Delayed neuropathy in sheep by the phosphonothioate insecticide cyanofenphos.

Cyanofenphos (surecide)(R), 25% E.C., O-ethyl O-(4-cyanophenyl) phenylphosphonothioate, was orally administered to one year old lambs at sublethal doses of 1 mg, 2 mg and 4 mg active ingredient kg-1 day-1 for time intervals 60, 45 and 30 days respectively. Irreversible paralytic ataxia symptoms of delayed neuropathy appeared at about 80, 50 and 30 days respectively. In weekly blood samples, AChE (acetylcholine-sterase) and MAO (monoamine oxidase) activities were inhibited depending upon level of dosing and time interval. However no significant correlation was found between the extent of plasma AChE and MAO inhibition and the onset of ataxia symptoms. In brain samples from ataxiated animals, AChE, MAO and NTE (neurotoxic esterase) activities were assayed simultaneously with untreated animal. Direct correlation was shown between in vivo NTE inhibition and the occurrence of delayed neuropathy. Cyanofenphos is the third compound of the phenyl phosphonothioate type on the market showing delayed neuropathy together with Leptophos and EPN.     

Neurotoxicity of organophosphorus insecticides Leptophos and EPN.

Phosfolan, chlorpyrifos, and stirophos when applied to white mice at sublethal doses did not induce any delayed neurotoxic effect. On the other hand, Leptophos and EPN when administered orally at sublethal or lethal levels clearly produced a delayed neurotoxic ataxia in treated mice. The five tested organophosphorus insecticides were compared for their ability to inhibit cholinesterase, neurotoxic esterases and monoamine oxidase. I50 values were estimated for each case. The results revealed that all five compounds were inhibitors of cholinesterase, but only Leptophos and EPN were shown to be potent inhibitors for both neurotoxic esterase and monoamine oxidase in the mouse brain. Additional particular properties of both Leptophos and EPN were found in their ability to cause delayed neurotoxic ataxia in chickens and sheep fed once on sublethal doses of these compounds. It is believed that the phosphonate ester configuration of EPN and Leptophos has a specific mode of toxic action which is mainly located at the central nervous system. It is also postulated that these delayed neurotoxic agents might inhibit postganglionic sympathetic neurons, thus resulting in chronic paralytic effects.     

Acute toxicity of two insecticides to tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri

Acute toxicity and presumable harmless concentration of two commercial insecticides, Furadan 3G and Malataf 50E were reported for tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri. L. hoffmeisteri were found more susceptible to both the insecticides; the Furadan was found to be more toxic than Malataf to tubificid worms. Analysis of variants showed a significant difference between safe concentrations of the same insecticide to different species.     

Thermodynamics of metal cation binding by a solid soil derived humic acid. 2. Binding of Mn(II), Co(NH3)6aq3+ and Hg(II)

Metal binding is an important function of humic acids (HAs) in soils, sediments and waters. At pH 2.0, Mn(II) and Co(NH3)6aq3+ bind tightly in one step labeled A to a solid humic acid NHA isolated from a New Hampshire soil. Two consecutive steps are observed for Hg(II) binding. All the binding isotherms fit the Langmuir model in the temperature range 10.0-50.0 degrees C. Stoichiometric site capacities indicate predominant binding by charge-neutralizing HA carboxylate groups for Mn(II) and the second step A of Hg(II) binding. The binding affinity order in step A is Co(NH3)(6)3+>Hg(II)>Mn(II). Metal binding enthalpy and entropy changes fit the linear correlation found previously for binding of other metal cations by solid HAs. Free energy buffering from cooperative enthalpy and entropy changes and lower enthalpies for metal-HA interactions in solution suggest that desolvation of the cations and HA binding sites as well as HA conformational changes to allow for inner-sphere complexation predominate metal binding by hydrated solid HAs.     

Mode choice model for vulnerable motorcyclists in Malaysia

OBJECTIVE: In developing countries, motorcycle use has grown in popularity in the past decades. Commensurate with this growth is the increase in death and casualties among motorcyclists in these countries. One of the strategic programs to minimize this problem is to reduce motorcyclists exposure by shifting them into safer modes of transport. This study aims to explore the differences in the characteristics of bus and motorcycle users. It identifies the factors contributing to their choice of transport mode and estimates the probability that motorcyclists might change their travel mode to a safer alternative; namely, bus travel. METHODS: In this article, a survey of 535 motorcycle and bus users was conducted in seven districts of Selangor state, Malaysia. A binary logit model was developed for the two alternative modes, bus and motorcycle. RESULTS: It was found that travel time, travel cost, gender, age, and income level are significant in influencing motorcyclists' mode choice behavior. The probability of motorcycle riders shifting to public transport was also examined based on a scenario of a reduction in bus travel time and travel cost. CONCLUSIONS: Reduction of total travel time for the bus mode emerges as the most important element in a program aimed at attracting motorcyclists towards public transport and away from the motorcycle mode.     

Smoldering combustion of dust layer on hot surface

The critical temperature as well as the critical flux for ignition of a dust layer of cornflour and a mixture of wheatflour and cornflour (80% wheatflour+20% cornflour) on a hot plate have been determined. The moulded sample was cylindrical in shape and of different heights and diameters. The particle size of dusts ranged between 63 μm to 150 μm. The temperature–time histories for self-heating without ignition and with ignition are offered, showing the critical boundaries between them. Also the times to ignition for each dust, showing the effect of sample size on their values, are determined. Certain experimental correlations which relate to times to ignition, as well as the critical temperature for ignition and thermal and geometrical dimensions of sample are presented.     

Water quality monitoring of Al-Habbaniyah Lake using remote sensing and in situ measurements

Environmental Monitoring and Assessment - A good quality drinking water is essential for human survival. However, a large percentage of the populations in most developing countries (Nigeria...