The purpose of machining operations is to make specific shapes or surface characteristics for a product. Conditions for machining operations were traditionally selected based on geometry and surface finish requirements. However, nowadays, many researchers are optimizing machining parameters since high-quality products can be produced using more expensive and advanced machines and tools. There are a few methods to optimize the machining process, such as minimizing unit production time or cost or maximizing profit. This research focused on maximizing the profit of computer numerical control (CNC) milling operations by optimizing machining parameters. Cutting speeds and feed are considered as the main process variables to maximize the profit of CNC milling operations as they have the greatest effect on machining operation. In this research, the Nelder–Mead simplex method was used to maximize the profit of CNC milling processes by optimizing machining parameters. The Nelder–Mead simplex method was used to calculate best, worst, and second-worst value based on an initial guess. The possible range of machining parameters was limited by several constraints. The Nelder–Mead simplex method yielded a profit of 3.45 ($/min) when applied to a commonly used case study model.

Polycaprolactone (PCL) has been one of the most popular biomaterials in tissue engineering due to its relatively low melting temperature, excellent thermal stability, and cost-effectiveness. However, its low cell attraction, low elastic modulus, and long-term degradation time have limited its application in a wide range of scaffold studies. Dimethyl sulfone (DMSO₂) is a stable and non-hazardous organosulfur compound with low viscosity and high surface tension. PCL and DMSO₂ composites may overcome the limitations of PCL as a biomaterial and tailor the properties of biocomposites. In this study, PCL and DMSO₂ composites were investigated as a new bio-scaffold material to increase hydrophilicity and mechanical properties and tailor degradation properties in vitro. PCL and DMSO₂ were physically mixed with 10, 20, and 30 wt% of DMSO₂ to evaluate thermal, hydrophilicity, mechanical, and degradation properties of the composites. The water contact angle of the composites for hydrophilicity decreased by 15.5% compared to pure PCL. The experimental results showed that the mechanical and degradation properties of PCL and DMSO₂ were better than those of pure PCL, and the properties can be tuned by regulating DMSO2 concentration in the PCL matrix. The elastic modulus of the composite with 30 wt% of DMSO2 showed 532 MPa, and its degradation time was 18 times faster than that of PCL.

Manganese (II) chloride tetrahydrate, classified as an inorganic phase-change material (PCM), can be used as a thermal energy storage material, saving and releasing thermal energy during its phase transitions. In this study, thermophysical properties, such as phase change temperatures, latent heat, and thermal conductivities, of four types of MnCl₂·4H₂O PCMs were investigated under single and dual phases (liquid-, solid-, and dual-phase PCMs) using differential scanning calorimetry (DSC) and a heat flow meter. PCMs with a liquid or dual phases exhibited superheating issues, and their melting temperatures were 7 to 10 °C higher than the reference melting temperatures. The PCMs had latent heats between 146 and 176 J/g in the temperature range of 23 to 45 °C under the endothermic process. Severe supercooling during the exothermic process was observed in all as-received specimens, but was mitigated in the homogenization-treated specimen, which sustained an increase in solidification temperature of about 15 °C compared with the as-received and treated PCMs. The diffusivities of PCMs were between 9.76 × 10⁻⁶ and 2.35 × 10⁻⁵ mm²/s. The diffusivities of the PCMs in the solid phase were higher than those in the liquid phase. During the initial holding time of the endothermic process, the PCM in the liquid phase could not be fully solidified due to an insufficient initial holding time and very low diffusivity, which caused superheating during the DSC measurement. Moreover, in the exothermic process, a fast cooling rate of 5 °C/min and low thermal diffusivity caused supercooling. In particular, the diffusivity of the liquid PCM was lower than those of the solid PCM and other PCMs, which caused extremely high supercooling during the DSC measurement. This paper provides the thermophysical properties of MnCl₂·4H₂O PCMs, which are not available in the literature. The homogeneity of PCMs in their initial states and their heating/cooling rates were identified, and constitute important factors for accurately measuring the thermophysical properties of PCMs.

Copper nanowires and Cu-Ag nanowires have various potential applications, such as transparent conductive film, flexible electronics, and conductive filler. In this study, we developed a new green fabrication method for silver-coated copper nanowires using methylsulfonylmethane (DMSO₂), which is an environmentally friendly chemical at the food-grade level, to replace toxic chemicals, including ammonia, in the silver coating process. Copper nanowires were synthesized under various reaction temperatures and concentrations of hydrazine (N₂H₄), ethylenediamine (EDA), sodium hydroxide (NaOH), and copper precursor. The reaction temperature higher than 70 °C caused the oxidation of copper products and evaporation of the sample solution. The optimal conditions to synthesize copper nanowires more than 18 µm in length and 25–45 nm in diameter were determined: 9 M of NaOH, 50 µL of EDA, 17 mM of CuCl₂, 5.7 mM of N₂H₄, and 70 °C reaction temperature. Cu-Ag nanowires, which have about a 12 nm thick silver shell, were successfully fabricated at room temperature under 1 mM of silver nitrate (AgNO₃) and 1 wt % of DMSO₂. Synthesis conditions for copper and silver-coated copper nanowires have been optimized.

In this study, a new green synthesis method for two-dimensional (2D) copper nanosheets is developed using methylsulfonylmethane (DMSO₂). The chemical composition and light absorption of 2D copper nanosheets are also studied. A new green method is mainly to utilize DMSO₂, which is environmentally friendly enough to be considered a food-grade chemical, unlike the conventional method using toxic chemicals, such as ammonia and hydrazine (N₂H₄). With a reducing agent, the aggregation of uncertain copper products was produced in the absence of DMSO₂, while 2D copper nanosheets were formed in the presence of DMSO₂. The optimum concentration of DMSO₂ as a surfactant was determined to be 2 M, resulting in large surface areas with regular edges. FTIR spectrum confirmed C–H bonding from DMSO₂ used to synthesize 2D copper nanosheets. The light absorption peak was revealed at 800 nm in the UV–vis spectrum. This proposed new green method not only has a simpler process than the conventional methods, such as hydrothermal method and chemical bath deposition, but also substitutes toxic chemicals with DMSO₂. 2D copper nanosheets can be used for various applications, including conductive filler or ink in the flexible electronics and laser photonics fields.

This paper investigates the fatigue characteristics of a new extruded aluminum 7175, with an experimental composition which uses a magnesium-calcium alloy during the alloying process instead of the standard pure magnesium. This new aluminum 7175, dubbed aluminum ECO7175v1, results in a cleaner manufacturing process and improves mechanical properties. The fatigue behavior of the new aluminum ECO7175v1 T74 temper is investigated. Experimental data show that the fatigue life of ECO7175v1-T74 aluminum can exceed ${10}^7$ cycles with a fatigue strength of approximately 207 MPa, about 36% of its tensile strength. Fractography results show that failure modes are predominately ductile near the surface and brittle toward the center. In addition, at higher stresses, crack initiation points are typically at the surface of the specimens, compared with those at lower stresses. Irrespective of the stresses to which the specimens are subjected, all crack initiation points are located at the surface and no inclusions to act as stress concentrators are seen.