An empirical model for amplitude prediction on VIV-galloping instability of rectangular cylinders

Niu, Huawei,Zhou, Shuai,Chen, Zhengqing,Hua, Xugang Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.21 No.1

Aerodynamic forces of vortex-induced vibration and galloping are going to be coupled when their onset velocities are close to each other, which will induce the cross-wind amplitudes of the structures increased continuously with ever-increasing wind velocities. The main purpose of the present work is going to propose an empirical formula to predict the response amplitude of VIV-galloping interaction. Firstly, two typical mathematical models for the coupled oscillations, i.e., Tamura & Shimada model and Parkinson & Corless model are comparatively summarized. Then, the key parameter affecting response amplitude is determined through comparative numerical simulations with Tamura & Shimada model. For rectangular cylinders with the side ratio from 0.5 to 2.5, which are actually prone to develop the VIV and galloping induced interaction responses, an empirical amplitude prediction formula is proposed after regression analysis on comprehensively collected experimental data with the predetermined key parameter.

Effect of Water Content on Dynamic Fracture Characteristic of Rock under Impacts

Caoyuan Niu,Zheming Zhu,Fei Wang,Peng Ying,Shuai Deng 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.1

Water contents in rocks vary with local hydrogeological conditions and may significantly affect the stability of rock mass engineering. For example, geological disasters are usually occurring after rainfall, such as landslides, karst collapse. In this paper, drop plate impact (DPI) tests were performed on single cleavage triangle (SCT) red sandstone specimens with dry, natural, absorbed and saturated conditions, which has a great guiding significance for deep understandingof dynamic failure of rock materials. The crack initiation time was obtained by crack propagation gauges (CPGs), and crack propagation speeds were computed by fractal method. The dynamic stress intensity factors (DSIFs) were calculated by ABAQUS code. Meanwhile, the microstructure of the fracture surface was scanned and was analyzed. The results show that the average critical DSIFs and crack propagation speeds vary with water content significantly. For the dry sandstone, the average critical DSIF is the highest, whereas the average crack speed is the lowest. For the natural sandstone, the average critical DSIF is the lowest, whereas the average crack speed is the highest. For the water-bearing sandstone, i.e., the natural, absorbed and saturated sandstone, the average critical DSIF increases with water content, whereas the crack speed decreases with increasing water content.

An empirical model for amplitude prediction on VIV-galloping instability of rectangular cylinders

Huawei Niu,Zhengqing Chen,Xugang Hua,Shuai Zhou 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.21 No.1

Aerodynamic forces of vortex-induced vibration and galloping are going to be coupled when their onset velocities are close to each other, which will induce the cross-wind amplitudes of the structures increased continuously with ever-increasing wind velocities. The main purpose of the present work is going to propose an empirical formula to predict the response amplitude of VIV-galloping interaction. Firstly, two typical mathematical models for the coupled oscillations, i.e., Tamura & Shimada model and Parkinson & Corless model are comparatively summarized. Then, the key parameter affecting response amplitude is determined through comparative numerical simulations with Tamura & Shimada model. For rectangular cylinders with the side ratio from 0.5 to 2.5, which are actually prone to develop the VIV and galloping induced interaction responses, an empirical amplitude prediction formula is proposed after regression analysis on comprehensively collected experimental data with the predetermined key parameter.

Pre-harvest ethylene control affects vase life of cut rose ‘Carola’ by regulating energy metabolism and antioxidant enzyme activity

Bi Gong,Shuai Huang,Niu Ye,Xue Yuan,Huiling Ma 한국원예학회 2018 Horticulture, Environment, and Biotechnology Vol.59 No.6

