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At least 289 records · Page 16Linked to original sources
PubMed1994

Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures.

Two CELSS candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. With the exception of increased crude fiber of soybean seed with increased CO2, no trends were apparent with regard to CO2 effects on proximate composition of soybean seed and potato tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.

Atmospheric Pressure↗
PubMed1980

Effect of ambient temperature and humidity on urine output in sheep.

Urine output, respiratory rate, water intake, plasma and urine osmolalities, and PCV of 6 sheep exposed to 4 weeks of each of hot-humid, hot-dry, and cool-humid environments alternated with 3 weeks each of cool-dry control environments were determined. Compared with urine output during the control environment, urine output increased during hot-humid, hot-dry, and cool-humid exposure, but was 70% greater during the hot-humid environment than during hot-dry exposure. Water intake increased 37% to 45% during hot-dry exposure but decreased 35% during the first 2 weeks of cool-humid exposure. Urine osmolality decreased 38%, 22%, and 44% during hot-humid, hot-dry, and cool-humid exposure, respectively, whereas plasma osmolality values only increased 3% during hot-dry exposure. Respiratory rates increased on exposure to both hot environments, but decreased during cool-humid exposure. The PCV decreased 3% after 1 week of hot-humid exposure, 8% after 4 weeks of hot-dry exposure, and 5% after 4 weeks of cool-humid exposure. Urine output, and probably plasma volume, increased during these periods because evaporative heat loss was reduced due to the lack of adequate air convection and mobility. Heat loss through increased urine output was not significant (P less than 0.2). Enclosed sheep should be kept with short fleeces and should be maintained in conditions of low temperature and adequate convection if representative physiologic, biochemical, and pharmacologic assessments are desired.

Animals↗
PubMed1976

Water exchange in rats exposed to cold, hypoxia, and both combined.

Male rats were exposed chronically to cold (5 degrees C air), hypoxia (12% oxygen in nitrogen), and both combined. Intake of water and food, as well as urinary excretion, were measured during both a 5-d pretreatment control period and throughout the first 3 weeks of the treatment period. Regression analysis of water intake on urine output revealed that, at a given water intake, all three treated groups excreted significantly more urine than controls. No significant differences occurred among treated groups. Serum osmolalities of all three treated groups, measured at the end of the 48-d treatment period, were elevated significantly above the level of the control group. All treated groups also manifested a thirst immediately following return to control environment (26 degrees C, 20.9% oxygen). Water intakes of all three treated groups were significantly greater than that of the control group during the first 2 h after return to control environment. Thus, the three treated groups appeared to be dehydrated relative to the control group. The results further suggest that the effect of combined cold (5 degrees C) and hypoxia (12% oxygen) on water exchange is not a summation of that occurring separately during cold and hypoxia. The factors inducing dehydration in cold and hypoxia are apparently related to increased evaporative water loss and to alterations in thirst and renal mechanisms.

Animals↗
PubMed1984

Photosynthetic response and adaptation to high temperature in desert plants : a comparison of gas exchange and fluorescence methods for studies of thermal tolerance.

The temperature threshold for the onset of irreversible loss of photosynthetic capacity of leaves was examined in studies of net CO(2) exchange and by chlorophyll fluorescence techniques. Close agreement was found between the temperature threshold for a dramatic increase in the fluorescence of chlorophyll from intact leaves and the leaf temperature at which the capacity for photosynthetic CO(2) fixation (measured at rate saturating light intensity by infrared gas analysis) began to be temperature unstable (i.e. decline with time of exposure to a constant temperature). This decline in CO(2) uptake was not a result of a stomatal response yielding a reduced intercellular CO(2) concentration at high temperature, and it is interpreted as an indication of progressive damage to some essential component(s) of the leaf. The temperature-dependent change in chlorophyll fluorescence apparently also indicated the onset of this damage. The fluorescence assay could be conducted with discs of leaves collected from remote locations and kept moist while they were transported to a central location, allowing assessment of the high temperature tolerance of leaves which developed under natural field conditions. These assays were verified using a mobile laboratory to study gas exchange of attached leaves in situ. The high temperature sensitivity of leaves of plants growing under natural conditions were similar to those of the same species grown in controlled environments of similar thermal regimes. High temperature in controlled environment studies brought about acclimation responses which increased the threshold for high temperature damage as measured by gas exchange. Studies of fluorescence versus temperature confirmed that this method could be used to quantify these responses, and permitted the kinetics of the acclimation response to be examined. Gas exchange studies, while providing similar estimates of thermal stability, required more time, more elaborate instrumentation, and are particularly difficult to conduct with field plants growing in situ.

