Microstructural Characteristics and Properties of Laser-Welded Diamond Saw Blade with 30CrMo Steel.

In order to enhance the quality of diamond composite materials, this work employs a Cu-Co-Fe and Ni-Cr-Cu pre-alloyed powder mixture as a transition layer, and utilizes laser-welding technology for saw blade fabrication. By adjusting the laser-welding process parameters, including welding speed and welding power, well-formed welded joints were achieved, and the microstructure and mechanical properties of the welded joints were investigated. The results demonstrate that the best welding performance was achieved at a laser power of 1600 W and a welding speed of 1400 mm/min, with a remarkable tooth engagement strength of up to 819 MPa. The fusion zone can be divided into rich Cu phase and rich Fe phase regions, characterized by coarse grains without apparent preferred orientation. The microstructure of the heat-affected zone primarily consists of high-hardness brittle quenched needle-like martensite, exhibiting a sharp increase in microhardness up to 550 HV. Fracture occurred at the boundary between the fusion zone and the heat-affected zone of the base material, where stress concentration was observed. By adjusting the welding parameters and transition layer materials, the mechanical properties of the joints were improved, thereby achieving a reliable connection between diamond composite materials and the metal substrate.

Laser Shock Peening: Fundamentals and Mechanisms of Metallic Material Wear Resistance Improvement.

With the rapid development of the advanced manufacturing industry, equipment requirements are becoming increasingly stringent. Since metallic materials often present failure problems resulting from wear due to extreme service conditions, researchers have developed various methods to improve their properties. Laser shock peening (LSP) is a highly efficacious mechanical surface modification technique utilized to enhance the microstructure of the near-surface layer of metallic materials, which improves mechanical properties such as wear resistance and solves failure problems. In this work, we summarize the fundamental principles of LSP and laser-induced plasma shock waves, along with the development of this technique. In addition, exemplary cases of LSP treatment used for wear resistance improvement in metallic materials of various nature, including conventional metallic materials, laser additively manufactured parts, and laser cladding coatings, are outlined in detail. We further discuss the mechanism by which the microhardness enhancement, grain refinement, and beneficial residual stress are imparted to metallic materials by using LSP treatment, resulting in a significant improvement in wear resistance. This work serves as an important reference for researchers to further explore the fundamentals and the metallic material wear resistance enhancement mechanism of LSP.

Ginsenoside Rg1 exerts anti­apoptotic effects on non­alcoholic fatty liver cells by downregulating the expression of SGPL1.

Non­alcoholic fatty liver disease (NAFLD) has a high incidence, and can lead to liver cirrhosis and even hepatocellular carcinoma in severe cases. To the best of our knowledge, there is currently no safe and effective treatment for the management of this disease. Ginsenoside Rg1 (Rg1) is an active monomer derived from ginseng and notoginseng. In the present study, HHL­5 hepatocytes were used to establish an in vitro cell model of NAFLD by medium­ and long­chain fat emulsion treatment, and the effects of Rg1 on adipose accumulation, apoptosis and the expression levels of apoptosis­related proteins in HHL­5 hepatocytes were examined. The results demonstrated that Rg1 inhibited the accumulation of fat in HHL­5 cells, while inhibiting apoptosis, and Rg1 downregulated the expression levels of the pro­apoptotic protein Bax and upregulated the expression levels of the anti­apoptotic protein Bcl­2, indicating that Rg1 could promote the stability or integrity of mitochondria and exert an anti­apoptotic effect by regulating Bcl­2 family proteins. In addition, Rg1 markedly downregulated the expression levels of sphingosine­1­phosphate lyase 1 (SGPL1), a key enzyme in the sphingosine signaling pathway, in HHL­5 cells with steatosis, and increased the expression levels of the downstream pro­survival signals phosphorylated (p­)Akt and p­Erk1/2. Furthermore, overexpression of SGPL1 abolished the anti­apoptotic effect of Rg1 on SGPL1­overexpressing HHL­5 cells with steatosis, and downregulated the expression levels of pro­survival proteins, such as Bcl­2, p­Akt and p­Erk1/2, whereas the expression levels of pro­apoptotic Bax were markedly increased. In conclusion, although there are some reports regarding the protective effect of Rg1 on fatty liver cells, to the best of our knowledge, the present study is the first to report that Rg1 may exert an anti­apoptotic effect on fatty liver cells by regulating SGPL1 in the sphingosine signaling pathway. Rg1 is the main component of the prescription drug Xuesaitong in China; therefore, the findings of the present study may provide a theoretical molecular basis for the use of Rg1 or Xuesaitong in the treatment of patients with NAFLD.