Shape memory polymers have received widespread attention from researchers because of their low density, shape variety, responsiveness to the environment, and transparency. This study deals with heat-shape memory polymers (SMPs) based on polylactic acid (PLA) for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis. The solid isotropic material penalization method (SIMP) was applied to optimize the vascular scaffolds. Based on the torsional torque loading of Hyperworks Optistruct and the boundary conditions, the topological optimization model of a vascular scaffold unit was established. Forward and reverse hybrid modeling technology was applied to complete the final stent structure’s assembly. The glass transition temperature for the present SMPs is 42.15 °C. With the increase in temperature, the ultimate tensile strength of the SMPs is reduced from 29.5 MPa to 11.6 MPa. The maximum modulus at room temperature was around 34 MPa. Stress relaxation curves show that the material classification is a “thermoset” polymer. The superb mechanical properties, the transition temperature of the SMPs, and the recovery ratio made it a feasible candidate for a vascular scaffold. A circular tube based on the shape memory polymers was presented as an example for analyzing the recovery ratio in an unfolding state. A higher recovery ratio was obtained at a temperature of 65 °C with a tube thickness of 2 mm. Finally, the proposed porous vascular scaffold was successfully fabricated, assessed, and compared with the original and previously developed vascular scaffolds. The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. The tensile strength, Young’s modulus, and bending strength of the proposed scaffold were 29.5 MPa, 695.4 MPa, and 6.02 MPa, respectively. The results showed that the proposed scaffold could be regarded as a potential candidate for a vascular implantation.

This study communicates the structural, electronic, optical, and thermoelectric properties of a perovskite TlXF₃ (X: Zn, Sr) crystal structure using first-principles calculations. Both compounds were found structurally as well as thermodynamically stable in cubic phase. To check the kinetic stability, the phonon frequancy band structure is calculated which indicates that there is no negative frequency in the phonon spectrum, which confirms the dynamic stability of TlXF₃. The bandgaps of both compounds belong to insulating region. The TlSrF₃ exhibits direct bandgap of 4.37 eV at X symmetry point while TlZnF₃ possess indirect bandgap of 3.95 eV (M-X). Using HSE functional, the calculated electronic bandgaps of TlSrF₃ and TlZnF₃ are 5.74 eV(X-X) and 5.36 eV (M-X), respectively. The analysis of electronic states in band structure shows that for TlSrF₃, the top of valence band is composed of the F-p states whereas the states in lower potion of conduction band are impacted by the significant contribution of Tl-p orbital states. In case of TlZnF₃, the states near the valence band maxima and conduction band minima are coming mainly form Tl atom. The effect of spin–orbit coupling (SOC) on the electronic band structure is also considered. The SOC in the valance band is negligible, while in the conduction band it shows a dominant effect at Γ-point in both TlSrF₃ and TlZnF₃ compounds. The dependence of thermoelectric properties such as electrical conductivity σ, Seebeck coefficient (S), Power factor (PF), electronic thermal conductivity (κ) and figure-of-merit (ZT) as a function of carrier concentration and temperature are investigated. The optical properties were also studied to understand the response of TlXF₃ to incident photons of energies upto 14 eV. We conclude that the TlXF₃ are promising candidates for electronic, thermoelectric and optoelectronic devices.

Dental caries (or tooth decays) is a common oral disease in early childhood and adults of all ages, which is caused by long-term synergies of acid-producing bacteria and fermentable carbohydrates in the oral environment. The use of existing dental restorative materials (including silver amalgams, light-cured resins, and dental restorative composites) and dental restorative composites (including glass ionomers cement, despite being sealants, releasing fluoride and promoting remineralization) is commercially restricted due to their weak mechanical properties, poor abrasion resistance, low elastic modulus, improper shrinkage, less polishability, brittleness, poor wear resistance tensile strength, aesthetic etc. Therefore, the physical intercalation of nano-fillers with polymer resins in nanocomposites might be a better alternative, mainly due to the high surface area of nanofillers. The present work reports an economical hydro-solvo thermal combinatory method to prepare TiO2/PMMA nanocomposites with four distinct wt% (3%, 6%, 9% and 12%) of TiO2 nanofillers. Their comparative structural, morphological, and functional group analysis was carried out with that of pure PMMA by XRD, AFM, and FTIR, respectively. The physio-mechanical properties of the nanocomposites (including Young modulus, ultimate tensile strength, break strength, hardness value (HV), flexural strength, water absorption, density tests and polymerization shrinkage) were measured using UTM, ASTM D790 standard, the Archimedes method and ASTM D570 standard, respectively. Significant enhancement in Young’s modulus, ultimate tensile strength, break strength, hardness value (HV), and flexural strength were recorded as compared with that of the pure PMMA, achieving the optimum values (1.23 times in Young’s modulus, 2.38 times in UTS, 2.37 times in break strength, and 2 times in HV) for the nanocomposite with 9% TiO2 nanofiller. Similarly, significant reduction in water adsorption and polymerization shrinkage (linear decrease) was observed with increasing filler (TiO2) contents, which reveals the dimensional stability of nanocomposites, favorable for dental implants, and this is attributed to the effective bonding of TiO2 nanoparticles with the PMMA matrix. Such a tremendously enhanced physio-mechanical behavior of the TiO2/PMMA nanocomposite (particularly with 9 wt% TiO2 nanofiller) reveals its promising potential for use as a dental restorative material.