Search

In this paper, monitoring of amplitude variation in the torsional–axial frequency is proposed for evaluating drill flank wear. Vibration signals were captured from the experiments resulting to the drilling process and investigation was focused on the role of torsional–axial coupling on instability predictions arising as a result of drill flank wear in the frequency spectrum. The first and second modes of torsional axial coupling frequencies were found through use of finite element analysis (FEA) and verified using experimental modal analysis (EMA) by the resonance frequency test. The proposed strategy uses dominant peaks of torsional–axial first mode (Tp1) and second mode (Tp2) frequency. The ratio of torsional–axial amplitudes (TP1/TP2) was considered for the monitoring and the evaluation of drill wear and also to nullify process parameter variation. Drill frequencies verified through experimental study showed their capability of predicting drill flank wear. The validation showed the proposed methodology having 80% accuracy and its ability for effective use for monitoring tool wear.

The paper explains why we get many peaks during gas–liquid chromatography (GC) and attempts to rationalize the complicated GC spectra by identifying the major fragments of synthetic pyrethroids. In the present research, gas chromatography conditions in the electronic ionization (EI) mode were established that served as a benchmark in the development of a chemical ionization (CI) protocol for the selected ester and non-ester synthetic pyrethroids. CI technique is a lower energy process than EI. The lower energy yields less fragmentation, and usually a simpler spectrum with identifiable molecular ion. Common major peak in case of cypermethrin, deltamethrin, fenvalerate, and fenpropathrin was due to meta-phenoxybenzaldehyde moiety at m/z 208 (C14H10NO)+ ion. Etofenprox after protonation of ether oxygen loses one molecule of water producing m/z 359 instead of m/z 377 and it further fragmented to m/z 177 (C12 H17O)+ and 135 (C9H11O)+ ions. Above 70 % recoveries of all the pyrethroids at 0.1 and 1 μg ml−1 levels were achieved from environmental samples. Improving analytical sensitivity and selectivity is important for quantifying trace pyrethroids in matrices. In EI mode, selecting base ion for single ion monitoring or using a precursor ion for MS/MS analysis, the lower limits of quantification (less than 0.1 ppm) become possible for the analysis of synthetic pyrethroids in water.

Bacteria capable of degrading the sulfonated azo dye Red HE7B were isolated from textile mill effluent contaminated soil. The most efficient isolate was identified as Bacillus sp. Azo1 and the isolate could successfully decolorize up to 89 % of the dye. The decolorized cultural extract analyzed by HPLC confirmed degradation. Enzymatic analysis showed twofold and fourfold increase in the activity of azoreductase and laccase enzymes, respectively, indicating involvement of both reductive and oxidative enzymes in biodegradation of Red HE7B. Degraded products which were identified by GC/MS analysis included various metabolites like 8-nitroso 1-naphthol, 2-diazonium naphthalene. Mono azo dye intermediate was initially generated from the parent molecule. This mono azo dye was further degraded by the organism, into additional products, depending on the site of cleavage of R–N=N–R molecule. Based on the degradation products identified, three different pathways have been proposed. The mechanism of degradation in two of these pathways is different from that of the previously reported pathway for azo dye degradation. This is the first report of a microbial isolate following multiple pathways for azo dye degradation. Azo dye Red HE7B was observed to be phytotoxic, leading to decrease in root development, shoot length and seedling fresh weight. However, after biotreatment the resulting degradation products were non-phytotoxic.

Drawbeads are often applied in the deep drawing process to improve control of the material flow during the forming operation. Drawbeads restrain the sheet from flowing freely into die cavity. This paper deals with analysis of effect of draw bead geometry in sheet metal drawing process. Finite element analysis of drawing of circular blanks into axi-symmetric hemispherical cup was done. Circular and rectangular drawbeads were introduced into the Finite Element models and their influence in distribution of strain and thickness were investigated. DYNAFORM and LS-DYNA, a commercially available explicit FEA code were used to model and analyze the forming process respectively. These outcomes are compared with experimental results. The numerical results were found in good agreement with the experimental results. Plastic strain and Von-Mises stresses produced by rectangular drawbeads are higher when compared with the use of circular drawbead. Due to its geometry rectangular drawbead bends and unbends the sheet four times and restrains the material more than circular drawbead.

