Embrittlement Fracture Behavior and Mechanical Properties in Heat-Affected Zone of Welded Maraging Steel.

In welded maraging steels, mechanical properties, particularly ductility and toughness, are often compromised in the heat-affected zone (HAZ). This study focuses on 300-grade maraging steel bars, solution annealed at 1123 K for 1.5 h (5.4 ks) and welded using gas tungsten arc welding, followed by a post-weld heat treatment at 753 K for 13.33 h (48 ks). In situ observations during three-point bending tests on HAZ samples featuring coarsened prior austenite grain sizes were conducted to examine damage behavior and the crack path near the crack tip. The main crack initiated at the peak applied load during the bending test and, upon further loading, exhibited significant deflection and extension accompanied by numerous microcracks and localized crack branching. Distinctive damage features, such as transgranular cracking across block regions, intense intergranular cracking along packet boundaries with a pronounced shear component, and crowding of microcracks ahead of the crack tip, were observed in the HAZ sample during the in situ test. The interaction between the main crack tip and microcracks and its influence on the local crack propagation driving force was discussed using fracture mechanics. Experimental results, including tensile fracture surface observations and in situ images, along with analysis of the stress anti-shielding effect by microcracks, suggest that the HAZ sample exhibits embrittlement fracture behavior with lower ductility and toughness compared to the base metal sample.

Publisher Correction: Clinical evaluation of fully automated molecular diagnostic system "Simprova" for influenza virus, respiratory syncytial virus, and human metapneumovirus.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Clinical evaluation of fully automated molecular diagnostic system "Simprova" for influenza virus, respiratory syncytial virus, and human metapneumovirus.

Influenza virus, respiratory syncytial virus, and human metapneumovirus commonly cause acute upper and lower respiratory tract infections, especially in children and the elderly. Although rapid antigen detection tests for detecting these infections have been introduced recently, these are less sensitive than nucleic acid amplification tests. More recently, highly sensitive point-of-care testings (POCTs) have been developed based on nucleic acid amplification tests, which are easy to use in clinical settings. In this study, loop-mediated isothermal amplification (LAMP)-based POCT "Simprova" to detect influenza A and B viruses, respiratory syncytial virus, and human metapneumovirus was developed. Simprova system is fully automated and does not require skilled personnel. In addition, positive results can be achieved faster than with PCR. In this study, the accuracy of the POCT was retrospectively analyzed using 241 frozen stocked specimens. Additionally, the usability of the Simprova at clinical sites was assessed in a prospective clinical study using 380 clinical specimens and compared to those of real-time PCR and rapid antigen detection test. The novel LAMP-based POCT demonstrated high sensitivity and specificity in characterizing clinical specimens from patients with influenza-like illnesses. The Simprova is a powerful tool for early diagnosis of respiratory viral infections in point-of-care settings.

Fully Automated Molecular Diagnostic System "Simprova" for Simultaneous Testing of Multiple Items.

Nucleic acid amplification-based diagnostics is known as one of the molecular diagnostic systems that allows higher sensitive detection of pathogens than test methods such as immunoassay. However, it has not been widely used because it is complicated to use and takes a long time to generate results. On the other hand, development of fully automated molecular diagnostic systems has been growing around the world as demand for such systems from physicians and laboratory technicians has increased. To meet this demand, we have developed the "Simprova" fully automated molecular diagnostic system, which takes advantage of LAMP (Loop-mediated Isothermal Amplification), a method Eiken Chemical Co., Ltd. invented. Simprova comprises a master unit that controls the entire system and a test unit that extracts and purifies nucleic acid from samples (pretreatment), and uses the LAMP method to detect and amplify nucleic acid. Users can obtain test results automatically by simply installing a pretreatment cartridge, a multi-well testing chip and the sample in the test unit. The multi-well testing chip has 25 reaction wells connected by channels and enables simultaneous testing of multiple targets with one sample. Turnaround time for one test is approximately 30 minutes. Since a conventional extraction and purification method using magnetic-bead separation is used for the pretreatment, nucleic acid can be extracted from serum, plasma, whole blood, urine, and sputum, for example. In addition, the system can perform random-access testing by connecting four test units to the master unit to realize near-the-patient testing. Simprova is therefore a robust and useful system for a wide variety of applications.

Point-of-care testing system enabling 30 min detection of influenza genes.

We developed a portable and easy-to-use nucleic acid amplification test (NAT) system for use in point-of-care testing (POCT). The system shows sensitivity that is sufficiently higher than that of the currently available rapid diagnostic kit and is comparable to that of real-time reverse transcription polymerase chain reaction (RT-PCR) for influenza testing.