Average Number Of Pores Research Articles

Eggs of leach's storm petrel: O 2 Uptake, water loss, and microclimate of the nest

1. 1. The O 2 consumption and water loss of eggs of Leach's storm petrel ( Oceanodroma leucorhoa) were measured during their natural incubation on Kent Island, Bay of Fundy, New Brunswick, Canada. 2. 2. During their 42-day incubation period, the 10.5 g eggs had a total O 2 consumption of 1.81 and the O 2 uptake at the pre-internal pipping stage was estimated at 100 ml/day. 3. 3. The rate of water loss was followed over a 21-day period, averaging 47mg/day, and for the total incubation period predicts a total diffusive water loss of 1.96g. 4. 4. Egg temperatures and burrow temperatures were 33.4 and 8.3°C, respectively, resulting in an egg-nest water vapor pressure difference of 30.7 Torr, which when multiplied by the water vapor conductance of the shell, 1.55mg/day Torr, accounts for the observed daily water loss. 5. 5. The average number of pores per egg was 1516, SD 274.

Distribution of pores within alveoli in the human lung.

Usually the wall opposite the orifice of alveoli has been used to study interalveolar pores by scanning electron microscopy. To ascertain whether biased results may be obtained from this, the distribution of pores within alveoli was studied in human lungs. By the use of scanning electron photomicrographs, the number, major axes of pores, and proportional area of pores to the alveolar wall were estimated. The alveolar wall seen opposite the orifice was defined as the bottom wall. Average number of pores per alveolus was 13-21, and one-half of them was located in the bottom walls. The average length of major axes was 7-19 micron, and average area fractions were 0.8-5%. The distribution of the numerical density, area fraction, and size of pores was uniform regardless of their location within the alveolus and the size of alveoli. Thus pores can be compared using the bottom walls of alveoli. This will facilitate the study of the effects of age, smoking, and topography on pore size and frequency in humans.

Electrokinetic studies of the testosterone-aqueous d-glucose interface

Electro-osmosis and streaming-potential measurements were made across a testosterone-plug membrane, using water and aqueous solutions of d-glucose as permeants. The electrophoretic velocity of testosterone particles dispersed in these solutions was also measured, experiments being confined to the range where linear flux-force relationships hold. Phenomenological coefficients were evaluated by using these linear relations, and the results analyzed inthe light of the thermodynamics of irreversible processes. Saxen's relationship holds between electro-osmosis and streaming potential. Concentration dependence of the various phenomenological coefficients was also examined. Cross-phenomenological coefficients were found to decrease with increase in the concentration of d-glucose solutions. The results are explained on the basis of strong hydrogen-bonding between d-glucose and the surrounding water molecules. Such membrane parameters as pore size, average number of pores, and the membrane constant were evaluated. Electro-osmotic and electrophoretic data were used to estimate the zeta potential, in order to characterize the membrane-permeant interface. The dependence of the zeta potential on the concentration was also examined.

A new high Hcgamma ferric oxide exhibiting coercive force as high as 450-470 Oe

The basic properties of a new high H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> gamma ferric oxide (γ-HY) exhibiting coercive force as high as 450 ∼ 470 Oe were compared with those of conventional gamma ferric oxide (γ-LOP). The average axial ratio was 9 : 1 and the average number of pores was 0.2 per one particle for γ-HY. The pigment volume concentration was 15% increased and the gloss of tape surface 25% improved for γ-HY in the same tape formulation. The squareness ratio was 8% larger and the switching field distribution 25% narrower for γ-HY. The improved dispersibility and orientability were directly observed from the scanning electron micrograph for γ-HY tape.

The dimensions and number of pit membrane pores in conifer wood

A method is described which allows the determination of the average size, and the average number pertracheid, of the pit membrane pores through which fluids can pass in the longitudinal direction along oven-dried conifer wood. This consists in the observation of flow rates through the wood, in turn, of a non-polar liquid (n-hexane) and of a gas (air) at low pressure. Preliminary tests with Millipore filters of known porosity show that the method is sufficiently reliable to give pore sizes with acceptable accuracy, and reasons are given to expect the flow equations derived to be applicable to flow through wood. For all species examined the radii of the pores are larger for sap wood than for heartwood. They vary with species, ranging from 0.34µm (Larix leptolepis, heartwood) to (exceptionally among the species examined) 2.75µm (L. leptolepissapwood) with an average of about 0.8µm. The average number of pores per tracheid varies with species but is always of the order of unity. This is lower than was expected; it is, however, in harmony with other recent work and indicates a widespread aspiration of pits during drying. The precise meaning of the average pore size determined by the present methods depends on the distribution of pore sizes in a specimen and this is examined. The method used makes the assumption implicit in all previous work, that the resistance to flow resides entirely in the pit membrane. It is shown that, if the figure of unity means literally that each tracheid in a specimen possesses one open spore, this assumption is valid. If, however, only a few tracheids are available for flow, with correspondingly a greater number of open pores pertracheid, then this assumption cannot be accepted. Further work is necessary to determine the number of tracheids involved. /