Effect of heat shield on the thermal fields during sapphire crystal growth by Kyropoulos method

Yuqing Guo,Nannan Ge,Kai Wang,Meng Shen,Ming Wang 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.11

In this paper, the numerical computation was performed to investigate the influence of the heat shields of sapphire crystalfurnace on temperature distributions for the Kyropoulos sapphire crystal growth process. The heat shields with different shieldradius, shield layers and the shield materials were considered, the Kyropoulos growth process was simulated by the finiteelementmethod. It is found that radial temperature gradient of crystal would increase along with the increase of the shieldradius and the decrease of the layers of top shield. If properly increasing the shield radius and the layers of the top shield, axialtemperature gradient in crystal would decrease, but the layers of side shield have little influence on the temperature in crystal. The heat shields made of different materials were compared by analyzing the crystal temperature distribution. Simulationresults showed that temperature distribution in crystal by W-Mo shield is much closer to that of ZrO2 shield, both oftemperature distribution are higher than that of graphite heat shield.

Evaluation of the Differences of Myocardial Fibers between Acute and Chronic Myocardial Infarction: Application of Diffusion Tensor Magnetic Resonance Imaging in a Rhesus Monkey Model

Yuqing Wang,Wei Cai,Lei Wang,Rui Xia,Wei Chen,Jie Zheng,Fabao Gao 대한영상의학회 2016 Korean Journal of Radiology Vol.17 No.5

Objective: To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. Materials and Methods: Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). Results: Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 x 10-4 mm2/s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 x 10-4mm2/s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°–11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°–53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°–66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°–64.9 ± 4.3°). Conclusion: Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey’s models.

In situ Copolymerized Toughened Polymethyl Methacrylate (PMMA) with Highly Transparency for Support Film of Polarizers

Yingying Wang,Bin Yang,Liangyong He,Yuqing Yang,Nuo Zhang,Yang Wang,Zhiqiang Shi,Yuchao Ke,Lifen Su,Jia-Sheng Qian,RU XIA,Tao Jiang 한국고분자학회 2022 폴리머 Vol.46 No.5

In this study, a series of poly(methyl methacrylate) (PMMA) copolymer films were prepared via solutionpolymerization of methyl methacrylate (MMA) with butyl acrylate (BA) and lauryl methacrylate (LMA) as monomers. Mechanical properties, hydrophobic properties, and optical properties of the films were intensively investigated. The rheological results showed that the fluidity of the copolymer was considerably enhanced. When the monomer ratio ofMMA:BA:LMA was 100:30:10, the copolymer film S4 showed the best overall performance with perfect optical transparency maintained. The results of the dynamic mechanical and thermal analysis suggested that the glass transition temperature (Tg) moved towards lower temperature, with enhanced ductility of the PMMA films. A large number of yieldfolds and crazes appeared on the cross-sectional surface of copolymer films through morphological observations, displaying the obvious characteristics of toughness fracture and obeying the energy dissipation mechanism of cracks shearband. The present study provided a facile way of preparing PMMA films with high toughness and light transmittanceby appropriate selection of the monomers, which will be of practical significance for further studies on the replacementof triacetyl cellulose as a support film of polarizers.

A critical review of risks, characteristics, and treatment strategies for potentially toxic elements in wastewater from shale gas extraction

Sun, Yuqing,Wang, Di,Tsang, Daniel C.W.,Wang, Linling,Ok, Yong Sik,Feng, Yujie Pergamon 2019 Environment international Vol.125 No.-

