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  • Author: Fei-Fei Chang x
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Fei-Fei Chang, Chang-Chieh Chen, Shao-Hung Wang and Chiou-Lin Chen

Abstract

Introduction: Laryngeal swab samples collected from three waterfowl slaughterhouses in central Taiwan were cultured and suspected isolates of Riemerella anatipestifer were identified by API 20NE and 16S rDNA PCR.

Material and Methods: Serum agglutination was used for serotyping, and antimicrobial susceptibility was tested.

Results: Seventy-six R. anatipestifer isolates were detected, and the prevalences in the ducks and geese were 12.3% (46/375) and 8.0% (30/375), respectively. The positive isolation rates were 65.6% for all arriving waterfowl, 76.0% for birds in the holding area, 1.6% for defeathered carcasses, but zero for degummed carcasses. A PCR examination detected R. anatipestifer in the slaughtering area frequently. Serotype B was dominant in both duck (34.8%) and goose (46.7%) isolates, but the wide serotype distribution may very well impede vaccination development. All isolates were resistant to colistin, and 79.7% were resistant to more than three common antibiotics.

Conclusion: The results proved that most ducks had encountered antibiotic-resistant R. anatipestifer in rearing, which suggests that the bacterium circulates in asymptomatic waterfowl. It is worth noting that most waterfowl farms were found to harbour R. anatipestifer, and contaminated slaughterhouses are a major risk factor in its spread. Effective prevention and containment measures should be established there to interrupt the transmission chain of R. anatipestifer.

Open access

Zinan Chang and Fei Shao

Abstract

Many immunization strategies have been proposed to control the epidemic spreading which mainly focus on how to immunize the nodes. A novel and efficient strategy to control the traffic driven epidemic spreading in weighted networks is proposed in this paper. By immunizing the edges according to different weights, our control strategies cannot only reduce the epidemic spreading velocity and enhance the critical epidemic threshold, but also maintain the integrity of the weighted networks. Simulations show that the control strategy by immunizing edges according to the product of the strengths of two nodes of the edge proved to be more efficient.

Open access

Wenzhi Chang, Fei Du, Jiangang Bi, Jin Shao, Jiang Peng, Jiping Liu and Haoming Wang

Abstract

To clarify the relationship between microporous defects and the development of partial discharge(PD) in silicone rubber, meanwhile evaluate insulation state of the prefabricated power cable joints quantitatively, the microporous defect is made based on real power cable joint, and PD signals are measured by step test method with the development of the defect. The discharge number, total energy and average energy of PD is gained to calculate the curves changed over time, based on which the breakdown process is divided into 4 stages, then phased spectra and grayscale maps are calculated for reflection of PD repetition rate and average energy in phase domain. Phase width, skewness of spectrum and coefficient of variation of parameter are employed to indicate the spectra statistical shape feature in each stage. The study indicates that the shape features of spectra are changed during the development of defect, the 3 features parameters are monotonously changed, and the changing rate is significantly higher at the end of the breakdown process. Evaluation method for micropores PD of silicon rubber is proposed based on the analysis of the parameters and the trend of PDs development.

Open access

Ya-Li Liu, Yao-Zhong Ding, Jun-Fei Dai, Bing Ma, Ji-Jun He, Wei-Min Ma, Jian-Liang Lv, Xiao-Yuan Ma, Yun-Wen Ou, Jun Wang, Yong-Sheng Liu, Hui-Yun Chang, Yong-Lu Wang, Qiang Zhang, Xiang-Tao Liu, Yong-Guang Zhang and Jie Zhang

Abstract

Introduction

The extremely high genetic variation and the continuously emerging variants of foot-and-mouth disease virus (FMDV) of Southern African Territory (SAT) serotypes including SAT1, SAT2, and SAT3 make it necessary to develop a new RT-PCR for general use for monitoring viruses based on the updated genome information.

Material and Methods

A FMDV SAT-D8 one-step RT-PCR was established based on the 1D2A2B genes of the SAT serotype viruses with a multiplex primer set. FMDV A, O, C, and Asia 1 serotypes, other vesicular disease viruses, inactivated SAT viruses, and 125 bovine, ovine, caprine and porcine tissue samples collected from the Chinese mainland were included for evaluating the assay.

Results

The new RT-PCR was proven to be specific without cross-reactions with Eurasian FMDV, swine vesicular disease virus (SVDV), Seneca valley virus (SVV), or other common viral pathogens of cattle, sheep, goat, and pig. An around 257 bp-sized amplicon clearly appeared when the inactivated SAT viruses were detected. However, all 125 samples collected from FMDV-susceptible animals from the Chinese mainland which has not known SAT epidemics showed negative results.

Conclusions

A FMDV SAT-D8 one-step RT-PCR is a promising method for primary screening for FMDV SAT serotypes.