Modified Fenton reaction for trichlorophenol dechlorination by enzymatically generated H2O2 and gluconic acid chelate

Glucose oxidase is a well-known enzyme that catalyzes the oxidation of β-d-glucose to produce gluconic acid and hydrogen peroxide. Fenton reaction is a powerful oxidation technology used for the oxidation of groundwater pollutants. For the application of Fenton reaction in groundwater remediation, successful operation of Fenton reaction near neutral pH, and on-site generation of both H₂O₂ and chelate will be beneficial. The focus of this experimental study was to couple the glucose oxidation reaction with chelate-based Fenton reaction. The idea was to use the hydrogen peroxide and chelate gluconic acid generated during glucose oxidation for the dechlorination of 2,4,6-trichlorophenol (TCP) by Fenton reaction. The oxidation of glucose was achieved using the enzyme in free and immobilized forms. The rate of production of hydrogen peroxide was determined for each system, and was used to estimate the time required for complete consumption of glucose during the process, thus avoiding any traces of glucose in the Fenton reaction. In the case of free enzyme reaction, separation of the enzyme was achieved using an ultrafiltration membrane before initiating the Fenton reaction. The oxidation of TCP by Fenton reaction was performed at varying ratios of gluconic acid/Fe, and its effect on the decomposition of TCP and H₂O₂ was studied. TCP degradation was studied both in terms of parent compound degradation and free chloride generation.     

Development of an analytical method for analysis of flubendiamide,des-iodo flubendiamide and study of their residue persistence in tomato and soil

Flubendiamide is a new insecticide that has been found to give excellent control of lepidopterous pests of tomato. This study has been undertaken to develop an improved method for analysis of flubendiamide and its metabolite des-iodo flubendiamide and determine residue retention in tomato and soil. The analytical method developed involved extraction of flubendiamide and its metabolite des-iodo flubendiamide with acetonitrile, liquid-liquid partitioning into hexane-ethyl acetate mixture (6:4, v v^?1) and cleanup with activated neutral alumina. Finally the residues were dissolved in gradient high pressure liquid chromatography (HPLC) grade acetonitrile for analysis by HPLC. The mobile phase, acetonitrile-water at 60:40 (v v^?1) proportion and the wavelength of 235 nm gave maximum peak resolution. Using the above method and HPLC parameters described, nearly 100 % recovery of both insecticides were obtained. There was no matrix interference and the limit of quantification (LOQ) of the method was 0.01 mg kg^?1. Initial residue deposits of flubendiamide on field-treated tomato from treatments @ 48 and 96 g active ingredient hectare^?1 were 0.83 and 1.68 mg kg^?1,respectively. The residues of flubendiamide dissipated at the half-life of 3.9 and 4.4 days from treatments @ 48 and 96 g a.i. ha^?1, respectively and persisted for 15 days from both the treatments. Des-iodo flubendiamide was not detected in tomato fruits at any time during the study period. Residues of flubendiamide and des-iodo flubendiamide in soil from treatment @ 48 and 96 g a.i. ha^?1 were below detectable level (BDL, < 0.01 mg kg^?1) after 20 days. Flubendiamide completely dissipated from tomato within 20 days when the 480 SC formulation was applied at doses recommended for protection against lepidopterous pests.     

Prenatal diagnosis of Harlequin ichthyosis presenting as distal arthrogryposis using three-dimensional ultrasound

We describe a case of Harlequin Icthyosis where the main 2D and 3D ultrasound findings were digital contractures as opposed to the more commonly described severe facial dysmorphisms. A prenatal finding of distal arthrogryposis can therefore include harlequin icthyosis as a differential diagnosis, where 3D ultrasound may then disclose the facial features more commonly associated with the condition. Copyright © 2007 John Wiley & Sons, Ltd.     

Research needs for improving biofuel burning cookstove technologies

The contribution of the household biofuel cooking energy system in developing countries to anthropogenic emissions of greenhouse gases is significant and a potential exists to halve this contribution cost-effectively. A review of past programmes aimed at disseminating stoves designed to reduce fuel consumption and exposures shows these programmes to have been only partially successful. If future programmes are to achieve their intended societal objectives and satisfy consumer requirements, research on designing improved stoves with lower emissions is critical. Integrated research will also be required on other related aspects, such as measurements of emissions from various stove-biofuel combinations, and on developing improved procedures for testing, evaluation and dissemination. The multiple benefits that can accrue from these programmes makes continuing and increased investment of efforts worthwhile.     

