Standard Entropy Research Articles

An Empirical Study on Vagueness Detection in Privacy Policy Texts

Website privacy policies outline how a website handles personal information. Many such policies are written vaguely, making it difficult for users to comprehend what data is collected and how it’s used, posing a threat to privacy and security. The empirical study in this paper aims to address this issue by applying transformer models to automatically detect the level of vagueness in privacy policy texts. We calculate the vagueness scores based on annotations obtained through arithmetic mean, geometric mean, and harmonic mean of the individual annotations and discretize the policy text into four distinct vagueness categories. Our detailed numerical study shows that transformer models perform well for the vagueness classification tasks and they can be effective in enhancing the clarity and transparency of privacy policies. Our experiments also highlight the importance of reliable annotations and show that the transformer model performance can be enhanced with more reliable annotations with lower standard deviation and entropy values.

Investigation of the removal kinetics, thermodynamics and adsorption mechanism of anionic textile dye, Remazol Red RB, with powder pumice, a sustainable adsorbent from waste water.

Excessive growth and abnormal use of dyes and water in the textile industry cause serious environmental problems, especially with excessive pollution of water bodies. Adsorption is an attractive, feasible, low-cost, highly efficient and sustainable technique in terms of green chemistry for the removal of pollutants from water. This study aims to investigate the removal kinetics, thermodynamics and adsorption mechanism of Remazol Red RB, which was chosen as a representative anionic reactive dye, from synthetic wastewater using powdered pumice, taking into account various experimental parameters such as initial dye concentration, adsorption time, temperature and pH. Moreover, to support the proposed adsorption mechanism, before and after adsorption of the samples, the Fourier transform infrared spectrophotometer (FTIR) spectra, X-ray powder diffraction (XRD) diffractograms and High resolution transmission electron microscopy (HRTEM) images were also taken and used. The results show that powder pumice can be an efficient adsorbent for anionic dye removal with a relatively high adsorption capacity of 38.90mg/g, and it is very effective in 30-60min in mild conditions. The experimental data showed a high agreement with the pseudo-second-order kinetic model and the Freundlich adsorption isotherm equation. In addition, thermodynamically, the process exhibited exothermic nature and standard isosteric enthalpy and entropy changes of -4.93kJ/mol and 16.11J/mol. K were calculated. It was determined that the adsorption mechanism was predominantly based on T-shaped pi-pi interactions and had physical characteristics.

On Solving Parametric Optimization Problem of an End Milling Process for Machining of Al 1070 using MCDM Techniques: A Comparative Analysis

ABSTRACT Determining the optimal intermix of various input parameters for an end milling process is an important task to explore its fullest performance along with the achievement of the desired responses. Several multi-criteria decision-making techniques, like technique for order preference by similarity to ideal solution (TOPSIS), grey relational analysis and multiobjective optimisation on the basis of ratio analysis (MOORA), have been applied for solving parametric optimisation problems of milling processes while assigning equal importance to the considered responses. In this paper, the optimal combinations of cutting speed, feed rate and depth of cut of an end milling process during the machining of Al 1070 alloy are determined using the weighted sum model (WSM), weighted product model (WPM), weighted aggregated sum product assessment (WASPAS), MOORA, TOPSIS, evaluation based on distance from average solution (EDAS), additive ratio assessment (ARAS) and complex proportional assessment (COPRAS) methods with the allocation of unequal weights to the responses determined by standard deviation and entropy techniques. The derived solutions are also compared when the same importance is assigned to the responses. From the results, a parametric combination of 255 rpm cutting speed, 82 mm/min feed rate and 0.75 depth of cut is identified by WSM, WPM, WASPAS, COPRAS, TOPSIS and ARAS methods to achieve the optimal values of material removal rate (MRR) and average surface roughness (Ra) as 595.23 mm3/min and 13.79 µm, respectively. It is also noticed that both feed rate and depth of cut significantly influence MRR and Ra during the machining of Al 1070 alloy.

