Health Affairs

Abstract This article describes the manner in which a novel composite compound was synthesized using a novel method and optimized using a poly(4-[pyrrol-1-yl methyl]benzoic acid) (PPy-b) polymer and very little amount of metallic silver microparticles. The deposition of the polymer film on a fluorine-doped tin oxide (FTO) substrate surface was performed by electrochemical oxidation of the monomer in acetonitrile medium at an imposed potential. The incorporation of silver microparticles was carried out by immersing the modified electrode in a solution of silver nitrate to complex the Ag+ ions with the carboxylic group (COOH) present in the backbone of the polymer, followed by an electrochemical reduction of the complex to precipitate the silver in the form of metallic microparticles in the polymer film. Different characterization techniques (cyclic voltammetry, electrochemical impedance spectroscopy, and surface analysis techniques) were used to optimize the prepared material. Despite the very small quantity of silver (a few micrograms), inserted into the polymer film, the composite material thus obtained had good electrical, optical, and catalytic properties.

Abstract Herein, epoxy coatings modified with milled aluminum (Al) were tested for their mechanical strength and corrosion resistance. First, milling was performed on the as-received Al powder for 70 h. The obtained powder postmilling was added to DGEBA-type epoxy resin and cured with an amine-based D450 hardener. The milled Al powder was added in varying weight percentages (1, 2, and 3%). Different types of panels were coated using an automatic film applicator to obtain controlled film thickness and left for curing. Morphological characterization was done using field emission scanning electron microscopy and X-ray diffraction. Thermal stability of the coatings was evaluated using thermogravimetric analysis. Mechanical properties were measured using conventional testing techniques as well as nanoindentation. The analysis results suggest that milling of Al alters the structure of powder postmilling. The milling operations also have an effect on the mechanical and anticorrosion properties of the materials. The results obtained for the prepared modified coating suggest that addition of 2 wt% in the epoxy resulted in balanced mechanical and anticorrosion properties.

Abstract Herein, based on the strengthening mechanism and aging mechanism of 9% Cr steel, changes in the microstructure and mechanical properties during long-term high-temperature service are analyzed. The limitations of current microstructure observation in the aging rating process and the defects of the aging evaluation system are expounded. It is proposed that the aging evaluation of 9% Cr martensitic heat-resistant steel can distinguish between the abnormal microstructure and the aging phenomenon occurring during long-term operation, and the combination of higher resolution microscopy observation such as laser confocal scanning microscopy with mechanical property tests could provide a comprehensive judgement.

Abstract The high-value utilization of recycled powder (RP), primarily derived from construction and demolition waste, has been limited due to its low reactivity. In this study, the effect of RP subjected to three types of inorganic alkalis (sodium hydroxide, sodium carbonate, and calcium hydroxide [CH]), two alkanolamines (diethanolisopropanolamine [DEIPA] and triisopropanolamine [TIPA]), elevated temperatures, and their combined activation on the technical properties of RP grouts was analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the development of the mineral composition and micromorphology of the grout pastes. The results indicated that alkali and thermal activation of RP had negative effects, while combined activation improved the fluidity of the grout pastes. The compressive strength of alkali-activated groups was slightly enhanced at 1 day but significantly decreased at 28 days. In contrast, the compressive strength of grouts activated with CH, alkanolamines, and thermal treatment was found to be improved at all ages. The compressive strength of the grout paste containing 40% combined-activated RP was measured at 43.1, 73.3, and 95.7 MPa at 1, 3, and 28 days, respectively, which represented increases of 20.4, 19.6, and 17.7%, respectively, compared to the non-activated grout. Combined activation demonstrated the most improvement in the microstructural density of the grouts when compared to the single-activation mode.

Abstract This study aimed to enhance the wear resistance of the AA8090 material. Nanoparticle-reinforced AA8090 metal matrix composites were manufactured using the conventional stir casting process. Totally, three types of composites were fabricated by varying the cerium oxide (CeO2) nanoparticle content. The different materials prepared were AA8090, AA8090/1.5 wt% CeO2, AA8090/3 wt% CeO2, and AA8090/4.5 wt% CeO2. Properties like microhardness, tensile strength, wear rate, and coefficient of friction of the developed composites were determined. The results showed that the inclusion of CeO2 nanoparticles improved the different properties of the AA8090 material. An optimum level of 3 wt% CeO2 in AA8090 showed better performance. Furthermore, the AA8090/3 wt% CeO2 composite exhibited a maximum hardness and tensile strength of 158 HV and 546 MPa, respectively, which was 18 and 20% higher than those of AA8090. Furthermore, the same composite displayed a slightest wear rate (0.045 × 10−3 mm3/m) and coefficient of friction (0.2). Hence, it is concluded from this research that the AA8090/3 wt% CeO2 could be a suitable material for aero, military, and marine applications as it showed a good performance.

