scholarly journals The Transpiration of Terrestrial Isopods

1955 ◽  
Vol 32 (2) ◽  
pp. 238-255
Author(s):  
E. BURSELL
Keyword(s):  
Melting Point ◽  
Transpiration Rate ◽  
Blood Concentration ◽  
Initial Rate ◽  
Body Fluids ◽  
Structural Alteration ◽  
Progressive Decrease ◽  
Terrestrial Isopods ◽  
High Initial Rate ◽  
Rate Of Evaporation

1. The transpiration of three species of Isopoda has been investigated; Armadillidium shows the highest resistance to desiccation, Oniscus the least, and Porcellio is intermediate. 2. The permeability of isopod cuticle is limited by lipoids which impregnate the endocuticle. If the temperature is raised above the lipoid melting-point a marked increase in permeability results. 3. Isopods show a characteristic decline in transpiration rate during exposure to desiccating atmospheres. The high initial rate of evaporation is due mainly to loss of water from layers of the cuticle external to the lipoid barrier. 4. There is a progressive decrease in the permeability of the integument during desiccation. This is brought about by a shrinkage of the cuticle, which leads to a closer packing of lipoid molecules. The mechanism of this structural alteration is based on an interaction between endocuticular proteins and the ionic constituents of body fluids; in the course of desiccation the blood concentration increases and there is a corresponding decrease in the dispersion of endocuticular elements.

RATE OF EVAPORATION FROM A FREE-WATER SURFACE AS INFLUENCED BY EXPOSURE

1961 ◽  
Vol 41 (1) ◽  
pp. 199-203 ◽  
Author(s):  
A. C. Carder
Keyword(s):  
Water Surface ◽  
Meteorological Factors ◽  
Free Water ◽  
Water Evaporation ◽  
High Wind ◽  
Progressive Decrease ◽  
Factors Affecting ◽  
Wind Velocities ◽  
Rate Of Evaporation ◽  
Low Rate

In a 3-year free-water evaporation study, an evaporimeter tank in the open field lost 34.5 per cent more water than a tank sheltered by buildings and trees. Meteorological factors responsible for this difference appear to be high wind velocities and long daily periods of sunshine. Changes in temperature regime had no effect.Difference in evaporation from the two tanks led to examination of data obtained over 35 years from the sheltered tank. It was found that, although there was a progressive decrease in amount of evaporation over the years from this tank, rainfall at the same time had increased and that the effect of this increase on evaporation was roughly equal to that of all other factors affecting evaporation, such as a change in exposure, etc. Thus, the comparatively low rate of evaporation from the sheltered tank was undoubtedly due in part to the proximity of buildings and trees which had been established.

scholarly journals Mutating the dileucine motif of the human β2-adrenoceptor reduces the high initial rate of receptor phosphorylation by GRK without affecting postendocytic sorting

2010 ◽  
Vol 635 (1-3) ◽  
pp. 9-15 ◽  
Author(s):  
Hibah O. Awwad ◽  
Ellen E. Millman ◽  
Estrella Alpizar-Foster ◽  
Robert H. Moore ◽  
Brian J. Knoll
Keyword(s):  
Initial Rate ◽  
Receptor Phosphorylation ◽  
Dileucine Motif ◽  
High Initial Rate

The thermal decomposition of RDX at temperatures below the melting point. I. Comments on the mechanism

1970 ◽  
Vol 23 (4) ◽  
pp. 737 ◽  
Author(s):  
JJ Batten ◽  
DC Murdie
Keyword(s):  
Thermal Decomposition ◽  
Melting Point ◽  
Liquid Phase ◽  
Condensed Phase ◽  
Initial Rate ◽  
Decomposition Products ◽  
Sample Geometry

Two mechanisms have recently been proposed to explain the behaviour of the initial rate of decomposition of RDX, with change in sample geometry. These are (i)that the decomposition proceeds by concurrent gas and liquid phase reactions, and (ii) that gaseous decomposition products influence the rate of decomposition of undecomposed RDX in the condensed phase. In this paper it is concluded that mechanism (ii) is the more probable when the reaction is carried out in the presence of nitrogen.