Development and characterization of a clay-HDTMABr composite for the removal of Cr(VI) from aqueous solutions with special emphasis on the electrochemical interface

This research aims to study the removal of chromium in its toxic form, Cr (VI), from wastewater, using clay and modified clay with Hexadecyltrimethyl ammonium bromide (HDTMABr)as adsorbents. The modified clay is obtained by impregnating a known quantity of HDTMABr into the clay. The two materials were characterized by different techniques, such as X-ray diffraction, which is used to determine the inorganic composition and the phyllite structures it contains. Thermal analysis TGA isused to understand the thermal behavior as function of the sintering temperature. Nitrogen adsorption/desorption is used to get the pores' size and surface area, using the Brunauer-Emmett-Teller (BET) theory. Scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDAX) is used to study the surface morphology of the bare clay and the HDTMABr/clay. The operating conditions, such as contact times, pH, and adsorption temperatures, were studied, and optimized to improve the efficiency of the adsorption process. The adsorption is favored in acidic medium and room temperature, giving adsorption capacities for Cr(VI) of 12 mg/g and 250 mg/g for the clay and clay/HDTMABr, respectively. The reaction kinetics were studied and found to fit a pseudo-second-order model. The standard entropy (ΔS°), enthalpy (ΔH°), and Gibbs free energy (ΔG°) changes indicate that the chromium (VI) adsorption process is a physical, spontaneous, endothermic process. Cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS) are used for the electrochemical characterization of the raw clay and clay/HDTMABr in [Fe(CN)6]3-/4-/ 0.1 M KCl solution. The linear scan anodic stripping voltammetry (LSASV) is used for the reduction the Cr(VI) to Cr(III), indicating that Cr(VI) accumulates better at the surface of clay/HDTMABr compared to the bare graphite and the raw clay.

Insight of molecular interactions between short‐chain tetraalkylammonium bromides and cetyltrimethylammonium bromide: A spectroscopic and thermodynamic approach

AbstractThe influence of tetraalkylammonium salts, viz., tetraethylammonium, tetrapropylammonium, and tetrabutylammonium bromides (0.005, 0.010, 0.015 mol kg−1) on the micellar behavior of aqueous solutions of the cationic surfactant cetyltrimethylammonium bromide (CTAB, 0.2–2 mmol kg−1) over the 298.15–313.15 K temperature range has been studied by conductometric method. From conductivity versus surfactant concentration plots, the critical micelle concentration (CMC) of CTAB has been determined, which shows that the tetraalkylammonium bromides promote the formation of CTAB aggregates. Further, from the temperature dependence of CMC values, the degree of ionization, the counterion binding constant along with some thermodynamic parameters of micellization, such as standard free energy change (), standard enthalpy change (), standard entropy change () have been calculated. From the values of , and , it has been concluded that our ternary system is both enthalpy as well as entropy controlled. Similar CMC values were obtained from UV–Visible spectrometry measurements, using pyrene as a probe at ambient temperature. Also 1H‐NMR and FTIR methods give a greater understanding of the molecular scale interactions between the tetraalkylammonium bromides and the cationic surfactant.

Thermodynamic Analysis of In Situ Underground Pyrolysis of Tar-Rich Coal: Primary Reactions.

