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Biomedical subjects

B Nicolaï

Publications and source records attributed to B Nicolaï.

7 recordsLinked to original sources
PubMed2005

Spray drift as affected by meteorological conditions.

Spray drift can be defined as the quantity of plant protection product that is carried out of the sprayed (treated) area by the action of air currents during the application process. This continues to be a major problem in applying agricultural pesticides. The purpose of this research is to measure and compare the amount of drift for different climatological conditions under field conditions. Spray drift was determined by sampling in a defined downwind area at different positions in a flat meadow using horizontal drift collectors (sedimenting spray drift) and pipe cleaners (airborne spray drift) for a reference spraying. Meteorological conditions were monitored during each experiment. A drift prediction equation for the reference spraying was set up to predict the expected magnitude of sedimenting drift at various drift distances and atmospheric conditions (wind speed and temperature). This equation can be used to compare measurements using other spraying techniques under different weather conditions to the reference spraying. In 2005, more measurements will be performed to validate the statements and the model reflected in this paper.

Agriculture↗
PubMed2005

A pdpa laser-based measuring set-up for the characterisation of spray nozzles.

The characteristics of agricultural sprays belong to the most critical factors affecting spray drift, deposition on plants, spray coverage and biological efficacy. Hence, within the framework of a research project about agricultural spray drift, a measuring set-up for the characterisation of spray nozzles using a Phase Doppler Particle Analyser (PDPA) was developed. This set-up is able to measure droplet sizes and velocities based on light-scattering principles. It is composed of different parts i.e.: a climate room, a spray unit, a three-dimensional automated positioning system and an Aerometrics PDPA 1D system. This paper presents a detailed description of this measuring set-up along with some first measuring results. These measurements will be used as an input for a Computational Fluid Dynamics drift-prediction model and to classify nozzles based on their driftability.

Agriculture↗
PubMed2001

Structure of manganese diacetate tetrahydrate and low-temperature methyl-group dynamics.

We have determined the crystal structure of manganese(II) diacetate tetrahydrate at 300 and 14 K by single-crystal neutron diffraction. Proton density distributions for each of the three crystallographically distinct methyl groups have been calculated by Fourier difference. At room temperature the observed densities are those of quasi-free rotors. At low temperature rather well localized protons are observed. Inelastic neutron scattering measurements performed with single crystals allow us to assign each of the three tunnelling lines to a particular crystal site. Classical molecular dynamics simulations give density distributions in qualitative agreement with the observations. With quantum mechanics proton distributions can be represented with rotational wavefunctions convoluted with static distributions of librational coordinates. The effective rotational potentials are temperature dependent.

Journal Article↗