Equal Valence Research Articles

The Mediating Effect of Place Attachment on the Relationship between Festival Satisfaction and Loyalty to the Festival Hosting Destination

The purpose of this study was to explore the factors that drive festival visitor loyalty to host destinations. Our analysis focused on the role of place attachment as a mediator of the relationship between visitors’ positive evaluation of their festival experience and their loyalty to the host destination. Using structural equation modeling, we found that satisfied visitors at a festival develop a moderate level of emotional attachment to the festival host destination and ultimately become loyal to that destination. Not all dimensions of place attachment and festival satisfaction, however, were statistically significant, nor were they of equal valence in their prediction of the destination loyalty dimensions. Based on these findings, both theoretical and practical implications of this investigation are discussed.

Ion Exchange Kinetics of Heavy Metal Ions on Organic–Inorganic Composite Cation Exchanger Poly-o-toluidine Zr(IV) Tungstate

To study the ion exchange kinetics of heavy metal ions on the organic–inorganic composite cation exchanger poly-o-toluidine Zr(IV) tungstate, Nernst–Planck was computer simulated. Simulated numerical results for counter ions (Cu, Zn, Cd and Pb) of equal valence and four different ionic mobilities are presented to understand the ionic diffusion process. These results are based on the fractional attainment of equilibrium U(τ), of the counter ions under study. The forward (M2+–H+) and reverse (H+–M2+) ion exchange processes are justified as the particle diffusion phenomenon. The self-diffusion coefficient (D o ), energy of activation (E a ), and entropy of activation (∆S*) have also been estimated to understand the ion exchange process occurring over the surface of this cation exchanger and indicated that the ion exchange process is feasible and spontaneous. It is concluded that the difference in activation energies and entropy of activation may facilitate the separation of metal ions. The regeneration capability of this cation exchanger was also explained.

The role of emotions for moral judgments depends on the type of emotion and moral scenario.

Emotions seem to play a critical role in moral judgment. However, the way in which emotions exert their influence on moral judgments is still poorly understood. This study proposes a novel theoretical approach suggesting that emotions influence moral judgments based on their motivational dimension. We tested the effects of two types of induced emotions with equal valence but with different motivational implications (anger and disgust), and four types of moral scenarios (disgust-related, impersonal, personal, and beliefs) on moral judgments. We hypothesized and found that approach motivation associated with anger would make moral judgments more permissible, while disgust, associated with withdrawal motivation, would make them less permissible. Moreover, these effects varied as a function of the type of scenario: the induced emotions only affected moral judgments concerning impersonal and personal scenarios, while we observed no effects for the other scenarios. These findings suggest that emotions can play an important role in moral judgment, but that their specific effects depend upon the type of emotion induced. Furthermore, induced emotion effects were more prevalent for moral decisions in personal and impersonal scenarios, possibly because these require the performance of an action rather than making an abstract judgment. We conclude that the effects of induced emotions on moral judgments can be predicted by taking their motivational dimension into account. This finding has important implications for moral psychology, as it points toward a previously overlooked mechanism linking emotions to moral judgments.

Ab-initio study of the electronic and elastic properties of beryllium chalcogenides BeX (X=S, Se and Te)

Ab-initio methods have been employed to investigate the electronic and elastic properties of beryllium chalcogenides (namely BeS, BeSe and BeTe). The electron momentum density, autocorrelation function and energy band gap have been computed using the linear combination of atomic orbitals method. Using the full potential linearized augmented plane-wave and projector-augmented wave methods, the energy bands and density of states (DOS) along with elastic properties are also calculated. The electronic band structure, total and partial DOS and elastic moduli obtained from the present calculations are found to be in good agreement with available earlier data. The calculated valence band width, equal valence electron density curve and bulk modulus confirm the trend of ionicity BeS>BeSe>BeTe.

