Dispersive Component Research Articles

Alternative modification by grafting in bamboo cellulose nanofibrils: A potential option to improve compatibility and tunable surface energy in bionanocomposites

Chemical modification in surface of cellulose nanofibrils CNFs (20 nm) from an endemic and non-significant value-added, Argentine bamboo, was developed. The modification in the CNFs was carried out with three simple routes using a low molecular weight polylactic acid synthesized in our laboratory (PLA1). The first step comprises of protection of the hydroxyl groups of PLA1 through a benzoylation (PLA1Bz). The next step consisted of the activation of carboxyl groups using thionyl chloride and the last reaction was the grafting of the modified PLA onto the CNFs (PLA1Bz-g-CNF). The covalently functionalization is confirmed by spectroscopically techniques as well as PLA1Bz-g-CNFs were characterized by thermal analyses. The PLA1Bz-g-CNFs were taken up such as nanocharges to improve properties of compatibilization and changing surface properties in films based on PLA. The comparison between the films with PLA1Bz-g-CNFs with respect to the physic mixture of the components (PLA1Bz/CNF), shows an improvement in the thermal, mechanical, and surface properties of the material, particularly when 5% of PLA1Bz-g-CNFs was added. The dispersive (γS D) component of film is increased in 36.1 mN/m respect to 29.3 mN/m from the films obtained with the physic mixture nanofibrils without modification and a plasticizing effect was noticed in the final material.

Reactive Cellu-mers-A Novel Approach to Improved Cellulose/Polymer Composites.

In this paper, we describe a novel method for preparation of polymer composites with homogeneous dispersion of natural fibers in the polymer matrix. In our approach, Williamson ether synthesis is used to chemically modify cellulose with polymerizable styrene moieties and transform it into a novel multifunctional cellu-mer that can be further crosslinked by copolymerization with styrene. Reactions with model compounds (cellobiose and cellotriose) successfully confirm the viability of the new strategy. The same approach is used to transform commercially available cellulose nanofibrils (CNFs) of various sizes: Sigmacell and Technocell™ 40, 90 and 150. The styrene-functionalized cellulose oligomers and CNFs are then mixed with styrene and copolymerized in bulk at 65 °C with 2,2′-azobisisobutyronitrile as initiator. The resulting composites are in a form of semi-interpenetrating networks (s-IPN), where poly(styrene) chains are either crosslinked with the uniformly dispersed cellulosic component or entangled through the network. Non-crosslinked poly(styrene) (31–41 w%) is extracted with CHCl3 and analyzed by size-exclusion chromatography to estimate the extent of homopolymerization and reveal the mechanism of the whole process. Electron microscopy analyses of the networks show the lack of cellu-mer agglomeration throughout the polymer matrix. The homogeneous distribution of cellulose entities leads to improved thermal and mechanical properties of the poly(styrene) composites compared to the physical mixtures of the same components and linear poly(styrene) of similar molecular mass.

High-dispersion TIR-GRISMs with flattened angular dispersion profile

Modern grating imaging spectrographs typically show aberrations due to the nonlinear dependence of angular dispersion on wavelength. This error can be reduced by a combination of diffracting and refracting components (grating and prism). Here, we present a dispersive optical component, namely, total internal reflection (TIR) grating + prism, with a grating attached to one facet of a prism. The elements work within the limit of TIR and exhibit three advantages compared to standard diffraction gratings: first, high diffraction efficiency up to 98%; second, enormous angular dispersion up to 0.75 ∘ n m − 1 ; and third, a nearly constant angular dispersion profile. As an example, the fabrication of such a disperser designed for the short-wave infrared2 spectral range is demonstrated. We report on details of the manufacturing process, which relies on a dedicated combination of technologies, i.e., electron beam lithography, atomic layer deposition, and hydrophilic direct bonding.

