scholarly journals THE KINETICS OF OSMOTIC SWELLING IN LIVING CELLS

1926 ◽  
Vol 9 (5) ◽  
pp. 697-707 ◽  
Author(s):  
Morton McCutcheon ◽  
Baldwin Lucke
Keyword(s):  
Diffusion Processes ◽  
Sea Water ◽  
Living Cells ◽  
Cell Permeability ◽  
Effect Of Temperature ◽  
Osmotic Swelling ◽  
A Value ◽  
Wide Range ◽  
The One ◽  
Kinetics Of

The rate of swelling of unfertilized sea urchin eggs in hypotonic sea water was investigated. Analysis of curves leads to the following conclusions. 1. The rate of swelling follows the equation, See PDF for Equation where Veq., V0, and Vt stand for volume at equilibrium, at first instant, and at time t, respectively, the other symbols having their usual significance. This equation is found to hold over a wide range of temperatures and osmotic pressures. This relation is the one expected in a diffusion process. 2. The rate of swelling is found to have a high temperature coefficient (Q10 = 2 to 3, or µ = 13,000 to 19,000). This deviation from the usual effect of temperature on diffusion processes is thought to be associated with changes in cell permeability to water. The possible influence of changes in viscosity is discussed. 3. The lower the osmotic pressure of the solution, the longer it takes for swelling of the cell. Thus at 15° in 80 per cent sea water, the velocity constant has a value of 0.072, in 20 per cent sea water, of 0.006.

Kinetics of Water and Chloride Exchanges During Adaptation of the European Eel to Sea Water

1973 ◽  
Vol 58 (1) ◽  
pp. 105-121
Author(s):  
R. KIRSCH ◽  
N. MAYER-GOSTAN
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Maximum Level ◽  
Progressive Increase ◽  
Plasma Sodium ◽  
European Eel ◽  
Drinking Rate ◽  
The One ◽  
Kinetics Of

Using isotopic procedures, the drinking rate and chloride exchanges were studied in the eel Anguilla anguilla during transfer from fresh water to sea water. 1. Following transfer to sea water there is a threefold increase of the drinking rate (lasting about 1 h). Then it falls to a minimum after 12-16 h and rises again to a maximum level about the seventh day after the transfer. Then a gradual reduction leads to a steady value which is not significantly different from the one observed in fresh water. 2. The changes with time of the plasma sodium and chloride concentrations are given. Their kinetics are not completely alike. 3. The chloride outflux increases 40-fold on transfer of the eel to sea water, but even so it is very low. After the sixth hour in sea water there is a progressive increase in the flux, so that on the fourth day it is higher (500 µ-equiv. h-1.100 g-1) than in the seawater-adapted animals (230 µ-equiv.h-1.100 g-1). 4. Drinking rate values in adapted animals are discussed in relation to the external medium. The kinetics of the drinking rate together with variations in body weights after freshwater-seawater transfer are discussed in relation to the possible stimulus of the drinking reflex. 5. Chloride fluxes (outflux, net flux, digestive entry) are compared and lead one to assume that in seawater-adapted fish one-third of the chloride influx enters via the gut and two-thirds via the gills.

scholarly journals A Rare Natural Benzo[k,l]xanthene as a Turn-Off Fluorescent Sensor for Cu2+ Ion

2020 ◽  
Vol 21 (18) ◽  
pp. 6933
Author(s):  
Giuseppe Floresta ◽  
Nunzio Cardullo ◽  
Carmela Spatafora ◽  
Antonio Rescifina ◽  
Corrado Tringali
Keyword(s):  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Limit Of Detection ◽  
Copper Ions ◽  
Fluorescent Sensor ◽  
Copper Ion ◽  
Living Cells ◽  
A Value ◽  
Wide Range ◽  
Catechol Group

Rapid and efficient analyses of copper ions are crucial to providing key information for Cu2+ in living cells because of their biological importance. In this study, we reported one new turn-off fluorescent sensor for Cu2+ with a benzo[k,l]xanthene core, which served as an efficient cation sensor for copper ion over a wide range of other cations (Na+, K+, Ag+, Hg2+, Cd2+, Co2+, Ni2+, Zn2+, Mg2+, and Fe3+) owing to the catechol group in the aromatic core. The sensor showed selectivity for Cu2+ over other ions; the logKβ for Cu2+ binding to compound 1 had a value of 13.265. In the presence of Cu2+, sensor 1 provided significant fluorescence decrement; Co2+, and Ni2+ caused a fluorescence decrement when employed at a higher concentration than Cu2+, while Na+, K+, Hg2+, Cd2+, Zn2+, and Mg2+ metal ions produced only minor changes in fluorescence intensity. Fluorescence experiments demonstrate that compound 1 may have an application as a fluorescent probe for detecting Cu2+ with a limit of detection of 0.574 µM.

