Evolution of E. coli Phytase for Increased Thermostability Guided by Rational Parameters

( Jiadi Li ),( Xinli Li ),( Yuanming Gai ),( Yumei Sun ),( Dawei Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.3

Phytases are enzymes that can hydrolyze phytate and its salts into inositol and phosphoric acid, and have been utilized to increase the availability of nutrients in animal feed and mitigate environmental pollution. However, the enzymes’ low thermostability has limited their application during the feed palletization process. In this study, a combination of B-value calculation and protein surface engineering was applied to rationally evolve the heat stability of Escherichia coli phytase. After systematic alignment and mining for homologs of the original phytase from the histidine acid phosphatase family, the two models 1DKL and 1DKQ were chosen and used to identify the B-values and spatial distribution of key amino acid residues. Consequently, thirteen potential amino acid mutation sites were obtained and categorized into six domains to construct mutant libraries. After five rounds of iterative mutation screening, the thermophilic phytase mutant P56214 was finally yielded. Compared with the wild-type, the residual enzyme activity of the mutant increased from 20% to 75% after incubation at 90°C for 5 min. Compared with traditional methods, the rational engineering approach used in this study reduces the screening workload and provides a reference for future applications of phytases as green catalysts.

Research on User Identification Algorithm based on Rewriting URL

Zhou Jiadi,Geng Hai 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.3

The Naive Bayesian Algorithm-based Prisoner’s Dilemma Game Model

Xiuqin Deng,Jiadi Deng 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.6

Prisoners’ dilemma is a typical game theory issue. In this study, it was treated as an incomplete information game to establish a related machine learning model using a naive Bayesian classification method. The model established was referred to as the Bayes model. Using this model, the incomplete information game was soluble with the assistance of statistical machine learning. This study proceeded as follows: firstly, four typical models were run against the Bayes model some 10,000 times. The total incomes of the models recorded suggested that Bayes model was more advantageous than other models. Even in a multi-player prisoners’ game, Bayes model also presented the desired level of performance and accrued a higher income than other models. Further statistical analysis implied that the Bayes model and the widely accepted optimum strategy tit-for-tat (TFT) model showed a tendency to be prone to defection. Secondly, according to the games run on the natural Bayes model, as well as the natural TFT model, it was found that the Bayes model accrued more benefits than the TFT model on average. Finally, comparison of the Bayes model with the TFT model revealed that the Bayes model was better. This demonstrated the efficacy of the Bayes model constructed in this study and moreover, provided a novel idea for solving the problem of an incomplete information game.

Application of Near-Infrared Fluorescence Imaging with Indocyanine Green in Totally Laparoscopic Distal Gastrectomy

Maoxing Liu,Jiadi Xing,Kai Xu,Peng Yuan,Ming Cui,Chenghai Zhang,Hong Yang,Zhendan Yao,Nan Zhang,Fei Tan,Xiangqian Su 대한위암학회 2020 Journal of gastric cancer Vol.20 No.3

aPurpose: Recently, totally laparoscopic gastrectomy has been gradually accepted by surgeons worldwide for gastric cancer treatment. Complete dissection of the lymph nodes and the establishment of the surgical margin are the most important considerations for curative gastric cancer surgery. Previous studies have demonstrated that indocyanine green (ICG)-traced laparoscopic gastrectomy significantly improves the completeness of lymph node dissection. However, it remains difficult to identify the tumor location intraoperatively for gastric cancers that are staged ≤T3. Here, we investigated the feasibility of ICG fluorescence for lymph node mapping and tumor localization during totally laparoscopic distal gastrectomy. Materials and Methods: Preoperative and perioperative data from consecutive patients with gastric cancer who underwent a totally laparoscopic distal gastrectomy were collected and analyzed. The patients were categorized into the ICG (n=61) or the non-ICG (n=75) group based on whether preoperative endoscopic mucosal ICG injection was performed. Results: The ICG group had a shorter operation time and less intraoperative blood loss. Moreover, significantly more lymph nodes were harvested in the ICG group than the non-ICG group. No pathologically positive margin was found and there was no significant difference in either the proximal or distal surgical margins between the 2 groups. Conclusions: Near-infrared fluorescence imaging with ICG can be successfully used in totally laparoscopic distal gastrectomy, and it contributes to both the completeness of D2 lymph node dissection and confirmation of the gastric transection line. Well-designed prospective randomized studies are needed in the future to fully validate our findings.

Droplet transient migration and dynamic force balance mechanism on vibration-controlled micro-texture surfaces

Jing Xu,Guodong Liu,Jiadi Lian,Jing Ni,Jing Xiao 한국물리학회 2018 Current Applied Physics Vol.18 No.11

In this paper, forced vibration was used to regulate the droplet migration, fully recording the transient migration of droplets on a micro-textured substrate under the resonance frequency by a high-speed camera. The influence of resonance frequency and dynamic migration characteristics of droplets on the solid micro-texture surface under lateral vibration were researched. The experiment demonstrates that the driving force is caused by the difference between the left and right contact angles made the droplet oscillate and migrate, and as time t increases, the left and right contact points are periodically shifted and the amplitude of migration increases. Therefore, based on the droplet migration behavior and its force balance mechanism, a spring vibration model of migration behavior of the vibrating droplet micro unit was set up to predict the complete trajectory of its migration on a solid surface. The calculation results show that the theoretical displacement is less than the experimental displacement, and the longer the time, the larger the difference. Affected by the vibration, part of the droplet permeates through the micro-texture, resulting in the droplet losing height and the contact angle becoming smaller as well. While the other part of droplet overcomes the internal surface tension to migrate.

