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( Shuang Xiu Wu ),( Liang He ),( Rong Rong Shen ),( Xiu Zhang ),( Quan Xi Wang ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.8
A genomic DNA fragment encoding a putative maltooligosyltrehalose trehalohydrolase (NfMTH) for trehalose biosynthesis was cloned by the degenerate primer-PCR from cyanobacterium Nostoc flagelliforme. The ORF of NfMTH is 1,848 bp in length and encodes 615 amino acid residues, constituting a 70 kDa protein. The deduced amino acid sequence of NfMTH contains 4 regions highly conserved for MTHs. By expression of NfMTH in E. coli, the function of this protein was demonstrated, where the recombinant protein catalyzed the hydrolysis of maltooligosyl trehalose to trehalose. The expressions of MTH and maltooligosyltrehalose synthase in the filaments of N. flagelliforme were upregulated significantly under dehydration stress, NaCl stress, and high temperature-drought stress. The accumulations of both trehalose and sucrose in the filaments of N. flagelliforme were also improved significantly under the above stresses. Furthermore, trehalose accumulated in smaller quantities than sucrose did when under NaCl stress, but accumulated in higher quantities than sucrose did when under temperature-drought stress, indicating that both trehalose and sucrose were involved in N. flagelliforme adapted to stresses and different strategies conducted in response to various stress conditions.
Shuang-Ying Wu,Ying-Ying Wu,Lan Xiao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8
The effect of thermal radiation on convection heat transfer in flat-box type cooling channel of photovoltaic thermal system with tilt angleof 30 degree was studied by 3D numerical simulation under constant heat flux boundary condition. The temperature contours andvelocity fields of fluid near the outlet were obtained. The variations of wall temperature and convection Nusselt number along flow directionfor all the separate walls composing the cooling channel were compared and analyzed. The results show that due to thermal radiation,the deflection of the maximum velocity region to heated top wall, together with the asymmetry of temperature field is weakened. Fornatural convection, radiation promotes the formation of multi-vortices. For mixed convection, heat transfer on all the cooling channelwalls is enhanced under the condition of lower heat flux while heat transfer on heated top wall is deteriorated when the heat flux is relativehigh. Also, pressure re-rising is promoted by thermal radiation.
Parametric study on flow and heat transfer characteristics of porous wick evaporator based on AMTEC
Shuang-Ying Wu,Bao-Xi Cao,Lan Xiao,You-Rong Li 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3
By establishing an axial symmetric invariable temperature phase change interface model of porous wick evaporator based on alkali metal thermal-to-electric converter (AMTEC), a parametric study has been implemented to explore the impact of effective thermal conductivity model, working fluid, wick material, porosity and particle size of porous wick on the flow and heat transfer characteristics. The results indicate that the inner surface temperature profile of wick is closely dependent on effective thermal conductivity models; it is the minimum for series model while the highest for parallel model. The inner surface temperature of wick with Na-K alloy as working fluid is obviously lower than that with sodium or potassium as working fluid. The wick made of refractory ceramics makes the minimum of inner surface temperature, while the one with nickel appears the highest temperature. Increasing the porosity can reduce the pressure drop in the wick, but also increases the temperature of evaporator.
Shuang-Ying Wu,Su-Jun Chen,Lan Xiao,You-Rong Li 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.6
In this study, numerical investigations are conducted for forced convective heat transfer in an annular helicoidal tube under uniform wall temperature condition for laminar flow including developing region. The numerical computations reveal the developments and distributions of heat transfer and flow fields in the annular helicoidal tube when the outer tube wall is heated and the inner tube wall is insulated. The effects of Reynolds number, curvature ratio, and coil pitch on the circumferential average friction factor and Nusselt number at different axial locations, and the non-dimensional entropy generation number of laminar convection in an annular helicoidal tube are investigated. In addition, the differences of flow and heat transfer characteristics between the annular helicoidal tube and circular helicoidal tube are also described.
