Permeability sentence example

permeability
  • The first exact experiments demonstrating the changes which occur in the permeability of iron,, 3 Phil.
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  • In regard to water, all soils have two actions - namely, permeability and absorbability.
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  • So far, the best results have been attained with aluminium, and the permeability was greatest when the percentages of manganese and aluminium were approximately proportional to the atomic weights of the two metals.
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  • The values of the permeability corresponding to the highest and lowest temperatures are given in the following table.
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  • The silicon-iron had, in fields up to about Io, a greater permeability than a sample of the best Swedish charcoal-iron, and its hysteresisloss for max.
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  • Equations (33) and (34) show that when, as is generally the case with ferromagnetic substances, the value of is considerable, the resultant magnetic force is only a small fraction of the external force, while the numerical value of the induction is approximately three times that of the external force, and nearly independent of the permeability.
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  • Low hysteresis is the chief requisite for iron which is to be used for transformer cores, and it does not necessarily accompany high permeability.
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  • This was followed at the close of the same year by the discovery of the magnetic condition of all matter, a discovery which initiated a prolonged and fruitful study of paramagnetic and diamagnetic phenomena, including magnecrystallic action and " magnetic conducting power," now known as permeability.
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  • Owing, however, to the very variable permeability of the strata, the tributaries of the Thames, when separately gauged in dry seasons, yield the most divergent results.
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  • Imagine for a moment that the sand grains were by any means rendered immobile without change in the permeability of their interspaces; we could then dispense with the iron or brickwork lining of the well; but as there would still be no cracks or fissures to extend the area of percolating water exposed to the open well, the yield would be very small.
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  • The areas of research are listed below Increased epithelial permeability in airways is known to be associated with the hyperactivity of the asthmatic airway.
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  • They show varying permeability to a range of monovalent and divalent cations.
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  • This type of arrangement is found in the kidney glomerulus, where the basal lamina acts as a permeability barrier or sieve.
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  • The permeability of the tomato epidermal peels to the exogenous chemicals was tested and found to be adequate.
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  • New sensors will include a cone penetrometer (CPT ), permeability probe and a resistivity probe.
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  • Nystatin however, binds to ergosterol and alters membrane permeability and hence allows leakage of intracellular contents.
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  • Exudate - the fluid plasma which leaks out of blood vessels due to an increase in capillary permeability.
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  • These molecules induce smooth muscle contraction and enhance vascular permeability.
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  • To identify the effect of IL-6 on intestinal permeability.
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  • Ni Resist can exhibit low levels of magnetic permeability i.e. they can be non magnetic.
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  • The models include trapping of gas and reduction of water relative permeability in the presence of trapped gas.
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  • Mr Shattock believes that low levels of IAG may be caused by increased gut permeability resulting from the presence of measles virus.
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  • Also, water vapor permeability is important for certain products.
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  • It all depends on the oxygen permeability of plastic water bottles.
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  • For example, to establish the fracture history or fault zone permeability.
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  • These artificial composites exhibit the unusual left-handedness, i.e. simultaneously negative permittivity and negative permeability.
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  • In basement reservoirs matrix porosity is effectively close to zero and most of the storage capacity and permeability is due to fractures.
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  • Ewing has also studied the effect of vibration in conferring upon iron an apparent or spurious permeability of high value; this effort also is most conspicuous when the magnetizing force is weak.
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  • The members of the first class influence the endothelial plates of the capillaries injuriously, inducing thereby increased permeability; those of the second class (sugar, &c.), on injection into the blood, attract water from the tissues and cause a condition of hydraemic plethora with increased capillary pressure.
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  • High vapor permeability allows any moisture collected by the sheets to dry out naturally.
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  • Some patients also suffer loss of protein from the body that often results in low blood levels of albumin and total protein (protein-losing enteropathy) due to increased GI tract permeability.
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  • Its physical properties, permeability by water, extensibility and elasticity, receive their interpretation in the needs of the latter.
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  • The peculiarity of the protoplasm in almost every cell is that it is especially active in the regulation of its permeability by water.
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  • The response to the stimulus takes the form of increasing the permeability of particular cells of the growing structures, and so modifying the degree of the turgidity that is the precursor of growth in them.
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  • The extent of the area affected and of the variation in the turgor depends upon many circumstances, but we have no doubt that in the process of modifying its own permeability by some molecular change we have the counterpart of muscular contractibility.
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  • Thus the scenery of a limestone country depends on the solubility and permeability of the rocks, leading to the typical Karst-formations of caverns, swallowholes and underground stream courses, with the contingent phenomena of dry valleys and natural bridges.
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  • The permeability of most material substances differs very slightly from unity, being a little greater than I in paramagnetic and a little less in diamagnetic substances.
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  • In the case of the ferromagnetic metals and some of their alloys and compounds, the permeability has generally a much higher value.
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  • No substance has yet been discovered having a negative susceptibility sufficiently great to render the permeability (= I +471K) negative.
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  • The total magnetic induction or flux corresponds to the current of electricity (practically measured in amperes); the induction or flux density B to the density of the current (number of amperes to the square centimetre of section); the magnetic permeability to the specific electric conductivity; and the line integral of the magnetic force, sometimes called the magnetomotive force, to the electro-motive force in the circuit.
