Osmotic Regulation in the Crab-Eating Frog (Rana Cancrivora)

1961 ◽  
Vol 38 (3) ◽  
pp. 659-678 ◽  
Author(s):  
MALCOLM S. GORDON ◽  
KNUT SCHMIDT-NIELSEN ◽  
HAMILTON M. KELLY
Keyword(s):  
Fresh Water ◽  
External Medium ◽  
Short Circuit ◽  
Inorganic Ions ◽  
Short Circuit Current ◽  
Water Levels ◽  
Close Relative ◽  
Osmotic Regulation ◽  
Water Frogs ◽  
Nacl Concentration

1. The osmotic and ionic regulatory abilities of adults of the euryhaline crab-eating frog (Rana cancrivora) have been studied. Adult frogs tolerated environmental salinities as high as 28‰ at 30°C. Tadpoles of this form tolerated salinities as high as 39%‰ at the same temperature. 2. Changes in body weight of frogs following transfers to different environmental salinities indicate both that the skin of this frog is permeable to water and that these animals do not swallow large volumes of external medium, even in high salinities. 3. Above salinities of about 9%‰, plasma Δ rises with increasing environmental Δ. Plasma Δ is always higher than environmental Δ. Increases in plasma concentration above fresh-water levels are due partly to increased NaCl concentration (about 40%), partly to increased urea concentration (about 60%). Urea concentrations as high as 0.48 M (2.9%) have been measured. 4. Urinary Δ parallels plasma Δ, but is always lower than plasma Δ. Considerable quantities of urea are lost via the urine, even though urinary urea levels are below plasma levels. 5. Measurements of short-circuit current indicate that active uptake by the skin of inorganic ions continues in R. cancrivora acclimatized to high salinities. 6. R. cancrivora is no less susceptible to water loss by evaporation from the skin than are other amphibians. 7. In preference experiments R. cancrivora chooses salinities below 18%‰, but shows no strong preference for a particular salinity. 8. Similar observations on osmoregulatory mechanisms in a close relative of R. cancrivora, the tiger frog (R. tigerina), show that the latter species is similar to ordinary fresh-water frogs. 9. The striking physiological convergence between R. cancrivora and the elasmo-branch fishes is discussed, as are various possible implications of our data regarding nitrogen metabolism in tadpoles and kidney function in adult frogs.

Osmotic Regulation in Mosquito Larvae

1950 ◽  
Vol 27 (2) ◽  
pp. 145-157 ◽  
Author(s):  
J. A. RAMSAY
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
External Medium ◽  
Freezing Point ◽  
Anterior Part ◽  
Osmotic Regulation ◽  
Opposite Process ◽  
Normal Environment ◽  
Different Parts

1. The processes of osmotic regulation in the larvae of Aedes aegypti and of A. detritus have been studied by determination of the freezing-point of samples of fluid collected from different parts of the gut. 2. In A. aegypti, kept in fresh water (its normal environment), the fluid passing down the intestine to the rectum is isotonic with the haemolymph. In the rectum it becomes strongly hypotonic before being eliminated. 3. In A. detritus, kept in sea water (its normal environment), the opposite process is observed, the fluid in the rectum becoming hypertonic to the haemolymph and approximately isotonic with the external medium before being eliminated. 4. In A. detritus, which is able to live in dilute media as well as in sea water, the only two specimens from fresh water available for examination were found to have the rectal fluid hypotonic to the haemolymph. 5. The ability of A. detritus, not possessed by A. aegypti, to produce an hypertonic fluid in the rectum is tentatively associated with a region in the anterior part of the rectum and lined with an epithelium distinctly different from that in the remainder of the rectum. This anterior region has not been found in A. aegypti.

Osmotic Regulation in the Green Toad (Bufo Viridis)

1962 ◽  
Vol 39 (2) ◽  
pp. 261-270 ◽  
Author(s):  
MALCOLM S. GORDON
Keyword(s):  
Body Weight ◽  
Body Fluid ◽  
Short Circuit ◽  
Electrical Potential ◽  
Inorganic Ions ◽  
Short Circuit Current ◽  
Urine Concentration ◽  
Bufo Viridis ◽  
Green Toad ◽  
Toad Bufo

