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In the present paper, the basic radiation parameters of tellurite glasses with different forming oxides ([B.sub.2][O.sub.3], BaO, [K.sub.2]O, [V.sub.2][O.sub.5], W[O.sub.3], and ZnO) have been studied over a wide photon energy range from 1 keV to 100 GeV, using WinXCom program. These parameters are the mass attenuation coefficient (μ/ρ), effective atomic number ([Z.sub.eff]), and electron density ([N.sub.e,eff]). In addition, the macroscopic effective removal cross sections (2R) for fast neutrons have been calculated. The dependence of different parameters on incident photon energy and chemical content has been discussed. Among the selected glass systems Te[O.sub.2]-W[O.sub.3] and Te[O.sub.2][B.sub.2][O.sub.3] showed superior shielding properties for gamma-ray and neutrons, respectively. It is shown that the selected glass systems have higher values of the mass attenuation coefficients (μ/ρ) than concretes and 0.7Si[O.sub.2]:0.3BaO glass. These results indicate that tellurite glasses can be used as radiation shielding materials. Key words: tellurite glasses, gamma-ray, mass attenuation coefficient, effective atomic number, radiation shielding. Nous utilisons ici le programme WinXCom pour etudier, sur un domaine d'energie des photons de 1 keV a 100 GeV, les parametres de radiation de base de verres de tellurite avec differents oxydes ([B.sub.2][O.sub.3], BaO, [K.sub.2]O, [V.sub.2][O.sub.5], W[O.sub.3] et ZnO). Ces parametres sont le coefficient d'attenuation massique (μ/ρ), le nombre atomique effectif (Zefr) et la densite d'electrons (Ne eff). Nous calculons aussi les sections efficaces de retrait effectif macroscopique des neutrons rapides (2R). Nous discutons la dependance des differents parametres sur l'energie des photons et le contenu chimique. Parmi les verres etudies, Te[O.sub.2]-W[O.sub.3] et Te[O.sub.2]-[B.sub.2][O.sub.3] montrent le meilleur blindage contre les rayons y et les neutrons respectivement. Les resultats montrent que les verres selectionnes ont de plus hautes valeurs du coefficient d'attenuation massique (^/p) que le beton et le verre 0.7Si[O.sub.2]: 0.3BaO. Ces resultats montrent donc que les verres de tellurite peuvent etre utilises comme blindage contre les radiations. [Traduit par la Redaction] Mots-cles: verres de tellurite, rayon y, coefficient d'attenuation massique, nombre atomique effectif, blindage contre les radiations., 1. Introduction Nowadays, nuclear radiation is increasingly being used in various fields, such as medical, agriculture, and scientific research and other scientific and technological fields, so it is important to [...]

We have analyzed peptides, proteins, and protein--drug complexes through surface-assisted laser desorption/ ionization mass spectrometry (SALDI-MS) using HgTe nanostructures as matrixes. We investigated the effects of several parameters, including the concentration of the HgTe nanostructures, the pH of the buffer, and the concentration of salt, on the performance of this system. When HgTe nanostructures are used as matrixes, [[M + H].sup.+] ions were the dominant signals. Relative to other commonly used nanomaterials, HgTe nanostructures provided lower background signals from metal clusters, fewer fragment ions, less interference from alkali-adducted analyte ions, and a higher mass range (up to 150 000 Da). The present approach provides limits of detection for angiotensin I and bovine serum albumin of 200 pM and 14 nM, respectively, with great reproducibility (RSD: 10.1021/ac100550c

