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Open access

Feng Xue and Jian Gao

Abstract

The enantioselective resolution of racemic styrene oxide (rac-SO) to (R)-SO by whole cells of a recombinant Escherichia coli expressing epoxide hydrolase (EH) activity in aqueous and biphasic system were studied. Some parameters that may alter this bio-resolution, such as the concentration of recombinant cell, substrate and product were evaluated. The effect of the addition of different additives on the course of rac-SO biotransformation was also investigated. The results showed that the yield and the enantiomeric excess (ee) of (R)-SO were dependent on these variables. When the kinetic resolution was conducted with 350 mM of rac-SO, enantiopure (R)-SO with high (≥99%) ee was obtained with a yield of 38.2% yield at 12.2 h in the presence of 10% (v/v) Tween 80. An isooctane/aqueous system was developed to overcome the adverse factors in the aqueous phase, resulting in an improvement of yield from 38.2% to 42.9%. The results will provide a useful guidance for further application of this enzyme in the biocatalytic production of chiral synthons.

Open access

Feng Jian and Shi Dandan

Abstract

Advances in complex networks of Peer-to-Peer (P2P) networks were reviewed and summarized. The paper outlines some important topological properties such as degree, average path length and clustering coefficient at first, and then three kinds of most important network mechanism models are introduced, including random graph model, small world model and scale-free model. A simple description about research status for P2P networks based on complex networks is made from three aspects: positive research, network mechanism model, network broadcast and control. Some developing prospects of complex networks of P2P are pointed out finally. Complex network provides new ideas and methods to deal with many complex problems including P2P networks.

Open access

Zhi Gang Wu, Yan Rong Jia, Jian Wang, Yang Guo and Jian Feng Gao

Abstract

Core-shell SiO2/Ag composite spheres with dense, complete and nanoscaled silver shell were prepared by using a novel facile chemical reduction method without surface modification of silica at room temperature. The core-shell composites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy and energy dispersive X-ray spectroscopy (EDX). The photocatalytic properties towards the degradation of methyl orange (Mo) of the prepared SiO2/Ag composites were also tested. The studies showed that the surface of SiO2 microspheres was homogeneously and completely covered by Ag nanoparticles and the composite exhibited excellent photocatalytic activities. The possible reaction mechanisms for the formation of the silica-silver core-shell spheres were also discussed in this paper.

Open access

Jian Yang, Jinfu Feng, Yongli Li, An Liu, Junhua Hu and Zongcheng Ma

Abstract

In the process that the submarine-launched missile exits the water, there is the complex fluid solid coupling phenomenon. Therefore, it is difficult to establish the accurate water-exit dynamic model. In the paper, according to the characteristics of the water-exit motion, based on the traditional method of added mass, considering the added mass changing rate, the water-exit dynamic model is established. And with help of the CFX fluid simulation software, a new calculation method of the added mass that is suit for submarine-launched missile is proposed, which can effectively solve the problem of fluid solid coupling in modeling process. Then by the new calculation method, the change law of the added mass in water-exit process of the missile is obtained. In simulated analysis, for the water-exit process of the missile, by comparing the results of the numerical simulation and the calculation of theoretical model, the effectiveness of the new added mass calculation method and the accuracy of the water-exit dynamic model that considers the added mass changing rate are verified.

Open access

Xu-hu Wang, Jian-feng Chen, Jing Han and Ya-meng Jiao

Abstract

The optimization techniques are explored in the direction of arrival (DOA) estimation based on single acoustic pressure gradient vector sensor (APGVS). By analyzing the working principle and measurement errors of the APGVS, acoustic intensity approaches (AI) and the minimum variance distortionless response beamforming approach based on single APGVS (VMVDR) are deduced. The radius to wavelength ratio of the APGVS must be not bigger than 0.1 in the actual application, otherwise its DOA estimation performance will degrade significantly. To improve the ro-bustness and estimation performance of the DOA estimation approaches based on single APGVS, two modified proce-ssing approaches based on single APGVS are presented. Simulation and lake trial results indicate that the performance of the modified approaches based on single APGVS are better than AI and VMVDR approaches based on single APGVS when the radius to wavelength ratio is not bigger than 0.1, and the two modified DOA estimation methods have excel¬lent estimation performance when the radius to wavelength ratio is bigger than 0.1.

