Evaluation of plants used for the control of animal ectoparasitoses in Southern Ethiopia (Oromiya and Somali regions)

The burden of ticks in semi-arid lands of Ethiopia is not as pronounced as in some more humid areas of the continent. Nevertheless, the increasing recourse to chemicals smuggled by illegal traders has led to serious problems, including poisoning of humans and animals, discontinuous and irrational treatment regimens, tick-resistance to acaricidal products, loss of traditional knowledge and weakening of social structures. In order to encourage a resumption of the long-established ethnoveterinary practices, a survey on plants locally used in tick control was undertaken, and plant species used in other parts of the continent for the same purpose were considered. On these bases, 28 plant species or varieties were collected in the study area: Acacia seyal var. seyal, Adenium somalense, Aloe calidophila, Aloe parvidens, Azadirachta indica, Boscia angustifolia, Calotropis procera, Calpurnia aurea, Cissus quadrangularis, Commiphora erythraea, Cordia africana, Croton macrostachys, Croton megalocarpus, Datura stramonium, Euphorbia candelabrum, Euphorbia tirucalli, Ficus sycomorus, Ficus thonningii, Lantana camara, Maerua triphylla, Ocimum suave, two varieties of Ricinus communis (one with green fruits and another with red ones), Solanum incanum, Solanum somalense, Sterculia rhynchocarpa, Tagetes minuta and Vernonia amygdalina. In general, leaves were collected and used. However, due to the scarcity of foliar material, the whole plant of T. minuta and O. suave, the whole stem of A. somalense and C. quadrangularis, the branches of E. candelabrum and E. tirucalli, the bark in the case of A. seyal, C. erythraea and S. rhynchocarpa, were examined. After drying and grinding, the plant material was extracted with hexane and acetone, and made up to different concentrations to test the relevant repellent and toxic properties on adult Rhipicephalus pulchellus unfed ticks. For every bioassay, four replications, each using ten ticks, were performed. For the repellency bioassays, ticks were placed on a rectangular polystyrene platform stuck in a plastic basin and surrounded by water, in order to prevent them from moving away. Two glass rods, each provided with filter paper at the top and at the base, were inserted at opposite edges of the platform. The two filter papers of one rod were impregnated with the testing solution (i.e. solvent plus extract) at different concentrations while those of the other rod were treated with the pertinent extractant (hexane or acetone). Because of their inherent tendency to climb, most of the ticks settled onto the rods (mainly at the top), and their distribution was different depending on the repellency capacity of the extracts. The relevant data were then converted into repellency indexes using the formula [(Nc - Nt)/(Nc + Nt)] x 100, where Nc refers to the number of ticks on the control rod and Nt to the number of ticks on the test rod (Lwande et al., 1999; Pascual-Villalobos and Robledo, 1998). For the toxicity bioassays, 1 ìl of the extract at different concentrations was placed onto each tick and the mortality or weakening ratio was recorded after 24 hours. Because of the intrinsic toxicity of hexane, only acetone extracts were used for these assays. Due to the efficacy in extracting volatile compounds, hexane extracts had, for 24 plant species, better repellent properties than acetone extracts. Moreover, at a concentration of 10%, four species had negative repellency indexes with hexane extracts and five with acetone ones. At such concentration, these extracts therefore seemed to attract the ticks rather than repel them. At a concentration of 10%, thirteen hexane and five acetone extracts had repellency indexes > 50. At a concentration of 5%, only five hexane extracts and no acetone ones exceeded this value. Finally, only one species had a repellency index > 50 with the hexane extract at a 1% concentration. The plants showing good repellency indexes with at least one of the two solvents were A. calidophila, C. quadrangularis, C. erythraea, C. macrostachys, C. megalocarpus, D. stramonium, L. camara, M. triphylla, O. suave, the two varieties of R. communis and T. minuta. Amomg them, from a practical point of view, it is suitable to concentrate on O. suave, T. minuta and, to a certain extent, A. calidophila. In fact, C. quadrangularis, C. erythraea, C. macrostachys, D. stramonium, M. triphylla and the two varieties of R. communis had good repellent properties using hexane extracts at 10%, but not at 5%. Because trees like C. erythraea, C. macrostachys, C. megalocarpus and M. triphylla are highly valuable in a very dry environment, an excessive exploitation can put them in danger. Since D. stramonium, L. camara and R. communis are toxic plants, their extracts can be a serious threat for both humans and animals. Furthermore, L. camara is one of the worst weeds in the world, making it very inappropriate for lands already subject to the problem of bush encroachment. For all these reasons, T. minuta and O. suave appear to be the most promising plants; moreover, they are very well known in Southern Ethiopia and occur widely all over the area. On the contrary, A. calidophila is limited to just some places and the cultivation of Aloe species needs special attention, so it is not very suitable for people with a nomadic lifestyle. Concerning the toxicity bioassays, C. aurea extracts yielded by far the best results. In fact, all the ticks used had severe movement impairment when put in contact with acetone extracts at the concentrations of 20% and 10%. At a 5% concentration, 85% of the ticks had the same symptoms. In a separate test, a 10% water extract had a similar effect on 30 ticks out of 40, demonstrating the ease of extraction and application of the active compounds. The plant is well known, mainly by the Borana pastoralists, and is resistant to drought. It is also well able to grow in overgrazed areas, and its cultivation does not require special skills. Some of the extracts of other species gave good or fair results in the toxicity bioassays but, apart from S. incanum, only at a very high concentration (20%). Further studies may include isolation and characterization of the active compounds from the best species, setting up of a suitable plan for livestock treatment, and organization of a production and distribution cycle of appropriate phytomedicines in the pertinent pastoral area.Dissertation (MSc (Veterinary Science))--University of Pretoria, 2007.Paraclinical Sciencesunrestricte

