B- and N-doped carbon coupled with different morphologies of MoS2 for hydrogen evolution reaction

Journal of Applied Electrochemistry - In the present work, four different morphologies of MoS2 structure, including bulk, flake, plate, and flower-shaped, were prepared and used to prepare Vulcan...     

The effect of mordant salts on antibacterial activity of wool fabric dyed with pomegranate and walnut shell extracts

Natural dyes have attracted increasing worldwide attention because of the carcinogenicity and environmental effects of synthetic dyes. In this study, wool fabric was treated with tannin‐rich extracts of Punica granatum peel and walnut shell in combination with some mordants. The effect of various mordants on the colorimetric and antibacterial properties of wool fabrics was investigated. The results showed that pretreatment with metallic mordants substantially improved the dyeing and fastness properties of wool fabrics. The extracts of Punica granatum peel and walnut shell showed a significant antibacterial activity at 5% concentration. In addition, antibacterial activity was dramatically enhanced using metallic salts. The antibacterial activity of samples dyed with natural dyes and without any mordant was not good, while the mordanted samples with copper, aluminum and tin salts obtained considerable antimicrobial properties following lightening and washing fastness. The extracts of Punica granatum peel and walnut shell can be considered as viable alternatives instead of artificial antibacterial agents for hospital textiles as well as an effective anti‐odour agent for sports and household textiles.     

Ionic liquid ultrasound assisted dispersive liquid-liquid microextraction method for preconcentration of trace amounts of rhodium prior to flame atomic absorption spectrometry determination

In this article, we consider ionic liquid based ultrasound-assisted dispersive liquid-liquid microextraction of trace amounts of rhodium from aqueous samples and show that this is a fast and reliable sample pre-treatment for the determination of rhodium ions by flame atomic absorption spectrometry. The Rh(III) was transferred into its complex with 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol as a chelating agent, and an ultrasonic bath with the ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide at room temperature was used to extract the analyte. The centrifuged rhodium complex was then enriched in the form of ionic liquid droplets and prior to its analysis by flame atomic absorption spectrometry, 300 μL ethanol was added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh(III) was optimized. Under optimum conditions, the calibration graph was linear in the range of 4.0-500.0 ng mL(-1), the detection limit was 0.37 ng mL(-1) (3S(b)/m, n = 7) and the relative standard deviation was ±1.63% (n = 7, C = 200 ng mL(-1)). The results show that ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction, combined with flame atomic absorption spectrometry, is a rapid, simple, sensitive and efficient analytical method for the separation and determination of trace amounts of Rh(III) ions with minimum organic solvent consumption.     

The electroless plating of Cu-Ni-P alloy onto cotton fabrics

The objective of this study is to apply the electroless plating of Cu-Ni-P alloy on cotton fabrics to the preparation of conductive fabrics. The alloy composed of infinit small amount of nickel and phosphorus particle originated from sodium hypophosphite and nickel sulphate respectively as reducing agent and hypophosphite oxidation accelerator. Electroless plating of Cu-Ni-P alloy on cotton fabrics and effect of plating on the physical and mechanical properties of alloy coated fabrics as well as electromagnetic interference (EMI) shielding effectiveness were reported in detail. In this research highly washing and abrasion durable conductive fabrics obtained with supreme shielding effectiveness.     

Sulfonated Ordered Nanoporous Carbon (CMK-5-SO<Subscript>3</Subscript>H) as an Efficient and Highly Recyclable Catalyst for the Silylation of Alcohols and Phenols with Hexamethyldisilazane (HMDS)

Abstract  

An environmentally friendly catalytic system for trimethylsilylation of alcohols and phenols with hexamethyldisilazane can be successfully carried out for the first time over sulfonated mesoporous carbon catalyst (CMK-5-SO₃H) in dichloromethane at ambient temperature and excellent conversions were obtained. Furthermore, the catalyst displays high activity and thermal stability (to 200 °C) and it can be reused repeatedly for at least 25 cycles without any evidence of loss of activity, confirming the stability of covalent bonding of acidic centers.     

