Study on the mixing performance of mixing vane grids and mixing coefficient by CFD and subchannel analysis code in a 5×5 rod bundle

Han Bin,Zhu Xiaoliang,Yang Bao-Wen,Liu Aiguo,Xi Yanyan,Liu Lei,Liu Shenghui,Huang Junlin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10

Mixing Vane Grid (MVG) is one of the most important structures in fuel assembly due to its high performance in mixing the coolant and ultimately increasing Critical Heat Flux (CHF), which avoids the temperature rising suddenly of fuel rods. To evaluate the mixing performance of the MVG, a Total Diffusion Coefficient (TDC) mixing coefficient is defined in the subchannel analysis code. Conventionally, the TDC of the spacer grid is obtained from the combination of experiments and subchannel analysis. However, the processing of obtaining and determine a reasonable TDC is much challenging, it is affected by boundary conditions and MVG geometries. In is difficult to perform all the large and costing rod bundle tests. In this paper, the CFD method was applied in TDC analysis. A typical 5 5 MVG was simulated and validated to estimate the mixing performance of the MVG. The subchannel code was used to calculate the TDC. Firstly, the CFD method was validated from the aspect of pressure drop and lateral temperature distribution in the subchannels. Then the effect of boundary conditions including the inlet temperature, inlet velocities, heat flux ratio between hot and cold rods and the arrangement of hot and cold rods on MVG mixing and TDC were studied. The geometric effects on mixing are also carried out in this paper. The effect of vane pattern on mixing was investigated to determine which one is the best to represent the grid's mixing performance.

Effect of Nicotinamide on Proliferation, Differentiation, and Energy Metabolism in Bovine Preadipocytes

Liu, Xiaomu,Fu, Jinlian,Song, Enliang,Zang, Kun,Wan, Fachun,Wu, Naike,Wang, Aiguo Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.9

This study examined the effects of nicotinamide on proliferation, differentiation, and energy metabolism in a primary culture of bovine adipocytes. After treatment of cells with 100-500 $\mu{M}$ nicotinamide, cell growth was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and cellular lipid content was assessed by Oil Red O staining and a triglyceride (TG) assay. Several factors related to energy metabolism, namely adenosine triphosphatase (ATPase) activity, nitric oxide (NO) content, nitric oxide synthase (NOS) activity, the number of mitochondria and the relative expression of glyceraldehydes-3-phosphate dehydrogenase (GAPDH), peroxisome proliferator-activated receptor-$\gamma$ ($PPAR_{\gamma}$) and inducible NOS (iNOS), were also investigated. Results showed that nicotinamide induced both proliferation and differentiation in bovine preadipocytes. Nicotinamide decreased NO production by inhibiting NOS activity and iNOS mRNA expression, and controlled lipolytic activity by increasing ATPase activity and the number of mitochondria. The present study provides further evidence of the effects of nicotinamide on lipid and energy metabolism, and suggests that nicotinamide may play an important role in the development of bovine adipose tissue in vivo. This emphasizes the importance of investigating bovine adipose tissue to improve our understanding of dairy cow physiology.

SO₂감지를 위한 NASICON 고체전해질 가스센서의 제조 및 특성 평가

배재철,Liu, aiguo,이상태,전희권,방영일,이덕동,허증수 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

Acidic treatment of sodium sulfide by-product sediment to recover sodium oxide and preparation porous ceramics for building applications

Changrong Liu,Hongbin Tan,Aiguo Zheng,Xiangmei Kang,Ao Jiang,Rui Fang,Haorong Ren,Wanwei Fang 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.3

The manufacture of sodium sulfide through a carbon reduction process, using sodium sulfate as raw material, generatessodium sulfide by-product sediment, which has potential health and environmental impacts. Herein, a novel strategy isproposed to recover sodium oxide from the sediment by using acidic treatment and the influence of solution pH on sodiumoxide content is systematically studied. The results reveal that the sodium oxide content decreases with decreasing pH valueof the solution. At pH = 4, the as-treated sediment results in Na2O content of 3.10 wt. %, which recovery rate is about 90%. Furthermore, the influences of sintering temperature and time on compressive strength and bulk density are studied. Ingeneral, the compressive strength and bulk density increase with increasing sintering temperature and time. After sinteringat 1,300 oC for 120 min, the compressive strength and bulk density of the sintered porous ceramic are 26.66 MPa and 1.31 g/cm3, respectively. The porous ceramic, sintered at 1,300 oC, mainly consists of hauyne, gehlenite and hematite phases. Insummary, the few flaws in cell-walls result in high compressive strength of the as-prepared porous ceramics.

