Study of modified Westergaard formula based on dynamic model test on shaking table

Mingming Wang,Yi Yang,Weirong Xiao 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.5

The dynamic model test of dam-reservoir coupling system for a 203m high gravity dam is performed to investigate effects of reservoir water on dynamic responses of dam during earthquake. The hydrodynamic pressure under condition of full reservoir, natural frequencies and acceleration amplification factors along the dam height under conditions of full and empty reservoir are obtained from the test. The results indicate that the reservoir water have a stronger influence on the dynamic responses of dam. The measured natural frequency of the dam model under full reservoir is 21.7% lower than that of empty reservoir, and the acceleration amplification factor at dam crest under full reservoir is 18% larger than that under empty reservoir. Seismic dynamic analysis of the gravity dams with five different heights is performed with the Fluid-Structure Coupling Model (FSCM). The hydrodynamic pressures from Westergaard formula are overestimated in the lower part of the dam body and underestimated in its upper part to compare with those from the FSCM. The underestimation and overestimation are more significance with the increase of the dam height. The position of the maximum hydrodynamic pressure from the FSCM is raised with the increase of dam height. In view of the above, the Westergaard formula is modified with consideration in the influence of the height of dam, the elasticity of dam on the hydrodynamic pressure. The solutions of modified Westergaard formula are quite coincident with the hydrodynamic pressures in the model test and the previous report.

Kinetics of Horseradish Peroxidase-Catalyzed Nitration of Phenol in a Biphasic System

( Mingming Kong ),( Yang Zhang ),( Qida Li Runan Dong ),( Haijun Gao ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.2

The use of peroxidase in the nitration of phenols is gaining interest as compared with traditional chemical reactions. We investigated the kinetic characteristics of phenol nitration catalyzed by horseradish peroxidase (HRP) in an aqueous-organic biphasic system using n-butanol as the organic solvent and NO₂ - and H₂O₂ as substrates. The reaction rate was mainly controlled by the reaction kinetics in the aqueous phase when appropriate agitation was used to enhance mass transfer in the biphasic system. The initial velocity of the reaction increased with increasing HRP concentration. Additionally, an increase in the substrate concentrations of phenol (0-2 mM in organic phase) or H₂O₂ (0-0.1 mM in aqueous phase) enhanced the nitration efficiency catalyzed by HRP. In contrast, high concentrations of organic solvent decreased the kinetic parameter V_max/K_m. No inhibition of enzyme activity was observed when the concentrations of phenol and H₂O₂ were at or below 10 mM and 0.1 mM, respectively. On the basis of the peroxidase catalytic mechanism, a double-substrate ping-pong kinetic model was established. The kinetic parameters were K_m ^H2O2 = 1.09 mM, K_m ^PhOH = 9.45 mM, and V_max = 0.196 mM/min. The proposed model was well fit to the data obtained from additional independent experiments under the suggested optimal synthesis conditions. The kinetic model developed in this paper lays a foundation for further comprehensive study of enzymatic nitration kinetics.

Expression and evolution of the phospholipase C gene family in Brachypodium distachyon

Xianguo Wang,Yang Liu,Zheng Li,Xiang Gao,Jian Dong,Mingming Yang 한국유전학회 2020 Genes & Genomics Vol.42 No.9