Basic Reactions Occurring during Rubber Reclaiming. I. The Influence of Reclaiming Media, Antioxidant, and Defibering Agents on Vulcanized Natural Rubber at 195 Pounds Per Square Inch Gauge Pressure (196.6° C)

1948 ◽  
Vol 21 (4) ◽  
pp. 895-908 ◽  
Author(s):  
D. S. Le Beau
Keyword(s):  
Natural Rubber ◽  
Initial Rate ◽  
Progressive Increase ◽  
Oxidation Products ◽  
Double Bonds ◽  
Open Steam ◽  
Chain Reactions ◽  
Surrounding Atmosphere ◽  
High Initial Rate ◽  
Oxidative Attack

Abstract The influence of surrounding atmosphere, antioxidant, and defibering agents at 196.6° C on the hydrocarbon of rubber was studied by subjecting a laboratory prepared, pure-gum, natural rubber compound to reclaiming in the absence of any reclaiming oils or chemicals. Data obtained on the amount of acetone and chloroform extracts and on the unsaturation of the reclaims and the chloroform extracts could therefore be interpreted in terms of the effect of the factors mentioned above on the rubber hydrocarbon and not as the effect of any chemicals added to the rubber to promote reclaiming. It was found that the effect of the surrounding atmosphere during reclaiming is the predominant factor in the reaction. Acidic surrounding atmospheres result in a slow and rather uniform rate of molecular breakdown and in the formation of small amounts of oxidation products. Apparently no secondary oxidative attack occurs at the double bonds. An open steam atmosphere provides the greatest amount of oxidized products and also a high initial molecular breakdown, followed by a slow progressive increase in it as the reclaiming periods are lengthened. A decrease in the unsaturation value of the acetone extracted reclaim indicates that secondary oxidative attack at the double bonds occurs at long reclaiming intervals. Alkaline reclaiming atmospheres provide little if any oxidation products and result in a very high initial rate of molecular breakdown. Longer reclaiming periods do not change further the amount of molecular breakdown. The very small amounts of oxygen necessary to promote the reclaiming reactions, the dependence of the course of these reactions on the acidity or alkalinity of the surrounding reclaiming media, together with the high initial rate of molecular breakdown reactions under conditions where such rate would be speeded up, permit the tentative explanation of these reactions on the basis of hydroperoxidic chain reactions. Further experiments along this line are being carried out.

scholarly journals On the viscosity of the vapour of iodine

1915 ◽  
Vol 91 (627) ◽  
pp. 201-208 ◽  
Keyword(s):  
Melting Point ◽  
Transpiration Rate ◽  
Pressure Difference ◽  
Capillary Tube ◽  
Evaporation And Condensation ◽  
Previous Communication ◽  
Liquid Bromine ◽  
Different Temperatures ◽  
Bromine Vapour

In a previous communication I have described the measurements I have made of the viscosity of bromine vapour. The method used for this purpose involved the distillation of bromine from one vessel to another through a capillary tube. The pressure difference between the two ends of the capilllary was established by maintaining the two vessels at suitable different temperatures, and the rate of transpiration of the bromine vapour was estimated by observing the volume of the liquid bromine which evaporated in a given time. It was hoped that the same method could be applied to iodine by adjusting the temperatures of evaporation and condensation of values above the melting point of iodine (113° C.), and measuring the transpiration rate by means of the disappearance of liquid from the evaporation vessel. Preliminary experiments, however, soon revealed the fact that the liquid iodine was not sufficiently mobile, and its surface was too indefinite and variable in shape to allow small changes of volume to be observed. It was, therefore, found necessary to modify in several respects the method used with bromine.

STUDIES ON THE FORMATION OF HEXAMINE

1947 ◽  
Vol 25b (4) ◽  
pp. 387-396 ◽  
Author(s):  
Mary L. Boyd ◽  
C. A. Winkler
Keyword(s):  
Aqueous Solution ◽  
Mercuric Chloride ◽  
Initial Rate ◽  
Rapid Rate ◽  
Large Excess ◽  
Lower Yield ◽  
High Initial Rate

Rate curves have been determined for the reaction of ammonia and formaldehyde in aqueous solution at 0 °C. and 35 °C., over a range of initial mole ratios (formaldehyde: ammonia) of 0.25 to 2.0. For each set of conditions, three curves have been obtained on the basis of ammonia consumed, formaldehyde consumed, and material precipitated with mercuric chloride respectively.At 0 °C. the three rate curves tend to approximate one another in a large excess of ammonia but are widely separated in excess formaldehyde. The reverse is true at 35 °C. The reaction is characterized by a high initial rate of formation of hexamine, this rapid rate being maintained to a lower yield of hexamine the more dilute the solution. The existence of a stable by-product in excess formaldehyde is indicated by the variation in final yields of hexamine, when these are calculated on the basis of formaldehyde consumed, ammonia consumed, or material precipitated with mercuric chloride.A mechanism for the reaction has been suggested.

