Study of mechanical properties of indium-based solder alloys for cryogenic applications

Purpose This study aims to develop indium-based solders for cryogenic applications. Design/methodology/approach This paper aims to investigate mechanical properties of indium-based solder formulations at room temperature (RT, 27 °C) as well as at cryogenic temperature (CT, −196 °C) and subsequently to find out their suitability for cryogenic applications. After developing these alloys, mechanical properties such as tensile and impact strength were measured as per American Society for Testing and Materials standards at RT and at CT. Charpy impact test results were used to find out ductile to brittle transition temperature (DBTT). These properties were also evaluated after thermal cycling (TC) to find out effect of thermal stress. Scanning electron microscope analysis was performed to understand fracture mechanism. Results indicate that amongst the solder alloys that have been studied in this work, In-34Bi solder alloy has the best all-round mechanical properties at RT, CT and after TC. Findings It can be concluded from the results of this work that In-34Bi solder alloy has best all-round mechanical properties at RT, CT and after TC and therefore is the most appropriate solder alloy amongst the alloys that have been studied in this work for cryogenic applications Originality/value DBTT of indium-based solder alloys has not been found out in the work done so far in this category. DBTT is necessary to decide safe working temperature range of the alloy. Also the effect of TC, which is one of the major reasons of failure, was not studied so far. These parameters are studied in this work.

An efficient composite membrane to improve the performance of PEM reversible fuel cells

The aim of this study is to develop composite Nafion/GO membranes, varying GO loading, to be used in a Unitized reversible fuel cell comparing its performance with the baseline Nafion. Water uptake, ion exchange capacity (IEC), tensile strength, and SEM (scanning electron microscope) analysis are discussed. The SEM analysis revealed how the GO is homogeneously disposed into the Nafion matrix. The addition of GO improves the membrane tensile strength while reducing the elongation ratio. Water uptake, IEC enhance with the increasing of GO content. Regarding fuel cell mode, the performance is analysed using a polarization curve on a MEA with an effective area of 9 cm2. The composite membrane demonstrated higher mechanical strength, enhanced water uptake so higher performance in fuel cell mode. Despite the power absorbed from the electrolysis is higher when using a composite membrane, the beneficial effect in FC mode resulted in a slightly higher round trip efficiency. The GO-Nafion membrane was not able to maintain its performance with increasing the operating time, so potentially leading to a lower lifetime than the Nafion bare.

The Impact of Artificial Marble Wastes on Heat Deflection Temperature, Crystallization, and Impact Properties of Polybutylene Terephthalate

As artificial marble is abundant and widely used in residential and commercial fields, the resource utilization of artificial marble wastes (AMWs) has become extremely important in order to protect the environment. In this paper, polybutylene terephthalate/artificial marble wastes (PBT/AMWs) composites were prepared by melt blending to maximize resource utilization and increase PBT performance. The research results showed that the filling of AMWs was beneficial to the improvement of PBT-related performance. X-ray diffraction analysis results indicated that after filling AMWs into the PBT matrix, the crystal structure of PBT was not changed. Heat deflection temperature (HDT) analysis results indicated that the HDT of PBT composites with 20 wt% AMWs reached 66.68 °C, which was 9.12 °C higher than that of neat PBT. Differential scanning calorimetry analysis results showed that heterogeneous nucleation could be well achieved when the filling content was 15 wt%; impact and scanning electron microscope analysis results showed that due to the partial core-shell structure of the AMWs, the impact strength of PBT was significantly improved after filling. When the filling amount was 20 wt%, the impact strength of the PBT composites reached 23.20 kJ/m2, which was 17.94 kJ/m2 higher than that of neat PBT. This research will not only provide new insights into the efficient and high-value utilization of AMWs, but also provide a good reference for improved applications of other polymers.

