Meyer Equation Research Articles

Indentation size effect in Knoop and Vickers hardness measurement of dental resin-based composites

ObjectivesComparisons of material hardness may be affected by the indentation size effect (ISE), which is characterized by increasing hardness values at decreasing loads. This study aimed to assess the influence of load, dwell time and measurement method on ISE in dental resin-based composites with different filler content. MethodsKnoop (HK) and Vickers (HV) microindentation hardness of Filtek Ultimate Universal Restorative (FU) and Filtek Supreme Flowable Restorative (FF) was measured under different loads (0.098–2.96 N, i.e. 10-300 gf) and dwell times (5–30 s). Their effects on HK and HV were evaluated using repeated measures ANOVA, which was also used to compare the measurement methods. Coefficients of Meyer's equation, proportional specimen resistance (PSR) model and a modified PSR model were calculated using regression analyses. ResultsISE was more pronounced for the highly-filled FU than for the less-filled FF, and HK was more susceptible to ISE than HV. The effect of dwell time was similar for both materials and measurement methods; hardness values decreased with dwell time, significantly between 5 s and 30 s. SignificanceThe possible presence of ISE should be considered when determining measurement conditions for the microindentation hardness of dental resin-based composites. HV was found to be less sensitive to ISE and provided stable hardness values at lower loads than HK. Due to the high variability of composites, any hardness measurement should be preceded by mapping the effect of load to ensure that load-independent hardness is measured. If hardness values continue to decrease in the whole range of increasing loads, load-independent hardness can be calculated using the PSR model.

Insights into the volumetric properties, conductive property, and interaction behaviors of two nitrile functionalized ionic liquids mixture systems with γ-butyrolactone

Two functionalized ionic liquids, 1-cyanopropyl-3-methylimidazolium bistrifluoromethanesulfonimide ([C3CNmim][TFSI]) and 1-cyanopropyl-3-methylimidazolium trifluoromethanesulfonate ([C3CNmim][OTF]) were blended with γ-butyrolactone (GBL) under the full concentration range (molar fraction from 0 to 1) to form mixture systems, respectively. The densities and conductivities of pure ILs and their mixture systems were measured in the temperature range 288.15–343.15 K under normal pressure. The Vogel–Fulcher–Tammann (VFT) equation is employed to investigate the temperature dependence of conductivity. The volumetric properties of the mixture systems, excess molar volumes (VE) and apparent molar volumes (Vϕ), were calculated from the density data. The Redlich–Kister (R–K) polynomial equation and Redlich–Rosenfeld–Meyer (RRM) equation were used for the fittings of the VE and Vϕ, respectively. Further, the behaviors of intermolecular interactions in the mixture systems were explained by a combined analysis method composing of the assessment of the volumetric properties changes, the differential scanning calorimetry (DSC) analysis, the infrared (IR) spectrum shifts, and COSMO-RS methodology based on density functional theory (DFT) calculations. The stable optimized structures, H-bonding information, interaction energies, and charge distributions were consequently obtained. It can be found that the addition of the GBL weakened the hydrogen bonding interactions between the IL cations and anions. The [C3CNmim][TFSI] + GBL mixture system shows the lowest energy difference and it may give strong ion-solvent interactions when compare to [C3CNmim][OTF] mixture system.

