This paper investigates the spray combustion characteristics of a methanol–DME blended fuel with a DME mole fraction of 0.57 in a constant volume vessel. The rate of heat release (ROHR) was evaluated using pressure-based heat release analysis. The results show that the methanol–DME blended fuel requires a longer injection duration due to the lower LHV (lower heating value), but it exhibits a shorter combustion duration than conventional diesel fuel, together with a higher ROHR normalized by the injection LHV rate and a shorter afterburning duration. To elucidate the relationship between the spray combustion processes and the ROHR characteristics, the spray flame was visualized using schlieren and OH chemiluminescence imaging techniques. In addition, a one-dimensional simulation based on a diesel jet model was conducted to evaluate the distributions of the equivalence ratio. These analyses reveal that the lower theoretical air–fuel ratio, attributed to the oxygenated nature of the methanol–DME blended fuel, reduces the equivalence ratio within the spray, promoting earlier formation of near-stoichiometric mixtures. As a result, the ROHR reaches and sustains its maximum earlier during mixing-controlled combustion, and fuel consumption is enhanced during afterburning.
In this study, we conducted elemental analysis of the mechanical pencil lead and surface layer, wettability evaluation, static tensile testing, and fracture surface observation to clarify the effects of different surface treatment conditions using mechanical pencil lead on the adhesive strength and fracture behavior of steel materials and urethane adhesives. As the results, under 600°C heating conditions, a heat holding time of 30 min resulted in insufficient melting of the mechanical pencil lead, and limited adhesion of carbon and inorganic components, resulting in wettability and adhesive strength comparable to that of untreated materials. On the other hand, under 600°C heating conditions, a holding time of 45 min resulted in the initiation of pencil lead melting, resulting in the adhesion and dispersion of potassium chloride-derived from resin layer of pencil lead, and the formation of moderate carbon and oxide film. As a result, the surface polarity and wettability improved, and the interfacial adhesion strengthened, resulting in high adhesive strength and a higher cohesive failure rate.
X-ray imaging using photon-counting detectors (PCDs) allows for the calculation of quantitative images such as the effective atomic number (Zeff). However, physical phenomena such as characteristic X-ray emission and charge sharing can cause incomplete total absorption events during signal generation, which reduces the accuracy of X-ray penetration analysis. To solve the problem, an anti-coincidence mode (ACM) has been developed, but complete correction has not been established. We aimed to investigate the accuracy of Zeff image when the proposed software-based corrections, namely beam hardening and response function corrections, are added to the hardware-based correction of the ACM. The response function was calculated using the Monte-Carlo simulation code. In a simulation study, we analyzed a phantom composed of virtual materials with Zeff values of 4–16. While sufficient accuracy cannot be achieved by applying only the ACM, it was demonstrated that low-noise Zeff images can be obtained by applying our correction. Furthermore, it was demonstrated that Zeff images of food samples can be generated by using actual non-destructive testing equipment with a 10 m/min transportation speed. In conclusion, our correction procedure can maximize the performance of PCDs, and our findings are essential for promoting imaging techniques concerning quantitative images.
Magnesium (Mg)- based alloys and their composites have recently gained significant interest in the biomedical field as potential biodegradable materials due to their unique mechanical properties, bioresorbability, biocompatibility, and biological activity. Nevertheless, the widespread biomedical applications of Mg-based alloys and composites are still limited mostly by their superior corrosion rates and subsequent loss in mechanical integrity. In recent years, numerous research studies have been conducted to develop biodegradable Mg-based alloys and magnesium-based metal matrix composites (Mg/MMCs) with enhanced corrosion resistance and mechanical properties. In this paper, an effort has been made to discuss the various methodologies for processing biodegradable Mg/MMCs for important clinical applications. The major processing technologies for biodegradable Mg/MMCs, including liquid-state processing (e.g., stir casting), solid-state processing (e.g., powder metallurgy (PM)), in-situ processing, and modern additive manufacturing (e.g., powder bed fusion (PBF), selective laser melting (SLM), and wire arc additive manufacturing (WAAM)), are first briefly introduced. Subsequently, biodegradable Mg-based alloying designs and the current trend in biodegradable Mg-based alloys, including Mg/Ca, Mg/Zn, Mg/Cu, Mg/Sr, and Mg/RE, essential for biomedical applications, are reviewed in detail. This review article also comprehensively discusses the design of reinforcement materials for producing biodegradable Mg/MMCs for clinical applications. The current trends on biodegradable Mg/MMCs, including calcium phosphate (CaP)-based bioceramics, Si-containing bioceramics, biodegradable magnesium oxide (MgO), and carbon materials reinforced Mg/MMCs, are discussed. Special emphasis has been placed on the production techniques and various behaviors (e.g., mechanical properties, microstructure, biocompatibility, and corrosion behaviors) displayed by micro/nano-sized particles reinforced Mg/MMCs. The potential engineering applications of Mg/MMCs are also introduced. Ultimately, this review highlights the prospects of biodegradable Mg-based alloys and Mg/MMCs biomaterials in various biomedical applications. This review will serve as a valuable reference for young researchers and industry personnel with a comprehensive understanding of biodegradable Mg/MMCs utilized in biomedical applications.
We study the scattering and conductometric properties of a semiflexible polyelectrolyte, carboxymethyl cellulose (CMC), with monovalent and divalent counterions in aqueous media without added salts. The scattering patterns for the magnesium salts of CMC display a broad shoulder instead of the scattering peak observed for the monovalent salts. This suggests weaker electrostatic repulsion between chains and a consequent loss of local order. The result is consistent with conductivity measurements, which reveal that the effective charge of the backbone for MgCMC is approximately half that of NaCMC. The decrease in charge density agrees with Oosawa–Manning condensation, which expects the charge density to be inversely proportional to the counterion valence. Alkali metal counterions show large differences in ion-pair formation but only a weak effect in counterion condensation. We suggest that paired ions are a subset of condensed ions. A review of different methods to evaluate counterion condensation, including potentiometry, osmometry and viscosity-based methods is presented. Qualitative agreement between these methods is found and possible reasons for the discrepancies are discussed.
