Concentration Dependence Of Density Research Articles

Influence of Fe3O4 nanoparticles on structural, optical and magnetic properties of erbium doped zinc phosphate glass

Tunable modifications of physical and optical properties of metallic nanoparticles (NPs) embedded rare earth (RE) doped inorganic binary glasses are the key issue. Series of glass with composition (69-x)P2O5–30ZnO–1Er2O3–(x)Fe3O4, where 0 ≤ x ≤ 2 mol% containing Fe3O4 NPs are prepared by melt quenching method and characterized using XRD, UV–Vis–NIR, PL, TEM and vibrating sample magnetometer (VSM) techniques. The Fe3O4 NPs concentration dependent density, molar volume, structural, magnetic and optical properties are determined. The XRD pattern confirms the amorphous nature of all samples. The glass density is found increase and molar volume decrease with the increase of NPs concentration. The TEM micrographs reveal the presence of spherical NPs of average diameter ∼26 nm with homogenous distribution. The UV–Vis–NIR absorption spectra exhibit ten absorption bands centered at 376, 406, 448, 486, 522, 546, 652, 798, 976 and 1534 nm corresponding to the absorption from 4I15/2 ground state to various excited states of Er3+ ions. The optical band gap energy for direct (4.47–3.64 eV) and indirect (4.27–3.53 eV) transitions and Urbach energy (0.65–0.15 eV) are found to decrease with the increase of Fe3O4 contents. The decrease in band gap energy is ascribed to the creation of non bridging oxygen (NBO) ions in the glass network. The emission spectra at 478 nm excitations display two prominent peaks centered at 532 and 634 nm originate from 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. Furthermore, increasing NPs concentration dependent luminescence quenching is attributed to the energy transfer from the erbium ion to NPs. These glasses displaying ferrimagnetic behavior in the concentration range of 1.5–2 mol% of NPs verify the presence of iron oxide or ferrite in the glass sample are useful for magneto-optic devices.

Physico-chemical properties of the fullerenol-70 water solutions

The paper presents some data on physico-chemical study of the fullerenol-70 water solutions. The data on temperature dependence of solubility in water, concentration dependence of density, concentration dependence of the hydrogen ion concentration, specific conductivity, molar conductivity, dissociation constant, and dynamic light scattering are presented and characterized; composition of equilibrium solid phase in the fullerenol-70+ water binary system is determined.

Physico-chemical properties of the C60-tris-malonic derivative water solutions

The paper presents some data on the physico-chemical study of the C60-tris-malonic derivative water solutions. The data on the temperature dependence of solubility in water, concentration dependence of density, concentration dependence of the hydrogen ion concentration, specific conductivity, molar conductivity, dissociation constant, and dynamic light scattering are presented and characterized; composition of equilibrium solid phase in binary C60-tris-malonic derivative+water system is determined.

Effect of noncovalent basal plane functionalization on the quantum capacitance in graphene.

The concentration-dependent density of states in graphene allows the capacitance in metal-oxide-graphene structures to be tunable with the carrier concentration. This feature allows graphene to act as a variable capacitor (varactor) that can be utilized for wireless sensing applications. Surface functionalization can be used to make graphene sensitive to a particular species. In this manuscript, the effect on the quantum capacitance of noncovalent basal plane functionalization using 1-pyrenebutanoic acid succimidyl ester and glucose oxidase is reported. It is found that functionalized samples tested in air have (1) a Dirac point similar to vacuum conditions, (2) increased maximum capacitance compared to vacuum but similar to air, (3) and quantum capacitance "tuning" that is greater than that in vacuum and ambient atmosphere. These trends are attributed to reduced surface doping and random potential fluctuations as a result of the surface functionalization due to the displacement of H2O on the graphene surface and intercalation of a stable H2O layer beneath graphene that increases the overall device capacitance. The results are important for future application of graphene as a platform for wireless chemical and biological sensors.

