模拟酸雨及Al3+共同作用对蚕豆根尖细胞的遗传损伤

以蚕豆为材料,研究了模拟酸雨及酸雨与铝共同作用的细胞遗传学效应.结果表明,根尖细胞有丝分裂指数随Al3 浓度的升高和环境酸度的增强而下降;处理组细胞中出现了多种染色体异常,如染色体粘连、滞后及断裂等.模拟酸雨及其与低浓度Al3 (3mg/L)共同作用时可诱发蚕豆根尖细胞微核,其中pH4.5组微核率高于pH3.5组.模拟酸雨与高浓度的Al3 (10～180mg/L)复合处理可引起根尖细胞固缩,固缩率随Al3 浓度增加和pH降低而增高.研究结果表明,pH4.5和pH3.5的模拟酸雨和Al3 对蚕豆根尖细胞具有遗传损伤作用,其效应与Al3 浓度和环境酸度有关.     

Assessing the bioremediation potential of arsenic tolerant bacterial strains in rice rhizosphere interface

The arsenic tolerant bacterial strains Staphylococcus arlettae(NBRIEAG-6), Staphylococcus sp.(NBRIEAG-8) and Brevibacillus sp.(NBRIEAG-9) were tested for their roles in enhancing plant growth and induction of stress-related enzymes in rice(Oryza sativa L. cv. NDR-359) plants at two different concentrations, 30 and 15 mg/kg of As(V) and As(III), respectively. An experiment was conducted to test the effect of these strains on plant growth promotion and arsenic uptake. We found 30%–40% reduction in total As uptake in bacteria-inoculated plants, with increased plant growth parameters compared to non-inoculated plants. Moreover, the bacteria-inoculated plants showed reduced activity of total glutathione(GSH) and glutathione reductase(GR) compared to their respective controls, which suggests the bacteria-mediated reduction of oxidative stress in plants. Thus, these strains were found to be beneficial in terms of the biochemical and physiological status of the plants under arsenic stress conditions.Furthermore, one-way ANOVA and principal component analysis(PCA) on enzymatic and non-enzymatic assays also revealed clear variations. The results support the distinction between control and treatments in both shoots and roots. Therefore, this study demonstrates the potential of rhizobacteria in alleviating arsenic stress in rice plants.     

An uncertainty based multi-criteria ranking system for open pit mining cut-off grade strategy selection

Cut-off grade strategy (COGS) is a concept that directly influences the financial, technical, economical, and environmental issues in relation to the exploitation of a mineral resource. Despite the simple definition of cut-off grade, the COGS problem is one of the complex and complicated problems in the mine planning process. From the optimization point of view, the COGS with an objective of maximizing the present value of future cash flows is a non-linear and a non-convex problem that even in its deterministic form can be solved using approximate optimization methods. This optimization problem will also be more complex and complicated under uncertainty conditions. This paper proposes an uncertainty based multi-criteria ranking system to investigate the problem of COGS selection considering metal price and geological uncertainties. The proposed system aims at selection of the best COGS among technically feasible alternative COGSs under uncertainty circumstances. Our developed system is based on integrating metal price and geological uncertainties as well as operating flexibility to close the mine early. We incorporate this operating flexibility into the proposed system using a Monte Carlo based real options (RO) valuation model. For this purpose, in addition to the expected value, other risk criteria are considered to rank the alternatives. These risk criteria include abilities of strategies in producing extra profits, minimizing losses, and achieving the predefined goals of the production. In this study, the technically possible COGSs are generated using the Lane comprehensive algorithm. To demonstrate the effectiveness of the proposed system, we utilize data of an Iranian gold mine. Results show that the proposed system outperforms conventional methods in the sense that it shows significantly lower average mis-ranking than the other methods and also selects a strategy with a higher value. The sensitivity analysis of the proposed system relative to the gold price shows that the system is highly dependent on the parameters of the stochastic process used to model the evolution of the metal price. Therefore, special consideration should be given in estimating stochastic process parameters.     

Morphophysiological and Population Adaptations ofAjuga reptansL. at the Northern Boundary of Its Range

The results of comprehensive morphophysiological and population studies on Ajuga reptansL., a species of the nemoral floristic complex, at the northern boundary of its range (in the middle taiga subzone of the Komi Republic) are reviewed. Adaptations at the cell, organism, and biocenotic levels are revealed. The maintenance and survival of the species at the boundary of its range are provided for by its physiological plasticity, resistance to low temperatures, and multiple variants of ontogeny. Prognosis of Ajuga reptansfuture status under conditions of global climate change and expansion of anthropogenically disturbed areas is favorable.     