Xocolatlite, [Ca.sub.2][Mn.sup.4+.sub.2][Te.sup.6+.sub.2][O.sub.12] x [H.sub.2]O, is a rare new mineral from the Moctezuma deposit in Sonora, Mexico. It occurs as chocolate-brown crystalline crusts on a quartz matrix. Xocolatlite has a copper-brown streak, vitreous luster, and is transparent. Individual crystals show a micaceous habit. Refractive indices were found to be higher than 2.0. Density calculated from the empirical formula is 4.97 g/[cm.sup.3], and immersion in Clerici solution indicated a density higher than 4.1 g/[cm.sup.3]. The mineral is named after the word used by the Aztecs for chocolate, in reference to its brown color and provenance. The crystallographic characteristics of this monoclinic mineral are space group P2, P2/m, or Pro, with the following unit-cell parameters refined from synchrotron X-ray powder diffraction data: a = 10.757(3) [Angstrom], b = 4.928(3) [Angstrom], c = 8.942(2) [Angstrom], [beta] = 102.39(3)[omicron], V = 463.0(3) [[Angstrom].sup.3], and Z = 2. The unavailability of a suitable crystal prevented single-crystal X-ray studies. The strongest 10 lines of the X-ray powder diffraction pattern are [d in [Angstrom] (I) (hkl)]: 3.267(100)(012), 2.52(71)(30[bar.3]), 4.361(51) (002), 1.762(39)(32[bar.3]), 4.924 (34)(010), 2.244(32)(31[bar.3]), 1.455(24)(006), 1.996(21)(014), 1.565(20) (611), and 2.353(18)(41[bar.1]). XANES Te [L.sub.III]-edge spectra of a selection of Te minerals (including xocolatlite) and inorganic compounds showed that the position of the absorption edge can be reliably related to the oxidation state of Te. XANES demonstrated that xocolatlite contains [Te.sup.6+] as a tellurate group. Water has been tentatively included in the formula based on IR spectroscopy that indicated the presence of a small amount of water. Raman, IR, XANES, and X-ray diffraction data together with the chemical composition show a similarity of xocolatlite to kuranakhite. A possible series may exist between these two species, xocolatlite being the Ca-rich end-member and kuranakhite the Pb-rich one. Keywords: Xocolatlite, Kuranakhite, new mineral, XANES spectroscopy, tellurium oxidation state, Moctezuma, Sonora, Mexico

The x-ray diffraction studies of ternary and quaternary molybdenum cluster chalcohalides show that these are positively charged zigzag chains containing Te-halide ions.

The structures of two Te-X glasses with compositions T[e.sub.2]C[l.sub.1.9][I.sub.0.1] and T[e.sub.2]C[l.sub.1.5][I.sub.0.5] were studied by reverse Monte Carlo (RMC) fits to the corresponding structure factors obtained from high-energy X-ray diffraction measurements. The results show that these glasses are made up of structural fragments that are present in both tellurium tetrahalides and in low-valent tellurium subhalides.

The chlorination of bis(supermesityl)ditelluride RTeTeR (R = 2,4,6-t-[Bu.sub.3][C.sub.6][H.sub.6]) with 3 equiv of sulfuryl chloride S[O.sub.2][Cl.sub.2] has provided the unstable supermesityltellurium(IV) trichloride RTe[Cl.sub.3] as bright yellow crystals. X-ray crystallography is used to characterize the resulting compounds and depending on the aggregate state and the absence or presence of water, four distinctively different decomposition pathways are identified.

Two anaerobes originally isolated for their abilities to respire selenium oxyanions are shown to achieve growth by reduction of either tellurite [Te(IV)] or tellurate [(Te(VI)] to tellurium [Te(0)]. The use of microorganisms for generating Te nanomaterials is an alternative method for bench-scale process.

The enhancement of intense blue and red upconversion emissions can be found in [Tm.sup.3+] doped tellurite glass when codoped with [Yb.sup.3+] ions on pumping with 798 nm radiations. The frequency upconversion responsible for the enhancement of blue emission signal is attributed to the cooperative energy transfer from pairs of excited [Yb.sup.3+] ions to [Tm.sup.3+] ions.

Systematic vaporization studies were conducted on four three-phase regions to understand the Mn-Te-O system. The results obtained in the study led to a prediction based on a thermochemical assessment that when oxygen potential in the fuel-clad gap of mixed-oxide-fuelled fast breeder nuclear reactors reach certain high values, ternary Mn-Te-O phases could be formed on an stainless steel (SS) clad besides binary metal tellurides.

