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Metabolic engineering of Escherichia coli for the production of putrescine: A four carbon diamine
Qian, Zhi-Gang,Xia, Xiao-Xia,Lee, Sang Yup Wiley Subscription Services, Inc., A Wiley Company 2009 Biotechnology and bioengineering Vol.104 No.4
<P>A four carbon linear chain diamine, putrescine (1,4-diaminobutane), is an important platform chemical having a wide range of applications in chemical industry. Biotechnological production of putrescine from renewable feedstock is a promising alternative to the chemical synthesis that originates from non-renewable petroleum. Here we report development of a metabolically engineered strain of Escherichia coli that produces putrescine at high titer in glucose mineral salts medium. First, a base strain was constructed by inactivating the putrescine degradation and utilization pathways, and deleting the ornithine carbamoyltransferase chain I gene argI to make more precursors available for putrescine synthesis. Next, ornithine decarboxylase, which converts ornithine to putrescine, was amplified by a combination of plasmid-based and chromosome-based overexpression of the coding genes under the strong tac or trc promoter. Furthermore, the ornithine biosynthetic genes (argC-E) were overexpressed from the trc promoter, which replaced the native promoter in the genome, to increase the ornithine pool. Finally, strain performance was further improved by the deletion of the stress responsive RNA polymerase sigma factor RpoS, a well-known global transcription regulator that controls the expression of ca. 10% of the E. coli genes. The final engineered E. coli strain was able to produce 1.68 g L<SUP>−1</SUP> of putrescine with a yield of 0.168 g g<SUP>−1</SUP> glucose. Furthermore, high cell density cultivation allowed production of 24.2 g L<SUP>−1</SUP> of putrescine with a productivity of 0.75 g L<SUP>−1</SUP> h<SUP>−1</SUP>. The strategy reported here should be useful for the bio-based production of putrescine from renewable resources, and also for the development of strains capable of producing other diamines, which are important as nitrogen-containing platform chemicals. Biotechnol. Bioeng. 2009; 104: 651–662 © 2009 Wiley Periodicals, Inc.</P>
Celebrity Endorsement Problem on Social Media : Formulation, Analysis and Recommendation Algorithm
Lv Hai-xia,Yu Guang,Wu Gang 보안공학연구지원센터(IJUNESST) 2015 International Journal of u- and e- Service, Scienc Vol.8 No.1
In this paper, a new matching recommendation algorithm is proposed to help enterprises find one or more proper celebrities from social media for their product endorsement. The fans group of a celebrity, his impaction value in the social media, as well as the matching degree between the celebrity and the product are selected to measure a celebrity. The attribute similarities between target customers of the product and fans of the celebrity are calculated via the Pearson similarity formula. Then, considering the impaction value of the celebrity and the matching degree of the celebrity and the product which can be accessed on the website or usually available from the enterprise, an evaluation index is proposed. We use some data from Sina Micro-blog, which is the most popular social media platform in China, to show the effectiveness of our proposed matching recommendation algorithm. Moreover, the analysis shows that a particular celebrity may suitable to endorse different product on-line and off-line.
