Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Effects of physicochemical soil properties of five agricultural soils on herbicide soil adsorption and leaching
Alister,Claudio; Araya,Manuel; Kogan,Marcelo;
Ciencia e investigación agraria , 2011, DOI: 10.4067/S0718-16202011000200010
Abstract: once pesticides reach the soil, there are several factors that affect their soil behavior. to identify the principal soil and herbicide properties that control their adsorption and leaching, a study of five chilean agricultural and forest soils was performed. simazine, diuron, terbuthylazine and mcpa were applied to the top of 45-cm tall by 12-cm diameter disturbed soil columns, filled with either an andisol, ultisol, entisol or one of two inceptisol soils. after herbicide applications, each lysimeter received 24 mm of simulated rain every 24 hours for five days. once water percolation stopped, the lysimeters were divided into five sections and herbicide concentrations were quantified using high pressure liquid chromatography. relationships between soil physicochemical properties, herbicide sorption (adsorption and desorption) and herbicide leaching were determined. all herbicides exhibited the least depth reached from the andisol soil (10 cm) and the highest from the ultisol soil (45 cm). the principal soil property that affected herbicide adsorption was the soil organic carbon content, specifically the fulvic acid-humins fraction. soil leaching was related to the inverse of soil adsorption (1/kd), cation exchange capacity, humic substances content and herbicide pka. these results suggest that it is possible to develop simple quantitative models to predict the soil-leaching properties of pesticides.
Ecological effects of both single and combined pollution of Cd and bensulfuron-methyl on soil microorganisms

HU Zhu-bang,WANG Hai-zhen,WU Jian-jun,XU Jian-min,

浙江大学学报(农业与生命科学版) , 2005,
Abstract: The most important biological indicators characterizing the soil quality are soil microbial biomass carbon (Cmic), microbial biomass nitrogen (Nmic), soil basic respiration and soil phosphatase and sucrase activities. The dynamic effects of both single and combined pollution of Cd and bensulfuron-methyl herbicide on these biological indicators were studied under laboratory incubation conditions. Under the stress of both single and combined pollution of Cd and bensulfuron-methyl herbicide, the levels of these soil biological indicators were significantly reduced at the initial period, and then gradually increased with time. It was found that there was a significant interaction between Cd and bensulfuron-methyl herbicide in case of combined pollution. The toxicity effect followed the order of combined pollution of Cd and bensulfuron-methyl herbicide > bensulfuron-methyl herbicide >Cd.
Cyclodextrin Inclusion Complex to Improve Physicochemical Properties of Herbicide Bentazon: Exploring Better Formulations  [PDF]
Claudia Yá?ez, Paulina Ca?ete-Rosales, Juan Pablo Castillo, Nicole Catalán, Tomás Undabeytia, Esmeralda Morillo
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0041072
Abstract: The knowledge of the host-guest complexes using cyclodextrins (CDs) has prompted an increase in the development of new formulations. The capacity of these organic host structures of including guest within their hydrophobic cavities, improves physicochemical properties of the guest. In the case of pesticides, several inclusion complexes with cyclodextrins have been reported. However, in order to explore rationally new pesticide formulations, it is essential to know the effect of cyclodextrins on the properties of guest molecules. In this study, the inclusion complexes of bentazon (Btz) with native βCD and two derivatives, 2-hydroxypropyl-β-cyclodextrin (HPCD) and sulfobutylether-β-cyclodextrin (SBECD), were prepared by two methods: kneading and freeze-drying, and their characterization was investigated with different analytical techniques including Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA), X-ray diffractometry (XRD) and differential pulse voltammetry (DPV). All these approaches indicate that Btz forms inclusion complexes with CDs in solution and in solid state, with a stoichiometry of 1:1, although some of them are obtained in mixtures with free Btz. The calculated association constant of the Btz/HPCD complex by DPV was 244±19 M?1 being an intermediate value compared with those obtained with βCD and SBECD. The use of CDs significantly increases Btz photostability, and depending on the CDs, decreases the surface tension. The results indicated that bentazon forms inclusion complexes with CDs showing improved physicochemical properties compared to free bentazon indicating that CDs may serve as excipient in herbicide formulations.
Rapid degradation of bensulfuron-methyl upon repeated application in paddy soils
XIE Xiao-mei,LIU Wei-ping,ABID Subhani,
XIE Xiao-mei
,LIU Wei-ping,ABID Subhani

