Concentration Dependence Of Properties Research Articles

The molecular basis for hydrodynamic properties of PEGylated human serum albumin

Polyethylene glycol (PEG) conjugation provides a protective modification that enhances the pharmacokinetics and solubility of proteins for therapeutic use. A knowledge of the structural ensemble of these PEGylated proteins is necessary to understand the molecular details that contribute to their hydrodynamic and colligative properties. Because of the large size and dynamic flexibility of pharmaceutically important PEGylated proteins, the determination of structure is challenging. In addition, the hydration of these conjugates that contain large polymers is difficult to determine with traditional methods that identify only first shell hydration water, which does not account for the complete hydrodynamic volume of a macromolecule. Here, we demonstrate that structural ensembles, generated by coarse-grained simulations, can be analyzed with HullRad and used to predict sedimentation coefficients and concentration-dependent hydrodynamic and diffusion nonideality coefficients of PEGylated proteins. A knowledge of these concentration-dependent properties enhances the ability to design and analyze new modified protein therapeutics. HullRad accomplishes this analysis by effectively accounting for the complete hydration of a macromolecule, including that of flexible polymers.

Mitigating Joule heating in smart nanochannels: Evaluating the efficacy of AC vs. DC fields

This study delves into the profound implications of different electric field types, namely DC and AC with a sinusoidal waveform, on ion transport within intelligent soft nanochannels, aiming to mitigate Joule heating effects. The investigation considers temperature- and concentration-dependent properties and explores their impact on ionic selectivity, rectification factor, Joule heating, and viscosity dissipation in conical soft nanochannels. Operating in both co-current and counter-current modes, the study accounts for the nanochannel's coating with a dense and strongly negatively charged polyelectrolyte layer, addressing the ionic partitioning effect. Numerically solving the Poisson-Nernst-Planck, Navier-Stokes, and energy equations, the study reveals a significant alignment of Joule heating and viscosity dissipation with ionic current, emphasizing the influence of concentration and temperature ratios. Notably, the bidirectional AC field demonstrates a remarkable 85.51% and 71.72% reduction in Joule heating in co-current and counter-current modes, respectively, compared to DC. These findings highlight the significant impact of the AC field on thermal dynamics within nanochannels. In summary, our study offers essential insights into optimizing nanofluidic systems by effectively balancing ion transport efficiency and thermal effects across various electrical field scenarios. These findings directly address the critical challenge of managing Joule heating in intelligent nanochannels, which is essential for enhancing the performance of lab-on-a-chip devices in sensitive biomedical applications.

Theoretical Investigation of the Thermodynamic Properties of Lead-free Ternary Alloys Sn-Sb-Bi and their Subsystems

The concentration-dependent properties, like the constituents’ activities for the binary liquid alloys like Sb-Sn at 905 K, Bi-Sn at 600 K, and Bi-Sb at 1200 K, and the integral Gibbs free energy of mixing, ΔGXS, of the correspondent alloys were computed using the molecular interaction volume model (MIVM). Further, the model has been used to compute the activities of the component Sn in the ternary Sn-Sb-Bi system at 900K at the three cross-sections, i.e., Sb:Bi = 1:3, 1:1, and 3:1. The theoretical data have been analyzed with the corresponding experimental data accessible in the literature. An acceptable concurrence has been obtained, with some inconsistencies. The activities of the ternary alloys along the three cross-sections, i.e., Sb:Bi = 1:3, 1:1, and 3:1, show that the deviations change from positive to negative with increasing Sb content. The results confirm that MIVM is a good model for estimating the thermodynamic properties of binary and ternary systems.