A novel microwave-assisted growth and characterization of high-quality CdTe/CdS core-shell nanocrystals in the aqueous phase is presented. The results have given a rapid microwave synthesis for producing highly fluorescent CdTe/CdS core-shell nanocrystals, and have also presented some advantages of the microwave synthesis in comparison to the illumination method.

A novel method, the program process of microwave irradiation (PPMI), is described to synthesize high-quality CdTe nanocrystals in aqueous solution. A series of highly luminescent CdTe nanocrystals are rapidly prepared in aqueous phase through PPMI, emphasizing PPMI to be a significant approach to directly prepare high-quality nanocrystals in the aqueous phase, as it is convenient, rapid, and free of complicated vacuum manipulation or expensive chemical reagents.

A rotating electrode is used to examine the electrodeposition of [Bi.sub.2][Te.sub.3] nanowires into alumina templates. The agitation of bath by a rotating electrode not only provides a nearly constant supply of electrolyte to the electrode surface but also increases the wire growing rate and hence as a consequence, the ordered and uniform [Bi.sub.2][Te.sub.3] nanowires array can be obtained efficiently with our rotating electrode.

A new low-temperature, one-pot method is proposed for the synthesis of organically passivated HgTe nanocrystals, without the use of highly toxic precursors. Particle growth is self-limited by temperature quenching, so a narrow size distribution is obtained and the measured size of the particles agrees with calculations using the pseudopotential method.

CdTe nanoparticles stabilized by L-cysteine are chemically transformed into CdS nanoparticles of the same diameter through an intermediate CdTeS alloy without any auxiliary source of sulfur and this reaction is induced by ethylenediaminetetraacetic acid dipotassium salt dehydrate. The slow rate of the CdTe forward alloy forward CdS transition is vital for minimizing defects in the crystal lattice and results in a substantial increase of the quantum yield of photoluminescence over the course of the transition.

The amorphous films of the GeTe(1-x)-Sb2Te3(x) pseudobinary compounds [0(less than or equal to)x(less than or equal to)2/3], which are obtained by substituting Sb2Te2 for GeTe, are crystallized into simple NaCl-type structures, regardless of their compositions, through instantaneous laser irradiation. The results have shown that when the ratio of Sb2Te3 increases, vacancies are intrinsically generated, which makes sure that valence electrons provided by adjacent Ge/Sb and Te atoms remain constant to preserve crystal chemical stability.

The F5TeN(H)Xe(super +) cations is obtained as the product of the reactions of [F5TeNH3][AsF6] with XeF2 (HF and BrF5 solvents) and F5TeNH2 with [XeF][AsF6] (HF solvent) and characterized in solution by multi-NMR spectroscopy. The decomposition route is consistent with the high covalent character of the Xe(II)-N bond and nucleophelic attack at the nitrogen of the nitrenium ion by a fluoride ion donor leads to Xe gas formation and the formation of the fluoramine, F5TeNF2.

Organic (CNT)-inorganic (CdTe) nanohybrids were systematically devised and tested as donor-acceptor nanohybrids in dilute condensed media and as integrative components at electrode surfaces. The novel nanohybrids were characterized both in the ground and excited states with specific accent on electron-transfer chemistry.

Investigation of branching in semiconductor nanocrystals, which leads to tetrapods and to complex architectures, is conducted. High-resolution transmission electron microscopy reveals that branching region in tetrapods is characterized by the presence of multiple wurtzite domains.

The study describes the location and roles of the surface Te, Nb, and Sb oxides in selective propane oxidation over the model bulk Mo-V-O catalyst possessing the orthorhombic (M1) structure. The outermost surfaces and subsurface layers of the orthorombic (M1) Mo-V-O catalysts promoted with Te, Nb, and Sb oxide species at submonolayer surface coverage were examined by low-energy ion scattering (LEIS).