Journal Article↗
PubMed1999

Regulating plant/insect interactions using CO2 enrichment in model ecosystems.

The greenhouse environment is a challenging artificial ecosystem in which it is possible to study selected plant/insect interaction in a controlled environment. Due to a combination of "direct" and "indirect" effects of CO2 enrichment on plant photosynthesis and plant development, canopy productivity is generally increased. In this paper, we discuss the effects of daytime and nighttime CO2 enrichment protocols on gas exchange of pepper plants (Capsicum annuum L, cv Cubico) grown in controlled environments. In addition, we present the effects of thrips, a common Insect pest, on the photosynthetic and respiratory activity of these plant canopies. Carbon dioxide has diverse effects on the physiology and mortality of insects. However, our data indicate that thrips and whiteflies, at least, are not killed "directly" by CO2 levels used to enhance photosynthesis and plant growth. Together the data suggest that the insect population is affected "indirectly" by CO2 and that the primary effect of CO2 is via its effects on plant metabolism.

Animals↗
PubMed1980

Environment for poultry.

The design of controlled environment systems for poultry is discussed. The requirements are reviewed by considering the responses of the birds to environmental factors and some practical methods of achieving the responses are described.

Animals↗
PubMed1996

Effect of CO2 levels on nutrient content of lettuce and radish.

Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar 'Waldmann's Green' and radish (Raphanus sativus L.) cultivar 'Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO2 level.

Atmosphere↗
PubMed2006

Growing environment and nutrient availability affect the content of some phenolic compounds in Echinacea purpurea and Echinacea angustifolia.

Medicinal plant production is different from other agricultural production systems in that the plants are grown for the production of specific phytochemical(s) for human use. To address this need, a Good Manufacturing Practice (GMP)-compliant, controlled-environment production system was developed for production of Echinacea purpurea and Echinacea angustifolia. Within the prototype facility, the growing systems, nutrient availability, water and physical environment were highly controlled. The current study was designed to evaluate the effects of different hydroponic systems, nutrient solution NO (3)(-)/NH (4)(+) ratios and mild water stress on the content of some phenolic compounds in Echinacea plants. The deep-flow solution culture system in which the plant roots were continuously immersed in the nutrient solutions was optimum for the growth of E. purpurea. Higher concentrations of caftaric acid, cynarin and echinacoside were produced in E. angustifolia plants grown in the soil-based growing media while the plants grown in the deep-flow solution system had higher levels of cichoric acid. Altering the NO (3)(-)/NH (4)(+) ratio or limited water stress did not have any significant effect on the phytochemical content of Echinacea plants. Echinacea plants grown in the controlled environment systems had higher or similar amounts of cynarin, caftaric acid, echinacoside and cichoric acid as previously reported in the literature for both field-cultivated and wild-harvested Echinacea plants. This growing system offers the advantages of year-round crop production with minimal contamination by environmental pollutants and common microbes.

Echinacea↗
PubMed1993

Determinants of oesophageal 'alkaline' pH environment in controls and patients with gastro-oesophageal reflux disease.

The determinants of the oesophageal alkaline pH environment are poorly understood. Saliva (pH 6.4-7.8) may be a major contributor, although some argue the importance of refluxed alkaline duodenal contents. Acid and alkaline reflux parameters were studied over 2 days in 30 subjects (control, oesophagitis and Barrett's patients; 10 each) using glass pH electrodes. In phase 1, one pH electrode was placed 1 cm below the upper oesophageal sphincter to assess the influence of saliva and the other 5 cm above the lower oesophageal sphincter. Phase 2 was identical except that one pH probe was 5 cm below the lower oesophageal sphincter to record duodenogastric reflux. Patient groups spent, on average, 50 fold more time during the upright and supine periods at acidic pH than controls. Saliva was responsible for the percentage of time the pH > 7 and contributed significantly to the percentage of time the pH > 6 in both the proximal and distal oesophagus of control subjects, as shown by an absence of pH > 7 and a significant (p < 0.001) fourfold decrease in pH > 6 during sleep. A similar pattern was seen in the proximal oesophagus of both reflux groups. The reflux and Barrett's patients, however did not show a significant decrease in the percentage of time the pH > 6 at night in the distal oesophagus suggesting a relative increase in 'alkaline' exposure from another source. This was not because of duodenogastric reflux as the corresponding pH rises in the fundus of the stomach were non-existent. Although this was not studied specifically, it is believed to be a protective meachanism, the result of alkaline secretion produced by submucosal oesophageal glands.