In situ underground pyrolysis of tar-rich coal is significant for alleviating the scarcity of oil and gas resources and realizing the green and efficient development and utilization of coal in China. Tar-rich coal is often subjected to high axial pressure, surrounding pressure, and pore pressure in the in situ underground pyrolysis environment. Consequently, laboratory simulation conditions are difficult to meet the actual needs. This paper conducts a thermodynamic study of the pyrolysis characteristics of tar-rich coal under an in situ environment. Typical thermodynamic functions of tar-rich coal, including the standard enthalpy of formation, standard formation Gibbs free energy, and standard entropy, were determined. Ten representative primary reactions were constructed with typical tar-rich coal pyrolysis oil components as a guide. The Gibbs free energy and equilibrium constant change laws of the above reactions were analyzed for pyrolysis temperatures from 200 to 800 °C and pyrolysis pressures from atmospheric pressure to 10 MPa. The results showed that the standard enthalpy of formation of tar-rich coal was -72.27 kJ·mol-1, the standard entropy was -37.79 J·mol-1·K-1, and the standard formation Gibbs free energy was -60.01 kJ·mol-1. When the reaction pressure increased from atmospheric pressure to 10 MPa, the thermodynamically feasible initial temperature fractions of the primary reaction of tar-rich coal pyrolysis all showed different degrees of increase. In the underground environment, the initial temperature of the primary reaction of in situ underground pyrolysis of tar-rich coal moves to a higher-temperature gradient to some extent, so the adjustment of the reaction temperature and pressure could guide the directional regulation of the in situ underground pyrolysis products of tar-rich coal.

Electrochemical characterization and performance of phenothiazine derivatives as redox mediators

Two phenothiazine derivatives were synthesized as new redox mediators. Their electrochemical properties were compared with conventional redox mediators, such as thionine, ferricyanide(III), and hexaammineruthenium(III). Cyclic voltammetry experiments were performed under various conditions on glassy carbon and ultramicroelectrodes to investigate the proton-coupled electron transfer reaction mechanism, electrochemical reversibility, and chemical stability of the redox mediators. The number of intervening electrons and protons in the redox processes of redox mediators at each temperature was estimated accordingly. Furthermore, thermodynamic parameters (standard enthalpy change, standard entropy change, and standard Gibbs free energy) of redox mediators could be evaluated by analyzing their electrochemical behavior according to the reaction temperatures. The mediator performance was also analyzed for the oxidation of reduced nicotinamide adenine dinucleotide. These experimental and analytical results confirm that the performance of redox mediators is similar or superior to those of other mediators.

A new thermodynamic description of pure silicon from 0 K at 1 bar

Third-generation Calphad models have been applied to describe the thermodynamic properties of pure crystalline and liquid/amorphous silicon. The extended Planck-Einstein model was used to evaluate the standard entropies at 298.15 K; the values for the amorphous phase were reported for the first time. A new approach was proposed for the evaluation of parameters for the two-state liquid model for pure silicon. In the majority of previous 3rd-generation CALPHAD assessments it was proposed to fix the enthalpy or entropy parameters of the ΔGdif equation, which could result in the inability of the model to describe the thermodynamics of the fusion of the pure elements. The alternative approach is to derive these parameters from the fixed fraction of translational (liquid-like) atoms at the fusion temperature and to compare the results with the heat capacity data. The new model representation of the liquid/amorphous phase allows us to obtain a better description of the experimental data for the isobaric heat capacity of the liquid phase.

Synthesis of nanostructured novel ion-imprinted polymer for selective removal of Cu2+ and Sr2+ ions from reverse osmosis concentrated brine