scholarly journals THE OSMOTIC PROPERTIES OF LIVING CELLS (EGGS OF ARBACIA PUNCTULATA)

1931 ◽  
Vol 14 (3) ◽  
pp. 393-403 ◽  
Author(s):  
Morton McCutcheon ◽  
Balduin Lucké ◽  
H. Keffer Hartline
Keyword(s):  
Surface Tension ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Sea Water ◽  
Living Cells ◽  
Arbacia Punctulata ◽  
Wide Range ◽  
Inactive Cell ◽  
Osmotic Properties

We have attempted to answer the question: How nearly ideal, as an osmometer, is the unfertilized Arbacia egg? The following conclusion have been reached: 1. Volumes can be measured accurately over a wide range of pressures since the cell is in general spherical and does not suffer deformation from its own weight or other factors. 2. The product of volume and pressure is approximately constant, if allowance be made for osmotically inactive cell contents. It is computed that from 7 to 14 per cent of cell volume is occupied by osmotically inactive material. 3. Evidence is presented that no appreciable escape of cell contents occurs while the cell is in hypotonic sea water; that, therefore, the semipermeability of the membrane is approximately perfect, so long as injury to the cell is avoided. 4. In comparison with osmotic pressure the influence of other forces, such as elasticity or surface tension, on cell volume must in these experiments be slight.

scholarly journals Kinetics of Grape Seed Oil Epoxidation in Supercritical CO2

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1490
Author(s):  
Juan Catalá ◽  
Jesús Manuel García-Vargas ◽  
María Jesús Ramos ◽  
Juan Francisco Rodríguez ◽  
María Teresa García
Keyword(s):  
Supercritical Co2 ◽  
Seed Oil ◽  
Grape Seed ◽  
Effect Of Temperature ◽  
Side Reactions ◽  
Secondary Products ◽  
Yield Data ◽  
Grape Seed Oil ◽  
Wide Range ◽  
Kinetics Of

The epoxidation of grape seed oil in supercritical CO2, to the best of our knowledge, has been only superficially described in the literature, apart from a short communication and our own previous published work on the topic. In this work, a thorough study of the performance of the supercritical epoxidation of grape seed oil is performed in a wide range of conditions, and the kinetic parameters of the supercritical epoxidation of vegetable oils are reported for the first time in the literature. The experimental work has covered a 40–60 °C temperature range at 150 bar, sampling during a period of 48 h. The nature and extent of the side reactions and secondary products obtained have been evaluated, being hydrolysis products and their oligomerization derivatives the major by-products. Reaction rate constants (10−2 h−1 order) and activation energy parameters were finally calculated from the experimental conversion and epoxy yield data to establish the effect of temperature on the kinetics of the process.

scholarly journals Quantifying the spatiotemporal dynamics of IRES versus Cap translation with single-molecule resolution in living cells

2020 ◽  
Author(s):  
Amanda Koch ◽  
Luis Aguilera ◽  
Tatsuya Morisaki ◽  
Brian Munsky ◽  
Timothy J. Stasevich
Keyword(s):  
Single Molecule ◽  
Living Cells ◽  
Host Cells ◽  
Spatial Distributions ◽  
Dependent Manner ◽  
Single Molecule Tracking ◽  
Single Molecule Level ◽  
The One ◽  
Kinetics Of ◽  
Relative Kinetics