Temperature and concentration dependences of density and refraction of aqueous duloxetine solutions

Present paper reports the measured densities (ρ) and refractive indices (nD) of aqueous solutions of Duloxetine drug in wide range of molal concentrations (m = 0.0101–0.1031 mol kg−1) and at different temperatures (297.15, 302.15, and 307.15 K). Apparent molar volumes (φv) of drug were calculated from density data and fitted to Masson’s relation \((\phi _\nu = \phi _\nu ^0 + S_\nu ^* \sqrt c )\) and partial molar volumes (φv0) were evaluated at different temperatures. Concentration dependence of refractive index (nD = Kc + nD0) at experimental temperature has been studied. Density and refractive index data has been used for the calculation of specific refractions (RD). Experimental (ρ and nD) and calculated (φv, φv0, and RD) properties have been interpreted in terms of concentration and temperature effects on structural fittings and drug-water interactions.

Fe-Si混合系融体のモル体積の組成依存性と局所構造

Fe-Si系融体のモル体積の組成依存性と局所構造との関連を明らかにするため，ガスジェット浮遊法を援用した放射光X線回折により高精度構造データを取得した．Si濃度が33～70at.%の組成において得られた構造因子は，短距離秩序の形成さらに中距離秩序の形成を示唆する特徴を示した．また，動径分布関数のピーク位置の組成変化から，Si濃度が増すにつれて融体中のFe-Si間の原子間相関が強くなり，Si濃度が80at.%近傍で平均原子間距離が最も短くなることを示した．さらに，Si濃度が増加するにつれてモル体積が増加するにも関わらず，平均原子間距離が縮むことに関して，原子間の結合の異方性を考慮することにより考察を行った．

Experimental study of the density and derived volumetric (excess, apparent, and partial molar volumes) properties of aqueous 1-propanol mixtures at temperatures from 298 K to 582 K and pressures up to 40 MPa

Densities of (water+1-propanol) mixtures have been measured over the temperature range from 298K to 582K and at pressures up to 40MPa using the constant-volume piezometer immersed in a precision liquid thermostat. The measurements were made for six compositions of (0.869, 2.465, 2.531, 7.407, 14.377, and 56.348)mol·kg−1 of 1-propanol. The expanded uncertainty of the density, pressure, temperature, and concentration measurements at the 95% confidence level with a coverage factor of k=2 is estimated to be 0.06%, 0.05%, 15mK, and 0.015%, respectively. The derived volumetric properties such as excess (VmE), apparent (VΦ), and partial (V¯2∞) molar volumes were calculated using the measured values of density for the mixture and for pure components (water and 1-propanol). The concentration dependences of the apparent molar volumes were extrapolated to zero concentration to yield the partial molar volumes of 1-propanol at infinite dilution (V¯2∞). The temperature, pressure, and concentration dependence of density and derived properties of the mixture were studied. All experimental and derived properties (excess, apparent, and partial molar volumes) were compared with the reported data by other authors. The small and negative values of excess molar volume for the mixtures were found at all experimental temperatures, pressures, and over the entire concentration range. The excess molar volume minimum is found at concentration about 0.4mole fraction of 1-propanol. The concentration minimum of the derived apparent molar volumes VΦ near the 2.5mol·kg−1 (dilute mixture) was observed.

Physical properties of glasses in the Ag2GeS3-AgBr system

Glasses have been prepared by quenching melts in the Ag2GeS3-AgBr system in a range of 0–53 mol % AgBr. The concentration dependences of density, microhardness, glass transition temperatures, and crystallization of alloys have been established. The conductivity of glasses has been investigated by the dc probe method in a range of 240–420 K. The models of the drift motion of silver and halogen ions have been proposed.

Relaxation oscillations between Marangoni cells and double diffusive fingers in a reactive liquid–liquid system

We study a novel kind of coupling in chemo-hydrodynamic pattern formation driven by a neutralization reaction along a plane interface separating two immiscible liquid phases. The neutralization reaction, during which a surface-active carboxylic acid is converted into a surface-active salt, gives rise to numerous cycles of relaxation oscillations between a fast cellular Marangoni convection with parallel-acting density plumes and a slow finger convection. By means of particle image velocimetry the dynamics of the sub-structured Marangoni cells are characterized while their geometrical aspects are analysed using shadowgraphy. Based on concentration-dependent density measurements and experiments with miscible solutions, the finger convection could be clearly identified as a double-diffusive phenomenon. Furthermore, the interaction of the sub-structured Marangoni cells with the density effects is examined.