Structural properties and epitaxial relation of cubic rock salt ScxAl1−xN/ScN/Si

ScN in the rock salt structure is a well-investigated material due to its desirable properties like the high hardness or large thermal conductivity. Recent computations by Adamski et al. [Appl. Phys. Lett. 115, 232103 (2019)] showed that ScN/GaN heterostructures exhibit an outstanding polarization gradient which would be beneficial for polarization induced electron gases. The pseudobinary semiconductor ScxAl1−xN, when maintaining the cubic rock salt structure, could be beneficial for tailoring the polarization gradient using the Sc dependency of material properties. The structural properties of rs-ScxAl1−xN are not fully discovered yet, thus in this work, DC-magnetron sputtered cubic rock salt ScxAl1−xN thin films with 0.55<x<1.00 were grown and analyzed on ScN(111)/Si(111). The epitaxial relation of ScN(111) thin films on the Si(111) substrate is determined to be ScN[110] ∥ Si[100]. Furthermore, concentration dependent properties like the lattice parameter of ScxAl1−xN were measured [a(ScN) = 4.50 Å, a(Sc0.55Al0.45N) = 4.30 Å] and the stress σ within the layers was determined. The crystal quality was evaluated using ω-scans, revealing FWHM=1.14° for Sc0.95Al0.05N. The diameters of the columns were determined by atomic force microscopy and scanning electron microscopy and they are range from 34 to 59 nm for 0.55<x<1.00. At x=0.55, ScxAl1−xN columns in the hexagonal wurtzite as well as cubic rock salt structure were detected. This information about the structural specifications of ScxAl1−xN in the rock salt structure forms the basis for further investigations and experimental confirmation of the electric properties of ScN/GaN heterostructures or even a ScxAl1−xN/GaN based approach for improved structures for high-electron-mobility transistors.

Phenomenological interpretations of the mechanism for the concentration-dependent positive effect of antibiotic lincomycin on Streptomyces coelicolor A3(2).

The antibiotic lincomycin binds to the 23S ribosomal RNA peptidyl transferase loop region to inhibit protein synthesis. However, lincomycin can also stimulate the growth and secondary metabolism of actinomycetes in a concentration-dependent manner. In Streptomyces coelicolor A3(2), lincomycin stimulates the production of the blue-pigmented antibiotic actinorhodin at concentrations below the minimum inhibitory concentration. To better understand the molecular mechanism underlying these concentration-dependent positive effects, this study investigated how the target molecule, the ribosome, undergoes dynamic changes in the presence of lincomycin and explored the ribosome-related factors involved. Lincomycin, at a concentration that stimulates actinorhodin production of S. coelicolor A3(2), could restore temporarily arrested ribosome function by utilizing ribosome-related proteins and translation factors, presumably under the control of the transcription factor WblC protein that confers intrinsic resistance to multiple translation-inhibiting antibiotics, to eventually produce stable and active ribosomes even during the late growth phase. This qualitatively and quantitatively positive ribosome alteration can be advantageous for producing actinorhodin biosynthetic enzymes. A series of gene expression and biochemical analyses revealed that lincomycin at the concentration that induces ribosomal stabilization in S. coelicolor A3(2) could influence the localization of the 20S proteasome-related proteins, resulting in reduced proteasome activity. These findings suggest that the functional analysis of 20S proteasome represents a potential pivotal challenge for understanding the molecular mechanism of ribosome stabilization induced by lincomycin. Therefore, as lincomycin can dynamically alter its target molecule, the ribosome, we discuss the future issues and prospects for an increased understanding of the concentration-dependent properties of antibiotics. IMPORTANCE Antibiotics were originally defined as chemical compounds produced by a microbe that inhibits the growth of other microbes. However, an unexplained effect of this is that a low concentration of antibiotics, such as those below the minimum inhibitory concentration, can positively affect microbial growth and metabolism. The secondary metabolic activation of streptomycetes in the presence of the translation-inhibiting antibiotic lincomycin illustrates the concentration-dependent positive effect of the antibiotic. The significance of this study is that the phenomenological interpretation of the molecular mechanism of the concentration-dependent positive effect of lincomycin in Streptomyces coelicolor A3(2) has provided novel insight into the possible role of antibiotics in making their target molecules stable and active with the assistance of various related factors that benefit their function. Further exploration of this idea would lead to an essential understanding of antibiotics, including why actinomycetes make them and their role in nature.

Hygromechanical Behavior of Polyamide 6.6: Experiments and Modeling.

This paper investigates water absorption in polyamide 6.6 and the resulting hygroscopic swelling and changes in mechanical properties. First, sorption and swelling experiments on specimens from injection molded plates are presented. The observed swelling behavior is dependent on the melt flow direction of the injection molding process. Additionally, thermal analysis and mechanical tensile tests were performed for different conditioning states. The water sorption is accompanied by a decrease in the glass transition temperature and a significant reduction in stiffness and strength. Next, a sequentially coupled modeling approach is presented. A nonlinear diffusion model is followed by mechanical simulations accounting for swelling and concentration-dependent properties. For the mechanical properties, the notion of a "gap" temperature caused by the shift of the glass transition range due to water-induced plasticization is employed. This model enables the computation of local moisture concentration fields and the resultant swelling and changes in stress-strain behavior.