Abstract Spinal cord injuries (SCIs) continue to pose a significant challenge in regenerative medicine and neuroscience, inflicting severe consequences on affected individuals. This study aims to evaluate the therapeutic efficacy of sports medicine along with gelatin electrospun scaffolds loaded with green tea extract (GTE) and seeded with bone marrow-derived mesenchymal stem cells (BM-MSCs) for SCI repair in a rat model. The electrospun scaffolds were fabricated from GTE-loaded polycaprolactone/gelatin polymeric solution. BM-MSCs were then seeded onto the scaffolds, which were implanted into rat models of SCI. The animals then underwent daily treadmill exercise. Histological analysis and functional assessments were conducted to evaluate the extent of spinal cord repair and functional recovery. The study showed that the hybrid treatment strategy augmented SCI “repair” and restored tissue function. Enzyme-linked immunosorbent assay results showed that our method upregulated tissue expression levels of brain-derived neurotrophic factor and nerve growth factor and decreased the tissue expression levels of tumor necrosis factor-alpha and interleukin-1 beta.

Abstract This work concerns the analysis of the application of the nitriding process to forging dies used for the production of automative forgings on a hammer. The subject technological process concerns the production of forgings of a ring section made of AISI 304 stainless steel. The subject process is carried out on a LASCO HOU-160 forging hammer with a power of 16 kJ, in two operations, on the blocking impression and then on the finishing impression. In order to assess the influence of the nitriding process on the durability of tools, operational tests are carried out for three sets of tools after thermochemical treatment under real industrial conditions and then confronted with the results for standard tools (without a nitrided layer). The comprehensive studies carried out, including macroscopic analyses combined with scanning, numerical modeling, and microstructural tests for both standard tools and after nitriding, show a decrease in the durability of forging tools as a result of the use of nitriding in relation to the previous technology. It should also be considered that the process was carried out on hammers, for very thin forgings. Then, there are very high dynamic loads, which can lead to cracking of hard nitriding layers.

Abstract This study investigated the impact of adding lead (Pb) and molybdenum disulfide (MoS2) to copper–graphite (Cu–Gr) composites used in electric motors. The composites were produced by mechanical alloying (MA). The mixture was then poured and compressed with varying amounts of Pb and MoS2. Differential thermal analysis was used to determine the sintering temperature of the samples. Further tests were conducted to assess the samples’ wear resistance, density, hardness, and porosity. The effects of the additives of these factors were examined, and the output current of the samples was measured. Scanning electron microscopy was also used to analyze the morphology of the Gr plates coated with Cu, Pb, and MoS2. The results indicated that adding Pb and MoS2 increased the density of the sintered samples and their Vickers hardness. Meanwhile, porosity decreased with increased concentrations of Pb and MoS2. Additionally, MoS2 was found to improve wear resistance via a pin-on-disk test.

Abstract Geopolymer concrete (GPC) can be substituted for Portland cement concrete because it is cement-free, environmentally friendly, cost-effective, durable, and highly performing. It is an excellent solution for sustainable growth in the building sector. The curing and mixing periods are essential for making homogeneous, compact, or highly dense concrete. The primary aim of this research was to analyze the effect of mixing and curing periods on the physical, chemical, and mechanical characteristics of GPC. The experimental analysis investigated its physical properties, chemical properties, and mechanical properties. After the experimental investigation, it was concluded that the workability and setting time decreased with the increase in mixing time. Regarding chemical properties, the density of GPC specimens reduced as the curing time increased, and it increased as the mixing time increased, although drying shrinkage decreased under both scenarios. For mechanical properties, the compressive strength, splitting tensile strength, flexural strength, and elastic modulus initially increased with the increase in mixing and curing time up to 24 h but decreased significantly afterward. In the analysis of the non-destructive test, the rebound strength and ultrasonic pulse velocity exhibited the same pattern as the destructive mechanical characteristics, with the 24- h curing period achieving the highest point among all other curing times. This research found that the optimum oven curing period for GPC was 24 h for gaining mechanical and chemical properties because the mixing and curing periods play an essential role in gaining strength.

Abstract In this study, the corrosion resistance of four different hardfacing layers in a 3.5% NaCl solution was tested. Using 316L steel as a reference material, NiCrBSi, NiCrBSi + 35 wt% WC, and NiCrCuMo were deposited onto a structural steel S235JR substrate using the plasma powder transferred arc technology and prepared samples in a disc form for testing. The purpose of this investigation was to propose an alternative material to the commonly known anti-corrosion protection product of 316L steel simultaneously with better wear resistance. Its corrosion damage mechanism was assessed based on electrochemical examination and is related to changes in the microstructure of the sample surface investigated by using a potentiostat and a scanning electron microscope. Polarization tests were carried out, which confirmed that all proposed overlayers provide effective anti-corrosion protection. For all samples, the corrosion current density did not exceed 0.3 µA/cm2, and the corrosion potential was not less than −290.9 mV, which were considered positive results.

