Fundamental investigation of dry electrical discharge machining (DEDM) by optical emission spectroscopy and its numerical interpretation

Dry electrical discharge machining (DEDM) has been developed as an alternative manufacturing process to the traditional EDM in liquid dielectric media. The absence of the liquid dielectric allows DEDM to be performed by simpler and environmentally friendlier machines. The erosion in DEDM mainly occurs due to the bombardment of the workpiece electrode surface by charged particles produced by micro electric discharges. Thus, the understanding of the fundamental properties of the micro plasma is necessary to explain the erosion mechanisms in this process. Optical emission spectroscopy of DEDM single discharges and its numerical interpretation by emission spectra simulation are developed in the present work. The hypothesis of plasmas in local thermal equilibrium (LTE) is developed, whereas the formation of an electron beam in non-LTE plasmas is also considered and briefly introduced. The simulations show that large amount of different ionic species is produced from the anode workpiece material, and the estimated electron temperature profile is peaking at the plasma centre. Moreover, hot anode spots formed on the workpiece surface due to the plasma-material interactions seem to be considerably smaller than the total plasma diameter and the respective eroded crater. These characteristics indicate that DEDM produces discharges similar to anode dominated vacuum arcs, which present properties very different from EDM discharges in liquid dielectric.ISSN:0268-3768ISSN:1433-301

Radiopharmaceuticals drug interactions: a critical review

Radiopharmaceuticals play a critical role in modern medicine primarily for diagnostic purposes, but also for monitoring disease progression and response to treatment. As the use of image has been increased, so has the use of prescription medications. These trends increase the risk of interactions between medications and radiopharmaceuticals. These interactions which have an impact on image by competing with the radiopharmaceutical for binding sites for example can lead to false negative results. Drugs that accelerate the metabolism of the radiopharmaceutical can have a positive impact (i.e. speeding its clearance) or, if repeating image is needed, a negative impact. In some cases, for example in cardiac image among patients taking doxirubacin, these interactions may have a therapeutic benefit. The incidence of drug-radiopharmaceuticals adverse reactions is unknown, since they may not be reported or even recognized. Here,we compiled the medical literature, using the criteria of a systematic review established by the Cochrane Collaboration, on pharmaceutical-drug interactions to provide a summary of documented interactions by organ system and radiopharmaceuticals. The purpose is to provide a reference on drug interactions that could inform the nuclear medicine staff in their daily routine. Efforts to increase adverse event reporting, and ideally consolidate reports worldwide, can provide a critically needed resource for prevention of drug-radiopharmaceuticals interactions.<br>Os radiofármacos desempenham função crítica na medicina moderna, primariamente para fins diagnósticos, mas também no monitoramento da progressão de doenças assim como na avaliação de respostas ao tratamento. O uso da tecnologia por imagem tem crescido e conseqüentemente as prescrições de medicamentos (radiofármacos em especial) com esse propósito. Este fato, aumenta o risco de interações entre medicamentos e radiofármacos. Interações que podem ter um impacto na imagem, podem resultar em falso negativo e assim ter sérias conseqüências para o paciente. Já drogas que aceleram o metabolismo podem ter resultado positivo pois podem aumentar a taxa de eliminação do radiofármaco (clearance acelerado). Contudo, podem ainda ter resultados negativos, se a interação resultar em necessidade de repetição do exame. Em alguns casos, por exemplo em imagem cardíaca, entre pacientes sob o uso de doxarubicina, essas interações podem ter efeito terapêutico. A incidência de efeitos adversos envolvendo radiofármacos é desconhecida, além de não ser oficialmente reconhecida, nem notificada, principalmente no Brasil. Nesse estudo foram compilados da literatura médica, usando a metodologia da revisão sistemática, estabelecida pela Cochrane Collaboration, estudos e relatos de interações medicamentosas com radiofármacos. O objetivo é prover uma referência (sumário) de interações medicametosas com radiofármacos que possa auxiliar a medicina nuclear na sua rotina diária. Contudo, esforços devem ser feitos na tentativa de instituir a notificação de efeitos adversos com radiofármacos, e assim prevenir esse tipo de interação