Investigation on the effect of vibration frequency on vortex-induced vibrations by section model tests

Hua, X.G.,Chen, Z.Q.,Chen, W.,Niu, H.W.,Huang, Z.W. Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

Higher-mode vertical vortex-induced vibrations (VIV) have been observed on several steel box-girder suspension bridges where different vertical modes are selectively excited in turn with wind velocity in accordance with the Strouhal law. Understanding the relationship of VIV amplitudes for different modes of vibration is very important for wind-resistant design of long-span box-girder suspension bridges. In this study, the basic rectangular cross-section with side ratio of B/D=6 is used to investigate the effect of different modes on VIV amplitudes by section model tests. The section model is flexibly mounted in wind tunnel with a variety of spring constants for simulating different modes of vibration and the non-dimensional vertical amplitudes are determined as a function of reduced velocity U/fD. Two 'lock-in' ranges are observed at the same onset reduced velocities of approximately 4.8 and 9.4 for all cases. The second 'lock-in' range, which is induced by the conventional vortex shedding, consistently gives larger responses than the first one and the Sc-normalized maximum non-dimensional responses are almost the same for different spring constants. The first 'lock-in' range where the vibration frequency is approximately two times the vortex shedding frequency is probably a result of super-harmonic resonance or the "frequency demultiplication". The main conclusion drawn from the section model study, central to the higher-mode VIV of suspension bridges, is that the VIV amplitude for different modes is the same provided that the Sc number for these modes is identical.

Synthesis and Biological Evaluation of Heterocyclic Ring-substituted Chalcone Derivatives as Novel Inhibitors of Protein Tyrosine Phosphatase 1B

Chen, Zhen-Hua,Sun, Liang-Peng,Zhang, Wei,Shen, Qiang,Gao, Li-Xin,Li, Jia,Piao, Hu-Ri Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.5

Protein tyrosine phosphatase 1B (PTP1B) is a key factor in negative regulation of the insulin pathway, and is a promising target for the treatment of type-II diabetes, obesity and cancer. Herein, compound ($\mathbf{4}$) was first observed to have moderate inhibitory activity against PTP1B with an $IC_{50}$ value of $13.72{\pm}1.53{\mu}M$. To obtain more potent PTP1B inhibitors, we synthesized a series of chalcone derivatives using compound ($\mathbf{4}$) as the lead compound. Compound $\mathbf{4l}$ ($IC_{50}=3.12{\pm}0.18{\mu}M$) was 4.4-fold more potent than the lead compound $\mathbf{4}$ ($IC_{50}=13.72{\pm}1.53{\mu}M$), and more potent than the positive control, ursolic acid ($IC_{50}=3.40{\pm}0.21{\mu}M$). These results may help to provide suitable drug-like lead compounds for the design of inhibitors of PTP1B as well as other PTPs.

Characteristics and heterostructure of metal-doped TiO2/ZnO nanocatalysts

Chen Wu-Jhang,Hsu Kuo-Chin,Fang Te-Hua,Chen Tao-Hsing,Li Ming-Hao 한국물리학회 2022 Current Applied Physics Vol.38 No.-

In this study, Ag or Al-doped TiO2/ZnO heterostructure nanocatalysts were prepared using a sol-gel method for photocatalysis to evaluate the degradability. The photocatalytic behavior was evaluated by the degradation of methylene blue (MB) under ultraviolet (UV) light irradiation. Photocatalytic studies suggested that 1 mol% Agdoped TiO2/ZnO (TiO2/ZnO = 0.75/0.25) heterostructure nanocatalysts showed higher photocatalytic activity, and that the degradation efficiency can reach 83% in 4 h, 14% higher than that for pure TiO2. Finally, the photocatalysis mechanism for the Ag-doped TiO2/ZnO heterostructure nanocatalysts is discussed.