Fullerenol Synthesis and Identification. Properties of the Fullerenol Water Solutions

This paper describes the synthesis and identification of the fullerenol, and data on the temperature dependence of solubility in water, concentration dependence of density, hydrogen ion concentration, molar conductivity, dissociation constant, and dynamic light scattering are presented. The composition of equilibrium solid phase in the binary fullerenol + water system is determined.

Density, Viscosity, Refractive Index and Conductivity of 1-Allyl-3-methylimidazolium Chloride + Water Mixture

The concentration dependence of density, viscosity, refractive index, and conductivity of aqueous solution of 1-allyl-3-methyl-imidazolium chloride ([Amim]Cl) at 298.15 K has been measured. It was shown that the density, as well as viscosity and refractive index, increased with increasing concentration of [Amim]Cl, while the conductivity increased sharply in the water-rich region and decreased in the [Amim]Cl-rich region. It was concluded that [Amim]Cl was a surfactant-like solvent, and the critical aggregation concentration of aqueous [Amim]Cl solution was obtained. The data obtained will play an important supplementary function in completion of the ionic liquids database.

Short-Range Atmospheric Dispersion of Carbon Dioxide

We present a numerical study aimed at quantifying the effects of concentration-dependent density on the spread of a seeping plume of CO2 into the atmosphere such as could arise from a leaking geologic carbon sequestration site. Results of numerical models can be used to supplement field monitoring estimates of CO2 seepage flux by modelling transport and dispersion between the source emission and concentration-measurement points. We focus on modelling CO2 seepage dispersion over relatively short distances where density effects are likely to be important. We model dense gas dispersion using the steady-state Reynolds-averaged Navier-Stokes equations with density dependence in the gravity term. Results for a two-dimensional system show that a density dependence emerges at higher fluxes than prior estimates. A universal scaling relation is derived that allows estimation of the flux from concentrations measured downwind and vice versa.

Densimetric study of solutions and fibers based on aromatic poly(amides)

The densimetric characteristics of solutions and fibers are obtained and analyzed for two aromatic poly(amides) poly(p-phenylene terephthalamide) and a copolymer composed of poly(p-phenylene terephthalamide) and poly(amide benzimidazole) units. For poly(p-phenylene terephthalamide) solutions in sulfuric acid in the concentration interval ranging from 3 to 19 wt %, the linear concentration dependences of density show the points of discontinuity, which correspond to the concentration boundaries of phase states: liquid crystalline and crystal solvate states. Under all of the processing conditions under study, Armos fibers are characterized by a low level of overall maximum porosity. This factor seems to be advantageous from the viewpoint of strength characteristics and other unique properties of fibers.

Isothermal compressibility in binary platinum based melts

The method based on concentration dependences of density and formation heat values for determination of fluctuation structure factors and isothermal compressibility has been used for binary Pt-Si and Pt-Sn melts.

Density and thermal expansion of liquid binary Al–Ag and Al–Cu alloys

Abstract Densities and thermal expansion coefficients of liquid Al–Ag and Al–Cu alloys were measured using the technique of electromagnetic levitation. This technique involves producing shadow images of the sample from which the volume is calculated by an image processing algorithm. Data was obtained at temperatures above the melting point. The concentration dependence of density and thermal expansion was studied for both systems. It was found for Al–Ag and Al–Cu that both density and thermal expansion can be related to a negative excess volume and its temperature coefficient.

Impact of Density Gradients on Flow-Through Dissolution in a Cylindrical Flow Cell

Measuring release rates for sparingly soluble compounds requires slow flow rates to achieve measurable eluent levels. However, flow rate cannot be reduced indefinitely because density gradients could measurably alter the drug release rate. Finite element simulations of convective diffusion/dissolution with an applied concentration-dependent density gradient reproduced the trends of the changes in dissolution rate on eluent flow rate which occur upon switching flow direction and sample cell orientation relative to gravitational field as observed in the literature[] employing a rectangular flow cell. The situation was experimentally reproduced using an implant obstruction placed centrally in a cylindrical flow cell.