Background Phospholipase C (PLC) is an enzyme that hydrolyzes phospholipids and plays an important role in plant growth and development. The Brachypodium distachyon is a model plant of Gramineae, but the research on PLC gene family of Brachypodium has not been reported. Objective This study was performed to identify the PLC family gene in Brachypodium and to determine the expression profles of PLCs under the abiotic stress. Methods Complete genome sequences and transcriptomes of Brachypodium were downloaded from the PLAZA. The hidden Markov model-based profle of the conserved PLC domain was submitted as a query to identify all potential PLC domain sequences with HMMER software. Expression profles of BdPLCs were obtained based on the qRT-PCR analysis. Results There were 8 PLC genes in Brachypodium (BdPI-PLCs 1–4 and BdNPCs 1–4). All members of BdPI-PLC had three conserved domains of X, Y, and C2, and no EF-hand was found. All BdNPCs contained a phosphatase domain. BdPIPLC genes were distributed on Chr1, Chr2 and Chr4, with diferent types and numbers of cis-regulatory elements in their respective gene promoters. Phylogenetic analysis showed that the genetic relationship between Brachypodium and rice was closer than Arabidopsis. The expression patterns of BdPI-PLC gene under abiotic stresses (drought, low temperature, high temperature and salt stress) were up-regulated, indicated their important roles in response to low temperature, high temperature, drought and salt stresses. Conclusions This study provides comprehensive information for the study of Brachypodium PLC gene family and lays a foundation for further research on the molecular mechanism of Brachypodium stress adaptation.

MODEL EXPERIMENTALS OF FAST-CLOSING-GATE FOR THE LAXIWA HYDROPOWER STATION

QINGSHENG CHEN,ZUHUI SHI,YU YANG,JIACAI LV,MINGMING LIU,YONGPING LIAO,JUN ZHOU 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Flame Retardancy of Epoxy Resin Improved by Graphene Hybrid Containing Phosphorous, Boron, Nitrogen and Silicon Elements

Li Li,Huan Wang,Fenglin Hua,Mingming Wang,Yuanshuo Zhang,Hui Xi,Jing Yang,Zhiwang Yang,Ziqiang Lei 한국고분자학회 2021 Macromolecular Research Vol.29 No.9

An effective ternary organic-inorganic composite flame retardant of reduced graphene oxide-poly-dopamine@graphitic carbon nitride@10-(2,5-dihydroxyphenyl)- 10-H-9-oxa-10-phosphaphenanthrene-10-oxide (RGO-PDA@g-C3N4@ODOPB) was successfully fabricated by co-precipitation method. Its property concerning the intrinsic flame retardancy and the mechanical performance was well studied when it was used as co-additives in combination with ammonium polyphosphate (APP) in epoxy resin (EP) samples. The surface morphology and the structure of RGO-PDA@g-C3N4 @ODOPB were characterized by SEM, and the molecular structure and compositions were investigated by FT-IR, powder XRD and 1H NMR. TGA, limit oxygen index (LOI), vertical burning test (UL-94), cone calorimeter test, and SEM were also used to investigate the thermal properties and flame retardancy of materials. As expected, the flame retardancy of EP was significantly heightened after adding of RGOPDA@ g-C3N4@ODOPB composites. It showed that with the 20% adding of RGO-PDA@g-C3N4@ODOPB/APP into EP led to the decreasing of the peak heat release rate and the total heat release at 78% and 62.5%, respectively. Meanwhile, the LOI value of the EP composites was as high as 29% and reached UL-94 V-0 rate. It was deemed that the excellent flame retardancy was attributed to the forming of compact and stable carbon layer, which was being catalytic carbonization by APP existed in the RGO-PDA@g-C3N4@ODOPB/APP composites. At the same time, the non-combustible gas released from thermal cracking of g-C3N4 during the combustion also benefited the flame retardant performance of EP.

Performance of Ca-Based Oxygen Carriers Decorated by K₂CO₃ or Fe₂O₃ for Coal Chemical Looping Combustion

Guo, Qingjie,Liu, Yongzhuo,Jia, Weihua,Yang, Mingming,Hu, Xiude,Ryu, Ho-Jung American Chemical Society 2014 ENERGY AND FUELS Vol.28 No.11

