Lanthanide, 294 particles

Silica is an alternative host for lanthanide chelates. Synthesis of nanosized silica particles by well-estabhshed hydrolysis of tetraethylorthosihcate (TEOS) with ammonium hydroxide is a common route for particle preparation. The transparent inert silica material is an excellent matrix for dye-embedded nanolabels as less spectral interferences are expected from the host material. Multiple lanthanide particles have been prepared for bioanalysis. Nanoparticles have been S3Uithesized by hydrolysis of TEOS with ammonium hydroxide in a microemulsion-containing aqueous solution of N,iV,iV, N -[2,6-bis(3 -aminomethyl-l -pyrazolyl)-phenylpyri-dine]tetrakis(acetate)-Tb(in) (BPTA-Tb ) chelate. In the microemulsion, the aqueous phase containing the lanthanide chelate formed nanodroplets acting as nanoreactors for the synthesis of nanoparticles. Since the size of the nanoparticles is dependent on the size of the droplets, it can be controlled, e.g., by the t3q>e of surfactants and by adjusting the concentration of the reactants [42-46],... 

Neutron-rich lanthanide isotopes occur in the fission of uranium or plutonium and ate separated during the reprocessing of nuclear fuel wastes (see Nuclearreactors). Lanthanide isotopes can be produced by neutron bombardment, by radioactive decay of neighboring atoms, and by nuclear reactions in accelerators where the rate earths ate bombarded with charged particles. The rare-earth content of solid samples can be determined by neutron... 

The minerals on which the work was performed during the nineteenth century were indeed rare, and the materials isolated were of no interest outside the laboratory. By 1891, however, the Austrian chemist C. A. von Welsbach had perfected the thoria gas mantle to improve the low luminosity of the coal-gas flames then used for lighting. Woven cotton or artificial silk of the required shape was soaked in an aqueous solution of the nitrates of appropriate metals and the fibre then burned off and the nitrates converted to oxides. A mixture of 99% ThOz and 1% CeOz was used and has not since been bettered. CeOz catalyses the combustion of the gas and apparently, because of the poor thermal conductivity of the ThOz, particles of CeOz become hotter and so brighter than would otherwise be possible. The commercial success of the gas mantle was immense and produced a worldwide search for thorium. Its major ore is monazite, which rarely contains more than 12% ThOz but about 45% LnzOz. Not only did the search reveal that thorium, and hence the lanthanides, are more plentiful than had previously been thought, but the extraction of the thorium produced large amounts of lanthanides for which there was at first little use. 

Analysis of the lanthanide-induced crystalline arrays by negative staining (Fig. 5) or freeze-fracture electron microscopy reveals obliquely oriented rows of particles, corresponding to individual Ca -ATPase molecules [119]. The unit cell dimensions for the gadolinium-induced Ca -ATPase crystals are a = 6. l A, b = 54.4 A and y = 111°. Similar cell constants were obtained for the crystals induced by lanthanum, praseodymium and calcium. The unit cell dimensions of the Ei crystals are consistent with a single Ca -ATPase monomer per unit cell. The space group of the Eptype crystals is PI [119], while that of the E2 crystals is P2 [88,90]. 

Glenn Theodore Seaborg (1912-1999), together with Stanley Gerald Thompson (1912-1967) and Albert Ghiorso ( 1915). The bombardment of americium-241 with alpha particles led to element 97 with atomic mass number 243. The enrichment involved chemical methods, as the properties of the element were assumed to be analogous to those of the lanthanides. 

Differentiating lanthanide-labeled particles from rhodamine-labeled particles by luminescence... 

Figure 19 Differentiation of lanthanide-labeled particles by lifetime mapping.

Clearance to pulmonary lymph nodes will occur at a fractional rate of 0.0001 per day. Dissolution of the deposited particles and absorption of cerium into the systemic circulation will occur at rates that are between the extremes represented by CeCh in CsCl particles and Ce oxide or Ce in fused aluminosilicate particles as given by the functions included in Figure 9. These rates should not be expected to be constant over the entire clearance period and will depend upon the overall composition of the bulk aerosol particles, which indude particle size, amount of stable lanthanide present, acidity, and the solubility of other components of the particles. The accuracy of predicting respiratory tract clearance and internal organ uptake of radiocerium will depend heavily upon adequate determination of the particle solubility characteristics. 

The local structure around the lanthanide ions with differing redox potentials Eu(III)/(II) (-0.35 V vs. NHE), Yb(III)/(II) (-1.05 V), and Sm(III)/(II) (-1.55 V) in Ti02 particles was investigated by EXAFS. The photocatalytic reaction and EXAFS studies were also carried out for a calcined Yb(III) ion adsorbed-Ti02 catalyst [157], The photocatalytic activity of these lanthanides toward methyl blue photodecomposition was very similar, suggesting that adsorbed lanthanide ions on TiOz particles scarcely assist the high-photocatalytic activity of TiOz catalyst. However, the way in which the catalysts were activated was of high importance. The photocatalytic activity of the calcined Yb/TiOz... 

As noted in table 11.1, the ability of THFTCA to separate LJO from trivalent lanthanide ions is mainly of enthalpic origin. Reaction 11.33 has a considerably more unfavorable enthalpic contribution than reaction 11.32. The complexation is, however, predominantly entropy driven because the T ArS° term dominates the ArH° contribution for all systems. The large positive entropy changes observed for reactions 11.32 and 11.33 result from the release of water molecules coordinated to the metal on complexation with the tridentate THFTCA2- ligand. Note that a negative entropy contribution would be expected if these reactions were truly 2 particle = 1 particle reactions [226]. 

Berkelium is a metallic element located in group 11 (IB) of the transuranic subseries of the actinide series. Berkelium is located just below the rare-earth metal terbium in the lanthanide series of the periodic table. Therefore, it has many chemical and physical properties similar to terbium ( Tb). Its isotopes are very reactive and are not found in nature. Only small amounts have been artificially produced in particle accelerators and by alpha and beta decay. 

Californium is a transuranic element of the actinide series that is homologous with dysprosium (gjDy), just above it in the rare-earth lanthanide series. Cf-245 was the first isotope of californium that was artificially produced. It has a half-life of just 44 minutes. Isotopes of californium are made by subjecting berkelium to high-energy neutrons within nuclear reactors, as follows + (neutrons and A, gamma rays) — °Bk — °Cf + (3- (beta particle... 

Narrow bands arise when the overlap of the atomic wave functions is small (as for 5 f s). In this case, the dispersion E(k) is strongly reduced and the bandwidth W becomes very small (zero, in the case of no overlap). The electron charge density, caused by these wave functions, is high in the core region of Fig. 12, and the quasi-particles spend most of their life there, nearly bound to the atom. In case the charge density is all confined within the core region (as for 4f in lanthanides), then the bond description loses its meaning and the atomic description holds. 

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