Detecting the origin of luminescence in Er³⁺-doped hexagonal Na_1.5Gd_1.5F₆ phosphors

Wang, Xiangfu,Bu, Yanyan,Yan, Xiaohong,Cai, Peiqing,Wang, Jing,Qin, Lin,Vu, Thiquynh,Seo, Hyo Jin OPTICAL SOCIETY OF AMERICA 2016 Optics letters Vol.41 No.22

<P>Understanding site-selective fluorescence is one of valuable importance for spectrum modulation. In this Letter, we observed the existence of two non-equivalent Gd-activated crystallographic sites in an Er3+-doped hexagonal Na1.5Gd1.5F6 phosphor. It is proved that two green emissions from the S-4(3/2) level separately originate from the Gd1 (540 nm) and Na2/Gd2 (550-555 nm) crystallographic sites, and the 657 nm red emission from the F-4(9/2) level only originates from Na2/Gd2 site through using the time-resolved luminescence spectra. The 142.2% absolute enhancement of the red emission is realized through the synergistic effect of ultraviolet downconversion and infrared upconversion induced by the 370 nm and 1.54 mu m dual-mode excitation. (C) 2016 Optical Society of America</P>

A review of experimental methods for characterising composite viscosities of continuous fibre-reinforced polymer composites

Wang Jinhuo,Han Yang,Ge Xiaohong,Qi Zhengbing,Zhao Jun,Wang Rongwen,Wu Huawei,Han Taiping,Sun Shaoxun,Wang Hui,Lin Jia,Liu Yuejun,Kong Xiangsong,Chen Qiming,Zeng Xiangxu 한국유변학회 2023 Korea-Australia rheology journal Vol.35 No.2

Optimisation design of composite structures requires an accurate predictive model for forming behaviour. The simulation process contains a number of model parameters which include transverse and longitudinal viscosities of continuous fibrereinforced viscous composites, fundamental to predicting the shear rheology. Shearing the unidirectional composite along the fibre direction gives a measure of the longitudinal viscosity (LV), whilst shearing across or transverse to the fibre direction gives a measure of the transverse viscosity (TV). Numerous experimental work was conducted in the past to measure these two viscosities for various materials. However, conflicting measurements by different test methods were obtained and these apparent discrepancies had not yet been systematically investigated in any single study. This paper reviews previous work on characterisation techniques to further understand the cause of such discrepancy, and hence to improve measurement accuracy, which would benefit future work on theoretical modelling of the composite viscosities and optimisation simulation of composites forming. Some important findings, such as effects of resin-rich areas, contributory factors of elastic effects, non-Newtonian behaviour for composites with Newtonian matrix, aspect ratio and end effects of test samples, geometry effects of fibres and fibre rearrangement during shearing, existence of a mathematical relationship between LV and TV and necessary benchmarking exercise using Newtonian matrix composites, were summarised.

A novel semi-IPN hydrogel: Preparation, swelling properties and adsorption studies of Co (II)

Xiaohong Wang,Haiqian Hou,Yujun Li,Yingying Wang,Chen Hao,Cunwang Ge b 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.41 No.-

A range of super-absorbent semi-IPN hydrogels—polyvinyl alcohol/poly (acrylic acid-co-acrylic amide)(PVA-P(AA-co-AM)) were synthesized via free radical polymerization method under ultrasound-assistedcondition. L16 (45) orthogonal experiments were designed to optimize the synthesis conditions and thesuccess was characterized by FTIR, SEM and TGA. Swelling capacities were studied in various pH solutionand saline solution whose results indicated that pH in solution shows an obvious influence on it and thesalt resistance is greater in salt solution of low valence relative to that of high valence. Meanwhile, itsswelling behavior was evaluated in water solution, which revealed that the swelling process conformedto the Schott model and the diffusion type was non-Fickian diffusion. Moreover, the adsorption on cobalt(II) from aqueous solutions was also investigated in the paper. The optimumpH value was found close to4 for the cobalt (II) adsorption and it was discovered that adsorption kinetics and adsorption isothermsfor cobalt (II) were in accordance with the pseudo-second-order model and the Freundlich modelrespectively. Besides, thermodynamic parameters were calculated for the cobalt (II) adsorption and thefindings revealed that the adsorption behavior is spontaneous and endothermic.

