Non-standard magnetohydrodynamics equations and their implications in sunspots

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200190
Author(s):  
Rami Ahmad El-Nabulsi
Keyword(s):  
Low Temperature ◽  
Mhd Equations ◽  
Positive Sign ◽  
Magnetic Flux Tube ◽  
Inviscid Fluid ◽  
Interaction Terms ◽  
Conventional Procedure ◽  
Linear Waves ◽  
Mhd Equilibrium ◽  
Alfven Velocity

In this work, we study the physics of plasma waves and magnetohydrodynamic (MHD) equilibrium of sunspots based on the concept of non-standard Lagrangians which play an important role in several branches of science. We derived the modified fluid equations from the Maxwell–Vlasov equation using the moment conventional procedure. Several new interaction terms between physical quantities arise in the non-standard MHD (NS-MHD) equations that give rise to additional features in plasma MHD. A number of fundamental problems in plasma physics are discussed including the non-relativistic dynamics of inviscid fluid subject to the gravitational field, linear waves in plasma MHD and MHD equilibrium of sunspots. For the case of magnetoacoustic wave, it was observed that the NS-MHD equations modify the dispersion relation and its corresponding velocity depends on the sign (positive or negative) of the free parameters introduced in the theory. The non-standard Alfvén velocity is greater than the standard Alfvén velocity for the negative sign and smaller for the positive sign. Besides, in the MHD equilibrium of sunspots, non-standard MHD extends the conventional problem by adding several constraints that lead to an emergence of very low temperature inside the magnetic flux tube comparable to what is observed in low-temperature superconductors. Additional consequences are discussed accordingly.

scholarly journals Validity of the digitonin method for metabolite compartmentation in isolated hepatocytes

1980 ◽  
Vol 188 (1) ◽  
pp. 207-212 ◽  
Author(s):  
D G Brocks ◽  
E A Siess ◽  
O H Wieland
Keyword(s):  
Low Temperature ◽  
Adenine Nucleotides ◽  
Isolated Hepatocytes ◽  
Cell Fractionation ◽  
Conventional Procedure ◽  
Cellular Content ◽  
Temperature Method

1. A modification of the digitonin method of Zuurendonk & Tager (1974) (Biochim. Biophys. Acta 333, 393-399) (i.e. the ‘convaentional’ method) was developed that allows the fractionation of isolated hepatocytes at −5 degrees C (i.e. ‘low-temperature’ method). 2. With respect to compartmentation of adenine nucleotides, glutamate and citrate, the two methods yielded very similar results. 3. In contrast, the mitochondrial amounts of aspartate and malate, as revealed by the low-temperature method, were about twice as high as those found by the conventional procedure. No change in the total cellular content occurred. 4. With n-butylmalonate and glisoxepid present in the conventional digitonin medium, significantly higher amounts of malate and aspartate respectively were found in the mitochondrial pellets. The results obtained by the low-temperature method, however, were not influenced by the these inhibitors. 5. It is concluded that under the conventional conditions of cell fractionation no appreciable redistribution of adenine nucleotides, glutamate and citrate occurs.

Processing and Characterization of Amorphous Copper Oxide Thin Films Prepared by Reactive Magnetron Sputtering

2018 ◽  
Vol 775 ◽  
pp. 238-245 ◽  
Author(s):  
Thitinai Gaewdang ◽  
Ngamnit Wongcharoen
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Magnetron Sputtering ◽  
Copper Oxide ◽  
Flow Rate ◽  
Localized States ◽  
Positive Sign ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Deposited Films

In this paper, copper oxide (CuOx) thin films with amorphous phase were prepared on glass substrates by reactive dc magnetron sputtering. The influence of the flow rate of O2 on the structural, optical and electrical properties of the as-deposited films was systematically studied. XRD revealed that the as-deposited films remained amorphous in the whole range of adjusted oxygen flow rate. Surface morphology and nanoparticle size of the films were observed by AFM. Electrical resistivity and Hall effect measurements were performed on the films with van der Pauw configuration. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. From temperature-dependent electrical conductivity of the films prepared at R(O2) of 1.5 sccm, it was show that three types of behavior can be expected, nearest-neighbor hopping at high temperature range (200-300 K), the Mott variable range hopping at low temperature (110-190 K) and Efros-Shklovskii variable range hopping at very low temperature (65-100 K). Some important parameters corresponding to Mott-VRH and ES-VRH like density of localized states near the Fermi level, localization length, degree of disorder, hopping distance and hopping energy were determined. These parameters would be helpful for optimizing the performance of photovoltaic applications.

scholarly journals Low Beta MHD Equilibrium Including a Static Magnetic Island for Reduced MHD Equations in a Straight Heliotron Configuration

2012 ◽  
Vol 7 (0) ◽  
pp. 1403070-1403070
Author(s):  
Kinya SAITO ◽  
Katsuji ICHIGUCHI ◽  
Ryuichi ISHIZAKI
Keyword(s):  
Mhd Equations ◽  
Magnetic Island ◽  
Mhd Equilibrium

scholarly journals Does Trade Openness Transfer Pollution across Borders: An Experience of Pakistan

2020 ◽  
Vol 6 (2) ◽  
pp. 547-560
Author(s):  
Fareed Shareef ◽  
Imran Sharif Chaudhary ◽  
Toseef Azid ◽  
Muhammad Raza Zafar
Keyword(s):  
Scale Effect ◽  
Trade Openness ◽  
Positive Sign ◽  
Emission Level ◽  
Technique Effect ◽  
Interaction Terms ◽  
Capital Labor Ratio ◽  
Effect Model ◽  
The Relationship ◽  
Scale Composition

The study aims to empirically explore the link between trade openness and emission level in Pakistan by using Johansson co integration technique during the period from1972 to 2019. The empirical strategy of the study progressively incorporates models from zero interaction terms to complete interaction terms for analyzing the relationship between trade openness and emission level in the presence of scale, composition and technique effect. The variable of the trade openness appeared in all the models with negative sign except in scale effect model.  It means technique effect outweighs the composition and scale effect in Pakistan which ultimately makes decreasing impact of trade on pollution. The scale effect results in higher emissions in Pakistan.  Similarly, composition effect also bears positive sign showing that higher capital labor ratio in Pakistan will increase pollution because capital goods are said to be pollution intensive goods.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast

1988 ◽  
Vol 46 ◽  
pp. 256-257
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Eugene L. Vigil
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Standard Specimen ◽  
High Vacuum ◽  
Specimen Holder ◽  
Sputter Coating ◽  
Fresh Frozen ◽  
Gain Access ◽  
Scanning Electron ◽  
Transfer Device

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.

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