Thermodynamic Modeling and Mechanical Properties of Mg-Zn-{Y, Ce} Alloys: Review

Magnesium alloys are a strong candidate for various applications in automobile and aerospace industries due to their low density and specific strength. Micro-alloying magnesium with zinc, yttrium, and cerium enhances mechanical properties of magnesium through grain refinement and precipitation hardening. In this work, a critical review of magnesium-based binary systems including Mg-Zn, Mg-Y, Mg-Ce, Zn-Y, and Zn-Ce is presented. Based on the CALPHAD approach and first-principles calculations, thermodynamic modeling of Mg-Zn-Y and Mg-Zn-Ce ternary phase diagrams have been summarized. The influence of micro-alloying (yttrium and cerium) on the mechanical properties of magnesium is discussed. A comparison between mechanical properties of magnesium commercial alloys and magnesium–zinc–{yttrium and cerium} have been summarized in tables.

Hepatoprotective Effects of Bioflavonoid Luteolin Using Self-Nanoemulsifying Drug Delivery System

Luteolin (LUT) is a natural pharmaceutical compound that is weakly water soluble and has low bioavailability when taken orally. As a result, the goal of this research was to create self-nanoemulsifying drug delivery systems (SNEDDS) for LUT in an attempt to improve its in vitro dissolution and hepatoprotective effects, resulting in increased oral bioavailability. Using the aqueous phase titration approach and the creation of pseudo-ternary phase diagrams with Capryol-PGMC (oil phase), Tween-80 (surfactant), and Transcutol-HP (co-emulsifier), various SNEDDS of LUT were generated. SNEDDS were assessed for droplet size, polydispersity index (PDI), zeta potential (ZP), refractive index (RI), and percent of transmittance (percent T) after undergoing several thermodynamic stability and self-nanoemulsification experiments. When compared to LUT suspension, the developed SNEDDS revealed considerable LUT release from all SNEDDS. Droplet size was 40 nm, PDI was <0.3, ZP was −30.58 mV, RI was 1.40, percent T was >98 percent, and drug release profile was >96 percent in optimized SNEDDS of LUT. For in vivo hepatoprotective testing in rats, optimized SNEDDS was chosen. When compared to LUT suspension, hepatoprotective tests showed that optimized LUT SNEDDS had a substantial hepatoprotective impact. The findings of this investigation suggested that SNEDDS could improve bioflavonoid LUT dissolution rate and therapeutic efficacy.

Formulation and Optimization of Self Emulsifying Drug Delivery System For Effective Anthelmintic Therapy

The present study aims to develop and optimize a self-emulsifying drug delivery system for paediatric patients to improve the oral bioavailability of the anthelmintic drug, Praziquantel (PZQ) and to perform it’s in-vitro dissolution study. The solubility of PZQ was estimated in various vehicles to select proper component combination. Capmul MCM (oil), Cremophore RH40 (surfactant) and PEG400 (co-surfactant) were employed to construct pseudo-ternary phase diagrams. Eight formulations composed of Capmul MCM, at Smix ratios (1:1, 2:1 & 3:1) were selected. The optimized formulation F7 has a mean globule size 14.73 nm with a negative zeta potential -44.43 mV. The results indicated that PZQ loaded SEDDS, showed enhanced solubilization and nanosizing potential to improve the absorption of the drug.

Influence of Preparation Temperature on the Properties and Performance of Composite PVDF-TiO2 Membranes

Composite PVDF-TiO2 membranes are studied extensively in literature as effective anti-fouling membranes with photocatalytic properties. Yet, a full understanding of how preparation parameters affect the final membrane structure, properties and performance has not been realized. In this study, PVDF-TiO2 membranes (20 wt% TiO2/PVDF) were fabricated via the non-solvent-induced phase separation (NIPS) method with an emphasis on the preparation temperature. Then, a systematic approach was employed to study the evolution of the membrane formation process and membrane properties when the preparation temperature changed, as well as to establish a link between them. Typical asymmetric membranes with a high porosity were obtained, along with a vast improvement in the permeate flux compared to the neat PVDF membranes, but a reduction in mechanical strength was also observed. Interestingly, upon the increase in preparation temperature, a significant transition in membrane morphology was observed, notably the gradual diminution of the finger-like macrovoids. Other membrane properties such as permeability, porosity, thermal and mechanical properties, and compression behavior were also influenced accordingly. Together, the establishment of the ternary phase diagrams, the study of solvent–nonsolvent exchange rate, and the direct microscopic observation of membrane formation during phase separation, helped explain such evolution in membrane properties.

Influence of Asphaltenes on the Low-Sulphur Residual Marine Fuels’ Stability

The effects of asphaltenes from two heavy oil residues on the sedimentation stability of residual marine fuels were assessed and compared. As base components of residual marine fuels, the vacuum residue (VacRes) and visbreaking residue (VisRes) were taken. The heptane-insoluble fractions (HI-fractions), including asphaltenes, isolated from vacuum residue and visbreaking residue, were analyzed to determine the elemental composition (XRF) and cluster parameters (XRD). The results of the analysis of the parameters of the asphaltene cluster (HI-fraction) for vacuum residue and visbreaking residue showed that dγ – 6.1 and 5.9 Å, Lc – 26.72 and 20.78 Å, and La – 7.68 and 7.20 Å. The sedimentation stability of residual marine fuel was determined according to the ISO 10307-1-2009 (TSA) method and described using ternary phase diagrams. The ratio of stable compositions to the total number of possible compositions (with a step of 10 wt%) was 65/66 or 98.5% for residual marine fuel comprising a mixture VacRes/ULSD/LCGO (vacuum residue/ultra-low sulphur diesel/light catalytic gas oil). Meanwhile, the ratio of stable compositions to the total number of possible compositions was 38/66 or 57.6% for residual marine fuel comprising a mixture VisRes/ULSD/LCGO (visbreaking residue/ultra-low sulphur diesel/light catalytic gas oil).

