Studies on monodispersed colloidal particles of doped yttrium compounds

Monodispersed particles of doped yttrium basic carbonates were prepared at aging at elevated temperature corresponding salts solutions in the presence of urea. Coprecipitation in mixed solutions of yttrium, lanthanum and neodymium salts under similar experimental conditions yielded composite particles of basic carbonates. The content of the three metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so-prepared powders were characterized by various techniques.

Photoluminescence of ZnS Clusters in Zeolite-Y

Two obvious emissions are observed from the ZnS clusters encapsulated in zeolite-Y. The emission around 355 nm is sharp and weak, locating at the onset of the absorption edge. The band around 535 nm is broad, strong and Stokes-shifted. Both the two emissions shift to blue and their intensities firstly increase then decrease as the loading of ZnS in zeolite-Y or clusters size decreases. Through investigation, the former is attributed to the excitonic fluorescence, and the latter to the trapped luminescence from surface states. The cluster size-dependence of the luminescence may be explained qualitatively by considering both the carrier recombination and the nonradiative recombination rates. Four peaks appearing in the excitation spectra are assigned to the transitions of 1S-1S, 1S-1P, 1S-1D and surface state, respectively. The excitation spectra of the clusters do not coincide with their absorption spectra. The states splitted by quantum-size confinement are detected in the excitation spectra, but could not be differentiated in the optical absorption spectra due to inhomogeneous broadening. The size-dependence of the excitation spectra is similar to that of the absorption spectra. Both the excitation spectra of excitonic and of trapped emissions are similar, but change in relative intensity and shift in position are observed.

SYNERGIC EFFECT OF POLYMER SUPPORTED Pd－Pt BIMETALLIC CATALYSTS ON THE HYDROGENATION OF NITROAROMATICS

s: Hydrogenation of nitroaromatics has been carried out under mild conditions using poly-N-vinyl-2-pyrrolidone supported Pd-Pt bimetallic catalysts (PdCl2 and H2PtCl6 as catalyst precursors).The catalytic activities of the bimetallic catalysts are significantly higher than those of themonometallic Pd or Pt catalyst especially in the case of the hydrogenation of substitutednitroaromatics due to a remarkable synergic effect. The ratio of Pd to Pt in the catalyst influences theactivity of the catalyst.

Carbonylation of Allyl Chloride Catalyzed by PdCl_2（TPPTS）_2 in Two－phase Medium

PdCl2(TPPTS)2 exhibits very high catalytic activity for carbonylation of allyl chloride in aq. NaOH / toluene two-phase medium under atmospheric pressure.The average turnover frequency (TOFav,mol substrate / mol Pd·min) reaches 31 min(-1).

PREPARATION OF DI－GRIGNARD REAGENTS MEDIATED BY THE TRANSITION METAL CHLORIDES

In the presence of transition metal chloride and potassium iodide, di-Grignard reagents can be produced efficiently by the reactions of aryl dichlorides with active magnesium species, which are formed in situ from commercial magnesium powder activated by a small amount of anthracene.

CYCLOTRIMERIZATION OF NITRILES BY THE REACTIVE ALKALI METAL HYDRIDES

In the presence of reactive alkali metal hydrides, nitriles can be cyclotrimerized to give 2,4,6-trisubstituted-1,3,5-triazines and 2,4,6-trisubstituted imidazoles in moderate yield.

HYDROGENOLYSIS OF ARYL HALIDES WITH POWDERS OF ALKALI METAL HYDRIDES OF NANOMETRIC SIZE

Superfine powders of alkali metal hydrides of nanometric size exhibit very high reactivity in the hydrogenolysis of aryl halides.

Syntax of first-order lattice valued logic system FM

PAVELKA in ref. [1] established a propositional logic system whose truth values domain is an enriched residuated lattice and obtained some beautiful results. In order to study more general lattice valued logic systems, we proposed the concept of lattice implication algebra, discussed the corresponding lattice valued propositional logic system, and established a

Studies on the energy transfer system of terbium-norfloxacin chelate and its interaction with serum albumins

The energy absorbed by norfloxacin could be transferred to terbium(III) through chelation of norfloxacin with terbium(III), then the characteristic fluorescence emission could be observed. The interaction of serum albumins with norfloxacin have been investigated in this paper. The results showed that HSA could inhibit the energy transfer between norfloxacin and terbium(III). But, BSA could not. It was shown that the binding properties of norfloxacin to HSA and BSA were totally different.

An effective method for the hydrodehalogenation of organic halides

THE reduction of organic halides to the corresponding hydrocarbons plays an important role inorganic synthesis and environmental decontamination.It is one of the earliest reactions de-scribed in the organic chemical literature.A number of successful approaches have been report-ed hitherto,but the hydrodehalogenation of chloroarenes and organic fluorides is still a

Filters and structure of lattice implication algebra

IN order to research the logical system whose propositional value is given in a lattice from