Using mesophase pitch as the raw material, with the rectangular-section spinnerets at different aspect ratios (length divided by width), ribbon-shaped mesophase pitch-based carbon fibers with various ...cross-section sizes and crystal orientations were prepared by adjusting the spinning rate. Effects of the heat-treatment temperature and aspect ratio of spinnerets on structure and properties of the ribbon-shaped carbon fibers were investigated. The results show that the aspect ratio of spinneret and the spinning rate of pitch fibers have a significant influence on the crystal orientation of carbon fibers. Within the specified spinning rate of pitch fibers, the crystal orientation of carbon fibers varies from a parallel-fold structure to a vertical-radial structure with the decrease of the aspect ratio of the spinnerets. The electrical conductivity and the mechanical property of ribbon-shaped carbon fibers significantly increase with the increase of heat-treatment temperature. With increase in spinning rate, ther
Abstract Background Epidemics of acute hemorrhagic conjunctivitis (AHC) caused by a coxsackievirus A24 variant (CA24v) appeared in Taiwan in 2000–2002 and again in 2006–2007. Objective To analyze the ...molecular epidemiology of CA24v in recent outbreaks in Taiwan. Study design A 510 bp fragment of 3Cpro region was analyzed in 30 CA24v isolates during 2000–2007. Phylogenetic tree was constructed along with 130 CA24v isolates available from the GenBank. Moreover, the 235 bp of 3′VP1 region was similarly analyzed in 15 randomly selected strains isolated during 1985–2007. Phylogenetic dendrogram was constructed for the 3′VP1 region in 105 CA24v strains worldwide. Genetic distances were calculated using Kimura 2-parameter model, and phylogenetic trees were constructed by neighbor-joining method. Results The 3Cpro dendrogram depicted genotype IV (GIV), a new genotype that can be further divided into three clusters (C1–C3). The 2000–2002 outbreaks were caused by genotype IV-cluster 1 (GIV-C1) and GIV-C2. Strains isolated in the 2006–2007 outbreak belong to GIV-C3, also in the same cluster as Singapore strains from 2005. Analysis on 3′VP1 revealed only GI, GIII and GIV in line with the classification in 3Cpro dendrogram. All genotype IV strains were also divided into three clusters, though the GIV-C 2′ were isolated from broader geographic areas and over a longer period of time. Conclusions Analysis of the 3Cpro region is more insightful than the 3′VP1 region in the molecular epidemiology of CA24v. The 3Cpro dendrogram accurately and chronologically identified all stains involved in the worldwide outbreaks.
Hafnium carbide ceramic powders were prepared by pyrolysis of a novel precursor, which was synthesized via one pot method using hafnium tetrachloride, acetylacetone, methanol, and hydroquinone as raw ...materials. The composition, morphology and microstructure of the pyrolysis products were characterized by XRD, FTIR, SEM/EDS, TEM, and SAED. The pyrolysis behavior of the obtained Hf C precursor was investigated by TG-DSC and TG-MS. The results show that the ceramization of the Hf C precursor starts at about 600℃, and the formation of Hf C ceramics is initiated at about 1300℃. At temperature above 1500℃, the precursor completely transforms into Hf C ceramics and free carbon. The as-obtained Hf C phase has a single crystal structure and the size of the Hf C particles ranges from 50 to 100 nm. Formation of the Hf C ceramics can be attributed to the carbothermal reduction reaction of the Hf O2, which is produced by pyrolysis of the precursor at a relative low temperature. The growth of the Hf C crystals is retarded