An investigation is conducted on chemiluminescence (CL) of CdTe nanocrystals (NCs) induced by directly chemical oxidation and its size-depended surfactant-sensitized effect in aqueous solution. Results indicated that CdTe NCs could be directly oxidized to produce strong CL emission in basic conditions, especially by hydrogen peroxide and potassium permanganate oxidants.

The synthesis and characterization of two isostructural mixed valent tellurium oxides, A(sub 4)[Te(sub 5)(super 6+)Te(sub 3)(super 4+)]O(sub 23) (A = Rb and K) by X-ray diffraction and infrared spectroscopy is presented. It is revealed that there is a chance for the synthetic and structural solid- state chemistry of new mixed-valent tellurium oxides.

The synthesis and properties of selenites or telluites containing additional MoOsub 4) tetrahedra of MoO(sub 6) are described. It is believed that other lanthanide luminescent compounds can be developed by applying two types of inorganic anions as luminescent activators for lanthanide(III) ions.

The synthesis and characterization of a series of organochalcogen(Se, Te) compounds derived from benzyl alcohol are described. Organo dichalcogenides having hydroxy group ortho to selenium/tellurium with weak intramolecular chalcogen...OH interactions is structurally characterized.

Several novel organoselenium and tellurium compounds are prepared and evaluated as mimetics of the selenoenzyme glutathione peroxidase, which protects cells from oxidative stress by reducing harmful peroxides with the thiol glutathione. The aromatic derivatives proved to be inferior catalysts compared to the cyclic seleninate ester and spirodioxyselenurane.

The inter-nanocrystals (NCs) interactions among pristine assemblies, electrostatically mixed assemblies, and covalently linked NCs assemblies of CdTe NCs stabilized with thioamine and thio acid surfactants were compared. The spectral overlaps between the adsorption and emission curves, the PL red shift, the PL decay curves, and the calculated FRET revealed that covalently linked NCs have the strongest inter-NCs interaction, while CdTe(TGA) NCs act as the most efficient donors.

The importance of specific interactions between heavier nonmetals is increasingly recognized. In addition to halogen-halogen, chalcogen-chalcogen, and pnictogen-pnictogen interactions, the chalcogen-halogen contacts to be added to the list of noncovalent interactions essential for specific packing and supramolecular aggregation.

The products formed using an ambient-temperature hydrazine solvent approach for dissolving ZnTe, just like the main-group-metal sulfides and selenides, are presented. The results show that one-dimensional (1D) polymorphs are soluble in hydrazine and it can be used as convenient precursors for the low-temperature solution processing of p-type ZnTe semiconducting films.

Abstract -- Procedure were proposed for the radiochemical neutron activation analysis of [Mn.sub.x][Hg.sub.1 - x]Te using an AV-17-HCl chromatography system for separating macro and micro components. Using a combination of [...]

We report on the development of nuclear radiation detectors based on epitaxially grown thick single crystalline CdTe layers. The optimization of the CdTe growth on the GaAs substrates in a metalorganic vapor phase epitaxy resulted high-structural quality and thick CdTe layers of thickness up to 200 [micro]m. Radiation detectors were fabricated in p-CdTe/n-CdTe/[n.sup.+]-GaAs structure, where a 2-5 [micro]m thick iodine-doped n-CdTe buffer layer was first grown on the [n.sup.+]-GaAs substrate, followed by about 100-[micro]m-thick undoped p-like CdTe layer. The detectors exhibited good rectification property and good charge transport property. They showed reverse bias leakage currents typically from 1 to 5 [micro]A/[cm.sup.2] at 40-V bias, and clearly demonstrated energy discrimination capability by resolving the 59.5-keV gamma peak from the [sup.241]Am radioisotope during the radiation detection test. Some results on direct growth of CdTe epilayers on Si substrates are also presented. Index Terms--CdTe, energy resolution, heterojunction diode, MOVPE, radiation detector, thick epitaxial layers.