We studied the role of ethylene control in regulating energy metabolism, antioxidant enzyme activity, and vase life of cutrose Rosa hybrida ‘Carola’. Rose fl owers at stage II were sprayed with one of the following solutions: water (control), 10μL L −1 1-methylcyclopropene (1-MCP), or 0.5 g L −1 2-chloroethanephosphonic acid (ethephon). After harvest, ethyleneproduction rate, respiration intensity, energy charge (EC), activities of energy metabolism-related and antioxidant enzymes,and malondialdehyde (MDA) content were measured. Results showed that 1-MCP enhanced the activities of superoxidedismutase, H + -adenosine triphosphatase, Ca 2+ -adenosine triphosphatase, succinic dehydrogenase, and cytochrome c oxidase,increased adenosine triphosphate (ATP) content, maintained high EC levels, inhibited respiration intensity, reduced peroxidase(POD) and polyphenol oxidase (PPO) activity and MDA accumulation, and prolonged vase life. Ethephon promotedethylene production and respiration intensity, increased POD and PPO activity, reduced ATP content and EC levels, andaccelerated senescence. Our results support a novel role for ethylene control in regulating senescence of ‘Carola’.

FNC inhibits non-small cell lung cancer by activating the mitochondrial apoptosis pathway

Jing Xiang,Niu Shuai,Liang Yi,Chen Huiping,Wang Ning,Peng Youmei,Ma Fang,Yue Wanying,Wang Qingduan,Chang Junbiao,Zhang Yi,Zhang Yan 한국유전학회 2022 Genes & Genomics Vol.44 No.1

Background: Previously, we published that 4'-azid-2'-deoxy-2'-fluorarabinoside (FNC), a novel cytosine nucleoside analog, has good anti-viral and anti-tumor activity. Objective: This study aimed to further explore the role and molecular mechanism of FNC in non-small cell lung cancer (NSCLC). Methods: FNC was tested in the NSCLC H460 cell line, the Lewis mouse model, and the H460 cell xenograft model. The effects of FNC were assessed by cell viability, transwell migration, and wound scratch analyses of cell migration and invasion. Apoptosis was assessed by flow cytometry. Proteins expression was assessed by western blot and immunohistochemistry staining (IHC). Results: FNC inhibits the proliferation and metastasis of H460 cells in a time- and dose-dependent manner. FNC treatment showed efficacy and low toxicity in the Lewis mouse lung cancer model as well as in the H460 cell xenograft model. Further, FNC induced H460 cell apoptosis through the activation of the mitochondrial pathway. Notably, FNC inhibited invasion by increasing E-cadherin protein and reducing the protein expression of VEGF, MMP-2, MMP-9, and CD31. Conclusion: FNC inhibits NSCLC by activating the mitochondrial apoptosis pathway and regulating the expressions of multiple proteins related to cell adhesion and invasion, highlighting its potential as an NSCLC therapeutic.

Differential responses of walnut cultivars to cold storage and their correlation with postharvest physiological parameters

Xue Yuan,Shuai Huang,Huiling Ma,Ning Huang,Niu Ye 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.3

In this study, we screened eight walnut ( Juglans regia L.) cultivars (‘Xifu2’, ‘Shaanhe’, ‘Weina’, ‘Xiangling’, ‘Xiluo3’,‘Xifu1’, ‘Liaoning4’, and ‘Qingxiang’) in order to establish reliable selection criteria for storage-tolerance. Fresh walnutfruit were stored at 0 ± 0.5 °C and 70–80% relative humidity. Browning index, postharvest physio-biochemical characteristics,acid value, and sensory quality were measured. The results showed that ‘Xifu2’, ‘Shaanhe’, and ‘Weina’ developedbrowning early and quickly and storage was terminated for these cultivars at 60 days. ‘Xiluo3’, ‘Xifu1’, ‘Liaoning4’, and‘Qingxiang’ had a slow browning rate and storage was terminated at 72 days. ‘Xiangling’ developed browning at a mediumrate and storage was terminated at 72 days. Correlation analysis suggested that the terminal browning index of each cultivarpositively correlated with lipoxygenase activity at 18 days of storage, polyphenol oxidase activity at 18–30 days, malondialdehydecontent at 18 days, and the respiration rate at 42 days, while it negatively correlated with the total phenolic contentat 18 days and phenylalanine ammonia lyase activity at 12 days. The storage tolerance of each cultivar was evaluatedaccording to the terminal browning index, acid value, and sensory quality. Comprehensive evaluation and cluster analysiswere performed to rank the cold storage tolerance of the eight cultivars as follows: ‘Qingxiang’ and ‘Xifu1’ > ‘Liaoning4’and ‘Xiluo3’ > ‘Xifu2’ and ‘Xiangling’ > ‘Shaanhe’ and ‘Weina’. In conclusion, cultivars used for fresh in-husk walnut fruitwith lower levels of membrane peroxidation and phenol oxidation, and higher level of phenol synthesis around 18 days ofstorage would be suitable candidates for cold storage. ‘Qingxiang’ and ‘Xifu1’ were selected as storage-tolerant cultivars.