Experimental Study of Horizontal Gas-liquid Two-phase Flow in Two Medium-diameter Pipes and Prediction of Pressure Drop through BP Neural Networks

Wang Qinghua,Zou Honglan,Luo Wei,Yang Junzheng,Wen Xiaohong,Wang Yan 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3

Horizontal gas-liquid two-phase flow is of crucial importance in oil-gas storage and transportation. In view of previous researches with the lack of horizontal gas-liquid two-phase flow in medium-diameter pipes (60-75 ㎜), experiments were conducted in DN 60 and DN75 at medium-high liquid velocity (50-250 m3/d) and high gas-liquid ratio (20-500 m3/m3). Comparison between flow patterns maps in DN60 and DN75 and the Taitel-Dukler model showed that only flow patterns map in DN60 agreed well. On the basis of experimental data analysis, variation laws of liquid holdup and pressure drop were determined. Besides, this paper developed a method to predict liquid holdup and pressure drop through BP neural networks. Results proved the capability of BP neural networks. The further validation can be made in practical applications.

Enhanced Global Asymptotic Stabilization Criteria for Delayed Fractional Complex-valued Neural Networks with Parameter Uncertainty

Xiaohong Wang,Zhen Wang,Yingjie Fan,Jianwei Xia,Hao Shen 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.4

This paper addresses the global asymptotic stabilization of delayed fractional complex-valued neural networks(FCVNNs) subject to bounded parameter uncertainty. The problem is proposed for two reasons: 1) The availablemethods for uncertain dynamical systems may be too conservative; 2) The existing algebraic conditions willlead to huge computational burden for large-scale FCVNNs. To surmount these difficulties, the delayed FCVNNswith interval parameters are transformed into a tractable form at first. Then, a simple and practical controller–linearstate feedback controller is designed to achieve the global asymptotic stabilization. By constructing different Lyapunovfunctions and utilizing the fractional-order comparison principle and interval matrix method, two sufficientglobal asymptotic stabilization criteria expressed in LMI forms, are established. The obtained results in this paperimprove and extend some previous published results on FCVNNs. Finally, two numerical examples are provided toillustrate the correctness of the theoretical results.

Z-domain modeling of peak current mode control for full-bridge DC-DC buck converters

Wang, Xiaohong,Huang, Qisong,Zhang, Bo,Chen, Di,Guan, Quanxue The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

Traditional local-averaged state-space modeling for peak current mode (PCM) controls fails to explain the subharmonic oscillation phenomenon when the spectrum is higher than half of the switching frequency. To address this problem, this paper presents a small-signal modeling method in the z-domain, and builds a discrete linear model for the current loop of a full-bridge DC-DC converter. This discrete model is converted into a second-order continuous model that is able to represent the system performance with a wider frequency range. A frequency-domain analysis shows that this model can be used to explain the subharmonic oscillations and unstable characteristics. This provides an engineering guideline for the practical design of slope compensation. The effectiveness of the proposed modeling method has been verified by simulation and experimental results with a prototype working in the Buck mode.

Microstructure, Thermal Behavior and Tensile Properties of Laser Welded Bottom-Locking Joint for TA15 Titanium Alloy

Jiayao Wang,Jianfeng Wang,Yanqiu Zhao,Yue Li,Xiaohong Zhan 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

The present investigation aims at the thermal conditions for the TA15 titanium alloy laser welded bottom-locking joint. Bottom-locking featured specimens under three welding speeds were manufactured to study the grain morphology and tensileproperties. Finite element computation based on temperature field simulation was conducted in order to shed more light on themicrostructure characteristics of the bottom-locking joint. The results indicate a significant influence of the welding speed onthe thermal cycle, microstructure evolution and tensile performance. As the welding speed increases, the width of weld zone(WZ) is decreased significantly. At the same time, the columnar crystal features a coarser shape and its growth cross regionat the bottom of WZ becomes smaller with the increasing welding speed. Besides, the size of martensite decreases with theincreasing of welding speed. With the support of both numerical and experimental results, complex microstructure evolutionmechanisms were revealed involving thermal cycle related to the welding speed. In addition, the laser welded bottom-lockingjoint of TA15 titanium alloy is even fractured at the base metal, which exhibits the comparable tensile properties. The EDSresults illustrate the inevitable burning losses of stabilization element during the welding process. All these mechanisms areassociated with the bottom-locking joint arrangement and the welding speed-induced thermal cycle.