Methanol sensor based on Polypyrrole-Poly (vinyl alcohol) composite prepared by chemical vaporization method

Jiang, Linshu,Liu, Aiguo,Roh, Jin-gyu,Huh, Jeung-Soo,Lee, Duk-Dong,Jun, Hee-Kwon,Lee, Sang-Tae 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

Synthesis and Gas Adsorption Properties of Carbide-Derived Carbons from Titanium Tin Carbide

Yuanyuan Zhu,Aiguo Zhou,Jin Jia,Junjun Wang,Jiang Liu,Baolin Xing,Chuanxiang Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.4

Here we reported the synthesis of nanoporous carbide-derived carbons (CDCs) from a new precursor, titanium tin carbides (Ti2SnC), via chlorination at 400–1100℃. At low chlorination temperature (400–500℃), as-synthesized CDCs mainly consisted of amorphous carbon and chlorides. As the chlorination temperature increased up to 600℃, chlorides disappeared, and the main composition of CDCs was amorphous carbon. At high chlorination temperature, there was a trend of graphitization. The microstructure of CDCs was observed and characterized by scanning electron microscopy and transmission electron microscopy. Some graphite-like sheet structures in CDCs were found. Specific surface area (SSA) and pore volume of CDCs increased with chlorination temperature, except an abnormal decrease of the CDC chlorinated at 900℃. CDC chlorinated at 1100℃ had the largest SSA, 1580 m2 /g. In order to apply these materials as novel hydrogen/methane storage media in the area of energy efficient transport, gas adsorption properties of CDCs were measured. For CDC chlorinated at 1100℃, pore volume uptakes are 206 cm3 /g at 60 bar (25℃) for methane, and ~442 cm3 /g at 35 bar (-196℃) for hydrogen, respectively. It was suggested that CDCs from Ti2SnC are promising materials for hydrogen/ methane adsorptive storage.

Novel Hierarchical TiO2/C Nanocomposite with Enhanced Photocatalytic Performance

Yupeng Gao,Hao Chen,Aiguo Zhou,Zhengyang Li,Fanfan Liu,Qianku Hu,Libo Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.5

"Hierarchical TiO2 /carbon nanocomposites were synthesized by oxidation of two-dimensional(2D) Ti3C2 nanosheets at different temperatures. Crystal structures and morphologies of the obtained samples were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy. The results show that 2D Ti3C2 nanosheets are partially oxidized to form a novel hierarchical nanostructure which is composed of carbon nanosheets and TiO2 nanoparticles. With the calcination temperature increasing, the crystal structure of TiO2 nanoparticles changes from anatase to rutile and the hierarchical structure was gradually destroyed. The photodegradation results reveal that the samples obtained at 200℃ and 285℃ show much better photocatalytic properties than P25. And meanwhile the photocatalytic property will become worse with the increase in calcinations temperature."

Effect of Channel Interaction and Presentation Level on Speech Recognitionin Simulated Bilateral Cochlear Implants

Yang-soo Yoon,Aiguo Liu,You-Ree Shin,Jae-sook Gho,Candace Hicks,Qian-Jie Fu,Allison Coltisor 한국언어재활사협회 2016 Clinical Archives of Communication Disorders Vol.1 No.1

