جستجوی مقالات مرتبط با کلیدواژه « thermodynamic parameters » در نشریات گروه « پزشکی »

Clotrimazole is a broad-spectrum antifungal drug within the imidazole group that can potentially disrupt fungal cell ergosterol synthesis. It is a lipophilic molecule with a slow dissolution rate in water and poor aqueous solubility. Many efforts have been made in the literature to enhance clotrimazole’s solubility. Herein, with the aim of solubility enhancement, the solubility profile of clotrimazole in the aqueous binary mixtures of N-methyl-2-pyrrolidone at temperatures ranging from 293.2 to 313.2 K was investigated. The experimental solubility values were enhanced by increasing cosolvent composition and temperature. Furthermore, four mathematical cosolvency models were applied to correlate the solid-liquid equilibrium data, and the model accuracy results were shown as the mean relative deviation. Additionally, density values of saturated clotrimazole solution in the studied binary system were determined and reported. Gibbs and van’t Hoff equations were also employed to compute dissolution thermodynamic parameters at Thm=303 K.

Biosorption ability of commercial dried Saccharomyces cerevisiae (Baker’s yeast), to remove the Methyl green dye from water, was studied. This dye was chosen due to wide using of it in the different industries which is dumped into wastewater. With a view to explore the optimum conditions for adsorption of dye, Batch experiments were performed under various experimental affecting conditions, which are dye concentration, temperature, contact time. The experiment's batches were held using various initial concentrations of dye from 10 to 50 mg L-1, absorbent (Baker's yeast) dosage 0.075g at diverse temperatures (20, 30 and 40°C), and pH=7. In which the results have shown when the temperature increased the adsorption efficiency increased too. The removal percentage (%R) of dye by the baker’s yeast reached equilibrium after 80 minutes. As well as, adsorption isotherm models (Freundlich and Langmuir) were studied. The maximum biosorption capacity values were calculated at mentioned conditions. Furthermore, Kinetic and Thermodynamic parameters were calculated for this adsorption process, which are indicating the process is endothermic, spontaneous process in nature and follow pseudo 2. Order model.

Ascorbyl palmitate (AP) is an example of natural secondary food antioxidant, which has been used for oxidative rancidity prevention in food industry. In this study, the interaction of AP with bovine serum albumin (BSA) was investigated.
The mechanism of BSA interaction with AP was investigated using spectroscopic methods (UV-Vis, fluorescence). The thermodynamic parameters including enthalpy change (ΔH), entropy change (ΔS), and Gibb’s free energy (ΔG) were calculated using Van’t Hoff equation at different temperatures.
The experimental results showed that UV-Vis absorption spectra of BSA decreased upon increasing AP concentration, indicating that the AP can bind to BSA. Formation of the AP-BSA complex was approved by quenching of fluorescence and the quenching mechanism was found to be resultant from dynamic procedure. The positive values of both ΔH and ΔS showed that hydrophobic forces were the major binding forces. The negative value of ΔG demonstrated that AP interacts with BSA spontaneously. Molecular docking results confirmed that AP binds to BSA through hydrophobic forces.
The attained results showed that AP can bind to BSA and effectively distributed into the bloodstream.

Lipases are valuable biocatalysts which are widely used in the detergent, food, dairy and pharmaceutical industries. The aims of the present study included the isolation of a lipase-producer from industrial zones and the partial characterization of the enzyme. A number of bacteria were isolated from sites related to the oil industries. An isolate forming a halo zone in a selective medium (TW agar) was then selected and grown on a medium suitable for the production of lipase. The isolate was subsequently identified by the 16S rRNA sequencing method, and its enzyme activity was measured by a spectrophotometer using pNPP as a substrate. The selected isolate was identified by the molecular method as Pseudomonas sp. Its extracellular lipase activity was 41.5 ± 1.4 U/ml, and the high affinity of this enzyme for the substrate was indicated by the kinetic parameters of Km and Vm, which were estimated by the the Lineweaver-Burk plot as 0.77 mM and 49.5 U/ml, respectively. Activation energy of lipase calculated from the Arrhenius plot was found to be 20.78 kJ/mol, and a temperature coefficient (Q10) of 4.39 indicated the high catalytic activity of the enzyme and the temperature dependence of the enzymatic reaction. The results demonstrated that the indigenous isolate could have potential applications in many relevant industries.

Batch adsorption experiments using activated carbon prepared from Morringa Indica bark were conducted to remove fluoride from aqueous solution. A minimum contact time of 25 min was required for optimum fluoride removal. The influence of adsorbent, dose, pH, co-ions (cations and anions) on fluoride removal by the activated carbon has been experimentally verified. The adsorption of fluoride was studied at 30 C, 40 C and 50 C. The kinetics of adsorption and adsorption isotherms at different temperatures were studied. The fluoride adsorption obeyed both Langmuir and Freundlich isotherms and followed a pseudo first order kinetic model. The thermodynamic studies revealed that the fluoride adsorption by Morringa Indica is an endothermic process indicating an increase in sorption rate at higher temperatures. The negative values of G indicate the spontaneity of adsorption. SEM and XRD studies confirmed the surface morphological characteristics of the adsorbent and the deposition of fluoride on the surface of the material.