Effect Of Ion Temperature Research Articles

Rational method development strategies on a fluorinated liquid chromatography stationary phase: Mobile phase ion concentration and temperature effects on the separation of ephedrine alkaloids

Fluorinated, silica-based stationary phases are becoming increasingly popular alternatives to traditional alkyl phases owing to their differential selectivity and retention for a variety of analyte classes. In this report, the ion-exchange mechanisms characteristic of a fluorinated phase are exploited to rapidly develop separation conditions for ephedrine alkaloids and synephrine using a mobile phase compatible with mass spectrometry. A linear relationship of basic analyte retention with the reciprocal of ammonium acetate concentration is first established. This linear relationship can then be used to optimize retention and selectivity in just two experiments. The relationship of retention with temperature is also explored. Greater retention with increasing temperature is demonstrated on the fluorinated phase at high percentages of organic modifier, which is in contrast to behavior observed in typical reversed-phase separations. The unexpected observation is explicated based on the reduction in solvent solvating power with increasing temperature. As solvation power of the mobile phase decreases, decreased solvation of both mobile phase and ionized surface groups of the stationary phase leads to stronger interactions between analyte and stationary phase. Both mobile phase ion concentration and temperature are shown to be powerful tools for the manipulation of analyte retention and selectivity.

Studies of the Rate Constant of Levodopa Methyl Ester Hydrolysis by LC

This paper investigates the hydrolysis kinetics of levodopa methyl ester in 0.05–1.5 M HCl between 37 and 75°C. An isocratic HPLC assay was developed for simultaneous determination of levodopa methyl ester and levodopa in the hydrolysate of levodopa methyl ester. A series of hydrolysis rate constants were obtained and the effects of hydrogen ion concentration and temperature on the reaction were evaluated. It was found that pH was a key factor at low temperature, but that when the temperature was raised, temperature became in turn the most influent factor on the hydrolysis. From the measured pseudo-first order reaction rate constants, the activation energy for levodopa methyl ester hydrolysis in 0.5, 1.0 and 1.5 M HCl were calculated to be 71.24, 74.32 and 76.57 kJ mol−1, respectively.

Nonlinear Zakharov–Kuznetsov equation for obliquely propagating two-dimensional ion-acoustic solitary waves in a relativistic, rotating magnetized electron-positron-ion plasma

The purpose of this work is to investigate the linear and nonlinear properties of the ion-acoustic waves (IAW), propagating obliquely to an external magnetic field in a weakly relativistic, rotating, and magnetized electron-positron-ion plasma. The Zakharov–Kuznetsov equation is derived by employing the reductive perturbation technique for this wave in the nonlinear regime. This equation admits the solitary wave solution. The amplitude and width of this solitary wave have been discussed with the effects of obliqueness, relativity, ion temperature, positron concentration, magnetic field, and rotation of the plasma and it is observed that for IAW these parameters affect the propagation properties of solitary waves and these plasmas behave differently from the simple electron-ion plasmas. Likewise, the current density and electric field of these waves are investigated for their dependence on the above-mentioned parameters.

Electron inertia contribution to soliton evolution in an inhomogeneous weakly relativistic two-fluid plasma

The contribution of electron inertia to the evolution of solitons in weakly and strongly inhomogeneous plasmas having streaming ions and electrons with weak relativistic effect is studied on the basis of a relevant Korteweg–de Vries equation derived with the help of reductive perturbation technique. Three types of modes (fast, medium, and slow) are found to propagate in the plasma. In case of weak (strong) inhomogeneous plasma, only the fast (slow) mode corresponds to the soliton evolution. For the propagation of solitons in strongly inhomogeneous plasma, there is no restriction on the ion and electron velocities but in case of weak inhomogeneity the solitons are possible only for a particular range of velocity difference. This range shows the dependence on the temperature and mass ratios of the ions and electrons. In addition, it is realized that only the rarefactive solitons are possible in the present plasma model. The effect of electron inertia on the phase velocity, peak soliton amplitude, and soliton width is studied together with the effects of plasma density, ion temperature, and speeds (relativistic effects) of ions and electrons.

Expansion of a finite plasma into a vacuum

The expansion of a finite plasma into a vacuum is studied both analytically and numerically. The universal solution independent of the initial plasma size is discussed. In the case of cold ions the problem is solved completely. The region where two rarefaction waves interact and its boundaries with the rarefaction waves are described. It is found that the boundaries represent weak discontinuities. The effect of the initial ion temperature on the process is illustrated.

