Sea Environmental Design Criteria for Coastal and Offshore Structures

Defu Liu 한국해안해양공학회 1996 학술강연회 발표논문초록집 Vol.1 No.1

Extreme sea statistics and combinations of environmental events or response for structures are very important problem in performance cvaluation and design of coastal and Offshore structures. A probabilistic method is developed that leads to the combination of Typhoon (hurricane) or winter storm induces winds, waves, currents and surge for a generic site. The traditional recommendation for the fixed structures is a combination of the 100 years maximum wave height with the 100 years wind and current. This approach is, however, unduly conservative, since the largest wind, wave and current values in 100 years are not experted to occur at precisely the same time. Previous studies of combinations of extreme sea environmental conditions fall into two categories: first, the generic load model defines a surface in the multivariate space of meteorologicaloceanic variables, such as the joint probability of waves, currents, winds and storm surge: second, use the structural response to combine the environmental variables, such as overturning moment (OTM), base shear forces and etc. [1-4]. While the great majority of publications are concentrated in combinations of responses, although 100 years response is not corresponding to wave, wind and current with 100 years joint probability. Since the combination design criteria is considered with extreme statistics of individual environmental events and their joint probability,in this paper some new concept for mentioned above problems is proposed.

Combination Sea Environmental Design Criteria for Marine Structures

Defu, Liu 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11

Extreme sea statistics and combinations of extreme events or response for structures are very important problem in performance evaluation and design of coastal and Offshore structures. A probabilistic method is developed that leads to the combination of Typhoon(Hurricane) or winter storm induces winds, waves, currents and surge for generic site. The traditional recommendation for the fixed structures in a combination of the 100years maximum wave height with the 100 years wind and current. This approach is, however, unduly conservative, since the largest wind, wave and current values in 100years are not expected to occur at precisely the same time. Previous studies of combinations of extreme sea environmental conditions fall into two catagories : first, the generic load model defines a surface in the multivariate space of meteorological-oceanic variables, such as the joint probability of waves, currents winds and storm surges; second use the structural response to combine the environmental variables, such as overturning moment(OTM), base shear fores and etc.. While the great majority of publications are concentrated in combinations of responses, although 100 years response is not corresponding to wave, wind and current with 100 years joint probability. Since the combination design criteria is considered with extreme statistics of individual environmental events and their joint probability, in this paper some new concept for mentioned above problems is proposed.

Cloning and Functional Characterization of Putative Escherichia coli ABC Multidrug Efflux Transporter YddA

( Zhenyue Feng ),( Defu Liu ),( Ziwen Liu ),( Yimin Liang ),( Yanhong Wang ),( Qingpeng Liu ),( Zhenhua Liu ),( Zhongjing Zang ),( Yudong Cui ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7

A putative multidrug efflux gene, yddA, was cloned from the Escherichia coli K-12 strain. A drugsensitive strain of E. coli missing the main multidrug efflux pump AcrB was constructed as a host and the yddA gene was knocked out in wild-type (WT) and drug-sensitive E. coliΔacrB to study the yddA function. Sensitivity to different substrates of WT E.coli, E. coliΔyddA, E. coliΔacrB and E. coliΔacrBΔyddA strains was compared with minimal inhibitory concentration (MIC) assays and fluorescence tests. MIC assay and fluorescence test results showed that YddA protein was a multidrug efflux pump that exported multiple substrates. Three inhibitors, ortho-vanadate, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and reserpine, were used in fluorescence tests. Ortho-vanadate and reserpine significantly inhibited the efflux and increased accumulation of ethidium bromide and norfloxacin, while CCCP had no significant effect on YddA-regulated efflux. The results indicated that YddA relies on energy released from ATP hydrolysis to transfer the substrates and YddA is an ABC-type multidrug exporter. Functional study of unknown ATP-binding cassette (ABC) superfamily transporters in the model organism E. coli is conducive to discovering new multidrug resistance-reversal targets and providing references for studying other ABC proteins of unknown function.

