The Degradation of Intramuscular Connective Tissue In Vitro with Purified Cathepsin L from Bovine Pancreas.

To investigate the possible degradation of the intramuscular connective tissue (IMCT) with cathepsin L, isolated IMCTs were incubated with purified cathepsin L in vitro. Here, we prepared purified cathepsin L from bovine pancreas by using DEAE Sephacel, Sephacryl S-100 HR, SP Sepharose FF, and con A-Sepharose affinity chromatography in sequence. An SDS-PAGE analysis of CNBr-digested peptides showed that the degradation of collagen in IMCT could take place on terminal non-helical peptides rather than the triple helix region. Decorin (DCN) was clearly degraded at a pH of 5.0. The TP and TO of intramuscular connective tissue decreased to 41.41 °C and 43.79 °C, respectively. In the cathepsin L treatment of pH 5.0, the decreases in the TP and TO of IMCT were more sensitive than they were at pH 5.5~6.5.

Effect of Chromium Carbide Addition on the Microstructures and Properties in Dual Carbide Phases Reinforced Ni-Based Composite Coatings by Plasma Cladding.

Cr3C2-modified NiCr-TiC composite coatings were prepared using the plasma spraying technique for different Cr3C2 contents on the microstructure and the properties of the Ni-based TiC cladding layer were investigated. The microstructures of the coatings were characterized using scanning electron microscopy, and the friction and wear performance of the coating was evaluated by the wear tests. The results revealed that the surfaces of the Cr3C2-modified NiCr-TiC composite coatings with varying Cr3C2 contents were dense and smooth. TiC was uniformly distributed throughout the entire coating, forming a gradient interface between the binder phase of the Ni-based alloy and the hard phase of TiC. At high temperatures, Cr3C2 decomposes, with some chromium diffusing and forming complex carbides around TiC, some chromium solubilizes with Fe, Ni, and other elements. An increase in chromium carbide content leads to an upward trend in hardness. The measured hardness of the coatings ranged from 600 to 850 HV3 and tended to increase with increasing Cr3C2 content. When the mass fraction of Cr3C2 reached 30%, the hardness increased to 850 HV3, and the cracks and defects were observed in the coating, resulting in a wear resistance decline.

Investigation on Microstructures and High-Temperature Oxidation Resistance of Cr Coatings on Zircaloy-4 by Multi-Arc Ion Plating Technology.

Introducing the oxidation-resistant coating on Zr alloy is considered to be one of the potential solutions for accident-tolerant fuel (ATF) materials. In this study, pure Cr coatings were prepared on a Zircaloy-4 (Zry-4) alloy surface by multi-arc ion plating under different process parameters. The ability of Cr coating on Zry-4 alloy cladding to improve the oxidation resistance to prevent a loss-of-coolant accident (LOCA) was studied. The microstructure of Cr coating was analyzed using the EBSD technique, and the high-temperature steam oxidation was tested at 800, 1000 and 1200 °C. Compared with the original Zry-4 alloy, the samples with Cr coatings exhibited much better oxidation resistance under different high-temperature steam oxidation conditions. However, the Cr coating exhibited columnar grain, strong preferred orientation and (001) fiber texture. The columnar grain boundaries provided paths for the diffusion of oxygen atoms to the Zry-4 alloy matrix at high temperatures. The results showed that the oxidation film of Cr coating with relatively random grain orientation was compact and uniform and exhibited the best oxidation resistance at high temperatures.

Resonance vibration ameliorating tenderness of yak longissimus thoracis et lumborum: A novel physical tenderization technology.

Physical tenderization technologies for beef have been of particular interest to the meat industry. Here a novel tenderization technology by mechanical resonance vibration was proposed. The fundamental natural frequency (NFf) of the yak longissimus thoracis et lumborum (LTL) was obtained through a hammer impacting on the muscle, and was reported to be 24.89 Hz. The tensile stress and Warner-Bratzler shear force of the yak meat were decreased by using the obtained NFf as the frequency of resonance vibration (RV), and only linear elastic deformation was found in stress-strain behavior of the vibrated meat. The variation of mechanical properties in post-rigor meat is responsible for the disappearance of the M-bands, shortening of the A-bands, and lengthening change in I-bands, rather than of the sarcomere length. The research demonstrated that RV treatment resulted in the M-band disappearance, the extensively detachment of endomysium from the myofibers, and the destruction of the linkages between α-actinin and thin filaments as well as other linkages.