Effect of the ion distribution over longitudinal velocities on the efficiency and separating parameters of the ICR method of isotope separation

In the context of the ICR method of isotope separation, resonance RF heating of the ions in an electric field propagating along a constant magnetic field while simultaneously rotating in the direction perpendicular to it is calculated in a linear approximation. The analysis is carried out for two types of the initial ion distribution function over longitudinal velocities: a function proportional to the first power of the velocity in the range of low velocities and a shifted semi-Maxwellian distribution function. The distribution function of the ions over transverse velocities is calculated under the assumption that their initial distribution over transverse velocities is Maxwellian. The ion fluxes onto the collector plates are estimated by integrating the corresponding ion distribution functions over the allowed range of the longitudinal and transverse velocities and the transverse coordinates of the guiding centers of the ion trajectories in front of the extractor. In the first part of the paper, calculations are carried out for a model binary mixture of isotopes with mass numbers of 6 and 7. The effect of the shape of the ion distribution function over longitudinal velocities on the heating efficiency and on the concentration of the target isotope ions at the collector, as well as the effect of the longitudinal ion temperature on the width of resonance curves for the ion heating efficiency, is investigated. In the second part, a study is made of the selectivity of heating of isotope ions in a gadolinium plasma, in particular, the effect of the longitudinal magnetic field on the selectivity of heating of neighboring isotopes with atomic masses of 156, 157, and 158 is examined.

Electron inertia effect on small amplitude solitons in a weakly relativistic two-fluid plasma

One-dimensional evolution of solitons in a two-fluid plasma having weakly relativistic streaming ions and electrons is studied through usual Korteweg–de Vries equation under the effect of electron inertia. Although fast and slow ion acoustic modes are possible in such a plasma, only the fast mode corresponds to the soliton propagation for a particular range of velocity difference of ions and electrons. This range depends upon the ratios of mass and temperature of the ions and electrons. The effect of electron inertia on the propagation characteristics of the soliton is studied for typical values of the speed and temperature of the ions and electrons and it is found that this effect is dominant over the relativistic effect and the effect of ion temperature.

Dust-ion-acoustic solitary waves in a hot magnetized dusty plasma with charge fluctuations

The effects of dust grain charge fluctuation, dust temperature, ion temperature, obliqueness and external magnetic field on the nonlinear properties of dust-ion-acoustic (DIA) solitary waves are studied in a hot magnetized dusty plasma consisting of a negatively charged, extremely massive hot dust fluid, positively charged hot ion fluid and vortex-like distributed electrons. A modified Korteweg de Vries equation (mKdV), which admits a solitary wave solution for small but finite amplitude is derived using a reductive perturbation theory. The numerical results are applied to Saturn’s F-ring.

Effects of positron concentration, ion temperature, and plasma β value on linear and nonlinear two-dimensional magnetosonic waves in electron–positron–ion plasmas

Magnetosonic waves are intensively studied due to their importance in space plasmas and also in fusion plasmas where they are used in particle acceleration and heating experiments. This work considers magnetosonic waves propagating obliquely at an angle θ to an external magnetic field in an electron–positron–ion plasma, using the effective one-fluid magnetohydrodynamic model. Two separate modes (fast and slow) for the waves are discussed in the linear approximation, and the Kadomstev–Petviashvilli soliton equation is derived by using reductive perturbation scheme for these modes in the nonlinear regime. It is observed that for both the modes the angle θ, positron concentration, ion temperature, and plasma β-value affect the propagation properties of solitary waves and behave differently from the simple electron–ion plasmas. Likewise, current density, electric field, and magnetic field for these waves are investigated, for their dependence on the above mentioned parameters.

Effects of seawater carbonate ion concentration and temperature on shell U, Mg, and Sr in cultured planktonic foraminifera

