, taking into account both the variability of finished water from the waterworks and the uncertainties of model parameters, could be performed to assess the violation risk of water quality in the water distribution system.

[Inventory of regional surface nutrient balance and policy recommendations in China].

By applying OECD surface soil nitrogen balance methodology, the framework, methodology and database for nutrient balance budget in China are established to evaluate the impact of nutrient balance on agricultural production and water environment. Results show that nitrogen and phosphorus surplus in China are 640 x 10(4) t and 98 x 10(4) t respectively, and nitrogen and phosphorus surplus intensity in China are 16.56 kg/hm2 and 2.53 kg/hm2 respectively. Because of striking spatial difference of nutrient balance across the country, China is seeing a dual-challenge of nutrient surplus management as well as nutrient deficit management. Chemical fertilizer and livestock manure are best targets to perform nutrient surplus management due to their marked contributions to nutrient input. However, it is not cost-effective to implement a uniform management for all regions since nutrient input structures of them vary considerably.

[Nitrogen flow in farming-feeding system and its environmental impact in China].

By applying nitrogen flow model for farming-feeding system (NFM-FFS) which integrates soil full nitrogen balance model with inventory analysis for agricultural pollution, nitrogen flow in China farming-feeding systems and its environmental impact are analyzed. In 2003, although surface nitrogen surpluses, nitrogen deficit in agricultural soil system in China is estimated to be 623.9 x 10(4) t, and 13.7 kg/hm2 averagely, which implies that soils in China farming-feeding systems are at the risk of nitrogen content decline and potential soil degradation as a whole. With a intense nutrient input in arable land and no extra fertilizer input in grassland in China, there is a nitrogen surplus of 1761.9 x 10(4) t, averagely 142.8 kg/hm2, while grassland has a deficit of 2,385.7 x 10(4) t, averagely 90.7 kg/hm2. As a result, existing negative impact of cropping activities on water environment as well as grassland degradation may be effectively abated by balancing nitrogen input between arable land and grassland. Total nitrogen loss from China farming-feeding system is 2,266 x 10(4) t, including 495.8 x 10(4) t exported into surface water by drainage and surface runoff, and 102.4 x 10(4) t into groundwater by leaching. Lost nitrogen is to be deposited in rivers, lakes and marine system, and is less likely to return to farming-feeding system. Fertilizer should be the priority of rural pollution control and management because of its dominant contribution to nitrogen exported into water environment from farming-feeding system.

[Substance flow analysis on phosphorus cycle in Dianchi basin, China].

Investigation of physical profiles of nutrients within socio-economic systems is one of the key approaches to cure eutrophication. Applying a substance flow analysis (SFA) method for the case of Dianchi basin located in southwest of China, we established a regional static SFA model (PHOSFAD) in 2000 via balancing societal phosphorus flows. Aggregate characteristics of the overall phosphorus throughput, and physical efficiencies in relation to phosphorus uses of production and consumption sectors, including mining, processing, farming, livestock husbandry and household consumption, were subsequently identified. The methodology and results of this study illustrate applicability and value for rational decision-making aiming to curb eutrophication of Dianchi Lake.

[Developing a statistical conceptual model for pre-chlorination process in waterworks].

Aiming at a method of risk analysis for drinking water treatment, a statistical conceptual model was developed to simulate the pre-chlorination process in waterworks, which involved the reactions among chlorine residuals, ammonia nitrogen, bromide and organic matter. The model was calibrated and verified with field data from a typical waterworks. The model could well predict the probability distribution of the concentration of permanganate index, ammonia nitrogen, chloroform, bromodichloromethane, chlorodibromomethane and bromoform in the pre-chlorination process.

Assessment of water pollution control strategies: a case study for the Dianchi Lake.

Lake eutrophication has increasingly become a major environmental issue in China. Although significant efforts have been made towards its resolution in the last decade, most of the implemented control strategies are fragmented, and the formation of policy lacks of sound scientific basis and long-term objectives. Taking the well-known Dianchi Lake as a case study, this paper presented a comprehensive assessment for the effectiveness of various eutrophication control strategies. It is expected that the concluding lessons would have a major implication to future eutrophication control.