International Journal of Mechanical and Materials Engineering最新文献

Perovskite materials have emerged as promising candidates for next-generation photovoltaic devices due to their unique optoelectronic properties. In this study, we investigate the incorporation of bromine into cesium lead mixed iodide and bromide perovskites (CsPbI_3(1-x)Br_3x) to enhance their performance. By depositing films with varying bromine concentrations (x = 0, 0.25, 0.5, 0.75), we employ a combination of structural and optical characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy, and photoluminescence. Our analysis reveals that introducing bromine leads to structural modifications, influencing the perovskite films’ optical properties and energy gap. Specifically, we observe semiconductor behavior with a tunable energy gap controlled by the intercalation of bromine atoms into the CsPbI₃ lattice. Furthermore, heat treatment induces phase transitions in the perovskite films, affecting their optical responses and crystalline quality. SCAPS-1D simulations confirm the improved stability and efficiency of bromine-doped CsPbI₃ films compared to undoped counterparts. Our findings demonstrate that bromine incorporation facilitates the formation of highly crystalline perovskite films with reduced trap defects and enhanced carrier transport properties. These results underscore the potential of bromine-doped CsPbI₃ perovskites as promising materials for high-performance photovoltaic applications, paving the way for further optimization and device integration.

This work explores environmentally conscious machining practices for AISI4140 steel through Taguchi analysis. The study employs a design of experiments (DOE) approach, focusing on cutting speed, depth of cut, and coolant type as parameters. Taguchi’s L9 orthogonal array facilitates systematic experimentation, and the results are analyzed using MINITAB 17 software. Signal-to-noise ratios (SNR) are utilized to establish optimum operating conditions, evaluate individual parameter influences, and create linear regression models. The experiments reveal neem oil with graphene coolant as an eco-friendly solution, addressing health and environmental concerns. Main effects plots visually represent the impact of parameters on machining quality. Additionally, regression and artificial neural network (ANN) models are compared for surface roughness prediction, with ANN showing superior performance. The findings advocate for optimized cutting conditions, emphasizing material conservation, enhanced productivity, and eco-friendly practices in AISI4140 steel machining. This research contributes valuable insights for industries seeking sustainable machining solutions.

This paper presents a new method for detecting malathion pesticides using a modified screen-printed electrode (SPE) with a fluorescence quenching technique. The manganese-based MOF was synthesized using the solvothermal method. The synthesized MOFs were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The material’s electrocatalytic properties were assessed via electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Within the concentration range of 0.89 µM to 5.95 µM, the material’s response to malathion was analyzed with square wave voltammetry (SWV), giving rise to a detection limit of 39.097 nM. Fluorescence quenching studies have been carried out between 0.039 and 0.56 µM, with a lower detection limit of 62.03 nM. A sensor with good anti-interference properties was tested for selectivity and practicability in detecting malathion in real samples, proving its potential use in this area.

Decellularized amnion (dAM)-derived hydrogels have been extensively exploited for versatile medical and therapeutical applications, particularly for soft tissue engineering of skin, vascular graft, and endometrium. In contrast to polyacrylamide-based hydrogels, which have been extensively employed as a 3D cell culture platform, the cell response of dAM hydrogel is yet to be understood. In this study, we have prepared hydrogels containing different concentrations of dAM and systematically investigated their microstructural features, gelation kinetics, and rheological properties. The results show that dAM hydrogels possess a network of fibers with an average diameter of 56 ± 5 nm at 1% dAM, which increases to 110 ± 14 nm at 3% dAM. The enhanced intermolecular crosslinking between the microfibrillar units increases the gelation rate in the growth phase of the self-assembly process. Moreover, increasing the concentration of dAM in the hydrogel formulation (from 1 to 3%w/v) enhances the dynamic mechanical moduli of the derived hydrogels by about two orders of magnitude (from 41.8 ± 2.5 to 896.2 ± 72.3 Pa). It is shown that the variation in the hydrogel stiffness significantly affects the morphology of dermal fibroblast cells cultured in the hydrogels. It is shown that the hydrogels containing up to 2%w/v dAM provide a suitable microenvironment for embedded fibroblast cells with spindle-like morphology. Nevertheless, at the higher concentration, an adverse effect on the proliferation and morphology of fibroblast cells is noticed due to stiffness-induced phenotype transformation of cells. Concentration-modulated properties of dAM hydrogels offer an in vitro platform to study cell-related responses, disease modeling, and drug studies.

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This study explores how expanded thermoplastic polyurethane (ETPU) responds to temperature and compression at various temperatures. Dynamic mechanical thermal analysis (DMTA) was used to understand the temperature influence at small deformations. To investigate the deformation behavior at different compression stages we employed in-situ CT measurements and 3D strain mapping. Through quasi-static compression tests at temperatures from − 50 to 120 °C, we determined the influence of temperature on compression modulus, elastic stress, stress at 50% deformation, densification, and energy absorption. Remarkably, ETPU demonstrates robust recovery after compression, particularly within the − 50 to 60 °C temperature range. Subsequent compression tests show consistent or even slightly increased compression properties, such as a 10% increase in energy absorption for samples previously tested at − 40 °C, indicating that ETPU can withstand prior exposure to different temperatures.

