Short-duration Experiments Research Articles

Biopyribole evolution during tremolite synthesis from dolomite and quartz in CO2-H2O fluid

A series of experiments with and without sample retreatment was performed on a starting mixture of dolomite plus quartz at 0.5 GPa and 600 °C in a CO 2 -H 2 O fluid with a mole fraction of CO 2 of 0.2 for durations up to 582 h. The initial reaction of dolomite and quartz led to rapid formation of talc and calcite instead of tremolite and calcite by the intended reaction: 5 dolomite + 8 quartz + H 2 O = tremolite + 3 calcite + 7 CO 2 . With continued treatment, the talc + calcite + quartz assemblage gradually reacts to form increasing amounts of tremolite and diopside with the eventual loss of quartz and nearly complete loss of talc. The detailed structure of the amphibole and the nature of the Mg enrichment were revealed using AEM analysis of individual amphibole crystals. The most abundant defects are triple-chain chain multiplicity faults (CMFs), which appear as isolated lamellae with single periodicity in short-duration experiments and increasingly as groups of lamellae with variable multiplicity and periodicity in longer duration experiments and especially in a long-duration experiment without retreatment. In this latter experiment, a calcian clinojimthompsonite domain extending 15 unit cells along the b axis was observed. The sample after 582 h and five retreatments shows, on average, 3.5% true solid solution with Mg expressed as the Mg-cummingtonite (MC) component after correction for the presence of CMFs. This sample is thought to most closely approach the equilibrium composition for the amphibole. The sample after 250 h with three retreatments has about 10%, whereas that after 582 h without retreatment has 0.6% MC component, the latter having a relatively high density of CMFs. This study affirms the importance that precursor non-amphibole biopyriboles play in the formation of tremolitic amphibole.

Controlled random search technique for estimation of convective heat transfer coefficient

This paper is concerned with a method for solving inverse heat conduction problem. The method is based on the controlled random search (CRS) technique in conjunction with modified Newton–Raphson method. The random search procedure does not need the computation of derivative of the function to be evaluated. Therefore, it is independent of the calculation of the sensitivity coefficient for nonlinear parameter estimation. The algorithm does not depend on the future-temperature information and can predict convective heat transfer coefficient with random errors in the input temperature data. The technique is first validated against an analytical solution of heat conduction equation for a typical rocket nozzle. Comparison with an earlier analysis of inverse heat conduction problem of a similar experiment shows that the present method provides solutions, which are fully consistent with the earlier results. Once validated, the technique is used to investigate another estimation of heat transfer coefficient for an experiment of short duration, high heating rate, and employing indepth temperature measurement. The CRS procedure, in conjunction with modified Newton–Raphson method, is quite useful in estimating the value of the convective heat-transfer coefficient from the measured transient temperature data on the outer surface or imbedded thermocouple inside the rocket nozzle. Some practical examples are illustrated, which demonstrate the stability and accuracy of the method to predict the surface heat flux.

Dynamic Range of Mass Accuracy in LTQ Orbitrap Hybrid Mass Spectrometer

Using a novel orbitrap mass spectrometer, the authors investigate the dynamic range over which accurate masses can be determined (extent of mass accuracy) for short duration experiments typical for LC/MS. A linear ion trap is used to selectively fill an intermediate ion storage device (C-trap) with ions of interest, following which the ensemble of ions is injected into an orbitrap mass analyzer and analyzed using image current detection and fast Fourier transformation. Using this technique, it is possible to generate ion populations with intraspectrum intensity ranges up to 10(4). All measurements (including ion accumulation and image current detection) were performed in less than 1 s at a resolving power of 30,000. It was shown that 5-ppm mass accuracy of the orbitrap mass analyzer is reached with >95% probability at a dynamic range of more than 5000, which is at least an order of magnitude higher than typical values for time-of-flight instruments. Due to the high resolving power of the orbitrap, accurate mass of an ion could be determined when the signal was reliably distinguished from noise (S/Np-p)>2...3).

