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      • Supercapacitors with ultrahigh energy density based on mesoporous carbon nanofibers: Enhanced double-layer electrochemical properties

        Li, Zhen-Yu,Akhtar, M. Shaheer,Yang, O-Bong Elsevier 2015 Journal of alloys and compounds Vol.653 No.-

        <P><B>Abstract</B></P> <P>High performance electrochemical double-layer (EDL) supercapacitor was fabricated with highly efficient electro-active electrode based on mesoporous carbon nanofibers (MCFs) materials. The prepared MCFs from dextrose as carbon source exhibited the high surface to volume ratio, large pore volume and high mesoporous nature. The cyclic voltammetry, electrochemical impedance and galvanostatic charge–discharge measurements were carried out to investigate the capacitive and electrochemical behavior of fabricated EDL supercapacitor based on MCFs electrode. A reasonably high specific capacitance of 201 F/g at current density of 0.6 A/g was achieved by the fabricated EDL supercapacitor based on MCFs electrode. A relation of capacitive performance, specific surface area, accessible average pore size and current density was manifested to evaluate the impact of capacitance parameters. The fabricated EDL supercapacitor based on MCFs electrode attained the ultra high energy density of 54.7 W h/kg and reasonable power density of 0.842 kW/kg at the current density of 0.6 A/g. The fabricated EDL supercapacitor manifested an excellent stability by keeping about 88% of initial capacity after 1000 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient electro-active electrode prepared by mesoporous carbon nanofibers. </LI> <LI> High performance electrochemical double layer (EDL) supercapacitor was fabricated. </LI> <LI> EDL supercapacitor with MCFs electrode showed the high specific capacitance of 201 F/g. </LI> <LI> Ultra high energy density of 54.7 W h/kg and power density of 0.842 kW/kg attained. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • SCISCIESCOPUS

        Microstructure evolution and enhanced vacuum tribological performance of Ni-doped WS<sub>2</sub> composite coating

        Xu, Shu-Sheng,Weng, Li-Jun,Liu, Yu-Zhen,Kang, Kyeong-Hee,Kim, Chang-Lae,Kim, Dae-Eun Elsevier Sequoia 2017 Surface & coatings technology Vol.325 No.-

        <P><B>Abstract</B></P> <P>Ni-doped WS<SUB>2</SUB> composite coatings with various Ni contents were co-deposited using a radio frequency sputtering system on silicon wafer and AISI 440C stainless steel substrates. The microstructural characteristics of the WS<SUB>2</SUB>-Ni composite coatings and their tribological properties in vacuum were assessed. During introduction of Ni dopant in the WS<SUB>2</SUB>-Ni composite coating the sulfur/tungsten (S/W) ratio in the coating increased due to reduced preferential resputtering of sulfur atoms in the growing coating. The microstructure of the WS<SUB>2</SUB>-Ni composite coating varied from a fine columnar structure for Ni content equal to or less than 7.7at.% to a featureless structure as the Ni content increased further. The Ni dopant inhibited the growth of the coarse columnar WS<SUB>2</SUB> platelets which was accompanied by nanocrystallization and amorphization of the composite coating structure. WS<SUB>2</SUB>-Ni composite coatings with fine columnar structure exhibited relatively low hardness but showed a high tendency to form a lubricating transfer layer. It also demonstrated low brittleness and prolonged wear life in vacuum condition compared to coatings with dense featureless structure. The variation in tribological performance between the composite coatings resulted from the different wear mechanisms associated with their distinct microstructures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microstructure of WS<SUB>2</SUB> coating was modified by incorporating Ni as a dopant. </LI> <LI> The introduction of Ni increased the S/W ratio of the WS<SUB>2</SUB> composite coating. </LI> <LI> High Ni content in the WS<SUB>2</SUB> coating led to high brittleness and low wear resistance. </LI> <LI> WS<SUB>2</SUB>–5at.% Ni coating showed 5 times longer wear life than pure WS<SUB>2</SUB> film in vacuum. </LI> <LI> Superior tribological properties were attributed to transfer layer and high hardness. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • SCISCIESCOPUS

        Rotary ultrasonic machining of woven CFRP composite in a cryogenic environment

        Thirumalai Kumaran, S.,Ko, Tae Jo,Li, Changping,Yu, Zhen,Uthayakumar, M. ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.698 No.-