Poly(styrene-co-butadiene)/Maghnia-Organo-Montmorillonite Clay Nanocomposite. Preparation, Properties and Application as Membrane in the Separation of Methanol/Toluene Azeotropic Mixture by Pervaporation

In order to improve the thermal and mechanical properties of poly(styrene-co-butadiene) (SBR) to use it as a pervaporation membrane in the separation of the azeotropic mixture toluene/methanol, poly(styrene-co-butadiene) crosslinked Maghnia-organo-montmonrillonite (CSBR/OMMT), a nanocomposite of different compositions was first prepared by a solvent casting method. SBR was crosslinked in situ in the presence of OMMT nanoparticles by an efficient vulcanization technique using sulfur as a crosslinking agent and zinc diethyldithiocarbamate as a catalyst. The structure and morphology of the hybrid materials obtained were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope analysis. The thermal properties of these hybrid materials were studied by differential scanning calorimetry and thermogravimetric analysis/thermal differential analysis. The mechanical properties were studied by strength measurements. The results obtained occurred when the OMMT was incorporated in the CSBR matrix; a significant increase in the glass transition temperature of the SBR was observed which passed from −27 °C for virgin SBR to −21.5 °C for that containing 12 wt% of OMMT. The addition of OMMT nanoparticles to CSBR also improved the mechanical properties of this copolymer. When the OMMT content in the CSBR varied from 0 to 15% by weight, the tensile strength, the elongation at the nose and the modulus at 100% elongation increased from 3.45 to 6.25 MPa, from 162, 17 to 347.20% and 1.75 to 3.0 MPa, respectively. The results of pervaporation revealed that when the OMMT content varied between 3% and 12%, a significant increase in the total flux, the separation factor and the separation index by pervaporation increased from 260.67 to g m−2 h−1, 0.31 to 1.43, and 0.47 to 113.81 g m−2 h−1, respectively.

Effect of antioxidants agents on Dentinal Tubular Penetration of EndoREZ sealer on sodium hypochlorite-treated root canal dentin: A Scanning electron microscopic study v1

According to ISO, the canals were enlarged to a size 30, 6% taper with ProTaper gold (Dentsply Sirona, Ballaigues, Switzerland) by crown down technique (Singh et al., 2015).Irrigation was performed with Saline and 17% EDTA in Group I. After biomechanical preparation, groups II, III, IV, and V were irrigated with 5 mL-Sodium hypochlorite (5.25%) and 5 mL-EDTA (17%) for 1 minute. Irrigation was done on Groups III, IV, and V for an additional 10 minutes with 10% Ellagic acid, 5% Lycopene extract, and 5% Grape Seed Extract, respectively. After irrigation, the root canals were dried. The EndoREZ (Ultradent Products, Inc., South Jordan, Utah, USA) was used in the canals using a 25-size spreader (Mani Inc., Tochigi, Japan), followed by warm vertical condensation. Scanning Electron Microscope Analysis: The specimens were longitudinally sectioned. Then samples were immersed in 17% EDTA solution for 10 minutes, immersed in 5.25 percent sodium hypochlorite for 10 minutes, and lastly washed entirely with water to remove and smear the layer. Carbon sputtering was performed in the middle and apical thirds of the root canal to aid SEM (500x magnification) evaluation.

Strength Characteristics of Alkali-Activated Slag Mortars with the Addition of PET Flakes

The production of ordinary Portland cement is associated with significant CO2 emissions. To limit these emissions, new binders are needed that can be efficiently substituted for cement. Alkali-activated slag composites are one such possible binder solution. The research programme presented herein focused on the creation of alkali-activated slag composites with the addition of PET flakes as a partial substitute (5%) for natural aggregate. Such composites have a significantly lower impact in terms of CO2 emissions in comparison to ordinary concrete. The created composites were differentiated by the amount of activator (10 and 20 wt.%) and curing temperature (from 20 to 80 °C). Their mechanical properties were tested, and a scanning electron microscope analysis was conducted. Compressive and flexural strengths ranging from 29.3 to 68.4 MPa and from 3.5 to 6.1 MPa, respectively, were achieved. The mechanical test results confirmed that a higher amount of activator improved the mechanical properties. However, the influence of the PET particles on the mechanical properties and microstructure varied with the curing temperature and amount of activator. Areas that require further research were identified.

