No abstract

PMMA/Na-MMT nanocomposites were synthesized through a soap-free emulsion polymerization of methyl methacrylate (MMA) using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). A conventional anionic surfactant, dodecylbenzenesulfonic acid sodium salt (DBS-Na), was also used to compare with AMPS in the interaction with pristine Na-MMT. Both surfactants were intercalated into the layers of the pristine Na-MMT dispersed in water before polymerization. The nanocomposites with AMPS were exfoliated during polymerization because AMPS made the polymer end-tethered on pristine Na-MMT. The nanocomposites were exfoliated up to the 10 wt % content of pristine Na-MMT relative to the amount of MMA. The molecular weight of PMMA obtained from the nanocomposite with AMPS decreased, and the glass transition temperature (T g) and storage modulus (E‘) of the nanocomposites became higher as the amount of Na-MMT increased.

No abstract

Soil-transmitted helminths (STH), namely Ascaris, Trichuris and hookworms (Ancylostoma and Necator), present a global health problem to about a half of the earthos population. In the Republic of Korea, STH were highly prevalent and were considered a high priority target for national control. To promote the control, a non-governmental organization named Korea Association for Parasite Eradication (currently Korea Association of Health Promotion) was founded in 1964, and mass fecal examination followed by selective mass chemotherapy with anthelmintics was performed twice a year from 1969 to 1995 targeting whole nationwide schoolchildren. Meanwhile, decreasing patterns of national STH infections have been monitored by 7 timeso quinquennial national surveys targeting general population. In 1971, the overall intestinal helminth egg positive rate was 84.3% (Ascaris 58.2%, Trichuris 65.4%, and hookworms 10.7%), which became 63.2% in 1976, 41.1% in 1981, 12.9% in 1986, 3.8% in 1992, 2.4% in 1997, and 4.3% (Ascaris 0.03%, Trichuris 0.02%, and hookworms 0%) in 2004. During the control period, national economy rapidly developed, and living standards including environment, sanitation, and agricultural technology greatly improved, which undoubtedly boosted the STH control effects. Our experience indicates that social driving force to establish an eligible national control system to conduct repeated mass chemotherapy, together with improvement of environment and sanitation, is important for initiating and achieving STH control in a developing community.

The melt intercalation and curing behavior of phenolic resin (P1) were investigated by use of layered silicates, such as pristine montmorillonite (PM), dodecylammonium-modified montmorillonite (C12M), octadecylammonium-modified montmorillonite (C18M), benzyldimethyloctadecylammonium-modified fluorohectorite (C18BH), and hexamethylenetetramine (HMTA), as curing agents. It was found by X-ray diffraction that the uncured phenolic resin was intercalated into PM, C18M, and C18BH. Cured phenolic resin-layered silicate nanocomposites were prepared by two methods:  one was the sequential process of intercalation and curing (IC, the suffix of sample code), and the other was the simultaneous process of mixing and curing (MC). The intercalated structures were preserved in cured P1C18BH but not in cured P1C18M, i.e., the phenolic resin intercalated in C18M was deintercalated when it was cured. It was suggested that the intercalated structure of P1C18BH was more stable in the curing process than that of P1C18M due to chemical affinity derived from the favorable interaction between the phenolic resin and intercalant-containing benzene ring. Transmission electron micrographs showed that a splitted-stacked structure was formed in the samples of P1PMMC and P1PMIC, indicating the phenolic resin did not intercalate the PM. Conclusively, the modification of layered silicate and the resulting interaction between organic modifier and phenolic resin played an important role in determining the stable nanostructure and the final morphology of phenolic resin-layered silicate nanocomposite.

Toxocariasis is a worldwide zoonosis caused by larvae of ascarid nematodes of dogs or cats, Toxocara canis or T. cati. Diagnosis of human toxocariasis currently relies on serology that uses T. canis excretory-secretory antigen to detect specific IgG antibodies by ELISA. We investigated the serodiagnostic efficacy of ELISA using crude antigen of T. canis larvae (TCLA). Serum specimens of 64 clinically confirmed toxocariasis, 115 healthy controls, and 119 other tissue-invading helminthiases were screened by ELISA using TCLA. The ELISA using TCLA showed 92.2% (59/64 patient samples) sensitivity and 86.6% (103/119) specificity. Its positive diagnostic predictivity was 78.7% and negative predictivity was 97.8%. No serum of healthy controls reacted but that of anisakiasis (45.5%), gnathostomiasis (19.2%), clonorchiasis (15.8%), sparganosis (11.1%), and cysticercosis (6.3%) cross-reacted. Immunoblot analysis on TCLA recognized antigenic proteins of 28- and 30-kDa bands in their dominant protein quantity and strong blotting reactivity. The present results indicate that the ELISA using our TCLA antigen is acceptable by the sensitivity and specificity for serodiagnosis of human toxocariasis. ELISA with TCLA is recommended to make differential diagnosis for patients with any sign of organ infiltration and eosinophilia.

Abstract:Although stool examination is the standard diagnostic method of clonorchiasis, serodiagnosis by ELISA using crude antigen is now widely used because of its convenience. However, ELISA diagnosis still suffers from cross-reactions, and therefore there is a need to improve the present conventional ELISA. The present study was undertaken to evaluate the diagnostic value of ELISA using excretory-secretory antigen (ESA) instead of crude antigen (CA) of Clonorchis sinensis. The diagnostic sensitivity of ELISA using excretory-secretory antigen was 92.5%, which was higher than that of ELISA using crude Clonorchis sinensis antigen (88.2%). In addition, the specificity of excretory-secretory antigen was found 93.1% while that of crude antigen was 87.8%. In summary, Clonorchis sinensis ESA was found to be a better serodiagnostic antigen than CA for ELISA.

No abstract