The surfactant Dioctyl Sodium Sulfosuccinate (DOSS) exposure causes adverse effects in embryos and adults of zebrafish (Danio rerio)

Dioctyl Sodium Sulfosuccinate (DOSS, CAS 577-11-7) is a chemical emulsifying surfactant that is widely used in the food and the cosmetic industry, and it is also the major component of the crude oil chemical dispersant Corexit™. Despite of its wide use, the studies related to its negative effect have been evaluated mainly in marine environments showing that DOSS is highly bioactive, extremely low volatile, and potential to persist in the environment longer than other dispersant components. Up to date, there is no available information of DOSS concentration in freshwater environments, little is known about its downstream fate after excretion and its effect on freshwater organisms. The objective of this study was to evaluate the effect of DOSS at different concentrations in embryos and adults of zebrafish Danio rerio in an acute-static bioassays of 96 h. The median lethal concentration in embryos was 33.3 mg/L. Malformations started to be observed at 10 mg/L. In adults, the gene expression analysis in gill tissues showed a deregulation in genes associated with the antioxidant system and the nucleotide excision repair mechanism. Additionally, Micronuclei (DNA damage) in erythrocytes, and fat degeneration in liver, hypertrophy and hyperplasia in gills, and hyaline drops in kidney tissues were also observed. In conclusion, the concentrations of DOSS evaluated here would be of health relevance to fish based on morphological alterations in embryos and changes in the gene expression profile, DNA damage and tissue impairment in adults.

Progress in Electrohydrodynamic Atomization Preparation of Energetic Materials with Controlled Microstructures.

Constructing ingenious microstructures, such as core–shell, laminate, microcapsule and porous microstructures, is an efficient strategy for tuning the combustion behaviors and thermal stability of energetic materials (EMs). Electrohydrodynamic atomization (EHDA), which includes electrospray and electrospinning, is a facile and versatile technique that can be used to process bulk materials into particles, fibers, films and three-dimensional (3D) structures with nanoscale feature sizes. However, the application of EHDA in preparing EMs is still in its initial development. This review summarizes the progress of research on EMs prepared by EHDA over the last decade. The morphology and internal structure of the produced materials can be easily altered by varying the operation and precursor parameters. The prepared EMs composed of zero-dimensional (0D) particles, one-dimensional (1D) fibers and two-dimensional (2D) films possess precise microstructures with large surface areas, uniformly dispersed components and narrow size distributions and show superior energy release rates and combustion performances. We also explore the reasons why the fabrication of 3D EM structures by EHDA is still lacking. Finally, we discuss development challenges that impede this field from moving out of the laboratory and into practical application.

Comparative study of nitrogen doped multi walled carbon nanotubes grafted with carboxy methyl cellulose hybrid composite by inverse gas chromatography and its UV photo detectors application

In this present work, the synthesis of nitrogen doped multi walled carbon nanotubes (N-MWCNTs) grafted Sodium-carboxy methyl cellulose (Na-CMC) hybrid composite was carried out via thermal reduction process. The hybrid composites were thermodynamically characterized by inverse gas chromatography (IGC) and compared to Na-CMC particles. The results were obtained by using 14 different IGC methods and models. We proved that the free energy of adsorption of the different solvents on N-MWCNTs-Na-CMC surface was equal to the summation of both free enthalpies of the solvents separately adsorbed on N-MWCNT and on Na-CMC surfaces. The London dispersive surface free energy of different materials was calculated by using the various molecular models. The more precise results were obtained by Hamieh model based on the effect of the temperature on the surface area of organic molecules. It was proved that the dispersive component of the surface energy of N-MWCNTs-Na-CMC was equal to the geometric mean than that of N-MWCNTs and Na-CMC surfaces. Lewis Acid base properties of the various materials were determined by using the different models and methods. A stronger basic character was highlighted for the different solid surfaces with more accentuated acid base character for N-MWCNT solid. Furthermore, the potential usage of the hybrid nanocomposite was studied for the practical application of the self-powered UV photodetection. On the other hand, the N-MWCNTs-Na-CMC hybrid heterostructure N-MWCNTs-Na-CMC exhibited excellent photoresponse characteristics with a good stability and reproducibility under the UV illumination (λ=382 nm) at zero bias. The high photoresponse performances were mainly attributed to the improved conductivity and enhanced charge transfer resulting from the synergetic effect of N-MWCNTs-Na-CMC hybrid heterostructure. The detailed photoresponse properties of the N-MWCNTs-Na-CMC hybrid heterostructure was discussed in detail using energy band theory.

Structural studies of various olmesartan solvates.

