One-Pot Electrodeposition of NiS Nanoparticles as an Efficient Electrode for Nonenzymatic H2O2 and Glucose Sensors

Zhiheng Huang,Chunchuan Gu,Jiajun Wen,Langlang Zhu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

In this paper, a new and one-pot electrodeposition method was expanded for the preparation of NiS nanoparticles-based electrochemical biosensor using metal-ion complexes as a precursor. Thioacetamide was used to control the production rate of NiS nanoparticles for the first time. The proposed electrochemical sensor was characterized by energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscope (FESEM), cyclic voltammograms (CV), and electrochemical impedance spectra (EIS). Experiment parameters were optimized. Under the optimized condition, the prepared NiS-based biosensor exhibited excellent electrocatalytic oxidation of H2O2 and glucose due to their small size. It provided fast and sensitive strategy for detecting H2O2 and glucose in the range of 1–5000 and 1–1000 μM. The detection limit of 0.257 and 0.3 μM was obtained for H2O2 and glucose. The mechanisms were also analyzed. The proposed biosensor exhibited excellent anti-interference and repeatability. Furthermore, it was applied in the actual sample analysis, such as human blood serum.

Enhanced friction model for high-speed right-angle gear dynamics

Zhiheng Feng,Shilong Wang,Teik C. Lim,Tao Peng 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.11

The modeling of elastohydrodynamic lubrication friction and the analysis of its dynamic effect on right-angle gears, such as hypoid and spiral bevel types are performed in the present study. Unlike the classically applied empirical constant coefficient of friction at the contacting tooth surfaces, the enhanced physics-based gear mesh friction model is both spatial and time-varying. The underlying formulation assumes mixed elastohydrodynamic lubrication (EHL) condition in which the division and load distribution between the full film and asperity contact zones are determined by the film thickness ratio and load sharing coefficient. In the proposed time-varying friction model, the calculation of friction coefficient is performed at each contact grid inside the instantaneous contact area that is being subjected to mineral oil lubrication. The effective friction coefficient and directional parameters synthesized from the net frictional and normal contact forces are then incorporated into a nonlinear time-varying right-angle gear dynamic model. Using this model, the effect of friction on the gear dynamic response due to the transmission error and mesh excitations is analyzed. Also, parametric studies are performed by varying torque, surface roughness and lubrication properties to understand the salient role of tooth sliding friction in gear dynamics. The simulation results are included. But experimental verification is needed.

Controller Design for MIMO System with Time Delay Using Closed-loop Gain Shaping Algorithm

Zhiheng Zhang,Xianku Zhang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.6

In this paper, a general scheme is proposed for Multi Input Multi Output (MIMO) systems with time delays by using closed-loop gain shaping algorithm (CGSA). The controller is designed based on the minimum phase(MP) part of these processes. For every closed loop, there is the unique variable parameter, the performance and robustness can be tuned quantitatively to satisfy the practical requirements of project. Finally, three examples in published literatures are performed to illustrate the effectiveness of proposed method. Compared with the relative references, the control performances of proposed method are superior to those of existed research, and the control scheme is with advantages of concision and efficiency.

Optimization of fish oil extraction from Lophius litulon liver and fatty acid composition analysis

Zhiheng Hu,Yaoxian Chin,Jialin Liu,Jiaying Zhou,Gaoshang Li,Lingping Hu,Yaqin Hu 한국수산과학회 2022 Fisheries and Aquatic Sciences Vol.25 No.2

The Lophius litulon liver was used as raw material for the extraction of fish oil via various extraction methods. The extraction rate by water extraction, potassium hydroxide (KOH) hydrolysis and protease hydrolysis were compared and the results revealed the protease hydrolysis extraction had a higher extraction rate with good protein-lipid separation as observed by optical microscope. Furthermore, subsequent experiments determined neutrase to be the best hydrolytic enzyme in terms of extraction rate and cost. The extraction conditions of neutrase hydrolysis were optimized by single-factor experiment and response surface analysis, and the optimal extraction rate was 58.40 ± 0.25% with the following conditions: enzyme concentration 2,000 IU/g, extraction time 1.0 h, liquid-solid ratio 1.95:1, extraction temperature 40.5℃ and pH 6.5. The fatty acids composition in fish oil from optimized extraction condition was composed of 19.75% saturated fatty acids and 80.25% unsaturated fatty acids. The content of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 8.06% and 1.19%, respectively, with the ratio (6.77:1) surpassed to the recommendation in current researches (5:1). The results in this study suggest protease treatment is an efficient method for high-quality fish oil extraction from Lophius litulon liver with a satisfactory ratio of DHA and EPA.

