Antioxidant and antibacterial activity evaluation of 3‐hydroxybenzaldehyde: the product of thymol oxidation by a new magnetic nanocatalyst

In this study maghemite nanoparticles were synthesised, they were first coated by sodium alginate and then by chitosan. Then acetanilide was introduced to maghemite nanoparticles that were coated by alginate and chitosan. Finally a silver complex was made with acetanilide and the magnetic nanocatalyst was synthesised. This nanocatalyst was used for the oxidation of thymol, then antioxidant and antibacterial properties of the oxidation product were assessed. Characterisation of this nanocatalyst was performed by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffractometer, scanning electron microscope (SEM) and value stream mapping. Creation of the product was confirmed by FT‐IR and gas chromatography‐mass spectroscopy. According to SEM, the size of the nanocatalyst was in the range of 46–70 nm. 3‐hydroxybenzaldehyde was obtained from the oxidation of thymol. It had antioxidant property as evident from Di (phenyl) – (2, 4, 6‐trinitrophenyl) iminoazanium and the Folin–Ciocalteu method. Diffusion and dilution methods were used for the evaluation of the antibacterial activity. It was obvious from MIC that gram negative strains were more resistant than gram positive ones, and from minimum bactericidal concentration, it was obvious that Escherichia coli was the most resistant gram negative strain, and Bacillus subtilis was the most resistant gram positive strain.Inspec keywords: nanoparticles, iron compounds, magnetic particles, nanomagnetics, antibacterial activity, oxidation, organic compounds, Fourier transform infrared spectra, X‐ray diffraction, scanning electron microscopy, chromatography, diffusion, mass spectroscopic chemical analysis, microorganisms, catalysts, nanofabricationOther keywords: maghemite nanoparticles, sodium alginate, chitosan, acetanilide, magnetic nanocatalyst, thymol oxidation, antioxidant properties, antibacterial activity, Fourier transform infrared spectroscopy, X‐ray diffractometer, scanning electron microscope, value stream mapping, FTIR, gas chromatography‐mass spectroscopy, 3‐hydroxybenzaldehyde, Folin–Ciocalteu method, diffusion, dilution, gram negative strains, Escherichia coli, Bacillus subtilis, gram positive strain, Fe₂ O₃      

Compressive properties of a new metal–polymer hybrid material

Compressive properties of a new hybrid material, fabricated through filling of an aluminum foam with a thermoplastic polymer, are investigated. Static (0.01 s⁻¹) and dynamic (100 s⁻¹) compression testing has been carried out to study the behavior of the hybrid material in comparison with its parent foam and polymer materials. Considering the behavior of metal foams, the point on a compressive stress–strain curve corresponding to the minimum cushion factor is defined as the “densification” point. The analysis of the stress–strain curves provides insight into the load carrying and energy absorption characteristics of the hybrid material. At both strain rates, the hybrid is found to carry higher stresses and absorb more energy at “densification” than the foam or polymer.     

Effect of Joining Atmosphere in Transient Liquid Phase Bonding of Inconel 617 Superalloy

Metallurgical and Materials Transactions B - In the present paper, transient liquid phase (TLP) bonding of Inconel 617 alloy under the different furnace atmospheres of vacuum, argon gas, and air...     

Laboratory and field investigation of the effect of geogrid-reinforced ballast on railway track lateral resistance

Continuous welded rail (CWR) tracks have particular advantages over common tracks with jointed rails such as increased ride comfort, reduced noise and vibration and decreased maintenance costs due to the removal of joints in rail connections. Alternatively, some complications associated with CWR tracks, for instance increased lateral forces, are the main reason of track buckling and its subsequent lateral deformation. These problems are usually more severe in curved tracks. In order to overcome the large lateral forces caused by temperature deviations of CWR tracks which results in railway vehicle instability, the ballasted track lateral resistance should be improved. Among the various methods proposed in this area, no specific study has been carried out on the effect of geogrid reinforcement on ballasted track lateral resistance. Thus, the present research was allocated to investigating the effect of geogrid on the lateral resistances of both single tie and track panel via laboratory and field tests. In this regard, at the first stage, the ballast layer was reinforced with various number of geogrid layers, the effect of which was investigated by conducting the single tie push test (STPT) in the lab environment to assess the optimum number of geogrid layers and their installation levels along the ballast layer thickness. Afterwards, a test track was executed in the field including various sections which were reinforced in the same way as the lab tests. Consequently, many STPTs and track panel displacement tests (TPDTs) were accomplished. As a result, the STPTs in the lab and field confirmed more than 31% and 42% increase in single tie lateral resistance for ballast layers reinforced respectively with one and two geogrid layers, while these values were reached to 29% and 40% in the case of TPDT.     