Mesoporous SnO sub(2) was synthesized via a hydrothermal process using tin chloride(SnCl sub(4)middot5H sub(2) O) and urea((NH sub(2)) sub(2) CO) as raw materials, with a block polyether F127(EO ...sub(106)-PO sub(70)-EO sub(106)) as a template. The analysis results(XRD, TEM, BET, etc) show that the amount of F127 has significant influence on pore structure of mesoporous SnO sub(2). With increasing dosage of F127, specific surface area and pore volume of the mesoporous SnO sub(2) increase with pore size distribution relatively broad. The results of the electrochemical tests indicate that existence of mesopores not only provide the path for deinsertion and insertion of Li+, but also buffer the huge volume expansion of tin dioxide, which consequently improves the electrochemical performances of mesoporous SnO sub(2) as an anode material. When the amount of F127 is 6.0 g, the as-prepared 6F-SnO sub(2) with a BET specific surface area of 124 m super(2)/g and average pore size of 4.94 nm, displays optimal cycle per
Despite the availability and use of numerous cholesterol-lowering drugs, atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of mortality globally. Many researchers have focused ...their effort on identifying modified lipoproteins. However, lipid moieties such as lysophosphatidylcholine (LPC) and ceramide (CER) contribute to atherogenic events. LPC and CER both cause endothelial mitochondrial dysfunction, leading to fatty acid and triglyceride (TG) accumulation. In addition, they cause immune cells to differentiate into proinflammatory phenotypes. To uncover alternative therapeutic approaches other than cholesterol- and TG-lowering medications, we conducted untargeted lipidomic investigations to assess the alteration of lipid profiles in apolipoprotein E knockout (apoEsup.−/−) mouse model, with or without feeding a high-fat diet (HFD). Results indicated that, in addition to hypercholesterolemia and hyperlipidemia, LPC levels were two to four times higher in apoEsup.−/− mice compared to wild-type mice in C57BL/6 background, regardless of whether they were 8 or 16 weeks old. Sphingomyelin (SM) and CER were elevated three- to five-fold in apoEsup.−/− mice both at the basal level and after 16 weeks when compared to wild-type mice. After HFD treatment, the difference in CER levels elevated more than ten-fold. Considering the atherogenic properties of LPC and CER, they may also contribute to the early onset of atherosclerosis in apoEsup.−/− mice. In summary, the HFD-fed apoEsup.−/− mouse shows elevated LPC and CER contents and is a suitable model for developing LPC- and CER-lowering therapies.
Adenoviruses account for 5–10 per cent of respiratory illnesses in children. To analyse the clinical features and the temporal frequency in acute adenoviral respiratory infections in hospitalized ...children in southern Taiwan, a total of 4333 children who were admitted to the Department of Pediatrics, Kaohsiung Municipal Hsiaokang (KMHK) Hospital, with clinical evidences of acute respiratory infections between January 2001 and December 2002 were studied. Adenoviruses were isolated from 317 patients with an isolation rate of 7.67 per cent. Serotype analysis was performed by polymerase chain reaction (PCR) and/or PCR-restriction fragment length polymorphism (PCRRFLP) in 186 specimens. In 2001, adenovirus type 4 was found in the majority (57 per cent), followed by type 1.5.6 (15 per cent), type 2 (13 per cent), type 14 (8 per cent), type 3 (5 per cent), and type 7 (2 per cent). In 2002, type 3 became the major type (46 per cent), whereas the previously predominant type 4 decreased to 6 per cent, and type 7 increased from 2 to 19 per cent. The symptoms and signs included fever (98.7 per cent), cough (77.6 per cent), abnormal breathing sounds (crackles and/or wheezing 23.3 per cent), abdominal pain (18.9 per cent), vomiting (21.8 per cent), and diarrhea (25.2 per cent). The mean duration of fever was 4.8 days (range 0–19 days). In the 186 cases in whom serotypes were analysed, pharyngitis and tonsillitis (47.8 per cent) were the most common presentation, followed by pneumonia (25.2 per cent), bronchitis (12.9 per cent), and pharyngoconjunctival fever (PCF) (7.6 per cent). Children between 4 and 8 years old were the most common group of patients with respiratory adenoviral infections. Our patients all had good prognosis. This adenoviruses molecular epidemiological study provides information that helps physicians in clinical differential diagnosis and treatment of respiratory adenoviral infection in children in southern Taiwan.
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