Comparison of Impedance Spectroscopy Expressions and Responses of Alternate Anomalous Poisson−Nernst−Planck Diffusion Equations for Finite-Length Situations

Two empirical, but plausible, previously published independent generalizations of the standard Poisson−Nernst−Planck (PNP) continuum diffusion model for mobile-charge conduction in liquids and solids are discussed, their responses are compared, and their physical appropriateness and usefulness for data fitting are investigated. They both involve anomalous diffusion of PNPA type with power-law frequency-response elements involving fractional exponents. Both models apply to finite-length regions of material between completely blocking electrodes and, for simplicity, deal primarily with positive and negative charge carriers of equal valence numbers and mobilities. The charge carriers may be either ionic or electronic. The first PNPA model, model A, involves the common separation of the expression for ordinary PNP impedance into an interface diffusion part and a high-frequency limiting conductance and capacitance, followed by the replacement of all normal diffusion elements in the former by anomalous ones. It...

Transient Ion-Pair Dynamics Induced by External Electric Field in Electrolytic Cell with Blocking Electrodes

The conventional equations describing the transport of free ions in electrolytes have been extended to take into account the behavior of the ion pairs. The space and time dependencies of the ion-pair density and ion-pair fluxes in the electrolytic cell with blocking electrodes, when disturbed by a stepwise, external electric field, have been examined by numerical calculations. Solutions are obtained for different regimes: weak and strong electric fields, symmetrical electrolytes (equal ion valence and electrically neutral ion pairs), unsymmetrical electrolytes (different ion valence and charged ion pairs), different diffusivity (mobility) of the free ions, etc. The nonlinear, competitive processes defining the time evolution of the ion pairs have been analyzed and discussed. For symmetrical electrolytes, the ion-pair densities have a minimum at the middle of the cell and maxima at the two electrodes, whereas the neutral ion-pair flux is dominated by diffusion processes. For unsymmetrical electrolytes, the ion-pair density has a maximum at the electrode with higher polarization, whereas the charged ion-pair flux is dominated by migration. The ion-pair fluxes in a strong electric field tend to reverse direction in space and time. The oscillations occur in a short time interval, slightly delayed from the initial moment when the electric field is switched on.

A study of electronic structure of CdSe by Compton scattering technique

The electronic structure of CdSe through a Compton profile study is presented in this paper. Theoretical calculations are performed following the empirical pseudopotential method and the linear combination of atomic orbitals method. The measurement on a polycrystalline sample of CdSe is performed using 59.54 keV gamma-rays from 241Am radioisotope. The spherically averaged theoretical Compton profiles are in agreement with the measurement. The best agreement is, however, shown by the linear combination of atomic orbitals method based on the Hartree–Fock theory. The electron momentum density is also discussed in terms of theoretical anisotropies in the directional Compton profiles calculated from the linear combination of atomic orbitals method. On the basis of equal valence electron-density profiles, it is found that CdSe is less covalent compared to ZnSe. The superposition model suggests the transfer of 1.6 electrons from Cd to Se on compound formation.

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: A partially perturbative density functional theory study

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Cation specific binding with protein surface charges

Biological organization depends on a sensitive balance of noncovalent interactions, in particular also those involving interactions between ions. Ion-pairing is qualitatively described by the law of "matching water affinities." This law predicts that cations and anions (with equal valence) form stable contact ion pairs if their sizes match. We show that this simple physical model fails to describe the interaction of cations with (molecular) anions of weak carboxylic acids, which are present on the surfaces of many intra- and extracellular proteins. We performed molecular simulations with quantitatively accurate models and observed that the order K(+) < Na(+) < Li(+) of increasing binding affinity with carboxylate ions is caused by a stronger preference for forming weak solvent-shared ion pairs. The relative insignificance of contact pair interactions with protein surfaces indicates that thermodynamic stability and interactions between proteins in alkali salt solutions is governed by interactions mediated through hydration water molecules.