Generation of a 3D error compensation grid from ISO 230-1 error parameters obtained by a SAMBA indirect calibration and validated by a ball-bar spherical test

Tool path deviation reduces machined parts quality. To enhance machine tool accuracy, compensation tables are provided in most controllers to automatically     

Effect of lactic acid chain length on thermomechanical properties of star‐LA‐xylitol resins and jute reinforced biocomposites

Star‐shaped bio‐based resins were synthesized by direct condensation of lactic acid (LA) with xylitol followed by end‐functionalizing of branches by methacrylic anhydride with three different LA chain lengths (3, 5 and 7). The thermomechanical and structural properties of the resins were characterized by ¹³C NMR, Fourier transform IR spectroscopy, rheometry, DSC, dynamic mechanical analysis (DMA), TGA and flexural and tensile tests. An evaluation of the effect of chain length on the synthesized resins showed that the resin with five LAs exhibited the most favorable thermomechanical properties. Also, the resin's glass transition temperature (103 °C) was substantially higher than that of the thermoplast PLA (ca 55 °C). The resin had low viscosity at its processing temperature (80 °C). The compatibility of the resin with natural fibers was investigated for biocomposite manufacturing. Finally, composites were produced from the n5‐resin (80 wt% fiber content) using jute fiber. The thermomechanical and morphological properties of the biocomposites were compared with jute‐PLA composites and a hybrid composite made of the impregnated jute fibers with n5 resin and PLA. SEM and DMA showed that the n5‐jute composites had better mechanical properties than the other composites produced. Inexpensive monomers, good thermomechanical properties and good processability of the n5 resin make the resin comparable with commercial unsaturated polyester resins. © 2017 Society of Chemical Industry     

Synthesis and characterization of methacrylated star‐shaped poly(lactic acid) employing core molecules with different hydroxyl groups

A set of novel bio‐based star‐shaped thermoset resins was synthesized via ring‐opening polymerization of lactide and employing different multi‐hydroxyl core molecules, including ethylene glycol, glycerol, and erythritol. The branches were end‐functionalized with methacrylic anhydride. The effect of the core molecule on the melt viscosity, the curing behavior of the thermosets and also, the thermomechanical properties of the cured resins were investigated. Resins were characterized by Fourier‐transform infrared spectroscopy, ¹³C‐NMR, and ¹H‐NMR to confirm the chemical structure. Rheological analysis and differential scanning calorimetry analysis were performed to obtain the melt viscosity and the curing behavior of the studied star‐shaped resins. Thermomechanical properties of the cured resins were also measured by dynamic mechanical analysis. The erythritol‐based resin had superior thermomechanical properties compared to the other resins and also, lower melt viscosity compared to the glycerol‐based resin. These are of desired characteristics for a resin, intended to be used as a matrix for the structural composites. Thermomechanical properties of the cured resins were also compared to a commercial unsaturated polyester resin and the experimental results indicated that erythritol‐based resin with 82% bio‐based content has superior thermomechanical properties, compared to the commercial polyester resin. Results of this study indicated that although core molecule with higher number of hydroxyl groups results in resins with better thermomechanical properties, number of hydroxyl groups is not the only governing factor for average molecular weight and melt viscosity of the uncured S‐LA resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45341.     

Polymeric mixed matrix membranes containing zeolites as a filler for gas separation applications: A review

Polymeric membrane technology has received extensive attention in the field of gas separation, recently. However, the tradeoff between permeability and selectivity is one of the biggest problems faced by pure polymer membranes, which greatly limits their further application in the chemical and petrochemical industries. To enhance gas separation performances, recent works have focused on improving polymeric membranes selectivity and permeability by fabricating mixed matrix membranes (MMMs). Inorganic zeolite materials distributed in the organic polymer matrix enhance the separation performance of the membranes well beyond the intrinsic properties of the polymer matrix. This concept combines the advantages of both components: high selectivity of zeolite molecular sieve, and mechanical integrity as well as economical processability of the polymeric materials. In this paper gas permeation mechanism through polymeric and zeolitic membranes, material selection for MMMs and their interaction with each other were reviewed. Also, interfacial morphology between zeolite and polymer in MMMs and modification methods of this interfacial region were discussed. In addition, the effect of different parameters such as zeolite loading, zeolite pore size, zeolite particle size, etc. on gas permeation tests through MMMs was critically reviewed.