To ascertain upon the ideal configuration of physico-mechanical qualities, efficient processing techniques, and network stability of the prepared bio-composite films in real-world applications, the polymeric materials shall be subjected to a careful manipulation. Such bio-composite films have outstanding combinations of biocompatibility and toxicity-associated safety qualities. Such research interventions will be beneficial for the packaging, pharmaceutical, and biomedical industries that wish to target and adopt them for commercial applications. In this article, three alternate organic acids, i.e., citric acid (CA), tartaric acid (TA), and malic acid (MA), are blended separately into polyvinyl alcohol (PVA)-starch (St)-glycerol (Gl) composite films and for the targeted purpose of enhanced crosslinking, plasticizing, and antibacterial capability of the polymer network. The organic acid-based bio-composite polymeric films were assessed in terms of swelling index (SI), in vitro degradation, tensile strength (TS), percentage elongation (%E), antibacterial activity, and cytotoxicity attributes. Among these, the MA-based PVA composite films outperformed the CA-based PVA composite film in terms of absorbency (SI 739.29%), mechanical strength (TS 4.88 MPa), and elasticity (%E 103.68%). Furthermore, following a 24-h incubation period, the MA-based films exhibited the highest proliferative effect of 215.59% for the HEK cells. In conclusion, the MA has been inferred to be the most relevant organic acid for the desired optimality of film composition, physical and biological properties, and cost.

On account of their unique shape memory effect (SME), pseudoelasticity, and biomedical applications, shape memory alloys (SMAs) have gained significant acceptance in the industrial trade and biomedical applications over the past few decades. Due to their affordable constituent parts and the availability of large-scale methods that are commonly employed for the manufacturing of stainless steels, Fe-based shape memory alloys offer benefits in commercial production, owing to their low cost compared to NiTi. The increasing insistence on stronger, lighter, and more functional materials paved the way for active materials. SMAs are a distinct grade of active materials. They exhibit attractive attributes like the potential to provide considerable recoverable strain while mechanical loading (superelasticity), shape recovery during heating (shape memory effect), and biocompatibility, which ultimately prove them to be one of the appropriate actuators for applications in the biomedical industry. This paper gives a review of the Martensitic transformation of some of the compositions of Fe-based SMAs, their potential to be used in civil structures as strengthening materials, their applications, and future research needs. This paper also focuses on the application of iron-based SMAs in different fields and the necessity to work on this SMA in the future since results show that Fe-based SMAs have shown good potential and can serve as an apt alternative to Ni-based shape memory alloys, which on the other hand has quite a lot of disadvantages, the key one being costly. Fe-based SMAs are comparatively lower in cost and have a greater scope to work with in the near future.

CuMn₂O₄ (CMO) thin films are produced using a simple hydrothermal method. The influence of reaction duration on the electrodes’ electrochemical performance is investigated. XRD data shows improved crystal structure after 24-h reaction time, with a crystallite size of 12.17 nm. Distinct vibrational peaks associated with Cu–O and Mn–O are observed in the ATR-FTIR spectra, corroborating the spinel formation after 24 h. XPS analysis shows a compositional shift over time, starting with copper hydroxide at 12 h, evolving into a mix of copper and manganese oxides, hydroxides, and oxyhydroxides by 18 h, and achieving the desired spinel composition by 24 h. Microscopic analysis reveals CMO is arranged as small sheet structures, with 4.95 ± 2.92 µm in length after 24-h reaction. The CMO_24h electrode displays a maximum specific capacitance of 1187.50 Fg⁻¹ at a scan rate of 1 mVs⁻¹ in 1 M Na₂SO₄ electrolyte. The electrochemical performance of the synthesized CMO electrodes reveals a high potential for energy storage applications.

Thin films reinforced with chitosan and cellulose nanocrystals (CNC) were produced using the casting process. In this study, the impact of plasticisers and sizing agents such as glycerol and polyvinyl alcohol (PVA) respectively on morphological, structural, thermal, and mechanical properties was investigated. The results showed the blends of CNC/PVA/glycerol gave better results when compared to films produced by blends of chitosan/PVA/glycerol films and chitosan/CNC/PVA/glycerol films. The UV spectroscopy showed 65% transmittance for chitosan/PVA/glycerol films, while the film of CNC/PVA/glycerol showed transmittance of 40%. The transmittance of chitosan/CNC/PVA/glycerol showed 75%. The films formed by the combination of CNC/PVA/glycerol showed better stress/strain properties than other films. The films of all combinations showed good thermal stability between the range of 350 and 450 °C. The morphological study using SEM revealed smooth texture for all the films. The study suggests that the films produced may be used for the food packaging applications due to its thermal stability and stress/strain properties.

The insulating oil serves the dual purpose of providing insulation and cooling within transformers. This investigation aims to explore the impact of various nanoparticles on the dielectric breakdown voltage (BDV) of dielectric oils. The study examines the effect of the concentration of magnetic nanoparticles on the dielectric breakdown voltage of insulating oils. Nanoparticles such as iron (II, III) oxide (Fe₃O₄), cobalt (II, III) oxide (CO₃O₄), and ferrous phosphide (Fe₃P) were utilized to create nanofluids with carrier mediums consisting of mineral oil and synthetic ester oil. BDV determination was conducted using a VDE and S–S electrode system according to IEC 60156 standards. Nanofluid were prepared using a two-step method, and their concentrations ranged from 0.01 g/L, 0.02 g/L, and 0.04 g/L in base oils. Twelve iterations were conducted for each prepared nanofluid, and breakdown voltage measurements were recorded. The results indicate a noteworthy enhancement in the breakdown voltage of nanofluids. The statistical analysis was performed on the dielectric property of nanofluid samples for better breakdown accuracy. The maximum enhancement at specific nanoparticle concentrations was shown by each nanofluid. The results show that under the S–S electrode configuration, the greatest overall enhancement was observed for Fe₃P in mineral oil, with an enhancement of 70.05%, and Fe₃O₄ in synthetic ester oil, with an enhancement of 46.29%.