Both Happy and Sad Melodies Modulate Tonic Human Heat Pain

The mechanism of music effects on pain perception remains to be elucidated. To determine which component (mood or valence) of music is more important in music-induced hypoalgesia, we compared the effects of 2 melodies with different moods (happy vs sad) but with the same degree of valence (pleasant vs unpleasant) to an affective neutral lecture and a control (baseline) on the objective and subjective responses to tonic heat pain. Our hypothesis was that if mood was the key component, the happy melody would reduce pain, whereas the sad one would exacerbate pain; and if valence is the key component, the 2 melodies would both alleviate pain. Twenty females participated in this study which consisted of 4 conditions (baseline, happy melody, sad melody, and lecture). Pain tolerance time (PTT), pain intensity, and distress dynamics and the characteristics of pain were measured. A newly devised multiple affective rating scale (MARS) was employed to assess the subjective experience of auditory perception. Both happy and sad melodies of equal valence resulted in significant lower pain ratings during the pain test and were in contrast to the mood prediction. These results indicate that the valence of music, rather than the mood it induced, appears to be the most likely mediator of the hypoalgesic effect of the different music. This article provides new evidence that the valence of music is more crucial than mood in affective pain modulation. This finding gives impetus for health professionals to manage pain more effectively in patients with proper music.

Atomvolumen, Packungsdichte der Atome und chemische Bindung in nichtmetallischen Elementen

The atomic volume of crystalline elements is largely determined by the packing density of atoms in the respective modification. The determination of packing density is improved by assuming that the atomic distances depend on bond valences according to Pauling's equation. With the additional assumption of equal valence in different modifications, the experimental atomic volume of an element in any given structure is reduced to its volume in close-packed structures, e.g. f.c.c. The ratio of this reduced atomic volume and the experimental atomic volume is a measure of packing density. Reduced atomic volumes of C, Si, Ge, P, As, S and Se, as calculated from different modifications, correspond in most cases to within less than +/-1% for each element, even if calculated from extremely different structures like diamond and buckminsterfullerene in the case of carbon, or from numerous modifications of sulfur with annular molecules of different sizes. Exceptions (graphite, white phosphorus, tin and selenium) indicate deviating valences.

Magnetoelastic mechanism of magnetoelectric interaction

The magnetoelastic mechanism of the magnetoelectric interaction characterized by the energy ϕmu is analyzed theoretically. This interaction is described in terms of the expansion of the magnetic energy ϕm in powers of components of the vectors uj (displacements of crystal lattice sites from equilibrium positions) rather than the vectors ∇u, which determine the magnetostriction component ϕms of the magnetoelastic energy. One more difference between the energies ϕmu and ϕms lies in the fact that the magnetoelectric energy ϕmu corresponds to the interaction of magnetic excitations with optical phonons, whereas the magnetostriction energy ϕms corresponds to the interaction of magnetic excitations only with acoustic phonons. It is established that the magnetoelectric interaction is affected by the electroactive optical phonons (interacting with the electric field), which, as a rule, make a small contribution to the total number of optical branches of the phonon spectrum. The magnetoelectric energy ϕmu is described within the approach in which all nonelectroactive branches of optical phonons are automatically excluded from consideration. This approach is based on the concept of the electric sublattice formed by all chemically identical ions with equal valences. Analysis is performed using the Fe2TeO6 compound as an example.

The Influence of Charge Density of Chitosan in the Compaction of the Polyanions DNA and Xanthan

In this study the relative importance of valence and charge density of the polycation chitosan on the compaction process of DNA and xanthan is investigated. Chitosans with approximately equal valence but differing in their charge density were employed to form polyelectrolyte complexes with the two polyanions. The resulting structures (toroids, rods, and globules) have been visualized by AFM. For DNA-chitosan the complexation process was additionally studied by utilizing the fluorescent probe ethidium bromide. The results show that not only the total charge per chitosan molecule (valence), but also the charge density is important in determining the association with polyanions such as DNA and xanthan. Furthermore, it is demonstrated that the pH at which the complexation takes place is an important parameter in the complexation process, influencing the structures formed.