Bayberry Tannin as Stabilizer for the Synthesis of Highly Active and Reusable Heterogeneous Pd Catalysts and Their Application in the Catalytic Hydrogenation of Olefins

Chen, Chen,Lv, Guang,Huang, Xin,Liao, Xue Pin,Zhang, Wen Hua,Shi, Bi Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.2

In this study, the homogenous Pd nanoparticles (Pd NPs) were first prepared with bayberry tannin (BT) as the stabilizers. Subsequently, the obtained bayberry tannin-stabilized Pd nanoparticles (BT-Pd) were immobilized onto ${\gamma}-Al_2O_3$ to prepare heterogeneous ${\gamma}-Al_2O_3$-BT-Pd catalysts. Fourier Transformation Infrared Spectrum (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses confirmed that the Pd NPs were well stabilized by the phenolic hydroxyl groups of BT. Transmission Electron Microscopy (TEM) observation indicated that the diameter of the Pd NPs can be effectively controlled in the range of 4.2-16.0 nm by varying the amount of BT. It is found that the ${\gamma}-Al_2O_3$-BT-Pd catalysts exhibit highly activity for various olefin hydrogenations. For example, the initial TOF (turnover frequency) of the ${\gamma}-Al_2O_3$-BT-Pd in the allyl alcohol hydrogenation is as high as $12804 mol{\cdot}mol^{-1}{\cdot}h^{-1}$. Furthermore, the ${\gamma}-Al_2O_3$-BT-Pd can be reused 5 times without significant loss of activity, exhibiting a superior reusability as compared with conventionally prepared ${\gamma}-Al_2O_3$-Pd catalysts.

Synthesis, properties, calculations and applications of small molecular host materials containing oxadiazole units with different nitrogen and oxygen atom orientations for solution-processable blue phosphorescent OLEDs

Hua Ye,Hongyu Wu,Liangyuan Chen,Songhua Ma,Kaifeng Zhou,Guobing Yan,Jiazhong Shen,Dongcheng Chen,Shi‑Jian Su 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.2

A series of new small molecules based on symmetric electron-acceptor of 1,3,4-oxadiazole moiety or its asymmetric isomerof 1,2,4-oxadiazole unit were successfully synthesized and applied to solution-processable blue phosphorescent organic lightemittingdiodes for the first time, and their thermal, photophysical, electrochemical properties and density functional theorycalculations were studied thoroughly. Due to the high triplet energy levels (ET, 2.82–2.85 eV), the energy from phosphorescentemitter of iridium(III) bis[(4,6-difluorophenyl)-pyridinate-N,C2′]picolinate (FIrpic) transfer to the host molecules couldbe effectively suppressed and thus assuring the emission of devices was all from FIrpic. In comparison with the para-modeconjugation in substitution of five-membered 1,3,4-oxadiazole in 134OXD, the meta-linkages of 1,2,4-isomer appending withtwo phenyl rings cause the worse conjugation degree and the electron delocalization as well as the lower electron-withdrawingability for the other 1,2,4-oxadiazole-based materials. Noting that the solution-processed device based on 134OXD containing1,3,4-oxadiazole units without extra vacuum thermal-deposited hole/exciton-blocking layer and electron-transportinglayer showed the highest maximum current efficiency (CEmax) of 8.75 cd/A due to the excellent charge transporting ability of134OXD, which far surpassed the similar devices based on other host materials containing 1,2,4-oxadiazole units. Moreover,the device based on 134OXD presented small efficiency roll-off with current efficiency (CE) of 6.26 cd/A at high brightnessup to 100 cd/m2. This work demonstrates different nitrogen and oxygen atom orientations of the oxadiazole-based hostmaterials produce major impact on the optoelectronic characteristics of the solution-processable devices.

Associations of Plasma Glucagon Levels with Estimated Glomerular Filtration Rate, Albuminuria and Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus

Hua-Xing Huang,Liang-Lan Shen,Hai-Yan Huang,Li-Hua Zhao,Feng Xu,Dong-Mei Zhang,Xiu-Lin Zhang,Tong Chen,Xue-Qin Wang,Yan Xie,Jian-Bin Su 대한당뇨병학회 2021 Diabetes and Metabolism Journal Vol.45 No.6