Acteoside reduces testosterone by inhibiting cAMP, p450scc, and StAR in rat Leydig cells

Shuqiang Liu,Junwen Zhang,Weixuan Li,Tianxiang Zhang,Defu Hu 대한독성 유전단백체 학회 2015 Molecular & cellular toxicology Vol.11 No.1

The present study investigated the in vivo and in vitro effects of acteoside on testosterone production in Sprague-Dawley (SD) rats. The in vivo experiment revealed that acteoside reduced the testosterone level in serum significantly (P⁄0.05). The in vitro experiment also illustrated that acteoside significantly reduced testosterone production in SD rat Leydig cells in primary culture (P⁄0.05). Enzyme-linked immunosorbent assay results demonstrated that acteoside significantly reduced the cyclic adenosine 3′, 5′-monophosphate (cAMP) level (P⁄0.05), and Western blot analysis showed that acteoside significantly reduced cholesterol side-chain cleavage enzyme (p450scc) and steroidogenic acute regulatory (StAR) expression (P⁄ 0.05). Hoechst 33342 staining and Western blotting showed that acteoside did not induce apoptosis in Leydig cells. Together, these results suggest that the acteoside-induced reduction in testosterone production in rat may be at least partially due to down-regulation of cAMP, p450scc, and StAR, but not apoptosis.

Effect of Pack Rolling and Heat Treatment on Microstructure and Mechanical Properties of B4CP/6061Al Composite Prepared by Powder Metallurgy

Shengpu Liu,Zhaoyao Zhou,Defu Li,Shengli Guo,Shi Shu 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

This study aims to investigate the effect of hot pack rolling and T6 heat treatment on microstructure and mechanical propertiesof 25 vol% B4CP/6061Al composite fabricated by powder metallurgy. Results show that hot pack rolling process couldbreak the particle agglomeration, refine grain size, decrease porosity and improve the interface bonding quality. Almost15%, 21% and 328% improvement in ultimate tensile strength, yield strength and elongation for B4CP/6061Al compositewere obtained after hot pack rolling. It was also found that the average grain size increased due to the static recrystallizationduring the T6 heat treatment process. XRD patterns revealed that Mg2Siprecipitation hardening phase was formed inthe matrix. Compared with the rolled B4CP/6061Al composite, T6 heat treatment resulted in improving the ultimate tensilestrength, yield strength and elongation by 7%, 11% and 50%. The strengthening mechanisms and fractured surfaces underdifferent stages were also discussed.

Effects of Maize Source and Complex Enzymes on Performance and Nutrient Utilization of Broilers

Tang, Defu,Hao, Shengyan,Liu, Guohua,Nian, Fang,Ru, Yingjun Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.12

The objective of this study was to investigate the effect of maize source and complex enzymes containing amylase, xylanase and protease on performance and nutrient utilization of broilers. The experiment was a $4{\times}3$ factorial design with diets containing four source maize samples (M1, M2, M3, and M4) and without or with two kinds of complex enzyme A (Axtra XAP) and B (Avizyme 1502). Nine hundred and sixty day old Arbor Acres broiler chicks were used in the trial (12 treatments with 8 replicate pens of 10 chicks). Birds fed M1 diet had better body weight gain (BWG) and lower feed/gain ratio compared with those fed M3 diet and M4 diet (p<0.05). Apparent ileal crude protein digestibility coefficient of M2 was higher than that of M3 (p<0.05). Apparent metabolisable energy (AME) and nitrogen corrected AME (AMEn) of M1 were significant higher than those of M4 (p<0.05). Supplementation of the basal diets with enzyme A or B improved the BWG by 8.6% (p<0.05) and 4.1% (p>0.05), respectively. The fresh feces output was significantly decreased by the addition of enzyme B (p<0.05). Maize source affects the nutrients digestibility and performance of broilers, and a combination of amylase, xylanase and protease is effective in improving the growth profiles of broilers fed maize-soybean-rapeseed-cotton mixed diets.

