Laser Ablation Applications in Ablation-Resistance Characterization of Materials

Owing to the rapid heating and large power intensity, the laser beams were successfully used to characterize the ablation-resistant performance of materials, which provided us more knowledge about the usability of materials in the ablation environment and developing protection against laser irradiation. In this chapter, we comparatively introduced some experimental methods for ablation-resistance characterization of materials. The fundamentals of laser-material interactions were discussed from the physical and chemical aspects to help understand the laser ablation mechanism. Finally, we presented some practical applications of laser ablation in ablation-resistance characterization of ultra-high-temperature ceramics (UHTCs) and ceramic matrix composites and discussed the laser ablation behavior and mechanism

Effect of infiltration time on the microstructure and mechanical properties of C/C-SiC composite prepared by Si‐Zr10 alloyed melt infiltration

Low cost C/C-SiC composites were prepared through reactive melt infiltration with Si-Zr10 alloy infiltrant under different infiltration time. Effect of infiltration time on the microstructure and mechanical properties of the composite were investigated. ZrC tended to be formed in the composite and the amount of carbon phase decreased with an extension in the infiltration time according to the X-ray diffraction results. Phase transformation of the C/C-SiC composite was analyzed based on C-Si-Zr phase diagram. Flexural strength of the composite prepared by preform 0.9 g/cm³ decreased with an increase in the infiltration time while that of the composite prepared by preform 1.38 g/cm³ increased initially and then decreased reversely. The highest flexural strength of the composite was found at about 324 MPa. Flexural strength of the composite is considered to depend on its phase composition and fiber-matrix interface.This work was supported by National Natural Science Foundation of China (51302315), Innovation Foundation for Excellent Postgraduate of National University of Defense Technology and Hunan Provincial Innovation Foundation for Postgraduate. Yonggang Tong also thanks the support from China Scholarship Council

Laser ablation resistance and mechanism of Si-Zr alloyed melt infiltrated C/C-SiC composite

Ablation resistance of C/C-SiC composite prepared via Si-Zr alloyed reactive melt infiltration was evaluated using a facile and economical laser ablation method. Linear ablation rates of the composite increased with an increase in laser power densities and decreased with extended ablation time. The C/C-SiC composite prepared via Si-Zr alloyed melt infiltration presented much better ablation resistance compared with the C/SiC composite prepared by polymer infiltration and pyrolysis process. The good ablation resistance of the composite was attributed to the melted ZrC layer formed at the ablation center region. Microstructure and phase composition of different ablated region were investigated by SEM and EDS, and a laser ablation model was finally proposed based on the testing results and microstructure characterization. Laser ablation of the composite experienced three distinct periods. At the very beginning, the laser ablation was dominated by the oxidation process. Then for the second period, the laser ablation was dominated by the evaporation, decomposition and sublimation process. With the further ablation of the composite, chemical stable ZrC was formed on the ablated surface and the laser ablation was synergistically controlled by the scouring away of ZrC melts and evaporation, decomposition and sublimation process.This work is supported by National Natural Science Foundation of China (51641502)

Theoretical model and practical exploration of digital technology-empowered green management of water resource in semiconductor manufacturing industry

[Objective] This study focused on the green management of water resources in the semiconductor manufacturing industry based on digital technology. It analyzed the establishment of a comprehensive framework for green management of water resources from the perspective of technological empowerment, providing theoretical paradigm and practical guidance for the application of digital technology and the green development in the semiconductor manufacturing industry. [Methods] By systematically reviewing relevant literature on the domestic and international levels and incorporating multidisciplinary solutions, an innovative circular economy model was constructed. The article established a water resource green intelligent management system for semiconductor manufacturing enterprises, and used a case study method to select a typical semiconductor manufacturing enterprise, then deeply analyzed the application process of the technological framework. [Results] (1) Based on the “reduction, reuse, recycle” 3R principle of the circular economy model, and utilized the systematic analysis method, a theoretical model for the digital technology-empowered green management of water resources framework was built. (2) The theoretical model explained the connotation, characteristics, and functions of digital technology empowerment from the source to the end of each production process. It analyzed the specific measures of each enterprise under the 3R principle, and revealed the action path of data technology in empowering green management of water resources. (3) Through a case study of a semiconductor company in East China, the practical exploration of intelligent water resources green management technology solutions was achieved. The trend of data change over the past three years indicated a basic positive correlation between digital technology innovation and the benefits of green management of water resources, with higher benefits corresponding to higher innovation levels. [Conclusion] Digital technology can provide innovative green water resources management solutions for semiconductor manufacturing companies, enhancing their competitiveness. For the new development stage of the Chinese semiconductor manufacturing industry, it has significant implications for strengthening the dominant position of digital technology innovation and improving intelligent green management of water resources