We investigate the sensitivity of U/Ca, Mg/Ca, and Sr/Ca to changes in seawater [CO 3 2−] and temperature in calcite produced by the two planktonic foraminifera species, Orbulina universa and Globigerina bulloides, in laboratory culture experiments. Our results demonstrate that at constant temperature, U/Ca in O. universa decreases by 25 ± 7% per 100 μmol [CO 3 2−] kg −1, as seawater [CO 3 2−] increases from 110 to 470 μmol kg −1. Results from G. bulloides suggest a similar relationship, but U/Ca is consistently offset by ∼+40% at the same environmental [CO 3 2−]. In O. universa, U/Ca is insensitive to temperature between 15°C and 25°C. Applying the O. universa relationship to three U/Ca records from a related species, Globigerinoides sacculifer, we estimate that Caribbean and tropical Atlantic [CO 3 2−] was 110 ± 70 μmol kg −1 and 80 ± 40 μmol kg −1 higher, respectively, during the last glacial period relative to the Holocene. This result is consistent with estimates of the glacial–interglacial change in surface water [CO 3 2−] based on both modeling and on boron isotope pH estimates. In settings where the addition of U by diagenetic processes is not a factor, down-core records of foraminiferal U/Ca have potential to provide information about changes in the ocean’s carbonate concentration. Below ambient pH (pH < 8.2), Mg/Ca decreased by 7 ± 5% ( O. universa) to 16 ± 6% ( G. bulloides) per 0.1 unit increase in pH. Above ambient pH, the change in Mg/Ca was not significant for either species. This result suggests that Mg/Ca-based paleotemperature estimates for the Quaternary, during which surface-ocean pH has been at or above modern levels, have not been biased by variations in surface-water pH. Sr/Ca increased linearly by 1.6 ± 0.4% per 0.1 unit increase in pH. Shell Mg/Ca increased exponentially with temperature in O. universa, where Mg/Ca = 0.85 exp (0.096*T), whereas the change in Sr/Ca with temperature was within the reproducibility of replicate measurements.

The effects of ion temperature on dust charging in the sheath of dusty plasmas

Dust charging in the sheath is investigated with the single dust model. The sheath profile and variation of dust charge are revealed under the effect of ion temperature. It is shown that the dust particles are rapidly positively charged in the pure ion sheath near the wall and that the ion motion effectively shifts the zero-point of the dust charge to the wall.

Relation between Hall-magnetohydrodynamics and the kinetic Alfvén wave

Effects of a finite ion temperature on the Hall magnetohydrodynamics (MHD), which breaks down for a finite ion temperature, are clarified in terms of a rigorous three-field kinetic dispersion relation. The MHD mode equation becomes anisotropic with respect to the ion pressure because of the double adiabaticity in ion dynamics.

Dust-acoustic solitary waves in a finite temperature dusty plasma with variable dust charge and two temperature ions

In this paper, the characteristics of dust-acoustic solitary waves in dusty plasma are studied. Dust charge and temperature are treated as variables. The authors have used the pseudopotential method to investigate the possibility of compressive as well as rarefactive solitons. An expression for the pseudopotential has been derived. The pseudopotential is a function of the Mach number, the relative temperature of low and high ion components, the relative ion concentration of dust charge and the temperature. Numerical computation shows that for the chosen set of parameters, only compressive solitons exist and their amplitudes increase with increasing Mach number. An increase in the dust temperature results in the disappearance of the compressive soliton. It is the only small parameter regime where compressive as well rarefactive solitons coexist. The effect of the relative ion temperature on solitons is also investigated. In the small amplitude limit, an increase in the dust temperature leads to a transition from compressive to rarefactive solitons.

Small amplitude Bernstein–Greene–Kruskal solitary waves in a thermal charge-varying dusty plasma

Small amplitude electrostatic solitary Bernstein–Greene–Kruskal (BGK) waves are investigated in an unmagnetized thermal charge-varying dusty plasma. The well-known pseudopotential analysis is used. It is found that under certain conditions spatially localized structures, the height and nature of which depend sensitively on the plasma parameters, can exist. The effects of ion temperature, equilibrium dust charge, dust dynamics, and dust size on the properties of these solitary waves are discussed. This investigation may be taken as a prerequisite for the understanding of the solitary dust BGK waves that may occur in space and laboratory plasmas.

Uptake of the carborane derivative of cholesteryl ester by glioma cancer cells is mediated through LDL receptors.

This study was to elucidate the mechanism of cellular uptake of cholesteryl 1,12-dicarba-closo-dodecaboranel-carboxylate (BCH), a new anti-cancer carborane derivative of cholesteryl ester, by glioma cancer cells. BCH (solubilized with liposomal formulation) was incubated with SF-763 and SF-767 glioma cell lines in the presence of different amounts of monoclonal anti-LDL receptor antibody for cellular uptake studies. Various amounts of lipoprotein deficient serum (LPDS) were also used during the uptake. The effect of calcium ion and low temperature on BCH uptake were investigated. In addition, the transfer of BCH from liposomes to low-density lipoprotein (LDL) particles was determined through gradient ultracentrifugation. BCH uptake by these glioma cells was significantly inhibited by the monoclonal antibody. The uptake by both cell lines was reversely correlated with the amount of LPDS. The presence of calcium ion promoted the BCH uptake, whereas the low temperature decreased the BCH uptake. After 16 h incubation, about 46% of BCH was transferred from liposomes to LDL particles. These results strongly suggested that the cellular uptake of BCH (in liposomal formulation) by SF-763 and SF-767 glioma cell lines is mediated through LDL receptors.