Oviposition Behaviour in the Two Strains of the Rice Weevil, Calandra Oryzae Linn. (Coleopt., Curculionidae)

1951 ◽  
Vol 28 (3) ◽  
pp. 281-297
Author(s):  
F. SEGROVE
Keyword(s):  
Egg Production ◽  
Initial Rate ◽  
Large Strain ◽  
Small Strain ◽  
Oviposition Behaviour ◽  
Rice Weevil ◽  
Rapid Decline ◽  
High Initial Rate ◽  
Moisture Conditions ◽  
Better Than

The oviposition behaviour of the large strain of Calandra oryzae has been investigated at 20 and 25°C. and under moisture conditions equivalent to 50 and 70% R.H. The small strain of the weevil has been investigated at 25°C. and 70% R.H. At either temperature the lower humidity shortens the life of the insect and depresses the rate of oviposition so that fecundity is of a low order. Changes of temperature with a fixed humidity alter the rate of oviposition but have little effect on the total egg production. Under all conditions the pattern of oviposition remains the same, the oviposition rate rising to a peak in the earlier weeks of maturity and subsequently declining. Increasing the amount of grain leads to increasing egg production. It is unlikely that conditions for maximum fecundity were realised in the experiments. Isolating females in the early weeks of maturity leads to a high initial rate of oviposition, followed by a more rapid decline and little overall increase in fecundity. At 25°C. and 70% R.H. the fecundity of the large strain is of the order of 50% higher than that of the small strain. The distribution of eggs between grains differs in the two strains, the small strain distributing its eggs better than random, the large strain tending to overcrowd its eggs. The evidence suggests that this is due to the larger weevils' greater preference for large grains. By correlating the results with those from other sources it is nevertheless concluded that both strains tend to avoid laying in grains already containing life. The importance of this factor in oviposition behaviour is discussed.

Inoculation triggers freezing at high subzero temperatures in a freeze-tolerant frog (Rana sylvatica) and insect (Eurosta solidaginis)

1990 ◽  
Vol 68 (3) ◽  
pp. 506-510 ◽  
Author(s):  
Jack R. Layne Jr. ◽  
Richard E. Lee Jr. ◽  
Janet L. Huang
Keyword(s):  
Melting Point ◽  
Water Content ◽  
Direct Contact ◽  
Rana Sylvatica ◽  
High Water ◽  
Body Fluids ◽  
High Water Content ◽  
Eurosta Solidaginis ◽  
Subzero Temperatures ◽  
Freeze Tolerant

Freezing of animals is often portrayed to begin after they supercool several degrees Celsius below the melting point of body fluids. This supposition is based on laboratory protocol that usually exposes animals only to dry air during freezing episodes, whereas, in nature, animals may be in direct contact with external ice or snow at temperatures above the supercooling point of their body fluids. This raises the possibility that ice nucleation may occur across the epithelium or cuticle, causing the freezing of body fluids. We tested this possibility in two freeze-tolerant animals, the wood frog, Rana sylvatica, and the goldenrod gall fly, Eurosta solidaginis. Frogs remained supercooled for 3 h at −1.5 to −2.0 °C when kept on an unfrozen surface; however, they began to freeze in less than 30 s after coming in direct contact with ice crystals. Seeding occurred in less than 1 min across isolated patches of frog skin held in a modified Ussing chamber. Similarly, externally moistened larvae of E. solidaginis froze at higher temperatures than dry larvae. Likewise, within galls containing a relatively high water content (65.8%), larvae froze at higher temperatures than ones found in drier galls (19.6%). Therefore, animals may freeze at high subzero temperatures, at or near the melting point of their body fluids, owing to transepithelial ice inoculation. In E. solidaginis, exposure to sufficient moisture to trigger inoculation declines as winter approaches; thus, this avenue for freezing seems limited to autumn, when plant galls have a high water content. This study further emphasizes the need to use care in extrapolating laboratory-determined supercooling points as an approximation of the response of animals in the field.

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