Adult↗
PubMed1980

The effect of prolonged light and dark adaptation on lens regeneration in the adult newt Triturus viridescens.

Light intensity has been shown to affect lens regeneration in adult newts. Experiments were designed to study the effects of different light controlled environments on lens regeneration in the newt T, viridescens. Animals were preadapted to three light conditions: control, light from below and dark for ninety (90) days prior to lentectomy. The newts remained in the controlled environments post-lentectomy to test the effects of light preadaptation on lens regeneration. The results indicate that controlled light sources from below cannot stimulate the ventral iris to regenerate a new lens or inhibit the dorsal iris from normal lens regeneration. Lens regeneration in preadapted dark animals is similar in rate and amount to the control group indicating a totally dark environment does not always inhibit lens regeneration.

Adaptation, Ocular↗
PubMed2003

Plant-centered biosystems in space environments: technological concepts for developing a plant genetic assessment and control system.

Plants will play an essential role in providing life support for any long-term space exploration or habitation. We are evaluating the feasibility of an adaptable system for measuring the response of plants to any unique space condition and optimizing plant performance under those conditions. The proposed system is based on a unique combination of systems including the rapid advances in the field of plant genomics, microarray technology for measuring gene expression, bioinformatics, gene pathways and networks, physiological measurements in controlled environments, and advances in automation and robotics. The resulting flexible module for monitoring and optimizing plant responses will be able to be inserted as a cassette into a variety of platforms and missions for either experimental or life support purposes. The results from future plant functional genomics projects have great potential to be applied to those plant species most likely to be used in space environments. Eventually, it will be possible to use the plant genetic assessment and control system to optimize the performance of any plant in any space environment. In addition to allowing the effective control of environmental parameters for enhanced plant productivity and other life support functions, the proposed module will also allow the selection or engineering of plants to thrive in specific space environments. The proposed project will advance human exploration of space in the near- and mid-term future on the International Space Station and free-flying satellites and in the far-term for longer duration missions and eventual space habitation.

Agriculture↗
PubMed2002

Modeling and control for closed environment plant production systems.

A computer program was developed to study multiple crop production and control in controlled environment plant production systems. The program simulates crop growth and development under nominal and off-nominal environments. Time-series crop models for wheat (Triticum aestivum), soybean (Glycine max), and white potato (Solanum tuberosum) are integrated with a model-based predictive controller. The controller evaluates and compensates for effects of environmental disturbances on crop production scheduling. The crop models consist of a set of nonlinear polynomial equations, six for each crop, developed using multivariate polynomial regression (MPR). Simulated data from DSSAT crop models, previously modified for crop production in controlled environments with hydroponics under elevated atmospheric carbon dioxide concentration, were used for the MPR fitting. The model-based predictive controller adjusts light intensity, air temperature, and carbon dioxide concentration set points in response to environmental perturbations. Control signals are determined from minimization of a cost function, which is based on the weighted control effort and squared-error between the system response and desired reference signal.

Algorithms↗
PubMed2004

Interactive effects of carbon dioxide, temperature, and ultraviolet-B radiation on soybean (Glycine max L.) flower and pollen morphology, pollen production, germination, and tube lengths.