GROWTH RATE AND THERMAL TOLERANCE OF TWO ENDANGERED SNAKE RIVER SNAILS

We investigated the temperature tolerance and growth of 2 federally protected freshwater gastropods from southern Idaho: Valvata utahensis and Pyrgulopsis idahoensis. Snails were collected in the Snake River and transported to the laboratory where they were kept under highly controlled conditions. In varying-temperature, short-duration experiments, the temperatures tolerated by both species were between 7°C and 34°C. In constant-temperature, long-duration experiments, growth rates were between 0.004 mm · d−1 and 0.016 mm · d−1, and we created growth curves for both species that were previously lacking. Our results are among the first to report temperature tolerances and growth rates of native Snake River snails, and we discuss implications for the biology and management of both species.

N-fertilizer saving by the inoculation of Gluconacetobacter diazotrophicus and Herbaspirillum sp. in micropropagated sugarcane plants

Colonization of micropropagated sugarcane plants by Gluconacetobacter diazotrophicus and Herbaspirillum sp. was confirmed by a dot-immunoblot assay. In all, a 45-day short-term and 180-day long-term experiments conducted on micropropagated sugarcane plants of Co 86032, a sugar rich popular variety in South India, indicated the usefulness of these diazotrophs as plant growth promoting bacteria. Co-inoculation of these two bacteria enhanced the biomass considerably under N-limited condition in the short duration experiment. In the long-term experiment, the establishment of inoculated Herbaspirillum sp. remained stable with the age of the crop up to 180 days, while there was a reduction in population of G. diazotrophicus for the same period. The total bio-mass and leaf N were higher in plants inoculated with G. diazotrophicus and Herbaspirillum sp. without N fertilization and also in plants with 50% of the recommended N (140 kg ha(-1)) than the plants fertilized with recommended dose of inorganic N (280 kg ha(-1)). This experiment showed that inoculation with these bacteria in sugarcane variety Co 86032 could mitigate fertilizer N application considerably in sugarcane cultivation.

Are habitat-tracking metacommunities dispersal limited? Inferences from abundance-occupancy patterns of epiphylls in Amazonian forest fragments

In theory, habitat fragmentation alters plant community dynamics by influencing both local (within patch) and regional (among patch) processes. However, the lengthy generation times of plant taxa relative to the short duration of most experiments has precluded studies from assessing the impact of fragmentation at both local and regional scales. Due to their accelerated life cycles, high rates of local extinction, and naturally patchy substrates, epiphyllous bryophyte assemblages are an appropriate plant guild for empirically testing metacommunity-based predictions associated with habitat fragmentation. By examining the local abundance and regional distribution patterns of 67 epiphyllous (leaf-inhabiting) bryophyte species in an experimentally fragmented landscape in Amazonia, we demonstrate that changes in local abundance wrought by habitat fragmentation are best explained by fragment size rather than proximity to forest edge. Furthermore, evidence of a simultaneous inter-specific decline in epiphyll local abundance and regional distribution in small (1- and 10-ha) forest fragments corroborate with metapopulation-based predictions highlighting the importance of immigration in buffering from patch extinction risk (i.e., the rescue effect). Collectively, these results provide indirect evidence that dispersal limitation, rather than compromised habitat quality attributable to edge effects, likely account for species loss from small tropical forest fragments. Whether dispersal limitation is due to increased insularity from regional sources for epiphyll recolonization or rather to lowered within-fragment dispersal potential is unknown; nonetheless, the long-term persistence of these microscopic plant metacommunities depends on the preservation of rain forest reserves of at least 100-ha in size.

Application of atomic force microscopy and scaling analysis of images to predict the effect of current density, temperature and leveling agent on the morphology of electrolytically produced copper

Atomic force microscopy (AFM) was used to study the morphology of electrodeposited Cu at current densities from 183 to 253 A m −2. Digital image analysis was employed to parameterize the morphological information encoded in AFM images and to extract information concerning the mechanism of the electrodeposition reaction. It has been shown how the limiting roughness, δ, the critical scaling length, L c and the aspect ratio, 4 δ/ L c, vary as a function of the deposition time and electrodeposition conditions, such as temperature, current density and the amount of organic additives. It has been demonstrated how laboratory experiments of short duration and the scaling analysis of AFM images can be used to predict roughness of the metal sample after 2 weeks of industrial electrorefining.