Time-Matching Poisson Multi-Bernoulli Mixture Filter For Multi-Target Tracking In Sensor Scanning Mode

Xingchen Lu,Dahai Jing,Defu Jiang,Ming Liu,Yiyue Gao,Chenyong Tian 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.6

In Bayesian multi-target tracking, the Poisson multi-Bernoulli mixture (PMBM) filter is a state-of-the-art filter based on the methodology of random finite set which is a conjugate prior composed of Poisson point process (PPP) and multi-Bernoulli mixture (MBM). In order to improve the random finite set-based filter utilized in multi-target tracking of sensor scanning, this paper introduces the Poisson multi-Bernoulli mixture filter into time-matching Bayesian filtering framework and derive a tractable and principled method, namely: the time-matching Poisson multi-Bernoulli mixture (TM-PMBM) filter. We also provide the Gaussian mixture implementation of the TM-PMBM filter for linear-Gaussian dynamic and measurement models. Subsequently, we compare the performance of the TM-PMBM filter with other RFS filters based on time-matching method with different birth models under directional continuous scanning and out-of-order discontinuous scanning. The results of simulation demonstrate that the proposed filter not only can effectively reduce the influence of sampling time diversity, but also improve the estimated accuracy of target state along with cardinality.

Some Factors Affecting Freezing of Boar Semen in 5 ml Maxi-straws

Dai, J.J.,Wu, C.F.,Zhang, Defu,Yin, F.Z.,Zhang, T.Y.,Liu, D.,Wu, H.L.,Li, L.L.,Yang, S.T.,Wang, L. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.4

A series of experiments were conducted to determine the suitable freezing and thawing temperatures for the freezing of boar semen in 5 ml maxi-straws. The ultrastructure, in vitro fertilization (IVF) and artificial insemination (AI) of frozen-thawed semen were also be evaluated. The 5 cm freezing height gave the best results not only in post-thaw motility rate (54.00%), but also in normal acrosome morphology rate (NAR) (80.23%). There was no significant difference in the post-thaw motility between different thawing temperatures and corresponding thawing times (p>0.05); the group of $52^{\circ}C$ and 25 s gave the highest motility rate (45.00%). As a whole, not only from the motility but also the NAR, thawing at $42^{\circ}C$ was better than the other two treatments. In the freezing packages, 5 ml maxi-straw gave a little lower mobility (40%), viability rate (49.58%), plasma membrane integrity rate (53.91%) and NAR (52.65%) than the 0.25 ml straw, but there was no significant difference between the two straw volumes (p>0.05). The IVF capacity of frozen-thawed semen in this experiment was similar to fresh semen. From ultrastructure observation, the main damage to boar spermatozoa after freezing was seen in the acrosome, such as swelling and formation of vesicles. After AI in recipient Shanghai White sows, frozen-thawed semen from 5 ml maxi-straws and pellets produced 72.2% and 80% conception rate and 7.8 and 8 litter sizes, respectively, and there was no significant difference between the 5 ml maxi-straw and the pellet (p>0.05).

Effect of oxidative modification of activated carbon for the adsorption behavior of nicotine

Kewu Pi,Min Xia,Pan Wu,Meichen Yang,Shuyu Chen,Defu Liu,Andrea R. Gerson 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.31 No.-

The adsorption of nicotine onto activated (AC) and AC modified (MAC, by contact with ammoniumpersulfate) can be described well using the Langmuir model with maximum adsorption capacities of 552and 640 mg g 1, respectively. Nicotine has high ‘hardness’ and appears to adsorb most readily on theincreased concentration of ‘hard’ MAC edge functional groups. Adsorption is shown to be exothermic;with enthalpy of 10 and 16 kJ mol 1 for AC and MAC, respectively. The negative free energy andpositive entropy of adsorption indicate a spontaneous process and a strong affinity between aqueousnicotine and AC or MAC.