Zonal flow and field generation by finite β drift waves: Finite ion temperature effects

The generation of zonal flows and zonal fields by finite β drift waves in plasmas with finite ion temperature Ti is investigated. This work extends our earlier work with zero ion temperature. The growth rate of the zonal flow and field is enhanced by finite Ti effects. This leads to a reduction in the critical electron temperature derived earlier for triggering low to high transitions in tokamak plasmas.

Ion temperature and plasma rotation profile effects in the neutron emission spectrum

The instrumental factors and measuring conditions affecting neutron emission spectrometry measurements of tokamak plasmas are described and analyzed. The measured energy broadening and shift of the neutron emission is used to deduce ion temperature (Ti) and toroidal plasma rotation velocity (Vt) representing average (effective) values for the nonuniform plasma volume viewed. Analytical expressions are derived for the relationship between the line-volume integrated effective temperature (Teff) and the radial profile Ti(r) for the case of thermal plasmas with isotropic neutron emission; effects on Teff due to spectral broadening from the radial dependence Vt(r) were also considered. The analysis method presented here is applied to high quality data obtained with the magnetic proton recoil neutron spectrometer installed at Joint European Torus for measurements of deuterium–tritium plasmas. Similarly, cases of anisotropic neutron emission were quantitatively assessed.

Biosorption of Cadmium by Fucus spiralis

Environmental Context. Conventional processes for the removal of heavy metals from wastewaters generally involves chemical precipitation of metals (changing the pH) followed by a period to allow the metal precipitates to settle and be separated. These processes are inefficient when the metals are at a low concentration and still demand handling and disposal of toxic metal sludges. An alternative method for heavy metal removal is adsorption onto a biological material, biosorption. The biological materials, including agricultural byproducts, bacteria, fungi, yeast, and algae, all which take up heavy metals in substantial quantities, are relatively inexpensive, widely available, and from renewable sources. However, biological materials are complex and the active mechanisms often unclear. Abstract. Cadmium biosorption properties of nonliving, dried brown marine macroalga Fucus spiralis from Galician coast (northwest Spain) have been investigated. The biosorption capacity of the alga strongly depends on solution pH; the uptake is almost negligible at pH ≤ 2 and reaches a plateau at around pH 4.0. Cadmium biosorption kinetics by F. spiralis is relatively fast, with 90% of total adsorption taking place in less than one hour. A pseudo second order mechanism has been proved to be able to predict the kinetic behaviour of the biosorption process. The effect of initial cadmium ion concentration, alga dose, solution pH, and temperature on the biosorption kinetics has been studied. The Langmuir, Freundlich, Langmuir–Freundlich, and Tóth isotherms were used to fit the experimental data and to find out the adsorption parameters. Acid–base properties of the alga have been studied potentiometrically in order to calculate the number of acidic groups and the apparent pK value by using Katchalsky model. The pK obtained is comparable with typical values associated to the ionization of carboxyl groups of alginates, supporting the implication of these groups in the biosorption process.

511 サーマルプローブを用いたイオン温度計測の新しいアプローチ(GS-6 液滴・計測)

Plasma is generally in the non-thermal equibilium, and its components, ion and electron, have different temperatures. Though Langmuir probe method is widely used to measure electorn temperature, ion temperature is difficult to deduce with it. In this paper, we propose the thermal probe as a new tool for ion temperature measurement. Firstly the effect of finite ion temperature onto analytical heat flux formula in the sheath theory. Then the procedure to deduce the ion temperature from heat flux data is presented. Finally we make a prototype of the thermal probe and test it with the glow discharge plasma.

Finite ion temperature effects on oblique modulational stability and envelope excitations of dust-ion acoustic waves

Theoretical and numerical investigations are carried out for the amplitude modulation of dust-ion acoustic waves (DIAW) propagating in an unmagnetized weakly coupled collisionless fully ionized plasma consisting of isothermal electrons, warm ions and charged dust grains. Modulation oblique (by an angle $\theta$ ) to the carrier wave propagation direction is considered. The stability analysis, based on a nonlinear Schrodinger-type equation (NLSE), exhibits a sensitivity of the instability region to the modulation angle $\theta$ , the dust concentration and the ion temperature. It is found that the ion temperature may strongly modify the wave’s stability profile, in qualitative agreement with previous results, obtained for an electron-ion plasma. The effect of the ion temperature on the formation of DIAW envelope excitations (envelope solitons) is also discussed.