环境科学学报(英文版) , 2004,
Abstract: Rapid degradation of bensulfuron-methyl upon repeated application in paddy soils was studied. The results showed that the DT _ 50 of bensulfuron-methyl was reduced from 16 d to 9 d in soil with one-year bensulfuron-methyl application. Rapid bensulfuron-methyl degradation was happened to previously untreated soil by addition 5% rapid bensulfuron-methyl adapted soil and was inhibited following pre-treatment with broad-spectrum antibiotic chloramphenicol. In bensulfuron-methyl adapted soil mineralisation of 14 C labeled bensulfuron-methyl to 14 CO_2 occurred at a faster rate than with previously untreated soil. It was concluded that rapid bensulfuron-methyl degradation upon repeated application is probably linked to the adaptation of soil bacteria which can utilize bensulfuron-methyl as a source of carbon and energy.
Physicochemical and morphological characterizations of glyceryl tristearate/castor oil nanocarriers prepared by the solvent diffusion method
Dora, Cristiana L.;Putaux, Jean-Luc;Pignot-Paintrand, Isabelle;Dubreuil, Frédéric;Soldi, Valdir;Borsali, Redouane;Lemos-Senna, Elenara;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012005000066
Abstract: in this study, drug delivery nanocarriers based on glyceryl tristearate and castor oil at different ratios were prepared by the hot solvent diffusion method. peg 660-stearate or poloxamer 188 and soybean lecithin were used as surfactant and co-surfactant, respectively. structural and physicochemical characteristics of the particles were investigated by means of dynamic light scattering (dls), differential scanning calorimetry (dsc), wide-angle x-ray scattering (waxs), atomic force microscopy (afm) and transmission electron microscopy (tem and cryo-tem). dls data indicated that smaller particles were obtained when the liquid lipid was used alone to prepare nanoemulsions (nes). tem and cryo-tem images showed that nes presented spherical particles, whereas solid lipid nanoparticles (slns) and nanostructured lipid carriers (nlcs) presented more complex shapes. slns exhibited lamellar crystal structure, while nlcs displayed a hybrid structure composed of a lamellar crystalline phase in contact with a liquid oil compartment. these experiments contribute to a better understanding of the structure and release performance of these drug carrier systems.

TAO Ling,YIN Li-Yan,LI Wei,
陶 玲
,尹黎燕,李 伟

植物生态学报 , 2008,
Abstract: 稻田施用的除草剂可能会污染邻近水域,对非靶标水生植物产生影响.国家二级重点保护野生植物粗梗水蕨(Ceratopteris pteridoides)主要分布于稻田及其周围水域,其有性繁殖敏感阶段与除草剂施用时间一致,配子体易暴露在除草剂污染中.为了评价除草剂污染对水生态环境特别是对非靶标国家重点保护野生水生植物的影响,保护生物多样性和水生生态环境,该文研究了除草剂苄嘧磺隆(Bensulfuron-methyl)对粗梗水蕨配子体生长和性器官分化的影响.结果表明,苄嘧磺隆对粗梗水蕨孢子萌发没有影响,但对其配子体生长有抑制作用.苄嘧磺隆浓度和粗梗水蕨配子体面积呈明显的剂量.效应关系,苄嘧磺隆对粗梗水蕨配子体生长抑制的EC50(半数效应浓度)为0.086 μg·L-1,低于已报道的环境背景浓度.随着苄嘧磺隆浓度升高,粗梗水蕨的雌雄同体配子体逐渐减少,且配子体上颈卵器形成时间推迟.在苄嘧磺隆为10 μg·L-1时,粗梗水蕨没有雌雄同体配子体形成.以上研究结果表明,低浓度苄嘧磺隆可抑制粗梗水蕨配子体的生长并影响其性器官的分化,使粗梗水蕨有性繁殖能力减弱.
Divya jyothi*,Salma Khanam,Rokeya sultana
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2010,
Abstract: In the present study, simple and rapid microwave-assisted solvent extraction (MASE) technique was developed for the extraction of withanolides in leaves of Withania somnifera and amount of withaferin A in the extracts were quantified by validated HPTLC method. Several variables that can potentially affect the MASE efficiency, namely temperature, irradiation time, power of irradiation and powder size were optimized by means of orthogonal array design procedure. Under optimum conditions, MASE showed significantly higher recoveries and drastic reduction in extraction time than those obtained by conventional extraction method (refluxation and soxhlation). In addition, a drastic reduction of the extraction time (2 min versus 14h) and solvent consumption (20ml versus 50ml) was achieved with MASE when compared with that provided by the conventional method. The effect of microwave on cell destruction of plant material was observed by scanning electron microscopy (SEM).
Physicochemical characterization of a hydrophilic model drug-loaded PHBV microparticles obtained by the double emulsion/solvent evaporation technique
Farago, Paulo V.;Raffin, Renata P.;Pohlmann, Adriana R.;Guterres, Sílvia S.;Zawadzki, S?nia F.;
Journal of the Brazilian Chemical Society , 2008, DOI: 10.1590/S0103-50532008000700011
Abstract: poly(3-hydroxybutirate-co-3-hydroxyvalerate) (phbv) microparticles containing a water-soluble model drug, metformin hydrochloride (mh), were obtained by a double emulsion/solvent evaporation technique. several formulations were prepared in order to investigate the influence of each composition on the encapsulation efficiency (ee). the highest value of ee (9.76%) was obtained using simultaneously ph alkalinization and nacl addition in the external water phase of the formulation. sem study revealed a spherical morphology and a rough surface. the crystalline diffraction intensities for the mh-loaded microparticles were lower than that verified for the physical mixture. ftir results suggested that no chemical bond between the polymer and the drug was formed. also thermal analyses indicated a favorable interaction between mh and phbv. in vitro drug release demonstrated the influence of the phbv on the dissolution profile of mh.
Separation and determination of metsulfuron, bensulfuron, acetochlor by high performance liquid chromatography]