        <P><B>Abstract</B></P> <P>In the present study, rotary ultrasonic machining (RUM) was adopted to perform drilling of carbon fiber reinforced plastics (CFRP) in a cryogenic environment. An L27 orthogonal array was selected to conduct experiments by varying the spindle speed (denoted as N), feed rate (denoted as f), and ultrasonic power (denoted as P). The thrust force (denoted as Fz), exit burr area, and surface roughness (denoted as Ra) were measured to evaluate the machining performance. The influence of process parameters and the regression model were derived for each output quality response. Additionally, multi-objective optimization was performed using desirability analysis, and the predicted levels were used for confirmation. The results indicated that the feed rate (f) contributed more to the thrust force (Fz) by 45.85% and a maximum thrust force was recorded at 0.1 mm/rev. A decrease in spindle speed (N) was associated with an increase in feed rate (f) and ultrasonic power (P), and it resulted in minimum exit burr area. The influence of ultrasonic power (P) was highly significant in reducing burrs with a contribution of 52.45%. Conversely, the surface roughness (Ra) of the drill holes decreased at 3000 rpm, and this was attributed to the brittle fracture of the fibers at a lower temperature. Both N (30.88%) and f (30.83%) had an equal influence on producing a better surface finish in the drill holes. Furthermore, the predicted optimal settings were used to validate the results and were found to be within 95% confidence and prediction interval. Finally, the microscopic images of tool wear, burr formation, and drill hole surface morphology were analyzed and examined.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Prediction of regression model for RUM of CFRP in a cryogenic environment. </LI> <LI> Output responses such as thrust force, burr area and roughness are investigated. </LI> <LI> The adequacy of an ANOVA model is checked for each output response. </LI> <LI> Optimization is performed by desirability analysis and the results are validated. </LI> <LI> Tool wear, burr formation, and drill hole surface morphology are analyzed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

      • SCISCIESCOPUS
      • KCI등재

        Effect of Sub-Structure and Precipitation Behavior on Mechanical Properties of Al–xCu–Li Alloys

        Yu‑zhuo Li,Guang‑jun Zeng,Ding‑ding Lu,Zhenzhen Liu,San‑xi Deng,Peng‑cheng Ma,Yong‑lai Chen,Rui‑feng Zhang,Jin‑feng Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

        The tensile properties and microstructure of extruded and cold rolled 2A55 Al–Li alloys with different Cu content werestudied. After solution treatment, the strength of extruded sheets is slightly higher than that of cold rolled sheets due to strongdeformation texture and high density of substructure. However, the strength change order is different with the increase of Cucontent with T6-24 h. The extruded sample with higher Cu content have higher strength due to many dense T1precipitates. The δ′/θ′/δ′ composite precipitates and θ′ precipitates suppress the formation of T1precipitates, which cause cold rolled samplewith higher Cu content shows lower strength. Additionally, many fine T1precipitates nucleate at the sub-grain boundariesformed in the extrusion process, which have a significant effect on the mechanical property.

      • Colorectal Cancer Concealment Predicts a Poor Survival: A Retrospective Study

        Li, Xiao-Pan,Xie, Zhen-Yu,Fu, Yi-Fei,Yang, Chen,Hao, Li-Peng,Yang, Li-Ming,Zhang, Mei-Yu,Li, Xiao-Li,Feng, Li-Li,Yan, Bei,Sun, Qiao Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.7

        Objectives: Understanding the situation of cancer awareness which doctors give to patients might lead to prognostic prediction in cases of of colorectal cancer (CRC). Methods: Subsets of 10,779 CRC patients were used to screen the risk factors from the Cancer Registry in Pudong New Area in cancer awareness, age, TNM stage, and gender. Survival of the patients was calculated by the Kaplan-Meier method and assessed by Cox regression analysis. The views of cancer awareness in doctors and patients were surveyed by telephone or household. Results: After a median observation time of 1,616 days (ranging from 0 to 4,083 days) of 10,779 available patients, 2,596 of the 4,561 patients with cancer awareness survived, whereas 2,258 of the 5,469 patients without cancer awareness and 406 of the 749 patients without information on cancer awareness died of the disease. All-cause and cancer-specific survival were poorer for the patients without cancer awareness than those with (P < 0.001 for each, log-rank test). Cox multivariate regression analysis showed that cancer concealment cases had significantly lower cancer-specific survival (hazard ratio (HR) = 1.299; 95 % confidence interval (CI): 1.200-1.407)and all-cause survival (HR = 1.324; 95 % CI: 1.227-1.428). Furthermore, attitudes of cancer awareness between doctors and patients were significantly different (P < 0.001). Conclusion: Cancer concealment, not only late-stage tumor and age, is associated with a poor survival of CRC patients.

      • Tumor-Derived Transforming Growth Factor-β is Critical for Tumor Progression and Evasion from Immune Surveillance

        Li, Zheng,Zhang, Li-Juan,Zhang, Hong-Ru,Tian, Gao-Fei,Tian, Jun,Mao, Xiao-Li,Jia, Zheng-Hu,Meng, Zi-Yu,Zhao, Li-Qing,Yin, Zhi-Nan,Wu, Zhen-Zhou Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