Purification of human erythrocyte glucose 6-phosphate dehydrogenase and glutathione reductase enzymes using 2 ′,5 ′-ADP Sepharose 4B affinity column material in single chromatographic step

The enzymes of glucose 6-phosphate dehydrogenase and glutathione reductase were purified from human erythrocytes in one chromatographic step consisting of the use of the commercially available resin 2 ′,5 ′-ADP Sepharose 4B by using different washing buffers. Ammonium sulfate (30–70%) precipitation was performed on the hemolysate before applying to the affinity column. Using this procedure, G6PG, having the specific activity of 22.9 EU/mg proteins, was purified with a yield of 43% and 9150-fold; GR, having the specific activity of 20.7 EU/mg proteins, was purified with a yield of 26% and 8600-fold. The purity of the enzymes was checked on sodium dodecyl sulfate–polyacrylamide gel electrophoresis and each purified enzyme showed a single band on the gel. This procedure has advantages of preventing of enzyme denaturation, short experimental duration, and use of less chemical materials for purification of the enzymes.

A Simplified Falling‐Head Technique for Rapid Determination of Field‐Saturated Hydraulic Conductivity

Simplified measurements of the field‐saturated hydraulic conductivity, Kfs, require short duration experiments, small water volumes, and easily transportable equipment. A simplified falling‐head (SFH) technique for the rapid determination of Kfs has been developed and tested. The technique consists in applying a small volume of water on a soil surface, confined by a ring inserted a short distance into the soil, and then measuring the time from the application of water to the instant at which the surface area is no longer covered by water. A measurement of the initial and field‐saturated soil water contents, and an estimate of the α* parameter of the Gardner's exponential model are then used to calculate Kfs using a simple solution that includes gravity. The Kfs of both repacked and undisturbed soil cores was determined in the laboratory by the SFH and the early time constant‐head (ECH) techniques. The SFH and (constant‐head) pressure infiltrometer (PI) techniques were then compared in the field. The maximum discrepancy between the mean Kfs results obtained within an experiment was of a factor of approximately two. This difference is negligible in most practical applications and it was concluded that the SFH technique compared favorably with the ECH technique in the laboratory and to the PI technique in the field. The SFH technique appears promising for determining Kfs in a relatively short period of time without the need for extensive instrumentation or analytical methodology, and therefore it appears suitable for detailed field measurements over large areas.

A Simplified Falling-Head Technique for Rapid Determination of Field-Saturated Hydraulic Conductivity

Simplified measurements of the field-saturated hydraulic conductivity, Kfs, require short duration experiments, small water volumes, and easily transportable equipment. A simplified falling-head (SFH) technique for the rapid determination of Kfs has been developed and tested. The technique consists in applying a small volume of water on a soil surface, confined by a ring inserted a short distance into the soil, and then measuring the time from the application of water to the instant at which the surface area is no longer covered by water. A measurement of the initial and field-saturated soil water contents, and an estimate of the α* parameter of the Gardner's exponential model are then used to calculate Kfs using a simple solution that includes gravity. The Kfs of both repacked and undisturbed soil cores was determined in the laboratory by the SFH and the early time constant-head (ECH) techniques. The SFH and (constant-head) pressure infiltrometer (PI) techniques were then compared in the field. The maximum discrepancy between the mean Kfs results obtained within an experiment was of a factor of approximately two. This difference is negligible in most practical applications and it was concluded that the SFH technique compared favorably with the ECH technique in the laboratory and to the PI technique in the field. The SFH technique appears promising for determining Kfs in a relatively short period of time without the need for extensive instrumentation or analytical methodology, and therefore it appears suitable for detailed field measurements over large areas.

