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Search Results: 1 - 10 of 28203 matches for " Chenkai Zhu "
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Hybrid Composites of Phosphate Glass Fibre/Nano-Hydroxyapatite/Polylactide: Effects of Nano-Hydroxyapatite on Mechanical Properties and Degradation Behaviour  [PDF]
Lizhe He, Chenkai Zhu, Jiahao Wu, Xiaoling Liu
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.611002
Abstract: Hydroxyapatite/polylactide (HA/PLA) composites have been intensively investigated for their potential as biodegradable fixation devices to heal bone fractures. However, most of these composites failed to achieve a bone-mimicking level of mechanical properties, which is an essential demand of the targeted application. In this study, the nano-hydroxyapatite/polylactide composites were used as the matrix and continuous phosphate glass fibres (PGF) served as the major reinforcement to obtain the nano-HA/PGF/PLA hybrid composites. While the PGF volume fraction remained constant (25%), the nano-HA content (in weight) varied from 0% to 20%. As nano-HA loading increased, the flexural modulus of the composites increased from 8.70 ± 0.35 GPa to 14.97 ± 1.30 GPa, and the flexural strengths were enhanced from 236.31 ± 10.83 MPa to 310.55 ± 22.88 MPa. However, it is found that the degradation rates are higher with more nano-HA loaded. Enhanced water absorption ability, as well as increased voids in the composites is possible reasons for the accelerated degradation of composites with higher nano-HA loading. The hybrid composites possess mechanical properties that are superior to most of the HA/PLA composites in previous research while maintaining the biodegradability. With a proper loading of nano-HA in composites of 10 weight percent, the composites are also found with improved mechanical properties without catastrophic degradation. The composites developed in this study have great potential as biodegradable bone fixation device with enhanced load-bearing ability as confirmed and superior bioactivity as anticipated.
The Effects of Fe2O3 and B2O3 on the Glass Structural, Thermal, in Vitro Degradation Properties of Phosphate Based Glasses  [PDF]
Chenkai Zhu, Jinsong Liu, Songling Huang, Lizhe He, Xiaoye Cong, Chao Tan, Chris Rudd, Xiaoling Liu
New Journal of Glass and Ceramics (NJGC) , 2017, DOI: 10.4236/njgc.2017.74009
Abstract: Currently, phosphate based glasses have been potential future biomaterial for medical application due to excellent cytocompatibility and fully bioresorbability. In this study, phosphate based glass system with composition of 48P2O5-12B2O3-(25-X)MgO-14CaO-1Na2O-(X)Fe2O3 (X = 6, 8, 10) and
45P2O5-(Y)B2O3-(32-Y)MgO-14CaO-1Na2O-8Fe2O3 (Y = 12, 15, 20), was prepared via a melting quenching process. The effect of replacing MgO with Fe
Sandwich Structure Composite with Expandable Graphite Filled or Coated: Evaluation of Flame Retardancy and Mechanical Performances  [PDF]
Chenkai Zhu, Jingjing Li, Fanhao Ji, Xiaosu Yi, Chris Rudd, Xiaoling Liu
Open Journal of Safety Science and Technology (OJSST) , 2019, DOI: 10.4236/ojsst.2019.91002
Abstract: Sandwich composites are increasingly used in high-performance application due to their high specific stiffness, strength and thermal insulation. The sandwich composites were developed using honeycomb and carbon fibre reinforced composite face sheet in this study. Expandable graphite (EG) weighting 5 wt% and 10 wt% were filled in honeycomb or coated on face sheet to improve the fireproof performance. The vertical burning test, cone calorimetry test, thermal insulation analysis, scanning electron microscopy and mechanical test were taken into account. With the increase of EG in the sandwich composites, a significant improvement on flame retardancy with better thermal insulation, lower values of peak heat release rate and MAHRE were confirmed for sandwich composite with EG both coated and filled. In addition, the sandwich with EG coated on face sheet presented better fire resistivity and thermal insulation properties when compared to that with EG filled in honeycomb. However, more total smoke release was also observed for EG coated composites due to partial combustion of resin within sufficient heat and oxygen. Furthermore, no significant effect on the mechanical properties of composites was confirmed from both fireproof approaches.
