Various Degrees Of Ionization Research Articles

Effective enhancement of poly(bisphenol-A carbonate) crystallinity with polyamide-66 ionized nucleation through ion-dipole interactions coupled with plasticization

To improve the crystallinity of poly(bisphenol-A carbonate) (PC). Polyamide-66 (PA-66) is ionized by CaCl2 to prepare the various degrees of ionization (DIs) of PA-66 ionenes (CaCl2–PA-66) as nucleating agents to co-modify PC with cholesterol nonanoate (CN) as plasticizers. Compared with non-ionized PA-66, CaCl2–PA-66 enhance the crystallinity of PC. Concretely, with the DI of CaCl2–PA-66 is raised from 0 to 37.2 mol%, the crystallinity of PC/CN/CaCl2–PA-66 (90/5/5 w/w/w) is first increased from 19.2% to 31.5% and then decreased to 16.9%. This is attributed to the stronger ion-dipole interactions between the ionized nucleating agents and PC, which enhance the compatibility and further dispersibility to create finer crystal with a denser distribution, and the nucleation efficiency is elevated thus facilitating the PC crystallization. However, when the DI of CaCl2–PA-66 is overly high (≥11.4 mol%), it leads to excessive ionic crosslinking, which reduces dispersibility and nucleation efficiency. Therefore, the modification of PC with a suitable DI of CaCl2–PA-66 can advance its crystallinity, which is a novel and effective approach.

Predicting Hepatic Clearance of Psychotropic Drugs in Isolated Perfused Fish Livers Using a Combination of Two In Vitro Assays.

In vitro biotransformation assays with primary trout hepatocytes (RT-HEP) or liver subcellular fractions (RT-S9) have been proposed as valuable tools to help scientists and regulators better understand the toxicokinetics of chemicals. While both assays have been applied successfully to a diversity of neutral organic chemicals, only the RT-S9 assay has been applied to a large number of ionizable organic chemicals. Here, a combination of an in vitro biotransformation assay with RT-HEP with an active transport assay based on the permanent rainbow trout liver cell line RTL-W1 was used to qualitatively predict the potential hepatic clearance of nine psychotropic drugs with various degrees of ionization. Predictions were compared with rates of clearance measured in isolated perfused rainbow trout livers, and the importance of active transport was verified in the presence of the active transport inhibitor cyclosporin A. For the first time, it was demonstrated that a combination of biotransformation and active transport assays is powerful for the prediction of rates of hepatic clearance of ionizable chemicals. Ultimately, it is expected that this approach will allow for use of fewer animals while at the same time improving our confidence in the use of data from in vitro assays in chemical risk assessment.

Liquid Co-crystals of Dual-Active Phenothiazine-NSAID Drugs: Synthesis, Spectroscopic, and Thermal Characterization.

Four aliphatic phenothiazine cations (promazinium, promethazinium, chlorpromazinium, and triflupromazinium) were each paired with docusate anions and three different NSAID anions (ibuprofen, salicylate, and naproxen) to form fifteen glassy materials and one solid. The compounds were prepared via the metathesis reaction between the corresponding phenothiazine hydrochloride salts and sodium docusate or sodium NSAID salts and were obtained as liquid co-crystals with various degrees of ionization. The self-diffusion coefficients of several derivatives in 0.06 M DMSO-d6 solutions were determined using DOSY NMR spectroscopy. The influence of the size, shape of the compounds, and intermolecular forces has been investigated by using the four promazine and the four ibuprofen co-crystals. The ion pairs (or aggregates) were found to be maintained in six out of the seven compounds examined. All fifteen glassy compounds showed reversible glass transitions in the −25 to 10 °C range with the docusate derivatives exhibiting the highest thermal stability (Tonset values being at least 40 °C higher than those of the corresponding phenothiazine hydrochlorides).