Chlorination of dibenzofuran and dibenzo- p-dioxin vapor by copper (II) chloride

Dibenzofuran (DF) is formed from phenol and benzene in combustion gas exhaust streams prior to particle collection equipment. Subsequent chlorination at lower temperatures on particle surfaces is a potential source of chlorinated dibenzofuran (CDF). Gas streams containing 8% O 2 and approximately 0.1% DF vapor were passed through particle beds containing copper (II) chloride (0.5% Cu, mass) at temperatures ranging from 200 to 400 °C to investigate the potential for CDF formation during particle collection. Experiment duration was sufficient to provide an excess amount of DF (DF/Cu=3). The efficiency of DF chlorination by CuCl 2 and the distribution of CDF products were measured, with effects of temperature, gas velocity, and experiment duration assessed. Results of a more limited investigation of dibenzo- p-dioxin (DD) chlorination by CuCl 2 to form chlorinated DD (CDD) products are also presented. The efficiency of DF/DD chlorination by CuCl 2 was high, both in terms of CuCl 2 utilization and DF/DD conversion. Total yields of Cl on CDF/CDD products of up to 0.5 mole Cl per mole CuCl 2 were observed between 200 and 300 °C; this suggests that nearly 100% CuCl 2 was utilized, assuming a conversion of two moles of CuCl 2 to CuCl per mole Cl added to DD/DF. In a short duration experiment (DF/Cu=0.3), nearly 100% DF adsorption and conversion to CDF was achieved. The degree of CDF chlorination was strongly dependent on gas velocity. At high gas velocity, corresponding to a gas–particle contact time of 0.3 s, mono-CDF (MCDF) yield was largest, with yields decreasing with increasing CDF chlorination. At low gas velocity, corresponding to a gas–particle contact time of 5 s, octa-CDF yield was largest. DF/DD chlorination was strongly favored at lateral sites, with the predominant CDF/CDD isomers within each homologue group those containing Cl substituents at only the 2,3,7,8 positions. At the higher temperatures and lower gas velocities studied, however, broader isomer distributions, particularly of the less CDD/CDF products, were observed, likely due to preferential destruction of the 2,3,7,8 congeners.

RAPID LABORATORY EVOLUTION OF ADULT WING AREA IN DROSOPHILA MELANOGASTER IN RESPONSE TO HUMIDITY

We examined the evolutionary response of wing area (a trait highly correlated with other measures of body size) to relative humidity (RH), temperature, and their interaction in Drosophila melanogaster, using replicated lines that had been allowed to evolve at low or high humidity at 18°C or at 25°C. We found that after 20 weeks of selection (5–10 generations), low RH lines had significantly greater wing areas than high RH lines in both sexes. This evolutionary response may have resulted from selection of larger flies with a smaller surface area for water loss relative to their weight, or as a correlated response to selection on some other unidentified trait. There were no evolutionary effects of temperature on wing area or cell density. This may have been due to the short duration of the selection experiment, and/or counteracting selection pressures on body size at warm temperature.

A new approach to modelling streamflow reductions resulting from commercial afforestation in South Africa

Synopsis The Department of Water Mfairs and Forestry has, for some time, needed a comprehensive tool to incorporate the impacts of commercial afforestation on water resources into water use authorisation and allocation processes. Simulation modelling on a national scale, using the ACRU model, was identified as one possible solution. However, in order to establish confidence in the national simulation results, it was necessary to first verify model output against reliable observed data from process studies and long-term catchment afforestation experiments. In the verification phase, long term reductions in streamflow resulting from afforestation were satisfactorily simulated for five research catchments. Some problems were experienced with catchments in the Western Cape, with verifications on shorter duration experiments and the simulation of specific evaporative processes. Modelling oflow flows was less successful than for total flows. In the second phase (the generation of the national database), simulat...

Parametric images of the extrastriatal D2 receptor density obtained using a high-affinity ligand (FLB 457) and a double-saturation method.

