RESUMO
A cloud monitor instrument, sensing 8-14 microm infrared radiation, has been installed near McMurdo, Antarctica, in order to provide supporting cloud cover information for a high-resolution sky-viewing Fabry-Perot spectrometer experiment. Validation of the cloud monitor observations was performed by a 1 year long comparison with the available 6 h visual cloud observations, expressed in octas (obscured eighths of the sky). The agreement between visual observations and those of the cloud monitor is good--the variation being slightly over one step, or octa--except at the clear sky extreme, which the subjective visual observations tend to overestimate during dark and moonless conditions. Both visual observations and the cloud monitor measurements show an austral winter-summer difference with the winter being clearer.
RESUMO
Field use of surface plasmon resonance (SPR) biosensors for environmental and defense applications such as detection and identification of biological warfare agents has been hampered by lack of rugged, portable, high-performance instrumentation. To meet this need, we have developed compact multi-analyte SPR instruments based on Texas Instruments' Spreeta sensing chips. The instruments weigh 3 kg and are built into clamshell enclosures measuring 28 cm x 22 cm x 13 cm. Functions are divided between an electronics unit in the base of the box and a fluidics assembly in the lid. Automated valves and pumps implement an injection loop flow system that allows sensors to be exposed to sample, rinsed, and treated with additional reagents (such as secondary antibodies) under computer control. Injected samples flow over the surfaces of eight sensor chips fastened into a temperature-controlled silicone flowcell. Each chip has 3 sensing regions, for a total detection of 24 areas that can be simultaneously monitored by SPR. Coating these areas with appropriate antibodies or other receptors allows a sample to be screened for up to 24 different substances simultaneously. The instruments report refractive index (RI) values every second, with a typical noise level of 1-3 x 10(-6) RI units. The design of the device is described, and performance is illustrated with detection of six distinct analytes ranging from small molecules to whole microbes during the course of a single experiment.