<P>Chemical looping combustion (CLC) of coal is an attractive technology with inherent CO<SUB>2</SUB> separation and high energy utilization efficiency. The large-scale preparation of a cheap oxygen carrier with high attrition resistance challenges the scale-up step of CLC reactor systems. To improve the reactivity between the CaSO<SUB>4</SUB>/bentonite (CaBen) oxygen carrier and coal, CaSO<SUB>4</SUB>–Fe<SUB>2</SUB>O<SUB>3</SUB>/bentonite (CaFeBen) and CaSO<SUB>4</SUB>–K<SUB>2</SUB>CO<SUB>3</SUB>/bentonite (CaKBen), decorated by Fe<SUB>2</SUB>O<SUB>3</SUB> and K<SUB>2</SUB>CO<SUB>3</SUB>, respectively, were prepared in this work. The active component content, multi-cycle reactivity, and enhancement mechanism of two decorated oxygen carriers were investigated in a fluidized bed with steam as the gasification–fluidization medium. Finally, three types of coals, including lignite, bitumite, and anthracite, were used as fuel. The addition of Fe<SUB>2</SUB>O<SUB>3</SUB> and K<SUB>2</SUB>CO<SUB>3</SUB> can improve the reactivity of the CaBen oxygen carrier but degrade the attrition resistance slightly. The multiple-cycle experiments indicated that Fe<SUB>2</SUB>O<SUB>3</SUB> itself is the oxygen carrier for coal CLC with high reactivity, while K<SUB>2</SUB>CO<SUB>3</SUB> acts as the catalysis for coal gasification. The carbon conversion rate of the three coals that reacted with the CaKBen oxygen carrier was higher than that with CaFeBen as the oxygen carrier because of catalysis of potassium on the coal gasification reaction. However, the CaKBen oxygen carrier particles were seriously sintered, and the potassium content in the oxygen carrier reduced with the increasing redox cycles. The coals with high volatile and ash contents have a high instantaneous rate of carbon conversion reacted with two decorated oxygen carriers.</P>

‘‘Anode-free” Zn/LiFePO4 aqueous batteries boosted by hybrid electrolyte

Jingying Duan,Luofu Min,Mengqian Wu,Ting Yang,Mingming Chen,Chengyang Wang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Aqueous rechargeable batteries with Zn as anode directly have become prospective alternatives to conventionallithium-ion batteries. However, the growth of zinc dendrites restricts the practical applicationof Zn anode greatly. In addition, the use of thick zinc foil as anode also increases the total weight of thebattery and impacts the whole energy density. Herein, a kind of ‘‘anode-free” Zn/LiFePO4 battery (zeroexcessZn) is designed to solve such problems, and corresponding electrolyte is optimized to ensurethe electrochemical performance. As a result, ethylene glycol (EG) is added to the aqueous electrolytewith 1.5 M Zn(CF3SO3)2 and 1.5 M LiCF3SO3 as solutes, which not only improves the stability of the electrolyte,but also inhibits the growth of zinc dendrites. And the Zn/Cu batteries with 70 vol% EG/H2Ohybrid electrolyte show highly reversible Zn plating/stripping process, in which the average coulombicefficiency (ACE) is as high as 99.77 % at a current density of 1 mA cm2. In order to better adapt to the‘‘anode-free” Zn/LiFePO4 battery system, the ratio of Zn2+ to Li+ ions in this electrolyte is further optimized,and it’s found that the battery with 2 M Zn(CF3SO3)2 + 1 M LiCF3SO3-70 vol% EG/H2O electrolyteshows the most excellent electrochemical stability, in which the capacity retention rate is 75.2 % after100 cycles at a current density of 1 mA cm2. Our work makes it possible for the application of aqueous‘‘anode-free” batteries.

Topology and start-up strategy for DC-DC transformers based on voltage balancing unit

Zhang, Jialin,Zha, Kunpeng,Tang, Xiaojun,Yang, Yuefeng,Yan, Hui,Wen, Fuyue,Shi, Mingming The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.7

As a core piece of equipment in DC distribution networks, DC solid-state transformers (DCSSTs) are attracting more and more attention in academia and industry. Due to the limitations in terms of the electrical stress of the switches, the input series output parallel (ISOP) structure is adopted in DCSSTs. This paper proposed an improved DCSST topology based on a voltage balancing unit (VBU). This topology has the advantages of higher power density, reduced weight, and cascaded number without compromising efficiency, cost, or reliability. The working modes, mathematical models, and control strategy are analyzed. In addition, a start-up strategy and a parameter design method are proposed in this paper. Simulation and experimental results verify the correctness and effectiveness of the proposed solution. The proposed DCSST is a practical scheme for the application of DC distribution networks.

