Browsing by Author "Qin, Chao"
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- Analysis of Tower Shadow Effects on the UAE Rotor BladesNoyes, Carlos; Loth, Eric; Qin, Chao (Virginia Tech, 2015-06)A leading obstacle hindering the development of wind turbines to extreme scale is the structural integrity of the blades. Downwind rotors have been shown to give structural advantages for larger systems. However, there is an added aerodynamic complication from the tower shadow. This paper presents and analyzes a previously unpublished subset of data collected by NREL during an extensive wind tunnel campaign for Unsteady Aerodynamic Experiment Phase VI (UAE Phase VI). The experimental data includes relative flow fields, aerodynamic blade forces, and root blade flapwise bending moments, from upwind turbines, downwind turbines and downwind turbines with the use of an aerodynamic tower fairing. It is shown that the tower shadow can have a severe and negative effect on these variables, leading to higher bending stresses. The use of a tower fairing can greatly reduce these detrimental effects. To better interpret this data, predictions using an aeroelastic wind turbine code, FAST, was used to model the experimental conditions. The differences between the experimental data and the computational predictions are attributed to unsteady effects of the wake. This suggest that wake modeling for downwind turbines may require modifications to capture physically realistic tower shadow effects.
- Dynamics of Small Non-coding RNA Profiles and the Intestinal Microbiome of High and Low Weight ChickensZhou, Hao; Yang, Lingyu; Ding, Jinmei; Xu, Ke; Liu, Jiajia; Zhu, Wenqi; Zhu, Jianshen; He, Chuan; Han, Chengxiao; Qin, Chao; Luo, Huaixi; Chen, Kangchun; Zheng, Yuming; Honaker, Christa F.; Zhang, Yan; Siegel, Paul B.; Meng, He (Frontiers, 2022-06-30)The host and its symbiotic bacteria form a biological entity, holobiont, in which they share a dynamic connection characterized by symbiosis, co-metabolism, and coevolution. However, how these collaborative relationships were maintained over evolutionary time remains unclear. In this research, the small non-coding RNA (sncRNA) profiles of cecum and their bacteria contents were measured from lines of chickens that have undergone long-term selection for high (HWS) or low (LWS) 56-day body weight. The results from these lines that originated from a common founder population and maintained under the same husbandry showed an association between host intestinal sncRNA expression profile (miRNA, lncRNA fragment, mRNA fragment, snoRNA, and snRNA) and intestinal microbiota. Correlation analyses suggested that some central miRNAs and mRNA fragments had interactions with the abundance of intestinal microbial species and microbiota functions. miR-6622-3p, a significantly differentially expressed (DE) miRNA was correlated with a body weight gain related bacterium, Alistipes putredinis. Our results showed that host sncRNAs may be mediators of interaction between the host and its intestinal microbiome. This provides additional clue for holobiont concepts.
- Enzymatic degradation of extracellular DNA exposed to chlorpyrifos and chlorpyrifos-methyl in an aqueous systemYang, Bing; Qin, Chao; Hu, Xiaojie; Xia, Kang; Lu, Chao; Gudda, Fredrick Owino; Ma, Zhao; Gao, Yanzheng (2019-11)The persistence of extracellular DNA (eDNA) is crucial for ensuring species diversity and ecological function in aquatic systems. However, scarce information exists about the impact of pesticides on eDNA, although they often co-exist in the aquatic environment. Using a variety of spectroscopic analyses, eDNA degradation and the associated alterations in DNA secondary structure was investigated by exposing DNase I to tested DNA in the presence of chlorpyrifos, a commonly used organophosphate pesticide. Molecular dynamics simulation was used to explore the weak interactions between the tested DNA and chlorpyrifos. The results indicated that chlorpyrifos significantly enhanced DNA degradation without affecting the enzyme activity of DNase I in an aqueous system. Spectroscopic experiments confirmed that chlorpyrifos and the analog chlorpyrifos-methyl could bind with DNA to cause the bases noncovalent stacking interaction. Molecular simulations further demonstrated that pesticide binding with DNA molecules caused widening of the DNA grooves and destruction of the hydrated layer, which enhanced DNA degradation. The findings presented herein provide novel insight into the genotoxicity and ecotoxicity of chlorpyrifos and chlorpyrifos-methyl, as well as their impacts on DNA persistence in aquatic environments.
