scholarly journals Computational and Experimental Studies on the Inhibitive Effects of Newbouldia laevis Extract and Magnetic Fields on Copper Corrosion in Aqueous Acidic Media

2015 ◽  
Vol 54 ◽  
pp. 135-142 ◽  
Author(s):  
B. Okeoma Kelechukwu
Keyword(s):  
Magnetic Fields ◽  
Room Temperature ◽  
Inhibition Efficiency ◽  
Experimental Studies ◽  
Distilled Water ◽  
Copper Corrosion ◽  
Emery Paper ◽  
Inhibition Process ◽  
A Charge ◽  
The Magnetic Field

A ploycrystaline copper (99.99%) coupons of dimension 1x2x5 cm in which a hole of diameter 0.5cm drilled was used. Before all measurements, the coupons were polished successively with metallographic emery paper between (600 and 1200) grits, then washed with doubly distilled water, degreased with acetone and again washed using distilled water and finally allowed to dry in air at room temperature. Explanation of the effects of magnetic fields on inhibition process using the chemical quantum calculations. The dipole moment is the product of a charge and distance of separation of the charges in an atom or molecule. Any process which can cause change in the alignment of the dipoles on the surface of the corroding metal systems can facilitate an increase in inhibition process. The magnetic field acts on the dipoles such that it aligns the charges on the metal thereby providing the needed charge types at the required point. This explains the graph on figure 1 which shows an increase in inhibition efficiency in the presence of magnetic fields.

scholarly journals Generation of strong magnetic fields with a laser-driven coil

2018 ◽  
Vol 6 ◽  
Author(s):  
Zhe Zhang ◽  
Baojun Zhu ◽  
Yutong Li ◽  
Weiman Jiang ◽  
Dawei Yuan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Experimental Studies ◽  
Diagnostic Techniques ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Research Fields ◽  
Laser Facility ◽  
Spatio Temporal ◽  
The Magnetic Field

As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko XII laser facility with a capacitor–coil target. A similar approach has been adopted in a number of laboratories, with a variety of targets of different shapes. The peak strength of the magnetic field varies from a few tesla to kilotesla, with different spatio-temporal ranges. The differences are determined by the target geometry and the parameters of the incident laser. Here we present a review of the results of recent experimental studies of laser-driven magnetic field generation, as well as a discussion of the diagnostic techniques required for such rapidly changing magnetic fields. As an extension of the magnetic field generation, some applications are discussed.

MAGNETORESISTANCE AND FIELD DEPENDENCE OF THE HALL EFFECT IN INDIUM ANTIMONIDE

1958 ◽  
Vol 36 (5) ◽  
pp. 527-538 ◽  
Author(s):  
Gaston Fischer ◽  
D. K. C. MacDonald
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Field Dependence ◽  
Indium Antimonide ◽  
Charge Carriers ◽  
Band Theory ◽  
Hall Effect Measurements ◽  
A Charge ◽  
The Magnetic Field

Magnetoresistance and Hall-effect measurements in InSb are described. This semiconductor has charge carriers with sufficiently long mean free paths, l, that it is possible, even at room temperature and with available magnetic fields, to obtain l/r values considerably greater than unity, r being the orbital radius of a charge carrier moving in the applied magnetic field. The classical two-band theory has been found to account rather well for the results up to the highest magnetic fields employed. A review of the underlying assumptions of this theory is presented, and simple formulae are derived which allow the concentrations and mobilities of both types of carriers to be calculated from the magnetic field dependence of the resistivity, ρH, and of the Hall-constant, AH. The parameter Λ ≡ [(AH−A0)/A0]/[(ρH−ρ0)/ρ0] provides a useful means to check the consistency of the theory and can give some indication of the variation of the mobilities with the magnetic field.

scholarly journals Conocarpus Erectus Extract as an Eco-Friendly Corrosion Inhibitor for Aluminum in Hydrochloric Acid Solution

2020 ◽  
Vol 11 (3) ◽  
pp. 10325-10340
Keyword(s):  
Corrosion Inhibitor ◽  
Inhibition Efficiency ◽  
Adsorption Process ◽  
Experimental Studies ◽  
Outcome Data ◽  
Conocarpus Erectus ◽  
Green Corrosion Inhibitor ◽  
Inhibition Process ◽  
Surface Examination ◽  
Scanning Electron