Properties of Mixed Aqueous Solutions of Polyethylene Oxide and Carboxymethyl Cellulose with Different Degrees of Ionization and of Composite Films Prepared from Them

Rheological properties of mixtures of dilute and moderately concentrated aqueous solutions of carboxymethyl cellulose with various degrees of ionization and polyethylene oxide were studied. The range of compositions in which the viscosity of dilute solutions of the polymer blends shows negative deviation from the calculated additive values becomes broader in going from carboxymethyl cellulose sodium salt to partially ionized carboxymethyl cellulose. In concentrated mixed polymer solutions, the deviation of the viscosity from the additive values is always positive. Film composite materials were prepared, and their structural organization and compatibility of the polymers in the solid state were studied by dynamic mechanical analysis and X-ray diffraction analysis. Carboxymethyl cellulose with various degrees of ionization is incompatible with polyethylene oxide in the composite films obtained, and no new mixed structures are formed. Polyethylene oxide behaves as an interstructural plasticizer of the cellulose ether.

Diagnostic of a Solar Flare via Analyses of Emission in Spectral Lines of Highly Ionized Iron

An analysis of the dynamics of the electron temperature of the solar atmosphere in regions where solar flares appear is presented. The temperatures are estimated from the emission in spectral lines of ions with various degrees of ionization. The emission of ionized helium and highly ionized iron was used. Images of preflare states and of flares from the archive of the American SDO spacecraft are analyzed. A solar flare is usually preceded by the registration of a bright glowing structure above the action region, with a temperature exceeding that of the corona. This preflare structure (~1010 cm) is identified with the development of a system of currents, which, according to numerical simulations, is responsible for the accumulation of energy above the active region before the flare. After several tens of hours of a slow increase in the brightness of the preflare glow in the 94 A iron (FeXVIII) line, the emission in the 193 A line of FeXXIV increases sharply, indicating a flare-like growth of the temperature up to at least 20 MK. This growth of the emission coincides with the onset of the solar flare. The observed dynamics of the emission in spectral lines of highly ionized ions is consistent with an electrodynamic model of a solar flare based on the accumulation of magnetic energy in a current sheet above the active region and the explosive release of the stored energy. Studies of mechanisms for solar flares are of special importance in connection with the discovery of solar cosmic rays. Information from the worldwide network of neutron monitors and from the GOES spacecraft has made it possible to firmly state that the source of solar rays is solar flares, not shocks generated by such flares. It cannot be ruled out that a similar mechanism, not shocks, is also responsible for the acceleration of cosmic rays in the Galaxy.

Electrostatic Control of Polymorphism in Charged Amphiphile Assemblies.

Stimuli-induced structural transformations of molecular assemblies in aqueous solutions are integral to nanotechnological applications and biological processes. In particular, pH responsive amphiphiles as well as proteins with various degrees of ionization can reconfigure in response to pH variations. Here, we use in situ small and wide-angle X-ray scattering (SAXS/WAXS), transmission electron microscopy (TEM), and Monte Carlo simulations to show how charge regulation via pH induces morphological changes in the assembly of a positively charged peptide amphiphile (PA). Monte Carlo simulations and pH titration measurements reveal that ionic correlations in the PA assemblies shift the ionizable amine pK ∼ 8 from pK ∼ 10 in the lysine headgroup. SAXS and TEM show that with increasing pH, the assembly undergoes spherical micelle to cylindrical nanofiber to planar bilayer transitions. SAXS/WAXS reveal that the bilayer leaflets are interdigitated with the tilted PA lipid tails crystallized on a rectangular lattice. The details of the molecular packing in the membrane result from interplay between steric and van der Waals interactions. We speculate that this packing motif is a general feature of bilayers comprised of amphiphilic lipids with large ionic headgroups. Overall, our studies correlate the molecular charge and the morphology for a pH-responsive PA system and provide insights into the Å-scale molecular packing in such assemblies.

Properties of aqueous solutions containing blends of poly-N-vinylformamide with carboxymethyl cellulose of various degrees of ionization and of composite films of these polymers

Rheological properties of mixtures of dilute and moderately concentrated aqueous solutions of poly-N-vinylformamide and carboxymethyl cellulose of various degrees of ionization were studied. Composite film materials were prepared, and their physicomechanical properties and structural organization were studied.