<P><B>Abstract</B></P> <P>Shale gas extraction via horizontal drilling and hydraulic fracturing (HF) has enhanced gas production worldwide, which has altered global energy markets and reduced the prices of natural gas and oil. Water management has become the most challenging issue of HF, as it demands vast amounts of freshwater and generates high volumes of complex liquid wastes contaminated by diverse potentially toxic elements at variable rates. This critical review focuses on characterizing HF wastewater and establishing strategies to mitigate environmental impacts. High prioritization was given to the constituents with mean concentrations over 10 times greater than the maximum contamination level (MCL) guidelines for drinking water. A number of potentially harmful organic compounds in HF wastewaters were identified via the risk quotient approach to predict the associated toxicity for freshwater organisms in recipient surface waters. Currently, two options for HF wastewater treatment are preferred, i.e., disposal by deep well injection or on-site re-use as a fracturing fluid. Supplementary treatment will be enforced by increasingly rigorous regulations. Partial treatment and reuse remain the preferred method for managing HF wastewater where feasible. Otherwise, advanced technologies such as membrane separation/distillation, forward osmosis, mechanical vapor compression, electrocoagulation, advanced oxidation, and adsorption-biological treatment will be required to satisfy the sustainable requirements for reuse or surface discharge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Shale oil and gas production via hydraulic fracturing poses risks to water quality and quantity. </LI> <LI> High risk level is related with the management of hydraulic fracturing wastewater. </LI> <LI> Wastewater quality data limitation is an obstacle for developing sustainable treatment strategies. </LI> <LI> Integration of multiple technologies is required for wastewater reuse or discharge. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A Simple Intermediate Approach of Sputter Deposition at Room Temperature for Improving the Stability of a-InGaZnO Thin Film Transistors

Chunlan Wang,Yebo Jin,Yuqing Li,Gangying Guo,Yongle Song,Hao Huang,Aolin Wang,Han He 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.4

Amorphous InGaZnO (a-InGaZnO) thin film transistors (TFTs) with stability and low-temperature deposition are importantchallenges for their application in flexible electronics. Herein, a-InGaZnO films were successfully obtained throughout thewhole process in the room-temperature sputtering system. An intermediate nitrogen treatment a-InGaZnO film link contributedto high performance a-InGaZnO TFTs. The current switching ratio of the optimal nitrogen treatment transistor is closeto 107,the field-effect mobility (μFE) is 11.7 cm2/Vs and threshold voltage (VTH) is − 0.12 V, respectively. And the 4-daythreshold voltage offset (ΔVTH) is reduced from 12.98 to 4.92 V. The improved electrical properties may be attributed to thereduction of defect concentration and average interfacial trap density due to nitrogen occupation of oxygen vacancies (VO).

An effective method for directly extracting lithium from a-spodumene by activated roasting and sulfuric acid leaching

Yuqing Zhang,Baozhong Ma,Yingwei Lv,Chengyan Wang,Yongqiang Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-

The global trend toward electrification has encouraged lithium’s market position to grow prominently. Spodumene is the focus of lithium extraction owing to its abundant lithium resources. In this study, anovel lithium extraction method was proposed for a-spodumene by combining activated roasting andsulfuric acid leaching. First, the thermodynamics of the roasting process demonstrated that aspodumenewas converted into b-spodumene, which reacted with CaO to produce acid-solubleLiAlSiO4 and CaSiO3 concurrently. The addition of CaO reduced the melting temperature, which promotedthe structural transformation of b-spodumene and further acid leaching. Then, the influences of variousfactors on lithium extraction were investigated by a single-factor test. A lithium leaching yield of 96.18%was obtained under optimum conditions: 20% CaO, roasting temperature of 1200 C, holding time of1.5 h, H2SO4 concentration of 120 g/L, liquid–solid ratio of 7:1 mL/g, leaching temperature of 80 Cand leaching time of 1.5 h. Finally, Li entered into leach liquor by the action of sulfuric acid, and the maincomponents of the leach residue were silicate and calcium sulfate. Compared to the conventional acidapproach, this method has a higher lithium recovery and lower energy and acid consumption (decreaseby approximately 0.42 kg/ kg).

Cobalt-Porphyrin Modified Three-Dimensional Graphene Hydrogel Electrode for High Performance Asymmetric Supercapacitors

Yuqing Song,Hongfei Wang,Lifeng Yan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.5

