Application of Mohr-Westphal Balance to Rapid Calibration of Wide Range Density-Gradient Columns

1952 ◽  
Vol 24 (6) ◽  
pp. 1052-1053 ◽  
Author(s):  
F. M. Richards ◽  
T. E. Thompson
Keyword(s):  
Density Gradient ◽  
Wide Range ◽  
Range Density ◽  
Rapid Calibration

scholarly journals Dependence of Differential Mixing on N and Rρ

2005 ◽  
Vol 35 (6) ◽  
pp. 991-1003 ◽  
Author(s):  
William J. Merryfield
Keyword(s):  
Density Gradient ◽  
Parameter Dependence ◽  
Buoyancy Frequency ◽  
Turbulent Diffusivity ◽  
Ocean Turbulence ◽  
Molecular Diffusivity ◽  
Wide Range ◽  
Gradient Ratio ◽  
Vertical Gradients

Abstract Mechanisms and parameter dependence of differential mixing of heat and salt by ocean turbulence are investigated numerically by extending a previous study to examine dependence upon buoyancy frequency N and density gradient ratio Rρ. In these experiments a burst of turbulence mixes temperature T and pseudosalinity S having molecular diffusivity 0.1 times that of T across background vertical gradients of both quantities. In contrast to previous results, which found turbulent diffusivity ratios d = KS/KT < 1 at a fixed N, the present study finds that d > 1 when N = 0 and that d tends to approach this value as N → 0. In all cases considered, d is larger at high Rρ (buoyancy dominated by T) than at low Rρ (buoyancy dominated by S). It is shown that this tendency is consistent with differential mixing being largely due to preferential restratification of the slower-diffusing component S. This conclusion is reinforced by the finding that d scales linearly with a fractional restratification measure over a wide range of conditions.

Magnetic float densimeter for wide range density measurements

1977 ◽  
Vol 48 (12) ◽  
pp. 1695-1698 ◽  
Author(s):  
Bhajendra Narayan Barman ◽  
Zillur Rahim
Keyword(s):  
Density Measurements ◽  
Wide Range ◽  
Magnetic Float Densimeter ◽  
Range Density ◽  
Magnetic Float

Rotational stabilisation of the Rayleigh–Taylor instability at the inner surface of an imploding liquid shell

2019 ◽  
Vol 873 ◽  
pp. 531-567 ◽  
Author(s):  
Justin Huneault ◽  
David Plant ◽  
Andrew J. Higgins
Keyword(s):  
Density Gradient ◽  
High Speed ◽  
Mode Number ◽  
Cavity Surface ◽  
Convergence Results ◽  
Wide Range ◽  
Inner Surface ◽  
Angular Velocities ◽  
Unstable Cavity ◽  
Rotating Shell

A number of applications utilise the energy focussing potential of imploding shells to dynamically compress matter or magnetic fields, including magnetised target fusion schemes in which a plasma is compressed by the collapse of a liquid metal surface. This paper examines the effect of fluid rotation on the Rayleigh–Taylor (RT) driven growth of perturbations at the inner surface of an imploding cylindrical liquid shell which compresses a gas-filled cavity. The shell was formed by rotating water such that it was in solid body rotation prior to the piston-driven implosion, which was propelled by a modest external gas pressure. The fast rise in pressure in the gas-filled cavity at the point of maximum convergence results in an RT unstable configuration where the cavity surface accelerates in the direction of the density gradient at the gas–liquid interface. The experimental arrangement allowed for visualisation of the cavity surface during the implosion using high-speed videography, while offering the possibility to provide geometrically similar implosions over a wide range of initial angular velocities such that the effect of rotation on the interface stability could be quantified. A model developed for the growth of perturbations on the inner surface of a rotating shell indicated that the RT instability may be suppressed by rotating the liquid shell at a sufficient angular velocity so that the net surface acceleration remains opposite to the interface density gradient throughout the implosion. Rotational stabilisation of high-mode-number perturbation growth was examined by collapsing nominally smooth cavities and demonstrating the suppression of small spray-like perturbations that otherwise appear on RT unstable cavity surfaces. Experiments observing the evolution of low-mode-number perturbations, prescribed using a mode-6 obstacle plate, showed that the RT-driven growth was suppressed by rotation, while geometric growth remained present along with significant nonlinear distortion of the perturbations near final convergence.

scholarly journals Purification and characterization of kynurenine-2-oxoglutarate aminotransferase from the liver, brain and small intestine of rats

1975 ◽  
Vol 151 (2) ◽  
pp. 399-406 ◽  
Author(s):  
T Noguchi ◽  
Y Minatogawa ◽  
E Okuno ◽  
M Nakatani ◽  
M Morimoto ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Small Intestine ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Sucrose Density Gradient Centrifugation ◽  
Ph Optimum ◽  
Wide Range