Seven solvates of the angiotensin II receptor blocker agent olmesartan (C24H26N6O3), namely, the methanol (C24H26N6O3·CH4O), ethanol (C24H26N6O3·C2H6O), isopropanol (C24H26N6O3·C3H8O), isobutanol (C24H26N6O3·C4H10O), 2-ethoxyethanol (C24H26N6O3·C4H10O2), chloroform (C24H26N6O3·CHCl3) and acetonitrile (C24H26N6O3·C2H3N) solvates, were successfully obtained. The crystal structures were determined using the single-crystal X-ray diffraction technique and the structural features are described, each solvate containing one molecule of olmesartan and one of solvent in the asymmetric unit. The samples were also analyzed by powder X-ray diffraction. Total lattice energies and binding energies between the olmesartan and solvent molecules were evaluated, which can be partitioned into electrostatic, polarization, dispersion and repulsion components. Hirshfeld and fingerprint plot analysis was performed to highlight the intermolecular contacts. Hydrogen bonding and supramolecular arrangements were comparatively studied for the seven solvates.

Sensitivity tests of cosmic velocity fields to massive neutrinos

ABSTRACT We investigate impacts of massive neutrinos on the cosmic velocity fields, employing high-resolution cosmological N-body simulations provided by the information-optimized CUBE code, where cosmic neutrinos are evolved using collisionless hydrodynamics and their perturbations can be accurately resolved. In this study, we focus, for the first time, on the analysis of massive-neutrino-induced suppression effects in various cosmic velocity field components of velocity magnitude, divergence, vorticity, and dispersion. By varying the neutrino mass sum Mν from 0 to 0.4 eV, the simulations show that the power spectra of vorticity – exclusively sourced by non-linear structure formation that is affected by massive neutrinos significantly – are very sensitive to the mass sum, which potentially provide novel signatures in detecting massive neutrinos. Furthermore, using the χ2 statistic, we quantitatively test the sensitivity of the density and velocity power spectra to the neutrino mass sum. Indeed, we find that the vorticity spectrum has the highest sensitivity, and the null hypothesis of massless neutrinos is incompatible with both vorticity and divergence spectra from Mν = 0.1 eV at high significance (P-value = 0.03 and 0.07, respectively). These results demonstrate clearly the importance of peculiar velocity field measurements, in particular of vorticity and divergence components, in determination of neutrino mass and mass hierarchy.

Deciphering the Reduced Loss in High Fill Factor Inverted Perovskite Solar Cells with Methoxy-Substituted Poly(Triarylamine) as the Hole Selective Contact.

A dopant-free polymeric hole selective contact (HSC) layer is ubiquitous for stable perovskite solar cells (PSCs). However, the intrinsic nonwetting nature of the polymeric HSC impedes the uniform spreading of the perovskite precursor solution, generating a terrible buried interface. Here, we dexterously tackle this dilemma from the perspective of dispersive and polar component surface energies of the HSC layer. A novel triarylamine-based HSC material, poly[bis(4-phenyl)(2,4-dimethoxyphenyl)amine] (2MeO-PTAA), was designed by introducing the polar methoxy groups to the para and ortho positions of the dangling benzene. These nonsymmetrically substituted electron-donating methoxy groups enhanced the polar components of surface energy, allowing more tight interfacial contact between the HSC layer and perovskite and facilitating hole extraction. When utilized as the dopant-free HSC layer in inverted PSCs, the 2MeO-PTAA-based device with CH3NH3PbI3 as the absorber exhibited an encouraging power conversion efficiency of 20.23% and a high fill factor of 84.31% with negligible hysteresis. Finally, a revised detailed balance model was used to verify the drastically lessened surface defect-induced recombination loss and shunt resistance loss in 2MeO-PTAA-based devices. This work demonstrates a facile and efficient way to modulate the buried interface and shed light on the direction to further improve the photovoltaic performance of inverted PSCs with other types of perovskites.

2D Wavelength‐Polarization Dispersive Microspectroscope Based on a Hybrid Plasmonic Helical Nanostructure

AbstractMicrospectrometer features remarkable portability and integration and is prospected to provide quick detection tools to daily life and revolutionize research techniques. Due to the extremely finite footprint, microspectrometer can hardly analyze the polarization feature by placing a polarizer in the optical path as conventional spectrometers. Here, a novel 2D wavelength‐polarization dispersive microspectroscope based on a carbon nanocoil with plasmonic Au nanoparticles (Au/CNC) as a dispersive component is demonstrated. The unique 2D dispersion properties of Au/CNC are examined by microspectroscopic and Fourier spatial microscopic exploration. Au/CNC disperses light as wavelength to bands of different diffraction orders like a grating along the coil axis. The wavelength of the incident light can be obtained from the location of the signal lines in a relatively large visible‐near‐infrared wavelength range. Perpendicular to the coil axis, incident light is dispersed as polarization with bright and dark areas. Therefore, the left‐ and right‐circularly polarized light can be distinguished, and polarization orientation of linearly polarized light can be obtained. This effect provides a powerful microspectrometer that simultaneously analyzes wavelength and polarization features. Moreover, this potent tool can further evolve new revolutionary techniques via integration with other systems.