Effects of TiAl Alloy as a Binder on Cubic Boron Nitride Composites.

Owing to their extreme hardness, cubic boron nitride (cBN) composites are widely used in cutting applications. The performance of cBN composites is closely related to the characteristics of the binder. Therefore, novel binders must be developed to improve the performance of cBN composites. In the present work, TiAl intermetallics were used as binders to fabricate cBN composites by employing a high-temperature and high-pressure sintering method. The phase transformation, sintering reaction mechanism, thermal stability, and mechanical properties of the resultant cBN composites were investigated. It was found that during the sintering process, Ti atoms preferentially reacted with boron nitride particles, whereas Al atoms enriched and transformed into TiAl3 phases and formed cBN/AlN, AlB2/TiN, and TiB2/TiAl3-layered structures eventually. The composites maintained good oxidation resistance at 1200 °C. A decrease in the particle size of the TiAl binder improved the uniformity of particle size distribution and increased the flexural strength of the composites.

Effect of Ti/Ni Coating of Diamond Particles on Microstructure and Properties of High-Entropy Alloy/Diamond Composites.

In this study, an effective way of applying Ti/Ni deposited coating to the surface of diamond single crystal particles by magnetron sputtering was proposed and novel high-entropy alloy (HEA)/diamond composites were prepared by spark plasma sintering (SPS). The results show that the interfacial bonding state of the coated diamond composite is obviously better than that of the uncoated diamond composite. Corresponding mechanical properties such as hardness, density, transverse fracture strength and friction properties of the coated diamond composite were also found to be better than those of the uncoated diamond composite. The effects of interface structure and defects on the mechanical properties of HEA/diamond composites were investigated. The research directions for further improving the structure and properties of high-entropy alloy/diamond composites were proposed.

Effect of Binding and Dispersion Behavior of High-Entropy Alloy (HEA) Powders on the Microstructure and Mechanical Properties in a Novel HEA/Diamond Composite.

This study reports the results of the addition of diamonds in the sintering process of a FCC-structured CoCrFeNiMo high-entropy alloy. The effect of raw powder states such as elemental mixed (EM) powder, gas atomization (GA) powder and mechanical alloying (MA) powder on the uniformity of constituent phase was also investigated. Examination of microstructure and evaluation of mechanical properties of the composites depending on the mixing processes were performed. As a result, GA+MA powder composite showed the highest mechanical properties. The experimental results indicated that the powder manufacturing method was an essential parameter to determine the quality of HEA/diamond composites such as the uniformity of phase and binding behavior.

Polysynthetic twinned TiAl single crystals for high-temperature applications.

TiAl alloys are lightweight, show decent corrosion resistance and have good mechanical properties at elevated temperatures, making them appealing for high-temperature applications. However, polysynthetic twinned TiAl single crystals fabricated by crystal-seeding methods face substantial challenges, and their service temperatures cannot be raised further. Here we report that Ti-45Al-8Nb single crystals with controlled lamellar orientations can be fabricated by directional solidification without the use of complex seeding methods. Samples with 0° lamellar orientation exhibit an average room temperature tensile ductility of 6.9% and a yield strength of 708 MPa, with a failure strength of 978 MPa due to the formation of extensive nanotwins during plastic deformation. At 900 °C yield strength remains high at 637 MPa, with 8.1% ductility and superior creep resistance. Thus, this TiAl single-crystal alloy could provide expanded opportunities for higher-temperature applications, such as in aeronautics and aerospace.

NADPH oxidase 1 and its derived reactive oxygen species mediated tissue injury and repair.

Reactive oxygen species are mostly viewed to cause oxidative damage to various cells and induce organ dysfunction after ischemia-reperfusion injury. However, they are also considered as crucial molecules for cellular signal transduction in biology. NADPH oxidase, whose only function is reactive oxygen species production, has been extensively investigated in many cell types especially phagocytes. The deficiency of NADPH oxidase extends the process of inflammation and delays tissue repair, which causes chronic granulomatous disease in patients. NADPH oxidase 1, one member of the NADPH oxidase family, is not only constitutively expressed in a variety of tissues, but also induced to increase expression in both mRNA and protein levels under many circumstances. NADPH oxidase 1 and its derived reactive oxygen species are suggested to be able to regulate inflammation reaction, cell proliferation and migration, and extracellular matrix synthesis, which contribute to the processes of tissue injury and repair.