基于20 L球罐的多相混合物扩散模拟

为更好地探索多相混合物的爆炸特性，以铝粉、乙醚、空气为研究对象，基于20 L球型爆炸罐建立三维计算模型，对气固两相和气液固三相混合物的分散过程进行数值模拟，以分析不同多相混合物分散过程的差异，并为测量多相混合物爆炸下限时的点火延迟时间设定提供参考。监测分析铝粉浓度粒子分布、流场内部湍流动能以及液相体积百分数等的演化过程，讨论混合物分散效果的差异，并确定测量爆炸下限的点火延迟时间。研究结果表明:实验工况下，液相的存在会降低粉尘云团的湍流动能、降低其扩散速度，并使粉尘云内部浓度更均匀。测量多相混合物爆炸下限时，三相混合物的最佳点火延迟时间早于气固两相混合物10~20 ms。     

Post-merger time series analysis: Iron ore mining

In Brazil, mergers and acquisitions are usually analyzed by the antitrust authorities ex post, following a Structure-Conduct-Performance approach close to the US Merger Guidelines. However, this framework was unable to address the complexity posed by a series of acquisitions of four mining companies by the newly privatized national champion Companhia Vale do Rio Doce (known then as CVRD, nowadays as Vale). This article extends a Vector Error Correction model estimated by the Brazilian Ministry of Justice, which eventually came to reinforce the definition of the relevant geographic market and to test for structural breaks in the price series. A formal horizontal merger simulation model was not viable from the available data. Though international prices Granger-caused domestic prices in Brazil, they explain less than a third of the variance. Domestic price hikes in the acquired miners’ series were observed above the export price increase not long after the acquisitions, and a structural break could not be rejected. Since convergence of domestic prices to international levels were not to be punished, remedies eventually applied by the Brazilian Antitrust Tribunal focused on preventing CVRD from abusing dominant position to vertically foreclose competitors in logistics, a key competitive issue for the industry.     

Aqueous and organic extracts of Trigonellafoenum-graecum L. Inhibit the mycelia growth of fungi

Aqueous extracts from various plant parts of fenugreek(3%)(aerial parts:leaves and stems(LS),roots(R),ground seeds(GS)and not ground seeds(NGS))and petroleum ether,ethyl acetate and methanolic fractions of the aerial parts were assayed to determine their antifungal potential against Botrytis cinerea,Fusarium graminearum,Alternaria sp.,Pythium aphanidermatum,and Rhizoctinia solani.All fenugreek plant parts showed antifungal potential and the magnitude of their inhibitory effects was species and plant parts d...     

PRODUCTION AND QUANTIFICATION OF METHYL KETONES IN WILD TOMATO ACCESSIONS

Production of methyl ketones as naturally occurring insecticides from wild tomato accessions is explored in this study. Density of two glandular trichomes (type IV and type VI) on the leaves of six wild tomato accessions of Lycopersicon hirsutum f. glabratum (Mull); three accessions of L. hirsutum f. typicum (Humb & Bonpl.); two accessions of L. pennellii Corr. (D'Arcy); and density of type VI glandular trichomes of the commercial tomato Lycopersicon esculentum cv. Fabulous are reported. Densities of type IV and VI glandular trichomes varied among the accessions tested. Type IV trichomes occurred at much higher densities than type VI. Over all accessions and counting trichome densities on both abaxial and adaxial leaflet surfaces, type IV densities averaged 96,378 trichomes.g^?1 leaflets while type VI densities averaged 67,350 trichomes.g^?1 leaflets. Concentrations of four methyl ketones (2-tridecanone, 2-dodecanone, 2-undecanone, 2-pentadecanone) were determined per unit leaf surface area (mm²) and per g fresh leaflets. Concentrations of total methyl ketones ranged from 81.3 μg. g^?1 fresh leaflets on L. esculentum cv. Fabulous to 5.5 mg. g^?1 on L. hirsutum f. glabratum (PI 134417). Two methyl ketones, 2-undecanone and 2-tridecanone, predominated trichome secretions in five of the L. hirsutum f. glabratum accessions tested (PI 251304, PI 126449, PI 134417, PI 134418, and LA 407).     

烧结烟气选择性催化还原脱硝补热装置的优化

烧结烟气选择性催化还原（SCR）脱硝系统补热烟气与热风掺混的均匀性是保证系统脱硝效率的关键。为提高烟风掺混的均匀性,基于伯努利方程设计了等压热风掺混装置,采用数值模拟的方法对全系统流场分布特性进行了研究。结果表明：等压掺混方式可实现大截面、短距离烟道内烟风的迅速混合;SCR脱硝催化剂入口截面温度和氨氮摩尔比均匀稳定,优化后的温度场温度偏差小于±5 ℃,氨氮摩尔比相对标准偏差小于5%;出口NO_x含量为15~28 mg/Nm³,低于50 mg/Nm³的超低排放技术指标要求。     

基于最小二乘法的灰色 GM（1，1）改进模型在非煤矿山事故预测中的应用

根据灰色理论及其相关理论,通过对GM（1,1）模型中微分方程使用最小二乘法多项式拟合来求解,提出一种改进GM（1,1）模型。将改进模型的预测精度与原始模型进行了比较得出采用二次多项式拟合的改进模型预测精度高于原始模型,因此采用二次多项式拟合GM（1,1）改进模型。并将该改进模型用于我国非煤矿山事故预测中,对2008-2010年我国非煤矿山伤亡事故死亡率进行预测性计算并且与真实数据进行了比对,进一步验证了模型的可行性。