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This study investigates the dynamic response of an infinite structure comprising two coaxial cylinders employing the one-relaxation-time generalized thermoelastic diffusion model. The inner cylinder, serving as a cavity, possessing a radius a, while the outer cylinder has radius b. The inner cylinder is insulated and experiencing a localized thermal load with thickness 2 h. The outer cylinder, with radius b, is also experiencing to a localized thermal load with width 2 h, and its surface exhibits no traction. Additionally, the structure experiences the influence of a solenoidal body force. The analysis of this problem employs a combination of Laplace transform, inverse Laplace transform, and exponential Fourier transform techniques. Numerical analysis of the resulting solutions reveals the variations in temperature, displacement, radial stress, concentration, and potential fields as a function of the radial coordinate. Results indicate a minimal impact of the time interval on the temperature distribution, while displacement and radial stress exhibit significant time-dependent behavior. These findings highlight the significance of incorporating thermoelastic diffusion theory in the analysis of real-world engineering problems. [ABSTRACT FROM AUTHOR]

The study of thermal therapy to tumors and the response of living cells to this therapy used to treat tumor is very important due to the complexity of heat transfer in biological tissues. In the past few years, there has been a growing interest among clinicians, mathematicians, and engineers regarding the use of computational and mathematical methods to simulate biological systems. Numerous medical proceedings also employ mathematical modeling and engineering techniques as a means to guarantee their safety and evaluate the associated risks effectively. This manuscript provides an analytical solution used for the first time to study the mechanism of biological thermal response during heat therapy on spheroidal skin tumor. The proposed method used a generalized thermoelasticity model with one relaxation time. The influence of relaxation times on the responses of diseased and healthy tissues is studied and interpreted graphically. Also, the impact of different laser irradiance on the thermal profile of the malignant tumor cells over a period of 2 minutes is interpreted graphically. To investigate the transfer of heat within biological tissues during the thermal therapy, the Laplace transform and inverse Laplace transform methods were applied. A comparison of the present generalized thermoelasticity model and different models based on Pennes bioheat transfer PBT shows that our proposed model yields more realistic and accurate predictions. The current model can be used to explain various therapeutic methods. [ABSTRACT FROM AUTHOR]

In this manuscript, the dynamic response of a long cylinder subjected to an asymmetric thermal shock is investigated within the framework of generalized micropolar thermoelasticity. The displacement and micro-rotation are assumed to vanish at the surface. Laplace transformation techniques are used to solve the problem. The solution is obtained in the transformed field using an innovative direct approach. Furthermore, we obtain the inverse transformations using a numerical method based on Fourier expansion. The obtained results are carefully presented through graphical representations and discussed extensively across different relaxation time values. It is evident that the relaxation time parameter significantly influences all the distributions. The displacement distributions are always continuous, whereas all other functions, including temperature variation, stress distribution, and micro-rotation, exhibit discontinuity at the wave front. The results obtained hold significant importance in various technological applications and in the manufacturing of mechanical components. [ABSTRACT FROM AUTHOR]

Nanostructured lipid carriers (NLCs) have been proven to significantly improve the bioavailability and efficacy of many drugs; however, they still have many limitations. These limitations could hinder their potential for enhancing the bioavailability of poorly water-soluble drugs and, therefore, require further amendments. From this perspective, we have investigated how the chitosanization and PEGylation of NLCs affected their ability to function as a delivery system for apixaban (APX). These surface modifications could enhance the ability of NLCs to improve the bioavailability and pharmacodynamic activity of the loaded drug. In vitro and in vivo studies were carried out to examine APX-loaded NLCs, chitosan-modified NLCs, and PEGylated NLCs. The three nanoarchitectures displayed a Higuchi-diffusion release pattern in vitro, in addition to having their vesicular outline proven via electron microscopy. PEGylated and chitosanized NLCs retained good stability over 3 months, versus the nonPEGylated and nonchitosanized NLCs. Interestingly, APX-loaded chitosan-modified NLCs displayed better stability than the APX-loaded PEGylated NLCs, in terms of mean vesicle size after 90 days. On the other hand, the absorption profile of APX (AUC0-inf) in rats pretreated with APX-loaded PEGylated NLCs (108.59 µg·mL−1·h−1) was significantly higher than the AUC0-inf of APX in rats pretreated with APX-loaded chitosan-modified NLCs (93.397 µg·mL−1·h−1), and both were also significantly higher than AUC0-inf of APX-Loaded NLCs (55.435 µg·mL−1·h−1). Chitosan-coated NLCs enhanced APX anticoagulant activity with increased prothrombin time and activated partial thromboplastin time by 1.6- and 1.55-folds, respectively, compared to unmodified NLCs, and by 1.23- and 1.37-folds, respectively, compared to PEGylated NLCs. The PEGylation and chitosanization of NLCs enhanced the bioavailability and anticoagulant activity of APX over the nonmodified NLCs; this highlighted the importance of both approaches. [ABSTRACT FROM AUTHOR]

