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Stability and wrinkling of defective graphene sheets under shear deformation
Te-Hua Fang,Win-Jin Chang,Kai-Peng Lin,Siu-Tsen Shen 한국물리학회 2014 Current Applied Physics Vol.14 No.4
The molecular dynamic simulation is performed to study the wrinkling behavior of a graphene sheet with a hole subjected to a shear loading at different temperatures. Wrinkling is inevitable under pure shear loading. Four different hole diameters of 0, 0.8, 1.6, and 3.2 nm are chosen in this simulation. The results show that the number of ridges increases with an increase of the width of the graphene sheet. The shear stress induced in the defective graphene sheet increases with increasing temperature. In addition, the shear modulus of the defective graphene sheet also increases with an increase of temperature.
Experimental Study on Load-Bearing Capacities of Frame-Type Scaff olds Used in Precast Construction
Jui-LinPeng,Pao-Li Wang,Siu-Lai Chan,Po-Kai Wu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.2
In precast construction, because the precast beams are broader and the frame-type steel scaffolds need to bear more weight, such as that of the precast slabs and precast beams, the dimensions and load-bearing capacities of the frame-type steel scaffolds are different from those of traditional door-type steel scaffolds. The results of this study show that based on the load-bearing capacities of the five different combined setups of frame-type steel scaffolds used in this study, the horizontal members of the square-type and rectangle-type steel scaffolds are able to enhance the load-bearing capacities of the combined setups of the frame-type steel scaffolds. Therefore, when adopting combined setups of frame-type steel scaffolds, it is advisable to refrain from using only door-type steel scaffolds on construction sites. The ability of jack bases to enhance the load-bearing capacities of frame-type steel scaffolds is not significant. Under the condition of an eccentric load located at one-third of both the x-axis and y-axis, the load-bearing capacity of the frame-type steel scaffolds reduces to 60% of that when no eccentric load is involved. When a lateral force is applied, the critical load of frame-type steel scaffolds decreases with increasing lateral forces.
Zhang, Lin-Hao,Wang, You-Wu,Ni, Yi-Qing,Lai, Siu-Kai Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.5
High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train's operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.
Tay, Roland Yingjie,Park, Hyo Ju,Lin, Jinjun,Ng, Zhi Kai,Jing, Lin,Li, Hongling,Zhu, Minmin,Tsang, Siu Hon,Lee, Zonghoon,Teo, Edwin Hang Tong American Chemical Society 2018 Chemistry of materials Vol.30 No.19
<P>Spiral growth of various nanomaterials including some two-dimensional (2D) transition metal dichalcogenides had recently been experimentally realized using chemical vapor deposition (CVD). However, such growth that is driven by screw dislocation remained elusive for graphene and is rarely discussed because of the use of metal catalysts. In this work, we show that formation of few-layer graphene (FLG) with a spiral structure driven by screw dislocation can be obtained alongside FLG having a concentric layered structure formed by interfacial nucleation (nucleation at the graphene/Cu interface) using Cu-catalyzed ambient pressure CVD. Unlike commonly reported FLG grown by interfacial nucleation where the second layer is grown independently beneath the first, the growth of a spiral structure adopts a top growth mechanism where the top layers are an extension from the initial monolayer which spirals around an axial dislocation in self-perpetuating steps. Since the same atomic orientation is preserved, the subsequent spiraling layers are stacked in an oriented AB-stacked configuration. This contrasts with FLG formed by interfacial nucleation where turbostratic stacking of the entire adlayer may exist. In both growth scenarios, the second layer (either top or bottom) can grow across the grain boundaries of the initial monolayer domains, forming partial regions with turbostratic stacking configuration due to weak interlayer van der Waals interactions. The unique interlayer coupling of FLG spirals, which enable superior conductivity along the normal of the 2D crystal with spiraling trajectories, are expected to have new and interesting nanoscale applications.</P> [FIG OMISSION]</BR>
Current Status and Growth of Nuclear Theranostics in Singapore
Hian Liang Huang,Aaron Kian Ti Tong,Sue Ping Thang,Sean Xuexian Yan,Winnie Wing Chuen Lam,Kelvin Siu Hoong Loke,Charlene Yu Lin Tang,Lenith Tai Jit Cheng,Gideon Su Kai Ooi,Han Chung Low,Butch Maulion 대한핵의학회 2019 핵의학 분자영상 Vol.53 No.2
The concept of theranostics, where individual patient-level biological information is used to choose the optimal therapy for that individual, has become more popular in the modern era of ‘personalised’ medicine. With the growth of theranostics, nuclear medicine as a specialty is uniquely poised to grow along with the ever-increasing number of concepts combining imaging and therapy. This special report summarises the status and growth of Theranostic Nuclear Medicine in Singapore.We will cover our experience with the use of radioiodine, radioiodinated metaiodobenzylguanidine, peptide receptor radionuclide therapy, prostate specific membrane antigen radioligand therapy, radium-223 and yttrium-90 selective internal radiation therapy.We also include a section on our radiopharmacy laboratory, crucial to our implementation of theranostic principles. Radionuclide theranostics has seen tremendous growth and we hope to be able to grow alongside to continue to serve the patients in Singapore and in the region.
Chi-Ho Lee,Mei-Zhen Wu,David Tak-Wai Lui,Darren Shing-Hei Chan,Carol Ho-Yi Fong,Sammy Wing-Ming Shiu,Ying Wong,Alan Chun-Hong Lee,Joanne King-Yan Lam,Yu-Cho Woo,Karen Siu-Ling Lam,Kelvin Kai-Hang Yiu 대한당뇨병학회 2022 Diabetes and Metabolism Journal Vol.46 No.6
Background: Insulin-treated patients with long duration of type 2 diabetes mellitus (T2DM) are at increased risk of ketoacidosis related to sodium-glucose co-transporter 2 inhibitor (SGLT2i). The extent of circulating ketone elevation in these patients remains unknown. We conducted this study to compare the serum ketone response between dapagliflozin, an SGLT2i, and sitagliptin, a dipeptidyl peptidase-4 inhibitor, among insulin-treated T2DM patients.Methods: This was a randomized, open-label, active comparator-controlled study involving 60 insulin-treated T2DM patients. Participants were randomized 1:1 for 24-week of dapagliflozin 10 mg daily or sitagliptin 100 mg daily. Serum β-hydroxybutyrate (BHB) levels were measured at baseline, 12 and 24 weeks after intervention. Comprehensive cardiometabolic assessments were performed with measurements of high-density lipoprotein cholesterol (HDL-C) cholesterol efflux capacity (CEC), vibration-controlled transient elastography and echocardiography.Results: Among these 60 insulin-treated participants (mean age 58.8 years, diabetes duration 18.2 years, glycosylated hemoglobin 8.87%), as compared with sitagliptin, serum BHB levels increased significantly after 24 weeks of dapagliflozin (P=0.045), with a median of 27% increase from baseline. Change in serum BHB levels correlated significantly with change in free fatty acid levels. Despite similar glucose lowering, dapagliflozin led to significant improvements in body weight (P=0.006), waist circumference (P=0.028), HDL-C (P=0.041), CEC (P=0.045), controlled attenuation parameter (P=0.007), and liver stiffness (P=0.022). Average E/e’, an echocardiographic index of left ventricular diastolic dysfunction, was also significantly lower at 24 weeks in participants treated with dapagliflozin (P=0.037).Conclusion: Among insulin-treated T2DM patients with long diabetes duration, compared to sitagliptin, dapagliflozin modestly increased ketone levels and was associated with cardiometabolic benefits.