Stem cell factor SALL4, a potential prognostic marker for myelodysplastic syndromes

Background: Myelodysplastic syndromes (MDS) are a group of heterogeneous diseases with variable clinical course. Predicting disease progression is difficult due to lack of specific molecular marker(s). SALL4 plays important roles in normal hematopoiesis and leukemogenesis. SALL4 transgenic mice develop MDS prior to acute myeloid leukemia (AML) transformation. However, the role of SALL4 in human MDS has not been extensively investigated. In this study, we evaluate the diagnostic/prognostic value of SALL4 in MDS by examining its expression levels in a cohort of MDS patients. Methods: Fifty-five newly diagnosed MDS, twenty MDS-AML, and sixteen post-treatment MDS patients were selected for our study along with ten healthy donors. Results: We demonstrated that SALL4 was over-expressed in MDS patients and proportionally increased in MDS patients with high grade/IPSS scores. This expression pattern was similar to that of Bmi-1, an important marker in predicting MDS/AML progression. In addition, the level of SALL4 was positively correlated with increased blast counts, high-risk keryotypes and increased significantly in MDS-AML transformation. Furthermore, higher level of SALL4 expression was associated with worse survival rates and SALL4 level decreased following effective therapy. Conclusions: To the best of our knowledge, this is the largest series and the first to report the expression pattern of SALL4 in detail in various subtypes of MDS in comparison to that of Bmi-1. We conclude that SALL4 is a potential molecular marker in predicting the prognosis of MDS

Cooperation-based sperm clusters mediate sperm oviduct entry and fertilization

Sperm cooperation has been observed in multiple species, yet its existence and benefit for reproductive success in mammals remains underexplored. Here, combining tissue-clearing with deep three-dimensional imaging, we demonstrate that postcopulatory mouse sperm congregate into unidirectional sperm cooperative clusters at the utero-tubal junction (UTJ), a key physical barrier for passage into the oviduct. Reducing sperm number in male mice by unilateral vasoligation or busulfan-treatment impairs sperm cluster formation and oviduct entry. Interestingly, sperm derived from Tex101-/- mouse has normal number, motility and morphology, yet they cannot form sperm cluster and fail to pass through the UTJ, which is at least in part due to the altered tail beating pattern of the Tex101-/- sperm. Moreover, Tex101-/- sperm's defect in oviduct entry cannot be rescued by the presence of wild-type (WT) sperm in the same uteri by sequential mating, suggesting sperm cooperative cluster as an essential behavior contributing to male fertility, which could be related to human infertility or subfertility

The insertion/deletion (I/D) polymorphism in the Angiotensin-converting enzyme gene and cancer risk: a meta-analysis

<p>Abstract</p> <p>Background</p> <p>The insertion/deletion (I/D) polymorphism in the <it>Angiotensin-converting enzyme </it>(<it>ACE</it>) gene has been implicated in susceptibility to cancer, but a large number of studies have reported inconclusive results. The aim of this study is to assess the association between the I/D polymorphism in the <it>ACE </it>gene and cancer risk by meta-analysis.</p> <p>Methods</p> <p>A search was performed in Pubmed database, Embase database, Chinese Biomedical (CBM) database, China National Knowledge Infrastructure (CNKI) database and Weipu database, covering all studies until August 31, 2010. Statistical analysis was performed by using Revman4.2 and STATA 10.0.</p> <p>Results</p> <p>A total of 25 case-control studies comprising 3914 cancer patients and 11391 controls were identified. No significant association was found between the I/D polymorphism and over all cancer risks (OR = 0.88, 95%CI = 0.73-1.06, P = 0.17 for DD+DI vs. II). In the subgroup analysis by ethnicity, no significant association was found among Asians and Europeans for the comparison of DD+DI vs. II. In the subgroup analysis by cancer types, no significant associations were found among lung cancer, breast cancer, prostate cancer, colorectal cancer, gastric cancer for the comparison of DD+DI vs. II. Results from other comparative genetic models also indicated the lack of associations between this polymorphism and cancer risks.</p> <p>Conclusions</p> <p>This meta-analysis suggested that the <it>ACE </it>D/I polymorphism might not contribute to the risk of cancer.</p