The evolution of defect structure and self-compensation is theoretically studied within quasichemical formalism in undoped and donor-doped Te-saturated CdTe during the cooling in the temperature interval 700[degrees]C-100[degrees]C. We show, that proper thermal treatment, including low temperature (cca 200[degrees]C) dwell, allows to prepare semi-insulating CdTe with deep level doping below the limit [10.sup.13] [cm.sup.-3], which is demanded in detector industry. New high-temperature transport data are used to refine on previous native defect properties for the modeling. Variant defect models are analyzed. Diffusion rates at lowered temperature are annotated to approve the model for real-time experimental verification. Index Terms--CdTe, deep defect, detector, self-compensation.

The interband transitions and the electron activation energy are determined by analyzing the effect of rapid thermal annealing on CdTe/ZnTe quantum dots (QDs). The results reveal that the crystallinity of the CdTe/ZnTe QDs is improved by annealing and they can also help in understanding the thermal annealing effect on the optical properties of CdTe/ZnTe QDs.

The pathway of the formation of five-membered Cl2TeESN2 rings by the reactions of (Me3SiNSN)2 with TeCl4 (E=S, Se) is discussed. The reaction of (Me3SiNSN)2Se with [PPh4]2[Pd2X6] yields [PPh4]2[Pd2(mu-Se2N2S)X4] (X=Cl, Br), the first examples of complexes of the (Se2N2S)(super 2-) ligand and it is found that in both these cases (Se2N2S)(super 2-) ligand bridges the two palladium centers through the selenium atoms.

A convenient synthesis of coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolinones by a tellurium-triggered cyclization is developed. The telluride method is advantageous as it involves nonbasic conditions and avoids nonspecific proton removal that is troublesome in the Kostanecki-Robinson reaction.

Two new mixed-metal tellurites Na1.4Nb3Te4.9O18 and NaNb3Te4O16 is synthesized by standard solid-state techniques using Na2CO3, Nb2O5, and TeO2 as reagents. The structures of Na1.4Nb3Te4.9O18 and NaNb3Te4O16 are determined by single-crystal X-ray diffraction.

Quantitive yields of [((super t)BuNH)Te(mu-N(super t)Bu)2Te(N(super t)Bu)][OSO2CF3] is obtained by the treatment of [((super t)BuNH)Te(mu-N(super t)Bu)2Te(N(super t)Bu)] with HCF3SO3. The study reports about the crystal structures of the partially hydrolyzed products such as [((super t)BuIN)Te(mu-N(super t)Bu)2Te(mu-O)]2(I3)2, [((super t)BuMeN)Te(mu-N(super t)Bu)2Te(mu-O)]2(I3)2, and [((super t)BuMeN)Te(mu-N(super t)Bu)2Te(mu-O)]2(I3)2.2MeCN.

Several distinct oxidation and reduction peaks in the voltammograms were demonstrated by electrochemical studies of thiol-capped CdTe nanocrystals inaqueous solution with the peak positions being dependent on the size of the nanocrystals. An extraordinary behavior is found for the oxidation peak observed at less positive potentials.

Various steps carried out for efficient introduction, manipulation, and removal of organoselenium species are discussed. The toxicological and pharmacological effects of a variety of organoselenium and organotellurium compounds along with their molecular targets are presented.

The effects of potassium tellurite (K2TeO3) on the cell viability of the facultative phototroph Rhodobacter capsulatus are described. The data is taken as evidence that in anaerobic aquatic habitats, the facultative phototroph R. capsulatus may act as a natural scavenger of the highly soluble and toxic oxyanion tellurite.

The energy transfer between polystyrene beads coated with CdTe as donors and Alexaflour molecules as acceptors is analyzed. The study demonstrated that the system is a very promising candidate for fluorescence-resonance energy transfer (FRET)- scanning near-field optical microscopy (SNOM) applications and single molecules.