ABSTRACTViruses use IRES sequences within their RNA to hijack translation machinery and thereby rapidly replicate in host cells. While this process has been extensively studied in bulk assays, the dynamics of hijacking at the single-molecule level remain unexplored in living cells. To achieve this, we developed a bicistronic biosensor encoding complementary repeat epitopes in two ORFs, one translated in a Cap-dependent manner and the other translated in an IRES-mediated manner. Using a pair of complementary probes that bind the epitopes co-translationally, our biosensor lights up in different colors depending on which ORF is being translated. In combination with single-molecule tracking and computational modeling, we measured the relative kinetics of Cap versus IRES translation and show: (1) Two non-overlapping ORFs can be simultaneously translated within a single mRNA; (2) EMCV IRES-mediated translation sites recruit ribosomes less efficiently than Cap-dependent translation sites but are otherwise nearly indistinguishable, having similar mobilities, sizes, spatial distributions, and ribosomal initiation and elongation rates; (3) Both Cap-dependent and IRES-mediated ribosomes tend to stretch out translation sites; (4) Although the IRES recruits two to three times fewer ribosomes than the Cap in normal conditions, the balance shifts dramatically in favor of the IRES during oxidative and ER stresses that mimic viral infection; and (5) Translation of the IRES is enhanced by translation of the Cap, demonstrating upstream translation can positively impact the downstream translation of a non-overlapping ORF. With the ability to simultaneously quantify two distinct translation mechanisms in physiologically relevant live-cell environments, we anticipate bicistronic biosensors like the one we developed here will become powerful new tools to dissect both canonical and non-canonical translation dynamics with single-molecule precision.Graphical Abstract

Chemisorption of hydrogen on nickel–magnesia catalysts. Part I. General kinetic characteristics

1969 ◽  
Vol 47 (16) ◽  
pp. 2933-2941 ◽  
Author(s):  
N. S. Viswanathan ◽  
L. M. Yeddanapalli
Keyword(s):  
Experimental Data ◽  
Nickel Catalysts ◽  
Activation Energies ◽  
Effect Of Temperature ◽  
Hydrogen Chemisorption ◽  
Kinetic Characteristics ◽  
Wide Range ◽  
Elovich Equation ◽  
Kinetics Of

A detailed study of the kinetics of hydrogen chemisorption on 3 different nickel catalysts, supported on magnesia and prepared by coprecipitation, has been made over a wide range of pressures and temperatures. The results have been analyzed in the light of the Elovich equation. Experimental data obtained by variations of pressure and temperature indicate the existence of a number of stages in the chemisorption process and support the multiple kinetic stage hypothesis suggested by Low. The effect of temperature on the parameters has been studied, and relations obtained which have been used to calculate activation energies for each of the stages.

Leaching Kinetics of Gold Involved in the System S2O32--EDTA-Cu2+

2020 ◽  
Vol 1001 ◽  
pp. 212-218
Author(s):  
Peng Zhi Xiang ◽  
Chao Deng ◽  
Huang Yao ◽  
Long Jiang Liu ◽  
S. Mogdal
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Reaction Order ◽  
Effect Of Temperature ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Gold Ores ◽  
Remarkable Effect ◽  
Copper Addition ◽  
A Value ◽  
Kinetics Of

Thiosulphate gold leaching is an alternative technology to the cyanidation of gold ores. Ethylenediaminetetraacetic acid is referred to as EDTA.A study on the leaching kinetics of gold involved in the system S2O32--EDTA-Cu2+ for the gold in this paper. The effect of temperature and of the addition of copper has been also analyzed, temperature has a remarkable effect over the overall reaction rate in the range from 293 to 323k, the result shows that the leaching process conforms to the chemical control model. The concentration of [S2O32-] considerably affects the leaching rate obtaining a value of for the order of reaction in the range of concentrations from 0.05 to 0.3 mol/L of S2O32- which obtaining a reaction order of 1.029. Copper addition favored the leaching rate of gold which obtaining a reaction order of 0.441,Thiosulphater addition also favored the leaching rate of gold .kinetics model was established which is 1−(1−x)1/3=4950.8c (S2O32-)1.029c (Cu2+)0.441exp (-9911/8.314T).

The Effect of Temperature and Damage Energy on Amorphization in Zircon

1998 ◽  
Vol 540 ◽  
Author(s):  
W. J. Weber ◽  
R. Devanathan ◽  
A. Meldrum ◽  
L. A. Boatner ◽  
R. C. Ewing ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Effect Of Temperature ◽  
Critical Displacement ◽  
Critical Dose ◽  
Recovery Processes ◽  
Complex Process ◽  
Wide Range ◽  
Significant Difference ◽  
Natural Zircon ◽  
Kinetics Of

AbstractSeveral groups have irradiated single crystals of synthetic and natural zircon (ZrSiO4) with a wide range of ions (from He to Bi) over a wide range of temperatures. The results of these studies show that amorphization in zircon is controlled by a variety of parameters and is a more complex process than previously thought. The critical dose for amorphization increases with temperature, similar to other materials. However, the critical displacement dose (in dpa) for amorphization is significantly higher at lower temperatures (below 500 K) for very heavy ions, such as Pb and Bi. This unusual dependence on the damage energy density has not been observed previously in other materials. Possible explanations for this behavior in terms of amorphization mechanisms are discussed. In addition, there is a significant difference in the temperature dependence of the critical dose in synthetic and natural zircons, which suggests that the impurities in natural zircons may affect the kinetics of recovery processes.

