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Number of results: 8
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Abstract

The study was aimed to develop an indirect enzyme-linked immunosorbent assay (ELISA), which can detect specifically Feline herpesvirus type 1 (FHV-1). The primers were designed based on the conserved sequence of FHV-1 glycoprotein B gene. The recombinant protein with reactogenicity was purified as coating antigen of the assay. The indirect ELISA, characterized by high sensitivity showed no cross-reaction with two types of feline virus, had detection limit at 1:2000 dilution. The positive rate of the assay, according to the determined cutoff value (0.25), was basically consistent with Feline Herpes Virus Antibody ELISA kit. In conclusion, the indirect ELISA with high repeatability and reproducibility can be used for detecting FHV-1, and can provide necessary support to related research.
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Abstract

Laplace Transform is often used in solving the free vibration problems of structural beams. In existing research, there are two types of simplified models of continuous beam placement. The first is to regard the continuous beam as a single-span beam, the middle bearing of which is replaced by the bearing reaction force; the second is to divide the continuous beam into several simply supported beams, with the bending moment of the continuous beam at the middle bearing considered as the external force. Research shows that the second simplified model is incorrect, and the frequency equation derived from the first simplified model contains multiple expressions which might not be equivalent to each other. This paper specifies the application method of Laplace Transform in solving the free vibration problems of continuous beams, having great significance in the proper use of the transform method.
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Abstract

In this study, medium-carbon steel was subjected to warm deformation experiments on a Gleeble 3500 thermosimulator machine at temperatures of 550°C and 650°C and strain rates of 0.001 s–1 to 1 s–1. The warm deformation behavior of martensite and the effects of strain rate on the microstructure of ultrafine grained medium-carbon steel were investigated. The precipitation behavior of Fe3C during deformation was analyzed and the results showed that recrystallization occurred at a low strain rate. The average ultrafine ferrite grains of 500 ± 58 nm were fabricated at 550°C and a strain rate of 0.001 s–1. In addition, the size of Fe3C particles in the ferrite grains did not show any apparent change, while that of the Fe3C particles at the grain boundaries was mainly affected by the deformation temperature. The size of Fe3C particles increased with the increasing deformation temperature, while the strain rate had no significant effect on Fe3C particles. Moreover, the grain size of recrystallized ferrite decreased with an increase in the strain rate. The effects of the strain rate on the grain size of recrystallized ferrite depended on the deformation temperature and the strain rate had a prominent effect on the grain size at 550°C deformation temperature. Finally, the deformation resistance apparently decreased at 550°C and strain rate of 1 s–1 due to the maximum adiabatic heating in the material.
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Abstract

In vitro embryogenic callus is a critical factor for genetic transformation of rice, especially for indica varieties. In this study, we investigated the relationship between polyamines, including putrescine (Put), spermidine (Spd) and spermine (Spm), and callus browning, and we studied the effect of exogenous Put on callus regeneration and on the content of endogenous polyamines. In addition, the expression levels of arginine decarboxylase gene (Adcl) and S-adenosylmethionine decarboxylase gene (Samdc) in embryogenic callus were studied by quantitative Real-time PCR analysis. The results showed that the contents of endogenous Put and Spd in the browning callus were significantly lower than those in normal callus. Exogenous Put could effectively improve the growing state of callus of indica rice and enhance the development of embryogenic callus. The content of endogenous polyamines in embryogenic callus, especially Spd and Spm, was increased after addition of exogenous Put. Additionally, exogenous Put also had an obvious impact on the expression levels of Adcl but partial effect on the expression levels of Samdc gene. This study could increase the knowledge of both embryogenic callus induction and polyamine catabolism in callus in indica rice.
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Abstract

In order to understand infection of avian influenza A virus (AIV) and canine distemper virus (CDV) in the Siberian Tiger in Northeast China, 75 Siberian Tiger serum samples from three cap- tive facilities in northeastern China were collected. AIV and CDV antibody surveillance was test- ed by using hemagglutination inhibition and serum neutralization methods. The results showed that the seroprevalence of H5 AIV, H9 AIV and CDV was respectively 9.33% (7/75), 61.33% (46/75) and 16% (12/75). In the 1<years <2 and > 5 year-old group, the seroprevalence of the H9 AIV was 24% and 80% (P < 0.01), and the CDV seroprevalence was 6% and 36% (P < 0.01), respectively. It was demonstrated that 3 (4%) out of 75 serum samples were AIV+CDV seropos- itive, with 2.67% (2/75) in H9+AIV and 1.33% (1/75) in H5+H9+AIV. To our knowledge, this is the first report of AIV and CDV seroprevalence in Siberian Tigers in China, which will provide base-line data for the control of AIV and CDV infection in Siberian Tigers in China.
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