Dimensional effect when measuring Martens hardness

One of the most common methods of non-destructive testing, hardness testing, is used to evaluate the properties of materials. This is due to the ease of measurement and testing of the finished part, which will be used in the future, high productivity of the method, the ability to assess other mechanical properties of the material: elasticity, creep, tensile strength. An important aspect in the study of the hardness using in the range the Berkovich and Vickers indenters, which are more consistent with non-destructive testing, while the methods of Brinell and Rockwell leave quite large deformations, in our opinion, which further promote the development of structural defects and reduce the service life, which are not acceptable in critical products. Due to the improvement of product manufacturability, more and more manufacturers are trying to minimize the size of the part, while increasing their performance by applying a reinforced layer, which, in turn, should seek to reduce the thickness with increased service life. It is also impossible to study the hardness of very small products in the micro range due to the large mismatch between the dimensions of the product under test and the test method. In our opinion, the study of hardness by the Berkovich method in comparison with the Vickers method is more expedient for use with the same physicochemical properties of the material because of a larger scatter of hardness values between the compared methods, although they should be almost the same, with a small difference. An important omission to a certain year was the dimensional effect. Goal. The aim of the study is to assess the nature of the change in hardness with increasing load on the indenter, using the functional dependence of the hardness on the depth of the indenter. For this purpose, it is necessary to establish such connection for an indenter of various geometry. In this regard, we consider it appropriate to check the validity of the Meyer equation, which relates the load to the size of the imprint, for different indenters and materials. Results. When the hardness is calculated according to the Martens scales, the Vickers and Berkovich indenters are applied to the function of the surface area of the working part of the tip. An important factor of the consistency of the results in the increase in hardness is the small effect. The reasons for this can be very negligible. The sizeable effect is significantly infused into the results of increasing hardness, changing from 2,5 to 3,0 folds.

Densities and Apparent Molar Volumes of Aqueous Solutions of NaClO4, KClO4, and KCl at Temperatures from 293 to 343 K

Densities of aqueous solutions of the strong electrolytes sodium perchlorate, potassium perchlorate, and potassium chloride have been measured by vibrating-tube densimetry at 5 K intervals over the temperature range 293.15 ≤ T (K) ≤ 343.15 up to near-saturation concentrations (for NaClO4 and KClO4) or to about 2 mol·kg–1 (for KCl) at 0.1 MPa pressure. Particular attention was paid to solute purity and solution composition. The densities were used to calculate the corresponding apparent molar volumes, Vϕ, which considerably extend and improve the quality of the volumetric database for these salts, especially with respect to temperature. Where comparisons were possible, the present Vϕ results agreed well with most literature data, with the significant exception of NaClO4(aq) at higher temperatures. The Vϕ values were extrapolated to infinite dilution using an extended Redlich–Rosenfeld–Meyer equation to yield the standard state partial molar volumes (V2o). A combination of these values with relevant literature data and a well-established extra-thermodynamic assumption was used to estimate the standard molar volumes, V2o(ion), of several key monovalent ions as functions of temperature. These values appear to be more reliable than existing estimates based on older data, and will be useful for determining volumes of other ions in aqueous solution.

Apparent molar volumes and relative viscosity of [C3C1PYR][Br]/[C2OHC1PYR][Br] + H2O

The binary mixtures of 1-propyl-1-methylpyrrolidinium bromide ([C3C1PYR][Br]) salt and 1-hydroxyethyl-1-methylpyrrolidinium bromide ([C2OHC1PYR][Br]) salt with secondary distilled water were prepared at low concentrations. The density and viscosity of the studied binary mixtures have been determined. The values of the studied properties were recorded every 5 K at temperature range 288.15–318.15 K. The values of apparent molar volume (Vϕ, m3 mol−1) and relative viscosity (ηr) were calculated according to the experimental values of density and viscosity of the systems. The side chains effects in each salt cation are discussed on the above properties. The limiting parameters (Vϕ0, m3 mol−1) were obtained and analyzed by fitting the apparent molar volumes with concentration by a Redlich–Rosenfeld–Meyer equation. The relative viscosities (ηr) were also calculated and analyzed according to the traditional equation of Jones–Dole at different concentration ranges.

