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Most of the molds of automobile panels are spliced with insert-type modules. Sudden variations in load and impact vibration can occur while processing splicing area, which affects the overall quality of this area. In this study, to improve the machining accuracy of the convex-surface splicing area, the influence of thermal deformation of tool, residual height, and impact vibrations on the machining error of this area is firstly analyzed. Subsequently, based on the motion path of the cutting edge of ball-end mill, a comprehensive error model for mill machine is established, which accounts for the tool error, residual height, and milling vibration. Finally, based on the milling experiment of convex-surface splicing die, the variation trend of machining error with machining inclination, spindle speed, and cutting depth is examined to verify comprehensive error algorithm MATLAB simulation results. The experimental results show that the prediction error of the proposed error model is between 4-8 % when the machining inclination is positive, and it is between 18-21 % when the machining inclination is negative, indicating that the proposed model is consistent with the experimental data. Novelty aspects, the present work: (i) proposes a mechanistic modeling approach to predicting machining error considering of thermal deformation, residual height, and impact vibrations for splicing mold; (ii) demonstrates that thermal deformation, residual height, and impact vibrations need to be taken into account for modeling the comprehensive machining error of splicing mold; (iii) contributes to practical industrial application of finishing machining technology of mold and die with splicing characteristics. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effect and mechanism of 17 β-estradiol (E2) on oxidative stress in the osteoblasts. An oxidative stress-induced damage model was established using H2O2 in MC3T3-E1 cells, and H2O2-induced cells were treated with E2. The results indicated that E2 attenuated oxidative stress in H2O2-induced MC3T3-E1 cells. In addition, H2O2 upregulated the expression of miR-320-3p and downregulated that of RUNX2, but these changes were counteracted by E2. Thereafter, we verified the interactive relationship between miR-320-3p and RUNX2. Then, H2O2-induced MC3T3-E1 cells were transfected with miR-320-3p mimics or inhibitors and treated with E2. The results indicated that miR-320-3p inhibition suppressed H2O2-induced inflammation, apoptosis, and oxidative stress and promoted the osteogenic differentiation of MC3T3-E1 cells by regulating RUNX2, ALP, and OCN, and this effect was further strengthened by E2. In conclusion, the findings suggest that E2 alleviates oxidative damage in osteoblasts by regulating the miR-320/RUNX2 signaling. [ABSTRACT FROM AUTHOR]

With the development of manufacturing fields such as automotive mold, the requirement for cutting tool with different structures and properties is constantly increasing. A parametric design method for double-arc milling cutter which is suitable for precision machining is proposed in this article. The tool rotation surface and cutting edge curves are provided. Effective cutting radius, cutting scallop-height, and curvature radius of tool surface are analyzed. The method for selecting tool parameters and feed direction is discussed. Five sets of double-arc milling cutters with different tool parameters are manufactured to verify the feasibility. An experiment is conducted to prove that machining quality can be improved by using double-arc milling cutter. This article provides a new method for tool parametric design and proposes a theoretical basis for better machining quality. [ABSTRACT FROM AUTHOR]

Double-arc milling cutter can effectively enhance the workpiece surface quality and is appropriate for finish machining complex surface. This article examines the effects of tool structure factor, two vertical milling orientations, workpiece inclination angle, cutting speed, and feed per tooth on the cutting force in order to thoroughly explore the cutting performance of double-arc milling cutter. Instantaneous effective cutting speed and radius models are established for various cutting orientations and conditions using the parameterized model of double-arc milling cutter. Additionally, a method for characterizing the tool structure factor of double-arc milling cutter is proposed. Three double-arc milling cutters with different structure factor and single factor experiments for milling concave and convex surfaces are designed. The impact of tool structure factor, workpiece inclination angle, cutting orientations, and cutting parameters on cutting force is thoroughly analyzed. Theoretical support is provided for the optimization of tool parameters, cutting orientations, and cutting parameters prior to surface machining. [ABSTRACT FROM AUTHOR]

Semiconductor nanoholes have garnered significant interest due to their unique nanotopological structures, which can result in distinct physicochemical characteristics. This study delves into the properties of crystal vibrations in nanohole structures. The analytic Fröhlich phonon state and dispersion relationship in wurtzite nanoholes, with circular and square cross sections (CS), are derived using the macroscopic dielectric continuum model. It is found that two types of phonon modes, surface optical (SO) and half‐space (HS) modes, coexist in wurtzite nitride nanohole structures. These phonon modes and their dispersive behaviors in nanoholes significantly differ from those in nanowires due to the different nanotopological structures. Furthermore, the Fröhlich electron–phonon interaction Hamiltonians for SO and HS phonon modes in nanoholes are obtained based on a field quantization scheme. Numerical calculations on wurtzite AlN nanoholes reveal that the shape of the CS has a remarkable influence on the dispersive spectra of SO and HS phonon modes. Additionally, it is found that the dielectric medium significantly affects the dispersive features of SO modes, while its influence on the dispersive behavior of HS modes is negligible. The profound physical mechanisms behind these observations are deeply analyzed. [ABSTRACT FROM AUTHOR]

Summary: Objectives Cardamonin (CD), an active chalconoid, has been extensively studied in a wide variety of human tumors. However, the effects and underlying mechanism of cardamonin on 5-fluorouracil (5-FU)-resistant gastric cancer (GC) remain largely unclear. This study aimed to investigate the antitumor effects of cardamonin on 5-FU-resistant GC cells and explore the molecular mechanisms underlying its therapeutic potential. Methods The antitumor activities of cardamonin, 5-FU and their combination against BGC-823 and BGC-823/5-FU cells were determined using cytotoxicity assay, flow cytometry-based cell cycle analysis and Annexin V apoptosis assay. The effect of cardamonin on P-glycoprotein activity was assessed by Rh123 uptake assay. Real-time PCR, Western blotting and Co-immunoprecipitation analysis were carried out to assess the inhibition of Wnt/β-catenin signaling pathway. A xenograft mouse model was established using BALB/c nude mice to examine the combinatorial effects of cardamonin and 5-FU on tumor growth. Results Our data provided the first demonstration that cardamonin significantly enhanced the chemosensitivity of 5-FU in GC cells via suppression of Wnt/β-catenin signaling pathway. Additionally, the combination of cardamonin and 5-FU might result in the apoptosis and cell cycle arrest of BGC-823/5-FU cells, accompanied by the downregulated expression levels of P-glycoprotein, β-catenin and TCF4. More importantly, our results demonstrated that cardamonin specifically disrupted the formation of β-catenin/TCF4 complex, leading to TCF4-mediated transcriptional activation in 5-FU-resistant GC cells. Besides, through a xenograft mouse model, co-administration of cardamonin and 5-FU significantly retarded tumor growth in vivo, thus, confirming our in vitro findings. Conclusions Overall, this study revealed that cotreatment of cardamonin and 5-FU could strongly potentiate the antitumor activity of 5-FU, and put forth cardamonin as a rational therapeutic strategy for drug-resistant GC treatment. [ABSTRACT FROM AUTHOR]