Structure and Wettability Engineering of Polycrystalline Diamond Films Treated by Thermally Oxidation, Second Growth and Surface Termination

High-quality polycrystalline diamond films with dominated (100)-oriented grains are realized by combining the thermally oxidation and the homogeneous second growth processes. Moreover, we investigate the wettability property of the polycrystalline diamonds in various stages. Different surface structures (with various grain sizes, voids, and orientations, etc.) and terminations (hydrogen or oxygen) have significant effects on the wettability of polycrystalline diamond films. The wettability is further closely related to the polarity of solutions. By measuring the contact angle and calculating the dispersion and polarity components, we estimate the surface energy of polycrystalline diamond films, and explore the factors affecting the surface energy. The modulations in growth quality and wettability property of polycrystalline diamond films provide valuable data for development of diamond-based multiple devices in practical applications.

Experimental and theoretical study of novel amino-functionalized P(V) coordination compounds suggested as inhibitor of MPro of SARS-COV-2 by molecular docking study.

Amino‐functionalized P(V) derivatives providing both N‐ and O‐donor modes have attracted interest owing to their potential to form interesting coordination assemblies with applications such as biological drugs. Novel coordination modes of two‐ and four‐dentate tris (pyridin‐2‐yl)phosphoric triamide OP[NH‐2Py]3 as ([Co(II){[O][NH‐2Py]P(O)[Ph]}2(DMF)2], 1) and ([Cu(II)Cl{[NH‐2Py]2P(O)[N‐2Py]}].DMF, 2) have been synthesized and structurally studied. The metal center environment is distorted octahedral for 1 and distorted square pyramidal for 2. The crystal structure of a new complex of Cu(II) with a Cu[N]4[Cl]2 environment ([Cu(II)Cl2(Pyrazole)4], 3) is also investigated. An evaluation of the inhibitory effect against the coronavirus (Main Protease [MPro] of SARS‐CoV‐2) was carried out by a molecular docking study and illustrates that these compounds have a good interaction tendency with CoV‐2, where 1 has the best binding affinity with the biological target comparable with other SARS‐CoV‐2 drugs. Moreover, theoretical QTAIM and natural bond orbital (NBO) calculations are used to evaluate the metal‐oxygen/‐nitrogen bonds suggesting that they are mainly electrostatic in nature with a slight covalent contribution. A molecular packing analysis using Hirshfeld surface (HS) analysis shows that N—H … O (in 1 and 2) and N—H … Cl (in 3) hydrogen bonds are the dominant interactions that contribute to the crystal packing cohesion. The semi‐empirical PIXEL method indicates that the electrostatic and repulsion energy components in the structures of 1 and 2 and the dispersion and electrostatic components in that of 3 are the major contributors to the total lattice energy.

Development of a lunar soil simulator for Earth-based experiments

A simulator of lunar soil and lunar dust has been developed, designed for modeling various engineering processes in terrestrial conditions. The elemental and granulometric compositions of the simulator were studied using X-ray fluorescence analysis, scanning electron microscopy and laser light scattering. The resulting material will be used in the future to simulate thermophysical processes when creating lunar power generating plants. The finely dispersed component of the simulator based on basalt wool will be used to study the filtration of lunar dust.

Effect of dry abrasion treatments on composite surface quality and bonded joints shear strength