«Cloud» diplomacy as a trend in the era of a pandemic: the experience of Italy

2021 ◽  
Author(s):  
K.M. Tabarintsevа-Romanova
Keyword(s):  
Foreign Policy ◽  
Virtual Communication ◽  
Additional Information ◽  
A Value ◽  
Wide Range ◽  
Speed Up ◽  
The Government ◽  
The One ◽  
Operational Issues ◽  
Digital Diplomacy

2020 became a turning point for many spheres of life, and diplomatic activity was no exception. In the conditions of «closed» borders, diplomatic offi cers had to look for new forms of interaction. The result of such searches was the phenomenon of «cloud» diplomacy, as one of the subspecies of digital diplomacy. As the analysis of the conducted research has shown, even among diplomats there is no consensus on the digitalization of foreign policy. On the one hand, it allows you to reduce the fi nancial and time costs for «live» meetings and speed up the discussion and resolution of operational issues; on the other hand, such virtual communication does not allow «catching the true mood» of the interlocutor and limits his ability to collect additional information. Based on the study of the information presented on the offi cial websites of the President, the government and the Ministry of Foreign Aff airs for the period from 01.03.2020 to 31.12.2020, we came to the following conclusions: 1) digitalization has fi rmly entered the arsenal of means of implementing foreign policy activities; 2) «cloud» diplomacy allows you to discuss a wide range of topical issues; 3) «cloud» diplomacy has not become a priority tool in the work of diplomats; those. it has a utilitarian character, not a value-semantic one. At the same time, the introduction of digital means of communication into circulation made it possible to more actively involve non-state actors in the process of foreign policy interaction: non-profi t organizations, individuals, etc. In addition, the digitalization process forced offi cial institutions and politicians to actively use social networks in their daily activities as a tool for direct communication with society. Summing up, we note that the isolation regime all over the world has provoked a real «boom» in the fi eld of digital communications, which have become an integral part of international relations in the paradigm of the new «normality».

scholarly journals The sea water temperature impact upon Gonothyraea loveni (Allman) hydroid development on the artificial substrates in the Sevastopol Bay (the Black Sea)

2019 ◽  
Author(s):  
Keyword(s):  
Water Temperature ◽  
Black Sea ◽  
Sea Water ◽  
Seawater Temperature ◽  
Artificial Substrates ◽  
Effect Of Temperature ◽  
The Black Sea ◽  
Temperature Range ◽  
Wide Range ◽  
Sevastopol Bay

The effect of seawater temperature on the subsidence and development of the Gonothyraea loveni (Allman) hydroid at a specific point in the water area was discussed This allows us to trace the connection of seasonal changes in sea temperature with the process of sedimentation of planules and the development of hydroid G. loveni on artificial substrates of various exposures in the Sevastopol bay. Observations were carried out over two periods: from 1979 to 1987. and from 2011 to 2015. The temperature range of 5-10 °C corresponds to the subsidence of planul on plates with a community 10 days aged in the autumn and spring periods. The peak of subsidence was detected at a water temperature of 9 °C. At this time, the greatest number of plates with settled hydroids was detected (22%). The number of hydrotecas in the temperature range of 11-19 °C reaches maximum values due to sedimentation and active growth of colonies, since the frequency of occurrence of plates with hydroids during this period is halved and remains at this level at higher temperatures (17-24 °C). With an increase in the exposure of substrates up to 30 days, the bulk of the plates with hydroid (80%) are concentrated in the temperature range of 6–11 °C. When the temperature of water in the sea is 16-24 °C, plates with hydroids are less than 5%, which is determined in addition to the effect of temperature by the massive subsidence of Botryllys schlosseri (Pallas), which replaces the hydroid. In communities of 2-12 months of age, the hydroid G. loveni develops over a wide range of temperatures, from 5 to 23 °C. Dynamic changes in communities show that the growth of colonies occurs at a temperature of 5-9 °C with a maximum intensity of 10 to 15 °C. At temperatures above 17 °C, the reduction of colonies occurs. Key words: subsidence, development of hydroid Gonothyraea loveni, the temperature of the sea water of the Sevastopol Bay, the Black sea

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