One-pot synthesis of aggregation-induced multi-emission and solid-state room-temperature-phosphorescence carbon dots

Multi-emission carbon dots (M-CDs) have broad applications. However, reports of the synthesis of M-CDs and their emission mechanism are limited. In this study, M-CDs with three emissions are synthesized by a one-pot solvothermal method, and the luminescence mechanism is investigated in detail. The prepared M-CDs show significant concentration-dependent properties. For high-concentration M-CDs (HC CDs), the surface-defect and carbon-core luminescence states are related to emission centers at 423 and 586 nm, respectively. The emission center at 493 nm are mainly due to the self-absorption of M-CDs. Conversely, low-concentration M-CDs (LC CDs) have 423 and 586 nm emissions. The blue CDs (B-CDs) and red CDs (R-CDs) are extracted from the prepared M-CD solution. The structural and optical properties indicate that the 493 nm peak is related to aggregation and self-absorption between B-CDs and R-CDs in HC CDs. Surprisingly, solid CDs (S-CDs) with solid-state room-temperature phosphorescence (RTP) are simultaneously obtained during the preparation of the M-CDs. The mechanism investigation results show that S-CDs are composed of CDs and NaHCO3, and NaHCO3 acts as an oxygen barrier to prevent the quenching of the triplet and rigidly holds the luminescent guests to suppress vibrational dissipation. The M-CDs are successfully applied to detect Morin, while the S-CDs are demonstrated for optical anti-counterfeiting applications.

Structural electroneutrality in Onsager–Stefan–Maxwell transport with charged species

We present a method to embed local electroneutrality within Onsager–Stefan–Maxwell electrolytic-transport models, circumventing their formulation as differential systems with an algebraic constraint. Flux-explicit transport laws are developed for general multicomponent electrolytes, in which the ionic conductivity, component diffusivities, and transference numbers relate to Stefan–Maxwell coefficients through invertible matrix calculations. A construction we call a ‘salt–charge basis’ implements Guggenheim’s transformation of species electrochemical potentials into combinations describing a minimal set of neutral components, leaving a unique combination associated with electricity. Defining conjugate component concentrations and fluxes that preserve the structures of the Gibbs function and energy dissipation retains symmetric Onsager reciprocal relations. The framework reproduces Newman’s constitutive laws for binary electrolytes and the Pollard–Newman laws for molten salts; we also propose laws for salt solutions in two-solvent blends, such as lithium-ion-battery electrolytes. Finally, we simulate a potentiostatic Hull cell containing a non-ideal binary electrolyte with concentration-dependent properties.

Numerical analysis of concentration-dependent physical properties and bioconvection for Williamson nanofluid flow due to stretching/ shrinking sheet

In this paper, an investigation into Williamson nanofluid stagnation point flow of nano-biofilm over a stretching/ shrinking sheet with chemical reaction is performed. Moreover, the impact of cylindrical-shaped nanoparticles, activation energy, and bioconvection has been considered. The fluid’s fluctuating transport properties (dynamic viscosity, heat conductivity, nanoparticle mass diffusivity) and microorganism diffusivity are evaluated. The nonlinear systems of partial differential equations are transformed into nonlinear differential equations via the implementation of similarity transformations. The shooting approach and RK-4 technique are used for this investigation. The impacts of various fluid transport characteristics and various factors on patterns of velocity, temperature, the concentration of nanoparticles, and motile density are described. The Brownian motion, heat source and thermophoresis parameters all lead to a more consistent temperature profile being observed. It is seen that concentration-dependent properties decrease the velocity profile while the temperature, concentration, and motile density profiles increase. Also, the physical quantities decrease with the rising values of concentration-dependent properties.

The significance of Magnetohydrodynamics sutterby nanofluid flow with concentration depending properties across stretching/ shrinking sheet and porosity

