Bilayer regenerated cellulose/quaternized chitosan-hyaluronic acid/collagen electrospun scaffold for potential wound healing applications.

In this study, a bilayer electrospun scaffold has been prepared using regenerated cellulose (RC)/quaternized chitosan (CS) as the primary layer and collagen/hyaluronic acid (HA) as the second layer. An approximate 48 mol% substituted (estimated from 1H NMR) quaternized CS was used in this study. Both layers were crosslinked with EDC/NHS, reflecting an increase in UTS (2.29 MPa for the bilayer scaffold compared to 1.82 MPa for the RC scaffold). Initial cell viability, cell adhesion and proliferation, FDA staining for live cells, and hydroxyproline release rate from cells were evaluated with L929 mouse fibroblast cells. Also, detailed in vitro studies were performed using HADF cells, which include MTT Assay, Live/Dead imaging, DAPI staining, gene expression of PDGF, VEGF-A, and COL1 in RT-PCR, and cell cycle analysis. The collagen/HA-based bilayer scaffold depicted a 9.76-fold increase of VEGF-A compared to a 2.1-fold increase for the RC scaffold, indicating angiogenesis and vascularization potential. In vitro scratch assay was performed to observe the migration of cells in simulated wounds. Antimicrobial, antioxidant, and protease inhibitory activity were further performed, and overall, the primary results highlighted the potential usage of bilayer scaffold in wound healing applications.

Service life assessment of yttria stabilized zirconia (YSZ) based thermal barrier coating through wear behaviour.

Countless research has suggested Yttria-stabilized Zirconia (YSZ) to be a top candidate for being implemented as thermal barrier coatings (TBC). However, when exposed to prolonged service, temperature and stress variations succeed in initiating a catastrophic phase transformation from tetragonal to monoclinic structure in Zirconia. Hence, the estimation of endurance for YSZ-based TBC is necessary to minimize failure in such situations. The main purpose of this research was to determine the relationship between tribological investigations and the estimated lifespan of YSZ coatings accurately. The study used various methods such as wear resistance testing, optical profilometry, specific wear rate, and coefficient of friction to estimate the maximum durability of TBCs. The research also provided insights into the composition and microstructure of the TBC system and found the optimized concentration of Yttrium doping to be 3.5 wt %. The study discovered that erosion was the main cause of roughness depreciation from SN to S1000. The estimation of the service life was primarily made based on optical profilometry, specific wear rate (SWR), coefficient of friction (COF) and wear resistance values which were further supported by the results of chemical characterization of the samples through electron dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS) and X-Ray Diffraction (XRD) analysis. The results were reliable and accurate and suggested future areas of investigation, such as 3D profilometry for surface roughness and thermal conductivity evaluation using laser-assisted infrared thermometers.

Unified torque scaling in counter-rotating suspension Taylor-Couette flow.

Torque measurements are reported for the Taylor-Couette flow of a neutrally buoyant non-colloidal suspension in the counter-rotation regime up to a particle volume fraction of [Formula: see text]. A unified scaling relation for the dimensionless torque (the pseudo-Nusselt number) of the form [Formula: see text] is shown to hold over a range of Taylor numbers [Formula: see text] that covers primary, secondary and tertiary bifurcating states; here, [Formula: see text] is the reduced Taylor number, [Formula: see text] is the critical Taylor number at primary bifurcation and [Formula: see text] is the relative viscosity of the suspension. Possible effects of flow transitions and inhomogeneous distribution of particles on torque scaling are discussed. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (part 1)'.

Effects of surface patterning and topography on the cellular functions of tissue engineered scaffolds with special reference to 3D bioprinting.

The extracellular matrix (ECM) of the tissue organ exhibits a topography from the nano to micrometer range, and the design of scaffolds has been inspired by the host environment. Modern bioprinting aims to replicate the host tissue environment to mimic the native physiological functions. A detailed discussion on the topographical features controlling cell attachment, proliferation, migration, differentiation, and the effect of geometrical design on the wettability and mechanical properties of the scaffold are presented in this review. Moreover, geometrical pattern-mediated stiffness and pore arrangement variations for guiding cell functions have also been discussed. This review also covers the application of designed patterns, gradients, or topographic modulation on 3D bioprinted structures in fabricating the anisotropic features. Finally, this review accounts for the tissue-specific requirements that can be adopted for topography-motivated enhancement of cellular functions during the fabrication process with a special thrust on bioprinting.

Crisis-induced flow reversals in magnetoconvection.