Comparison of ion sites and diffusion paths in glasses obtained by molecular dynamics simulations and bond valence analysis

Based on molecular dynamics simulations of a lithium metasilicate glass we study the potential of bond valence sum calculations to identify sites and diffusion pathways of mobile Li ions in a glassy silicate network. We find that the bond valence method is not well suitable to locate the sites, but allows one to estimate the number of sites. Spatial regions of the glass determined as accessible for the Li ions by the bond valence method can capture up to 90% of the diffusion path. These regions however entail a significant fraction that does not belong to the diffusion path. Because of this low specificity, care must be taken to determine the diffusive motion of particles in amorphous systems based on the bond valence method. The best identification of the diffusion path is achieved by using a modified valence mismatch in the BV analysis that takes into account that a Li ion favors equal partial valences to the neighboring oxygen ions. Using this modified valence mismatch it is possible to replace hard geometric constraints formerly applied in the BV method. Further investigations are necessary to better understand the relation between the complex structure of the host network and the ionic diffusion paths.

Strong Resistance of a Thin Crystalline Layer of Balanced Charged Groups to Protein Adsorption

Resistance of mixed self-assembled monolayers (SAMs) with various counter-charged terminal groups of different valence and protonation/deprotonation states to nonspecific protein adsorption is investigated. It is demonstrated that excellent nonfouling surfaces can be readily constructed from mixed positively and negatively charged components of equal valence in a wide range of thiol solution compositions. Furthermore, the lattice structure of one of the mixed SAM systems studied is revealed by atomic force microscopy (AFM) to be (5.2 +/- 0.2 A x 5.2 +/- 0.2 A)60 degrees . Results indicate that the packing structure of mixed charged SAMs is determined by strong charge-charge interactions of the terminal groups rather than S-Au and chain-chain interactions. This work provides direct evidence that conformational flexibility is not required for protein resistance of a surface and even a single compact layer of charged groups of balanced charge with a crystalline structure can resist nonspecific protein adsorption, suggesting that tightly bound water molecules on the topmost part of the mixed SAMs play a dominant role in surface resistance to nonspecific protein adsorption.

Specific Interactions versus Counterion Condensation. 2. Theoretical Treatment within the Counterion Condensation Theory

Polyuronates such as pectate and alginate are very well-known examples of biological polyelectrolytes undergoing, upon addition of divalent cations, an interchain association that acts as the junction of an eventually formed stable hydrogel. In the present paper, a thermodynamic model based on the counterion condensation theory has been developed to account for this cation-induced chain pairing of negatively charged polyelectrolytes. The strong interactions between cross-linking ions and uronate moieties in the specific binding site have been described in terms of chemical bonding, with complete charge annihilation between the two species. The chain-pairing process is depicted as progressively increasing with the concentration of cross-linking counterions and is thermodynamically defined by the fraction of each species. On these bases, the total Gibbs energy of the system has been expressed as the sum of the contributions of the Gibbs energy of the (single) chain stretches and of the (associated) dimers, weighted by their respective fractions 1 - theta and theta. In addition, the model assumes that the condensed divalent counterions exhibit an affinity free-energy for the chain, G(C)(aff,0), and the junction, G(D)(aff,0), respectively. Moreover, a specific Gibbs energy of chemical bonding, G(bond,0), has been introduced as the driving force for the formation of dimers. The model provides the mathematical formalism for calculating the fraction, theta, of chain dimers formed and the amount of ions condensed and bound onto the polyelectrolyte when two different types of counterions (of equal or different valence) are present. The effect of the parameter G(bond,0) has been investigated and, in particular, its difference from G(C,D)(aff,0) was found to be crucial in determining the distribution of the ions into territorial condensation and chemical bonding, respectively. Finally, the effect of the variation of the molar ratio between cross-linking ions and uronic groups in the specific binding sites, sigma0, was evaluated. In particular, a remarkable decrease in the amount of condensed counterions has been pointed out in the case of sigma0 = 1/3, with respect to the value of sigma0 = 1/4, characterizing the traditional "egg-box" structure, as a result of the drop of the charge density of the polyelectrolyte induced by complete charge annihilation.

