One-Step Hybrid Bending/Diffusion Bonding Process and Analysis of the Bonding Characteristics of Titanium Alloy Sheets.

A one-step hybrid bending/diffusion bonding process (HB/DBP) was developed for application to Ti-6Al-4V sheets to effectively improve buy-to-fly (BTF) ratio of aircraft parts, integrating sequential diffusion bonding followed by a bending process. The resulting bonding characteristics of these titanium alloy sheets were analyzed. Microstructural analysis and mechanical lap shear tests were performed to estimate the bonding quality. Additionally, bonding ratio, thickness strain, and shear strength were evaluated in relation to pressure under increasing temperature. When the applied pressure was lower than 0.5 MPa, early failure occurred at the joint of the specimens. However, when high pressure was applied, early failure occurred near the joint. To discuss the phenomenon, time-dependent viscoplastic material properties were characterized, and a numerical simulation analysis was performed. Viscoplastic deformation was observed around the bending area, which caused weakness around the bond under high-pressure conditions. A prototype of a Y-shaped heat shield was manufactured and the buy-to-fly ratio was effectively improved using the newly developed process. This study demonstrates the potential of applying the developed process for producing aircraft parts and the importance of viscoplastic behavior for the analysis of final product reliability.

In situ health monitoring of multiscale structures and its instantaneous verification using mechanoluminescence and dual machine learning.

Extensive changes in the legal, commercial and technical requirements in engineering fields have necessitated automated real-time structural health monitoring (SHM) and instantaneous verification. An integrated system with mechanoluminescence (ML) and dual artificial intelligence (AI) modules with subsidiary finite element method (FEM) simulation is designed for in situ SHM and instantaneous verification. The ML module detects the exact position of a crack tip and evaluates the significance of existing cracks with a plastic stress-intensity factor (PSIF; K P ). ML fields and their corresponding K p M L values are referenced and verified using the FEM simulation and bidirectional generative adversarial network (GAN). Well-trained forward and backward GANs create fake FEM and ML images that appear authentic to observers; a convolutional neural network is used to postulate precise PSIFs from fake images. Finally, the reliability of the proposed system to satisfy existing commercial requirements is validated in terms of tension, compact tension, AI, and instrumentation.

Effects of the synthetic coprisin analog peptide, CopA3 in pathogenic microorganisms and mammalian cancer cells.

A synthetic coprisin analog peptide, 9-mer dimer CopA3 (CopA3) was designed based on a defensin-like peptide, Coprisin, isolated from the bacteria-immunized dung beetle Copris tripartitus. Here, CopA3 was investigated for its antimicrobial activity and cancer cell growth inhibition. CopA3 showed antimicrobial activities against various pathogenic bacteria and yeast fungus with MIC values in 2~32 µM ranges, and inhibited the cell viabilities of pancreatic and hepatocellular cancer cells, except MIAPaca2, Hep3B, and HepG2 cells, in a dose-dependent manner. The average IC(50) values of CopA3 against pancreatic and hepatocellular cancer cells were 61.7 µM and 67.8 µM, respectively. The results indicate that CopA3 has potential in the treatments of pancreatic and hepatocellular cancers as well as microorganism infection disease.

Synthetic Coprisin analog peptide, D-CopA3 has antimicrobial activity and pro-apoptotic effects in human leukemia cells.

Recently, we reported that the synthetic Coprisin analog peptide 9-mer dimer CopA3 (consisted of all-L amino acid sequence) was designed based on a defensin-like peptide, Coprisin isolated from Copris tripartitus. The 9-mer dimer CopA3 (L-CopA3) had antibacterial activity and induced apoptosis in human leukemia cells via a caspase-independent pathway. In this study, all of amino acid sequences of L-CopA3 were modified to all D-form amino acids (D-CopA3) to develop a more effective antimicrobial peptide. We investigated whether D-CopA3 had antimicrobial activities against pathogenic microorganisms and proapoptotic effects in human leukemia cells (U937, Jurkat, and AML-2). The synthetic peptide D-CopA3 had antimicrobial activities against various pathogenic bacteria and yeast fungus with MIC values in the 4~64 microM range. Moreover, D-CopA3 caused cell growth inhibition, and increased the chromosomal DNA fragmentation and the expression of inflammatory cytokines, TNF-alpha and IL1-beta, transcripts in human leukemia cells. The all-D amino acid peptide D-CopA3 proved as effective as the L-CopA3 reported previously. These results provide the basis for developing D-CopA3 as a new antibiotic peptide.

Rate-equation model for the loading-rate-dependent mechanoluminescence of SrAl2O4:Eu2+,Dy3+.

The mechanoluminescence (ML) of SrAl2O4:Eu2+,Dy3+ (SAO) phosphors was monitored as a function of its instantaneous loading rate, on which it was found to be strongly dependent. The effect of the loading rate on the ML of SAO was investigated in a systematic manner using rate equations involving the loading rate term. The rate equations and the experimental data matched well. We confirmed that the ML of SAO was created by the change in load rather than by the static load, and that the loading rate determined the shape of the ML versus the time curve in the transient regime.