Plant reproduction is highly vulnerable to global climate change components such as carbon dioxide concentration ([CO(2)]), temperature (T), and ultraviolet-B (UV-B) radiation. The objectives of this study were to determine the effects of season-long exposure to treatments of [CO(2)] at 360 (control) and 720 micromol mol(-1) (+CO(2)), temperature at 30/22 degrees C (control) and 38/30 degrees C (+T) and UV-B radiation 0 (control) and 10 kJ m(-2) d(-1) (+UV-B) on flower and pollen morphology, pollen production, germination, and tube lengths of six soybean genotypes (D 88-5320, D 90-9216, Stalwart III, PI 471938, DG 5630RR, and DP 4933RR) in sunlit, controlled environment chambers. The control treatment had 360 micromol mol(-1) [CO(2)] at 30/22 degrees C and 0 kJ UV-B. Plants grown either at +UV-B or +T, alone or in combination, produced smaller flowers with shorter standard petal and staminal column lengths. Flowers so produced had less pollen with poor pollen germination and shorter tube lengths. Pollen produced by the flowers of these plants appeared shrivelled without apertures and with disturbed exine ornamentation even at +CO(2) conditions. The damaging effects of +T and +UV-B were not ameliorated by +CO(2) conditions. Based on the total stress response index (TSRI), pooled individual component responses over all the treatments, the genotypes were classified as tolerant (DG 5630RR, D 88-5320: TSRI >-790), intermediate (D 90-9216, PI 471938: TSRI <-790 to >-1026), and sensitive (Stalwart III, DP 4933RR: TSRI <-1026). The differences in sensitivity identified among genotypes imply the options for selecting genotypes with tolerance to environmental stresses projected to occur in the future climates.

Carbon Dioxide↗
PubMed2007

Effect of moisture and pressure on tablet compaction studied with FTIR spectroscopic imaging.

FTIR spectroscopic imaging using a diamond ATR accessory has been applied to examine the influence of moisture and compression pressure on the density and components distribution of compacted pharmaceutical tablets. The model drug and excipient used within this study are ibuprofen and hydroxypropylmethylcellulose (HPMC). Chemical images of these compacted tablets were captured in situ without removing the tablet between measurements. A powder mixture of both, drug and excipient, prior to compaction, were subjected to a controlled environment, using a controlled humidity cell. Histograms were plotted to assess the density distribution quantitatively. This FTIR spectroscopic imaging approach enabled both measurement of water sorption and enhanced visualization of the density distribution of the compacted tablets.

Drug Stability↗
PubMed1992

Reinforcing and punishing consequences of kindling.

The motivational consequences of kindling were examined in the conditioned place preference paradigm. In a distinctive environment, rats received stimulation of the amygdala that triggered afterdischarge (AD) alone or AD and generalized seizures. After 4 conditioning trials, preference for the conditioning environment or a control environment was measured. Amygdaloid ADs associated with nonconvulsive seizures (stage 0) produced a conditioned decrease in time spent in the initially preferred chamber by rats receiving stimulation there, and they produced a conditioned increase in time spent in the initially nonpreferred chamber by rats receiving stimulation there. These effects were not large, in that there was no overall mean shift from preference to avoidance, or vice versa; but they were reliable and significant. Similarly, stage 5 seizures produced a small and nonsignificant decrease in time spent in the conditioning chamber in which seizures were triggered. It appears that amygdaloid AD produces weak effects that are either reinforcing or punishing, depending on the behavioral baseline, and that generalized amygdaloid seizures are, at most, mildly punishing.

Amygdala↗
PubMed1998

Effects of stress combinations on the expression of additive genetic variation for fecundity in Drosophila melanogaster.

To test whether stressful conditions altered levels of heritable variation in fecundity in Drosophila melanogaster, parent-offspring comparisons were undertaken across three generations for flies reared in a combined stress (ethanol, cold shock, low nutrition) environment or a control environment. The stressful conditions did not directly influence fecundity but did lead to a reduced fecundity in the offspring generations, perhaps reflecting cross-generation maternal effects. Both the heritability and evolvability estimates were higher in the combined stress treatment, reflecting an apparent increase in the additive genetic variance under stress. In contrast, there were no consistent changes in the environmental variance across environments.

Animal Nutritional Physiological Phenomena↗
PubMed1989

Identifying stimuli in the natural environment that control verbal responses.

When a learner is taught a new response, the stimuli that influence its display often are unknown. These stimuli alter the probability of occurrence of the response. That is, when they are present, the response occurs; when they are absent, it does not occur. By identifying the stimuli that influence the probability of newly acquired responses, interventionists may program for their generalization more effectively and efficiently. In the present study, 2 students who were moderately retarded were taught to label a coin. Eight environmental stimuli that were present during training were identified. The effect of each stimulus on the occurrence of the response was assessed prior to and after training by presenting the remaining seven stimuli and altering only the target stimulus. The results demonstrated that by altering one stimulus at a time, responding continued uninterrupted. For 1 of the 2 learners, however, responding was disrupted by altering two stimuli simultaneously. The implications of these findings are discussed in terms of stimulus control and generalization.

Child↗