This study aims to prepare an ion-imprinted polymer (IIP) using copper sulfate as a template and potassium persulfate as an initiator to selectively adsorb copper ions (Cu2+) from aqueous solutions and in an attempt to also test its applicability for removing strontium ions (Sr2+). The prepared polymer was denoted by IIP-Cu. Various physical and chemical characterizations were performed for the prepared IIP-Cu. The scanning electron microscopy and transmission electron microscopy analyses confirmed the cavities formed after the removal of the template. It also indicated that the IIP-Cu had a rough and porous topology. The X-ray photoelectron spectroscopy confirmed the successful removal of the Cu template from IIP-Cu. The Brunauer-Emmet-Teller revealed that the surface area of IIP-Cu is as high as 152.3 m2/g while the pore radius is 8.51 nm. The effect of pH indicated that the maximum adsorption of Cu2+ was achieved at pH 8 with 98.7%. Isotherm studies revealed that the adsorption of Cu2+ was best explained using Langmuir models with a maximum adsorption capacity of 159 mg/g. The effect of temperature revealed that an increase in temperature had an adverse impact on Cu2+ removal from the aqueous solution, which was further confirmed by thermodynamic studies. The negative value of standard enthalpy change (−4.641 kJ/mol) revealed that the adsorption of Cu2+ onto IIP-Cu was exothermic. While the continuous increase in Gibbs free energy from −6776 kJ/mol to −8385 kJ/mol with the increase in temperature indicated that the adsorption process was spontaneous and feasible. Lastly, the positive value of the standard entropy change (0.023 J/mol.K) suggested that the Cu2+ adsorption onto IIP-Cu had a good affinity at the solid-liquid surface. The efficiency of the prepared IIP-Cu was also tested by studying the adsorption capacity using Sr2+ and real brine water. The results revealed that IIP-Cu was able to remove 63.57% of Sr2+ at pH 8. While the adsorption studies revealed that the experiment was best described using the Langmuir model with a maximum adsorption capacity of 76.92 mg/g. Additionally, IIP-Cu was applied in a real brine sample, which consisted of various metal ions. The highest percentage of Cu2+ removal was 90.6% and the lowest was 65.63% in 1:4 and 1:1 brine ratios, respectively. However, this study indicates the successful application of IIP-Cu in a real sample when it comes to the effective and efficient removal of Cu2+ in a solution consisting of various competing ions.

Microbiological and spectrophotometric methods for the determination of tioconazole: A comparative thermodynamic study

Two sensitive microbiological and charge transfer spectrophotometric methods have been developed for the quantitative determination of the antifungal drug, tioconazole, in its pure form and pharmaceutical preparations. The microbiological assay was based on the agar disk diffusion method by measuring the diameter of the inhibition zones related to different concentrations of tioconazole. The spectrophotometric method relied on charge transfer complex formation between tioconazole as an n-donor and chloranilic acid as a π-acceptor at room temperature. The formed complex was measured at λmax = 530 nm. The molar absorptivity and the formation constant of the formed complex were determined using different models, including the Benesi-Hildebrand, Foster-Hammick-Wardley, Scott, Pushkin-Varshney-Kamoonpuri, and Scatchard equations. Different thermodynamic parameters associated with the complex formation, including the free energy change (ΔG°), the standard enthalpy (ΔH°), and the standard entropy change (ΔS°), were evaluated. The two methods were validated in conformity with ICH-recommended guidelines and employed successfully for the quantification of tioconazole in both pure form and pharmaceutical formulations.

Impacts of several salts on the clouding development, nature of interactions and associated physico-chemical variables of mixture of promethazine hydrochloride and conventional nonionic surfactant

Herein, in the presence of electrolytes, the cloud points (CPs) of the mixture of a conventional uncharged amphiphile (triton X-100 (TX-100)) and promethazine hydrochloride (PMH; phenothiazine medicine) were measured and explained in great details. The CP values of the employed surfactant + PMH system were reduced with enhancing salts contents (NaCl, Na2SO4, NH4Cl, and (NH4)2SO4)), while the CP values of the study system followed the trend: Na2SO4 < NaCl and (NH4)2SO4 < NH4Cl. The different thermodynamic parameters of phase separation, including standard free energy (ΔG 0 c), enthalpy (ΔH 0 c), and entropy (ΔS 0 c) changes were also calculated and discussed elaborately. The values of free energy change (ΔG 0 c) were obtained to be positive, indicating that the clouding phenomena are non-spontaneous. Different transfer properties (free energy (ΔG 0 c.t), enthalpy (ΔH 0 c,t ), and entropy (ΔS 0 c,t ) of transfer), intrinsic enthalpy gain (ΔH 0,*c) and compensation temperature (T c) of the inspected system have also been assessed and discussed.

