Oxidation of Chlorophenols in Aqueous Solution by Excess Potassium Permanganate

A simple spectrophotometric method was developed to quantify chlorophenol (CP) concentrations after reaction with potassium permanganate and quenching with sodium sulfite. Other quenching agents (peroxide, sodium thiosulfate and hydroxylamine hydrochloride) were found to create absorbance in the spectral range required for CP quantification. Analysis at pH 12 gave greater absorption and sensitivity for the method compared with pH 5.6. The calibration curves of the proposed methods were linear in the concentration ranges 0.0061–0.61 and 0.0078–0.78 mM with detection limit of 0.0006 and 0.0008 mM for dichlorophenols and monochlorophenols, respectively. The oxidation kinetics of five chlorophenols in aqueous solution with excess potassium permanganate were evaluated using the analytical method. The pseudo-first-order reaction rates were found to be relatively rapid 1.42 × 10⁻³ to 0.024 s⁻¹ and followed the sequence 2-chlorophenol (2-CP) > 2,6-dichlorophenol (2,6-DCP) > 4-chlorophenol (4-CP) > 2,4-dichlorophenol (2, 4-DCP) > 3-chlorophenol (3-CP). The apparent second-order rate constant was calculated from the measured pseudo-first-order rate constant with respect to CP with initial KMnO₄ concentration (1.5 mM) and follows the same sequence of pseudo-first-order rate constant. This shows that chlorine atoms in the structure of chlorophenol had a significant influence on the oxidation of chlorophenols by potassium permanganate. Permanganate can be used for the treatment of chlorophenol-contaminated soil and groundwater.     

Bayesian 2-Stage Space-Time Mixture Modeling With Spatial Misalignment of the Exposure in Small Area Health Data

We develop a new Bayesian two-stage space-time mixture model to investigate the effects of air pollution on asthma. The two-stage mixture model proposed allows for the identification of temporal latent structure as well as the estimation of the effects of covariates on health outcomes. In the paper, we also consider spatial misalignment of exposure and health data. A simulation study is conducted to assess the performance of the 2-stage mixture model. We apply our statistical framework to a county-level ambulatory care asthma data set in the US state of Georgia for the years 1999?C2008.     

Detection of Vibrio cholerae and Vibrio vulnificus by duplex PCR specific to the groEL gene

Vibrio cholerae and V. vulnificus are of major concern due to their effect on public health throughout the world. It is therefore imperative to identify a gene and method that are suitable for the accurate species-specific detection of these two species. A duplex polymerase chain reaction (PCR) assay was developed using two sets of primers targeting the groEL gene for the accurate simultaneous detection of V. cholerae and V. vulnificus. The nucleotide sequence of the groEL gene was compared with the sequences of other Vibrio and non-Vibrio species. The specificity of two primer sets for duplex PCR was checked using 24 Vibrio and 8 non-Vibrio species. The primer sets were found to be specific for these two species and could detect both of the target bacterial species without any ambiguity, even when comparing closely related species. For both species, the detection limit was 100 pg of purified genomic DNA. The duplex PCR showed high specificity and sensitivity for each species and was sufficient for the detection of V. cholerae and V. vulnificus from artificially infected shellfish tissue, flounder, and even inoculated seawater. This method is simple and cost-effective, and can be utilized for the simultaneous detection of both species, thus representing an effective tool for both epidemiologist and ecologist.     

Allelopathic effects of Mikania cordata on forest and agricultural crops in Bangladesh

Mikania cordata, an invasive weed is becoming a problem in the secondary degraded forests and plantations of Bangladesh, not only competing with but also releasing allelochemicals to cultivated crops. Allelopathic effects of the leaves of M. cordata were investigated through an experiment in the green house of the Institute of Forestry and Environmental Sciences, University of Chittagong, Bangladesh. Five economically important agricultural crops(Oryza sativa L., Triticum aestivum L., Vigna sinensis L., Abelmoschus esculentus L. and Amaranthus tricolor L.) and three forest crops(Acacia auriculiformis A.Cunn. ex Benth. Hook, Albizia procera(Roxb.) Benth.,and Paraserianthes falcataria(L.) Nielson) were used as bioassay species. Experiments were conducted on trays at an average room temperature 27 °C. The effects of different concentrations of leaf extracts were compared to controls. Water soluble allelochemicals of M. cordata inhibited the germination and initial growth of the tested agricultural and forest crops. Germination percent of forest crops declined with increasing concentration of extracts.The inhibitory effect on root elongation of forest crops was pronounced, whereas a stimulatory effect was found on P.falcataria up to a concentration of 25 %. Abelmoschus esculentus showed poor germination(%) and low shoot development(0.5 cm) and no development of taproot or lateral roots at treatment of 100 % concentration. Theinhibitory effect was proportional to the concentrations of the extracts with higher concentrations producing stronger inhibitory effects. Lower concentrations showed some stimulatory effect. The inhibitory effect was pronounced in root and lateral root development rather than germination or shoot development of the crops. Mikania cordata should be eradicated for healthy growth and development of the forest and adjacent agricultural crops.     

