Improving the Thermostability of α-Glucosidase from Xanthomonas campestris through Proline Substitutions Guided by Semi-rational Design

Luyi Chen,Kunyao Jiang,Yaoyao Zhou,Linjiang Zhu,Xiao-Long Chen 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.4

The α-glycosidase from Xanthomonas campestris (XgtA) can specifically catalyze the transglycosylation reactions, thus can be applied for the enzymatic synthesis of α-glycosides. However, the low thermal stability of XgtA has been a bottleneck for its industrial application. In this research, a combined semi-rational design strategy was used based on analysis of the α-helices and β-turns of XgtA, FireProt prediction of thermostable mutants and molecular dynamic simulations for improving the thermostability. The key positions with a significant impact on the thermal stability of XgtA were identified and the effect of proline substitution was tested. Five single-point mutants V167P, A177P, A210P, A220P, T345P, and a combined mutant Mut5 were obtained with improved thermal stability. Mut5 displayed a 3.06-fold increase in time of half-life at 45°C without impairing its initial hydrolytic activity. Molecular dynamics simulations revealed that changes in the flexibility of amino acid residues, newly-forming hydrogen bonding networks and hydrophobic interactions were responsible for the improved thermostability. These results suggest that proline substitution of key flexible positions is an effective strategy for improving enzyme thermostability.

Anti-pilling of Cashmere Knitted Fabric Based on Siloxane-Modified Chitosan

Wanyun Tian,Luyi Chen,Xue Zhang,Yarong Wu 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

In this study, chitosan was modified by two kinds of different siloxanes, γ-glycidoxypropyl-trimethoxysilane (GPTMS) and γ-glycidoxypropyl-dimethoxy- methylsilane (GPDMS), respectively, then applied for anti-pilling of cashmere knitted fabrics. The structure of the modified chitosan, the apparent morphology and the mechanical properties of the modified film were analyzed by FTIR, SEM and DMA, respectively. The hydrophilicity and swelling properties of the modified film were compared. The results showed that epoxy groups of siloxane reacted with amino groups of chitosan, and the –OR (R represents alkyl) groups of siloxane hydrolyzed and polycondensation conducted during the film-forming process. After modification, the mechanical properties of the film were more flexible, the hydrophilicity and swelling of the film was decreased. Cashmere knitted fabric was treated with the modified chitosan and glutathione was chosen as the model compound to explore the reaction between modified chitosan and cashmere fibers. The apparent morphology and elements distribution of the fibers were observed by SEM and EDS, respectively. The directional friction effect of the fibers was tested by fiber friction coefficient tester. The pilling grade, handle, whiteness and launderability of fabric were investigated. The results showed that the epoxy groups remaining in siloxane were reacted with the amino groups of cashmere fiber, which enhance the binding of the fiber and siloxane-modified chitosan, the siloxane-modified chitosan film formed on fibers in situ. The directional friction effect of the fiber significantly reduced, the tendency of fuzzes to the surface of the fabric was weakened and the probability of tangling of exposed fuzzings was reduced, the pilling grade of the fabric treated by modified chitosan reached level 4 and the fabrics had good launderability, the soft and smooth handle was still preserved. There was no obvious color difference of cashmere fabrics treated with siloxane-modified chitosan.

A Novel Coverage Holes Discovery Algorithm Based on Voronoi Diagram in Wireless Sensor Networks

Guoyong Dai,Hexin Lv,Luyi Chen,Binbin Zhou,Ping Xu 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.3

Coverage is a key and fundamental problem in wireless sensor networks. To provide high quality of service, high coverage ratio of sensor nodes in monitored area should be assured. Coverage holes may lead to routing failure and degrade the quality of service. A novel coverage hole discovery algorithm, VCHDA, is proposed for wireless sensor networks in this paper. The proposed algorithm is based on the well-known Voronoi diagram. It can recognize coverage holes and label the border nodes of coverage holes effectively. Simulations are conducted and the results show that the proposed algorithm is effective and with high accuracy.

The effects of cigarettes and alcohol on intestinal microbiota in healthy men

Lin Renbin,Zhang Yawen,Chen Luyi,Qi Yadong,He Jiamin,Hu Mengjia,Zhang Ying,Fan Lina,Yang Tao,Wang Lan,Si Misi,Chen Shujie 한국미생물학회 2020 The journal of microbiology Vol.58 No.11

Human intestinal microbiota is affected by the exogenous microenvironment. This study aimed to determine the effects of cigarettes and alcohol on the gut microbiota of healthy men. In total, 116 healthy male subjects were enrolled and divided into four groups: non-smoking and non-drinking (Group A), smoking only (Group B), drinking only (Group C), and smoking and drinking combined (Group D). Fecal samples were collected and sequenced using 16S rRNA to analyze the microbial composition. Short-chain fatty acid (SCFAs) levels in feces were determined by gas chromatography. We found that cigarette and alcohol consumptions can alter overall composition of gut microbiota in healthy men. The relative abundances of phylum Bacteroidetes and Firmicutes and more than 40 genera were changed with cigarette and alcohol consumptions. SCFAs decreased with smoking and alcohol consumption. Multivariate analysis indicated that when compared with group A, group B/C/D had higher Bacteroides, and lower Phascolarctobacterium, Ruminococcaceae_ UCG-002, Ruminococcaceae_UCG-003, and Ruminiclostridium_ 9 regardless of BMI and age. Additionally, the abundance of Bacteroides was positively correlated with the smoking pack-year (r = 0.207, p < 0.05), the abundance of predicted pathway of bacterial toxins (r = 0.3672, p < 0.001) and the level of carcinoembryonic antigen in host (r = 0.318, p < 0.01). Group D shared similar microbial construction with group B, but exerted differences far from group C with lower abundance of Haemophilus. These results demonstrated that cigarette and alcohol consumption separately affected the intestinal microbiota and function in healthy men; furthermore, the co-occurrence of cigarette and alcohol didn’t exacerbate the dysbiosis and cigarette played the predominated role on the alteration.