In order to enhance the adhesion properties of composites for further use in structural bonding applications, the effect of different surface treatments on flax/epoxy composite surface topography, surface arithmetic mean height (Sa), surface free energy ( γ s ) and composite to composite bonded joints shear strength (τ) was studied in this research. The main goal of this work was to evaluate the efficiency of abrasion surface treatments, such as sandblasting and sanding in enhancing composites’ adhesion quality compared to traditional mechanical surface treatments such as peel ply. Surface topography was evaluated using an optical microscope. Surface arithmetic mean height (Sa) was estimated via a mechanical surfscan. Surface free energy ( γ s ) was determined using the contact angle method along with the two-component Owens-Wendt model. Composite bonded joints shear strength was evaluated using the single lap shear joint test (SLJ). Trials revealed that specimens treated with sandblasting presented the highest composite bonded joints shear strength (τ). These specimens were characterized by a non-homogeneous surface topography, the highest surface arithmetic mean height (Sa) along with the highest surface free energy ( γ s ) and surface free energy dispersive component ( γ s d ).Unlike peel ply, sandblasting and sanding caused fiber exposure at the surface level. Sand granulometry used for sandblasting had an effect on the composite surface quality and its bonded joints shear strength. Linear regression revealed that composite bonded joints shear strength increases with the increase of the surface free energy dispersive component ( γ s d ). Abrasion treatments such as sandblasting significantly enhanced the adhesion properties of the composite compared to peel ply. Yet it did cause some side effects such as flax fiber damage and sand residue. These side effects could be reduced by opting for less harsh abrasive sand and more sophisticated cleaning processes.

Predictability of Indian Ocean Dipole Over 138 Years Using a CESM Ensemble‐Prediction System

AbstractIn this study, we performed a long‐term ensemble hindcast from 1880 to 2017 (138 years) using the Community Earth System Model (CESM) and conducted a comprehensive investigation of the Indian Ocean Dipole (IOD) predictability. We found that the CESM can produce the IOD prediction skill comparable to that produced by some of the best state‐of‐the‐art coupled general circulation models, achieving a correlation skill of 0.5 for a lead time of one season over the 138 years. The Brier skill score shows one season of the effective probability prediction skill for the below‐ and above‐normal events and no probability prediction skill for the near‐normal events. The potential predictability of the IOD is much higher than the actual prediction skill; for example, the information‐based potential correlation is as high as 0.8 at a 6‐month lead time, suggesting a large scope for improvement in current IOD predictions. Compared with the dispersion component, the signal component dominates the variation in the relative entropy and the relationship between the potential predictability and deterministic prediction skill. An analysis of the IOD prediction skills suggests that the strength of IOD events plays an important role in the IOD prediction skills, regardless of the measurement metrics used to evaluate the prediction skills. Our study also suggested that the remote forcing from the tropical Pacific and the local sea‐air interaction in the tropical Indian Ocean would be two major sources of IOD predictability.

Weakly nonlinear theory for dispersive waves generated by moving seabed deformation

We present a weakly nonlinear theory for the evolution of dispersive transient waves generated by moving seabed deformation. Using a perturbation expansion up to second order, we show that higher-order components affect mostly the leading wave and the region close to the deforming seabed. In particular, the leading wave in the nonlinear regime has higher crests and deeper troughs than the known linear solution, while the trough that propagates together with the moving seabed exhibits pulsating behaviour and has larger depth. We also validate the analytical model with experimental data and obtain good agreement between both approaches. Our results suggest a need to extend existing models that neglect the effects of wave dispersion and higher-order components, especially in view of practical applications in engineering and oceanography.

The Bifurcated σ-Hole···σ-Hole Stacking Interactions.

The bifurcated σ-hole···σ-hole stacking interactions between organosulfur molecules, which are key components of organic optical and electronic materials, were investigated by using a combined method of the Cambridge Structural Database search and quantum chemical calculation. Due to the geometric constraints, the binding energy of one bifurcated σ-hole···σ-hole stacking interaction is in general smaller than the sum of the binding energies of two free monofurcated σ-hole···σ-hole stacking interactions. The bifurcated σ-hole···σ-hole stacking interactions are still of the dispersion-dominated noncovalent interactions. However, in contrast to the linear monofurcated σ-hole···σ-hole stacking interaction, the contribution of the electrostatic energy to the total attractive interaction energy increases significantly and the dispersion component of the total attractive interaction energy decreases significantly for the bifurcated σ-hole···σ-hole stacking interaction. Another important finding of this study is that the low-cost spin-component scaled zeroth-order symmetry-adapted perturbation theory performs perfectly in the study of the bifurcated σ-hole···σ-hole stacking interactions. This work will provide valuable information for the design and synthesis of novel organic optical and electronic materials.