Indentation size effect of germanium single crystal with different crystal orientations

In order to study the indentation size effect (ISE) of germanium single crystals, nano-indentation experiments were carried out on the (100), (110) and (111) plane-orientated germanium single crystals. The true hardness of each crystal plane of germanium single crystals was calculated based on the Meyer equation, proportional sample resistance (PSR) model and Nix—Gao model, and the indentation size effect (ISE) factor of each crystal plane was calculated. Results show that, the germanium single crystals experience elastic deformation, plastic deformation and brittle fracture during the loading process, and the three crystal planes all show obvious ISE phenomenon. All three models can effectively describe the ISE of germanium single crystals, and the calculated value of Nix—Gao model is the most accurate. Compared with the other two crystal planes, Ge (110) has the highest size effect factor m and the highest hardness, which indicates that Ge (110) has the worst plasticity.

Change in the Mechanical Properties of Commercial-Purity Copper during Alternating Elastoplastic Deformation

The mechanical properties of commercial-purity copper strips subjected to alternating elastoplastic deformation in a mangle have been studied. One pass is shown to be sufficient to increase the yield strength of a treated strip by four times with only a slight change in the ultimate strength and a relatively insignificant decrease in the ductility. The study of the correlation of the hardness with the strength characteristics shows that Vickers microhardness HV0.1 of the treated strip surface increases to a lesser degree than the yield strength does. In this case, the yield-strength Brinell hardness that corresponds to a residual strain of 0.2% increases by almost four times. The strain-hardening coefficients that enter in the Meyer equation for indentation and the Ludwik–Hollomon equation for tension have been determined. Their correlation is observed for the copper strips before and after treatment.

Study on solute-solvent interactions in the aqueous solutions containing guaifenesin drug, sodium chloride and potassium chloride salts in viewpoint of volumetric, electrical conductivity properties and quantum computing

Sodium and potassium ions have an important role in controlling the blood pressure in the body. Potassium ion along with sodium ion regulates the water and the acid-base balances in the tissues and blood. In this work, solute-solvent interactions in the aqueous solutions containing the guaifenesin drug (GG), NaCl and KCl salts were studied. To reach this purpose, the density and electrical conductivity data for GG drug in water and aqueous solutions of NaCl and KCl were measured within salt and drug molality range of (0.05, 0.1, and 0.15) mol kg−1 at T = (298.15, 308.15 and 318.15) K. The apparent molar volumes (Vφ) were calculated from density data. These data were analysed with Redlich–Meyer equation to find the limiting apparent molar volume. The low concentration Chemical Model (lcCM) was used for evaluating the limiting values of the molar conductivity (Λ0), the association constant (Ka) and the standard Gibbs energy for the ion-association process. We also optimized the structures and calculated the Gibbs energies of considered molecules in gas phase with Gaussian 03 W using the Hartree-Fock approximation with 6-311G basis set. Tomasi’s polarized continuum model (PCM) with basis set of 6-311G was used for optimizing and calculating the Gibbs energies of molecules in aqueous phase. The calculated solvation Gibbs energies were used for elucidating the solute-solvent interactions.

Equivalent strain hardening exponent of anisotropic materials based on spherical indentation response

Abstract Uniaxial strain hardening exponent is not suitable for describing the strain hardening behaviors of the anisotropic materials, especially when material deforms in the multi-axial stress states. In this work, a novel method was proposed to estimate the equivalent strain hardening exponent of anisotropic materials based on an equivalent energy method. By performing extensive finite element (FE) simulations of the spherical indentation on anisotropic materials, dimensionless function was proposed to correlate the strain hardening exponent of anisotropic materials with the indentation imprint parameters. And then, a mathematic expression on the strain hardening exponent of anisotropic materials with the indentation imprint was established to estimate the equivalent strain hardening exponent of anisotropic materials by directly solving this dimensionless function. Additionally, Meyer equation was modified to determine the yield stress of anisotropic materials. The effectiveness and reliability of the new method were verified by the numerical examples and by its application on the TC1M engineering material.