- Fe3 +-saturated montmorillonite effectively deactivates bacteria in wastewaterQin, Chao; Chen, Chaoqi; Shang, Chao; Xia, Kang (Elsevier, 2018)Existing water disinfection practices often produce harmful disinfection byproducts. The antibacterial activity of Fe3 +-saturated montmorillonite was investigated mechanistically using municipal wastewater effluents. Bacterial deactivation efficiency (bacteria viability loss) was 92 ± 0.64% when a secondary wastewater effluent was mixed with Fe3 +-saturated montmorillonite for 30 min, and further enhanced to 97 ± 0.61% after 4 h. This deactivation efficiency was similar to that when the same effluent was UV-disinfected before it exited a wastewater treatment plant. Comparing to the secondary wastewater effluent, the bacteria deactivation efficiency was lower when the primary wastewater effluent was exposed to the same dose of Fe3 +-saturated montmorillonite, reaching 29 ± 18% at 30 min and 76 ± 1.7% at 4 h. Higher than 90% bacterial deactivation efficiency was achieved when the ratio between wastewater bacteria population and weight of Fe3 +-saturated montmorillonite was at < 2 × 103 CFU/mg. Furthermore, 99.6–99.9% of total coliforms, E. coli, and enterococci in a secondary wastewater effluent was deactivated when the water was exposed to Fe3 +-saturated montmorillonite for 1 h. Bacterial colony count results coupled with the live/dead fluorescent staining assay observation suggested that Fe3 +-saturated montmorillonite deactivated bacteria in wastewater through two possible stages: electrostatic sorption of bacterial cells to the surfaces of Fe3 +-saturated montmorillonite, followed by bacterial deactivation due to mineral surface-catalyzed bacterial cell membrane disruption by the surface sorbed Fe3 +. Freeze-drying the recycled Fe3 +-saturated montmorillonite after each usage resulted in 82 ± 0.51% bacterial deactivation efficiency even after its fourth consecutive use. This study demonstrated the promising potential of Fe3 +-saturated montmorillonite to be used in applications from small scale point-of-use drinking water treatment devices to large scale drinking and wastewater treatment facilities.
- Investigation of Dynamic Loading for 13.2 MW Downwind Pre-Aligned RotorQin, Chao; Loth, Eric; Lee, Sang; Moriarty, Patrick (Virginia Tech, 2015-06)To alleviate the mass-scaling issues associated with conventional upwind rotors of extreme-scale turbines, a downwind rotor concept is considered that uses fixed coning to align the non-circumferential loads for a given steady-state condition. This alignment can be pre-set to eliminate downwind blade moments for a given steady-state condition at rated wind speed and to minimize them for other conditions. The alleviation in downwind dynamic loads may enable a reduced structural blade mass as compared with a conventional upwind rotor. To examine the potential impact of this design, FAST simulations were conducted for a 13.2 MW rated turbine at steady-state conditions for two rotor configurations with similar power outputs: 1) a conventional upwind rotor with three blades and 2) a downwind pre-aligned rotor with two blades. The rotor mass was reduced by approximately 25% for the downwind pre-aligned configuration. In addition, the damage equivalent loads on the blades were reduced more than 60% for the downwind pre-aligned configuration. However, additional work is needed to investigate this concept at turbulent inflow conditions and for extreme events.
- Mineral Surface Catalyzed Polymerization Of Estrogen And Microbial Deactivation By Fe3+-Saturated Montmorillonite: A Potentially Low Cost Material For Water DecontaminationQin, Chao (Virginia Tech, 2017-02-07)With advantages of high cation exchange capacity, swelling-shrinking property and large specific surface area, monmtorillonite is chosen as a carrier and modified with Fe3+ saturation for estrogen decontamination. 17β-Estradiol (βE2) has highest estrogenic activity among estrogens and is selected as representative compound. Rapid βE2 transformation in the presence of Fe3+ - saturated montmorillonite in aqueous system was observed and βE2 oligomers were the major βE2 transformation products. About 98% of βE2 were transformed into oligomers which are >107 times less water-soluble than βE2 and therefore are much less bioavailable and mobile. Fe3+ -saturated montmorillonite catalysis achieved highest βE2 removal efficiency at neutral solution pH and higher temperature. Common cations did not have impact on the reaction efficiency. Dissolved organic matter slightly reduced βE2 removal efficiency. Regardless of wastewater source, ~40% βE2 removal efficiency was achieved for wastewater effluents when they were exposed to same dosage of Fe3+ -saturated montmorillonite as that for simple water systems which achieved ~83% removal efficiency. For real wastewater that contained higher organic matter, higher dosage of Fe3+ -saturated montmorillonite would be needed to create available reaction sites for βE2. This thesis also reports that Fe3+ -saturated montmorillonite effectively deactivate wastewater microorganisms. Microbial deactivation rate was 92±0.6% when secondary wastewater effluent was mixed with Fe3+ -saturated montmorillonite at 35 mg/mL for 30 min, and further increased to 97±0.6% after 4-h exposure. Freeze-drying Fe3+ -saturated montmorillonite iii after each usage resulted in 82±0.5% microbial deactivation efficiency even after fourth consecutive use. For convenient application, Fe3+ -saturated montmorillonite was further impregnated into filter paper through wet-end addition and formed uniformly impregnated paper. Scanning electron microscopy (SEM) imaging showed Fe3+ -saturated montmorillonite was evenly dispersed over cellulose fiber surface. When filtering 50 mL and 200 mL water spiked with live Escherichia coli (E. coli) cells at 3.67×108 CFU/mL, Fe3+ -saturated montmorillonite impregnated paper with 50% mineral weight loading deactivated E. coli with 99% and 77%, respectively. Dielectrophoresis and impedance analysis of filtrate confirmed that the deactivated E. coli passing through Fe3+ -saturated montmorillonite paper did not have trapping response due to higher membrane permeability and conductivity. The results demonstrate feasibility of using Fe3+ -saturated montmorillonite impregnated paper for convenient point-of-use drinking water disinfection.