The potential of positron emission tomography for the quantitative estimation of receptor concentration in extrastriatal regions has been limited in the past because of the low density of the D2 receptor sites in these regions and the insufficient affinity of the most widely used radioligands for dopamine receptors. The new method described in this paper permits the estimate of the D2 receptor concentration in the extrastriatal regions using a two-injection protocol and FLB 457, a ligand with a high affinity (20 pmol/L in vitro ) with D2 dopamine receptors. This approach is not valid for the striatal regions because some hypotheses cannot be verified (because of the high receptor concentration in these regions). The experimental protocol includes two injections with ligand doses designed to significantly occupy the extrastriatal receptor sites (approximately 90%), while leaving less than 60% of the receptor sites occupied by the ligand in the striatal regions. The results obtained using this double-saturation method are in line with the concentration estimates previously obtained using the multiinjection approach. The receptor concentration is 2.9 +/- 0.5 pmol/mL in the thalamus, 1.0 +/- 0.2 pmol/mL in the temporal cortex, and 0.35 +/- 0.13 pmol/mL in the occipital cortex. This study provides new arguments supporting the presence of a small receptor-site concentration in the cerebellum, estimated at 0.35 +/- 0.16 pmol/mL The simplicity of the calculation used to estimate the receptor concentration lends itself easily to parametric imaging. The receptor concentration is estimated pixel by pixel, without filtering. This method permits estimation of the extrastriatal D2 receptor concentration using an experimental protocol that can easily be used in patient studies (i.e., single experiment, no blood sampling, short experiment duration).

Gravity independence of seed-to-seed cycling in Brassica rapa.

Growth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing, and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times 13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity.

Partial Replacement of Forage with Nonforage Fiber Sources in Lactating Cow Diets. I. Performance and Health

Seventy-eight Holsteins were fed for 112 d to evaluate performance and health responses to diets varying in source and concentration of fiber. Three diets based on different carbohydrate feeding strategies were formulated. These diets contained low concentrations of forage and neutral detergent fiber (NDF) (12.6% forage NDF, 19.5% total NDF), adequate NDF and forage (20% forage NDF, 24.8% total NDF), or low forage with additional NDF from cereal byproducts (12.7% forage NDF, 33.4% total NDF). Responses to sodium bicarbonate supplementation (0 or 0.8% of diet DM) were evaluated for each carbohydrate strategy, and bicarbonate improved performance on all diets. Eight cows were used concurrently in a Latin square experiment to evaluate the linearity of milk fat concentration response to increasing concentrations of byproduct NDF in low-forage diets. Considering both trials, cereal byproduct NDF was only 27% as effective as NDF from alfalfa silage in eliciting a milk fat concentration response, which was less than predicted from previous experiments. This difference was not because of the short duration of previous experiments nor because of nonlinearity in the response to byproduct NDF. Low-forage diets fed for 112 d did not result in major health disorders for midlactation cows. However, several indicators suggested that cows fed low-forage, high-NDF diets might be less susceptible to ruminal acidosis than those fed diets containing low forage and low NDF, especially during times of dietary transition. Although the effective fiber value in various feeds is variable and difficult to quantify, the value of byproduct fiber needs to be considered when balancing the carbohydrate fraction of dairy rations.

Picosecond time-resolved electronic spectroscopy in plate impact shock experiments: Experimental development

An experimental method was developed to perform picosecond time-resolved electronic spectroscopy in single-event, plate impact, shock wave experiments. Several experimental difficulties had to be addressed due to the fast time resolution (100 ps) and short time duration (12.7 ns) of such experiments. Procedures are described to address the following experimental issues: (i) synchronization of the light source, detection equipment, and the shock event within the experimental duration, (ii) incorporation of a Nd:YAG laser (operative in a repetitive mode) into the experimental configuration, and (iii) sources of temporal dispersion. Representative results are shown from experiments performed on single crystal CdS. The developments described here are also expected to be useful for shock wave experiments involving Raman, fluorescence, or other types of spectroscopy which require the use of a laser.

