Electron-Alkali Scattering and Photodetachment of Alkali Negative Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

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Mass-resolved electronic circular dichroism ion spectroscopy

Science ◽

10.1126/science.abb1822 ◽

2020 ◽

Vol 368 (6498) ◽

pp. 1465-1468 ◽

Cited By ~ 7

Author(s):

Steven Daly ◽

Frédéric Rosu ◽

Valérie Gabelica

Keyword(s):

Circular Dichroism ◽

Three Dimensional ◽

Polarized Light ◽

Negative Ions ◽

Data Interpretation ◽

Electronic Circular Dichroism ◽

Circularly Polarized Light ◽

Chiral Compounds ◽

Electron Photodetachment ◽

Circular Dichroïsm

DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet nanosecond optical parametric oscillator laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resembled those of their solution-phase counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.

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Effect of Low-Pressure Plasma Treatment Parameters on Wrinkle Features

Materials ◽

10.3390/ma13173852 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3852

Author(s):

Bongjun Gu ◽

Dongwook Ko ◽

Sungjin Jo ◽

Dong Choon Hyun ◽

Hyeon-Ju Oh ◽

...

Keyword(s):

Power Flow ◽

Treatment Time ◽

Argon Plasma ◽

Negative Ions ◽

Low Pressure ◽

Nitrogen Plasma ◽

Pressure Plasma ◽

Positive Ions ◽

Low Pressure Plasma ◽

Optical Adhesive

Wrinkles attract significant attention due to their ability to enhance the mechanical and optical characteristics of various optoelectronic devices. We report the effect of the plasma gas type, power, flow rate, and treatment time on the wrinkle features. When an optical adhesive was treated using a low-pressure plasma of oxygen, argon, and nitrogen, the oxygen and argon plasma generated wrinkles with the lowest and highest wavelengths, respectively. The increase in the power of the nitrogen and oxygen plasma increased the wavelengths and heights of the wrinkles; however, the increase in the power of the argon plasma increased the wavelengths and decreased the heights of the wrinkles. Argon molecules are heavier and smaller than nitrogen and oxygen molecules that have similar weights and sizes; moreover, the argon plasma comprises positive ions while the oxygen and nitrogen plasma comprise negative ions. This resulted in differences in the wrinkle features. It was concluded that a combination of different plasma gases could achieve exclusive control over either the wavelength or the height and allow a thorough analysis of the correlation between the wrinkle features and the characteristics of the electronic devices.

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Soliton turbulence in electronegative plasma due to head-on collision of multi solitons

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0186 ◽

2020 ◽

Vol 75 (12) ◽

pp. 999-1007

Author(s):

Rustam Ali ◽

Anjali Sharma ◽

Prasanta Chatterjee

Keyword(s):

Wave Field ◽

Soliton Solutions ◽

Negative Ions ◽

First Integral ◽

Statistical Properties ◽

Charged Dust ◽

Bilinear Method ◽

Electronegative Plasma ◽

Kdv Equations ◽

First Four Moments

AbstractHead-on interaction of four dust ion acoustic (DIA) solitons and the statistical properties of the wave field due to head-on interaction of solitons moving in opposite direction is studied in the framework of two Korteweg de Vries (KdV) equations. The extended Poincaré–Lighthill–Kuo (PLK) method is applied to obtain two opposite moving KdV equations from an unmagnetized four component plasma model consisting of Maxwellian negative ions, cold mobile positive ions, κ-distributed electrons and positively charged dust grains. Hirota’s bilinear method is adopted to obtain two-soliton solutions of both the KdV equations and accordingly act of soliton turbulence is presented due to head-on collision of four solitons. The amplitude and shape of the resultant wave profile at the point of strongest interaction are obtained. To see the effect of head-on collision on the statistical properties of wave field the first four moments are computed. It is observed that the head-on collision has no effect on the first integral moment while the second, third and fourth moments increase in the dominant interaction region of four solitons, which is a clean indication of soliton turbulence.

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Solitary waves in a dusty adiabatic electronegative plasma

Journal of Plasma Physics ◽

10.1017/s0022377809990614 ◽

2010 ◽

Vol 76 (3-4) ◽

pp. 409-418 ◽

Cited By ~ 7

Author(s):

A. A. MAMUN ◽

K. S. ASHRAFI ◽

M. G. M. ANOWAR

Keyword(s):

Solitary Waves ◽

Vries Equation ◽

Negative Ions ◽

Finite Amplitude ◽

Reductive Perturbation Method ◽

Charged Dust ◽

Electronegative Plasma ◽

Ion Acoustic ◽

Basic Features ◽

Electronegative Plasmas

AbstractThe dust ion-acoustic solitary waves (SWs) in an unmagnetized dusty adiabatic electronegative plasma containing inertialess adiabatic electrons, inertial single charged adiabatic positive and negative ions, and stationary arbitrarily (positively and negatively) charged dust have been theoretically studied. The reductive perturbation method has been employed to derive the Korteweg-de Vries equation which admits an SW solution. The combined effects of the adiabaticity of plasma particles, inertia of positive or negative ions, and presence of positively or negatively charged dust, which are found to significantly modify the basic features of small but finite-amplitude dust-ion-acoustic SWs, are explicitly examined. The implications of our results in space and laboratory dusty electronegative plasmas are briefly discussed.

