Fabrication of Water-Soluble CuInS2 Quantum Dots by Hot-injection Method and Phase Transfer Strategy

Chong Deng,Bowen Fu,Yanlai Wang,Lin Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.10

Here we report an optimized hot-injection method and a phase transfer strategy for the synthesis of water-soluble CuInS2 QDs with desired properties. The structure and morphology studies demonstrate that the resulting QDs are CuInS2 tetragonal phase with well-defined facets. It is also found that the crystal size gradually increases with the increase of reaction temperature, while the surface of QDs with pre- and post-phase transfer is functionalized with hydrophobic and hydrophilic ligands, respectively. Spectroscopy measurements reveal the size-dependent optical properties of CuInS2 QDs, demonstrating the quantum confinement effect in this system.

Performance Improvement of Delay-Tolerant Networks with Mobility Control under Group Mobility

( Ling Fu Xie ),( Peter Han Joo Chong ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.6

This paper considers mobility control to improve packet delivery in delay-tolerant networks (DTNs) under group mobility. Based on the group structure in group mobility, we propose two mobility control techniques; group formation enforcement and group purposeful movement. Both techniques can be used to increase the contact opportunities between groups by extending the group`s reachability. In addition, they can be easily integrated into some existing DTN routing schemes under group mobility to effectively expedite the packet delivery. This paper is divided into 2 parts. First, we study how our proposed mobility control schemes reduce the packet delivery delay in DTNs by integrating them into one simple routing scheme called group-epidemic routing (G-ER). For each scheme, we analytically derive the cumulative density function of the packet delivery delay to show how it can effectively reduce the packet delivery delay. Then, based on our second proposed technique, the group purposeful movement, we design a new DTN routing scheme, called purposeful movement assisted routing (PMAR), to further reduce the packet delay. Extensive simulations in NS2 have been conducted to show the significant improvement of PMAR over G-ER under different practical network conditions.

Molecular-resolution micro-resonant biosensor with adjustable natural frequency

Xiaorui Fu,Ming Zhang,Dezhi Hou,Chong Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

Modern sensors are becoming increasingly small in size while their sensitivity requirements remain relatively strict, to the point that the processing technology and test technology are highly difficult and costly. This paper proposes a micro-resonant biosensor with adjustable natural frequency. A positive feedback signal with a phase difference of 180 degrees is used to reduce the equivalent mass of the resonator, yielding an ultrahigh resonant frequency. The biosensor is formed by a coating bovine blood solution on the surface of the resonator of a cantilever sensor. The instantaneous frequency equation of the biosensor is established using a coupling dynamic calculation. The changes in instantaneous frequency during hemoglobin oxygen absorption and deoxygenation, are then measured. The proposed millimeter micro-resonant biosensor system measures the molecular weight of a single oxygen molecule quality at 5.7619×10 -23 g, only deviating by 8.306 % from the theoretical value. Finally, the potential of the micron scale sensor is deeply taped.

Dihydroartemisinine Enhances Dictamnine-induced Apoptosis via a Caspase Dependent Pathway in Human Lung Adenocarcinoma A549 Cells

An, Fu-Fei,Liu, Yuan-Chong,Zhang, Wei-Wei,Liang, Lei Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.10

Dictamnine (Dic) has the ability to exert cytotoxicity in human cervix, colon, and oral carcinoma cells and dihydroartemisinin (DHA) also has potent anticancer activity on various tumour cell lines. This report explores the molecular mechanisms by which Dic treatment and combination treatment with DHA and Dic cause apoptosis in human lung adenocarcinoma A549 cells. Dic treatment induced concentration- and time-dependent cell death. FCM analysis showed that Dic induced S phase cell cycle arrest at low concentration and cell apoptosis at high concentration in which loss of mitochondrial membrane potential (${\Delta}{\Psi}m$) was not involved. In addition, inhibition of caspase-3 using the specific inhibitor, z-DQMD-fmk, did not attenuate Dic-induced apoptosis, implying that Dic-induced caspase-3-independent apoptosis. Combination treatment with DHA and Dic dramatically increased the apoptotic cell death compared to Dic alone. Interestingly, pretreatment with z-DQMD-fmk significantly attenuated DHA and Dic co-induced apoptosis, implying that caspase-3 plays an important role in Dic and DHA co-induced cell apoptosis. Collectively, we found that Dic induced S phase cell cycle arrest at low concentration and cell apoptosis at high concentration in which mitochondria and caspase were not involved and DHA enhanced Dic induced A549 cell apoptosis via a caspase-dependent pathway.