Extension Study on Electricity Market of Power Plant Investment Environment  [PDF]
Yuting Wang, Kezhen Liu, Chenkai Mo
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B170

When the global electricity industry has reorganized the structure and introduced competitive market mechanism world widely, China is no exception. Since 2002, Electricity System Reform Program was enacted. The mode of the State Power Corporation was divided. It means China's electricity market steps into the mode of Wholesale Competition. The meaning of the evaluation of power plant investment decision is to provide references for the market members when they made the decisions through the comprehensive evaluation of internal performance of Power Plant and the external investment environment, therefore further optimizing the allocation of funds, avoiding the risks, pursuing maximize of the profits.

Inhibition of STAT3 Reduces Astrocytoma Cell Invasion and Constitutive Activation of STAT3 Predicts Poor Prognosis in Human Astrocytoma
Qinchuan Liang, Chenkai Ma, Yang Zhao, Guodong Gao, Jie Ma
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0084723
Abstract: Astrocytoma cells characteristically possess high invasion potentials. Recent studies have revealed that knockdown of signal transducers and activators of transcription 3 (STAT3) expression by RNAi induces apoptosis in astrocytoma cell. Nevertheless, the distinct roles of STAT3 in astrocytoma’s invasion and recurrence have not been elucidated. In this study, we silenced STAT3 using Small interfering RNAs in two human glioblastoma multiforme (GBM) cell lines (U251 and U87), and investigated the effect on GBM cell adhesion and invasion. Our results demonstrate that disruption of STAT3 inhibits GBM cell’s adhesion and invasion. Knockdown of STAT3 significantly increased E-cadherin but decreased N-cadherin, vascular endothelial growth factor, matrix metalloproteinase 2 and matrix metalloproteinase 9. Additionally, expression of pSTAT3Tyr705 correlates with astrocytoma WHO classification, Karnofsky performance status scale score, tumor recurrence and survival. Furthmore, pSTAT3Tyr705 is a significant prognostic factor in astrocytoma. In conclusion, STAT3 may affect astrocytoma invasion, expression of pSTAT3Tyr705 is a significant prognostic factor in tumor recurrence and overall survival in astrocytoma patients. Therefore, STAT3 may provide a potential target for molecular therapy in human astrocytoma, and pSTAT3Tyr705could be an important biomarker for astrocytoma prognosis.
Head Movements Evoked in Alert Rhesus Monkey by Vestibular Prosthesis Stimulation: Implications for Postural and Gaze Stabilization
Diana E. Mitchell, Chenkai Dai, Mehdi A. Rahman, Joong Ho Ahn, Charles C. Della Santina, Kathleen E. Cullen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078767
Abstract: The vestibular system detects motion of the head in space and in turn generates reflexes?that are vital for our daily activities. The eye movements produced by the vestibulo-ocular reflex (VOR) play an essential role in stabilizing the visual axis (gaze), while vestibulo-spinal reflexes ensure the maintenance of head and body posture. The neuronal pathways from the?vestibular periphery to the cervical spinal cord potentially serve a dual role, since they function to stabilize the head relative to inertial space and could thus contribute to gaze (eye-in-head + head-in-space) and posture stabilization. To date, however, the functional significance of vestibular-neck pathways in alert primates remains a matter of debate. Here we used a vestibular prosthesis to 1) quantify vestibularly-driven head movements in primates, and 2) assess whether these evoked head movements make a significant contribution to gaze as well as postural stabilization. We stimulated electrodes implanted in the horizontal semicircular canal of alert rhesus monkeys, and measured the head and eye movements evoked during a 100ms time period for which the contribution of longer latency voluntary inputs to the neck would be minimal. Our results show that prosthetic stimulation evoked significant head movements with latencies consistent with known vestibulo-spinal pathways. Furthermore, while the evoked head movements were substantially smaller than the coincidently evoked eye movements, they made a significant contribution to gaze stabilization, complementing the VOR to ensure that the appropriate gaze response is achieved. We speculate that analogous compensatory head movements will be evoked when implanted prosthetic devices are transitioned to human patients.