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Effect of External Charging on Nanoparticle Formation in a Flame

Materials ◽

10.3390/ma14112891 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2891

Author(s):

Elena Fomenko ◽

Igor Altman ◽

Igor E. Agranovski

Keyword(s):

Negative Ions ◽

Formation Processes ◽

Particle Charge ◽

Mgo Nanoparticles ◽

Nanoparticle Formation ◽

Noticeable Change ◽

Nanoparticle Shape ◽

Positive Ions ◽

Direct Interpretation ◽

Shape Of Nanoparticles

This paper attempts to demonstrate the importance of the nanoparticle charge in the synthesis flame, for the mechanism of their evolution during formation processes. An investigation was made of MgO nanoparticles formed during combustion of magnesium particles. The cubic shape of nanoparticles in an unaffected flame allows for direct interpretation of results on the external flame charging, using a continuous unipolar emission of ions. It was found that the emission of negative ions applied to the flame strongly affects the nanoparticle shape, while the positive ions do not lead to any noticeable change. The demonstrated effect emphasizes the need to take into account all of the phenomena responsible for the particle charge when modeling the nanoparticle formation in flames.

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Electrostatic wave breaking limit in a cold electronegative plasma with non-Maxwellian electrons

Scientific Reports ◽

10.1038/s41598-021-85228-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

I. S. Elkamash ◽

I. Kourakis

Keyword(s):

Wave Breaking ◽

Density Ratio ◽

Negative Ions ◽

First Integral ◽

Energy Balance Equation ◽

Plasma Parameters ◽

Ion Density ◽

Electrostatic Wave ◽

Nonthermal Electrons ◽

Electronegative Plasma

AbstractA one-dimensional multifluid hydrodynamic model has been adopted as basis for an investigation of the role of suprathermal electrons on the wave breaking amplitude limit for electrostatic excitations propagating in an electronegative plasma. A three-component plasma is considered, consisting of two inertial cold ion populations of opposite signs, evolving against a uniform background of (non-Maxwellian) electrons. A kappa-type (non-Maxwellian) distribution function is adopted for the electrons. By employing a traveling wave approximation, the first integral for the fluid-dynamical system has been derived, in the form of a pseudo-energy balance equation, and analyzed. The effect of intrinsic plasma parameters (namely the ion density ratio, the ion mass ratio, and the superthermal index of the nonthermal electrons) on the wave breaking amplitude limit is explored, by analyzing the phase space topology of the associated pseudopotential function. Our results are relevant to particle acceleration in Space environments and to recent experiments based on plasma-based accelerator schemes, where the simultaneous presence of negative ions and nonthermal electrons may be observed.

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Antibacterial Peptides Produced by Alcalase from Cowpea Seed Proteins

Antibiotics ◽

10.3390/antibiotics10070870 ◽

2021 ◽

Vol 10 (7) ◽

pp. 870

Author(s):

Ali Osman ◽

Gamal Enan ◽

Abdul-Raouf Al-Mohammadi ◽

Seham Abdel-Shafi ◽

Samar Abdel-Hameid ◽

...

Keyword(s):

Size Exclusion Chromatography ◽

Seed Proteins ◽

Negative Ions ◽

Size Exclusion ◽

Ionization Mass ◽

Bacterial Cells ◽

Antibacterial Efficiency ◽

Exclusion Chromatography ◽

Molecular Masses ◽

Cowpea Seed

Cowpea seed protein hydrolysates (CPH) were output from cowpea seeds applying alcalase® from Bacillus licheniformis. CPH with an elevated level of hydrolysis was fractionated by size exclusion chromatography (SEC). Both CPH and SEC-portions showed to contain antimicrobial peptides (AMPs) as they inhibited both Gram-positive bacteria, such as Listeria monocytogenes LMG10470 (L. monocytogenes), Listeria innocua. LMG11387 (L. innocua), Staphylococcus aureus ATCC25923 (S.aureus), and Streptococcus pyogenes ATCC19615 (St.pyogenes), and Gram-negative bacteria, such as Klebsiella pnemoniae ATCC43816 (K. pnemoniae), Pseudomonas aeroginosa ATCC26853 (P. aeroginosa), Escherichia coli ATCC25468) (E.coli) and Salmonella typhimurium ATCC14028 (S. typhimurium).The data exhibited that both CPH and size exclusion chromatography-fraction 1 (SEC-F1) showed high antibacterial efficiency versus almost all the assessed bacteria. The MIC of the AMPs within SEC-F1 and CPHs were (25 µg/mL) against P. aeruginosa, E.coli and St. pyogenes. However, higher MICsof approximately 100–150 µg/mL showed for both CPHs and SEC-F1 against both S. aureus and L. innocua; it was 50 µg/mL of CPH against S.aureus. The Electro-spray-ionization-mass-spectrometry (ESI-MS) of fraction (1) revealed 10 dipeptides with a molecular masses arranged from 184 Da to 364 Da and one Penta peptide with a molecular mass of approximately 659 Da inthe case of positive ions. While the negative ions showed 4 dipeptides with the molecular masses that arranged from 330 Da to 373 Da. Transmission electron microscope (TEM) demonstrated that the SEC-F1 induced changes in the bacterial cells affected. Thus, the results suggested that the hydrolysis of cowpea seed proteins by Alcalase is an uncomplicated appliance to intensify its antibacterial efficiency.

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