ISAR 2-D Imaging of Uniformly Rotating Targets via Matching Pursuit
Gang Li,Hao Zhang,Xiqin Wang,Xiang-Gen Xia IEEE 2012 IEEE transactions on aerospace and electronic syst Vol.48 No.2
<P>An algorithm based on matching pursuit (MP) is proposed for inverse synthetic aperture radar (ISAR) two-dimensional (2-D) imaging of uniformly rotating targets. The ISAR echo is decomposed into many subsignals that are generated by discretizing spatial domain and synthesizing the ISAR data for every discretized spatial position. The subsignals that indeed contribute to the ISAR echo are selected by the MP, and their coefficients represent the superresolution image. The target rotation rate is estimated by combining MP with maximum contrast search.</P>
Zhang, Gang,Xia, Tian,Zhao, Jinbiao,Liu, Ling,He, Pingli,Zhang, Shuai,Zhang, Liying Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.2
Objective: Two experiments were conducted to evaluate tetrabasic zinc chloride (TBZC) on the health of weaned pigs, and to determine the optimal supplemental concentrations and whether dietary TBZC could replace the pharmacological concentrations of dietary zinc oxide (ZnO) to improve growth performance and decrease Zn excretion in weaned pigs. Methods: In Exp. 1, 180 weaned pigs (8.92±1.05 kg body weight [BW]) were randomly assigned to 1 of 5 treatments, including the basal diet containing 125 mg/kg zinc sulfate (ZnSO<sub>4</sub>), and the basal diet with 1,200, 1,800, 2,400, or 3,000 mg/kg TBZC supplementation. In Exp. 2, 240 weaned pigs (7.66±1.09 kg BW) were randomly assigned to 1 of 5 treatments, including a negative control diet without Zn supplementation, a positive control diet (2,250 mg/kg ZnO), and 3 experimental diets with different concentrations of TBZC supplementation (1,000, 1,250, and 1,500 mg/kg). Results: In Exp. 1, the average daily gain (ADG), feed efficiency (G:F) and diarrhea incidence responded quadratically (p<0.01) as the TBZC supplemental concentrations increased, and pigs fed 1,200 and 1,800 mg/kg TBZC showed the best growth performance. Moreover, 1,800 mg/kg TBZC supplementation showed the greatest (p<0.01) total antioxidant capacity and glutathione peroxidase activities in liver of pigs. Histopathological examination revealed lesions in heart, liver, lung and kidney, and mild or severe histological lesions mainly occurred with the supplementation of 2,400 and 3,000 mg/kg TBZC. In Exp. 2, 1,000 and 1,250 mg/kg TBZC supplementation in diets significantly (p<0.01) increased ADG and G:F of weaned pigs, reduced Zn excretion in feces, and had no effect on diarrhea-reducing compared to 2,250 mg/kg ZnO supplementation. Conclusion: The TBZC is a potential alternative to ZnO. The recommended concentration of TBZC in weaned pig diets is 1,000 to 1,250 mg/kg.
Three New Oleanane-Type Triterpene Saponins from Gladiolus gandavensis
Zhi-Gang Tai,Le Cai,Ya-Bin Yang,Chuan-Shui Liu,Jian-Jun Xia,Zhong-Tao Ding 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.10
Three new oleanane-type triterpene saponins (1, 2 and 3) were isolated from aerial parts of Gladiolus gandavensis,along with two known compounds (4 and 5). Their structures were elucidated as 29-O-(β-D-glucopyranosyl)-2β,3β-dihydroxyolean-12-en-28-oicacid(1), 3-O-(β-D-xylopyranosyl)-29-O-(β-D-glucopyranosyl)-12-en-28-oic acid (2),and 2β,3β,29-trihydroxyolean-12-en-28-oic acid 28-O-[β-D-glucopyranosyl(1→2)-(α-L-rhamnopyranosyl(1→6))-β-D-glucopyranosyl] ester (3), by spectroscopic methods, and by comparison with known analogues. These oleanane-type triterpene saponins glycosidated at C-29 were not obtained frequently.
A Key Pre-distribution Scheme Based on Deployment Information
Shulan Xia,Jilin Wang,Ru-gang Wang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.11
A scheme of grouping key distribution based on polynomial protocol is proposed and experimentally demonstrated. The grouping idea is ingeniously used in the design of key distribution. The performance is experimental demonstrated by comparing with kinds of random key pre-distribution schemes. The results show that it can not only guarantee the key connected rate but also strengthen the security performance of the network, and this scheme is very suitable for static underwater acoustic communications network.
An Improved Algorithm of Speech Emotion Recognition
Shulan Xia,Jilin Wang,Ru-gang Wang,Li Zhao 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.12
The traditional K-nearest neighbor algorithm existences of the risk of miscarriage of justice, for its shortage a speech emotion recognition algorithm based on fuzzy K-nearest neighbors is proposed. By introducing the fuzzy membership concept, different characteristic parameters for the different contribution of emotion recognition are calculated, and the weighted Euclidean distance is used in speech emotion recognition. The experimental results show the effectiveness of the algorithm.