Submicron particles larger than about 0.1m in pond and river waters were collected on a carbon film mounted on a specimen grid by centrifugation and then studied morphologically and analyzed for major elements heavier than sodium, with a high-resolution transmission electron microscope equipped with an energy dispersive X-ray analyzer. If available, the data were compared with those of particles artificially prepared under various conditions. Four typical particles—aluminosilicate, quartz, fine-particle aggregates containing silica and iron(III) oxide, and microorganisms—were found in fresh waters. 相似文献
The de-excitation rate constants of Ne(3P2, 3P0 and 3P1) by N2 and SF6 were measured using a pulse radiolysis method combined with optical absorption spectroscopy. A new absorption law which relates the relative concentration S of absorbing atoms to the measured transmittance T, i.e. in S = Σ11i = 0aiTi, was used for analyzing the data. The presence of a small amount of SF6 in the sample gas mixtures permitted removal of some artifacts due to thermal electrons for determining the rate constants. 相似文献
Recall that a projective curve in with ideal sheaf is said to be n-regular if for every integer and that in this case, it is cut out scheme-theoretically by equations of degree at most n. The purpose here is to show that an irreducible, reduced, projective curve of degree d and large arithmetic genus satisfies a smaller regularity bound than the optimal one . For example, if then a curve is -regular unless it is embedded by a complete linear system of degree .
Received: 29 May 2000 / Published online: 24 September 2001 相似文献
Copper at the low or fractional ng g?1 level in 0.1 M oxalic acid solutions at pH 1.6 is electrodeposited on a chemically-modified glassy carbon electrode with surface-bound groups at ?0.6 V vs. Ag/AgCl (3.3 M KCl). The deposit is then anodically stripped in the same solution, a current-potential curve being recorded by the differential-pulse technique. The advantages of this electrode over an unmodified glassy carbon electrode include higher sensitivity, precision and selectivity; the modified electrode can be used 50–100 times without further treatment. 相似文献
The behavior of self‐assembly processes of nanoscale particles on plasma membranes can reveal mechanisms of important biofunctions and/or intractable diseases. Self‐assembly of citrate‐coated gold nanoparticles (cAuNPs) on liposomes was investigated. The adsorbed cAuNPs were initially fixed on the liposome surfaces and did not self‐assemble below the phospholipid phase transition temperature (Tm). In contrast, anisotropic cAuNP self‐assembly was observed upon heating of the composite above the Tm, where the phospholipids became fluid. The number of self‐assembled NPs is conveniently controlled by the initial mixing ratio of cAuNPs and liposomes. Gold nanoparticle protecting agents strongly affected the self‐assembly process on the fluidic membrane. 相似文献