Tensile properties of an as-cast CoCrFeMnNi high-entropy alloy were investigated at various temperatures ranging from −160 to 1000°C. The tensile strength and ductility did not vary significantly ...with loading direction, despite the alloy’s strongly preferred crystallographic orientation. The impact toughness values of the as-cast high-entropy alloy were much higher than those of many traditional alloys, particularly at low temperatures. The mechanical properties of the as-cast high-entropy alloy were compared with those of wrought high-entropy alloy and noticeable differences between the two alloys were found. The maximum tensile ductility and three different strain hardening stages were observed at 500°C in the as-cast structure. Transmission electron microscopy observations demonstrated that the initiation of deformation twinning was very active even at 500°C. A simple calculation suggests that very large grains of the as-cast structure induced a reduction in twinning stress, retarding the onset of strain localization.
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•The high temperature step–wise creep behavior of the additively manufactured carbon–containing high–entropy alloy has been firstly studied.•The effect of the supersaturated ...carbon–mediated nano–carbide precipitation by post heat–treatment on the creep resistance has been elucidated.•The underlying mechanism that responsible for the superior creep resistance has been profoundly revealed in multiple scales.
A carbon–containing CrMnFeCoNi high–entropy alloy (C–HEA) nanocomposite was additively manufactured via a laser powder bed fusion (LPBF) process combined with subsequent heat treatment. Exposure of the LPBF C–HEA to this additional heat–treatment step not only resulted in heterogeneous–structured grains of which the substructure is decorated with a dislocation network, but also uniformly distributed nanosized carbide precipitates at the grain and substructure boundaries. A multistep creep test conducted on the LPBF C–HEA at 873 K enabled the stress exponent, n, to be obtained with values of 3.03 in the low stress region (175–250 MPa) and 6.99 in the high stress region (250–325 MPa). The LPBF C–HEA alloy exhibited superior high–temperature creep resistance (i.e., the creep rate and threshold stress were minimized) compared to other CrMnFeCoNi HEAs. The mechanism underlying the creep resistance and unique creep deformation behavior of the LPBF C–HEA alloy is discussed on the basis of electron channeling contrast imaging and electron backscatter diffraction analyses.
The dual-phase AlCoCrFeNi alloy exhibits excellent specific strength in the 773–873 K temperature range. However, the phase transformation taking place above 773 K hinders its structural use at ...higher temperatures. In the present study, the temperature dependence of the specific strength of the AlCoCrFeNi alloy has been examined from a microstructural point of view. One of the key findings of this work is that the high-temperature phase stability of the dual-phase alloy is strongly affected by its microstructural morphology; this finding provides new insights into the application of high-entropy alloys as high-temperature structural materials, for instance in aerospace engine components.
•AlCoCrFeNi alloy exhibits excellent specific strength in 773–873 K temperature range.•The yield strength of the AlCoCrFeNi alloy exhibits a sharp drop above 773 K.•The maximum-use temperature can be increased by suppressing the phase transformation.
This research proposes an ontological inference process to automate the process of searching for the most appropriate work items, which is limited to tiling in this case study. The proposed ...ontological approach can help engineers to find work items with greater ease and consistency. Suggestions are also made for further research on ways of improving the accuracy of BIM-based quantity take-off, and developing a methodology to match between work items which are expressed as different terms; however, the proposed approach emphasizes the automation of searches using BIM data to find items suitable for building elements and materials. To enable automated inference, this study establishes (1) a work condition ontology that consists of the determinants required to select work items, (2) a work item ontology, which consists of the factors defining the tiling method, and (3) semantic reasoning rules. By conducting a case study to demonstrate the proposed ontological inference process in a real-world situation, we confirm that the proposed process can provide consistent results; however, since work items differ depending on construction type and technological advancement, the work item ontology should be continually revised and updated.
The ontological inference process removes the need for the intervention of a cost estimator's subjectivity in searching for an appropriate work item. Also, if ontology is elaborately defined by the knowledge of experienced engineers, then accurate and consistent results can be obtained. In addition, the proposed process will assist cost estimators to use BIM data more easily, and it will help the expansion of BIM-based construction management.