Nonlinear primary resonance and bifurcation analyses of a micro-resonant pressure sensor

Xiaorui Fu,Chong Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

The micro-resonant pressure sensor outputs frequency signals for which distortion does not take place over long-distance transmission. As the dimensions of the sensor decrease, the nonlinear coupling effects caused by the van der Waals force, electrostatic force, and air damping force should be considered. Here, based on the nonlinear dynamic equation, the amplitude-frequency characteristics near resonance and the equation on the displacement response far away from resonance are obtained. Using these equations, changes in the sensor’s amplitude-frequency characteristics and the vibration amplitude far away from resonance, along with the system parameters, are investigated. The variations of the chaotic vibration characteristics of the sensor with the thickness of the resonator are studied by the numerical method. The results show that the relevant parameters of the resonator have a great influence on the primary resonance and bifurcation of the sensor. The sensor changes from periodic vibration to chaotic vibration through period-doubling bifurcation in a certain range of parameters. These results can be used to determine the measurements of the resonators to ensure sensor performance.

Adaptive Dynamic Neural-Q System for traffic signal control

BI FU LI,KIL TO CHONG 제어로봇시스템학회 2009 제어로봇시스템학회 합동학술대회 논문집 Vol.2009 No.12

Output characteristics and experiments of a novel low frequency rotary piezoelectric motor

Kang Liang,Chong Li,Yujian Tong,Jiwen Fang,Wei Zhong,Xiaorui Fu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

In order to improve the output performance of a piezoelectric motor under low driving frequency, a novel rotary piezoelectric motor driven by two piezoelectric actuators is proposed that is actuated based on harmonic and friction driving mechanism. The motor uses two piezoelectric actuators to drive two amplifying mechanisms with π/2 phase difference to produce harmonic motion, and then drives the rotor to rotate through friction force. Based on the driving principle, the electromechanical coupling equations of the motor are established. And a test platform is built to test the output characteristics of the motor. The results show that fluctuation of harmonic force and output torque occurs when the motor operates at different positions. Under the driving voltage and frequency of 150 V and 5 Hz, the actual average output torque of the prototype is 3.08 Nmm. Moreover, fluctuation of harmonic force and output torque occurs when the motor operates at different positions.

Magnetic-Field-Model and Circuit-Model Based Analysis of Three-Phase Magnetically Coupled Resonant Wireless Power Transfer Systems with Cylinder-Shaped Coils

Chen, Xuling,Fu, Xiewei,Jiang, Chong,Pei, Cunhui,Liu, Fuxin The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

Development of a Dynamic Algorithm for Traffic Signal Control

Li Bi Fu,Kil To Chong 대한전자공학회 2010 대한전자공학회 학술대회 Vol.2010 No.6

The Effects of Environmental Toxins on Allergic Inflammation

San-Nan Yang,Chong-Chao Hsieh,Hsuan-Fu Kuo,Min-Sheng Lee,Ming-Yii Huang,Chang-Hung Kuo,Chih-Hsing Hung 대한천식알레르기학회 2014 Allergy, Asthma & Immunology Research Vol.6 No.6

The prevalence of asthma and allergic disease has increased worldwide over the last few decades. Many common environmental factors are associated with this increase. Several theories have been proposed to account for this trend, especially those concerning the impact of environmental toxicants. The development of the immune system, particularly in the prenatal period, has far-reaching consequences for health during early childhood, and throughout adult life. One underlying mechanism for the increased levels of allergic responses, secondary to exposure, appears to be an imbalance in the T-helper function caused by exposure to the toxicants. Exposure to environmental endocrine-disrupting chemicals can result in dramatic changes in cytokine production, the activity of the immune system, the overall Th1 and Th2 balance, and in mediators of type 1 hypersensitivity mediators, such as IgE. Passive exposure to tobacco smoke is a common risk factor for wheezing and asthma in children. People living in urban areas and close to roads with a high volume of traffic, and high levels of diesel exhaust fumes, have the highest exposure to environmental compounds, and these people are strongly linked with type 1 hypersensitivity disorders and enhanced Th2 responses. These data are consistent with epidemiological research that has consistently detected increased incidences of allergies and asthma in people living in these locations. During recent decades more than 100,000 new chemicals have been used in common consumer products and are released into the everyday environment. Therefore, in this review, we discuss the environmental effects on allergies of indoor and outside exposure.