Mango (Mangiferae indica L.) is an important exporthorticultural crop of India. Various insects and diseasesinfest the fruit especially in the fruiting season. The com-mon insect pests are mango leafhopper, mealy bug, leafwebber, inflorescence midge and fruit fly. The major lossof about 60% is due to leafhopper and mango leafhopper.These pests infest the mango at the floral and bud stage tofruit setting, tender leaves and small fruits. The crop pro-tection measures undertaken to control pest infestation in-volves spray of insecticides along with biological andcultural practices.India produces 65% of the world’s mango crop,9,000,000 MT, but with very little export. Although, Asiaaccounts for 75% world production, its dominance does nottranslate into international trade. The presence of pesticideremnants in mango lowers the export quality of mangofruits in the international market. To increase foreign trade,under the WTO regime, it is imperative to produce pesti-cide free mangoes.The insecticides commonly applied by the farmers areendosulfan, parathion methyl, chlorpyrifos, cypermethrinand fenvalerate. This paper presents a method for theestimation of the multi-class pesticides in mango and theirrecovery.Materials and MethodSolvents like acetone, dichloromethane, hexane (analyticalgrade), were distilled before use. Adsorbents neutral alu-mina and Florisil were activated before use. Pesticidestandards of methyl parathion, endosulfan, chlorpyrifos,cypermethrin and fenvalerate were of analytical gradequality. Gas Chromatogram instrumen-Shimadzu GC-17Afitted with an auto-sampler and ECD detector was used foranalysis. Other minor equipments required were rotaryevaporator and Waring blender, etc.Individual stock standard solutions (1,000 lg/mL) ofparathion methyl, endosulfan, chlorpyrifos, cypermethrinand fenvalerate were prepared in hexane (analytical grade).Working standard solutions of each pesticide was preparedby serial dilutions to 100 lg/mL, which was further dilutedto 0.1–10 lg/mL as per detector response. All the stocksolutions were stored at 4 C. Appropriate aliquot of indi-vidual pesticides solutions were taken and a mixture of fivepesticides of 100 lgmL

Lactofen, a member of the diphenyl ether chemical family, shows great potential for the control of broadleaf weeds associated with leguminous crops. It presents a high degree of selectivity when applied post-emergence to soybean and peanut crops. This paper presents the persistence of lactofen under a soybean crop under various conditions, including without remediation techniques, under soil solarization with polyethene sheets, and soil solarization followed by straw amendment. The results indicate that dissipation is faster when using the soil solarization technique (set II) compared to no treatment (set I) and is further enhanced by tstraw amendment, where almost 90% dissipation was recorded (set III). The dissipation followed first-order kinetics with a half-life that varied from 30 to 10 days. The half-life of lactofen was 15 days in treatments of soil solarization and straw amendments alone, indicating that both techniques have to be used in combination to achieve successful remediation of soil. Use of biodegradable polythene/substitute material will make this process a popular technique and may also improve its commercial viability.

β-Cyfluthrin [α-cyano-4-fluoro-3-phenoxybenzyl-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate] pesticide has been in agricultural use in the recent years for controlling Lepidopteran pests affecting solanaceous crops. The extensive use of synthetic pyrethroids like β-cyfluthrin has resulted in wide spread environmental contamination. The purpose of this study was to isolate bacteria from soil and to determine their ability to degrade β-cyfluthrin and identify the intermediates in culture broth using spectroscopy. An aerobic bacterium capable of degrading β-cyfluthrin was isolated by enrichment culture. The 16S ribosomal DNA sequence of the isolate (strain S1) had 100% identity to the sequence from Pseudomonas stutzeri. Finally products formed during degradation of β-cyfluthrin have been identified as α-cyano-4-fluoro-3-phenoxybenzyl-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (M.W. 341); 4-fluoro-3-phenoxy-α-cyanobenzyl alcohol (M.W. 243) and 3(2,2-dichlorovinyl)-2,2-dimethyl cyclopropanecarboxylic acid (M.W. 208).

A comparative study on residues and rate of dissipation of a new nanoformulation of pyridalyl and commercial pyridalyl was carried out on okra under net house and field conditions. Okra crop was sprayed with commercial and nanoformulation of pyridalyl at recommended (75 g a. i./ha) and double the recommended dose (150 g a. i./ha) at the time of fruiting. Quantitation of residues of pyridalyl in okra was done by ultra high performance liquid chromatography over a period of 15 days, and recovery of the method ranged from 79 to 87 %. The half life calculated from the dissipation pattern of pyridalyl on okra for commercial and developed nanoformulation proved that residues of nanopyridalyl did not persist much longer than that of conventional formulation in net house as well as in field trials. The risk quotient value of pyridalyl in okra was significantly lower than 1, implying its negligible risk to the humans.

A multiresidue method was developed for the estimation of 15 organochlorine pesticides in water. 50 samples of drinking water supplied by the Municipal Corporation to the residential areas of Delhi and 20 ground water samples from nearby villages used for irrigation were monitored for the presence of organochlorine insecticides by the method developed. Although, organochlorine pesticides were detected in the ground water and irrigation water samples, the levels of pesticides were below the Maximum Contaminant Level as prescribed by WHO. No organochlorine insecticides were detected in any of the drinking water samples.