Effect of sulphur on biochemical parameters of rapeseed (Brassica campestris L.) in grey terrace soil

An experiment was conducted to study the biochemical response of rapeseed (Brassica campestris L.) to sulphur (S) fertilization at grey terrace soil. There were five treatments: S₀ (control), S₁ (20 kg S ha^?1), S₂ (40 kg S ha^?1), S₃ (60 kg S ha^?1) and S₄ (80 kg S ha^?1). Chlorophyll content in the leaf was determined at 30, 40, 50 and 60 days after emergence (DAE). The biochemical properties were found responsive to S. The highest chlorophyll content of mustard leaves was found in 60 kg S ha^?1 at 50 DAE. The same treatment also showed the maximum N content in the leaves at 45 DAE. The highest oil content was recorded in 60 kg S ha^?1. Other chemical characters such as acid value, peroxide and saponification values were lowest in 60 kg S ha^?1 while iodine value was found highest in the same S level. Non-essential fatty acids such as palmitic, stearic and erucic acid were increased in the rapeseed with decrease in S level, whereas essential fatty acids were maximum in 60 kg S ha^?1. Therefore, 60 kg S ha^?1 can be recommended to produce quality rapeseed in grey terrace soil of Bangladesh.     

Alleviation of drought stress in maize by exogenous application of gibberellic acid and cytokinin

The study was conducted to investigate the ameliorative roles of GA₃ and CK on adverse effects of drought in maize. Drought stressed maize plants were applied with GA₃ and CK at 50, 100, and 150 mg L^?l as foliar spray at the vegetative and the reproductive stages. Plant height, internode length, stem diameter, leaf chlorophyll index, and dry matter production were significantly affected by drought. In most cases, GA₃ and CK significantly improved the depressed plant traits, but in varying degrees depending on the growth stage encountering hormones, and their types and concentrations. Both GA₃ and CK were found to be very effective in alleviating drought-imposed adverse effects on maize at the vegetative phase. Such alleviating effects varied depending on the concentration of the hormones. Application of CK at 150 mg L^?l was excellent resulting in a 106% yield advantage compared to drought stress and 79.9% increase relative to well-watered controls. Conversely, GA₃ at 50 mg L^?l performed well showing 78.8% increase in grain yield. However, both GA₃ and CK had very little effect on improving the depressed growth and yield attributes in maize at the reproductive phase. The relative yield advantages for the hormones were mainly attributed to improving the cob and seed-bearing capacity of drought-stressed maize plants.     

孟加拉国Bhanugach西部保育林用地类型变化(英文)

应用遥感和地理信息系统调查了孟加拉国Sylhet林业分局所辖的Bhanugach西部保育林从1988年到2006年间用地类型的变化。应用了监督和非监督两种方法,用全球定位系统搜集了地面控制点。地理信息系统软件制成地图。结果表明,植被覆盖从1988年的1826hm2大幅地降低到1996年的1714.85hm2,随着协同管理措施的实施,植被覆盖自1996年后逐年增长到2006年的1847.83hm2。在没有其他类型的用地转变成裸地的情况下,裸地变化与植被覆盖间成反比。18年间水体面积从1988年的307.67hm2增加到1996年379.53hm2,96-97年间略有下降,1997年以后直到2006年基本保持不变。本文还提出了将遥感技术和地理信息系统应用于用地类型变化及地理信息系统数据库创建的一些建议。     

Allelopathic effects of leaf litters of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> on some forest and agricultural crops

Allelopathic effects of different doses of Eucalyptus camaldulensis leaf litters were investigated through an experiment in the green house of Institute of Forestry and Environmental Sciences, Chittagong, Bangladesh. Three popular agricultural crops： Falen （Vigna unguiculata）, Chickpea （Cicer arietinum）, Arhor （Cajanus cajan） and two widely used plantation trees： Sada koroi （Albizia procera） and Ipil ipil （Leucaena leucocephala） were selected as bioassay species. Experiment was set on tray at room temperature 27℃. The effects of different doses of leaf litter extracts were compared to the control. Results suggest that leaf litters of E, camaldulesis induced inhibitory effects, It was also found that the effect depend on concentration of extract and litterfall, type of receiver species. Higher concentration of the materials had the higher effect and vice versa. Though all the bioassay species were suppressed some of them showed better performance. Vigna unguiculata, Cicer arietinum are recommended in agroforestry based on this present Experiment output. In mixed plantation, Leucaena leucochephala is a better choice while compared to Albizia procera.     

Non-parametric measures of phenotypic stability in chickpea genotypes (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.)

Multi-environment trials (MET) play an important role in selecting the best cultivars and/or agronomic practices to be used in future years at different locations by assessing a cultivar's stability across environments before its commercial release. Objective of this study is to identify chickpea (Cicer arietinum L.) genotypes that have high yield and stable performance across different locations. The genotypes were developed by various breeders at different research institutes/stations of Iran and the International Center for Agricultural Research in Dray Areas (ICARDA), Syria. Several statistical methods were used to evaluate phenotypic stability of these test chickpea genotypes. The 17 genotypes were tested at six different research stations for two years in Iran. Three non-parametric statistical test of significance for genotype × environment (GE) interaction and ten nonparametric measures of stability analyses were used to identify stable genotypes across the 16 environments. The non-parametric measures (Kubinger, Hildebrand and Kroon/Van der) for G × E interaction were highly significant (P < 0.01), suggesting differential responses of the genotypes to the test environments. Based on high values of nonparametric superiority measure (Fox et al. 1990) and low values of Kang's (1988) rank-sum stability parameters, Flip 94-123C was identified as the most stable genotype. These non parametric parameters were observed to be associated with high mean yield. However, the other nonparametric methods were not positively correlated with mean yield and were therefore not used in classifying the genotypes. Simple correlation coefficients using Spearman’s rank correlation, calculated using ranks was used to measure the relationship between the stability parameters. To understand the nature of relationships among the nonparametric methods, a hierarchical cluster analysis based on non weighted values of genotypes, was performed. The 10 stability parameters fell into three groups.