Thermodynamic Properties of Sm3Cl7 Chloride in the Standard State at 298.15 K

The EMF in the 473–728 K range of temperatures is measured for solid-phase galvanic cells (‒) Sm|SmCl2||BaCl2||SmCl3|Sm3Cl7 (+), (–) Sm|SmCl2||BaCl2||Sm3Cl7|SmCl2 (+), (–) SmCl2|Sm3Cl7|| BaCl2||SmCl3|Sm3Cl7 (+), and (–) Mg|MgCl2||BaCl2||SmCl3|Sm3Cl7 (+). Experimental data are processed according to the second law of thermodynamics using literature values of thermodynamic characteristics of the components of the EMF-forming reaction: Sm, Mg, SmCl2, SmCl3, and MgCl2. Values of the standard Gibbs energy of formation, the standard enthalpy of formation, and the standard entropy of chloride Sm3Cl7 at a temperature of 298.15 K are obtained by averaging data on four galvanic cells.

Thermodynamic Parameters of Berberine with Kolliphor Mixtures Adsorption and Micellization.

The poor solubility of berberine (Ber) in water limits its practical use. Its solubility can be increased, among other ways, by the addition of surfactants. Of the surfactants, Kolliphor® ELP (ELP) and Kolliphor® RH 40 (RH40) can be very useful in this respect. The increase of Ber's solubility in water in the presence of ELP and RH40 should be reflected in the composition of the surface layers at the water-air interface and the micelles. The determined composition is reflected in the Gibbs energy of interactions of berberine with ELP and RH40 through the water phase and the standard Gibbs free energy, enthalpy, and entropy of adsorption and micellization. These energies were determined from the equations proposed by us, based on the Gibbs surface excess concentration of the Ber mixture with ELP and RH40, the activity of these compounds in the surface layer at the water-air interface and in the micelles obtained by the Hua and Rosen method, and the contributions of Ber, ELP, and RH40 to the reduction in the water surface tension. For this determination, the measurements of the surface tension of the aqueous solution of the Ber mixture with ELP or RH40 and that of the Ber mixture with these two surfactants, as well as the density and conductivity were performed. Moreover, the fluorescence emission spectra for the Ber + surfactant mixtures were recorded.

Bayesian improved cross entropy method for network reliability assessment

We identify the zero count problem (or overfitting) of cross-entropy-based methods in the context of network reliability assessment, and propose a consistent Bayesian estimator that mitigates this issue. Thereby, we derive the posterior predictive distribution of importance sampling distribution parameters that replaces the weighted maximum likelihood estimation employed in the standard cross entropy optimization. For rare event estimation, we embed the Bayesian estimator into the improved cross entropy (iCE) method and provide theoretical insights into the adaptive selection of intermediate target distributions in the iCE. The modified version of the iCE, termed the Bayesian iCE (BiCE), is proved to be unbiased. By contrast, even with higher computational cost, the standard iCE method is often significantly biased when solving network reliability problems. Our numerical investigations indicate that a uniform prior in the proposed BiCE method performs suboptimally, and an informative symmetric Dirichlet prior is suggested.

THERMODYNAMIC PROPERTIES OF THE Cu2GeSe3 COMPOUND

The Cu2GeSe3 compound and phases based on it are of interest as environmentally friendly thermoelectric and photovoltaic materials. This paper presents the results of a thermodynamic study of this compound by the method of electromotive forces. We measured the EMF of concentration cells concerning copper electrode with solid Cu+ conductive electrolyte Cu4RbCl3I2 in the 300-450 K temperature range. Based on the obtained experimental data, the partial molar functions of copper in equilibrium alloys from the three-phase region of the Cu2GeSe3 -GeSe2-Se phase diagram, as well as the standard thermodynamic functions of formation and the standard entropy of the Cu2GeSe3 compound, are calculated. A comparative analysis of the obtained results with the available literature data was carried out

Kinetics and Mechanism of In(III) Ions Electroreduction on Cyclically Renewable Liquid Silver Amalgam Film Electrode: Significance of the Active Complexes of In(III)—Acetazolamide