Research on crack behavior of recycled concrete beams under short-term loading

Zhiheng Deng,Yumei Wang,Haifeng Yang,Jian Qian 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.5

An experimental investigation was conducted to study the crack behavior of beams constructed with Recycled Concrete Aggregate(RCA). This experimental program consisted of 16 beams. The test parameters for this study include RCA replacement ratio andlongitudinal reinforcement ratio. The flexural properties and crack behaviors of the beams were evaluated based on present designcodes. It is found that the use of RCA does not cause an observable change in the progression of flexural strength and crack pattern. However, results of these statistical tests show that the RCA beams possess a larger crack width compares with the conventionalbeams.

Strength and Constitutive Model of Recycled Concrete under Biaxial Compression

Zhiheng Deng,Jun Sheng,Yumei Wang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

The mechanical properties of recycled concrete under biaxial compression were tested in this study. Five grades of replacement ratio of recycled coarse aggregate (0%, 30%, 50%, 70%, 100%) and four groups of stress ratio (−0.25:−1, −0.5:−1, −0.75:−1, −1:−1) were designed to evaluate their influence on mechanical properties .The strength and deformation values of concrete specimens were tested by servo-controlled static-dynamic triaxial machine (TAWZ-5000/3000). The result shows that the stress and strain of recycled oncrete under biaxial compression were both higher than the corresponding values that under uniaxial compression. The stress ratio and recycled aggregate ratio have different effects on mechanical properties of concrete. The initial elastic modulus was also affected by the two factors. Based on the analysis of the test data and combined with the stress-strain curve, a constitutive model for recycled concrete under biaxial compressive state was proposed. The comparison between the test results and the fitted curves shows that the proposed model can suitably describe the stress-strain relationship for recycled concrete.

Use of software-defined radio receivers in two-way satellite time and frequency transfers for UTC computation

Jiang, Zhiheng,Zhang, Victor,Huang, Yi-Jiun,Achkar, Joseph,Piester, Dirk,Lin, Shinn-Yan,Wu, Wenjun,Naumov, Andrey,Yang, Sung-hoon,Nawrocki, Jerzy,Sesia, Ilaria,Schlunegger, Christian,Yang, Zhiqiang,Fu BUREAU INTERNATIONAL DES POIDS ET MESURES 2018 METROLOGIA -BERLIN- Vol.55 No.5

<P>Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal time (UTC). About 20 timing laboratories around the world continuously operate TWSTFT using satellite time and ranging equipment (SATRE<SUP>19</SUP>) modems for remote time and frequency comparisons in this context. The precision of the SATRE TWSTFT as observed today is limited by an apparent daily variation pattern (diurnal) in the TWSTFT results. The observed peak-to-peak variation have been found as high as 2 ns in some cases. Investigations into the origins of the diurnals have so far provided no complete understanding about the cause of the diurnals. One major contributor to the diurnals, however, could be related to properties of the receive part in the modem. In 2014 and 2015, it was demonstrated that bypassing the receive part and the use of software-defined radio (SDR) receivers in TWSTFT ground stations (SDR TWSTFT) instead could considerably reduce both the diurnals and the measurement noise.</P> <P>In 2016, the International Bureau of Weights and Measures (BIPM) and the Consultative Committee for Time and Frequency (CCTF) working group (WG) on TWSTFT launched a pilot study on the application of SDR receivers in the TWSTFT network for UTC computation.</P> <P>The first results of the pilot study were reported to the CCTF WG on TWSTFT annual meeting in May 2017, demonstrating that SDR TWSTFT shows superior performance compared to that of SATRE TWSTFT for practically all links between participating stations. In particular, for continental TWSTFT links, in which the strongest diurnals appear, the use of SDR TWSTFT results in a significant suppression of the diurnals by a factor of between two and three. For the very long inter-continental links, e.g. the Europe-to-USA links where the diurnals are less pronounced, SDR TWSTFT achieved a smaller but still significant gain of 30%. These findings are supported by an evaluation of some of the links with an alternate technique based on GPS signals (GPS IPPP) as reported in this paper.</P> <P>Stimulated by these results, the WG on TWSTFT prepared a recommendation for the 21st CCTF meeting, which proposed the introduction of SDR TWSTFT in UTC generation. With CCTF approval of the recommendation, a roadmap was developed for the implementation of SDR TWSTFT in UTC generation. In accordance with the roadmap, most of the stations that participated in the pilot study have updated the SDR TWSTFT settings to facilitate the use of SDR TWSTFT data in UTC generation. In addition, the BIPM conducted a final evaluation to validate the long-term stability of SDR TWSTFT links, made test runs using the BIPM standard software for the calculation of UTC, now including SDR TWSTFT data, and started to calculate SDR TWSTFT time links as backup from October 2017. The use of SDR TWSTFT in UTC generation will begin in 2018.</P>