Three-dimensional (3D) graphene-based materials have attracted much attention in the field of supercapacitors for their large surface areas and fast electronic conductivity capability. Faradaic pseudo-capacitance materials inside the architecture can enlarge the electrochemical performance of the electrode. Additionally, metal porphyrins are negative electrode active materials for supercapacitors as they have potential high pseudo-capacitance, conductivity and N-doping. The design and preparation of the 3D cobalt-porphyrin modified graphene hydrogels (3D CoP/GHs) is an interesting topic. Here, we have fabricated the 3D CoP/GH by a two-step method. The composite electrode reaches a specific capacitance of 335 F g -1, twice that of pure GHs. At the same time, resistance of the electrode material decreases and the ion transfer is accelerated due to the addition of cobalt-porphyrin. After 10 000 cycles, the 3D CoP/GH maintains its stable specific capacitance retention of 94.11% indicating its excellent cycle life. The cycle life is much better than that of a hydrogel that has not been doped (81.63%) according to our previous work. Then we fabricated an asymmetrical supercapacitor which uses both the 3D CoP/GH and GH as the two electrodes (3D CoP/GHjjGH), and reaches an outstanding energy density of 30.40 Wh kg -1 at a current density of 1 A g -1 while the power density is 749.5 W kg -1.

Integration of Information Technology and Traditional Taekwondo Curriculum

Yuqing Guo,Daqing Wang,Xiuli Cheng 보안공학연구지원센터(IJUNESST) 2014 International Journal of u- and e- Service, Scienc Vol.7 No.3

The Long Noncoding RNA NEAT1 Targets miR-34a-5p and Drives Nasopharyngeal Carcinoma Progression via Wnt/β-Catenin Signaling

Yuqing Ji,Man Wang,Xueshen Li,Fusheng Cui 연세대학교의과대학 2019 Yonsei medical journal Vol.60 No.4

Purpose: Long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) has been deemed an oncogene in many humancancers. However, the underlying mechanism of NEAT1 in nasopharyngeal carcinoma (NPC) progression remains largelyunclear. Materials and Methods: Quantitative real-time PCR assay was performed to assess the expression of NEAT1 and miR-34a-5p inNPC tissues and cells. Western blot analysis was used to observe cell epithelial to mesenchymal transition (EMT) and the activationof Wnt/β-catenin signaling in 5-8F cells. MiRNA directly interacting with NEAT1 were verified by dual-luciferase reporter assayand RNA immunoprecipitation. Cell proliferation ability was determined by CCK-8 assay, and cell migration and invasion capacitieswere assessed by transwell assays. An animal model was used to investigate the regulatory effect of NEAT1 on tumorgrowth in vivo. Results: Our data revealed that NEAT1 is upregulated, while miR-34a-5p is downregulated in NPC tissues and cell lines. NEAT1knockdown repressed tumor growth in vitro and in vivo. Additionally, we discovered that NEAT1 directly binds to miR-34a-5pand suppresses miR-34a-5p expression. Moreover, NEAT1 knockdown exerted suppression effects on cell proliferation, migration,invasion, and EMT by miR-34a-5p. NEAT1 knockdown blocked Wnt/β-catenin signaling via miR-34a-5p. Conclusion: Our study demonstrated that NEAT1 targets miR-34a-5p at least partly to drive NPC progression by regulating Wnt/β-catenin signaling, suggesting a potential therapeutic target for NPC.

Research on characterization method and influencing factors of sedimentation stability of magnetorheological fluid

Yuqing Li,YiPing Luo,Ying Wang,Jiao Luo,Yameng Chen 한국유변학회 2021 Korea-Australia rheology journal Vol.33 No.4

The sedimentation stability of Magnetorheological fluid (MRF) is one of the research hotspots in the academic field of magnetorheological science. Excellent sedimentation stability is of great significance for the preservation and application of MRF. Given many traditional methods of characterization of sedimentation stability, this paper proposes a new method to characterize the sedimentation stability of MRF based on the change of shear yield stress during the sedimentation process of MRF. Then, the key components of the selfmade MRF shear yield stress test device were introduced in detail, and three different surfactants containing dodecyl benzoate, polyethylene glycol and oleic acid were prepared. And then used the device to test their effects on the sedimentation stability of MRF. The results showed that oleic acid has the best effect on improving the sedimentation stability. Finally, the change law of shear yield stress of MRF in the next 90 days was predicted successfully by fitting experimental data based on the least square method. By comparing the test value and fitting value of 60-75 days, the error of the best fitting result were within 3%, this showed the reliability of the predicted results.