Apixaban (Apx), an oral anticoagulant drug, is a direct factor Xa inhibitor for the prophylaxis against venous thromboembolism. Apx has limited oral bioavailability and poor water solubility. The goal of this study was to improve the formulation of an Apx-loaded nanostructured lipid carrier (NLC) to increase its bioavailability and effectiveness. As solid lipid, liquid lipid, hydrophilic, and lipophilic stabilizers, stearic acid, oleic acid, Tween 80, and lecithin were used, respectively. Utilizing Box–Behnken design, the effects of three factors on NLC particle size (Y1), zeta potential (Y2), and entrapment efficiency percent (Y3) were examined and optimized. The optimized formula was prepared, characterized, morphologically studied, and pharmacokinetically and pharmacodynamically assessed. The observed responses of the optimized Apx formula were 315.2 nm, −43.4 mV, and 89.84% for Y1, Y2, and Y3, respectively. Electron microscopy revealed the homogenous spherical shape of the NLC particles. The in vivo pharmacokinetic study conducted in male Wistar rats displayed an increase in AUC and Cmax by 8 and 2.67 folds, respectively, compared to oral Apx suspension. Moreover, the half-life was increased by 1.94 folds, and clearance was diminished by about 8 folds, which makes the NLC formula a promising sustained release system. Interestingly, the pharmacodynamic results displayed the superior effect of the optimized formula over the drug suspension with prolongation in the cuticle bleeding time. Moreover, both prothrombin time and activated partial thromboplastin time are significantly increased. So, incorporating Apx in an NLC formula significantly enhanced its oral bioavailability and pharmacodynamic activity. [ABSTRACT FROM AUTHOR]

We consider a 2D problem for an infinite body with a cylindrical cavity formed of a thermoelastic substance. The body is under the action of a nonsolenoidal body force. The theory used is that of Generalized Thermoelasticity. The surface is assumed to be traction free and subjected to an asymmetrical thermal shock. Laplace transform is used. The inversion process is carried out numerically. All the relevant functions are represented graphically. [ABSTRACT FROM AUTHOR]

A series of cationic polyurethane surfactants [PQ8‐18] were synthesized by the reaction of alkyl bromoacetate (namely: octyl‐, decyl‐, dodecyl‐, tetradecyl‐, hexadecyl‐, and octadecyl bromoacetate) as quaternizing agents and modified polyurethane contains tertiary amine species. Modified polyurethane was prepared by the reaction of toluene diisocyanate (TDI) and triethanol amine monomercaptoacetate. The chemical structures of the prepared surfactants were confirmed using elemental analysis, Fourier transform infrared spectroscopy (FTIR), and Proton nuclear magnetic resonance (1H NMR) spectroscopy. The molecular weight measurements of the prepared polymers showed that the segments of each polymer contain average 10 units of the urethane‐triethanol amine mercaptoacetate. The surface activities of the prepared surfactants including: surface tension (γ), effectiveness (πcmc), concentration at micelle formation (CMC), efficiency (Pc20), maximum concentration at the interface (Γmax), and the average area occupied by each surfactant molecule at the interface at equilibrium (Amin) of surfactants solutions were established at 25°C. The surface tension and the critical micelle concentration values of the prepared surfactants were gradually decreased by the gradual increase of their alkyl chain length. The prepared cationic surfactants showed efficient activity as inhibitors for dissolution of carbon steel in an acidic medium and also as a biocide against the growth of bacteria, fungi, and yeast. [ABSTRACT FROM AUTHOR]