In vitro bactericidal effect of ultrasonically sol–gel-coated novel CuO/TiO<Subscript>2</Subscript>/PEG/cotton nanocomposite for wound care

Protection against bacterial contamination remains a demand for healthcare textiles such as wound dressings to reduce or eliminate hospital-acquired infections related to antibiotic-resistant bacteria. We report herein a simple and straightforward in situ approach to deposit copper oxide and titanium oxide nanoparticles onto cotton fabric using a sonochemical-mediated sol–gel method. Modification of the cotton surface was achieved by incorporation of citric acid (CA) and polyethylene glycol (PEG) to improve the attachment of the nanoparticles and reduce the attachment of bacteria to the cotton surface, respectively. The resultant cotton fabric was used against Escherichia coli as a Gram-negative bacterium and Staphylococcus aureus as a Gram-positive bacterium in dark condition as an in vitro model for treatment of bacterial wound infection. The effects of different treatment parameters including duration and frequency of ultrasonic irradiation, surface modification with PEG and/or CA, and cotton chemical composition with different metal oxide molar ratios on the antibacterial activity of the treated cotton fabric were studied. All treated cotton fabrics showed antibacterial activity, with higher efficiency for those coated with CuO or CuO/TiO₂ (1:1 molar ratio) among the single metal oxide and composite-modified cotton fibers, respectively. Our results show that such functionalized cotton fibers could actively fight the spread of bacterial infections by preventing bacterial adhesion, enabling more efficient bonding, and ultrasonically promoting generation of nanoparticles and their strong adhesion to the fabric surface.     

The Role of Antioxidation and Immunomodulation in Postnatal Multipotent Stem Cell-Mediated Cardiac Repair

Oxidative stress and inflammation play major roles in the pathogenesis of coronary heart disease including myocardial infarction (MI). The pathological progression following MI is very complex and involves a number of cell populations including cells localized within the heart, as well as cells recruited from the circulation and other tissues that participate in inflammatory and reparative processes. These cells, with their secretory factors, have pleiotropic effects that depend on the stage of inflammation and regeneration. Excessive inflammation leads to enlargement of the infarction site, pathological remodeling and eventually, heart dysfunction. Stem cell therapy represents a unique and innovative approach to ameliorate oxidative stress and inflammation caused by ischemic heart disease. Consequently, it is crucial to understand the crosstalk between stem cells and other cells involved in post-MI cardiac tissue repair, especially immune cells, in order to harness the beneficial effects of the immune response following MI and further improve stem cell-mediated cardiac regeneration. This paper reviews the recent findings on the role of antioxidation and immunomodulation in postnatal multipotent stem cell-mediated cardiac repair following ischemic heart disease, particularly acute MI and focuses specifically on mesenchymal, muscle and blood-vessel-derived stem cells due to their antioxidant and immunomodulatory properties.     

Residence Time and Concentration Distribution in a Kenics Static Mixer

Static mixers, often referred to as motionless mixers, are in-line mixing devices that consist of mixing elements inserted into a length of pipe. Most of the experimental works in this field have concentrated on establishing design guidelines and pressure drop correlations. Due to experimental difficulties, few articles have been published on the investigation of the flow and mixing mechanisms. In this work, a Kenics KMX static mixer was utilized to study concentration and residence time distribution (RTD) and effect of Reynolds number on mixing. The static mixer had six mixing elements arranged in-line along the length of the tube, and the angle between two neighboring elements was 90°. The length of the mixer was 0.98 m with internal and external diameters of 5.0 cm and 6.0 cm, respectively. The main continuous fluid was water, and NaCl solution was used as a tracer. All experiments were conducted with three replications at three Reynolds numbers, Re = 1188.71, 1584.95, and 1981.19. A dispersion model was used to model the RTD data. The experimental results were compared with the model results and reasonable agreement was achieved.     

Kinetic and CFD Modeling of Exhaust Gas Reforming of Natural Gas in a Catalytic Fixed-Bed Reactor for Spark Ignition Engines

Fuel reforming is an attractive method for performance enhancement of internal combustion engines fueled by natural gas, since the syngas can be generated inline from the reforming process. In this study, 1D and 2D steady-state modeling of exhaust gas reforming of natural gas in a catalytic fixed-bed reactor were conducted under different conditions. With increasing engine speed, methane conversion and hydrogen production increased. Similarly, increasing the fraction of recirculated exhaust gas resulted in higher consumption of methane and generation of H₂ and CO. Steam addition enhanced methane conversion. However, when the amount of steam exceeded that of methane, less hydrogen was produced. Increasing the wall temperature increased the methane conversion and reduced the H₂/CO ratio.     