The results of kinetic measurements revealed an accelerating effect of acetazolamide (ACT) on the multistep In(III) ions electroreduction in chlorates(VII) on a novel, cyclically renewable liquid silver amalgam film electrode (R-AgLAFE). The kinetic and thermodynamic parameters were determined by applying the DC polarography, square-wave (SWV) and cyclic voltammetry (CV), as well as electrochemical impedance spectroscopy (EIS). It was shown that ACT catalyzed the electrode reaction ("cap-pair" effect) by adsorbing on the surface of the R-AgLAFE electrode. The catalytic activity of ACT was explained as related to its ability to form active In(III)- acetazolamide complexes on the electrode surface, facilitating the electron transfer process. The active complexes constitute a substrate in the electroreduction process and their different structures and properties are responsible for differences in the catalytic activity. The determined values of the activation energy ΔH≠ point to the catalytic activity of ACT in the In(III) ions electroreduction process in chlorates(VII). Analysis of the standard entropy values ΔS0 confirm changes in the dynamics of the electrode process.

Group additivity values for entropy and heat capacities of C2–C8 alkanes, alkyl hydroperoxides, and their radicals

Group additivity values for the thermodynamic properties of oxygenated radicals are poorly determined due to the absence of high quality reference data. Here, a set of 58 group additive values (GAV) for the standard entropy and heat capacity of relevance to alkane oxidation is derived from fits to an extensive and accurate database of standard entropies (298.15 K) and heat capacities (300–3000 K) recently calculated with the “STAR-1D” formalism. The 192 species in this database represent the alkanes (RH), alkyl radicals (Ṙ), alkyl hydroperoxides (RO2H), alkyl-peroxy (RȮ2) and hydroperoxy-alkyl (Q˙OOH) radicals for all of the isomers of C2–C5 alkane fuels and a select number of isomers of C6–C9 species. The STAR-1D thermochemical data for this set of species was previously obtained from a coupling of scaled B2PLYPD3/cc-pVTZ vibrational analyses with scaled ωB97X-D/cc-pVTZ one-dimensional hindered rotor corrections. The 2σ uncertainties in the GAV results relative to the STAR-1D data set are 2.4 cal K–1 mol–1 for the entropies and at most 2.0 cal K–1 mol–1 for the heat capacities in the temperature range 500–800 K. The 2σ fitting uncertainties in the heat capacity gradually reduce at higher temperatures reaching a value of 0.8 cal K–1 mol–1 at 2000 K decreasing to only 0.5 cal K–1 mol–1 at 3000 K. The high degree of accuracy for the GAV representations is obtained through the introduction of various new group terms, together with the re-optimization of existing group terms. Among the full set of 58 GAV terms, 25 include non-next-nearest neighbor interactions (NNI) and β-corrections. The updated GAVs can be applied in the prediction of entropies and heat capacities for a wide range of hydrocarbons and hydroperoxide species and their radicals, which is important to the accurate prediction of fuel reactivity at low-temperatures in the range 600–1000 K.

Selective adsorption of gadolinium from real leachate using a natural bentonite clay

This article investigated the recovery of Gd3+ from real leachate of phosphogypsum (PG) using natural bentonite clay. Firstly, a detailed adsorption study was performed using synthetic Gd3+ solutions. Then, it was investigated the clay performance in the real PG leachate. The characterization results indicate classical bentonite characteristics, such as rugosity and an SBET 91.3 m² g−1, with meso (Dp =3.82 nm) and macroporous (Dp =52.6 nm). In addition, it was identified that the major functional groups are hydroxyl and silicate, with the presence of organic matter. The initial pH solution effect indicates that the optimum removal of Gd3+ is at pH (6), attributing to the pHpzc being at 5.75 and the negatively charged surface above the pHpzc. The Avrami fractional order model was the most suitable for describing the experimental kinetic data. The Langmuir was the proper model for describing the adsorption isotherms, indicating that the Gd3+ forms a monolayer at the surface of the bentonite. The maximum adsorption capacity at pH 6.0 was 121.5 mg g−1. The thermodynamic parameters indicate that the adsorption is spontaneous, with a standard enthalpy change of − 92.30 kJ mol−1, indicating an ionic exchange, where the Gd3+ tends to be organized at the surface, according to the standard entropy change of − 206.0 J K−1 mol−1. The fixed bed adsorption test showed that Gd3+ could be adsorbed for up to 200 min without regeneration. Regeneration results show that the citric acid is more efficient in desorbing the Gd3+ from the bentonite, reaching up to 8 cycles without efficiency loss. Finally, the bentonite clay could selectively recover Gd3+ from the real PG leachate.