Semiconductor alpha- MoT (sub 2) nanorods are synthesized by annealing Te-seeded particles of an amorphous MoTe (sub 2) intermediate. This intermediate is prepared by a solution reaction between MO(Co)(sub 6) and an element Te in diphenylmethante.

The use of electrochemical deposition technique for the successful preparation of large area, uniform, continuous and ordered Bi(sub2)Te(sub3) is described. It is suggested that this technique could possibly help synthesize other metal, semimetal or semiconductor single crystal nanowire arrays.

The reactions of Cd[Cl.sub.2] or Hg[Cl.sub.2] with [{[Li.sub.2][Te [(N-t-Bu).sub.3]]}.sub.2] in n-hexane-THF give rise to two distinctly different types of product. In the former case the complexes [Li[(THF). sub.x]][[(CdCl).sub.3][{Te[(N-t-Bu).sub.3]}.sub.2]] (7a (x = 4), 7b (x = 3)) are obtained. The tetrasolvated complex 7a is a solvent-separated ion pair. The trisolvated complex 7b is a contact ion pair in which the fourth coordination site at the [Li.sup.+] centre is occupied by one of the Cl ligands of the anion. The polycyclic anion in 7a and 7b is comprised of two tripodal [[Te[(N-t-Bu).sub.3]].sup.2-] dianions that exhibit different coordination modes to the three Cd[Cl. sup.+] units. One ligand is N,N'-chelated to all three metal centres, and each nitrogen atom bridges two Cd atoms, whereas the other is bonded in a tris-N-monodentate fashion in 7b. In 7a there is an additional weak Cd-N interaction. The reaction of Hg[Cl.sub.2] with [{[Li.sub.2][Te[(N-t-Bu).sub.3]]}.sub.2] produces the adduct [t-BuNTe [([mu]N-t-Bu).sub.2]TeN-t-Bu]Hg[Cl.sub.2] (8), in which the dimeric tellurium diimide ligand in its cis(exo,exo) configuration is N, N'-chelated to mercury. Polymeric strands parallel to the b axis are formed by weak Te***Cl interactions (3.5248(16) [Angstrom], 3.5876(15) [Angstrom]) involving both Cl atoms, but only one Te atom of the ligand. Key words: imido ligands, cadmium, mercury, tellurium.

Colloidally prepared CdTe nanocrystals are studied. A photoemission study was performed to reveal if there are structural differences in the nanocrystals and a structure model is proposed to explain the differences in luminescence efficiency.

A study of the uderpotential depostion (UPD) of Te monolayers onto Au electrodes from perchloric acid solution using electrochemical quartz microgravimetry (EQCM) and chronocoulometry is reported. Analysis of the current time data indicates that this process occurs by a two-dimensional instantaneous nucleation and growth mechanism, resulting in an ordered overlayer with a fractional coverage of ca. 0.41.

High-temperature mass spectrometric studies on xMnO + (1-x)TeO2 samples with x=0.50, 0.54, 0.57, 0.67, 0.75, and 0.79 were conducted to investigate the vaporization behavior of the MnO-TeO2 binary system. The observation led to the inference that the MnO-rich region of the MnO + TeO2 system is not inclined to remain binary during vaporization.

The synthesis, crystal structure and characterization of a non-centrosymmetric oxide, TeSeO(sub 4), are reported. Powder second-harmonic generating (SHG) measurements on TeSeO4 revealed a doubling efficiency of approximately 400 times SiO2.

Structural models of alkali tellurite glasses, (M2O)(sub x)(TeO2)(sub 1-x) with M= Li, Na, K are depicted. The glass structure is investigated by means of the reverse Monte Carlo algorithm, neutron, and X-ray diffraction, NMR spectroscopy.

Spectroscopic and single-crystal X-ray analysis is used to characterize and study the different routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers. The increase in the barriers for interconverting the syn and anti atropisomers during movement from the analogous S to Se to Te compounds is attributed to the rotation about the aryl-aryl bond and much lower barriers for rotation about the aryl-chalcogen bond.