The Diagnostics of the κ-Distributions from EUV Spectra

The EUV lines suitable to diagnose possible κ-distributions in the solar corona are examined. A set of synthetic spectra for various values of the κ-parameter, characterizing the non-thermal κ-distributions, electron densities, and the mean energy of the distributions are calculated in the spectral range corresponding to the Hinode/EIS and Coronas-F/SPIRIT detectors. The strong EUV lines of Fe in various degrees of ionization are used to analyze the sensitivity of the line ratios to the shape of the distribution function, electron density, and temperature or the parameter T of the κ-distribution. The EUV lines suitable for the diagnostics of the distribution function are proposed and the conditions for their usage are discussed.

Impact of Electron–Electron Collisions on the Spatial Electron Relaxation in Non-Isothermal Plasmas

The impact of electron–electron collisions on the spatial relaxation of electrons in the column-anode plasma of a glow discharge, acted upon by a space-independent electric field and initiated by a constant influx at the cathode side of the plasma, is investigated in inert gas plasmas. The investigations are based on a new method for numerically solving the one-dimensional inhomogeneous Boltzmann equation of the electrons including electron–electron interaction in weakly ionized, collision-dominated plasmas. A detailed analysis of the spatial behaviour of the velocity distribution function and relevant macroscopic properties of the electrons is given for various degrees of ionization and electric field strengths. A significant impact of the electron–electron collisions on the relaxation structure and the resultant relaxation length already at relatively low ionization degrees has been found for low to medium electric fields.

Enthalpy Changes upon Dilution and Ionization of Poly(l-glutamic acid) in Aqueous Solutions

The enthalpy changes accompanying the dilution and ionization of poly(L-glutamic acid) in water have been measured at 25 degrees C for two degrees of polymerization (DP = 115 and DP = 480) at various degrees of ionization, alpha, for a concentration range from about 0.2 to 0.002 monomol/L. The heat of dilution displays an unusual dependence on the degree of ionization, which is in sharp contrast to the behavior of other weak carboxylic polyelectrolytes, such as poly(acrylic acid). The exothermic heat effects observed at low values of alpha become endothermic for the region where the helix-coil transition is most pronounced, and for high degrees of ionization, they are exothermic again. Evidently, an endothermic heat effect, produced by an additional conformational transition in the dilution process, is superimposed on the exothermic enthalpy of dilution, and it overweighs the latter in the region of alpha where the conformational transition is prevailing. The calorimetric titration curve, which gives the dependence of the heat of ionization, deltaH(i), on alpha, has a maximum and is typical for poly(carboxylic acids) which undergo pH-induced conformational transition, such as poly(methacrylic acid). The values of deltaH(i) obtained at two polymer concentrations indicate that the enthalpy of ionization depends on the polypeptide concentration.

Multi-configuration Dirac-Fock andconfiguration-interaction calculations ofAr7+ to Ar17+ ions

Multi-configuration Dirac-Fock and relativistic configuration-interactioncalculations with the inclusion of the Breitinteraction, quantum electrodynamics andfinite nuclear mass corrections have beencarried out in the extended optimal level(EOL) scheme on the energy levels, electricdipole transition rates, oscillatorstrengths and radiative lifetimes ofAr17+ to Ar10+ ions. Thecalculations have been performed in JJ coupling with an empty K shell, openouter shells and varying degrees ofionization in the L shell. The effects of atransverse Breit interaction, finitenuclear mass corrections and quantumelectrodynamics on the energy levels andradiative transition rates are analysed.

Intranetwork phase separation in polyelectrolyte gels

Abstract We have investigated the swelling behavior of polyelectrolyte gels in a low-molecular-weight solvent taking into account the possibility of intragel phase separation. We have shown that, as for the case of a neutral gel considered recently by Moerkerke et al., the coexistence of two phases differing by polymer concentration can also take place inside the polyelectrolyte gel if the amount of solvent is not enough to ensure its free swelling. The phase diagrams for polyelectrolyte gels with various degrees of ionization and with various degrees of stiffness of the gel subchains have been calculated. It has been shown that the region of stability of the two-phase gel increases significantly with increasing number of charges on the network chains and chain rigidity.

Spatial correlations in aqueous protein solutions

The primitive model for ionic solutions combined with the hypernetted chain approximation (HNC) is applied to study spatial correlations in aqueous solutions of ionized globular proteins. The accuracy of the theory is verified by comparison with results of a parallel Monte Carlo simulation. Good agreement of the theoretical results with the interprotein partial structure factors measured in cytochrome c solutions confirms that the model provides a satisfactory description of solute—solute interactions at various degrees of ionization and at different protein and simple electrolyte concentrations. Application of the proposed model in studies of thermodynamic behavior of protein solutions is suggested.