Investigation of muscle-specific beef color stability at different ultimate pHs
Wu Shuang,Han Jina,Liang Rongrong,Dong Pengcheng,Zhu Lixian,Hopkins David L.,Zhang Yimin,Luo Xin 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.12
Objective: This study was aimed to investigate the muscle-specific beef color stability at normal and high ultimate pHs. Methods: The impact of muscle (Longissimus lumborum [LL] vs psoas major [PM]) and pH (normal ultimate pH [Np] vs high pH dark cutting beef [Hp]) on color stability, indicated by basic color traits, metmyoglobin reducing activity (MRA) and oxygen consumption (OC), as well as the lipid oxidation, were determined over 7 days of display at 4°C. Results: Hp-LL had the highest pH (6.92), followed by Hp-PM (6.01), Np-PM (5.76), and Np-LL (5.52). Hp-LL had increased (p<0.05) a*, chroma and % oxymyoglobin during display. Hp-LL also had the highest metmyoglobin (MMb) reducing activity and OC among all the samples, thus, the greatest color stability, although very dark throughout storage, with lowest values for lightness (L*) and yellowness (b*). Np-LL also exhibited relatively high color stability, as a result of its lower % MMb and OC and higher MRA than psoas muscle samples. The 0.2 unit difference of the pH between Hp and Np psoas muscle, resulted in the difference of the color intensity, not the color stability. Interestingly, high pH psoas muscle (Hp-PM) did not have better color stability than Np-PM, and in fact had lower color stability than even Np-LL. The similar level of OC and lipid oxidation cannot explain the difference in color stability between Hp-PM and Np-LL. Conclusion: The Hp does not always show better color stability compared with Np beef, which depends on the muscle type. The balance of MRA and OC is important to keep the color in great intensity and stability in the meantime.
Shuang-Ying Wu,Chun Li,Lan Xiao,You-Rong Li,Chao Liu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12
This paper gives a special focus on the role of outlet temperature of flue gas (Tgo) in organic Rankine cycle (ORC) system for low temperatureflue gas waste heat recovery. The variations of performance indicators: net work (Wnet), exergy efficiency (ηex) and levelizedenergy cost (LEC) versus Tgo are discussed. Considering the corrosion of low temperature flue gas, the necessity and reasonability oflimiting Tgo at its minimum allowed discharge temperature (355.15 K) are analyzed. Results show that there exist optimal Tgo (Tgo,opt) forWnet and LEC, while Tgo,opt for ηex does not appear under the investigated range of Tgo. Moreover, the Tgo,opt for Wnet is always lower than355.15 K, the Tgo,opt for LEC, despite being greater than the one for Wnet, is just slightly higher than 355.15 K when the inlet temperatureof flue gas varies from 408.15 K to 463.15 K. For the waste heat recovery of low temperature flue gas, it is reasonable to fix Tgo at 355.15K if Wnet or LEC is selected as primary performance indicator under the pinch point temperature difference of evaporator (ΔTe) below 20K.
Exergo-economic analysis of finned tube for waste heat recovery including phase change heat transfer
Shuang-Ying Wu,Jing-Rui Jiu,Lan Xiao,You-Rong Li,Chao Liu,Jin-Liang Xu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.11
In this paper, an exergo-economic criterion, i.e. the net profit per unit transferred heat load, is established from the perspective of exergy recovery to evaluate the performance of finned tube used in waste heat recovery. Also, the dimensionless exergy change number is introduced to investigate the effect of the flow (mechanical) exergy loss rate on the recovered thermal exergy. Selecting R245fa as a working fluid and exhaust flue gas as a heat source, the effects of the internal Reynolds number Rei, the external Reynolds number Reo, the unit cost of thermal exergy εq, the geometric parameter of finned tube ηoβ and the phase change temperature Tv etc. on the performance of finned tube are discussed in detail. The results show that the higher Tv and ηoβ, and lower Rei may lead to the negligible flow (mechanical) exergy loss rate. There exists an optimal value of Rei where the net profit per unit transferred heat load peaks, while the variations of Reo, εq and Tv cause monotonic change of the net profit per unit transferred heat load. The phase change temperature exerts relatively greater influence on the exergo-economic performance of finned tube in comparison with other parameters. And there exists a critical phase change temperature, where the net profit per unit transferred heat load is equal to zero.