Ion mobility mass spectrometry with surface activated chemical ionisation as a method for studying the domain of water clusters

Water holds great relevance in various biological and biochemical systems. Water behaves as an excellent solvent, a reactant, a product and a catalyst of the reaction. The organisation of the water molecules, synergised by hydrogen bonds, builds up the structure of the water clusters. These water clusters significantly influence biological functions. To study the domain of water clusters using Ion mobility mass spectrometry with surface activated chemical ionisation. The experimental analysis was aimed to determine the water behaviour in terms of cluster formation before and after the application of a physical effect, namely low-frequency irradiation. A sanist platform-based spectrometer, manufactured by ISB srl with SACI version for protein analysis, was used as the equipment. Furthermore, for samples, we used pure de-ionised water, a part of which was used virgin, and another part was irradiated. Ion-mobility mass spectrometry (IM-MS) procedure was adopted as the experimental method. An electromagnetic frequency fields generator was used to subject the test samples to electromagnetic radiations between 7 Hz to 80 Hz. The presence of neutral water species was confirmed in the water samples. For the same m/z, water ion clusters in the untreated water were found to have a much higher intensity than the electromagnetically treated water. The presence of a water cluster near the (M+H)+ in electromagnetically treated dilute arginine solution was also confirmed. It is possible to detect water ion clusters by using Ion mobility mass spectrometry and SACI with low surface potential (47 V). The water cluster formation and its characteristics were found to be different in the treated and non-treated water. The electromagnetic radiations of low frequency seem to affect the hydrogen bonds of the water molecules

Testing the Properties of Beam-Dose Monitors for VHEE-FLASH Radiation Therapy

Very High Energy Electrons (VHEE) of 50 - 250 MeV are an attractive choice for FLASH radiation therapy (RT). Before VHEE-FLASH RT can be considered for clinical use, a reliable dosimetric and beam monitoring system needs to be developed, able to measure the dose delivered to the patient in real-time and cut off the beam in the event of a machine fault to prevent overdosing the patient. Ionisation chambers are the standard monitors in conventional RT; however, their response saturates at the high dose rates required for FLASH. Therefore, a new dosimetry method is needed that can provide reliable measurements of the delivered dose in these conditions. Experiments using 200 MeV electrons were done at the CLEAR facility at CERN to investigate the properties of detectors such as diamond beam loss detectors, GEM foil detectors, and Timepix3 ASIC chips. From the tests, the GEM foil proved to be the most promising

REFLECT – Research flight of EURADOS and CRREAT: Intercomparison of various radiation dosimeters onboard aircraft

Aircraft crew are one of the groups of radiation workers which receive the highest annual exposure to ionizing radiation. Validation of computer codes used routinely for calculation of the exposure due to cosmic radiation and the observation of nonpredictable changes in the level of the exposure due to solar energetic particles, requires continuous measurements onboard aircraft. Appropriate calibration of suitable instruments is crucial, however, for the very complex atmospheric radiation field there is no single reference field covering all particles and energies involved. Further intercomparisons of measurements of different instruments under real flight conditions are therefore indispensable. In November 2017, the REFLECT (REsearch FLight of EURADOS and CRREAT) was carried out. With a payload comprising more than 20 different instruments, REFLECT represents the largest campaign of this type ever performed. The instruments flown included those already proven for routine dosimetry onboard aircraft such as the Liulin Si-diode spectrometer and tissue equivalent proportional counters, as well as newly developed detectors and instruments with the potential to be used for onboard aircraft measurements in the future. This flight enabled acquisition of dosimetric data under well-defined conditions onboard aircraft and comparison of new instruments with those routinely used. As expected, dosimeters routinely used for onboard aircraft dosimetry and for verification of calculated doses such as a tissue equivalent proportional counter or a silicon detector device like Liulin agreed reasonable with each other as well as with model calculations. Conventional neutron rem counters underestimated neutron ambient dose equivalent, while extended-range neutron rem counters provided results comparable to routinely used instruments. Although the responses of some instruments, not primarily intended for the use in a very complex mixed radiation field such as onboard aircraft, were as somehow expected to be different, the verification of their suitability was one of the objectives of the REFLECT. This campaign comprised a single short flight. For further testing of instruments, additional flights as well as comparison at appropriate reference fields are envisaged. The REFLECT provided valuable experience and feedback for validation of calculated aviation doses

Evaluation en corpus de l'application des recommandations orthographiques de 1990 en France et en Suisse : le cas des emprunts

Ce mémoire propose une observation comparée de l'application des rectifications orthographiques de 1990 dans la presse française et suisse, au moyen d'une exploration de corpus outillée. Il contient un rappel historique de l'orthographe française et de ses réformes au cours du temps, une présentation du projet de rectifications orthographiques de 1990 et des unités lexicales concernées, puis une explication sur la méthodologie employée pour observer de tels phénomènes en corpus, notamment au moyen d'outils de calcul de fréquences et de lexicométrie. Enfin, quelques résultats sont discutés suite à ces observations

patogeni floematici della vite : identificazione, epidemiologia, prevenzione

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patogeni floematici della vite : identificazione, epidemiologia, prevenzione

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