Conocarpus Erectus extract was examined as a green corrosion inhibitor for Al in 1 M HCl and evaluated by different methods (chemical & electrochemical methods). Surface checks were used to illustrate the importance of this green extract to Al's corrosion inhibition process. The inhibition efficiency (%IE) increased with the raising of both Conocarpus Erectus extract dose and temperature, indicating that this extract was adsorbed chemically on Al surface. The %IE was 91.1% when the concentration Conocarpus Erectus extract was 300 ppm. Conocarpus Erectus extract inhibits both anodic and cathodic reactions, so it is a mixed kind inhibitor. The %IE of Al occurs by the adsorption process, and this metal is subject to the adsorption, according to Temkin isotherm. The surface examination was detected by utilizing a scanning electron microscope (SEM). The outcome data obtained from all experimental studies are excellent and proved the effectiveness of Conocarpus Erectus extract for Al's corrosion resistance.

scholarly journals The change of electrical conductivity in strong magnetic fields. Part I. —Experimental results

1929 ◽  
Vol 123 (791) ◽  
pp. 292-341 ◽  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Magnetic Fields ◽  
Room Temperature ◽  
Linear Part ◽  
Strong Magnetic Fields ◽  
Other Substances ◽  
Different Temperatures ◽  
Weak Fields ◽  
The Magnetic Field

In a recent paper the author described experiments on the change of resistance of bismuth crystals in magnetic fields up to 300,000 gauss. In agreement with previous investigators it was found that the resistance of bismuth in weak fields increases in proportion to the square of the magnetic field, and in stronger fields follows a linear law, the increase of resistance being proportional to the magnetic field up to fields of 300 kilogauss. It was further found that this linear part of the change of resistance is, in most cases, independent of the orientation of the crystal in the magnetic field, and also of the degree of perfection of the crystal. This suggests that we are concerned with an atomic phenomenon. On studying several other substances it was found that the increase of resistance, although on a much smaller scale, is similar to that observed in bismuth, following first the square law and in fields above 60 to 100 kilogauss a linear law. This has led to a systematic study of the elements throughout the periodic table. About 35 different metals have been investigated at different temperatures, varying from room temperature to the temperature of liquid nitrogen, and the law of change of resistance mentioned above is found to be general for all.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

scholarly journals An 84-μG Magnetic Field in a Galaxy at Z=0.692?

2008 ◽  
Vol 4 (S254) ◽  
pp. 95-96
Author(s):  
Arthur M. Wolfe ◽  
Regina A. Jorgenson ◽  
Timothy Robishaw ◽  
Carl Heiles ◽  
Jason X. Prochaska
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Large Scale ◽  
Dynamo Model ◽  
Magnetic Field Generation ◽  
Interstellar Gas ◽  
Splitting Technique ◽  
Average Value ◽  
The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

Magnetic Field Spectroheliograms from the San Fernando Observatory

1971 ◽  
Vol 43 ◽  
pp. 329-339 ◽  
Author(s):  
Dale Vrabec
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spiral Structure ◽  
Longitudinal Component ◽  
Solar Telescope ◽  
Solar Magnetic Fields ◽  
San Fernando ◽  
Field Lines ◽  
The Magnetic Field ◽  
Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

scholarly journals The Origin and Dynamical Effects of the Magnetic Fields and Cosmic Rays in the Disk of the Galaxy

1970 ◽  
Vol 39 ◽  
pp. 168-183
Author(s):  
E. N. Parker
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Dynamical Behavior ◽  
Cosmic Ray ◽  
Interested Reader ◽  
Written Text ◽  
The Galaxy ◽  
Basic Ideas ◽  
The Magnetic Field

The topic of this presentation is the origin and dynamical behavior of the magnetic field and cosmic-ray gas in the disk of the Galaxy. In the space available I can do no more than mention the ideas that have been developed, with but little explanation and discussion. To make up for this inadequacy I have tried to give a complete list of references in the written text, so that the interested reader can pursue the points in depth (in particular see the review articles Parker, 1968a, 1969a, 1970). My purpose here is twofold, to outline for you the calculations and ideas that have developed thus far, and to indicate the uncertainties that remain. The basic ideas are sound, I think, but, when we come to the details, there are so many theoretical alternatives that need yet to be explored and so much that is not yet made clear by observations.

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