        Tumors have evolved numerous mechanisms by which they can escape from immune surveillance. One of these is to produce immunosuppressive cytokines. Transforming growth factor-${\beta}$(TGF-${\beta}$) is a pleiotropic cytokine with a crucial function in mediating immune suppression, especially in the tumor microenvironment. TGF-${\beta}$ produced by T cells has been demonstrated as an important factor for suppressing antitumor immune responses, but the role of tumor-derived TGF-${\beta}$ in this process is poorly understood. In this study, we demonstrated that knockdown of tumor-derived TGF-${\beta}$ using shRNA resulted in dramatically reduced tumor size, slowing tumor formation, prolonging survival rate of tumor-bearing mice and inhibiting metastasis. We revealed possible underlying mechanisms as reducing the number of myeloid-derived suppressor cells (MDSC) and $CD4^+Foxp3^+$ Treg cells, and consequently enhanced IFN-${\gamma}$ production by CTLs. Knockdown of tumor-derived TGF-${\beta}$ also significantly reduced the conversion of na$\ddot{i}$ve $CD4^+$ T cells into Treg cells in vitro. Finally, we found that knockdown of TGF-${\beta}$ suppressed cell migration, but did not change the proliferation and apoptosis of tumor cells in vitro. In summary, our study provided evidence that tumor-derived TGF-${\beta}$ is a critical factor for tumor progression and evasion of immune surveillance, and blocking tumor-derived TGF-${\beta}$ may serve as a potential therapeutic approach for cancer.

      • KCI등재

        중국 100대 기업의 심볼마크 선호색에 관한 상징적 의미 분석

        이진우 ( Zhen Yu Li ) 한국기초조형학회 2015 기초조형학연구 Vol.16 No.2

        1973년, 개혁개방 이후 고속 성장에 힘입어 중국 경제는 나날이 발전을 거듭하며 오늘날 세계 최대의 잠재 시장으로 떠오르며 새로운 발전 단계에 이르렀다. 따라서 중국의 기업들은 세계 각국의 주목을 받고 있으며 더불어 심벌마크 디자인과 그 색상은 글로벌이라는 차원에서 그 중요성도 더욱 커지고 있다. 본 연구는 포춘(Fortune)이 선정한 2014년500대 기업 가운데 중국기업 100개를 조사대상으로 선정, 기업의 심볼마크 색상사용 현황 및 색상의 상징적 의미에 대해 분석하였다. 그 결과 중국기업이 가장 선호하는 색상은 파란색이며, 그 뒤를 이어 빨간색, 초록색, 노란색 순으로 조사되었다. 그 중 파란색은 주로 창의성과 혁신, 건강, 젊음과 바다를 상징하였다. 빨간색은 주로 어려움을 두려워하지 않고, 고군분투의 정신을 상징하였다. 한편으로는 불꽃을 상징해 뜨거움과 열정을 나타내기도 한다. 또한 태양을 상징하기도 해서 나날이 번창한다는 뜻도 내포하고 있다. 붉은 산단(山丹)도 상징해 산단(山丹)이 갈수록 화려하고 부흥하라는 의미도 갖고 있다. 초록색은 건강, 생명력, 청결을 상징해 환경 보호와 에너지절약의 뜻을 내포하고 있다. 노란색은 주로 황금색과 중국 국기의 노란색, 두 가지 색상을 가리키며 대지(大地)와 황하(黃河)를 상징한다. Nowadays, as Chinese market is paid attention to by enterprises around the world, the use of Chinese corporate logo color has received more attention. In this paper, we take the 100 Chinese enterprises on the latest 2014 Fortune Top 500 List as the respondents, to analyze the use of corporate logo color. In the survey, we found that blue is the most preferred color, followed by red, green and yellow. Blue mainly symbolizes innovation,renovation,health,youth, the sea and so on. Red mainly symbolizes being not afraid of difficulties and the courage of fighting. It symbolizes fire, which is hot and passionate; it symbolizes sun, which is flourishing and thriving; it also symbolizes the red Morningstar lily flower, showing that it is brighter and better year by year. Green symbolizes health, vitality, also a symbol of tidiness, meaning environmental protection and energy saving. Yellow mainly symbolizes gold and the way our national flag yellows, a symbol of the ground and the Yellow River.

      • KCI등재

        Novel Environmentally Friendly Manufacturing Method for Micro-Textured Cutting Tools

        Changping Li,Xinyi Qiu,Zhen Yu,Shujian Li,Pengnan Li,Qiulin Niu,Rendi Kurniawan,고태조 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.1

        Surface texturing on cutting tools has a great influence on reducing the friction force between tool and chip interfaces. In this study, a grinding method was developed to fabricate micro-groove textures on cutting tools using a special diamond grinding wheel on the tool rake face. A comparative experiment was done using a laser and other grinding method to fabricate micro-grooves. The developed grinding method does not produce harmful gases, it is environmentally friendly, and it fabricates groove textures with high efficiency and quality. Various micro-grooves with depths of 30–90 μm, groove pitches of 0.5–1 mm, and groove angles of 30–60 o were made on the rake faces of non-coated end-mill tools using the developed grinding method. Milling experiments on aluminum alloy (Al6061-T6) and tool steel (SKD11) with non-water-soluble coolant were carried out using the textured tools, and the cutting force and tool wear were investigated. In most cases, the cutting force produced by the micro-grooved tools is significantly reduced. In addition, the wear resistance of the micro-groove cutting tool is better than that of a conventional cutting tool, and there is no chipping.

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