Photoionization of atoms and ions

Calculations of subshell photoionization processes are performed for various atoms (neon, argon, iron and uranium), for various degrees of ionization, within the independent-particle approximation. We discuss the asymptotic behavior and the high-energy features of these cross sections, focusing on subshell cross-section ratio functions. Near threshold, a modified Dirac-Fock theory is used to study core relaxation effects on photoabsorption for argon. Finally we examine the ionic neon total photoabsorption cross section as a function of degree of ionization.

Dielectronic recombination rates for the Fe ions

The empirical rate formula for dielectronic recombination is improved by incorporating existing theoretical data for different ions in various degrees of ionization. The formula is then used to generate a complete set of rate coefficients for the Fe isonuclear sequence. Both the Δ n t≠0 and Δ n t=0 excitation modes are treated separately in the low-density zero-field limit. Explicit data are not available in the regions of N=5–8 and N⩾13, where N is the number of electrons in the ion before capture. A smooth variation of rates in N is predicted for N≳11, but some shell-structure dependence is present around N=2 and N=10.

STRANGE BEHAVIOR BY THE ERUPTIVE SYMBIOTIC STAR V1329 CYGNI

ABSTRACT On six occasions in 1985 and 1986 strong, resolved components of forbidden O III lines were found at velocity displacements of + or - 150 to 200 km/s from the central component whose velocity is similar to that of many lines of various degrees of ionization. A similar component was probably present in 1982. Extensive velocity data are presented and H-alpha profiles at five phases of the 964-day cycle are displayed. The data are discussed in terms of a bipolar flow either in the plane of the orbit or perpendicular to the orbital plane of a symbiotic binary system.

Internal conversion in inner shells of atomic ions and relativistic ionic potentials

Internal conversion coefficients for inner shells of atomic ions of Sn are calculated for various degrees of ionization and compared with neutral atom predictions. The relativistic version of an analytic perturbation theory is used to include screening effects.

Sodium and Chloride Ion Activities in Polyacrylic Acid --- Polyacrylate Solutions at Various Degrees of Ionization.

Sodium and Chloride Ion Activities in Polyacrylic Acid --- Polyacrylate Solutions at Various Degrees of Ionization.

Viscoelastic study of the conformational transition of poly(methacrylic acid) in dilute aqueous solution

AbstractThe dynamic viscosity of dilute aqueous solution of poly(methacrylic acid) (PMA) was measured over the frequency range 2–500 kHz for various degrees of ionization. The relaxation spectrum calculated from the viscosity exhibits a conformational relaxation spectrum in the short‐time region and a rotational one in the long‐time region. The former is fitted by the Zimm theory over the entire range of ionization, including the transition from a compact structure to an open one. The conformational relaxation time begins to increase at the midpoint of the transition region, but the rotational relaxation time increases very markedly in the initial stage of the transition.The present and previously reported experimental findings are interpreted in terms of the assumption that the compact structure is stabilized by short‐range methyl–methyl bonding as well as “long‐range” methyl–methyl bonding (bonding between methyl groups spatially close but remotely connected along the chain contour). In the initial stage of the transition, the latter primarily break up, resulting in expansion of overall chain dimensions, and subsequently the former are destroyed, resulting in the change in local chain conformation.

Heats of dilution of polyacrylic acid at various degrees of ionization

The heats of dilution of polyacrylic acid at four constant degrees of ionization (α = 0, 0.25, 0.50, and 1.00) have been measured in the concentration range 0.6–0.002 monomolal. The heat of dilution for pure acid (α = 0) is positive in the investigated concentration range, whereas it is negative for partially neutralized acid (α = 0.25 and 0.50). For completely neutralized add, for sodium polyacrylate (α = 1), the measured heat effects are exothermic at concentrations above about 0.05 monomolal. while below 0.05 M they become endothermic. The experimental results have been evaluated with the help of a previously developed theoretical treatment based on the cell model.