Intensive application of organochlorine pesticides in agriculture and medicinal parasitology coupled with high stability of these pesticides in the environment resulted in their spreading all over the globe.The world over the use of HCH in agriculture has been banned . However , it is still being used in animal sheds and public health . The compulsive use of HCH is the low cost of the insecticide. Its use has recently been banned and the use of lindane is being favoured in agriculture. Lindane is the active constituent of HCH and its use should be beneficial in terms of insect control and it will not pose any environmental problem due to the accumulation of the more persistent beta isomer of HCH. Though, HCH is not used in many countries there are reports of its residues in the environment, probably caused by long range transport from other areas (Cleeman et.al 1995 ). Monitoring of vegetables ( Lal et al. 1969; Mukherjee and Gopal 1996), milk (Mukherjee and Gopal 1993) ,drinking and ground water (Gopal and Mukherjee,1999; Allchin 1991) 1 lakes ( Dua et al. 1998), fishes ((Mugachia et al.1992) have recorded the presence of HCH residues . Because of the ability of HCH to dissolve in fats they get accumulated in the adipose tissues of animals and men (Waliszewskei et.al.1995) and have also been detected in breast milk ( Barkatina et .al .1998) .

Stable nanocolloids of monoclinic sulfur (β-SNPs) were prepared through ‘water-in-oil microemulsion technique’ at room temperature after suitable modifications of the surface. The morphology (rod shaped; ~50 nm in diameter) and allotropic nature (monoclinic) of the SNPs were investigated with Transmission Electron Microscopy and X-ray Diffraction technique. The surface modification, colloidal stability, and surface topology of β-SNPs were evaluated with Fourier Transform Infrared Spectroscopy, zeta potential analysis, and Atomic Force Microscopy. Thermal decomposition pattern of these nanosized particles was determined by Thermo Gravimetric Analysis (TGA). β-SNPs-colloids expressed excellent antimicrobial activities against a series of fungal and bacterial isolates with prominent deformities at their surface. In contrast, insignificant cytotoxicity was achieved against the human derived hepatoma (HepG2) cell line upon treatment with β-SNPs. A simultaneous study was performed to determine the stock concentration of β-SNP-colloids using a novel high phase liquid chromatographic method. Cumulative results of this study hence, elucidate the stabilization of nanosized monoclinic sulfur at room temperature and their potential antimicrobial efficacy over micron-sized sulfur.

India is among a few developing countries where organochlorines are still used for controlling pests due to economic constraints. DDT and HCH are still used for controlling pests of public, health especially malaria vector. The residues of these pesticides are known to find their way into milk and milk products (Mukherjee and Gopal 1992a). In our earlier publication (Mukherjee and Gopal 1992a), baby milk food was not included, it was considered of interest to monitor baby milk food, and animal feed samples for the presence of persistent compounds (Matsumura 1975). For evaluating the level of contamination and for identification of persistent and harmful chemicals, monitoring studies are essential. Besides monitoring of baby milk food and animal feed for organochlorines, vegetables s a m ples were procured for quantifying the residues of various pesticides currently being used in Delhi and surrounding areas. The study can indicate which pesticides need to be banned or require longer waiting period.

A simplified method for estimating extractable residues of oxydemeton methyl (demeton-S-methyl sulphoxide) as its sulphone from crop matrix was developed. Oxydemeton methyl was oxidised with meta-chloroperbenzoic acid (MCPBA) to yield the oxydemeton methyl sulphone (demeton-S-methyl sulphone). The identity of the product was confirmed by IR, H-NMR and mass spectroscopy. The average percent recovery of the procedure is 90–95%. The limit of determination is 0.05 μg/ml.

A simplified method for the determination of chlorothalonil (I) and its metabolite 4-hydroxy-2,5,6-trichloroisophthalonitrile (II) in mustard crop is described. It involves extraction, derivatisation, clean-up on a silica-gel column and gas-liquid chromatography. The retention times and detection limits are 4.49, 5.39 min and 0.01, 0.005 μg/g for I and II, respectively.

Description de cette nouvelle methode, utilisant un chromatographe phase gazeuse Varian 3400 equipe d'un detecteur specifique thermoionique, basee sur la conversion de l'isocyanate de methyle en methylamine et l'obtention d'un derive avec la fluoro-1-dinitro-2,4-benzene (FDNB) et permettant d'obtenir une limite de detection de 10 ng sous forme de derive FDNB. Application a l'analyse d'echantillons vegetaux (ble)