Liquid partial surface tensions obtained by an adapted Good-Girifalco approach from interfacial tensions and DiPEVa solubility parameters

This publication highlights the achievement of partial surface tension properties of liquids using an adapted Good-Girifalco approach from interfacial tensions and DiPEVa solubility parameters. The proposed method is simple to apply, and different databases of interfacial tension of water and one of squalene were compared. The water interfacial tension data was appropriate for estimating the dispersive component of the surface tension. In contrast, the squalene interfacial tension is more accurate for calculating the polar component of surface tension because of the miscibility behavior of the liquids. The approach strengthens the relationship between solubility parameters and the surface tension parameter. Due to the enormous importance of 3DSP, especially HSP, for the current technological field, the extension of its physicochemical background to the surface tension parameter is of paramount importance for the area of ​​Materials Science. Thus, the data presented here are especially relevant for applications dependent on surface and interfacial phenomena or dielectric constant related to 3DSP.

Kinematic properties of white dwarfs

Context. Kinematic and chemical tagging of stellar populations have both revealed much information on the past and recent history of the Milky Way, including its formation history, merger events, and mixing of populations across the Galactic disk and halo. Aims. We present the first detailed 3D kinematic analysis of a sample of 3133 white dwarfs that used Gaia astrometry plus radial velocities, which were measured either by Gaia or by ground-based spectroscopic observations. The sample includes either isolated white dwarfs that have direct radial velocity measurements, or white dwarfs that belong to common proper motion pairs that contain nondegenerate companions with available radial velocities. A subset of common proper motion pairs also have metal abundances that have been measured by large-scale spectroscopic surveys or by our own follow-up observations. Methods. We used the white dwarfs as astrophysical clocks by determining their masses and total ages through interpolation with dedicated evolutionary models. We also used the nondegenerate companions in common proper motions to chemically tag the population. Combining accurate radial velocities with Gaia astrometry and proper motions, we derived the velocity components of our sample in the Galactic rest frame and their Galactic orbital parameters. Results. The sample is mostly located within ∼300 pc from the Sun. It predominantly contains (90–95%) thin-disk stars with almost circular Galactic orbits, while the remaining 5–10% of stars have more eccentric trajectories and belong to the thick disk. We identified seven isolated white dwarfs and two common proper motion pairs as halo members. We determined the age – velocity dispersion relation for the thin-disk members, which agrees with previous results that were achieved from different white dwarf samples without published radial velocities. The age – velocity dispersion relation shows signatures of dynamical heating and saturation after 4–6 Gyr. We observed a mild anticorrelation between [Fe/H] and the radial component of the average velocity dispersion, showing that dynamical mixing of populations takes place in the Galactic disk, as was detected through the analysis of other samples of FGK stars. Conclusions. We have shown that a white dwarf sample with accurate 3D kinematics and well-measured chemical compositions enables a wider understanding of their population in the solar neighborhood and its connection with the Galactic chemodynamics. The legacy of existing spectroscopic surveys will be boosted by the availability of upcoming larger samples of white dwarfs and common proper motion pairs with more uniform high-quality data.

Surface thermodynamics and Lewis acid-base properties of metal-organic framework Crystals by Inverse gas chromatography at infinite dilution

In this study, the surface thermodynamic properties and more particularly, the dispersive component γsd of the surface energy of crystals of a Zr-based MOF, UiO-66 (Zr6O4(OH)4(BDC)6; BDC = benzene 1,4-dicarboxylic acid), the specific interactions, and their acid-base constants were determined by using different molecular models and inverse gas chromatography methods. The determination of γsd of the UiO-66 surface was obtained by using several models such as Dorris-Gray and those based on the Fowkes relation by applying the various molecular models giving the surface areas of n-alkanes and polar organic molecules. Six models were used: Kiselev, spherical, geometric, Van der Waals, Redlich-Kwong, and cylindrical models. The obtained results were corrected by using our model taking into account the thermal effect on the surface areas of molecules. A linear equation was obtained between γsd and the temperature.The specific free energy, enthalpy and entropy of adsorption of polar molecules, as well as the acid and base constants of UiO-66 particles were determined with an excellent precision.It was also proved that the UiO-66 surface exhibited an amphoteric acid-base character with stronger acidity. The linear variations of the specific free energy of interaction as a function of the temperature allowed to obtain the specific surface enthalpy and entropy of adsorption, as well as the acid and base constants of UiO-66 by using ten different models and methods. The best results were obtained by using our model that gave the more precise values of the acid constant KA=0.57, the base constant KD=0.18 of the MOF particles and the ratio KA/KD = 3.14 clearly proving a strong acid character of the UiO-66 surface.