Hydration Energy Determines Isovalent Cation Exchange Selectivity by Clay Minerals

Cation exchange is one of the most venerable concepts in soil science, yet it needs rethinking. This paper presents an extremely simple conceptual framework for interpreting many observed trends in cation exchange. Taking the example of Cs‐K exchange, the methods of computational molecular mechanics found that Cs‐montmorillonite is considerably higher in energy than K‐montmorillonite at constant water content, in agreement with inferences from a new thermodynamic cycle representation of cation exchange. Since montmorillonite selects Cs+ over K+ in real experiments, these results mean that alkali cation‐exchange selectivity is controlled by selectivity of the solution phase for the more strongly hydrated cation. Thus the clay does not “select” for Cs+ over K+ in any positive sense and it may be more useful to consider cation exchange as a partitioning reaction: Given two cations of equal valence, the more weakly hydrated will tend to partition into the “subaqueous” smectite interlayer phase. This concept seems not only parsimonious, but also more accurate than other hypotheses for cation exchange selectivity that impute more favorable interactions between smectite surfaces and the selected cations; such theories err by ignoring energy changes in the solution phase. This simple partitioning concept rationally explains the alkali and alkaline earth selectivity sequences as well as the selectivities of smectites for organic cations over inorganic, for larger organic cations over smaller, and for organometallic complexes over the uncomplexed metal.

Bond valence and finite graph symmetries

Abstract The graph theory prediction of bond valence distributions in a crystal network is reformulated in a form more familiar to chemists, that of symmetry-adapted functions. The graph theory terms relevant to this exposition are explained, including graph matrices, graph vector spaces and graph automorphism groups. It was found that the vertex and edge sets of a chemical graph form representations of the graph automorphism group. These representations may be expressed as a sum of irreducible representations using the group character table in the usual way. Alternatively the classes of the individual orbits spanned may be used to derive these irreducible representations. The orthogonal cut and cycle subspaces of the edge space can be defined so as to also transform as a sum of irreducible representations. Hence appropriate symmetry-adapted orthogonal basis vectors may be chosen for the vertex and edge spaces. Removing the usual Equal Valence Rule constraint creates a solution space, a range of possible solutions for a particular prob lem. This solution space may be found by combining a set of contributions from the cut space vectors fixed by the atom valences, with a convex polytope in the cycle space which is defined by the non-negativity of the individual bond valences. The complete procedure is illustrated for the β-Ga2O3 structure.

Selection rules in (e, 2e) spectroscopy from ferromagnetic surfaces

Electron pair emission from ferromagnetic crystalline surfaces, which occurs due to thecollision of an incident low-energy electron with a valence electron, is shown to be governedby spatial and spin selection rules. Valence electron states with spatial parts antisymmetricwith respect to the reaction plane are not observable for any spin configuration. If there isa spatial symmetry plane normal to the reaction plane, spin-polarized primary electronsselectively probe equal and opposite spin valence electrons. These analytical findings arefurther elaborated for ferromagnetic cubic (110) surfaces and illustrated by numericalresults for Fe(110).

Electron–hole symmetry and spin–orbit splitting in IV–VI asymmetric quantum wells

It is shown that, due to the electron–hole symmetry of the fundamental gap of the lead–salts (PbTe, PbSe and PbS), the Rashba spin splitting in their flat band asymmetric quantum wells is much reduced with the usual equal conduction and valence band-offsets. Different from the III–V case, we find that the important structure inversion asymmetry for the Rashba splitting in IV–VI quantum wells with different left and right barriers is not a material property (i.e., barrier height, effective mass or band gap) but results from the band alignment. This is shown by specific envelope function calculations of the spin-dependent subband structure of Pb 1− x Eu x Te/PbTe/Pb 1− y Eu y Te asymmetric quantum wells ( x≠ y), based on a simple but accurate four-band kp model for the bulk band structure near the gap, which takes into account band anisotropy, nonparabolicity and multi-valley effects.