A Study on the Driving Factors of Tourism Destination Brand Equity Based on Internet Sharing Content: A Case Study of Shenzhen Happy Valley  [PDF]
Ju Zhu, Mingfang Zhu
Journal of Service Science and Management (JSSM) , 2018, DOI: 10.4236/jssm.2018.116039
Abstract: Thanks to increasing mature tourists, continuous innovation on science and technology, improved accessibility of attractions, the destination has to confront the growing competition tourism destinations leading to the importance of consumer based brand equity. The paper, taking the tourists’ evaluation and sharing contents of Shenzhen Happy Valley obtained on Mafengwo website as the text material, constructs a tourism destination brand equity driving factor model with “product”, “experience” and “marketing” as the core category based on the grounded theory Through the study, the driving factors of brand equity of destination are identified, and corresponding suggestions are provided for the management of destination brand equity.
Principle and Characteristic of Lorentz Force Propeller  [PDF]
Jing ZHU
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2009, DOI: 10.4236/jemaa.2009.14034
Abstract: This paper analyzes two methods that a magnetic field can be generated, and classifies them under two types: 1) Self-field: a magnetic field can be generated by electrically charged particles move, and its characteristic is that it can’t be independent of the electrically charged particles. 2) Radiation field: a magnetic field can be generated by electric field change, and its characteristic is that it independently exists. Lorentz Force Propeller (ab. LFP) utilize the characteristic that radiation magnetic field independently exists. The carrier of the moving electrically charged parti-cles and the device generating the changing electric field are fixed together to form a system. When the moving electrically charged particles under the action of the Lorentz force in the radiation magnetic field, the system achieves propulsion. Same as rocket engine, the LFP achieves propulsion in vacuum. LFP can generate propulsive force only by electric energy and no propellant is required. The main disadvantage of LFP is that the ratio of propulsive force to weight is small.
China’s Savings and Current Account Balance: A Demographic Transition Perspective  [PDF]
Chao Zhu
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.25089
Abstract: In this paper, we build an overlapping generation model to analyze how China’s family planning policy affects the demographic structure and the dependency ratios. We also employ the Cointegration Test and Granger Causality Test to examine the relationship between Chinese population dependency ratios and the national savings rate, as well as the relationship between relative productivity differences and the national current account balance. We find that the family planning policy can be sustainable with respect to these metrics. The current account balance reflects the transfer of savings over time and space. We posit that the demographic structure determines the savings transfer over time, while the relative productivity difference determines the savings transfer across the space. This transfer does not change the total welfare calculated on a national or generational basis. Consequently, focusing on improving the consumption rate to boost the economy without consideration of demographic structure transition warrants further serious discussion. Similarly, too much attention to short-term current account surplus or deficit is not productive.
Credit Rating in China’s Bond Market: Evidence from Short-Term Financing Bonds  [PDF]
Song Zhu
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.42015

In recent years, the Chinese government has highly emphasized the development of bond market, which plays an important role during the development of macro-economy and finance sector in China, especially on some crucial steps concerning national economy and the peoples livelihood, as well as reforms in banking industry and the financial innovations. However, the bond market is smaller compared with its counterparts abroad, and its structure is much simpler. To promote the development of bond market, credit rating is very important, which has been hotly discussed during and after the recent financial crisis. This paper discusses the credit rating of bond in China, particularly the short-term financing bonds (STFBs). Our results reveal that almost all credit ratings for STFBs are A-1, the highest rating, which cannot provide investors with effective information, thus being consistent with some critical voices. However, the credit ratings for issuing firms exhibit significant difference so that they are reliable benchmarks for bond investors, and credit ratings indeed reflect the risk of issuing firms in China. Our paper provides more information for foreign and domestic investors about the bond market and the credit rating in China, and gives answer to the question about efficiency of bond rating in China. We provide some evidence for the reliability of rating in China though it is still in its early stage.

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