http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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>
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.
Screening and Cloning of RAPD Markers from the W Chromosome of Silkworm, Bombyx mori L.
( Chun Xia Zhang ),( Qin Yao ),( Qing Gang Xu ),( Xu Dong Tang ),( Ke Ping Chen ) 한국잠사학회 2007 International Journal of Industrial Entomology Vol.8 No.2
Silkworms sex determination drew high attention from researchers. Sex chromosomes on the silkworm are of ZW type for females and ZZ type for males. Chromosome W plays an important role in sex determination. Although several molecular linkage maps have been constructed for silkworm, very few markers are discovered on the W chromosome. In order to look for molecular markers and to further locate the Fem gene on chromosome W, we used genomic DNA from both female and male larvae of a silkworm strain named 937 as PCR templates for RAPD amplification with 200 arbitrary 10-mer primers. The amplification results showed three female-specific bands, namely OPG-07(496), OPC-15(1,660) and OPE-18(1,279). Further verification, however, revealed no band from OPG-07 and OPC-15 in either sex in the strain 798, but OPE-18 provided female-specific band in the strains Suluan7 and C108, and absent in both males and strain 798. This indicates that the bands from OPG-07(496) and OPC-15(1,660) are probably female-specific in strain 937, and the band from OPE-18 was probably amplified from a common segment shared by most strains. The genomic DNAs from OPG-07 and OPC-15 were cloned and sequenced. Sequence analysis showed that the DNAs from OPG-07 and OPC-15 have high identities with the retrotransposable elements, and DNA from OPC-15 contains a portion of sequence which probably encodes an eukaryotic translation initiation factor 4E binding protein (eIF4EBP).
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.