Few-shot link prediction with meta-learning for temporal knowledge graphs

Zhu Lin,Xing Yizong,Bai Luyi,Chen Xiwen 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2

With the deepening of the research on knowledge graph embedding, temporal knowledge graphs (TKGs), which are dynamic changes over time, have gradually gained the attention of researchers. Although some TKG-embedding models have been proposed, they did not perform well for certain relationships with insufficient samples, since they all require tremendous training samples. Thus, few-shot link prediction tasks, namely predicting new relation-specific quadruples by observing only a few samples, are still very challenging. In this paper, a method named meta-reasoning for TKGs (MetaRT) is proposed to solve this universal but challenging problem. MetaRT works by extracting the meta-information of a specific relation and updating it quickly, so that the model can learn the most critical information in TKG swiftly and independently. In the meantime, temporal information can be managed well by a TKG learner. Finally, through a large number of experiments, it shows that MetaRT outperforms other existing TKG-embedding models on the problem of few-shot learning.

Research on Pilling Performance of Cashmere Knitted Fabric Based on Fiber Frictional Properties

Yarong Wu,Wanyun Tian,Xue Zhang,Gui Liu,Luyi Chen 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

Pilling of cashmere knitted fabric has always been and being a tough problem; the scales available on the cashmere fiber surface and the as-resulted special frictional effect were one of the main reasons for pilling. In this research, the frictional coefficients [with-scale static coefficient (μws), with-scale dynamic coefficient (μwd), anti-scale static coefficient (μas), anti-scale dynamic coefficient (μad), μas- μws, μad-μwd, (μas- μws)/(μas+μws) and (μad- μwd)/(μad+μwd)] of cashmere fiber were measured by capstan method, and the conditions for measuring were optimized. On this basis, eight kinds of typical chemical or biological (protease) treatments were selected for anti-pilling treatment of cashmere knitted fabric, and the frictional coefficients of cashmere fiber under these treatments were measured. The surface morphology and the surface hairiness of cashmere were observed by scanning electron microscope (SEM) and ultra-depth of field microscope, respectively. The pilling performance of these treated knitted fabrics was conducted by means of pilling box method. The effect of different chemical/biological treatments on the frictional properties of fibers and the relationship between frictional properties and pilling performance were analyzed based on OLS regression analysis and independent sample t test using Stata 16.0. Experimental results showed that there was a good correlation between the pilling performance of cashmere fabric and the value of μad- μwd. When considering the specific chemical/biologic treatments, different treatments possessed different effects on the specific indicators of fiber frictional performance; so, for different treatment processes, different frictional coefficients could be selected to assist the evaluation of fabric pilling performance.

Artificial Intelligence in the Prediction of Gastrointestinal Stromal Tumors on Endoscopic Ultrasonography Images: Development, Validation and Comparison with Endosonographers

Lu Yi,Wu Jiachuan,Hu Minhui,Zhong Qinghua,Er Limian,Shi Huihui,Cheng Weihui,Chen Ke,Liu Yuan,Qiu Bingfeng,Xu Qiancheng,Lai Guangshun,Wang Yufeng,Luo Yuxuan,Mu Jinbao,Zhang Wenjie,Zhi Min,Sun Jiachen 거트앤리버 소화기연관학회협의회 2023 Gut and Liver Vol.17 No.6

Background/Aims: The accuracy of endosonographers in diagnosing gastric subepithelial lesions (SELs) using endoscopic ultrasonography (EUS) is influenced by experience and subjectivity. Artificial intelligence (AI) has achieved remarkable development in this field. This study aimed to develop an AI-based EUS diagnostic model for the diagnosis of SELs, and evaluated its efficacy with external validation. Methods: We developed the EUS-AI model with ResNeSt50 using EUS images from two hospitals to predict the histopathology of the gastric SELs originating from muscularis propria. The diagnostic performance of the model was also validated using EUS images obtained from four other hospitals. Results: A total of 2,057 images from 367 patients (375 SELs) were chosen to build the models, and 914 images from 106 patients (108 SELs) were chosen for external validation. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the model for differentiating gastrointestinal stromal tumors (GISTs) and non-GISTs in the external validation sets by images were 82.01%, 68.22%, 86.77%, 59.86%, and 78.12%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the external validation set by tumors were 83.75%, 71.43%, 89.33%, 60.61%, and 80.56%, respectively. The EUS-AI model showed better performance (especially specificity) than some endosonographers. The model helped improve the sensitivity, specificity, and accuracy of certain endosonographers. Conclusions: We developed an EUS-AI model to classify gastric SELs originating from muscularis propria into GISTs and non-GISTs with good accuracy. The model may help improve the diagnostic performance of endosonographers. Further work is required to develop a multi-modal EUS-AI system.