Mechanism underlying the effect of conventional drying on the grinding characteristics of Ximeng lignite

Yumeng Yang,Jianzhong Liu,Xiang He,Zhihua Wang,Junhu Zhou,Kefa Cen 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.4

Same amounts of moisture were removed from Ximeng lignite (XL) with different particle size ranges pretreated at different drying temperatures. The effect of conventional drying on the grindability of the XLs was investigated. Increasing the drying temperature improved the grindability of all the samples. The results of scanning electron microscopy and mercury intrusion porosimetry revealed that the dominant mechanism enhancing the grindability of XL with high moisture was the pore structure destruction induced by the steam jet flow generated with the removal of moisture. Especially, the development of large fractures had a strong connection with the change in the grindability. According to the pore size distribution, the internal structure of the 2.5-4.0mm coal samples did not develop well under high drying temperature because of the exceedingly short heating time. Therefore, coal particle size, drying temperature, and heating time must be coordinated well to achieve the enhanced drying effect. The grindability of XL had a negative linear correlation with the pore volume fractal dimension, revealing the possibility of fractal dimension for the analysis of lignite grindability.

Post-Process Modification of CeOx/C-Supported PtCu Thin Film Catalyst and Its Catalytic Activity for Hydrogen Evolution Reaction

Yumeng Zhao,Bin Yang,Xinyu Hao,Zhijing Zhao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.6

CeOx/C supported PtCu thin film catalysts were prepared by ion beam sputtering (IBS) and subsequently annealed at 400℃ under vacuum environment and electrochemically dealloyed. Scanning transmission electronic microscope (STEM) and atomic force microscope (AFM) characterizations show that the surface of post-processed catalyst presents nanoporous structure and has a high root mean square roughness ( RMS=13.9 nm). Electrochemical measurements indicate that the post-processed PtCu – CeOx/C catalyst shows higher catalytic activity towards hydrogen evolution reaction than pure Pt/C. While inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis displays that the platinum (Pt) loading of the post-processed PtCu – CeOx/C is 0.1192 mg/cm2, decreasing by 20% compare to pure Pt/C (0.1490 mg/cm2). X-ray photoelectron spectroscopy (XPS) analysis confirms that the surface of post-processed PtCu – CeOx/C enrich Pt and analyzes the chemical valence of Pt element using depth profiling technology. It can be inferred that the enhancement in catalytic property is attributed to the combined action between geometric structure effect and electronic modification effect of Pt atoms from CeOx support.

Fabrication of High-Aspect-Ratio Microwire Electrodes Using a Vertical Liquid Membrane Electrochemical Etching Method

Yumeng Sang,Xiujuan Wu,Yongbin Zeng,Tao Yang 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.7

A vertical liquid membrane electrochemical etching method is proposed for the fabrication of high-aspect-ratio microwire electrodes. The potential and current density distributions are simulated using COMSOL software. The simulation results show that the unique potential distribution generated by the proposed method, combined with reciprocating linear motion of the wire electrode, can be used to fabricate microwire electrodes with large aspect ratio. These simulation results are verified experimentally. Different concentrations of electrolyte result in different reaction rates and thus different distributions of the diffusion layer and different bubble flows, resulting in different morphologies of the prepared wire electrodes. The effect of electrolyte concentrations is studied experimentally. At low electrolyte concentrations, the products of electrolysis are removed from the processing area under the action of gravity, and uniform electrodes with high aspect ratio can be prepared. At high electrolyte concentrations, intense bubble production destroys the diffusion layer around the electrode and leads to a dynamic equilibrium state, allowing the preparation of uniform wire electrodes in a rough machining process. The proposed method can prepare wire electrodes with different initial diameters. In this paper, uniform wire electrodes of length 1900 μm, diameter 7 μm, and aspect ratio 270 are fabricated by the proposed method from a tungsten wire of initial diameter 50 μm.

The combination of curcumin and 5-fluorouracil in cancer therapy

Yumeng Wei,Panjing Yang,Shousong Cao,Ling Zhao 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.1

5-Fluorouracil (5-FU) alone or in combinationwith other therapeutic drugs has been widely used forclinical treatment of various cancers. However, 5-FU-basedchemotherapy has limited anticancer efficacy in clinic dueto multidrug resistance and dose-limiting cytotoxicity. Some molecules and genes in cancer cells, such as nuclearfactor kappa B, insulin-like growth factor-1 receptor, epidermalgrowth factor receptor, cyclooxygenase-2, signaltransducer and activator of transcription 3, phosphatase andtensin homolog deleted on chromosome ten and Bcl-2 etc. are related to the chemoresistance and sensitivity of cancercells to 5-FU. The activation of these molecules and genesexpressions in cancer cells will be increased or decreasedwith long-term exposure of 5-FU. Curcumin has beenfound to be able to negatively regulate these processes. Inorder to overcome the problems of 5-FU, curcumin hasbeen used to combine with 5-FU in cancer therapy.

Field Effect Transistors: Direct-Write Complementary Graphene Field Effect Transistors and Junctions via Near-Field Electrospinning (Small 10/2014)

Chang, Jiyoung,Liu, Yumeng,Heo, Kwang,Lee, Byung Yang,Lee, Seung-Wuk,Lin, Liwei Wiley (John WileySons) 2014 Small Vol.10 No.10

A Comparative Analysis of Chinese and Korean Tourism Legislation

Jianhong Wang,Xinmiao Yang,Yumeng Li 아시아사회과학학회 2023 Jornal of Asia Social Science Vol.10 No.3

In the face of today's thriving global tourism sector, China and South Korea, as two Asian tourism powerhouses, have each adopted unique laws, rules, and policies to manage their thriving tourism industries. Although both countries have achieved impressive accomplishments in tourism development, their tourism management legislation differs, which may result in differing management outcomes. This paper investigates the similarities and differences in tourism management legislation in China and South Korea, and provides a comparative analysis across a variety of dimensions, including legislative background, laws and regulations, regulatory bodies, and the protection of tourists' rights and interests. This paper uses a comparative research methodology to provide valuable insights for tourism policymakers, practitioners, and scholars to help them better understand the characteristics of tourism management in the two countries, to promote the improvement of tourism management legislation in China and South Korea, to facilitate the sustainable development of the tourism industry, to improve service quality, and to protect the rights and interests of tour operators.

Reactive Procedure for Robust Project Scheduling under the Activity Disruptions

Lei Li,Wanlin Liu,Yumeng Chen,Shun Yang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

The baseline schedule may become infeasible when disruptions happen during the execution of project. This will lead to project delays and financial losses. In this paper, we developed a robust reactive optimization model. Our objective is to maximize the robustness of reactive schedule. Moreover, a robust reactive procedure is proposed for baseline schedule under a series of disruptions caused by activity duration. To test the proposed approach, sets of J60 and J90 instances from the Project Scheduling Library (PSPLIB) were used. Meanwhile, we tested the reactive project scheduling with the aim of minimizing makespan and compared the maximal robustness reactive schedule and the minimal makespan reactive schedule. We developed a reactive procedure involving genetic algorithm for reactive scheduling due to its non-deterministic polynomial hard (NP-hard). The results indicated that robust reactive scheduling has the advantage in maintaining the schedule’s ability of tolerating variabilities and reducing the impact of activity disruptions on the makespan. The research results can help project managers develop a robust schedule which can tolerate variabilities in a random environment.