•We develop the ontology that enables automated search of most appropriate work items•The scope of ontology is limited to tile work.•We propose ontological approach to building cost estimation.
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•Influence of heterogeneous structure and nano-sized σ phase on mechanical property and deformation mechanism was examined.•The heterogeneous structured 316L stainless steel showed ...enhanced tensile strength and ductility.•Martensitic transformation surrounding the sigma phase prevented microcrack propagation into the matrix.•Heterostructures accelerated deformation-induced martensitic transformation, leading to superior mechanical properties.
In this study, we produced both homogeneous and heterogeneous-structured 316L austenitic stainless steels (SSs), each exhibiting comparable levels of yield strength (YS). Despite their similar YS, the heterogeneous-structured 316L SS exhibits a significantly higher tensile strength of ∼1 GPa compared to the homogeneous-structured 316L SS (∼832 MPa), and slightly higher fracture strain. The enhanced tensile strength and work hardening behavior in the heterogeneous-structured 316L SS were mainly attributed to the hetero-deformation induced (HDI) hardening, accelerated deformation-induced martensitic transformation (DIMT), and the presence of the nano-sized σ-phase particles. Our findings provide insights into the development of metastable heterogeneous-structured face-centered cubic (FCC) metallic materials with outstanding mechanical properties.
Optical biochemical assays that utilize traditional optical signaling labels, such as fluorophores and fluorescent nanoparticles, have been extensively applied in the development of optical ...biosensors. However, traditional optical-label-based analytical approaches require expensive and sophisticated optical instruments; thus, the application of traditional optical-label-based biochemical assays to optical biosensors in point-of-care testing (POCT) concepts that require cost-effectiveness and user-friendliness remains challenging. Retroreflection-based optical biosensing technology that utilizes micro-sized retroreflectors as an optical signaling label is being studied as a promising technological alternative to overcome the drawbacks of conventional optical-label-based biosensors. Retroreflection is an optical phenomenon whereby light rays strike a specific surface, a retroreflector, and are redirected to the light source along the inverse direction of the incident light. Biosensors that involve the retroreflection principle and retroreflector-type optical label offer distinctive advantages, such as the cost-effective simplification of optical instrument configuration, highly flexible applicability to various biochemical assays, and high analytical capability; therefore, their further applications toward the biosensing platform for POCT is highly promising. This review introduces the fundamentals of retroreflection and summarizes recent research achievements of retroreflection-based optical biosensor development from the perspective of how retroreflectors can be coupled and utilized with the optical biosensing principle as optical signal labels. The expected future applications of retroreflection-based optical biosensor technology is also discussed.
•Retroreflection-based optical sensing that utilizes retroreflectors as new optical signaling probe is discussed.•Principle of retroreflection phenomena and preparation of retroreflection-based biosensor were presented.•Benefits expected and achieved by retroreflection comparing to conventional optical probes are discussed.•Application fields of retroreflection-based biosensing and bioimaging technology are highlighted.
Inconel 625 alloy was fabricated using fused deposition modeling (FDM), an emerging advanced additive manufacturing (AM) technique. Subsequently, the effects of hot isostatic pressing (HIP) on its ...microstructure and mechanical properties were investigated. Notably, HIP treatment significantly reduced the defect density, resulting in enhanced tensile ductility.
Here, we proposed a retroreflective optical immunoassay platform by introducing the intrinsic sedimentation characteristics of a micro-retroreflector, namely retroreflective Janus particles (RJPs), ...wherein the sediment-based passive movement of RJPs minimised the random errors due to human involvement and resulted in a simple procedure that does not require the washing step, to follow the concept of point-of-care testing. The transparent sensing interface and the sedimentation property of RJPs were combined to develop a practical retroreflective immunoassay platform. For the sensing surface, transparent silanized poly(methyl methacrylate) was applied to the inverted focusing method. In the retroreflection phenomenon, as the incident light returns to its source by the retroreflector, efficient design of the retroreflective optical path between the light source and retroreflector can be crucial in signal registration. While preparing the RJP-bound transparent substrate on the microfluidic channel, the signal could be achieved more efficiently by directly focusing on the sensing interface, and not
via
the fluidic channels. To integrate this to build an immunoassay protocol, the sedimentation property of RJPs was employed for microfluidic chip inversion-based particle movement control, which was utilised for both luring and separating RJPs on the sensing surface, resulting in a wash-free immunoassay without any human involvement. To ensure accurate analysis, a time-lapse imaging-based image processing was conducted to eliminate the non-specific signals. To validate the applicability of the proposed immunoassay platform, quantification of acute cardiac infarction marker creatine kinase-MB was performed.