1. Kynurenine-2-oxoglutarate aminotransferase (isoenzyme 1) was purified to homogeneity from the liver, brain and small intestine of rats by the same procedure. The three enzyme preparations had nearly identical pH optima, substrate specificities and molecular weights. Isoenzyme 1 was active with 2-oxoglutarate but not with pyruvate as amino acceptor, and utilized a wide range of amino acids as amino donors. Amino acids were effective in the following order to activity: L-aspartate greater than L-tyrosine greater than L-phenylalanine greater than L-tryptophan greater than 5-hydroxy-L-tryptophan greater than L-kynurenine. The molecular weight was approximately 88 000 as determined by sucrose-density-gradient centrifugation. The pH optimum was between 8.0 and 8.5. On the basis of substrate specificity, substrate inhibition, subcellular distribution and polyacrylamide-disc-gel electrophoresis, it is suggested that liver, brain and small intestinal kynurenine-2-oxoglutarate aminotransferase (isoenzyme 1) is identical with mitochondrial tyrosine-2-oxoglutarate aminotransferase and also with mitochondrial aspartate-2-oxoglutarate aminotransferase. 2. An additional kynurenine-2-oxoglutarate aminotransferase (isoenzyme 2) was purified from the liver. This enzyme was specific for 2-oxoglutarate and L-kynurenine. Sucrose-density-gradient centrifugation gave a molecular weight of approximately 100 000. The pH optimum was between 6.0 and 6.5. This enzyme was not detected in the brain or small intestine.

CO2 Reduction to Renewable Hydrocarbon Fuel—Mimicking Natural Photosynthesis

MRS Advances ◽  
2017 ◽  
Vol 2 (55) ◽  
pp. 3383-3388
Author(s):  
S. Alfalah ◽  
W.M.I. Hassan ◽  
A. Verma ◽  
N. Al.-Hashimi ◽  
M. M. Khader ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Light Absorption ◽  
Density Functional ◽  
Co2 Reduction ◽  
Visible Spectrum ◽  
Hydrocarbon Fuel ◽  
Functional Theory ◽  
Wide Range ◽  
Natural Photosynthesis ◽  
Range Density

AbstractWe report on a wide-range Density Functional Theory (DFT) investigation of the g-C3N4 photocatalysis systems combined with metals/nonmetals, especially those available in plants and involved in the natural photosynthesis process, such as K, Mg, Mn, Mo, Fe, Co, Cr, S and B. It is found that doping increases the range at which light absorption occurs to significantly large regions of the visible spectrum. These findings suggested that the g-C3N4 can be a promising system for the photosynthesis process.

THE RELATIVE ROLES OF IODINATION AND IODOTHYRONINE CONTENT ON THYROGLOBULIN STABILITY

1975 ◽  
Vol 78 (3) ◽  
pp. 468-480 ◽  
Author(s):  
Hitoshi Fukuda ◽  
Monte A. Greer
Keyword(s):  
Density Gradient ◽  
Acid Composition ◽  
Soluble Protein ◽  
Iodine Content ◽  
Sucrose Density Gradient ◽  
Density Gradient Ultracentrifugation ◽  
Wide Range ◽  
Primary Determinant

ABSTRACT We have independently varied the degree of iodination and of iodothyronine formation over a wide range by acutely administering various doses of perchlorate and/or methimazole to severely iodine-deficient rats 30 min before giving 131I− with graded quantities (1–100 μg of 127I−). Thyroids were removed 4 h later and the soluble protein analyzed for labelled iodoamino acid composition and with sucrose density gradient ultracentrifugation. Since the total thyroid iodine content before administering 127I− was less than 1 μg, calculation of the degree of iodination and iodothyronine content of the labelled Tgb could be made from the known specificity of the injected labelled iodide. Newly organified iodine ranged from < 0.1 to 1.4 μg/thyroid and labelled iodothyronines from < 5 to 962 pmoles/thyroid. Both the degree of iodination and iodothyronine content varied directly with Tgb stability in the absence of inhibitors. But when Tgb iodination was kept constant, Tgb stability at pH 10.1 varied directly with iodothyronine content. When iodothyronine content was kept constant, Tgb stability was independent of the degree of iodination. Correlation of stability with iodothyronine content was highly significant (r = 0.79, P < 0.001) but not of stability with iodine content (r = 0.49, P > 0.05). We conclude that the primary determinant of Tgb stability in mild alkali is the iodothyronine content and not the degree of iodination of the protein. The increased Tgb stability may be induced by coupling between iodotyrosil residues of different 12 S subunits rather than between residues of the same 12 S subunit.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

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