Densities, Apparent Molar Volumes and Viscosities of Concentrated Aqueous NaNO3 Solutions at Temperatures from 298 to 607 K and at Pressures up to 30 MPa

Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg−1) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg−1) NaNO3(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for the density measurements and 298–576 K for the viscosity measurements. The total uncertainty of density, viscosity, pressure, temperature and composition measurements were estimated to be less than 0.06%, 1.6%, 0.05%, 15 mK and 0.02%, respectively. The temperature, pressure and concentration dependence of density and viscosity of NaNO3(aq) solutions were studied. The measured values of density and viscosity of NaNO3(aq) were compared with data and correlations reported in the literature. Apparent molar volumes were derived using the measured density values. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for strong electrolytes. The values of the viscosity A-, B-, D- and F-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η0) of NaNO3(aq) solutions were evaluated as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data.

Modelling the thermosolutal convection, shrinkage flow and grain movement of globular equiaxed solidification using a three phase model

A three phase volume averaging model has been developed to simulate globular equiaxed solidification, the three phases being liquid, solid and air. The basic conservation equations of mass, momentum and enthalpy have been solved for each phase, and the thermal and mechanical (drag force) interactions among the phases have been considered. Grain nucleation, growth rate (mass exchange), solute partitioning at the liquid/solid interface and solute transport have also been accounted for. Due to its low density, the air phase floats always at the top region, forming a definable air/liquid melt interface, i.e. free surface. By tracking this free surface, the shrinkage cavity in an open casting system can be modelled. As the temperature and concentration dependent density and solidification shrinkage are explicitly included, the thermosolutal convection, together with feeding flow and grain movement can be taken into account. This paper focuses on the model description; preliminary results on a benchmark ingot casting (Al–4Cu) are presented and discussed.

Transport with a Very Low Density Contrast in Hele–Shaw Cell and Porous Medium: Evolution of the Mixing Zone

The optimal concentration of a blue dye solution with 'tracer' properties, enabling a pollutant to be marked was determined by the use of numerical, theoretical and experimental approaches. Experimental investigations were performed on a transparent Hele–Shaw cell and the concentration distribution was analyzed using an optical technique based on dye light absorption properties. The injected optimal concentration was established thanks to a theoretical and experimental study carried out on the output signal dynamics. Using the same experimental conditions, numerical simulations were performed. The very good agreement between the data (experimental and numerical) clarified that: (i) the choice of the blue dye optimal concentration was valid and (ii) the concentration-dependent density should not be neglected in flow and transport equations even if it concerns a so-called 'tracer'. Following this remark, a theoretical aspect was developed in order to determine the analogous conditions between a Hele–Shaw cell and a porous medium for the variable density transport phenomenon. The structure of the concentration-dependent dispersion tensor used in the numerical code was obtained by homogenizing the Stokes flow of a bi-component mixture. The numerical results show that, as long as the tracer density does not exceed a certain value, it is not necessary to take into account a density contrast in terms of the dispersion tensor. The classical form of the Taylor dispersion tensor can be used successfully.

Description of binary liquid mixtures transport through non-porous membrane by modified Maxwell–Stefan equations

This paper deals with a description of transport parameters during pervaporation of binary liquid mixture through non-porous polymer membrane. The main task of this work is the application of the model that would be able to describe the transport of the penetrant in the membrane. The influence of the C-number of aliphatic alcohols on transport parameters is also under study. The concentration dependent density of the membrane, vapor sorption isotherms, the dependence of pure component diffusion coefficients on their concentration in the membrane and the dependence of the solubility of liquid binary mixture in a membrane was necessary to determine experimentally. All mention dependencies were mathematically described and then introduced into modified Maxwell–Stefan equations. The model was used for the liquid binary mixtures (ethanol, propan-1-ol, butan-1-ol with toluene) and the low-density polyethylene membrane at 25 °C. Pervaporation data for all the three systems were measured in order to calculate coupled diffusion coefficient and to compare the model with the experiment. The dependencies of pervaporation fluxes and weight fraction of preferable penetrant in permeate on concentration of preferable penetrant in the feed are compared with the calculations based on the first Fick’s law with constant diffusion coefficient and modified Maxwell–Stefan equations.