Abstract Switching to alternative energy sources is imperative at present. Solar energy is known as one of the Earth’s most cost-effective and sustainable sources of energy. Tin sulphide (SnS) is a commonly studied photovoltaic material, along with other materials such as metal chalcogenides, chalcopyrites, and perovskites. SnS possesses an appropriate band gap and an absorption coefficient within the required range, rendering it a viable material for solar cell applications. Researchers are attracted to SnS-based solar cells because of their easy-to-adjust structural parameters, plentiful availability, uncomplicated composition, and excellent mobility. This article models several characteristics of SnS-based solar cells using the SCAPS-1D simulation program. The NiO/SnS/TiO2/ITO solar cell construction may attain an efficiency of 24.0% with optimum configurations. The key criteria to be considered by researchers are the conduction band offset, the work function of the back contacts, and the radiative recombination factor (coefficient). The conduction band density of states is the least affected by the cell’s efficiency compared to other simulated metrics. This research may provide valuable information on the potential of SnS-based solar cells to achieve high efficiency.

Abstract Additive manufacturing (AM), i.e., 3D printing, has seen significant growth in recent years in all industries due to its potential advantages, requiring the polymers that are adapted as for melt flow index (MFI) to this use to have adequate tensile strength as well. Hence, in this work, a novel ligno-cellulosic fiber from Cryptostegia grandiflora (CG) and polylactic acid (PLA) were blended to obtain a filament for AM using a twin screw extruder. To determine the filament’s suitability for the 3D printing process, MFI and thermal degradation were examined. In order to identify the distribution and the effect of CG fiber (CGF) filler on the matrix, the filaments were examined using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). CGF powder distribution was observed in the microstructure of the CGF/PLA composite filament. Due to the high compatibility between PLA and CGF, their blending slightly increased the degradation temperature, though did not lead to any crystallinity loss, and the CGF/PLA filament showed 12.5% better tensile characteristics than the pure PLA filament. Based on their performance, the CGF may represent a suitable and compatible filler to improve the properties of the PLA filament for 3D printing applications.

Abstract To enhance the high-value utilization of industrial wastewater, this study used ammonium sulfate wastewater discharged from a rare earth plant as a raw material for producing anhydrous calcium sulfate whiskers (CSWs) through a hydrothermal method. Subsequently, the whiskers underwent modification using a C18H36O2–titanate coupling agent. The modification mechanism of CSW was investigated by comparing the surface contact angle before and after modification, along with characterization and analysis involving X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric-differential thermal analysis, and X-ray photoelectron spectroscopy. Finally, composite-modified calcium sulfate whiskers (CMCSWs) were incorporated into polyvinyl chloride (PVC) composites, and their mechanical properties were evaluated. The results indicated that at a modifier dosage of 15%, a modification time of 25 min, a modification temperature of 80°C, a stirring speed of 400 rpm, a drying temperature of 100°C, and a C18H36O2-to-titanate coupling agent compound ratio of 1:2, the contact angle reached 124.45°, and a nanoscale hydrophobic layer with a thickness of 15.63 nm was formed on the surface. Regarding PVC reinforcement, the tensile strength and elongation at the break of PVC composite with 15 parts of CMCSW added increased by 73 and 262%, respectively, compared to the material without CSW. This CSW serves as an innovative reinforcing agent for PVC composites. The study developed modified CSW with high hydrophobicity, offering theoretical insights for effectively modifying fiber-type whiskers and their reinforcement in PVC applications.

Abstract Aerosol jet printing (AJP) is a contactless direct-write approach aimed at the production of fine features on a wide range of substrates. The technology has been explored for a variety of applications, including active and passive electronic components, actuators, sensors, and a variety of selective chemical and biological responses. However, the quality of conductive traces printed with nanoparticle inks using AJP can be affected by several factors, including carrier and sheath gas flow rate, ink properties, and substrate material properties. A typical defect present in the prints, such as non-uniform metal particle distribution, solvent local concentration, porosity, delamination, and bubbles, can be reduced by additional ultrasonic post-printing treatment. Therefore, the article investigates the influence of the self-designed sonotrode tool on the quality of conductive traces printed with nanoparticle inks using AJP. An ultrasonic head was fixed in a tandem position behind a printing nozzle at a distance equal to the node of ultrasonic waves. In this article, it was found that ultrasound has a positive effect on the quality of printed traces by improving degassing with simultaneous uniform particle distribution. As a result, the surface open porosity obtained for printed and ultrasonically treated traces was decreased almost seven times from 17.2 to 2.7%, respectively. An improved surface and structural morphology increased electrical resistivity in the prints from 6.85 to 4.57 µΩ cm. The analysis included quantifying the macroscale geometry, electrical properties, and micromorphological characteristics of the traces. The results of this article suggest that the application of ultrasonic-assisted aerosol jet printing with a proper tool improves the quality of AJP prints.