A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles

Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm) using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles

Physiology of sulfate transport by the crustacean hepatopancreas

Thesis (Ph. D.)--University of Hawaii at Manoa, 1993.Microfiche.xi, 123 leaves, bound 29 cmThe hepatopancreas, or digestive gland, of Homarus americanus (and other crustaceans), has been shown to playa major role in the digestion and absorption of nutrients. Although the hepatopancreas has been implicated in the manufacture and release of digestive enzymes there have been no reports of its ability to secrete other solutes such as ions. The organ has been suggested as a possible site of excretion due to its cellular morphology and direct access to the lumen of the digestive tract. It has been demonstrated that sulfate is present in lobster hemolymph at a concentration lower than in seawater. The present investigation utilized isolated membrane vesicles to determine the mechanisms and characteristics of sulfate transport across both the apical and basolateral membranes of the hepatopancreas. The brush border membrane of the hepatopancreatic epithelium appears to contain a transport protein which translocates cytoplasmic sulfate in exchange for luminal chloride. This antiport mechanism operates in an electrogenic fashion by exchanging one sulfate for one chloride, resulting in the movement of a net negative charge out of the epithelial cell. There was no indication of sodium-sulfate cotransport commonly reported for the brush border membrane of vertebrate renal and intestinal epithelia. It was found that the antiporter was stimulated by the presence of a high concentration of luminal protons. This suggested that the sulfate antiporter was regulated by the brush border sodium-proton exchanger which acidifies the hepatopancreas lumen. Sulfate was found to exchange for the dicarboxylic anion oxalate by an electroneutral antiporter in the hepatopancreatic basolateral membrane. This transporter would allow for movement of sulfate from the hemolymph, which bathes the hepatopancreas, to the cytoplasm of the epithelium. The serosal antiporter did not show a response to manipulation of proton concentrations. A model of transcellular sulfate secretion by the hepatopancreatic epithelium has been proposed utilizing the two antiporters working in sequence to bring about vectorial sulfate movement. This is the first experimental evidence which implicates the crustacean hepatopancreas as a secretory organ

A constraint language in C

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1983.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERINGBibliography: leaves 76-77.by William D. Cattey.B.S

s-Block metal scorpionates – A new sodium hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate salt showing an unusual core stabilized by bridging and terminal O-bonded DMSO ligands

International audiences-Block metal scorpionates-A new sodium hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate salt showing an unusual core stabilized by bridging and terminal O-bonded DMSO ligands https://doi. Abstract: Dissolution of [(μ-Me 2 CO) 3 (NaTp *) 2 ] (1) (Tp* = hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate) in DMSO at room temperature leads to the growth of colourless crystals characterized as the new salt [Na 2 Tp * (μ-Me 2 SO) 3 (Me 2 SO) 3 ] [NaTp * 2 ] (2). 2 crystallized in the trigonal space group R3 with Z = 3, a = 14.1227(2) Å, b = 14.1227(10) Å, c = 33.9685(2) Å, and V = 5867.35(17) Å 3. Interestingly, anion and cation of 2 both contain the Tp* ligand. Moreover, the cationic moiety highlights an unusual sodium atom hexacoordi-nated by six DMSO molecules acting as O-bonded ligands. Three of which exhibit a bridging coordination mode and three are in terminal position. To the best of our knowledge , the framework of [Na 2 Tp * (μ-Me 2 SO) 3 (Me 2 SO) 3 ] is unprecedented

Structural characterization of 2,2-di-n-butyl-4-methyl-1,3,2-dioxastannolane isolated from supercritical CO₂ conditions

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