Synopsis of Recently Submitted PhD Thesis

Sinha, Arun Kumar

doi:10.1080/02564602.1984.11437530

Cited by 7 publications

(13 citation statements)

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“…Marine and estuarine species (Bliding, 1957;Nienhuis, 1974) share basically the same life history. The ploidy is the same as that found by Geitler (I936), Sinha (1958) and Faridi (1983) for European populations of the species. Lateral syngamy occurs in a very similar manner to that described for Cladophora surera and Chaetomorpha exilis- sima (Parodi, 1990), but is different from the process described by Bliding (1957) for R. riparium and R. kochianum, since in our case flagellar reabsorption was immediate and quadriflagellate zygotes were therefore not observed.…”

Section: Discussionsupporting

confidence: 70%

“…On the basis of this uniformity under natural conditions and variations in other morphological features only under culture conditions, we consider 2(4) nuclei per cell to be a good diagnostic character for the species R. hieroglyphicum. This contradicts Sinha (1958) who put little value on this character because of its variability in culture. We consider it more appropriate to interpret this variation as yet another case of teratology.…”

Section: Discussioncontrasting

confidence: 44%

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Life history of freshwater populations ofRhizoclonium hieroglyphicum(Cladophorales, Chlorophyta)

Parodi

Cáceres

1993

European Journal of Phycology

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Section: Discussionsupporting

confidence: 70%

Section: Discussioncontrasting

confidence: 44%

Life history of freshwater populations ofRhizoclonium hieroglyphicum(Cladophorales, Chlorophyta)

Parodi

Cáceres

1993

European Journal of Phycology

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“…The time lag estimated by Sinha (1980) for the liquid to vapor transition over a wide range of helium bath temperatures is from 2 to 10 ns. Any experiment testing homogeneous nucleation theory must last 10 ns or longer following transition to the final metastable state to be considered a steady state experiment.…”

Section: Chapter IV Time Development Of Nucleation Homogeneous Nucleamentioning

confidence: 99%

“…This sets the upper limit to the speed at which the experiment can be conducted. Evidently the inequality Tm » TS must hold in order that an experiment can be compared with theory.The time lag estimated by Sinha (1980) for the liquid to vapor transition over a wide range of helium bath temperatures is from 2 to 10 ns. Any experiment testing homogeneous nucleation theory must last 10 ns or longer following transition to the final metastable state to be considered a steady state experiment.…”

mentioning

confidence: 99%

The Tensile Strength of Liquid Helium Four

Nissen¹

2000

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It is well known that most liquids exhibit a tensile strength which is much smaller in magnitude than the tensile strength predicted by homogeneous nucleation theory. This lack of agreement is usually attributed to the difficulty of preparing liquid samples free from foreign gases which act as heterogeneous nucleation sites.Liq"lid heliurr. occupies a unique place among liquids for tensile strength measurements because all fcreign gases are frozen OLt at liquid helium temperatures. LIST OF FIGURESAt Equilibrium, a van der Waals substance Exhibits a Phase Change . . . . . 2.A Schematic Representation of the Work If instead of expanding the stable liquid slowly at equilibrium, the volume is suddenly increased, the liquid will penetrate into the metastable region along the curve BC. The metastable state is a state in which the Gibbs free energy is at a local rather than a global minimum.After a characteristic mean time, , which is highly dependent on the depth of penetration into the metastable region, the liquid will decompose to a stable equilibrium configuration on the coexistence curve. When T/T c is less than about 0.8, rapid stretching of the liquid into the metastable region can result in negative pressure such as point G in Fig. 1. Point C lies on the liquid spinodal, the curve marking the transition to instability, and represents a true limit to the tensile strength of the liquid. In practice this limit is not reached, rather the tensile strength is determined by kinetic rates of bubble formation in the metastable region. THE WORK REQUIRED TO FORM A BUBBLEThe rate of bubble formation is calculated by considering the minimum work that must be done to form a vapor bubble in the liquid. An amount of work equal to the surface tension times the surface area, aA, must be done to form a cavity. Part of the work is done by the gas vaporized into the cavity so that the total work (W) needed to ·form a bubble iswhere PG is the pressure of the gas in the bubble, PL is the pressure of the surrounding liquid, VG is the volume of the bubble, x is the number of molecules vaporized into the cavity, ~G and ~L are the chemical potentials of the gas and vapor respectively. On the coexistence curve, the pressure of the gas and the pressure of the liquid are equal to the vapor pressure. The chemical potentials are also equal on the coexistence curve, so that the work necessary to form a bubble rises to infinity as the bubble radius is increased (curve a of Fig.2). If the liquid is brought rapidly into the metastable region by means of a pressure excursion .then the following conditions will hold: PL < P G and ~ G < ~ L. Under these conditions, the work necessary to form a bubble increases to a maximum w P-P-=05 -12 r Figure 2. A schematic representatioc of tte work n~eded to form a critical size bubble as a function of bubble radius. On the sa.turated vapor pressure curve, the work ris~s monotonically (curve a). As the liquid is brought into the metastable regio~, the work necessary to form a bubble of radius r first in...

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“…The exact mechanism of this nucleation remains unclear; however several hypotheses had been considered including surface heating by the light, mechanical or phonon effects, and photoelectrons. Each of these hypotheses have been seriously compromised by experimental results and thus there remains the intriguing question of how exactly visible light can cause the nucleation of vapor bubbles in superheated liquid helium (Sinha 1980, Lezak 1984a).…”

Section: Introductionmentioning

confidence: 99%

Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4

Lezak¹

2000

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Synopsis of Recently Submitted PhD Thesis

Cited by 7 publications

References 0 publications

Life history of freshwater populations ofRhizoclonium hieroglyphicum(Cladophorales, Chlorophyta)

Life history of freshwater populations ofRhizoclonium hieroglyphicum(Cladophorales, Chlorophyta)

The Tensile Strength of Liquid Helium Four

Studies of nucleation and heat transfer in liquid helium isotopes 3 and 4

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