ABSTRACT
The interaction between polysulfone and ZrO(2) particles is studied as a function of the particle sintering temperature in order to understand the role of ZrO(2) on the formation, morphology, and properties of organo-mineral composite membranes. The adsorption between the sintered ZrO(2) and the constituents of polysulfone, 2,2-diphenylpropane and diphenyl sulfone, is investigated using high-pressure liquid chromatography. The influence of the polymer-ZrO(2) interaction on the flow behavior of the casting suspension is registered via viscoelastic measurements. The organo-mineral composite membranes are formed by immersion precipitation in water, and the resulting membrane morphology is analyzed using high-resolution SEM. The zirconia concentration in the top-layer of the composite structure is determined by XPS. Finally, the link between the polymer-filler interactions, the membrane formation process, and the resulting membrane structure and properties is established.
Subject(s)
Polymers/chemistry , Sulfones/chemistry , Zirconium/chemistry , Adsorption , Dapsone/chemistry , Membranes, Artificial , Permeability , Porosity , Spectrum Analysis , Suspensions , Temperature , X-RaysABSTRACT
Properties of the echinoderm skeleton are under biological control, which is exerted in part by the organic matrix embedded in the mineralized part of the skeleton. This organic matrix consists of proteins and glycoproteins whose carbohydrate component is specifically involved in the control mechanisms. The saccharide moiety of the organic matrix of the spines of the echinoid Paracentrotus lividus was characterized using enzyme-linked lectin assays (ELLAs). O-glycoproteins, different types of complex N-glycoproteins, and terminal sialic acids were detected. Sialic acids are known to interact with Ca ions and could play an important role in the mineralization process. Some of the carbohydrate components detected by ELLAs as well as two organic matrix proteins (SM30 and SM50) were localized within different subregions of the spine skeleton using field-emission scanning electron microscopy. The mappings show that some of these components are not homogeneously distributed in the different skeletal subregions. For example, some N-glycoproteins were preferentially located in the putative amorphous subregion of the skeleton, whereas some O-glycoproteins were localized in the subregion where skeletal growth is inhibited. These results suggest that the biological control exerted on the skeletal properties can be partly modulated by local differences in the organic matrix composition.
Subject(s)
Carbohydrates/analysis , Extracellular Matrix/chemistry , Proteins/analysis , Sea Urchins/anatomy & histology , Animals , Calcification, Physiologic , Cytoskeletal Proteins/analysis , Enzyme-Linked Immunosorbent Assay/methods , Extracellular Matrix Proteins/analysis , Lectins , Microscopy, Electron , Polysaccharides/analysis , Sea Urchins/chemistry , Sialic Acids/analysisABSTRACT
A 2-day-old neonate was admitted to hospital with septicaemia and meningitis found to be caused by Plesiomonas shigelloides. In spite of a course of intravenous ampicillin and cefotaxime he died 2 days later. We could not isolate the bacterium from the faeces of the mother and her dog, nor from the aquarium-water of her parents-in-law nor from the aquarium-water and fish of the doctor who delivered the baby. We briefly review the literature on P. shigelloides meningitis and its epidemiology.
