Lanthanummodified lead titanate(PLT14) ultrafine particles were synthesized by means of stearic acid gel method. The structure of the samples was characterized using Xray diffraction(XRD) and TEM. The crystal graphic ...Lanthanummodified lead titanate(PLT14) ultrafine particles were synthesized by means of stearic acid gel method. The structure of the samples was characterized using Xray diffraction(XRD) and TEM. The crystal graphic parameters of the samples were calculated. The Raman spectra of PLT14 powders at a high pressure as well as a high temperature reveal that the phase transition pressure or temperature shifts to a lower pressure or temperature with the decrease of grain size.展开更多
Background Human bocavirus （HBoV） is a parvovirus recently found to possibly cause respiratory tract disease in children and adults. This study investigated HBoV infection and its clinical characteristics in childre...Background Human bocavirus （HBoV） is a parvovirus recently found to possibly cause respiratory tract disease in children and adults. This study investigated HBoV infection and its clinical characteristics in children younger than five years of age suffering from acute lower respiratory tract infection in Beijing Children＇s Hospital. Methods Nasopharyngeal aspirates were collected from children suffering from acute lower respiratory tract infection during the winters of 2004 to 2006 （from November through the following February）. HBoV was detected by polymerase chain reaction amplification and virus isolation and the amplification products were sequenced for identification. Results HBoV infection was detected in 16 of 333 study subjects. Coinfections with respiratory syncytial virus were detected in 3 of 16 HBoV positive patients with acute lower respiratory tract infection. The median age for HBoV positive children was 8 months （mean age, 17 months; range, 3 to 57 months）. Among the HBoV positive children, 14 were younger than 3 years old, 9 were younger than 1 year old and 7 were younger than 6 months. These 16 positive HBoV children exhibited coughing and abnormal chest radiography findings and more than 60% of these children had wheezing and fever. Ten children were clinically diagnosed with pneumonia, 2 bronchiolitis, 2 acute bronchitis and 2 asthma. One child died. Conclusions HBoV was detected in about 5% of children with acute lower respiratory infection seen in Beijing Children＇s HosPital. Further investigations regarding clinical and epidemiologic characteristics of HBoV infection are needed.展开更多
文摘Lanthanummodified lead titanate(PLT14) ultrafine particles were synthesized by means of stearic acid gel method. The structure of the samples was characterized using Xray diffraction(XRD) and TEM. The crystal graphic parameters of the samples were calculated. The Raman spectra of PLT14 powders at a high pressure as well as a high temperature reveal that the phase transition pressure or temperature shifts to a lower pressure or temperature with the decrease of grain size.
文摘Background Human bocavirus （HBoV） is a parvovirus recently found to possibly cause respiratory tract disease in children and adults. This study investigated HBoV infection and its clinical characteristics in children younger than five years of age suffering from acute lower respiratory tract infection in Beijing Children＇s Hospital. Methods Nasopharyngeal aspirates were collected from children suffering from acute lower respiratory tract infection during the winters of 2004 to 2006 （from November through the following February）. HBoV was detected by polymerase chain reaction amplification and virus isolation and the amplification products were sequenced for identification. Results HBoV infection was detected in 16 of 333 study subjects. Coinfections with respiratory syncytial virus were detected in 3 of 16 HBoV positive patients with acute lower respiratory tract infection. The median age for HBoV positive children was 8 months （mean age, 17 months; range, 3 to 57 months）. Among the HBoV positive children, 14 were younger than 3 years old, 9 were younger than 1 year old and 7 were younger than 6 months. These 16 positive HBoV children exhibited coughing and abnormal chest radiography findings and more than 60% of these children had wheezing and fever. Ten children were clinically diagnosed with pneumonia, 2 bronchiolitis, 2 acute bronchitis and 2 asthma. One child died. Conclusions HBoV was detected in about 5% of children with acute lower respiratory infection seen in Beijing Children＇s HosPital. Further investigations regarding clinical and epidemiologic characteristics of HBoV infection are needed.