P Zheng,X Xie,P Liu,

色谱 , 1997,
Abstract: In this paper a high performance liquid chromatographic method for the separation and determination of metsulfuron, bensulfuron and acetochlor in the composite herbicide "Nongjiayi" is described. The concentration of methanol in the mobile phase and the temperature of the column affected the k' factor and the separation of the three active ingredients. Impurities in the "Nongjiayi" did not interfere with the determination. Chromatographic conditions were Shim-Pack CLC-C8 (150 mm x 6 mm i.d., 5 microm), mobile phase of methanol-water (60:40, V/V) and UV detector at 240 nm. Quantification was carried out with the three external standards. The average recovery was 98.81% with RSD=0.80% for metsulfuron, 99.10% with RSD=0.78% for bensulfuron and 99.72% with RSD=0.69% for acetochlor. The linear range of this method was 0.10-0.40 microg (r=0.9994) for metsulfuron, 0.40-1.60 microg (r=0.9995) for bensulfuron and 10-40 microg (r=0.9987) for acetochlor. The method is accurate, rapid and reproducible and can be applied to quality control for the "Nongjiayi".
Combined Effects of Chlorsulfuron and Bensulfuron-Methyl Herbicides on the Size of Microbial Biomass in a loamy sand soil  [PDF]
A. M. El-ghamryj,Huang Changyongk,Xu Jianmingk,Xie Zhengmiaok
Pakistan Journal of Biological Sciences , 2000,
Abstract: A laboratory incubation experiment was conducted to examine the combined effects of chlorsulfuron and bensulfuron-methyl herbicides on the soil microbial biomass C (Cmic), N (Nmic), and their ratio in a loamy sand soil. The herbicides were added at four levels that were (C0B0) control, (C1B1) 0.01 & 0.01, (C1B2) 0.01 & 0.1, and (C1B3) 0.01 & 1.0 μg g-1 soil of chlorsulfuron and bensulfuron-methyl, respectively. The soil was then incubated in the dark at 25±1°C. Determinations of Cmic and Nmic were carried out at 1, 3, 5, 7, 10, 15, 25, and 45 days after herbicide application. The results showed that combined applications of herbicides have significant effect on soil microbial biomass C and N, particularly during the first 15 days of incubation, which declined after 25th day of incubation with C1B1 application rate. At 45th day of incubation, the effect of herbicides decreased significantly in C1B2 and it become non-significant as compared with the control. While, C1B3 was still found to be significant as compared to the control and C1B1 but it was at par with C1B2. The results also revealed that with C1B1 treatment the biomass C/N ratio was significantly higher within first 3days of incubation as compared with the control. But with C1B2, the ratio was significantly different within first 5 days of incubation. While with C1B3 the ratio was found significantly higher within first 25 days of incubation as compared with the control. Increasing the application rate resulted in increased inhibitory effect on the soil microbial biomass and also combined addition of herbicides caused negatively more effect than their single application.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.