Open access

Wei-feng Zhou, An-zhou Li, Shi-jian Ji and Yong-song Qiu

Abstract

Using the yellowfin tuna (Thunnusalbacares,YFT)longline fishing catch data in the open South China Sea (SCS) provided by WCPFC, the optimum interpolation sea surface temperature (OISST) from CPC/NOAA and multi-satellites altimetric monthly averaged product sea surface height (SSH) released by CNES, eight alternative options based on Bayes classifier were made in this paper according to different strategies on the choice of environment factors and the levels of fishing zones to classify the YFT fishing ground in the open SCS. The classification results were compared with the actual ones for validation and analyzed to know how different plans impact on classification results and precision. The results of validation showed that the precision of the eight options were 71.4%, 75%, 70.8%, 74.4%, 66.7%, 68.5%, 57.7% and 63.7% in sequence, the first to sixth among them above 65% would meet the practical application needs basically. The alternatives which use SST and SSH simultaneously as the environmental factors have higher precision than which only use single SST environmental factor, and the consideration of adding SSH can improve the model precision to a certain extent. The options which use CPUE’s mean ± standard deviation as threshold have higher precision than which use CPUE’s 33.3%-quantile and 66.7%-quantile as the threshold

Open access

Feng-feng Kang, Shu-yan Cao, Yan-ming Li, Jiang-tao Li, Qing He, Yi Li and Yun-jian Hu

Abstract

Objective To investigate the clinical application of Real-Time PCR for rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) directly from nasopharyngeal swab specimens.

Methods We collected the nasal and throat swab specimens from patients or medical staffs in 3 intensive care units, blood laminar flow ward and respiratory ward in Beijing Hospital, Ministry of Health from December 2010 to April 2011. Each sample was tested by RT-PCR and conventional culture-based method for the presence of MRSA.

Results The total number of the specimens was 206. Compared with the conventional culture-based method, we demonstrated the diagnostic values for Real-Time PCR were 96.4% sensitivity, 96.6% specificity, 81.8% positive predictive rate, and 99.4% negative predictive rate. And the limit of detection was 102CFU/ml.

Conclusions This Real-Time PCR is a simple, rapid, sensitive and specific method. With the high negative predictive value, it can be used for the exclusion of MRSA colonization or infection. However, the application of its low positive predictive value should be further evaluated.

Open access

Jian-Tao Zhang, Jing-Tao Shao, Yun-Feng Liu and Hong-Bin Wang

Abstract

Ten mixed-breed female dogs were used in the study. Abdominal wall lifting was performed with a sterilised cotton strip. Four portal sites were used to complete gasless laparoscopic ovariohysterectomy (GLOHE) procedures. The proper and suspensor ligament, ovarian pedicle, and broad ligament of the uterus, uterine artery and vein were coagulated using bipolar electrocoagulation. After the uterine body was coagulated and cut, the end of the cervix was ligated with a loop suture. Blood samples were obtained before the surgery, immediately after the procedure, and on 1, 3, and 5 d postoperatively for the determination of interleukin-6 (IL-6) and C-reactive protein (CRP). No significant surgical complications occurred. After gasless laparoscopic ovariohysterectomy, a significantly higher serum IL-6 level was found immediately after the surgery and 1 d postoperatively when compared with the level observed after traditional laparoscopic ovariohysterectomy (LOHE). However, no significant differences were observed in CRP level between GLOHE and LOHE. GLOHE proved to be a safe and feasible procedure in bitches.