Experimental study on seismic behavior of two-storey modular structure

Yang Liu,Zhihua Chen,Jiadi Liu,Xu Zhong 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.3

Due to the unique construction method of modular steel buildings (MSBs) with units prefabricated fully off the site and assembled quickly on the site, the inter-module connection for easy operation and overall performance of the system were key issues. However, it was a lack of relevant research on the system-level performance of MSBs. This study investigated the seismic performance of two-storey modular steel structure with a proposed vertical rotary inter-module connection. Three full-scale quasi-static tests, with and without corrugated steel plate and its combination, were carried out to evaluate and compare their seismic behaviour. The hysteretic performance, skeleton curves, ductile performance, stiffness degradation, energy dissipation capacity, and deformation pattern were clarified. The results showed that good ductility and plastic deformation ability of such modular steel structures. Two lateral-force resistance mechanisms with different layout combinations were also discussed in detail. The corrugated steel plate could significantly improve the lateral stiffness and bearing capacity of the modular steel structure. The cooperative working mechanism of modules and inter-module connections was further analyzed. When the lateral stiffness of upper and lower modular structures was close, limited bending moment transfer may be considered for the inter-module connection. While a large lateral stiffness difference existed initially between the upper and lower structures, an obvious gap occurred at the inter-module connection, and this gap may significantly influence the bending moments transferred by the inter-module connections. Meanwhile, several design recommendations of inter-module connections were also given for the application of MSBs.

Analytical and Design Method for the Global Stability of Modular Steel Buildings

Zhi-Hua Chen,Xu Zhong,Yang Liu,Jiadi Liu 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

Modular steel buildings (MSBs) are an innovative form of prefabricated buildings with many advantages related to the factory-manufactured construction process. However, technical issues in the global stability design remain ambiguous and induce either unsuitable or uneconomical results without understanding the eff ect of intermodule connections appropriately. In this study, one practical theoretical equation to determine the buckling length factor for the sway-permitted MSB was derived from a sub-assembly considering pinned or rigid inter-module connections. A large number of fi nite element models were then used to numerically validate the eff ectiveness of the theoretical equation and explore the main infl uencing factors including both intermodule connections and height-to-width ratios. Results indicated that the intermodule connections should be carefully considered when the fl oor beams are obviously larger than ceiling beams, and theoretical results can be accurate enough when the height-to-width ratios remain within 3.0. Moreover, the second-order analysis method for MSB was also performed by using nonlinear buckling analyses and then compared with the buckling length method to verify the previous fi ndings. Finally, the criterion in selecting the proper stability design procedure for MSB was discussed in depth.

On Deploying Relays for Connected Indoor Sensor Networks

Yanmin Zhu,Cuiyao Xue,Haibin Cai,Jiadi Yu,Lei Ni,Minglu Li,Bo Li 한국통신학회 2014 Journal of communications and networks Vol.16 No.3

This paper considers the crucial problem of deployingwireless relays for achieving a connected wireless sensor networkin indoor environments, an important aspect related to the managementof the sensor network. Several algorithms have been proposedfor ensuring full sensing coverage and network connectivity. These algorithms are not applicable to indoor environments becauseof the complexity of indoor environments, in which a radiosignal can be dramatically degraded by obstacles such as walls.Wefirst prove theoretically that the indoor relay placement problem isNP-hard. We then predict the radio coverage of a given relay deploymentin indoor environments. We consider two practical scenarios;wire-connected relays and radio-connected relays. For thenetwork with wire-connected relays, we propose an efficient greedyalgorithmto compute the deployment locations of relays for achievingthe required coverage percentage. This algorithm is proved toprovide a Hn factor approximation to the theoretical optimum,whereHn = 1+ 12 +· · ·+ 1n = ln(n)+1, and n is the number ofall grid points. In the network with radio-connected relays, relayshave to be connected in an ad hoc mode. We then propose an algorithmbased on the previous algorithm for ensuring the connectivityof relays. Experimental results demonstrate that the proposedalgorithms achieve better performance than baseline algorithms.

Insight into Fundamental Rules of Phenylenediamines Selective Monoacylation by the Comparisons of Kinetic Characteristics in Microreactor

Xu Qilin,Liu Ji Ming,Yao Hongmiao,Zhao Jinyang,Wang Zhikuo,Liu Junli,Zhou Jiadi,Yu Zhiqun,Su Weike 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.10

In this paper, the kinetics of acylation reaction of o-phenylenediamine/p-phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre-exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%.