摘要:

AbstractThirty‐five dialkyl phenyl phosphates analogous to methyl and ethyl paraoxon were synthesized and their insecticidal activity against house fly (Musca nebulo) determined. Gas chromatographic retention indices (GCRI) at 200°C for all the phosphates were determined on OV‐101, DB‐1701 and DB‐WX fused‐silica capillary columns. The retention indices on polar and nonpolar columns (DB‐1701 and OV‐101, DB‐WX and OV‐101) considered together were shown to be related to the Hansch hydrophobic constant (II). Multiple regression analysis using the least‐square method was carried out to establish the linear relationships between insecticidal activity and GCRI along with the Hammett constant, (σ).The multiple correlation coefficients (r) of various parameters obtained using GCRI were found to be as significant as those obtained using II values. It was found that both hydrophobic and electronic effects made a significant contribution to the insecticidal activity of dialkyl phenyl phosphates. It is concluded that GCRI on two columns can be used directly as an indicator for hydrophobicity in QSAR studies provided that a suitable pair of polar and nonpolar columns is

ISSN:0031-613X    

DOI:10.1002/ps.2780290402

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe concentration of dimethoate in post‐harvest dips needs to be maintained at 400 or 500 mg litre−1to ensure that fruit fly are killed and also to keep residue levels below the MRL. A field unit which contains a colorimeter, a heating block and cooling positions has been evaluated. The diluted dip sample produces a colour with 4‐(p‐nitrobenzyl)pyridine after heating and the addition of tetraethylenepentamine. Precision of the unit was acceptable for a field test (repeatability of ± 10.1%) and there was reasonable agreement between determinations made on the unit and by an HPLC method for a range of dimethoate concentrations from 300 to 700 mg litre−1. The unit can be used at the dip site and the analysis is completed in

ISSN:0031-613X    

DOI:10.1002/ps.2780290403

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractCa2+homeostasis is one of the major regulatory mechanisms operating in the nervous system, with calmodulin translating the Ca2+message into cellular response. To check if hexachlorocyclohexane (HCH) acts as a calmodulin antagonist in the nervous system of rats, the in‐vitro effect of HCH on calmodulin‐dependent Ca2+‐ATPase and cAMP‐phosphodiesterase (PDE) in rat brain has been studied. In the membrane fraction from rat brain, a basal activity of Ca2+‐ATPase was obtained in the absence of Ca2+. Inclusion of Ca2+(1 mM) increased the enzyme activity by 70%. Further, addition of fluphenazine, a potent calmodulin antagonist, inhibited the Ca2+‐dependent enzyme activity (IC50= 85 μM), demonstrating the calmodulin dependence of the enzyme activity. The Ca2+‐ and calmodulin‐dependent Ca2+‐ATPase was inhibited by HCH in a dose‐dependent manner (IC50= 80–90 μM). Ca2+‐ and calmodulin‐dependent cAMP‐PDE from the cytosolic fraction of rat brain was inhibited by HCH (340 μM) by 79%. Addition of excess calmodulin reversed the inhibitory effects of HCH or fluphenazine on Ca2+‐ATPase and cAMP‐PDE, suggesting their direct interaction with calmodulin. By fluorescence interaction studies it has been shown that HCH interacts directly with calmodulin. These studies show that HCH may modulate the intracellular concentration of Ca2+and cAMP, by decreasing the effectiveness of calmodulin towards its effector enzymes, resulting in an altered signal

ISSN:0031-613X    

DOI:10.1002/ps.2780290404

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mobility and decomposition of the herbicide fluroxypyr (4‐amino‐3,5‐dichloro‐6‐fluoro‐2‐pyridyloxyacetic acid) was studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile‐drained plots (clay). Soil samples to a depth of one metre were also collected in both soils to characterize the temporal depth distribution of fluroxypyr in the profiles. The herbicide was applied as the I‐methylheptyl ester of fluroxypyr at two rates, 187.5 and 375.0 g a.e. ha−1, representing the normal and double the dose of the compound used for spring cereals. Some lysimeters received supplementary watering. Only two leachate samples (one from each soil) had concentrations of fluroxypyr above the detection limit (1 μg litre−1), i.e. 2 and 5 μg litre−1. Both samples were collected within two months after application, when less than 2 mm of drainage had been collected. The methylheptyl ester of fluroxypyr was not found in any of the samples. Fluroxypyr levels above the detection limit in soil (5 μg kg−1dry soil), were never found below the topsoil (0.2 m) in the clay profile, while, in the sandy profile, levels just above the detection limit were found occasionally in deeper soil layers. Concentrations were reduced to undetectable or very low levels within