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  • If a hollow sphere 7 of which the outer radius is R and the inner radius r is placed in a uniform field Ho, the field inside will also be uniform and in the same direction as Ho, and its value will be approximately 3 i - R 3 For a cylinder placed with its axis at right angles to the lines of force, 2 = Ho (41) 2 +4(-2)(i - R2) These expressions show that the thicker the screen and the greater its permeability o, the more effectual will be the shielding action.
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  • The presence of ordinary impurities usually tends to diminish the permeability, though, as will appear later, the addition of small quantities of certain other substances is sometimes advantageous.
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  • When it is mechanically hardened by hammering, rolling or wire-drawing its permeability may be greatly diminished, especially under a moderate magnetizing force.
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  • An experiment by Ewing showed that by the operation of stretching an annealed iron wire beyond the limits of elasticity the permeability under a magnetizing force of about 3 units was reduced by as much as 75%.
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  • The permeability of a soft iron wire, which was tapped while subjected to a very small magnetizing force, rose to the enormous value of about 80,000 (Magnetic Induction, § 85).
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  • An excellent instrument of the class is Ewing's permeability bridge.
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  • If, however, the permeability of the test rod differs from that of the standard, the number of lines of induction flowing in opposite directions through the two rods will differ, and the excess will flow from one yoke to the other, partly through the air, and partly along the path provided by the bent bars, deflecting the compass needle.
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  • Steel behaves in a similar manner, but the maximum permeability is not so high as in iron, and the fall, when the critical point is approached, is less abrupt.
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  • Specimens of curves showing the relation of induction to magnetic field at various temperatures, and of permeability to temperature with fields of different intensities, are given in figs.
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  • They showed that the permeability of this sample of iron was considerably diminished at the lower temperature.
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  • Most of the permeability-temperature curves were more or less convex towards the axis of temperature, and in all the experiments except those with annealed iron and steel wire, the permeability was greatest at the lowest temperature.
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  • The permeability of cobalt, both annealed and unannealed, was always diminished at the low temperature.
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  • A sample of Hadfield's manufacture, containing 1 2.36% of manganese, differed hardly at all from a non-magnetic substance, its permeability being only 1.27.
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  • The permeability of the alloys containing from 1 to 4.7% of nickel, though less than that of good soft iron for magnetizing forces up to about 20 or 30, was greater for higher forces, the induction reached in a field of 240 being nearly 21,700.
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  • The induction for considerable forces was found to be greater in a steel containing 73% of nickel than in one with only 33%, though the permeability of pure nickel is much less than that of iron.
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  • The addition of silicon in small quantities considerably diminished permeability and increased coercive force; but when the proportion amounted to 2.5% the maximum permeability (µ =5100 for H =2) was greater than that of the nearly pure iron used for comparison, while the coercive force was only 0.9.
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  • The aluminium-iron attained its greatest permeability in a field of o 5, about that of the earth's force, when its value was 9000, this being more than twice the maximum permeability of the Swedish iron.
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  • When the proportion of aluminium to manganese was made a little greater or smaller, the permeability was diminished.
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  • Rowland,' whose careful experiments led to general recognition of the fact previously ignored by nearly all investigators, that magnetic susceptibility and permeability are by no means constants (at least in the case of the ferromagnetic metals) but functions of the magnetizing force.
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  • It varies with the increase of the intracapillary or decrease of the extracapillary pressure, and is also in part regulated by the greater or lesser permeability of the vessel-walls.
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  • Thus, while increased pressure in the blood or lymph vessels may be one factor, and increased permeability of the capillary endothelium another, increased osmotic pressure in the tissues and lymph is probably the most important in the production of dropsy.
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  • Permeability is practically identical with the speed at which percolation takes place; through clay it is slow, but increases in rapidity through marls, loams, limestones, chalks, coarse gravels and fine sands, reaching a maximum in soil saturated with moisture.
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  • On the other hand, the same observations go to show that the disease is met with oftener on the more recent formations than the older, and this fact, so far as concerns the physical characters of the soil, is identical with the questions of permeability to air and water.
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  • It has been variously attributed to metamorphism, consequent upon igneous intrusion, earth movements and other kinds of geothermic action, greater or less loss of volatile constituents during the period of coaly transformation, conditioned by differences of permeability in the enclosing rocks, which is greater for sandstones than for argillaceous strata, and other causes; but none of these appears to be applicable over more than limited areas.
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  • Coupling together these ideas he was finally enabled to prove that the propagation of electric and magnetic force takes place through space with a certain velocity determined by the dielectric constant and the magnetic permeability of the medium.
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  • If we imagine the current in the conductor to be instantaneously reversed in direction, the magnetic force surrounding it would not be instantly reversed everywhere in direction, but the reversal would be propagated outwards through space with a certain velocity which Maxwell showed was inversely as the square root of the product of the magnetic permeability and the dielectric constant or specific inductive capacity of the medium.
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  • The principal points of difference are that (I) the magnetic permeability, unlike the electric conductivity, which is independent of the strength of the current, is not in general constant; (2) there is no perfect insulator for magnetic induction, which will pass more or less freely through all known substances.
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  • To secure the highest possible permeability it is essential that the iron should be softened by careful annealing.
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  • For strong magnetizing forces (which in these experiments did not exceed II= 48.9) the permeability remains almost constant at its initial value (about 400), until the temperature is within nearly i oo of the critical point; then the permeability diminishes more and more rapidly until the critical point is reached and the magnetization vanishes.
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