In this study, the impact of activation energy and transiting parameters on the two-dimensional stagnation point flow of magnetized Sutterby nanofluid of nano-biofilm incorporating with microorganisms over the porous surface has been examined. Prior research suggests that both the fluid viscosity and thermal conductance are temperature-dependent. Also, the effects of solutal concentration on fluid viscosity, heat capacity and nanofluid properties have been elaborated. In recent years, numerous technical strategies comprising hydromagnetic fluxes and thermal intensification in porosity media, like molding, condenser heat exchanger, liquefied metal filtration, fusion control and nuclear reactor coolant, have been addressed. According to numerous empirical studies, the viscosity and thermal conductivity of the nanoparticles are largely dependent on the intensity of nanoparticles rather than the temperature. The classical RK-4 method with shooting technique has been used. The significance of involving parameters in the domains of heat, velocity, density and concentration has been illustrated. The effect of nondimensional parameters on the skin friction factor, Nusselt number and Sherwood number has been discussed. The nanoparticle density increases with the activating energy effects and thermophoresis factor and rapidly decreases for Lewis number and Brownian factor. The velocity, temperature and concentration profiles increase as the concentration-dependent properties do, but all physical quantities deteriorate for all concentration-varying factors.

On the analogy between the restricted primitive model and capacitor circuits. Part II: A generalized Gibbs-Duhem consistent extension of the Pitzer-Debye-Hückel term with corrections for low and variable relative permittivity

We present a novel, thermodynamically consistent modification of the Pitzer-Debye-Hückel term and its extension for concentration dependent density, molar mass and relative permittivity. This extension is validated for ionic liquids by comparison with a reference model from the literature and, in contrast to similar extensions, also applied to conventional salts with small spherical ions in aqueous, mixed and non-aqueous solvents. The central novelty is the inclusion of a modified parameter of closest approach, which improves the overall qualitative performance of the Pitzer-Debye-Hückel term over the complete relative permittivity range. Gibbs-Duhem consistency is retained in the modified extension and sample calculations for aqueous [BMIM][BF4] and aqueous NaCl are provided. The novel, modified and extended term with concentration dependent properties is combined with the predictive COSMO-RS-ES model for the calculation of phase equilibria and activity coefficients in electrolytes with conventional salts. The performance of the COSMO-RS-ES model for predictions of salt solubility in fully non-aqueous media improves significantly upon introduction of concentration dependent properties within the long-range electrostatics. Modelling performance with the modified extended Pitzer-Debye-Hückel term outperforms modelling with the unmodified extensed term as well as with the conventional term. The correlated relative permittivity of the mixture is overestimated with respect to experimental values and kinetic depolarization effects provide a plausible explanation for this observation. Overall, our results support the consistent introduction of concentration dependent properties within the electrostatic theory in order to improve the modelling of electrolytes with particular emphasis on non-aqueous electrolytes.

The concentration effects on structural and magnetic properties of Fe2V1-xMnxGe Heusler alloys

This study presents the concentration-dependent structural, morphological, and magnetic properties of Fe2V1-xMnxGe Heusler alloys (x = 0.0, 0.25, and 0.50) have not been studied previously in the literature, and are investigated by using X-ray Diffractometer, Scanning Electron Microscope (SEM), and Physical Properties Measurement System (PPMS). We observed from the X-ray diffraction measurements that (except x = 0) Fe2V1-xMnxGe samples have had L21-type crystal structure, matching well with the literature. In all SEM images, some holes and crack-type formations are observed. Increasing Mn content in Fe2V1-xMnxGe Heusler alloys can effectively inhibit grain boundary migration. Except for Fe2VGe, the other alloys in the series are investigated to be soft ferromagnets at 5 K with saturation magnetic moment. The (M-H) graphs especially for Fe2V0.75Mn0.25Ge and Fe2V0.5Mn0.5Ge measured at 5 K reveal almost no coercive fields and easy magnetization. Namely, the system easily saturates without needing any high fields. The obtained results show that these new samples may be suitable candidates for technological applications.

Combined influence of concentration-dependent properties, local deformation and boundary confinement on the migration of Li-ions in low-expansion electrode particle during lithiation

In this article, a low expansion electrode particle is investigated for mechanical stresses during lithiation with intrinsic and extrinsic factors included. The stress states are estimated with local deformation, concentration dependent properties, and external constraints. It is observed that lithiation of an unconstrained electrode particle lead to reduced concentration gradient of Li-ions with increase in stress magnitude for a case where the particle show concentration dependent stiffening response. Whereas, the constrained expansion of the same electrode particle result in reduced and elevated concentration gradient at near-field and far-field locations, respectively. Influence of charging rate is also reported wherein limiting stress (threshold limit) is observed with increasing charging rate. Further, at elevated charging rates, a drastic reduction in concentration gradient is observed at the surface of the electrode particle.

Role of Magnetic Coupling in Photoluminescence Kinetics of Mn2+-Doped ZnS Nanoplatelets.

