1.6-µm-wavelength dissipative solitons mode-locked fiber laser based on the optimization of passive fibers distribution.

We present the results of numerical simulation of a dissipative solitons mode-locked fiber laser working over 1.6 µm. First, systematic and computationally intensive analysis of high-energy-pulse nonlinear phase shift of a fiber laser was conducted, and we numerically simulated dissipative solitons pulse evolution. In addition, we employed a method named A/B ratio to decrease B-integral by changing the distribution of passive fiber in the ring cavity. This method inhibited the accumulation of nonlinear phase shift and effectively enlarged the pulse energy from 0.8 nJ to 3.6 nJ. Finally, we optimized linear chirp of the pulse by using a designed larger-mode-area fiber, and ultimately a 2.82-kW, 650-fs pulse was obtained.

Seroprevalence and risk factors of hepatitis E virus infection among the Korean, Manchu, Mongol, and Han ethnic groups in Eastern and Northeastern China.

Hepatitis E virus (HEV) infection is a serious public health concern in developing countries. China is regarded as an HEV-endemic area, but epidemiological data for HEV among different nationalities is limited. This study was conducted to estimate the seroprevalence and risk factors of HEV infection in Koreans (n = 520), Manchus (n = 303), Mongols (n = 217), and Hans (n = 802) in Eastern and Northeastern China between 2013 and 2015. A total of 366 (19.87%) out of 1842 samples were seropositive for IgG or IgM HEV-antibodies detected by enzyme-linked immunoassays. Among these groups, the Mongols had the highest seroprevalence of HEV infection (25.35%, 55/217), followed by the Koreans (23.65%, 123/520), the Manchus (19.80%, 60/303), and the Hans (15.96%, 128/802). Multiple analysis showed that the gender, consumption of raw/undercooked meat, source of drinking water, residence area, and age were significantly associated with HEV infection in four ethnic groups. The present results indicated that HEV infection was prevalent in Mongols, Koreans, Manchus, and Hans in the surveyed regions, which demonstrated the higher risk of transmitting HEV in multiple nationalities in Eastern and Northeastern China.

Seroprevalence and Risk Factors of Bluetongue Virus Infection in Tibetan Sheep and Yaks in Tibetan Plateau, China.

Bluetongue (BT), caused by bluetongue virus (BTV), is an arthropod-borne viral disease in ruminants. However, information about BTV infection in yaks in China is limited. Moreover, no such data concerning BTV in Tibetan sheep is available. Therefore, 3771 serum samples were collected from 2187 Tibetan sheep and 1584 yaks between April 2013 and March 2014 from Tibetan Plateau, western China, and tested for BTV antibodies using a commercially available ELISA kit. The overall seroprevalence of BTV was 17.34% (654/3771), with 20.3% (443/2187) in Tibetan sheep and 13.3% (211/1584) in yaks. In the Tibetan sheep group, the seroprevalence of BTV in Luqu, Maqu, Tianzhu, and Nyingchi Prefecture was 20.3%, 20.8%, 20.5%, and 19.1%, respectively. The seroprevalence of BTV in different season groups varied from 16.5% to 23.4%. In the yak group, BTV seroprevalence was 12.6%, 15.5%, and 11.0% in Tianzhu, Maqu, and Luqu counties, respectively. The seroprevalence in different seasons was 12.6%, 15.5%, 15.4%, and 9.0% in spring, summer, autumn, and winter, respectively. The season was the major risk factor concerning BTV infection in yaks (P < 0.05). The date of the BTV seroprevalence in Tibetan sheep and yaks provides baseline information for controlling BT in ruminants in western China.

Seroprevalence and risk factors of Toxoplasma gondii infection in stray dogs in northern China.

Toxoplasma gondii is a zoonotic protozoan of almost all species of mammals and birds. However, no information is available about seroprevalence of the pathogen in stray dogs in seven cities from Inner Mongolia, Jilin, Liaoning province, China. Using the indirect hemagglutination antibody (IHA) test with a cutoff titer of 1:64, 129 (14.05 %) out of 918 stray dogs were surveyed to be T. gondii seropositive. Analysis of the risk factor showed that there was no statistical difference of seroprevalence of T. gondii between males (13.46 %) and females (14.54 %) (P > 0.05). The seropositive rates of T. gondii infection in stray dogs among the seven cities in northern China were significant statistically different (P = 0.005). Moreover, seroprevalence of T. gondii in dogs were varied from 11.01 % (95 % CI 6.94-15.09) to 16.86 % (95 % CI 12.27-21.46) among different age groups, and the difference was statistically significant (P = 0.03). More importantly, T. gondii seropositive in stray dogs has a declining tendence from 2011 to 2015 (P = 0.004). The results of the present study showed that stray dogs in Inner Mongolia, Jilin, Liaoning province, China are exposed to T. gondii, for the first time, and could also provide a foundation data for prevent and control T. gondii infection in dogs, other animals and humans.

First report of Toxoplasma gondii seroprevalence in pet parrots in China.

Toxoplasmosis, caused by the obligate intracellular protozoan parasite Toxoplasma gondii, has become a serious public health problem worldwide. T. gondii can infect almost all warm-blooded animals, including parrots. However, little is known of T. gondii infection in parrots in China. Antibodies against T. gondii in 311 parrots including 202 Budgerigars (Melopsittacus undulatus), 26 Lovebirds (Agapornis sp.), 22 Cockatiels (Nymphicus hollandicus), and 61 Alexandrine Parakeets (Psittacula eupatria) in the cities of Beijing and Weifang in north China were tested using the modified agglutination test (MAT). Twenty-six (8.36%) out of 311 serum samples were positive for T. gondii at the cutoff of 1:5. Among the four species, a higher seroprevalence of T. gondii was found in Cockatiels (13.64%, 95% confidence interval [CI] 0.00-27.98), although the difference was not statistically significant (p=0.61). Seropositivity rates against T. gondii in male parrots (10.43%, 95% CI 5.74-15.12) were not statistically different from that in female parrots (6.08%, 95% CI 2.23-9.93, p=0.17). The seropositivity of T. gondii in parrots from Weifang and Beijing was 11.11% (95% CI 6.13-16.09) and 5.70% (95% CI 2.08-9.31), respectively. The seroprevalence varied in parrots of different age groups, ranging from 5.71% (95% CI 1.27-10.15) to 13.00% (95% CI 6.41-19.69), however, the difference among age groups was not statistically significant (p=0.12). The seroprevalence of T. gondii infection in parrots in summer (11.63%, 95% CI 6.84-16.42) was significantly higher than in spring (4.32%, 95% CI 0.94-7.70, p=0.02). The results of the present survey indicated that parrots in China are exposed to T. gondii. To our knowledge, this is the first report of T. gondii seroprevalence in parrots in China.