Sterilization by pure oxygen plasma and by oxygen-hydrogen peroxide plasma: an efficacy study.

Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 400 W) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods.

Comparative sterilization effectiveness of plasma in O2-H2O2 mixtures and ethylene oxide treatment.

We investigated the influence of variable parameters of plasma sterilization and compared its effectiveness with that of ethylene oxide using a reactive ion etching plasma reactor at 13.56 MHz. Gases tested were pure oxygen and oxygen-hydrogen peroxide mixtures in 190/10, 180/20, and 160/40 sccm ratios with constant gas flow at 200 sccm, pressure at 0.100 torr, radio-frequency power at 25 W, 50 W, 100 W, and 150 W, and temperature below 60 degrees C. Ethylene oxide sterilization was performed using 450 mg/L at 55 degrees C, 60% humidity, and -0.65 and 0.60 kgf/cm2 pressure. The biological indicator was Bacillus atrophaeus ATCC 9372, with exposure times of 3 to 120 min. Observed D values were 215.91, 55.55, 9.19, and 2.98 min for pure oxygen plasma at 25 W, 50 W, 100 W, and 150 W, respectively. Oxygen-hydrogen peroxide plasma produced D values of 6.41 min (190/10), 6.47 min (180/20), and 4.02 min (160/40) at 100 W and 1.47 min (190/10), 3.11 min (180/20), and 1.94 min (160/40) at 150 W. Ethylene oxide processes resulted in a D value of 2.86 min. Scanning electron microscopy analyses showed damage to the spore cortex.

Use of remote sensing to detect soybean cyst nematode-induced plant stress.

Integrating remote sensing and geographic information systems (GIS) technologies offers tremendous opportunities for farmers to more cost effectively manage the causes of crop stress. Initial soybean cyst nematode (SCN) population densities from 995 2-x-3-m quadrats were obtained from a soybean field near Ames, Iowa, in 2000. The percentage of sunlight reflected from each quadrat was measured weekly using a multispectral radiometer beginning in mid-May and continuing through mid-September. Aerial images were obtained at heights above the field ranging from 45 to 425 m on 12 dates during the soybean growing season. This was accomplished using color film and infrared film in conjunction with a filter to measure reflectance in the near-infrared region (810 nm). Satellite images (Landsat 7) were obtained for five dates during the 2000 growing season. Maps depicting initial SCN population densities, soybean yield, soy oil, and soy protein were generated using the GIS software program ArcView. Percentage reflectance (810 nm), aerial image intensity, and satellite image intensity data then were regressed against soybean yield, soy oil, and soy protein concentrations obtained from each geospatially referenced soybean quadrat. Percentage reflectance measurements explained up to 60% of the variation in initial SCN population densities within soybean quadrats and up to 91% of the variation in soybean yield. Aerial image and satellite image intensities explained up to 80% and 47% of the variation in soybean yield, respectively. Percentage reflectance data also explained 36% and 54% of the variation in oil and protein concentrations of the harvested soybeans, respectively. These results indicate that remote sensing coupled with GIS technologies may provide new tools to detect and quantify SCN population densities and their impacts on the quantity and quality of soybean yield.

Guidance for selecting nuclear instrumentation derived from experience in the Goiânia accident.

Selecting equipment to be used in emergencies is not a simple task. In the radiological accident that occurred in Goiânia, a large variety of instruments from different manufacturers were used, and we observed some of their limitations and advantages. This work presents, in a condensed form, the major problems that occurred with the equipment used in Goiânia and practical observations that could be helpful for instrument selection.

Piroxicam no tratamento de pacientes com dismenorreia primaria. / Piroxican in the treatment of patients with primary dysmenorrhea

40 pacientes com dismenorreia primaria foram tratadas com piroxicam durante tres periodos menstruais seguidos, na posologia de 40 mg (dois primeiros dias) seguida de 20 mg (dois dias seguintes) sempre em dose unica diaria. No primeiro periodo de tratamento, 30 pacientes (75%) ou nao sentiram mais dor ou ela foi de leve intensidade. No segundo periodo, este numero elevou-se para 36 pacientes (90%) e no terceiro periodo, para 37 (92,5%) do total de 40 pacientes tratadas. Somente uma paciente (2,5%) apresentou dor de intensidade leve antes do tratamento. Houve diminuicao da severidade com os periodos de tratamento e regressao precoce da dor (a partir da 4a. hora do primeiro dia de tratamento).Os sintomas associados e o indice de absenteismo tambem diminuiram significativamente. Reacoes adversas leves (epigastralgia, pirose etc) em 6 (15%) pacientes. Conclui-se que o piroxicam e medicamento de escolha para o tratamento da dismenorreia primaria