We report the occurrence of flow reversals induced by the attractor-merging crisis in Rayleigh-Bénard convection of electrically conducting low-Prandtl-number fluids in the presence of a uniform external horizontal magnetic field. The simultaneous collision of two coexisting chaotic attractors with an unstable fixed point and its associated stable manifold takes place in the higher-dimensional phase space of the system, leading to a single merged chaotic attractor. The effect of strength of the magnetic field on the flow reversal phenomena is also explored in detail.

Effects of Processing Parameters of 3D Bioprinting on the Cellular Activity of Bioinks.

In this review, few established cell printing techniques along with their parameters that affect the cell viability during bioprinting are considered. 3D bioprinting is developed on the principle of additive manufacturing using biomaterial inks and bioinks. Different bioprinting methods impose few challenges on cell printing such as shear stress, mechanical impact, heat, laser radiation, etc., which eventually lead to cell death. These factors also cause alteration of cells phenotype, recoverable or irrecoverable damages to the cells. Such challenges are not addressed in detail in the literature and scientific reports. Hence, this review presents a detailed discussion of several cellular bioprinting methods and their process-related impacts on cell viability, followed by probable mitigation techniques. Most of the printable bioinks encompass cells within hydrogel as scaffold material to avoid the direct exposure of the harsh printing environment on cells. However, the advantages of printing with scaffold-free cellular aggregates over cell-laden hydrogels have emerged very recently. Henceforth, optimal and favorable crosslinking mechanisms providing structural rigidity to the cell-laden printed constructs with ideal cell differentiation and proliferation, are discussed for improved understanding of cell printing methods for the future of organ printing and transplantation.

Transitions in overstable rotating magnetoconvection.

The classical Rayleigh-Bénard convection (RBC) system is known to exhibit either subcritical or supercritical transition to convection in the presence or absence of rotation and/or magnetic field. However, the simultaneous exhibition of subcritical and supercritical branches of convection in plane layer RBC depending on the initial conditions, to the best of our knowledge, has not been reported so far. Here, we report the phenomenon of simultaneous occurrence of subcritical and supercritical branches of convection in overstable RBC of electrically conducting low Prandtl number fluids (liquid metals) in the presence of an external uniform horizontal magnetic field and rotation about the vertical axis. Extensive three-dimensional (3D) direct numerical simulations (DNS) and low-dimensional modeling of the system, performed in the ranges 750≤Ta≤3000 and 0

Corrosion Characteristics of Copper-Added Austempered Gray Cast Iron (AGCI).

The aim of this investigation was to assess the corrosion behavior of gray cast iron (GCI) alloyed with copper. Alloyed GCI specimens were austempered isothermally at varying temperatures. After austenitizing at 927 °C, the samples were austempered at different temperatures ranging from 260 to 385 °C with an interval of 25 °C for 60 minutes. As a result, these samples developed an ausferrite matrix with different percentages of austenite. The resulting microstructures were evaluated and characterized by optical microscope (OM), scanning electron microscope (SEM), and X-ray diffraction (XRD). The corrosion characteristics were determined using potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) of these samples. These tests were carried out in a medium of 0.5 M H2SO4 and 3.5% NaCl solution. It was observed from the potentiodynamic polarization results that with increasing austempering temperature, the corrosion rate decreased. All results of the EIS were in accordance with a constant phase element (CPE) model. It was found that with an increase in austempering temperature, the polarization resistance (Rp) increased. The austenite content was also found to influence the corrosion behavior of the austempered gray cast iron (AGCI).

Polysaccharides from Dolichos biflorus Linn and Trachyspermum ammi Linn seeds: isolation, characterization and remarkable antimicrobial activity.

Polysaccharides are structurally complex and essential constituents of life, and therefore, studies directed to these kinds of molecules have received scientific attention. Despite an easy availability of Dolichos biflorus Linn and Trachyspermum ammi (Linn) seeds isolation, characterization and antimicrobial studies of polysaccharides derived from these two natural sources have not been investigated. Therefore, we report here isolation of polysaccharides, their purification and characterization from Dolichos biflorus Linn and Trachyspermum ammi (Linn) seeds. Gel permeation chromatography, GC-MS, SEM, XRD, EDX and FT-IR analyses show the presence of three pentose sugar such as D-ribose, D-arabinose, D-xylose and hexose sugar such as D-mannose, D-galactose and D-glucose. Unprecedented antimicrobial activity of these polysaccharides against Gram positive bacteria such as Staphylococcus aureus and Bacillus subtilis and Gram negative bacteria such as Escherichia coli and Pseudomonas aeruginosa are established.