Palladium-PEPPSI-NHC Complexes Bearing Imidazolidin-2-Ylidene Ligand: Efficient Precatalysts for the Direct C5-Arylation of N-Methylpyrrole-2-Carboxaldehyde

Catalysis Letters - The Pd-catalyzed direct arylation of pyrroles is an important research field for organic synthesis and catalysis chemistry. However, imidazolidin-2-ylidene based Pd-NHC...     

Poly(lactide)/cellulose nanocrystal nanocomposites by high-shear mixing

There is currently considerable interest in developing stiff, strong, tough, and heat resistant poly(lactide) (PLA) based materials with improved melt elasticity in response to the increasing demand for sustainable plastics. However, simultaneous optimization of stiffness, strength, and toughness is a challenge for any material, and commercial PLA is well-known to be inherently brittle and temperature-sensitive and to show poor melt elasticity. In this study, we report that high-shear mixing with cellulose nanocrystals (CNC) leads to significant improvements in the toughness, heat resistance, and melt elasticity of PLA while further enhancing its already outstanding room temperature stiffness and strength. This is evidenced by (i) one-fold increase in the elastic modulus (6.48 GPa), (ii) 43% increase in the tensile strength (87.1 MPa), (iii) one-fold increase in the strain at break (∼6%), (iv) two-fold increase in the impact strength (44.2 kJ/m²), (v) 113-fold increase in the storage modulus at 90°C (787.8 MPa), and (vi) 10³-fold increase in the melt elasticity at 190°C and 1 rad/s (∼10⁵ Pa) via the addition of 30 wt% CNC. It is hence possible to produce industrially viable, stiff, strong, tough, and heat resistant green materials with improved melt elasticity through high-shear mixing.     

An in vitro evaluation of Genipin-crosslinked and Hypericum perforatum incorporated novel membranes for skin tissue engineering applications

Incorporating medicinal plant extracts in membranes have a great potential as scaffolds for tissue engineering applications or vehicles for delivering therapeutic agents. Herein, Hypericum perforatum oil (0.25, 0.50, % vol/vol) loaded membranes were developed with Polyvinyl alcohol and chitosan polymer, where Genipin works as a chemical crosslinker to obtain a wound dressing material with acceptable characterization properties. Chemical groups, surface morphology, water uptake capacity, water vapor permeability rate, hydrophilicity, and mechanical properties of membranes were thoroughly investigated. Increasing oil concentration had a significant effect on the water uptake, surface morphology. and water vapor permeability rate of the membranes. Cytocompatibility of the membrane was also investigated with mouse embryonic fibroblasts (MEF) by 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for direct and indirect cell culture studies. SEM was used to investigate the cell morphology on the membranes. The MTT assay findings prove that Genipin crosslinked H. perforatum oil loaded scaffolds are highly biocompatible and enhance the adhesion and proliferation of MEF cells. In addition to this, the genotoxicity test was performed to show DNA fragmentation. Results showed that the H. perforatum oil loaded polyvinyl alcohol-chitosan membrane presents suitable properties for potential skin tissue engineering applications.     

Determination of Electrical and Photoelectrical Properties of Schottky Diodes Made Using New Chitin Derivatives Synthesized as Interface Layer

Silicon - 5-(2,4-dichlorophenyl)-2-furoic acid and anthraquinone-2-carboxylic acid were reacted separately with chitin. The synthesized products were characterized by various spectroscopic methods...     

Stress wave propagation in adhesively bonded functionally graded cylinders: an improved model

This study presents an improved mathematical model to analyse the stress wave propagation in adhesively bonded functionally graded (FG) circular cylinders (butt joint) under an axial impulsive load. The volume fractions of the material constituents in the upper and lower cylinders were functionally tailored through the thickness of each cylinder using a power-law. The effective material properties of both cylinders, which are made of aluminum (Al) and silicon carbide (SiC), at any point were predicted by using the Mori–Tanaka homogenization scheme. In this improved model, the governing equations of the wave propagation include the spatial derivatives of local mechanical properties and were discretized by means of the finite difference method. The influence of these spatial derivatives and the compositional gradient exponent on the displacement and stress distributions of the joint was investigated. The material composition variations of both cylinders affected the displacement and stress fields whereas the compositional gradient exponent had a minor effect. The stress concentrations were alleviated in time, the displacement and stress distributions/variations around/along the upper and lower cylinder-adhesive interfaces were significantly affected by the adhesive layer. The spatial derivatives also affected the temporal histories of the displacement and stress components evaluated at the selected critical points of the upper cylinder, adhesive layer and lower cylinder. The consideration of the spatial local material derivatives provided a more accurate mathematical model of wave propagations through the graded layered structures.     

Designing carbon-supported Fe2O3 anodes for lithium ion batteries

Journal of Applied Electrochemistry - In this study, within the defined orthogonal array of Taguchi design, the hydrothermal process parameters have been optimized for fabricating the smallest...