Synthesis of aminated calcium lignosulfonate and its adsorption properties for azo dyes

Yingying Wang,Linli Zhu,Xiaohong Wang,Wanru Zheng,Chen Hao,Chenglong Jiang,Jingbo Wu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-

A low-cost adsorbent, aminated calcium lignosulfonate (ACLS) was prepared and successfully applied to the adsorption of Congo red and the Titan yellow dyes. The adsorbent was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), elemental mapping images (EMIs) and Brunauer–Emmett–Teller (BET) analysis. And the efficiency of ACLS for the removal of Congo red and the Titan yellow dyes was evaluated by several factors, such as temperature, pH, adsorbent dose, contact time and initial concentration of dyes solution. And the test ranges of temperature, pH, adsorbent dose, contact time and initial concentration of dye solution were 25–45 °C, 2–12, 0.005–0.05 g, 1–48 h, 10–200 mg L−1, respectively. The adsorption results demonstrated a good ability to remove dye with the removal rates of 97% and 91% for 30 mg L−1 Congo red and 40 mg L−1 Titan yellow, respectively. The adsorption kinetic and adsorption isotherms can be well described by the pseudo second order kinetic and the Langmuir isotherm model for the both dyes, respectively. Moreover, the maximum adsorption capacity of Congo red and Titan yellow reached 258.4 mg g−1 and 190.1 mg g−1 in the study of the Langmuir adsorption isotherm, respectively. Thermodynamic studies show that the adsorption of the two dyes is a spontaneous endothermic process. The results indicate that the ACLS has the potential to be used in the treatment of dye wastewater.

Triptolide inhibits ovarian cancer cell invasion by repression of matrix metalloproteinase 7 and 19 and upregulation of E-cadherin

Hongxi Zhao,Zhifu Yang,Xiaohong Wang,Xianzhi Zhang,Meng Wang,Yukun Wang,Qibing Mei,Zhipeng Wang 생화학분자생물학회 2012 Experimental and molecular medicine Vol.44 No.11

Triptolide, a compound extracted from the traditional Chinese medicine preparation of Tripterygium wilfordii Hook F., has been reported to have anti-inflammatory and anti-cancer activities. However, its effect on ovarian cancer invasion is unknown. We observed that MMP7 and MMP19 expression increased in ovarian cancer tissue. Triptolide treatment inhibited the migration and invasion of ovarian cancer cells SKOV3 and A2780 at the concentration of 15 nM. We also observed that triptolide suppressed MMP7 and MMP19 promoter activity in a dose-dependent manner,down-regulating the expressions of these promoters on mRNA and protein level. Moreover, triptolide enhanced E-cadherin expression in ovarian cancer cells. In vivo, triptolide inhibited tumor formation and metastasis in nude mice, and suppressed MMP7 and MMP19 expression; it also enhanced E-cadherin expression in tumor in a dose-dependent manner. Over expression of MMP7 and MMP19, or suppression of E-cadherin expression partially abolished the inhibitory effect of triptolide on invasion of ovarian cancer cells. To summarize, triptolide significantly inhibited the migration and invasion of ovarian cancer cells by suppression of MMP7 and MMP19 and up-regulation of E-cadherin expression. This study shows that triptolide is a good candidate for the treatment of ovarian cancer and reduction of metastasis.

Changes in Protein Phosphorylation during Salivary Gland Degeneration in Haemaphysalis longicornis

Qi Xiao,Yuhong Hu,Xiaohong Yang,Jianna Tang,Xiaoshuang Wang,Xiaomin Xue,Mengxue Li,Minjing Wang,Yinan Zhao,Jingze Liu,Hui Wang 대한기생충학ㆍ열대의학회 2020 The Korean Journal of Parasitology Vol.58 No.2

The ticks feed large amount of blood from their hosts and transmit pathogens to the victims. The salivary gland plays an important role in the blood feeding. When the female ticks are near engorgement, the salivary gland gradually loses its functions and begins to rapidly degenerate. In this study, data-independent acquisition quantitative proteomics was used to study changes in the phosphorylation modification of proteins during salivary gland degeneration in Haemaphysalis longicornis. In this quantitative study, 400 phosphorylated proteins and 850 phosphorylation modification sites were identified. Trough RNA interference experiments, we found that among the proteins with changes in phosphorylation, apoptosis-promoting Hippo protein played a role in salivary gland degeneration.