Effect of nano‐silica on gas permeation properties of polyether‐based polyurethane membrane in the presence of esterified canola oil diol as a nucleation agent for hard segments

In this research esterified canola oil diol (COD) was used to synthesize a green thermoplastic polyurethane. The mixture of synthesized COD as a polyester and polytetramethylene‐glycol as a polyether with different molar ratios were used to synthesize a thermoplastic polyurethane. Membranes were prepared by solution casting technique and nano‐silica particles were used to improve their gas separation performance. The effects of COD segments on phase separation and thermal properties of blocky segments of polyurethanes were evaluated using Fourier transform infrared spectroscopy and thermal gravimetric analysis. Results showed that phase separation behavior of the synthesized polyurethane was significantly increased with COD content. The COD segments showed high tendency to interact with hard segments of polyurethane in a way that new domains with higher thermal stability is created. Permeability of pure CO₂, CH₄, N₂, and He gases were taken using constant pressure method at different pressures. Nano‐silica particles showed high inclination to interact with COD segments and significantly influenced the phase separation as well as gas permeation properties of polyurethane. Interactions of nano‐silica particles with the soft segments of polyurethane increased the glassy behavior of polymer and improved the CO₂/CH₄, CO₂/N₂, and CO₂/He ideal selectivities (permselectivities). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45979.     

Electrochemical oxidation of terbium(III) in aqueous media: influence of supporting electrolyte on oxidation potential and stability

Journal of Applied Electrochemistry - Apart from the generally dominant trivalent oxidation state, several lanthanides can occur in divalent or tetravalent states as well. Changing the valence...     

Crosslinked methyl methacrylate/ethylene glycol dimethacrylate polymer compounds with a macroazoinitiator

A silane‐containing diamine, bis(p‐aminophenoxy) diphenylsilane (BADPS), was prepared by the condensation of p‐aminophenol with dichlorodiphenyl silane in the presence of triethylamine. Then, BADPS was condensed with 4,4‐azobis(4‐cyanopentanoyl chloride) to prepare macroazoinitiators containing silane units (Si–MAIs). A series of poly(methyl methacrylate) gels containing silane were derived by the solution free‐radical crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate monomers initiated by these macroazoinitiators at a total monomer concentration of 6 mol/L and 80°C. Si–MAIs were characterized with ¹H‐NMR and ¹³C‐NMR spectroscopy, and the structural characteristics of the gels were also examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of Ti3SiC2 on the ablation behavior and mechanism of Cf-C-SiC-Ti3SiC2 composites under oxyacetylene torch at 3000 °C

In this research, ablation resistance of C_f-C-SiC and C_f-C-SiC-Ti₃SiC₂ composites, fabricated by liquid silicon infiltration (LSI) method were investigated. The infiltration process was conducted at 1500?°C for 30?min and then the samples were annealed at 1350?°C. X-ray diffraction (XRD) technique and scanning electron microscopy (SEM) were utilized in order to investigate the phase composition and microstructure of the ablated samples, respectively. When compared with C_f-C-SiC composite, results showed that mass and linear ablation rates of C_f-C-SiC-Ti₃SiC₂ composite have been improved by 50% and 37.5%, respectively. The mass and linear ablations rates of C_f-C-SiC composite were reached to 23.8?mg/s and 0.096?mm/s, respectively, while these values for C_f-C-SiC-Ti₃SiC₂ were reached to 11.8?mg/s and 0.06?mm/s, respectively. Microscopic investigations showed that formation of protective oxide layer and its stability on the surface of MAX-containing composite are the main reasons for improvement of ablation properties. While the oxide film formed on C_f-C-SiC composite has been blown away by flame.     

Synthesis,Characterization, Magnetic Properties,and Applications of La0.85Ce0.15FeO3 Perovskite in Heavy Metal Pb2+ Removal

Journal of Superconductivity and Novel Magnetism - Perovskite La0.85Ce0.15FeO3 was synthesized with crystallite size 23&nbsp;nm by flash combustion technique. The obtained sample was...