Physicochemical insights into the micellar delivery of doxycycline and minocycline to the carrier protein in aqueous environment

Physicochemical understanding of the micellar drug delivery is essential for designing efficient drug carrier molecules. An in-depth analysis of the partitioning mechanism of drugs in a quantitative manner and the effects of partitioning on the delivery of drugs through micellar media is a subject of enormous research. This paper focuses on the quantitative measurements of the binding of two antibiotic drugs from tetracycline family, doxycycline and minocycline with the carrier protein human serum albumin (HSA). The partitioning of both the drugs in the micellar system of hexadecyltrimethylammonium bromide (HTAB) and their delivery to HSA through this micellar system was also studied applying spectroscopy and calorimetry. A combination of fluorescence spectroscopy, isothermal titration calorimetry (ITC) and docking studies suggest that both the drugs bind close to Site I of HSA. The ITC results establish that the association of drugs with the protein occurs with an affinity of 103-104 M−1 and the binding is mainly entropy driven. The partitioning mechanisms have been evaluated in terms of the values of the changes in values of standard molar Gibbs free-energy, enthalpy, entropy, and partitioning stoichiometry. The thermodynamic signatures associated with the drug-HSA binding in the presence of HTAB micelles suggest that the partitioning of doxycycline/minocycline in the micelles of HTAB changes their interaction behavior with HSA. These findings provide deep understanding about the micellar drug delivery systems, thereby suggesting their potential applications in strategies for more effective therapeutics.

Interaction between oxidised state of quercetin and bovine serum albumin in presence of surfactant aggregates with different charges

The present investigation focuses on the role of surfactant and its charge on the interaction of flavonoid Quercetin (QCT) and Bovine serum albumin (BSA). QCT is known to undergo autoxidation in many chemical environments which has different characteristics compared to its non-oxidised structure. In this experiment, two ionic surfactants used. They are anionic surfactant, Sodium dodecyl sulfate (SDS) and Cationic surfactants Cetyl pyridinium bromide (CPB). The characterizations employed are conductivity, FT-IR, UV–visible spectroscopy, Dynamic light scattering (DLS) and Zeta potential measurements. The critical micellar concentration (CMC) as well as the counter-ion binding constant (β) have been calculated by making use of specific conductance values, in aqueous medium at 300 K. Various thermodynamic parameters, ΔG0 m, standard free energy of micellization, ΔH0 m, standard enthalpy of micellization and ΔS0 m, standard entropy of micellization are calculated. The negative value of ΔG0 m in all systems is indicative of spontaneous binding occurring in both QCT + BSA + SDS (−23.35 kJ mol−1) and QCT + BSA + CPB (−27.18 kJ mol−1). The higher negative value infers the latter is a more stable system with greater spontaneity. The UV-visible spectroscopy study points at stronger binding of QCT and BSA in presence of surfactants and also there is stronger binding of CPB in ternary mixture with higher binding constant compared to SDS ternary mixture. Which is evident from the binding constant calculated from Benesi-Hildebrand plot (QCT + BSA + SDS, 244.46 M−1; QCT + BSA + CPB, 336.53 M−1). Further, the structural alterations occurring in the above systems has been observed by FT-IR spectroscopy. The DLS and Zeta potential measurements also support the above finding. Communicated by Ramaswamy H. Sarma