Mn2+-doped semiconductor nanocrystals with tuned location and concentration of Mn2+ ions can yield diverse coupling regimes, which can highly influence their optical properties such as emission wavelength and photoluminescence (PL) lifetime. However, investigation on the relationship between the Mn2+ concentration and the optical properties is still challenging because of the complex interactions of Mn2+ ions and the host and between the Mn2+ ions. Here, atomically flat ZnS nanoplatelets (NPLs) with uniform thickness were chosen as matrixes for Mn2+ doping. Using time-resolved (TR) PL spectroscopy and density functional theory (DFT) calculations, a connection between coupling and PL kinetics of Mn2+ ions was established. Moreover, it is found that the Mn2+ ions residing on the surface of a nanostructure produce emissive states and interfere with the change of properties by Mn2+-Mn2+ coupling. In a configuration with suppressed surface contribution to the optical response, we show the underlying physical reasons for double and triple exponential decay by DFT methods. We believe that the presented doping strategy and simulation methodology of the Mn2+-doped ZnS (ZnS:Mn) system is a universal platform to study dopant location- and concentration-dependent properties also in other semiconductors.

An Analysis for Variable Physical Properties Involved in the Nano-Biofilm Transportation of Sutterby Fluid across Shrinking/Stretching Surface.

In this article, we explore how activation energy and varied transit parameters influence the two-dimensional stagnation point motion of nano-biofilm of Sutterby fluids incorporating gyrotactic microbes across a porous straining/shrinking sheet. Prior investigations implied that fluid viscosity as well as thermal conductance are temperature based. This research proposes that fluid viscosity, heat capacity and nanofluid attributes are all modified by solute concentration. According to some empirical research, the viscosity as well as heat conductivity of nanoparticles are highly based on the concentration of nanoparticles instead of only the temperature. The shooting approach with the RK-4 technique is applied to acquire analytical results. We contrast our outcomes with those in the existing research and examine their consistency and reliability. The graphic performance of relevant factors on heat, velocity, density and motile concentration domains are depicted and discussed. The skin friction factor, Nusselt number, Sherwood number and the motile density are determined. As the concentration-dependent properties are updated, the speed, temperature, concentration and motile density profiles are enhanced, but for all concentration-varying factors, other physical quantities deteriorate.

Surface effects on buckling of nanowire electrode

Nanowire-based electrodes have attracted much attention due to their high surface energy, short distance for lithium insertion, and the ability to accommodate the enormous strain. However, the buckling behavior may occur during lithiation for such wire-like electrodes, which would lead the battery performance to deteriorate. Therefore, it is vital to quantitatively understand the mechanism about the bucking behavior of the nanowire-based electrodes. Although the buckling behavior of wire-like electrode has been extensively studied in the past few decades, the influence of surface effect on it has not yet been thoroughly explored. For this purpose, a theoretical model of surface effects on buckling of nanowire electrode is presented by taking into account the lithium diffusion, stress, and concentration-dependent elastic properties. Based on the established model, the effects of the residual surface tension and elastic hardening/softening coefficients on buckling are investigated. The results show that surface effects can improve the mechanical reliability, thus delaying the critical buckling time of nanowire electrode. In addition, it is indicated that the surface effects depend on the radius size and slenderness ratio of the nanowire electrode, specifically, the smaller the radius size and the larger the slenderness ratio, the greater the influence of the surface effect is. Furthermore, compared with elastic hardening, with the participation of surface effects, the larger the elastic softening coefficient, the longer it takes for the nanowire electrode to reach the buckled state, and the better the stability of the electrode is. The novelty of this work is that the proposed models highlight the importance of surface effects on buckling of nanowire electrode. These findings provide a prospective insight into the designing of higher structural reliability of electrode.

Red and near-infrared emitting phosphors based on Eu3+- or Nd3+-doped lanthanum niobates prepared by the sol–gel route