Purpose: The present study used the acoustic simulation of bilateral cochlear implants to investigate the effect of presentation level (EXP 1) and channel interaction (EXP 2) on binaural summation benefit in speech recognition. Methods: The acoustic 6-channel processors were constructed, and the envelope of each band was used to modulate a sinusoid (EXP 1) or band-pass filtered white noise (EXP 2) with a frequency matching the center frequency of the carrier band. Presentation level was fixed for one ear and varied for the other. Channel interaction was simulated by altering filter slopes while keeping interaural spectral peaks matched in the carrier bands. Two separate groups of ten adult subjects with normal hearing participated in EXP 1 and EXP 2. Sentence recognition was measured with left ear alone, right ear alone, and both ears in quiet and in noise at +5 dB signal-to-noise ratio. Results: A significant binaural summation benefit occurs only in noise, regardless of interaural mismatch in channel interactions and presentation levels. Conclusions: Results suggest that factors other than channel interaction are important and that matching interaural loudness is an unimportant factor in binaural summation benefit in noise. For both EXP 1 and EXP 2, the data trend is indicative of speech information perceived in quiet being fully coded by the better performing ear alone, which leads to no binaural summation benefit. The results of current and future studies could have implications in programming of bilateral cochlear implant users.

Development of EST-SSRs from the ark shell (Scapharca broughtonii) transcriptome and their application in genetic analysis of four populations

Wenjing Wang,Biao Wu,Zhihong Liu,Liqing Zhou,Xiujun Sun,Jiteng Tian,Aiguo Yang 한국유전학회 2021 Genes & Genomics Vol.43 No.6

Background The ark shell (Scapharca broughtonii) is one of the most economically important mollusks in the Bohai Sea and Yellow Sea of China. In recent years, ark shells from the Korean population were introduced to China for seed propagation and culture. Objective To explore the impact of the introduction of Korean ark shell on the genetic diversity of native population in China. Methods Simple sequence repeat (SSR) is efective and widely used tool for genetic analysis. In this study, 180 EST-SSRs were selected and verifed by polymerase chain reaction and polyacrylamide gel electrophoresis. Subsequently, fve polymorphic EST-SSRs were screened and their primers were modifed by fuorescein for use in the genetic analysis of four populations. Results Genetic analysis showed that 361 alleles amplifed by fve SSR loci were detected in the four populations. The number of alleles for the fve SSRs ranged from 8 to 30, with a mean of 18.05 (standard deviation, SD=6.492). The efective number of alleles varied from 2.253 to 22.222, with a mean of 10.596 (SD=4.713). Observed heterozygosity and expected heterozygosity were 0.167–0.833 and 0.566–0.971, with average values of 0.520 (SD=0.177) and 0.891 (SD =0.062), respectively. Polymorphic information content ranged from 0.521 to 0.953, with a mean of 0.865 (SD=0.070). The pairwise genetic diferentiation coefcient (FST) of the four populations ranged from 0.0267 to 0.0477, showing low genetic diferentiation. The phylogenetic tree constructed by neighbor-joining method showed that the genetic distance between the Chinese Dalian native population and three Korean populations was relatively more far than that among those Korean populations. Conclusion The results indicated that the genetic structure of the Dalian wild population was less afected by the introduced Korean wild populations.

Structural Characterization of Microwave-Assisted Solution-Synthesized Strontium-Substituted Hydroxyapatite

Jianguo Liao,Yanqun Li,Xiali Guan,Jingxian Liu,Yongxiang Zhang,Yufen Xie,Zhengpeng Yang,Xingze Duan,Aiguo Zhou,Jiangnan Zhu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.10

Hydroxyapatite and strontium-substituted hydroxyapatite nanoparticles (n-HA and Sr-HA) were prepared by microwave-assisted solution synthesis with aqueous solutions of various Sr/(Sr+Ca) molar ratios ranging from 0% to 15%. The structural properties of the hydroxyapatite powders were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy and Raman spectra, field emission scanning electron microscopy coupled with energy dispersive X-ray spectrometry and transmission electron microscopy. The results confirmed that strontium ions had been incorporated into the hydroxyapatite lattice. The synthetic n-HA and Sr-HA nanocrystalline consisted of hydroxyapatite crystalline phase with hexagonal structure, and the particle size was 30–40 x 60–70 nm and 40–50 x 70–80 nm, respectively. The calcined HA particle size ranged from about 120 nm to 150 nm, the calcined Sr-HA products were composed of spherical aggregates with a size of about 70–100 nm. The incorporation of Sr ions lead to the formation of vacancies in the crystal structure of the HA. The results indicated that the strontium substitution did not change the crystal structures. More Sr resulted in less calcined crystallites and formed agglomerates owing to the size effect.