Automation of Pivot Sprinkler Irrigation Systems to More Efficiently Utilize Rainfall and Irrigation Water

A study was conducted to develop automated pivot sprinkler irrigation systems and determine if such systems use less water and energy than manually operated systems. The study was conducted near Earth, Texas, using irrigation systems located on producers farms. Sensors with transmitters and receivers were constructed and tested so that the irrigation systems can be controlled by wind, soil water tension, and rainfall. The sensors can be used separately or in combination to control the irrigation systems. For several reasons it was not possible to determine if automated systems use less water and energy than manually operated systems. The major reason was the low capacity of the wells (114 to 204 m3/hr) supplying the irrigation systems. To meet crop water requirements and losses due to evaporation and runoff, the well capacity should be at least 284 m3/hr. Since the wells could not supply adequate water, soil water tension was out of the tensiometer range for the last 60 days of the growing season. Considerable variation in soil water tension and content was noted between irrigation systems and within quadrants of each irrigation system. Systems planted to cotton would probably be easier to automate than those planted in corn because of the lower water requirements of cotton. The wind and rainfall controls have more promise to aid in increasing water use efficiency than controls activated by soil water sensors. Wind controls could be used during preirrigation when more time is available to apply water and rainfall controls could be an aid to producers with remotely located irrigation systems

Drug interaction with radiopharmaceuticals: effect on the labeling of red blood cells with technetium-99m and on the bioavailability of radiopharmaceuticals

The evidence that natural and synthetic drugs can affect radiolabeling or bioavailability of radiopharmaceuticals in setting of nuclear medicine clinic is already known. However, this drug interaction with radiopharmaceuticals (DIR) is not completely understood. Several authors have described the effect of drugs on the labeling of blood elements with technetium-99m (99mTc) and on the biodistribution of radiopharmaceuticals. When the DIR is known, if desirable or undesirable, the natural consequence is a correct diagnosis. However, when it is unknown, it is undesirable and the consequences are the possibility of misdiagnosis and/or the repetition of the examination with an increase of radiation dose to the patient. The possible explanation to the appearance of DIR are (a) radiopharmaceutical modification, (b) alteration of the labeling efficiency of the radiopharmaceutical, (c) modification of the target, (d) modification of no target and/or the (e) alteration of the binding of the radiopharmaceutical on the blood proteins. The effect of drugs on the labeling of blood elements with 99mTc might be explained by (i) a direct inhibition (chelating action) of the stannous and pertechnetate ions, (ii) damage induced in the plasma membrane, (iii) competition of the cited ions for the same binding sites, (iv) possible generation of reactive oxygen species that could oxidize the stannous ion and/or (v) direct oxidation of the stannous ion. In conclusion, the development of biological models to study the DIR is highly relevant.<br>A evidência de que drogas naturais ou sintéticas podem afetar a radiomarcação ou a biodisponibilidade de radiofármacos nos procedimentos de medicina nuclear já é bem conhecida. Entretanto, essa interação de droga com radiofármacos (IDR) não está completamente compreendida. Vários autores têm descrito o efeito de drogas na marcação de elementos sanguíneos com tecnécio-99m (99mTc)e na biodistribuição de radiofármacos. Quando a IDR é conhecida, se desejada ou indesejada, a conseqüência natural é um diagnóstico correto. Quando a IDR é desconhecida, ela é indesejada e as conseqüências são a possibilidade de diagnóstico impreciso e/ou a repetição do exame com um aumento de dose de radiação para o paciente. As possíveis explicações para o aparecimento da IDR são (a) modificação do radiofármaco, (b) alteração da eficiência de marcação do radiofármaco, (c) modificação do alvo, (d) modificação do não alvo e/ou (e) alteração da ligação do radiofármaco aos elementos sanguíneos. O efeito de drogas na marcação de elementos sanguíneos com 99mTc poderia ser explicado por (i) uma direta inibição (ação quelante) dos íons estanoso e pertecnetato, (ii) danos na membrana eritrocitária, (iii) competição dos referidos íons pelos mesmos sítios de ligação, (iv) possível geração de espécies reativas de oxigênio e/ou direta oxidação do íon estanoso. Em conclusão, o desenvolvimento de modelos biológicos para o estudo da IDR é altamente relevante