In Vitro Evaluation of a Solid Supersaturated Self Nanoemulsifying Drug Delivery System (Super-SNEDDS) of Aprepitant for Enhanced Solubility

Aprepitant (APR) belongs to Class II of the Biopharmaceutical Classification System (BCS) because of its low aqueous solubility. The objective of the current work is to develop self-nanoemulsifying drug delivery systems (SNEDDS) of APR to enhance its aqueous solubility. Preformulation studies involving screening of excipients for solubility and emulsification efficiency were carried out. Pseudo ternary phase diagrams were constructed with blends of oil (Imwitor® 988), cosolvent (Transcutol® P), and various surfactants (Kolliphor® RH40, Kolliphor® ELP, Kolliphor® HS15). The prepared SNEDDS were characterized for droplet size and nanoemulsion stability after dilution. Supersaturated SNEDDS (super-SNEDDS) were prepared to increase the quantity of loaded APR into the formulations. HPMC, PVP, PVP/VA, and Soluplus® were used as polymeric precipitation inhibitors (PPI). PPIs were added to the formulations at 5% and 10% by weight. The influence of the PPIs on drug precipitation was investigated. In vitro lipolysis test was carried out to simulate digestion of formulations in the gastrointestinal tract. Optimized super-SNEDDS were formulated into free-flowing granules by adsorption on the porous carriers such as Neusilin® US2. In vitro dissolution studies of solid super-SNEDDS formulation revealed an increased dissolution rate of the drug due to enhanced solubility. Consequently, a formulation to improve the solubility and potentially bioavailability of the drug was developed.

Development and Characterization of Acetazolamide Nanoemulsion for Effective Ocular Delivery

Nanoemulsion has the potential of releasing the drug continuously, and they may easily permeate via the intense layers of the eye structure due to nano-size droplets, which makes nanoemulsion an effective drug delivery system for ocular delivery. The objective of our work was to prepare a nanoemulsion of acetazolamide for glaucoma treatment with enhanced efficacy as well as for continuous effect. Based on different compositions of oil (Olive Oil), surfactants (Tween-20), and co-surfactants (Transcutol P), forty-five test mixtures were made, water titration technique was employed for preparing the pseudo-ternary-phase diagrams. On the basis of these phase diagrams, twenty-five acetazolamide loaded nanoemulsion were formulated and examined for their nanosized droplets, PDI, zeta potential, viscosity, pH, transmittance and in-vitro drug release. The formulated nanoemulsion showed all the properties within the desired range i.e., droplet size (15.6 to 21.18), zeta potential (-15.5 to- 24.71), PDI (0.140 to 0.361), viscosity (3.234 ± 0.063to 5.174 ± 0.023cps), pH (6.922 ± 0.026to 7.033 ± 0.012), RI (1.379 ± 0.007 to 1.404 ± 0.006) and % transmittance was found (94.96± 0.6% to 96.68± 0.6%) and also the release rate of acetazolamide from nanoemulsion was found very good i.e., 81.59± 1.04% to 92.46± 0.33% after 24 hrs. The top four formulations having good drug release were selected for further evaluation of droplet sizes and which also fall in the nano range (15.68 to 21.18 nm). The study showed that it is possible to develop nanoemulsion of phenytoin drug, and the in-vitro drug release study showed that the prepared nanoemulsion had good bioavailability, sustained release and ability to target eye as an effective ocular delivery system.

Production of polylactic acid aerogels via phase separation and supercritical CO2 drying: thermodynamic analysis of the gelation and drying process

The application range of aerogels, especially in the life-science sector, can be extended by utilizing biocompatible polymers such as polylactic acid (PLA). However, the low glass transition temperature (Tg) of PLA and the challenging gelation techniques limit the application of supercritical CO2 (scCO2) drying and thus the PLA-aerogel production. The aim of this work is to overcome this challenge and to provide a better understanding of the thermodynamics of the process. Therefore, the gelation of amorphous PLA (PDLLA) and semicrystalline PLA (PLLA) via thermal-induced phase separation (TIPS) was studied. To identify polymer/solvent/antisolvent ratios suitable for gelation, thermodynamic modeling (PC-SAFT) was used to describe the corresponding ternary phase diagrams. scCO2 drying was used to preserve the mesoporous gel structure formed during the gelation. Due to the decrease in the Tg of PLA in the presence of CO2, this could not be applied to all gels. It was found that the critical parameter to enable the scCO2 drying of low Tg polymers is the crystallinity degree (Xc) of the polymer. Based on these results, some guidelines for producing aerogels from polymers with low Tg are formulated. Graphical abstract