Numerical Simulation on Damage and Failure Mechanism of Rock under Combined Multiple Strain Rates

Zhu, Wancheng,Wei, Jiong,Niu, Leilei,Li, Shuai,Li, Shaohua WILEY-INTERSCIENCE 2018 SHOCK AND VIBRATION Vol.2018 No.-

<P>During underground hard-rock mining, the drilling and blasting method currently remains the most economical excavation method, and the rock may experience a multistrain-rate spectrum under quasi-static, dynamic, and rheological loading conditions and their combination as well. The study on the damage mechanism of rock under multistrain-rate condition that induced by mining excavation is the fundamental issue for predicting the mining-induced hazards such as rockburst. In this study, the state of the art of rock damage and failure under different strain rates is reviewed first. Then, the numerical model for rock failure under multiple strain rates is formulated when the rock damage is taken as the main thread. Meanwhile, we summarize our work in this area over the past ten years, and the constitutive law for the damage and failure of rock under multistrain rates is presented. Finally, several numerical examples, i.e., rock damage and failure under combined static and dynamic load, rock damage and failure triggered by dynamic stress redistribution due to excavation, rock damage and failure induced by blasting, and rock damage and failure due to the combination of dynamic disturbance and rheological load, are presented. Based on these numerical simulations, the associated rock damage mechanism and failure behaviors under differently combined multiple strain rates are clarified, which may provide a theoretical basis for clarifying the rock failure mechanism during rockbursts and rock blasting. Also, further studies on the damage and failure of rock under multiple strain rates are suggested.</P>

Protein-based soft micro-optics fabricated by femtosecond laser direct writing

Sun, Yun-Lu,Dong, Wen-Fei,Niu, Li-Gang,Jiang, Tong,Liu, Dong-Xu,Zhang, Lu,Wang, Ying-Shuai,Chen, Qi-Dai,Kim, Dong-Pyo,Sun, Hong-Bo Nature Publishing Group 2014 Light, science & applications Vol.3 No.1

<P>In this work, we report a novel soft diffractive micro-optics, called 'microscale kinoform phase-type lens (micro-KPL)', which is fabricated by femtosecond laser direct writing (FsLDW) using bovine serum albumin (BSA) as building blocks and flexible polydimethylsiloxane (PDMS) slices as substrates. By carefully optimizing various process parameters of FsLDW (e. g., average laser power density, scanning step, exposure time on a single point and protein concentration), the as-formed protein micro-KPLs exhibit excellent surface quality, well-defined three-dimensional (3D) geometry and distinctive optical properties, even in relatively harsh operation environments (for instance, in strong acid or base). Laser shaping, imaging and other optical performances can be easily achieved. More importantly, micro-KPLs also have unique flexible and stretchable properties as well as good biocompatibility and biodegradability. Therefore, such protein hydrogel-based micro-optics may have great potential applications, such as in flexible and stretchable photonics and optics, soft integrated optical microsystems and bioimplantable devices.</P>