Effect of Different Cooling Rates in High Rheological Rate Forming Process on Mechanical Properties of Zr57Cu20Al10Ni8Ag5 Bulk Metallic Glass

Xiao‑Bo Mei,Bao‑Chuan Liu,Wei Jiang,Quan Xu,Qi‑Dong Zhang,Yu‑Bai Ma,Fang‑Qiu Zu 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

The influence of cooling rates on the mechanical properties of a Zr-based bulk metallic glass prepared with high rheologicalrate forming (HRRF) was investigated and compared with traditional suction cast methods. Amorphous samples of Zr57Cu-20Ni8Al10Ag5 were prepared in copper molds with different sizes in order to obtain different cooling rates for both HRRFand traditional cast methods. These specimens were subjected to compression experiments, including microhardness testing,X-ray diffraction testing and differential scanning calorimetry analysis. The results indicate that the plasticity of the samplesformed by HRRF are higher than that of the as-cast ones at the same cooling rates, while the microhardness manifests theopposite principle. As the cooling rate increases further, the difference in plasticity further increases between two methods,indicating that the plasticity of metallic glasses is more sensitive to cooling rates during the HRRF process. At the core ofthis phenomenon is the fact that HRRF methods can introduce more free volume into glasses than traditional cast methodswith an elevated cooling rate are able to.

The Delay-dependent Absolute Stability Condition for T-S Fuzzy Lurie Control Systems with Time-varying Delay

Xiao-Xu Xia 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.10

In this paper, the problem of delay-dependent absolute stability condition for a new class of Takagi-Sugeno (T-S) fuzzy Lurie control systems with time-varying delay is investigated. New Lyapunov functions are defined by utilizing the Lyapunov-Krasovskii functional (LKF). Meanwhile, free-weighting matrix method and some techniques are used to obtain a new absolute stability condition, which is different from previous research. Finally, a numerical example will be provided to demonstrate feasibility and less conservativeness of the proposed result.

The Delay-dependent Condition for Uncertain T-S Fuzzy Lurie Control Systems with Time-delay

Xiao-Xu Xia 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.5

The problem of delay-dependent condition for a new class of Takagi-Sugeno (T-S) fuzzy Lurie control systems with time-delay and time-variant uncertainties is investigated in this paper, which is different from existing ones. We use T-S fuzzy models to describe Lurie system in the form of a weighted sum of some simple linear subsystems, and a new delay-dependent absolute stability criterion for such systems is derived by utilizing Lyapunov-Krasovskii functional (LKF), linear matrix inequality (LMI) approach and novel techniques. Finally, a numerical example and its simulation results have shown that the proposed result is feasible and effective.

Signal processing method based on energy ratio for detecting leakage of SG using EVFM

Xu Wei,Xu Ke-Jun,Yan Xiao-Xue,Yu Xin-Long,Wu Jian-Ping,Xiong Wei 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

FBXL20-mediated Vps34 ubiquitination as a p53 controlled checkpoint in regulating autophagy and receptor degradation

Xiao, Juan,Zhang, Tao,Xu, Daichao,Wang, Huibing,Cai, Yu,Jin, Taijie,Liu, Min,Jin, Mingzhi,Wu, Kejia,Yuan, Junying Cold Spring Harbor Laboratory Press 2015 Genes & development Vol.29 No.2

<P>Vps34, the catalytic subunit in the class III phosphatidylinositol 3 kinase complexes, mediates the production of PtdIns3P, a key intracellular lipid involved in regulating autophagy and receptor degradation. Xiao et al. show that DNA damage-activated mitotic arrest and CDK activation lead to the phosphorylation of Vps34. This provides a signal to promote Vps34 ubiquitination and proteasomal degradation mediated by FBXL20, leading to inhibition of autophagy and receptor endocytosis. Importantly, they also find that expression of FBXL20 is regulated by p53-dependent transcription.</P><P>Vacuolar protein-sorting 34 (Vps34), the catalytic subunit in the class III PtdIns3 (phosphatidylinositol 3) kinase complexes, mediates the production of PtdIns3P, a key intracellular lipid involved in regulating autophagy and receptor degradation. However, the signal transduction pathways by which extracellular signals regulate Vps34 complexes and the downstream cellular mechanisms are not well understood. Here we show that DNA damage-activated mitotic arrest and CDK activation lead to the phosphorylation of Vps34, which provides a signal to promote its ubiquitination and proteasomal degradation mediated by FBXL20 (an F-box protein) and the associated Skp1 (S-phase kinase-associated protein-1)–Cullin1 complex, leading to inhibition of autophagy and receptor endocytosis. Furthermore, we show that the expression of FBXL20 is regulated by p53-dependent transcription. Our study provides a molecular pathway by which DNA damage regulates Vps34 complexes and its downstream mechanisms, including autophagy and receptor endocytosis, through SCF (Skp1–Cul1–F-box)-mediated ubiquitination and degradation. Since the expression of FBXL20 is regulated by p53-dependent transcription, the control of Vps34 ubiquitination and proteasomal degradation by FBXL20 and the associated SCF complex expression provides a novel checkpoint for p53 to regulate autophagy and receptor degradation in DNA damage response.</P>

The effect of pre- and after-treatment of sevoflurane on central ischemia tolerance and the underlying mechanisms

Xu, Hao,Mei, Xiao-Peng,Xu, Li-Xian The Korean Dental Society of Anesthsiology 2018 Journal of Dental Anesthesia and Pain Medicine Vol.18 No.1

In recent years, with continuous research efforts targeted at studying the effects of pre- and after-treatment of inhaled anesthetics, significant progress has been made regarding the common clinical use of low concentrations of inhaled sevoflurane and its effect on induced central ischemia tolerance by pre- and post-treatment. In this study, we collected, analyzed, classified, and summarized recent literature regarding the effect of sevoflurane on central ischemia tolerance and its related mechanisms. In addition, we provide a theoretical basis for the clinical application of sevoflurane to protect the central nervous system and other important organs against ischemic injury.

Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling

Xu, Sheng,Yan, Zheng,Jang, Kyung-In,Huang, Wen,Fu, Haoran,Kim, Jeonghyun,Wei, Zijun,Flavin, Matthew,McCracken, Joselle,Wang, Renhan,Badea, Adina,Liu, Yuhao,Xiao, Dongqing,Zhou, Guoyan,Lee, Jungwoo,Chu American Association for the Advancement of Scienc 2015 Science Vol.347 No.6218

<P><B>Popping materials and devices from 2D into 3D</B></P><P>Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu <I>et al.</I> develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape.</P><P><I>Science</I>, this issue p. 154; see also p. 130</P><P>Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations.</P>

Metabolomic analysis of biochemical changes in the tissue and urine of proteoglycan-induced spondylitis in mice after treatment with moxibustion

Xiao Xu,Ya-Nan Shi,Rong-Yun Wang,Cai-Yan Ding,Xiao Zhou,Yu-Fei Zhang,Zhi-Ling Sun,Zhi-Qin Sun,Qiu-Hua Sun 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.1

Background: Moxibustion is widely used in East Asian countries to manage the symptom of rheumatic diseases. The aim of this study was to identify potential metabolic profiles of moxibustion on relieving ankylosing spondylitis (AS) mice through UHPLC-Q-TOF/MS metabolomic study. Methods: Thirty-two female Balb/c mice were randomized into healthy control (HC), AS model, moxibustion at acupuncture points (MA) in AS model, and moxibustion at non-acupuncture points (MNA) AS model groups. Moxibustion was administered daily at GV4, bilateral BL23 and bilateral ST36 acupuncture points for four weeks in the MA group. The overall health status, the thickness of hind paws and the tissue concentrations of IL-1β, PGE2, IL-6 and TNF-α were assessed. The UHPLC-Q-TOF/MS was used to explore the perturbations of endogenous metabolites in tissue and urine of AS model mice intervened by moxibustion. Results: Compared with the AS group, the overall health status was significantly improved after 4-week moxibustion intervention (p < 0.05). The results also showed that MA significantly reduced the levels of paw thickness and decreased the levels of four cytokines in the tissue (p < 0.01). Thirty-seven endogenous metabolites identified by the OPLS-DA were considered to be contributing to therapeutic effects of moxibustion. Moreover, metabolic pathway analysis further revealed that the identified metabolites were mainly involved in TCA cycle, Lipid metabolism, Amino Acid metabolism, Intestinal flora metabolism and Purine metabolism. Conclusions: UHPLC-Q-TOF/MS based metabolomics approach, as a novel and powerful tool, can help us to gain the insights into potential mechanisms of action of moxibustion for AS.

Autophagy in Tumorigenesis and Cancer Treatment

Xu, Dong-Wei,Zhang, Guan-Qing,Wang, Zong-Wei,Xu, Xiao-Yin,Liu, Tong-Xiang Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.6

Autophagy is a self-digestion process, wrapping cytoplasmic proteins or organelles to form vesicles for degradation in lysosomes. The process plays an important role in the maintenance of intracellular homostasis. Here we overview articles on autophagy and cancer/tumors in Pubmed and found 327 articles. Autophagy exists in many tumors and is involved in cell malignant transformation and tumor cell growth. In early phases of tumorigenesis, autophagy clears the abnormally folded proteins and dysfunctional organelles such as mitochondria. Autophagy can also inhibit cell stress responses and prevent genetic damage. When a tumor develops, autophagy helps tumor cells survive nutritional deficiencies and hypoxic conditions. Studies of autophagy in the occurrence and progression of tumors should provide new therapeutic strategies for tumors.

Adsorption of Nucleotides on ${\beta}$-Cyclodextrin Derivative Grafted Chitosan

Xiao Jian-Bo,Yu Hong-Zhu,Xu Ming,Chen Xiao-Qing The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.4

A novel ${\beta}$-cyclodextrin derivative (CCD-C) was synthesized with chitosan and carboxymethyl-${\beta}$-cyclodextrin. Its structure was characterized by elemental analysis, infrared spectra analysis, and X-ray diffraction analysis. The adsorption properties for guanosine 5'-monophosphate, cytidine 5'-monophosphate and uridine 5'-monophosphate were studied. Experimental results demonstrated that CCD-C had higher adsorption capability for guanosine 5'-monophosphate, and that the adsorption capacity for guanosine 5'-monophosphate was 74.20mg/g. The adsorption capacity was greatly influenced by pH, time and temperature. The introduction of chitosan enhanced the adsorption ability and adsorption selectivity of ${\beta}$-cyclodextrin for guanosine 5'-monophosphate. This novel derivative of chitosan is expected to have wide applications in the separation, concentration and analysis of nucleotides in biological samples.