RESUMEN
With the higher requirements of various tactical and technical indicators of the weapon systems, the current research on the ignition and combustion characteristics of different types of solid propellants is not comprehensive. In more complex and harsh environmental conditions, the pressure affects the ignition and combustion characteristics. Therefore, the paper studies the ignition and combustion characteristics of the modified double-base propellants (MDB propellants) and fuel-rich propellants (FR propellants) under low-pressure environment. Combining experiment and theory, the ignition delay time and burning rate of two kinds of solid propellants are compared and analyzed at low pressure by the laser ignition experimental device. The results displayed that the burning flames of the FR and MDB propellant presented evident V-shape and cylindrical, respectively. The flame brightness decreased with the decrease in pressure. With the increase of pressure and heat flux, the ignition delay time of the MDB propellant and the FR propellant decreased. By comparison, Model 2 of the ignition delay time was more effective for the estimation of the ignition delay time of the FR propellant. The experimental results are compared with the three burning rate models, which are the Vielle formula (Model 1), Summerfield formula (Model 2), and B-number burning rate formula (Model 3). The results showed the burning rate was more in accord with Model 3.
RESUMEN
Myelodysplastic syndrome (MDS) consists of a group of hematologic tumors that are derived from the clonal proliferation of hematopoietic stem cells, featuring abnormal hematopoietic cell development and ineffective hematopoiesis. Animal models are an important scientific research platform that has been widely applied in the research of human diseases, especially tumors. Animal models with MDS can simulate characteristic human genetic variations and tumor phenotypes. They also provide a reliable platform for the exploration of the pathogenesis and diagnostic markers of MDS as well as for a drug efficacy evaluation. This paper reviews the research status of three animal models and a new spontaneous mouse model with MDS.
Asunto(s)
Neoplasias Hematológicas , Síndromes Mielodisplásicos , Animales , Ratones , Humanos , Síndromes Mielodisplásicos/genética , Células Madre Hematopoyéticas/patología , Modelos Animales de Enfermedad , HematopoyesisRESUMEN
Guillain-Barre Syndrome (GBS) is a neuromuscular disorder and campylobacteriosis is known to trigger the onset of the disorder. A polymerase chain reaction (PCR) protocol was developed that could specifically amplify a 497-bp region of the UDP-galactose 4-epimerase (galE) gene sequence in campylobacters responsible for triggering the onset of GBS. The identity of the PCR product was confirmed by Hind III endonuclease restriction digestion, which produced the predicted 430 and 67-bp DNA fragments. The assay could detect the presence of the gene in Campylobacter suspensions containing as few as 5 cells ml(-1). The assay detected the presence of the gene in 17 of the 20 campylobacters isolated from chicken, 9 of the 13 campylobacters isolated from turkey and 7 of the 7 campylobacters isolated from human stools. All Campylobacter strains isolated from chicken, turkey and clinical samples were resistant to multiple antibiotics. The assay failed to detect the presence of the gene in five different microaerophilic strains of Helicobacter spp., E. coli and Salmonella spp. The entire diagnostic assay, including template preparation, amplification and electrophoresis, can be completed within 6 h.