Densities and Apparent Molar Volumes of Aqueous Solutions of K4Fe(CN)6, K3Fe(CN)6, K3Co(CN)6, K2Ni(CN)4, and KAg(CN)2 at 293 to 343 K

Densities of aqueous solutions of K4Fe(CN)6, K3Fe(CN)6, K3Co(CN)6, K2Ni(CN)4, and KAg(CN)2 have been measured with a vibrating-tube densimeter at temperatures from 293.15 to 343.15 at 5 K intervals over the approximate concentration range 0.02 to 0.4 mol·kg–1. Apparent molar volumes, Vϕ, calculated from these data were fitted with an extended form of the Redlich–Rosenfeld–Meyer equation to obtain the standard partial molar quantities, V°. The Vϕ and V° values for all the salts are in reasonable agreement with literature data at all temperatures. Deviations of the Vϕ values from the Debye–Huckel limiting law were found to increase considerably with increasing anion charge. Values of V° for the cyanometallate anions were obtained using an appropriate extrathermodynamic assumption and were found to increase with increasing crystallographic size or ionic charge except for Fe(CN)64–, which shows a remarkable contraction of more than 35 cm3·mol–1 relative to Fe(CN)63–. The origins of this anomaly are unclear. Isobaric expansivities, α, of all the salt solutions show the greatest increase with solute concentration, but the smallest dependence on the nature of the anion, at lower temperatures. These effects are consistent with the dissolved ions changing from water-structure breaking to net structure making with increasing temperature.

Effect of fruit and milk sugars on solute–solvent interactions of diphenhydramine-hydrochloride drug in aqueous solutions in viewpoint of volumetric and transport properties

Abstract The effect of (D−)-fructose (fruit sugar), (D+)-galactose and (D+)-lactose (milk sugar) on the solute–solvent interactions occurred between the diphenhydramine-hydrochloride (DPH-HCl) drug and water was studied. To this end, the density, speed of sound and viscosity data for DPH-HCl drug in water and aqueous solutions of (D−)-fructose, (D+)-galactose and (D+)-lactose should have been measured. Thermodynamic properties such as the apparent molar volume (Vϕ) and apparent molar isentropic compression (Ks,m) were calculated from the density and speed of sound values within sugar molality range of (0.05, 0.1, and 0.15) mol kg−1 at T = (288.15, 293.15, 298.15, 308.15 and 318.15) K. Extrapolation to the infinite dilution of Vϕ and Ks,m values with using Redlich–Meyer equation was applied to find the corresponding limiting apparent molar quantities. Jones–Dole equation was used to obtain the viscosity B-coefficients. Interparticle interactions occurred between the DPH-HCl drug and water were determined by calculating the transfer parameters of limiting apparent molar volume and viscosity B-coefficient from DPH-HCl in water to the DPH-HCl in aqueous (D−)-fructose, (D+)-galactose and (D+)-lactose solutions.

Interrelation between Strains and Parameters of Metal Strengthening upon Tension and Indentation in Plastic Region

This article discusses analytical dependences of uniform elongation δp and ratios of yield strength to ultimate strength of metal on parameter of strain strengthening n in the Meyer equation. These dependences are verified experimentally for carbon and pearlitic steels upon determination of n using oblique illumination in a microscope for measurement of indentation diameter. The Meyer equation cannot be applied for some austenite steels because of structural phase transformations in deformed metal under indentation.

Densities and Molar Volumes of Aqueous Solutions of Li2SO4 at Temperatures from 343 to 573 K

Densities of aqueous solutions of lithium sulfate (Li2SO4) at solute molalities ranging from 0.05 to 2.7 mol·kg–1 have been measured by vibrating-tube densimetry over the temperature range 373.15 ≤ T/K ≤ 573.15 at pressures close to the saturated vapor pressure of pure water. The apparent molar volumes (Vϕ) of Li2SO4(aq) calculated from these data together with previously published data at 323.15 and 343.15 K were fitted using a modified Redlich–Rosenfeld–Meyer equation, which in turn was used to extrapolate the experimental data to infinite dilution to obtain the standard partial molar volumes. A comparison of the present and literature data revealed the latter are inaccurate at low concentrations and are increasingly unreliable at higher temperatures. The combination of the present results with selected literature data produced a reliable equation of state for Li2SO4(aq) covering the temperature and pressure ranges 323.15 ≤ T/K ≤ 573.15 and 0.1 ≤ p/MPa ≤ 40. The volumetric behavior of Li2SO4(aq) was fou...