1. The osmotic and ionic regulatory abilities of adults of a freshwater population of the green toad (Bufo viridis) have been studied. These toads tolerated environmental salinities as high as 19% at temperatures near 25° C. Two individuals of another population of this species tolerated salinities as high as 23% 2. Changes in body weight of toads transferred to different environmental salinities indicate that the skin of this form is permeable to water. Rapid return to control levels of body weight indicate that drinking of external medium may be an important part of the initial adjustment to high salinities. 3. Above salinities of about 8% plasma Δ rises with increasing environmental Δ. Marked hypertonicity of the plasma is maintained in low salinities, but isotonicity with the medium is approached in higher salinities. Increases in plasma concentration above freshwater levels are due primarily to increased NaCl concentration (about 84%), partly to increased concentrations of urea (5-10%) and other osmotically active substances. 4. Urinary Δ is much lower than plasma Δ in dilute media, but becomes identical with plasma Δ above salinities of about 15%. Increases in urine concentration above freshwater levels are also due primarily to NaCl increase (74%). Considerable quantities of salt are lost via the urine. The kidneys seem to lose much of their ability to regulate urinary salt concentrations in high-salinity media. 5. Measurements of electrical potential and short-circuit current indicate that active uptake of inorganic ions by the skin continues in concentrated media, but at reduced rates. 6. Changes in muscle water, Na and K contents indicate the occurrence of some redistribution of water and salts between various body-fluid compartments as part of the salinity adaptation process. 7. In preference experiments, B. viridis chooses the land over any aquatic environment. Among aquatic environments it prefers those with salinities below 8%. 8. When combined with some earlier data by other workers who studied other populations of B. viridis, the present data indicate great uniformity of ionic and osmotic regulatory abilities among populations of this species. The marked differences between salinity tolerances of different populations are indicated to be due to differences in tissue tolerance of high body-fluid salinities.

The Water Balance of a Serpulid Polychaete, Mercierella Enigmatica (Fauvel)

1974 ◽  
Vol 60 (2) ◽  
pp. 331-338
Author(s):  
HELEN LE B. SKAER
Keyword(s):  
Water Balance ◽  
Fresh Water ◽  
Sea Water ◽  
External Medium ◽  
Inorganic Ions ◽  
Sodium Calcium

1. Mercierella enigmatica, a serpulid polychaete, lives in water ranging in concentration from fresh water to 150% sea water (< 1-55‰). 2. The concentrations of five inorganic ions (Na+, K+, Ca2+, Mg2+ and Cl-2) in the blood have been measured both during and after equilibration of the animals with media of altered salinity. 3. The concentrations of calcium and potassium have also been measured in filtrates of the blood from animals equilibrated in three media of differing salinity. 4. Concentrations of all the ions measured vary linearly with the concentration of the external medium. The levels of sodium, calcium (in filtered blood) and chloride are near the isionic line, while those of magnesium and potassium (even in filtered blood) are slightly higher in the blood over the whole range.

Ionic Regulation in the Palaemonid Prawn Palaemon (=Leander) Serratus

1954 ◽  
Vol 31 (4) ◽  
pp. 601-613 ◽  
Author(s):  
G. PARRY
Keyword(s):  
Sea Water ◽  
External Medium ◽  
Inorganic Ions ◽  
Osmotic Regulation ◽  
Ionic Regulation ◽  
Blood Concentrations ◽  
Antennal Gland

1. Analyses have been made of the blood and urine of Palaemon serratus for the inorganic ions Na, K, Ca, Mg, Cl, SO4 the animals being kept in 50, 100 and 120% sea water. 2. When the animal is in 100% sea water the concentrations of ions in the blood, expressed as percentages of their concentrations in the medium (to the nearest 5%) are as follows: Na, K and Cl, 85% Ca, 105% Mg, 20% SO4 10%. 3. When the animal is in 50% sea water the corresponding figures are: Na and Cl, 105%K, 120%; Ca, 200%; Mg, 20%; SO4 10%. 4. When the animal is in 120% sea water the corresponding figures are: Na, K and Cl, 85% Ca, 115% Mg, 30% SO4 20%. 5. The concentrations of Na, K and Ca in the urine are always slightly (≤20%) less than their concentrations in the blood. The concentration of Cl is slightly greater in the urine than in the blood (10-20%) and the concentrations of Mg and SO4 are very much greater, by factors of up to 7 times. The relative concentrations of ions blood and urine do not change substantially with changes in the external medium. 6. The antennal gland, although it plays no part in purely osmotic regulation, is no doubt partly responsible for maintaining the low blood concentrations of Mg and SO4.

The Energetics of Osmotic Regulation in Brackish- and Fresh-Water Animals

1954 ◽  
Vol 31 (4) ◽  
pp. 618-630 ◽  
Author(s):  
W. T. W. POTTS
Keyword(s):  
Surface Area ◽  
Fresh Water ◽  
Brackish Water ◽  
External Medium ◽  
Urine Concentration ◽  
Marine Animal ◽  
Osmotic Regulation ◽  
Moderate Reduction ◽  
Important Means ◽  
Theoretical Minimum

1. The dynamics of osmoregulation in an ideal semi-permeable animal are discussed. The theoretical minimum osmotic work is evaluated in terms of the surface area of the animal, its permeability and the concentrations of the blood, urine and external medium. 2. It is shown that: (a) The most important means whereby a marine animal entering brackish water can reduce the strain upon its osmoregulatory mechanisms is by reducing the concentration of its blood. (b) In a brackish-water animal the production of urine hypotonic to the blood has only a very small effect upon the osmotic work. (c) In a fresh-water animal the reduction of the urine concentration to the point at which it is isotonic with the medium can reduce the osmotic work by as much as 90%; but even a moderate reduction of the urine concentration, so that the urine is hypotonic to the blood but many times more concentrated than the medium, greatly reduces the osmotic work and is compatible with high osmoregulatory efficiency. 3. These conclusions are discussed with reference to some fresh-water animals.

