Biomedical subjects

D E Ciolkosz

Publications and source records attributed to D E Ciolkosz.

3 recordsLinked to original sources

PubMed1998

Imaging of LED arrays for BLSS.

Arrays of light-emitting diodes (LEDS) are being used in life science plant flight experiments and show promise for use in Bioregenerative Life Support Systems (BLSS). However, the small volume available for the systems and the short distances from the LED array necessary in these applications create several unique problems. The discrete LEDS are small and the spacing between the lamps results in significant irradiance variation on surfaces near the array. These irradiance variations make it difficult to use traditional hand-held sensors to measure light levels under the array accurately. The usefulness of rear projection video camera imaging is investigated for the analysis of uniformity of irradiance from an LED array. Irradiance measurements were taken at a high mounting height from the array using both a 400-700-nm quantum sensor and a video camera. Additionally, video images were recorded at different mounting heights from the array. The rear projection imaging technique was suitable for analyzing the irradiance from LED arrays. Comparison of the readings from the video image and the sensor suggests that there is a nonlinear relationship between video image reading and sensor value (R(2) = 0.884). These data also show that the average photosynthetically active radiation level (PAR) does not change as mounting height varies, but that the spatial uniformity of the PAR does increase as mounting height increases. These results are consistent with geometrical analyses of the system.

Ecological Systems, Closed↗

PubMed1998

Microwave lamp characterization.

The operating properties of the SAA microwave lamp developed by Fusion Lighting, Inc. were determined with reference to its usefulness in Bioregenerative Life Support Systems (BLSS). Lamp flux density in several wavelength ranges, spectral output, and temperature response (-10 to +40 degrees C) were determined by mounting the lamp and sensors in a controlled environment chamber. Lamp intensity distribution also was measured using a swing arm apparatus with a 1-m radius. A model was developed to characterize the intensity distribution of the lamp as a function of lamp geometry and output properties. The lamp was found to produce a spectral output similar to that of earlier lamp models, but with a higher photosynthetic output per lumen and per input watt. Radiant energy output was measured to be 0.399 radiant watts per micromole s-1 PAR compared with 0.56 radiant watts per micromoles s-1 PAR for high-pressure sodium lamps. Total lamp output dropped approximately 0.4% for every degree Celsius rise in ambient temperature, with little change in light quality. The intensity distribution of the lamp was found to produce a fairly uniform flux density (+/- 22%) in a 40 degrees cone from lamp nadir.

Ecological Systems, Closed↗

PubMed1998

Towards efficient conversion of electricity into edible biomass in crop production systems: a transgenic approach.

A major problem of controlled environment crop production is the procurement and distribution of adequate light for plant growth. Some electrically efficient light sources lack specific wavelengths required for photomorphogenesis yet provide a light spectrum with a high potential photosynthetic yield. To enable use of these lamps, we describe a concept to genetically modify plants to change their morphogenic responses to light. Photoreceptors in the red and far-red light sensing phytochrome family and the blue light sensing cryptochrome family may be useful to increase or decrease plant sensitivity to regions of the photomorphogenic spectrum. Uses of developmental masterswitches such as COP and DET, and downstream developmental controls, such as the cytokinin biosynthesis enzyme isopentenyl transferase, are also detailed. If photomorphogenic needs can be altered, then lamp selection can be based solely on electrical efficiency of light production and on potential photosynthetic yield from light produced. The combination of lamp electrical efficiency and photosynthetic yield, termed photosynthetic efficacy, was calculated for plant lighting sources. The low-pressure sodium (LPS) and high-pressure sodium (HPS) lamps provide the highest photosynthetic efficacies relative to microwave, metal halide, red and blue light-emitting diodes (LED), and fluorescent lamps. Typically plants grow tall and spindly under LPS or red LED irradiation and in some cases under the broader spectrum of HPS. The strategy of genetic modification of plant light requirements may enable use of electrically efficient and photosynthetically useful red-biased light sources without supplementation from less electrically efficient blue or less photosynthetically useful far-red light sources.

Biomass↗