Densities and Apparent Molar Volumes of Aqueous Solutions of Li2SO4 and LiCF3SO3 at Temperatures from 293 to 343 K

Densities of aqueous solutions of lithium sulfate (Li2SO4) and lithium trifluoromethanesulfonate (LiCF3SO3) at solute molalities ranging from 0.05 to 2.7 or 9.6 mol·kg–1, respectively, have been measured by vibrating-tube densimetry over the temperature range 293.15 ≤ T/K ≤ 343.15 at 0.1 MPa pressure. The apparent molar volumes (Vϕ) of Li2SO4(aq) and LiCF3SO3(aq) derived from these data were fitted using an extended Redlich–Rosenfeld–Meyer equation. The Vϕ values for the two systems exhibit quite different dependences on concentration and temperature, as do the isobaric expansibilities. A combination of the present and literature data reveals that the densities for Li2SO4(aq) given in standard compilations are unreliable at low concentrations. Comparison of the present results with literature data for related salts shows that Vϕ(LinX) and Vϕ(NanX) exhibit a crossover at ≈0.5 mol·kg–1 for both systems, similar to those observed previously for other lithium and sodium salts. Consideration of an appropriate ...

Parameterization and optimization of hypersonic-gliding vehicle configurations during conceptual design

Three-dimensional class/shape function transformation (CST) approach is an analytical method, and it can define the geometrical shapes by a small number of parameters and it is refined to enhance the parametric ability in this study. The interface between the upper and lower surfaces is considered by introducing additional parametric items, and it will be no longer a flat plane. The inviscid engineering methods based on modified Newton theory and Prandtl–Meyer equation are employed to estimate the Hypersonic gliding vehicle's aerodynamic properties. The accuracies of these methods are also validated. In order to obtain vehicles with high lift-to-drag ratio as well as large volumetric efficiency, multi-objective optimization algorithm, NSGA-II, has been utilized. The obtained result shows that the Pareto front of the multi-objective problem based on the refined three-dimensional CST method is in front of the Pareto front based on the original three-dimensional CST method, and this implies that the refined method can find configurations with better performance than the original one. One of the configurations on the Pareto front has been analyzed, and its aerodynamic performance has been studied by both panel method and the CFD method. The results show that the obtained configuration owns outstanding aerodynamic properties.

Study of Apparent Molar Volumes for Ionic Liquid, 1-Ethyl-3-methyl Imidazolium Chloride in Aqueous Lithium Nitrate, Lithium Bromide, and Lithium Chloride Solutions at Temperatures (298.15 to 318.15) K

The densities of ternary systems ([Emim][Cl]+ LiCl + H2O), ([Emim][Cl] + LiBr + H2O), and ([Emim][Cl]+ LiNO3 + H2O) and also binary system ([Emim][Cl] + H2O) were measured at T = (298.15 to 318.15) K using a vibrating U-tube densimeter. On the basis of experimental density data, the apparent molar volumes, Vφ, were computed. The values of apparent molar volumes for binary system were correlated to Redlich–Meyer and Pitzer equations and for ternary systems were correlated to Redlich–Meyer equation and apparent molar volumes at infinite dilution, Vφ0, are also calculated. Our results showed a negative transfer volume of [EmimCl] from water to the aqueous LiCl, LiBr, and LiNO3 solutions, which decrease by enhancing the salt mass fraction. The solute–solvent interactions and structure making or breaking ability of [Emim][Cl] have been discussed in details. The results of second derivative of limiting apparent molar volumes showed that the studied ionic liquid in this work acts as a structure maker.