Estimation Methods of Short Circuit Current using Normal PMU Measurements and Field Testing

2013 ◽  
Vol 133 (1) ◽  
pp. 37-44
Author(s):  
Suresh Chand Verma ◽  
Yoshiki Nakachi ◽  
Yoshihiko Wazawa ◽  
Yoko Kosaka ◽  
Takenori Kobayashi ◽  
...  
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Field Testing ◽  
Estimation Methods

About the Selection of a Single-Phase Short-Circuit Current on Earth in the Network With Low-Ohm Resistive Grounding of the Neutral

2017 ◽  
pp. 34-41
Author(s):  
Andrei V. MAIOROV ◽  
◽  
Kirill A. OSINTSEV ◽  
Andrei V. SHUNTOV ◽  
◽  
...  
Keyword(s):  
Single Phase ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Selection Of

Optical Absorption Enhancement in Polymer BHJ thin Film Using Ag Nanostructures: A Simulation Study

2020 ◽  
Vol 16 (4) ◽  
pp. 556-567
Author(s):  
Asma Khalil ◽  
Zubair Ahmad ◽  
Farid Touati ◽  
Mohamed Masmoudi
Keyword(s):  
Absorption Spectrum ◽  
Solar Cell ◽  
Methyl Ester ◽  
Butyric Acid ◽  
Organic Solar Cell ◽  
Short Circuit ◽  
Acid Methyl Ester ◽  
Short Circuit Current ◽  
Acid Methyl ◽  
Butyric Acid Methyl Ester

Background: The photo-absorption and light trapping through the different layers of the organic solar cell structures are a growing concern now-a-days as it affects dramatically the overall efficiency of the cells. In fact, selecting the right material combination is a key factor in increasing the efficiency in the layers. In addition to good absorption properties, insertion of nanostructures has been proved in recent researches to affect significantly the light trapping inside the organic solar cell. All these factors are determined to expand the absorption spectrum and tailor it to a wider spectrum. Objective: The purpose of this investigation is to explore the consequence of the incorporation of the Ag nanostructures, with different sizes and structures, on the photo absorption of the organic BHJ thin films. Methods: Through a three-dimensional Maxwell solver software, Lumerical FDTD, a simulation and comparison of the optical absorption of the three famous organic materials blends poly(3- hexylthiophene): phenyl C71 butyric acid methyl ester (P3HT:PCBM), poly[N-9″-heptadecanyl-2,7- carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]: phenyl C71 butyric acid methyl ester (PCDTBT:PCBM) and poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt- 4,7-(2,1,3-benzothiadiazole)]: phenyl C71 butyric acid methyl ester (PCDPDTBT:PCBM) has been conducted. Furthermore, FDTD simulation study of the incorporation of nanoparticles structures with different sizes, in different locations and concentrations through a bulk heterojunction organic solar cell structure has also been performed. Results: It has been demonstrated that embedding nanostructures in different locations of the cell, specifically in the active layer and the hole transporting layer had a considerable effect of widening the absorption spectrum and increasing the short circuit current. The effect of incorporation the nanostructures in the active layer has been proved to be greater than in the HTL. Furthermore, the comparison results showed that, PCDTBT:PCBM is no more advantageous over P3HT:PCBM and PCPDTBT:PCBM, and P3HT:PCBM took the lead and showed better performance in terms of absorption spectrum and short circuit current value. Conclusion: This work revealed the significant effect of size, location and concentration of the Ag nanostructures while incorporated in the organic solar cell. In fact, embedding nanostructures in the solar cell widen the absorption spectrum and increases the short circuit current, this result has been proven to be significant only when the nanostructures are inserted in the active layer following specific dimensions and structures.

Determining the exciton diffusion length of copper phthalocyanine in operating planar-heterojunction organic solar cells

2020 ◽  
Vol 89 (3) ◽  
pp. 30201 ◽  
Author(s):  
Xi Guan ◽  
Shiyu Wang ◽  
Wenxing Liu ◽  
Dashan Qin ◽  
Dayan Ban
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Diffusion Length ◽  
Copper Phthalocyanine ◽  
Short Circuit ◽  
Thick Layer ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length

Organic solar cells based on planar copper phthalocyanine (CuPc)/C60 heterojunction have been characterized, in which a 2 nm-thick layer of bathocuproine (BCP) is inserted into the CuPc layer. The thin layer of BCP allows hole current to tunnel it through but blocks the exciton diffusion, thereby altering the steady-state exciton profile in the CuPc zone (zone 1) sandwiched between BCP and C60. The short-circuit current density (JSC) of device is limited by the hole-exciton scattering effect at the BCP/CuPc (zone 1) interface. Based on the variation of JSC with the width of zone 1, the exciton diffusion length of CuPc is deduced to be 12.5–15 nm. The current research provides an easy and helpful method to determine the exciton diffusion lengths of organic electron donors.

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