We have evaluated the structural and luminescence properties of Eu3+- or Nd3+-doped lanthanum niobate systems synthesized via a sol-gel route and containing different dopant contents. XRD analysis revealed that the orthorhombic La3NbO7 and monoclinic LaNbO4 crystalline phases were present in all the samples, regardless of the dopant concentration. The excitation spectra of the samples displayed a broad band due to Nb5+→O2- charge transfer; this band was quite sensitive to the increasing Eu3+ content. The photoluminescence emission spectra of the samples with a lower Eu3+ content showed that Eu3+ occupied both crystalline phases. However, when the Eu3+ content increased, these ions preferentially occupied the C2 symmetry sites in the LaNbO4 host lattice. There was no emission quenching for the Eu3+-doped samples with a Eu3+ content as high as 20 mol%. The emission spectra of the Nd3+-doped samples displayed an intense emission band in the NIR-II biological window under NIR-I excitation, at 808 nm. In the case of the samples with a lower Nd3+ content, Nd3+ occupied distinct symmetry sites in La3NbO7. In contrast, in the samples with a higher Nd3+ content, these ions preferentially occupied LaNbO4 sites. The Nd3+ concentration that quenched emission in the Nd3+-doped samples was about 2.6 mol%, due to Nd3+-Nd3+ cross-relaxation processes. On the basis of these findings, the Eu3+-doped samples explored herein have promising applications in the lighting field, whereas the Nd3+-doped samples have potential use as solid-state lasers and biomarkers.

Impacts of the temperature-dependent properties on ion transport behavior in soft nanochannels

The influence of the temperature- and concentration-dependent properties, derived from the gradients of temperature and concentration, on the ionic selectivity, ionic current rectification, Joule heating, and viscosity dissipation in conical soft nanochannels was numerically investigated. Both co-current an counter-current modes of operation, in terms of implementing temperature- and concentration gradients, were considered. Since it was assumed that the nanochannel is coated with a dense polyelectrolyte layer, the ionic partitioning effect was also considered. Through adopting a numerical approach, Poisson–Nernst–Planck, Navier–Stokes, and energy equations were solved at steady-state conditions by considering different values of permittivity, diffusivity, and viscosity for the PEL and the electrolyte. The most important result of this study is that under an applied voltage, by increasing the temperature and concentration ratios, the Joule heating increased. For instance, at counter-current mode, by increasing the concentration ratio from 1 to 100, the Joule heating increased from 1 nW to 3.5 nW. It was also realized that upon applying an external voltage of Vapp = − 5 V, the Joule heating reaches a value of 130 nW. As such, it was concluded that the lack of control in the generation of Joule heating would harm the transport behavior of ionic species within soft nanochannels.

Impact of mechanical stiffening and softening on the spatial distribution of lithium ions in spherical electrode particle under galvanostatic charging

This article investigates the lithiation of low-expansion electrode particles with concentration-dependent properties. The conventional electrochemical coupled stress equations do not take into account concentration dependency, especially for particles with a low volume of expansion, as they are assumed to have no impact on the lithium-ion (Li-ion) migration. However, considerable changes are observed in the present study when this factor is included. The Li-ion concentration gradient is observed to decrease with stiffening and increase with softening in an electrode particle. The stresses at the center of the particle increase with stiffening and reduce with the softening. It is observed that the effect of concentration-dependent elastic modulus on the concentration gradient of lithium ions at the surface of the particle is more prominent at higher charging rates. The stresses in the electrode particle are observed to increase in proportion to an increase in the charging rate up to a critical limit beyond which its magnitude reduces.

Composition dependent density of ternary aqueous solutions of ionic surfactants and salts

Surfactants exist in atmospheric aerosols mixed with inorganic salts and can significantly influence the formation of cloud droplets due to bulk–surface partitioning and surface tension depression. To model these processes, we need continuous parametrizations of the concentration dependent properties of aqueous surfactant–salt solutions for the full composition range from pure water to pure surfactant or salt. We have developed density functions based on the pseudo-separation method and Young’s mixing rule for apparent partial molal volumes for solutions that mimic atmospheric droplets of marine environments. The developed framework requires only model parameters from binary water–salt and water–surfactant systems and includes the effect of salinity on micellization with composition-dependent functions for the critical micelle concentration (CMC). We evaluate different models and data available in the literature to find the most suitable representations of the apparent partial molal volume of sodium chloride (NaCl) in aqueous solutions and the CMC of selected atmospheric and model surfactants in pure water and aqueous NaCl solutions. We compare model results to experimental density data, available in the literature and obtained from additional measurements, for aqueous solutions containing one of the ionic surfactants sodium octanoate, sodium decanoate, sodium dodecanoate or sodium dodecylsulfate mixed with NaCl in different relative ratios. Our model follows the experimental trends of increasing densities with increasing surfactant concentrations or increasing surfactant–salt mixing ratios both, below and above the CMC, capturing the effect of the inorganic salt on the surfactant micellization.