Reactive isothermal solidification in the Ni–Sn system

The kinetics, morphologies, and mechanisms involved in Reactive Isothermal Solidification were investigated. Experiments involved the Ni–Sn binary system. Three types of samples were prepared: powder samples, samples for dipping experiments, and model multi-layer samples. The samples were heat treated for different durations at temperatures in the range 235–600°C. The following results were obtained. During solidification, Ni 3Sn 4 was the only phase detected by SEM, optical microscopy, and XRD. However, in electron diffraction during TEM examination, the Ni 3Sn phase was also found. When solidification was complete, the other two equilibrium intermediate phases were detected by SEM and XRD. The Ni 3Sn 4 grew mainly as a layer at the solid/liquid interface. The Ni 3Sn 4/liquid interface was not flat, containing deep grain boundary grooves, and part of the layer had crumbled into the liquid. As the Ni 3Sn 4 layer grows, lateral grain growth occurs. The time-dependence of the mean grain size obeys a parabolic law. In short-duration experiments, the growth kinetics of the Ni 3Sn 4 layer, too, was found to be parabolic, and with an activation energy of 27.6±1.7 kJ/mol. This value corresponds to the activation energy for the diffusion of Ni in liquid Sn. In long-time experiments deceleration of the growth kinetics was observed. Simultaneously with the phase growth and the lateral grain growth the coarse Ni 3Sn 4 layer grains crumble into the liquid, a process related to the grooving of the Ni 3Sn 4 layer which takes place at the microstructural transition zone (MTZ). The crumbling as well as the lateral grain growth are considered to be the factors that affect the growth kinetics.

UPTAKE AND RELEASE KINETICS OF COPPER BY THE AQUATIC MOSS Fontinalis antipyretica

Copper uptake and release rates by Fontinalis antipyretica were investigated. A contamination stage in which the plants were exposed to Cu concentrations in the range 0.09–0.75 mg l −1 was followed by a decontamination period, exposing the plants to metal-free water. Tanks were operated in perfectly mixed conditions and the illumination at water surface was 740 lux. Short and long duration experiments (217 and 1008 h, respectively) were carried out with plants collected in May and August, respectively. A simple mass transfer model was fitted to the experimental results in order to determine the uptake and release rate constants, k 1 and k 2, the Cu concentration at the end of the uptake phase, C mu, and the equilibrium concentrations, C me and C mr, for the contamination and decontamination stages, respectively. In the short duration experiment, k 1 decreased from 846 to 628 h −1 as Cu concentration increased from 0.14 to 0.60 mg l −1. In the long duration one, with plants in different physiological conditions, k 1 decreased from 448 to 293 h −1 as Cu concentration increased from 0.09 to 0.75 mg l −1. The release rate constant, k 2, appears not to depend on the Cu concentration and averaged 0.020 and 0.011 h −1 in the first and second experiments, respectively. The ratio k 1/k 2 represents a bioconcentration factor, BCF (Cu concentration in the plant, dry wt/Cu concentration in the water). BCF values ranged between 40,000 and 30,000. A biological elimination factor BEF=1− C mr C mu was also calculated. BEF values slightly increased with C mu, varying from 0.58 to 0.62 (5203<C mu <15762 mg kg −1 dry wt.) and from 0.46 to 0.66 (3127<C mu <23773 mg kg −1 dry wt.) in the short and long duration experiments, respectively.

Changes inArabidopsisLeaf Ultrastructure, Chlorophyll and Carbohydrate Content During Spaceflight Depend on Ventilation

Leaf structure and function under spaceflight conditions have received little study despite their important implications for biological life support systems using plants. Previous reports described disruption of the membrane apparatus for photosynthesis and a general decrease in carbohydrate content in foliage. During a series of three short-duration experiments (Chromex-03, -04, -05) on the US space shuttle (STS-54, STS-51, STS-68), we examinedArabidopsis thalianaleaves. The plants were at the rosette stage at the time of loading onto the space shuttle, and received the same light, temperature, carbon dioxide and humidity regimes in the orbiter as in ground controls. The experiments differed according to the regime provided in the headspace around the plants: this was either sealed (on mission STS-54); sealed with high levels of carbon dioxide (on mission STS-51) or vented to the cabin air through a filtration system (on mission STS-68). Immediately post-flight, leaf materials were fixed for microscopy or frozen in liquid nitrogen for subsequent analyses of chlorophyll and foliar carbohydrates. At the ultrastructural level, no aberrations in membrane structure were observed in any of the experiments. When air-flow was provided, plastids developed large starch grains in both spaceflight and ground controls. In the experiments with sealed chambers, spaceflight plants differed from ground controls with regard to measured concentrations of carbohydrate and chlorophyll, but the addition of airflow eliminated these differences. The results point to the crucial importance of consideration of the foliage micro-environment when spaceflight effects on leaf structure and metabolism are studied.