Background: Type 2 diabetes mellitus (T2DM) is characterized by elevated fasting glucagon and impaired suppression of postprandial glucagon secretion, which may participate in diabetic complications. Therefore, we investigated the associations of plasma glucagon with estimated glomerular filtration rate (eGFR), albuminuria and diabetic kidney disease (DKD) in T2DM patients.Methods: Fasting glucagon and postchallenge glucagon (assessed by area under the glucagon curve [AUCgla]) levels were determined during oral glucose tolerance tests. Patients with an eGFR <60 mL/min/1.73 m2 and/or a urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g who presented with diabetic retinopathy were identified as having DKD.Results: Of the 2,436 recruited patients, fasting glucagon was correlated with eGFR and UACR (r=–0.112 and r=0.157, respectively; P<0.001), and AUCgla was also correlated with eGFR and UACR (r=–0.267 and r=0.234, respectively; P<0.001). Moreover, 31.7% (n=771) presented with DKD; the prevalence of DKD was 27.3%, 27.6%, 32.5%, and 39.2% in the first (Q1), second (Q2), third (Q3), and fourth quartile (Q4) of fasting glucagon, respectively; and the corresponding prevalence for AUCgla was 25.9%, 22.7%, 33.7%, and 44.4%, respectively. Furthermore, after adjusting for other clinical covariates, the adjusted odds ratios (ORs; 95% confidence intervals) for DKD in Q2, Q3, and Q4 versus Q1 of fasting glucagon were 0.946 (0.697 to 1.284), 1.209 (0.895 to 1.634), and 1.521 (1.129 to 2.049), respectively; the corresponding ORs of AUCgla were 0.825 (0.611 to 1.114), 1.323 (0.989 to 1.769), and 2.066 (1.546 to 2.760), respectively. Additionally, when we restricted our analysis in patients with glycosylated hemoglobin <7.0% (n=471), we found fasting glucagon and AUCgla were still independently associated with DKD.Conclusion: Both increased fasting and postchallenge glucagon levels were independently associated with DKD in T2DM patients.

Effect of Tissue Engineering Small Vessel Scaffolds in Experimental Animals

( Hua Yong Chen ),( Shu Ling Bai ),( Ying Qing Chen ) 한국조직공학·재생의학회 2012 조직공학과 재생의학 Vol.9 No.3

Acellular xenogeneic small vessel scaffolds preliminarily eliminate the xenogeneic antigen that could induce an immune rejection. We transplanted the Wistar rat caudal artery scaffolds into Japanese white rabbit ear central arteries, and observed the changes of blood flow and vessel wall. We acquired 30 caudal arteries from 15 Wistar rats, some were directly assigned as caudal artery group, the others were disposed by 1% p-octyl polyethelene glycol phenyl ether, and were assigned as the group of tissue engineered small vessel scaffold. We collected 15 Japanese white rabbits, and utilized a pair of ear central arteries per rabbit as hosts. Through microscopic surgery, the proximal broken end of central artery was overlapped into the donor`s proximal vessel lumen by sleeve anastomosis, while the distal broken end was sutured by classical end-to-end anastomosis. The maximum patency time of small vessel scaffold was 46 hours and 47 minutes, and which of caudal vessel was 14 hours. The poor blood flow primarily was occurred in distal broken end, while proximal end was connected in pedicle graft structure. On the 10th day, tunica intima fibers in vessel scaffold were still arranged in cylindrical conformation regularly without cell adherence. On the 100th day, tunica intima fibers were still preserved completely in proximal end. The results showed that xenogeneic acellular small vessel scaffold can be transplanted into the host, and the sleeve anastomosis was significantly superior to the classical end-to-end anastomosis.

Mode shape expansion with consideration of analytical modelling errors and modal measurement uncertainty

Chen, Hua-Peng,Tee, Kong Fah,Ni, Yi-Qing Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.10 No.4

Mode shape expansion is useful in structural dynamic studies such as vibration based structural health monitoring; however most existing expansion methods can not consider the modelling errors in the finite element model and the measurement uncertainty in the modal properties identified from vibration data. This paper presents a reliable approach for expanding mode shapes with consideration of both the errors in analytical model and noise in measured modal data. The proposed approach takes the perturbed force as an unknown vector that contains the discrepancies in structural parameters between the analytical model and tested structure. A regularisation algorithm based on the Tikhonov solution incorporating the L-curve criterion is adopted to reduce the influence of measurement uncertainties and to produce smooth and optimised expansion estimates in the least squares sense. The Canton Tower benchmark problem established by the Hong Kong Polytechnic University is then utilised to demonstrate the applicability of the proposed expansion approach to the actual structure. The results from the benchmark problem studies show that the proposed approach can provide reliable predictions of mode shape expansion using only limited information on the operational modal data identified from the recorded ambient vibration measurements.

Study of Medium Voltage Electric Bridge Set of the Underground Coal Mine

Chen Wei-hua,Yan Xiao-heng,Peng Ji-shen,Zhang Yan 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.1

Quasiparticle tunneling in the Moore-Read fractional quantum Hall state

Chen, Hua,Hu, Zi-Xiang,Yang, Kun,Rezayi, E. H.,Wan, Xin American Physical Society 2009 Physical review. B, Condensed matter and materials Vol.80 No.23