The study of solute–solvent interactions in 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate + acetonitrile from solvent activity, density, speed of sound, viscosity, electrical conductivity and refractive index measurements

The solute–solvent interactions that occurred between the ionic liquid of 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate and acetonitrile have been studied. For this purpose, the vapor–liquid equilibrium data (solvent activity, osmotic coefficient and vapor pressure) were determined for 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate in acetonitrile by the isopiestic method at 298.15K. Experimental osmotic coefficients are reliably correlated by Pitzer and Archer extension of Pitzer models. These models were also used to calculate the vapor pressure values. Density, speed of sound, viscosity, electrical conductivity and refractive index values were also measured for this binary system at T=288.15, 293.15 and 298.15K. Density and speed of sound values have been used to calculate the apparent molar volumes and apparent molar isentropic compression. The corresponding limiting apparent molar quantities were found by extrapolation to infinite dilution with using Redlich–Meyer equation. Viscosity B-coefficients were obtained from Jones–Dole equation. Low concentration Chemical Model (lcCM) of conductance equation in terms of ion association constant and limiting molar conductivity was used to analyze the electrical conductivity data. The standard Gibbs energy for the ion-association process was also calculated. Lorentz–Lorenz equation was used to calculate the values of molar refraction.

Effects of bombardment of negative oxygen ions on amorphous indium gallium zinc oxide thin films by superimposed rf/dc magnetron sputtering

During the sputtering process, the bombardment effect of negative oxygen ions (NOIs) on the thin-film properties of amorphous indium gallium zinc oxide (a-IGZO) was investigated. The energies of NOIs determined by in situ ion energy analyses are in good agreement with the values obtained using the Meyer equation. Furthermore, we find that the energies of NOIs are sufficiently high to affect the lattice distortion and/or displacement in a-IGZO films. The overall analysis revealed that the bombardment of NOIs has a considerable effect on a-IGZO film properties. Our work demonstrates that the bombardment of NOIs is a crucial issue for achieving high-quality a-IGZO films.

Conceptual Study on Control-Integrated Design Based on Multidisciplinary Tradeoff Needs for Morphing Waveriders

AbstractThe waverider configuration is a type of aerodynamic shape providing a high lift-to-drag ratio and reasonable flight capacity for hypersonic vehicles. However, hypersonic waveriders are marred by serious design problems wherein the flight performance continually deteriorates if there are deviations in the expected flight conditions. As a result, a combination of hypersonic vehicle design with intelligent morphing technologies may be advantageous in addressing flight stability issues experienced during large flight envelopes. This paper discusses the concepts of nonlinear dynamics and integrated design methods with regard to morphing waveriders. First, a parameterized longitudinal model of a hypersonic vehicle is established in terms of the resulting lift, drag, moment, and thrust obtained from oblique shock theory, the Prandtl–Meyer equation, and the quasi-one-dimensional Rayleigh flow principle. Then the influence of active deformation on waverider control quality is considered by adjusting the c...

Case Report: The clinical implications of clozapine and cigarette smoking

INTRODUCTION Cigarette smoking is prevalent among psychiatric patients, with rates several times higher than the general population. As an example, up to 80% of schizophrenic patients smoke cigarettes. Clozapine is extensively metabolized by cytochrome P450 isoenzyme 1A2 and polycyclic aromatic hydrocarbons (PAHs) present in cigarette smoke are thought to induce CYP 1A2. Therefore concurrent smoking with clozapine can potentially lead to decreased clozapine levels and decreased efficacy, while smoking cessation can potentially lead to increased levels and toxicity. Enzyme induction has been reported to result in a 20 to 40% lower mean clozapine concentration in smokers compared to nonsmokers. We present a case of altered serum drug concentrations in association with changes in smoking status in a patient upon admission to a nonsmoking inpatient psychiatric facility.