Characterization of the complex permittivity of brain tissues up to 50 GHz utilizing a two-port microstrip test fixture

Broad-band complex-permittivity values of biological tissues above 20 GHz obtained from direct measurements have not been reported in the literature. This paper presents for the first time the measurement results of complex permittivity of brain grey and white matters from 15 to 50 GHz utilizing a two-port microstrip test fixture. Test fixture S-parameters are simulated employing the finite-element method. To apply the data obtained from the simulation in complex-permittivity extraction, an efficient procedure, using the linear least square technique, is introduced to fit the modeling results to a rational function of complex permittivity, which is similar to the transfer function for a linear system. This fitting procedure is computationally more efficient than the previously developed fitting methods. Measurements are performed on slices of brain sample using a calibrated network analyzer utilizing custom designed through-reflect-line (TRL) calibration standards. The measurements are corrected for the residual errors observed in the measurement results due to the lack of performance repeatability of coaxial-to-microstrip launchers utilized in the TRL calibration standards. Finally, the measured results for brain matters are fitted to a single term Cole-Cole relation representing the dispersion characteristics of white and grey matters up to 50 GHz.     

Synthesis and characterisation of LiB3 O5 nanophosphor as a TL dosimeter

In this work, lithium triborate (LiB₃ O₅) nanophosphor was synthesised by precipitation assisted high‐temperature solid‐state method followed by heating at different sintering temperatures. Then, its crystal structure and morphology were fully characterised. LiB₃ O₅ was doped with different concentrations of different dopants. To determine the thermoluminescence (TL) properties and structural specifications of doped lithium triborate, the sample was irradiated by photons and then, its TL glow curve was obtained using a TL dosimeter‐reader system. To study the effect of heating rate (HR) on TL characterisation of this nanophosphor, TL measurements were done at different HRs. The results showed that, sintering temperature can affect the morphology and structural properties of lithium triborate and consequently its TL intensity. The findings also showed that the LiB₃ O₅ :Al nanophosphor with the dopant concentration of 2 wt.% has the highest sensitivity and the best peak position among the studied activators. The results of the HR method showed that this method may be provided accurate calculations of the physical parameters of the TL process. These results may be helpful in the development of tissue equivalent TL nanocrystalline detectors usable in medical and personnel dosimetry.Inspec keywords: thermoluminescent dosimeters, sintering, phosphors, crystal structure, dosimetry, thermoluminescence, lithium compounds, nanostructured materials, nanofabrication, aluminiumOther keywords: high‐temperature solid‐state method, crystal structure, morphology, thermoluminescence properties, structural specifications, doped lithium triborate, TL glow curve, TL dosimeter‐reader system, heating rate, TL characterisation, TL measurements, sintering temperature, structural properties, TL intensity, nanophosphor, dopant concentration, HR method, TL process, tissue equivalent TL nanocrystalline detectors, LiB₃ O₅ :Al     

Optimization of proteases pretreatment on natural dyeing of wool using response surface methodology

Natural dyes and enzymes have attracted a lot of attention due to their non-hazardous nature. In this research, wool fabrics were pretreated with the commercial protease at different concentrations over various times. The dyeing process was then carried out on the treated fabrics with the commercial madder and cochineal. Also, the central composite design analysis was used to design the relation between dye exhaustion and some properties of dyed wool including tensile strength, alkaline solubility, water drop absorption, and weight loss based on Design of Expert software. The response surface methodology was also applied to find the optimum conditions for the wool fabric pretreatment. The scanning electron microscopy was employed to indicate the influences of proteases on the fabric surface. The optimized proteases pretreatment on the wool surfaces has considerably improved the absorption of madder and cochineal and minimized the damage to appropriate physical properties. The adsorption kinetic of madder and cochineal on enzymatic wool fiber was fitted with a pseudo-second-order model. The rate of dyeing at different temperatures, as well as the values of standard affinity, entropy, and enthalpy, was calculated. The activation energy of dyeing with madder and cochineal at different temperatures are 23.79 and 30.96 kJ/mol, respectively, considering that these values are in the typical activation energy for physisorption. It was also found that wash, light, wet and dry rub fastness properties of the samples dyed along with protease have not changed significantly. This can be easily scaled up in the industry as a simple method using the commercial materials.