Effects of the Microstructure of Copper Through-Silicon Vias on their Thermally Induced Linear Elastic Mechanical Behavior

ZhiYong Wu,Zhiheng Huang,Yucheng Ma,Hua Xiong,Paul P. Conway 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

Through-silicon vias (TSVs) have been investigated extensively in recent years. However, the physical mechanisms behind some of the common problems associated with TSVs, such as the protrusion of Cu vias, are still unknown. In addition, since the dimensions of TSVs have been shrunk to microscopic levels, the sizes of the microstructural features of TSVs are no longer small compared to the dimensions of the vias. Therefore, the role and importance of the microstructural features of TSVs need to be studied to enable more accurate reliability predictions. This study focused on the effects the microstructural features of TSVs, i.e., the Cu grains and their [111] texture, grain size distribution, and morphology, have on the thermally induced linear elastic behavior of the vias. The results of the study indicate that stress distribution in the model that takes into account the Cu grains, whose Young’s moduli and Poisson’s ratios are set according to their crystallographic orientations, is more heterogeneous than that in a reference model in which the bulk properties of Cu are used. Stresses as high as 250 MPa are observed in the via of the model that takes into consideration the Cu grains, while stresses in the via of the reference model are all lower than 150 MPa. In addition, smaller Cu grains in the vias result in higher stresses; however, the variation in stress owning to changes in the grain size is within 20 MPa. The frequency of the stresses ranging from 80 MPa to 100 MPa was the highest in the stress distribution of the vias, depending on boundary conditions. The stress level in the vias decreases with the decrease in the number of grains with the [111] texture. Finally, the stress level is lower in the model in which the grain structure is generated using a phase field model and is closer to that of the microstructures present in real materials.

Bond Strength between Recycled Concrete and Rebar under Stirrup Constraint after Freeze-thaw Cycles

Zuohua Li,Zhiheng Deng,Haifeng Yang,Zhiyu Tang,Wei Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

In cold regions, freeze-thaw (F-T) damage is the main detriment to the durability of reinforced concrete structures, which will reduce the bond performance between concrete and rebar, and then adversely affect the bearing capacity and stiffness of structures. In this study, 21 groups of tests were performed to analyze the effects of the number of F-T cycles, volume stirrup ratio, and replacement percentage of recycled aggregate on the bond performance between recycled aggregate concrete and deformed rebar. The stirrup stress during the pulling process was measured using strain gauges attached to the stirrup surface, and the contribution of the stirrup to the bond strength was analyzed. The results showed that the F-T damage and stirrup constraints could affect the failure mode, the bond strength and the peak slip of pullout specimen. The failure mode of specimen with stirrups could be determined by splitting angle index. The indirect contribution of stirrup accounts for 14 − 25% of the bond strength and increases with the increase in F-T damage. The full bond-slip curve was obtained by fitting four parameters including splitting tensile strength, constraint coefficient, splitting angle index and brittleness index.

Wind-induced fragility assessment of urban trees with structural uncertainties

Yongbo Peng,Zhiheng Wang,Xiaoqiu Ai 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.26 No.1

Wind damage of urban trees arises to be a serious issue especially in the typhoon-prone areas. As a family of tree species widely-planted in Southeast China, the structural behaviors of Plane tree is investigated. In order to accommodate the complexities of tree morphology, a fractal theory based finite element modeling method is proposed. On-site measurement of Plane trees is performed for physical definition of structural parameters. It is revealed that modal frequencies of Plane trees distribute in a manner of grouped dense-frequencies; bending is the main mode of structural failure. In conjunction with the probability density evolution method, the fragility assessment of urban trees subjected to wind excitations is then proceeded. Numerical results indicate that small-size segments such as secondary branches feature a relatively higher failure risk in a low wind level, and a relatively lower failure risk in a high wind level owing to windward shrinks. Besides, the trunk of Plane tree is the segment most likely to be damaged than other segments in case of high winds. The failure position tends to occur at the connection between trunk and primary branches, where the logical protections and reinforcement measures can be implemented for mitigating the wind damage.