ISSN:0031-613X    

DOI:10.1002/ps.2780290405

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSeveral soil fungi, Aspergillus flavus, A. terreus, Fusarium solani, F. oxysporum,Penicillium citrinumandP. simplicissimumeffectively degrade pendimethalin [N‐(I‐ethylpropyl)‐2,6‐dinitro‐3,4‐xylidine] supplied as sole carbon source in mineral solution. Degradation of pendimethalin by F. solani resulted in the isolation and identification ofN‐propyl‐3‐methyl‐4‐hydroxy‐2,6‐dinitroaniline,N‐(I‐ethylpropyl)‐2‐amino‐6‐nitro‐3,4‐xylidine and 2,6‐dinitro‐3,4‐xylidine. The partial pathways involved in the degra

ISSN:0031-613X    

DOI:10.1002/ps.2780290406

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractTwenty‐four I‐substituted‐I‐aryl‐2‐triazol‐I‐yl‐ethanols were prepared by the reaction between acetylenic, propargylic or allylic organometallics and aryl triazolylmethyl ketones. These were tested for antifungal activity against ten phytopathogenic fungi of different taxonomic classes. EC80values were determined for the seven most active compounds and for two commercial compounds, hexaconazole and flusilazole. In these tests, the fungicidal activity of the new compounds was generally lower than that of the two reference triazoles except for two products which were more active than hexaconazole and flusilazole against powdery

ISSN:0031-613X    

DOI:10.1002/ps.2780290407

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe customer increasingly requires safer and more convenient pesticide formulations. Emulsifiable concentrates and wettable powders are nowadays viewed less favourably by farmers and registration authorities. Suspension concentrates are now common and water‐dispersible granules and emulsions in water are receiving increasing attention. Capsule suspensions offer both safer and more effective performance in favourable cases. For convenience the farmer requires multi‐component products, either as mixtures of active ingredients, which might be as suspoemulsions, or with built‐in enhancing surfactants and oils. Seed treatments are now required as aqueous suspensions and the seed is increasingly of interest as an eficient carrier for pesticides. Research into biological control agents sets the difficult challenge of formulating these products as viable organisms. Three examples of developments are described. These are the applications of polymeric surfactants for suspension concentrates and suspoemulsions, studies of enhancement of pesticide uptake with surfactants and developments in microencapsul

ISSN:0031-613X    

DOI:10.1002/ps.2780290408

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSuspension emulsions or suspoemulsions result from the combination of an emulsion phase, containing one or more active ingredients, with a continuous phase also containing active ingredients but in the form of a solid dispersion. Advantages of such products, which can contain as many as four complementary biologically active ingredients, are elimination of tank mixing; a reduced inventory of products; reduction in the number of applications to a given crop; and savings in time and money. The development of suspoemulsions is discussed and a novel, easy method for their preparation, using latexes, is described. Such products are also useful as feedstock emulsions for other suspension emulsions as well as constituting a stable oil‐in‐water emulsion delivery system in their own ri

ISSN:0031-613X    

DOI:10.1002/ps.2780290409

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe particles constituting a water‐dispersible granule are arranged in a structure which determines the physical properties of that formulation. To examine the importance of such structures, four examples were prepared which were significantly different in terms of bonding and porosity. Examination by electron microscopy and mercury porosimetry indicated that granule strength and dispersion properties were determined by a combination of structure and bonding. A compact granule with weak bonds proved to be a suitable structure for fast dispersion and high solid strengt

ISSN:0031-613X    

DOI:10.1002/ps.2780290410

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA greater public, political and regulatory awareness of chemicals in general, and in particular of their environmental behaviour, has led to increased attention being given to the so called ‘inert’ ingredients of pesticide formulations. Specific controls of these ‘inerts’ have been developed and introduced in the USA whilst in Europe the approach at national and Community level has been more broad‐based. These legislative controls and their associated influence on the labelling and data requirements for pesticide formulations are discussed. The positive move towards ‘safer’ formulations is to be welcomed and will hopefully not lose momentum in the light of increasing regulatory pressure on the individual

ISSN:0031-613X    

DOI:10.1002/ps.2780290411

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY