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Leptospirosis is a significant worldwide zoonotic infectious disease that infects a wide range of animals and humans. Leptospira will colonize the animal's urinary and reproductive systems and be excreted with urine, potentially causing a wide range of infections. Dogs are an essential host for Leptospira, and epidemiological investigation studies of leptospirosis must be conducted to clarify the prevalence of leptospirosis and to reduce the risk of transmission to humans. This study aimed to investigate the seroepidemiology of leptospiral infection in dogs from Changchun, China, using Microscopic Agglutination Test (MAT). A total of 1053 canine blood samples were collected and tested by MAT. The positive rate of MAT was approximately 19.1%. The main prevalent Leptospira serogroups were L. Icterohaemorrhagiae (8.1%), L. Canicola (7.6%), L. Australis (5.3%), L. Ballum (4.7%) and L. Pyrogenes (4.2%). No statistically significant difference among different varieties, sexes and sampling seasons (p > 0.05), except the age (p < 0.05). The seropositive rate was much higher in adult and aged dogs than in juvenile dogs. Our results showed the seroprevalence and the prevalent serogroup of Canine leptospirosis in Changchun, China. [ABSTRACT FROM AUTHOR]

Printed Circuit Heat Exchanger (PCHE) with high-efficiency and compact structure has great application prospect in the supercritical carbon dioxide (S-CO2) power systems for the next generation of high-temperature concentrated solar and advanced nuclear energy. However, the high operating temperature and pressure require PCHE to maintain good heat transfer performance, as well as reliable mechanical performance at the same time. It is necessary to carry out the fluid-thermal-mechanical coupled analysis of PCHE for the safe and efficient operation of the S-CO2 cycle. In this paper, a three-dimensional fluid-structure coupled numerical model was established to study the fluid-thermal-mechanical coupled characteristics of PCHE under different airfoil fin arrangements. The stress distribution of the single airfoil fin was studied, and a better airfoil arrangement that comprehensively considers heat transfer characteristics and stress distribution was obtained. Aiming at the high stress caused by the stress concentration at both ends of the airfoil fin, an optimized configuration combining straight channel and airfoil channel was proposed. The results show that the difference between the flow and heat transfer performance of the two optimized structures and the reference structure is only within 1.5%, but the maximum stresses of the two optimized structures are respectively reduced by 69.4% and 70.0% compared with that of the reference structure, which significantly reduces the stress intensity of PCHE. The result provides a new method to develop the airfoil PCHE with uniform stress distribution and good thermo-hydraulic performance. [ABSTRACT FROM AUTHOR]

The laser flash method is commonly adopted to measure the thermal diffusivity of solid material since its advantages, such as a wide measuring range of thermal di ITusivity.a small amount of samples, a high measuring temperature, and so on. However, the sample holders used by this method are limited and costly, which seriously affects the convenience and economy of this method. So. in order to develop and design more kinds of sample holders. it is necessary to study the effects of sample holder characteristics on measurins results. A transient flow and heat transfercalculatim model was developed to analyse effects of pulse energy, pulse tiine, laser beam area. protective gas flow and sample holder materials on the thermal diffusivity measurement. It is found that the temperature increase of the sample upper surface AT obviously increases with pulse energy, pulse time and laser beam area increasing, but the half heating up time tio slightly decreases with theses parameters increasing.AT and t„ are independent to tlie volume flow rate of protective gas. The heat transfer process and mechanism between sample and holders with various materials were analysed. The heat loss of samples depends on the heat conduction and radiation between sample and holder, the heat convection and radianon from sample to protective gas. The theriii:~1 conductivity, speci fic heat and emissivity 01 holder materials can affect the heat conduction and radiat ion between sample and holder slightly. So the AT and 4, are nearly independent to the holder material properties. Based on these conclusions, a new SUS310 holder was made, and the thermal diffusivity of a sample was experimentally measured using the new holder. As a result, the measuring error is less than +3%. [ABSTRACT FROM AUTHOR]