Safety evaluation of flubendiamide and its metabolites on cabbage and persistence in soil in different agroclimatic zones of India

Supervised field trials following good agricultural practices were conducted at the research farms of four agricultural universities located at four different agroclimatic zones of India to evaluate the persistence and dissipation of flubendiamide and its metabolite, des-iodo flubendiamide, on cabbage. Two spray applications of flubendiamide 480 SC of standard and double dose at the rate of 24 and 48 g a.i. ha^?1 were given to the crop at a 15-day interval, and the residues of flubendiamide 2 h after spray were found in the range of 0.107–0.33 and 0.20–0.49 mg kg^?1 at respective doses. Residue of des-iodo flubendiamide was not detected in any cabbage sample during study period. No residues were found in the soil samples collected from all treated fields after 15 days of application. On the basis of data generated under All India Network Project on Pesticide Residues, a preharvest interval (PHI) of 10 days has been recommended, and the flubendiamide 480 SC has been registered for its use on cabbage by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of flubendiamide on cabbage has been fixed by the Ministry of Health and Family Welfare, Government of India, under Food Safety Standard Authority of India as 0.05 μg/g after its risk assessment.     

Emissions from burning biofuels in metal cookstoves

Promoting stoves that burn wood and other biofuels more efficiently is one of the means to reduce fuel consumption, but such efficient stoves may also emit more carbon monoxide and total suspended particulates. In an earlier study, a standard chamber method was proposed to estimate emission factors from burning fuelwood (Acacia nilotica). Here that methodology is extended to measure emission factors from burning of dungcakes and crop residues (Brassica or mustard stalks)—common fuels in many developing countries. The amounts of carbon monoxide (CO) and total suspended particulates (TSP) emitted by four different models of stoves, when using each of the three biofuels, are measured.The CO emission factors range from 13–68 (g/kg) for fuelwood to 26–67 g/kg for dungcakes and 20–114 g/kg for crop residues, for particulates they range from 1.1–3.8 to 4.1–7.8 and 2.1–12.0 g/kg for the three fuels, respectively. On a per unit heat delivered basis, the emissions of CO and TSP from both dungcakes and crop residues are two to three times higher compared to those from fuelwood. While for some improved stove-fuel combinations, the increase in emission factors was offset by the increase in thermal efficiency, this was not always so and causes a dilemma. The more efficient stoves are found to have higher emission factors of both CO and TSP for all three fuels. Emissions per standard task (i.e, on a unit heat delivered basis) is proposed as a criterion to evaluate cookstoves.     

Simulating nitrate drainage losses from a Walnut Creek watershed field

This study was designed to evaluate the improved version of the Root Zone Water Quality Model (RZWQM) using 6 yr (1992-1997) of field-measured data from a field within Walnut Creek watershed located in central Iowa. Measured data included subsurface drainage flows, NO3-N concentrations and loads in subsurface drainage water, and corn (Zea mays L.) and soybean [Glycine mar (L.) Merr.] yields. The dominant soil within this field was Webster (fine-loamy, mixed, superactive, mesic Typic Endoaquolls) and cropping system was corn-soybean rotation. The model was calibrated with 1992 data and was validated with 1993 to 1997 data. Simulations of subsurface drainage flow closely matched observed data showing model efficiency of 99% (EF = 0.99), and difference (D) of 1% between measured and predicted data. The model simulated NO3-N losses with subsurface drainage water reasonably well with EF = 0.8 and D = 13%. The simulated corn grain yields were in close agreement with measured data with D < 10%. Nitrogen-scenario simulations demonstrated that corn yield response function reached a plateau when N-application rate exceeded 90 kg ha(-1). Fraction of applied N lost with subsurface drainage water varied from 7 to 16% when N-application rate varied from 30 to 180 kg ha(-1) after accounting for the nitrate loss with no-fertilizer application. These results indicate that the RZWQM has the potential to simulate the impact of N application rates on corn yields and NO3-N losses with subsurface drainage flows for agricultural fields in central Iowa.     

Residual behavior and risk assessment of flubendiamide on tomato at different agro-climatic conditions in India

Supervised field trials were conducted at four different agro-climatic zones in India to evaluate the dissipation pattern and risk assessment of flubendiamide on tomato. Flubendiamide 480 SC was sprayed on tomato at 48 and 96 g active ingredient (a.i.) ha^?1. Samples of tomato fruits were drawn at 0, 1, 3, 5, 7, 10, 15, and 20 days after treatment. Quantification of residues was done on a high-performance liquid chromatography (HPLC) device with a photo diode array detector. The limit of quantification (LOQ) of this method was found to be 0.01 mg kg^?1 while limit of detection (LOD) being 0.003 mg kg^?1. Residues of flubendiamide were found below the determination limit of 0.01 mg kg^?1 in 20 days at both the dosages in all the locations. The half-life of flubendiamide at an application rate of 48 g a.i.?ha^?1 varied from 0.33 to 3.28 days and at 48-g a.i. ranged from 1.21 to 3.00 days. On the basis of data generated under the All India Network Project on Pesticide Residues, a preharvest interval (PHI) of 1 day has been recommended, and the flubendiamide 480 SC has been registered for its use on tomato by the Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of flubendiamide on tomato has been fixed by the Ministry of Health and Family Welfare, Government of India under Food Safety Standard Authority of India, as 0.07 μg g^?1 after its risk assessment.