A mechanical metamaterial made from a DNA hydrogel.

Lee, Jong Bum,Peng, Songming,Yang, Dayong,Roh, Young Hoon,Funabashi, Hisakage,Park, Nokyoung,Rice, Edward J,Chen, Liwei,Long, Rong,Wu, Mingming,Luo, Dan Nature Pub. Group 2012 Nature nanotechnology Vol.7 No.12

<P>Metamaterials are artificial substances that are structurally engineered to have properties not typically found in nature. To date, almost all metamaterials have been made from inorganic materials such as silicon and copper, which have unusual electromagnetic or acoustic properties that allow them to be used, for example, as invisible cloaks, superlenses or super absorbers for sound. Here, we show that metamaterials with unusual mechanical properties can be prepared using DNA as a building block. We used a polymerase enzyme to elongate DNA chains and weave them non-covalently into a hydrogel. The resulting material, which we term a meta-hydrogel, has liquid-like properties when taken out of water and solid-like properties when in water. Moreover, upon the addition of water, and after complete deformation, the hydrogel can be made to return to its original shape. The meta-hydrogel has a hierarchical internal structure and, as an example of its potential applications, we use it to create an electric circuit that uses water as a switch.</P>

Phosphoinositide‑specific phospholipase C gene involved in heat and drought tolerance in wheat (Triticum aestivum L.)

Wang Xianguo,Yao Xiaolu,Zhao Ahui,Yang Mingming,Zhao Wanchun,LeTourneau Melissa K.,Dong Jian,Gao Xiang 한국유전학회 2021 Genes & Genomics Vol.43 No.10

Background Phosphoinositide-specifc phospholipase C proteins mediate environmental stress responses in many plants. However, the potential of PI-PLC genes involved with abiotic stress tolerance in wheat remains un-explored. Objective To study TaPLC1 genetic relation with wheat drought and heat resistance. Methods The seedlings were treated with PI-PLC inhibitor U73122 at the single leaf stage. The seedlings were treated with drought and heat stress at the two leaf stage, and some physiological indexes and the expression profle of TaPLC1 gene were determined. And the TaPLC1 overexpression vector was transferred to Arabidopsis and selected to T3 generation for drought and heat stress treatment. Results After 4 h of drought and heat stress, the SOD activity, MDA and soluble sugar content of the two cultivars with inhibitor were higher than those without inhibitor, the chlorophyll content decreased. CS seedlings showed signifcant wilting phenomenon, and TAM107 showed slight wilting. After the elimination of drought and heat stress, all seedling wilting gradually recovered, while the leaf tips of the two varieties treated with inhibitors began to wilt and turn yellow, which was more signifcant 5 days after the drought and heat stress, while the degree of spring wilting and yellow in CS was earlier than that in TAM107. The expression patterns of TaPLC1 gene were diferent in the two cultivars, but the expression levels reached the maximum at 30 min of heat stress. The change of TaPLC1 expression in TAM107 without inhibitor treatment was signifcantly greater than that in CS. The expression level of TaPLC1 in the two cultivars under stress was signifcantly diferent between the two cultivars treated with inhibitor and untreated, and was lower than that of the normal plants under normal conditions. These results indicated that inhibition of TaPLC1 gene expression could enhance the sensitivity of seedlings to stress. In Arabidopsis, the root lengths of transgenic and wild-type seedlings were shortened after drought stress treatment, but the root lengths of transgenic plants decreased slightly. And the expression of TaPLC1 gene was signifcantly increased after drought and heat stress. This indicated that overexpression of TaPLC1 improved drought resistance of Arabidopsis. Conclusions The results of this study suggest that TaPLC1 may be involved in the regulation mechanism of drought and heat stress in wheat.