A wash-free nonspectroscopic optical immunoassay system by controlling retroreflective Janus microparticles movement in a microfluidic chip was developed to minimize random errors under the point-of-care testing environment.
Herein, we introduce a smartphone-integrated immunosensor based on non-spectroscopic optical detection. Sedimentation of the retroreflector and gentle inversion of the microfluidic chip was chosen as ...biosensing principles to ensure minimal human involvement. To realize this, wash-free immunosensing was implemented on a polymeric microfluidic chip device fabricated for light signal penetration in retroreflection signal acquisition. Applying a transparent chip and passive modulation of retroreflectors enabled the minimization of human error during sensing. In addition, a retroreflection-detectable optical gadget was constructed for integration with the commercial smartphone. The gadget had an optical chamber that induced retroreflection by integration with a smartphone. When the micro-sized reflector, named the retroreflective Janus microparticle, reacted on the sensing surface, the incident light was retroreflected towards the image sensor and quantified by a smartphone-installed Android application package. The developed application package features include time-lapse image capture performed by manipulating LED flash and camera modules, and quantification of retroreflected signal counts by image processing of time-lapse images. With this platform, the user could independently commence optical signal processing without a complicated optical setup and running software on a PC, and sensitive and reproducible immunosensing results could be obtained. The applicability test for creatine kinase-myocardial band detection from the buffer to serum was conducted and presented a calibration curve of 0–1000 ng/mL within 1 h. With the developed system, we believe that the applicability of the platform in bioanalytical detection can be expanded.
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•The retroreflection-based optical immunosensor has been developed to operate on smartphone.•A non-spectroscopic optical setup was constructed on a smartphone without additional optical components.•A wash-free immunosensing was demonstrated using the sedimentation of optical probe to minimize human involvement.•Time-lapse image acquisition and image processing algorithms were developed and installed on the Android APP.•CK-MB spiked serum sample was analyzed on a smartphone APP for quantitative POCT.
Loop-mediated isothermal amplification (LAMP) is an outstanding method for molecular diagnostics, as the rapid, specific, and sensitive amplification of target genes is possible. However, it is ...necessary to measure fluorescence in the quantitative analysis of LAMP products, so a sophisticated optical setup is required. This study tried to develop a novel sensing method that can quantify target analytes with simple equipment, such as nonspectroscopic white light and a CMOS camera. To achieve this, a retroreflective Janus particle (RJP) as a probe and specially designed loop primers, fluorescein isothiocyanate (FITC)- and biotin-modified loop primers, were introduced into the LAMP system. By performing LAMP in the presence of designed primers, double-stranded amplicons possessing FITC and biotin labels at each end are generated in proportion to the quantity of the target pathogen. Using the anti-FITC antibody-modified sensing surface and streptavidin-conjugated RJP probes, the amplicons can be captured in sandwich-configuration and detected under nonspectroscopic conditions composed of white light and a camera. To confirm the feasibility of the sensing system, the
invA
gene of
Salmonella
was selected as the target. It was possible to quantitatively analyze the
Salmonella
concentration from 0 to 10
6
colony-forming units, sufficiently covering the required detection range. In addition, quantitative analyses of pathogens in contaminated food sources, including milk and chicken meat, were successfully conducted with a limit of detection of 10 CFU.
Loop-mediated isothermal amplification (LAMP), associated with nonspectroscopic retroreflection-based affinity sensing, is an outstanding method for quantitative analysis of pathogen.