Preparation of Sensitivity Test Antibiotic Discs Using Some Nanomaterials to Detect Resistance of Pseudomonas Aergenosa to Some Antibiotics

This study was conducted to synthesize bentonite nanoparticles and load them on different antibiotics to increase the effectiveness of the antibiotics or treat the resistance of Pseudomonas aeruginosa to some types of antibiotics in the laboratory. The biosynthesized bentonite nanoparticles were characterized by spectrophotometry and scanning electron microscopy. Their antibacterial activity against Pseudomonas aeruginosa was determined by the (muller-hinton) method of diffusion in plates compared with antibiotics using different concentrations of each ranging from 12.5-200 µg/ml. The results of this study showed that it is possible to synthesize bentonite nanoparticles in an easy and environmentally friendly manner, and the maximum absorption spectra of these nanoparticles were at 420 and 430 nm using a spectrophotometer. The scanning electron microscope analysis also showed that the average diameter of these particles was 26 nanometers, in addition to their high activity against bacteria.

Removal of Congo red from aqueous solution in single and binary mixture systems using Argan nutshell wood

Purpose Argan nutshell wood (ANW) has been used in this study as an agricultural solid waste to remove Congo red (CR) from an aqueous solution in single and mixture binary in the presence of methylene blue (MB) or crystal violet (CV). Design/methodology/approach The ANW was characterized by Fourier transform infrared and scanning electron microscope analysis. The effect of ANW dose (8–40 gL−1), contact time (0–180 min), pH of the solution (4–11) and CR dye concentration (100–500 mgL−1) on CR adsorption was studied in batch mode and evaluated by kinetic and isotherm models in a single system. In the binary system, the CR removal was studied from a CR + MB and CR + CV mixture with different percentages of dyes, ranging from 0% to 100%. Findings The pseudo-second-order and the Langmuir models could best describe the CR sorption onto ANW in a single system. In addition, in the case of the binary system, there is the appearance of a synergistic phenomenon between the CR and the other cationic dyes and the CR adsorption capacity increased until 12.24 mg g-1 and 12.06 mg g-1 in the presence of the MB and CV in the mixture, respectively. Practical implications This study demonstrated that ANW prepared can be suggested as an excellent potential adsorbent to remove dyes from wastewaters from single and mixture systems. Originality/value This study is original.

Intracellular S. aureus in Osteoblasts in a Clinical Sample from a Patient with Chronic Osteomyelitis—A Case Report

The pathophysiological role of intracellular bacteria in osteomyelitis is still a matter of debate. Here, we demonstrate for the first time the presence of Staphylococcus aureus internalized into osteoblasts in human tissue samples of a case with a chronic osteomyelitis using ultrastructural transmission electron microscope analysis.

Manufacturing of Al2O3/Ni/Ti Composites Enhanced by Intermetallic Phases

In this study, ceramic–metal composites in the Al2O3/Ti/Ni system were fabricated using the slip casting method. Two series of composites with 15 vol.% metal content and different solid phase contents were obtained and examined. A proper fabrication process allows obtaining composites enhanced by intermetallic phases. The microstructure of the base powders, slurries, and sintered composites was analyzed by scanning electron microscope. Analysis of the sedimentation tendency of slurries was carried out. The phase composition of the sintered samples was examined by X-ray diffraction analysis. A monotonic compression test was used to investigate the mechanical properties of the composites. A fractography investigation was also carried out. The research conducted revealed that the slip casting method allows the obtaining of composites enhanced by intermetallic phases (TiNi, Ni3Ti). The results show the correlation between solid-phase content, microstructure, and mechanical properties of the composites.