Schiff base complex of Cu immobilized on MCM-41 as reusable catalyst for efficient oxidative coupling of thiols and oxidation of sulfides using hydrogen peroxide

Schiff base complex of copper-functionalized MCM-41 (Cu-complex@MCM-41) was synthesized and used as an efficient and novel heterogeneous catalyst for the oxidative coupling of thiols into corresponding disulfides and oxidation of sulfides to sulfoxides using hydrogen peroxide (H₂O₂) as the oxidant. An aliphatic and aromatic series of sulfides and thiols including various functional groups were successfully converted into corresponding products. The all products were obtained in good to excellent yields. The mesoporous catalyst is characterized by FT-IR spectroscopy, BET, XRD, SEM, EDS and TGA. Recovery of the catalyst is easily achieved by simple filtration and reused for several consecutive runs without significant loss of its catalytic efficiency.     

Visible Light-Induced Degradation of Methylene Blue in the Presence of Photocatalytic ZnS and CdS Nanoparticles

ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight) was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles after 6 h irradiation time was about 73% with a reaction rate of 3.61 × 10⁻³ min⁻¹. Higher degradation efficiency and reaction rate were achieved by increasing the amount of photocatalyst and initial pH of the solution.     

Formulation Optimization of a Palm-Based Nanoemulsion System Containing Levodopa

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%–12% w/w), lecithin (1%–3% w/w), and Cremophor EL (0.5%–1.5% w/w) as well as the preparation method; addition rate (2–20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.     

Enhanced shape memory effect of poly(L-lactide-co-ε-caprolactone) biodegradable copolymer reinforced with functionalized MWCNTs

Data from comprehensive thermomechanical tests of poly(L-lactide-co-ε-caprolactone) biodegradable shape memory polymer (SMP) reinforced with pristine and functionalized multiwalled carbon nanotubes (MWCNTs) are reported. The SMP specimens tested up to 500% strain and between 25 °C and 70 °C temperatures. The incorporation of functionalized MWCNTs leads to the best overall reinforcing effect in tensile modulus, yield stress, tensile strength and elongation at failure. Thermo mechanical experiments resulted that the functionalized MWCNTs increased the glass transition range of composites and changed the melting point of composites slightly. The crystallinity of composites was increased with increment of MWCNTs in composites. The shape fixity and shape recovery of composites increased slightly, while the recovery stress increased 46%. It is found that the functionalized MWCNTs prepare an effective physical cross linking and switching segments in polymer composites.     

Pure Hydrogen and Propylene Coproduction in Catalytic Membrane Reactor-Assisted Propane Dehydrogenation

Propane dehydrogenation on a commercial Pt-Sn/Al₂O₃ catalyst in a Pd-Ag membrane reactor is considered. A mathematical model is developed to evaluate the performance of the catalytic membrane reactor for the process of propane dehydrogenation. Design and operating conditions are systematically evaluated for key performance metrics such as propane conversion, propylene selectivity, hydrogen selectivity, and hydrogen recovery under different operating conditions. The results confirm that the high performance of the membrane reactor is related to the continuous removal of hydrogen from the reaction zone to shift the reaction equilibrium towards the formation of more propylene and hydrogen.     

Ni-Rhodanine Complex Supported on FSM-16 as Mesoporous Silica Support: Synthesis,Characterization and Application in Synthesis of Tri and Tetrasubstituted Imidazoles and 3,4-Dihydropyrimidine-2-(1H)-Ones

A new, efficient and recoverable heterogeneous catalyst was successfully synthesized by functionalization of mesoporous silica FSM-16. The FSM-16/CPTMS-Rh-     

The development of FtsZ inhibitors as potential antibacterial agents

The emergence and prevalence of bacterial resistance has resulted in a clear demand for novel antibacterial drugs. As a tubulin homologue, FtsZ is an essential cell-division protein in prokaryotic organisms and is showing increasing promise as a target for antibacterial drug discovery. This review describes the role of FtsZ in bacterial cytokinesis and various FtsZ inhibitors, with particular focus on their discovery, antibacterial activities, mechanisms of action, synthetic methods, and representative analogues.     

Optimization of waste quail eggshells as biocomposites for polyaniline in ammonia gas detection

A simple, cost-effective, and novel chemical sensor for ammonia (NH₃) gas detection was developed from polyaniline (PANI)/quail eggshell (QES) composites. QES is a natural waste enriched in calcium carbonate. In this work, pure PANI was synthesized from chemical oxidation method and PANI/QES composites were prepared from physical mixing of QES with the synthesized PANI at different mass ratio. A series of complementary techniques including Fourier transform infrared and ultraviolet-visible spectrometers, scanning electron microscope with energy dispersive detection coupled with mapping, thermogravimetric analysis, and X-ray diffractometer were used to characterize the physicochemical and textural properties of the biocomposites. From the results, PANI/QES composite with a mass ratio of 1 exhibited the lowest NH₃ detection limit of 5.24 ppm with a linear correlation coefficient (R²) of close to unity (0.9932) between the signal and NH₃ gas concentration. As a whole, the PANI/QES biocomposites synthesized from this work exhibited excellent selectivity toward NH₃ gas even in the presence of other gas impurities, such as acetone, ethanol, and hexane. For the sensor reusability, the PANI/QES biocomposites can be reused in the application of NH₃ gas detection for at least 4 cycles.     

Polyacrylonitrile/α-Fe2O3 Hybrid Photocatalytic Composite Adsorbents for Enhanced Dye Removal

The potential of a novel α-Fe₂O₃/polyacrylonitrile (PAN) hybrid composite adsorbent to eliminate methylene blue (MB) from aqueous solution was evaluated. PAN was selected as the base composite. The presence of α-Fe₂O₃ as nanophotocatalyst on the surface of PAN introduced an efficient photocatalytic hybrid composite adsorbent for degrading MB. Effects of α-Fe₂O₃ nanopowder loading, pH, temperature, MB initial concentration, solar light, and contact time were investigated. Langmuir, Freundlich, and Temkin isotherms were applied to analyze the adsorption behavior. The Freundlich equation provided the best correlation with experimental data. Pseudo-first-order, pseudo-second-order, and intraparticle models were employed. Thermodynamic studies indicated an endotherm and spontaneous adsorption process in a defined temperature range.