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Yttrium
Terms modified by Yttrium Selected AbstractsSynthesis and Structure of Aminopyridinato-Stabilized Yttrium and Lanthanum Amides and Their Reactivity towards Alkylaluminium CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2009Christian Döring Abstract A series of aminopyridinato-stabilized (amido)lanthanide complexes has been synthesized and characterized. The bulky aminopyridines (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine (1a) and [6-(2,4,6-triisopropylphenyl)pyridin-2-yl](2,4,6-trimethylphenyl)amine (1b) were introduced by amine elimination reaction with [Ln{N(SiHMe2)2}3(thf)2] (Ln = Y, La, thf = tetrahydrofuran, Me = methyl) to obtain the corresponding mono(aminopyridinato) complexes. Single-crystal X-ray analyses were carried out for the yttrium derivatives. The complexes are not able to undergo coordinative chain transfer polymerization with ethylene in the presence of alkylaluminium compounds as the corresponding dialkyl complexes do. Investigations of the reactions of the lanthanide aminopyridinato complexes with triethylaluminium or diisobutylaluminium hydride reveal a fast transfer of the aminopyridinato ligand to the aluminium atom. The products of this transfer reaction are aminopyridinato-stabilized dialkylaluminium compounds. One example of these aluminium complexes was characterized by X-ray crystal structure analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Stability Constants and Dissociation Rates of the EDTMP Complexes of Samarium(III) and Yttrium(III)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008Ferenc Krisztián Kálmán Abstract The stability constants of Sm(EDTMP) (log,KML = 20.71) and Y(EDTMP) (log,KML = 19.19) were determined by a competition reaction between the Ln3+ ion (Ln3+ = Sm3+ or Y3+) and Cu2+ for the EDTMP ligand by spectrophotometry at pH , 10, in the presence of an excess amount of citrate (0.15 M NaCl, 25 °C). For determining the stability constants of Cu(EDTMP) (log,KML = 19.36) and Ca(EDTMP) (log,KML = 8.71) pH,potentiometry was used. In the pH range 4,9 the EDTMP complexes are present in the form of nonprotonated and mono-, di- and triprotonated species. The Ca2+ ion forms a dinuclear complex with Ln(EDTMP). In a simplified blood plasma model consisting of Sm3+, Ca2+ and Zn2+ metal ions, EDTMP, citrate, cysteine and histidine ligands, Sm3+ is practically present in the form of [Sm(HEDTMP)Ca]2,, whereas Zn2+ predominantly forms [Zn(HEDTMP)]5, and [Zn(H2EDTMP)]4, complexes. For studying the dissociation rates of the complexes, the kinetics of the metal exchange (transmetallation) reactions between the Ln(EDTMP) complexes and Cu2+,citrate were investigated in the pH range 7,9 by the stopped-flow method. The rates of the exchange reactions are independent of the Cu2+ concentration and increase with the H+ concentration. The rate constants, characterizing the proton-assisted dissociation of the Ln(EDTMP) complexes, are several orders of magnitude higher than those of the similar Ln(EDTA) complexes, because the protonation constants of Ln(EDTMP) are high and the protonated Ln(HEDTMP) and Ln(H2EDTMP) species are present in higher concentration. The half-times of dissociation of Sm(EDTMP) and Y(EDTMP) at pH = 7.4 and 25 °C are 4.9 and 7.5 s, respectively. These relatively short dissociation half-time values do not predict the deposition of Ln3+ ions in bones in the form of intact Ln(EDTMP) complexes. It is more probable that sorption of the EDTMP ligand and Sm3+ or Y3+ ions occurs independently after the dissociation of complexes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Yttrium ,-Diketonate Glyme MOCVD Precursors: Effects of the Polyether Length on Stabilities, Mass Transport Properties and Coordination SpheresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2004Graziella Malandrino Abstract The glyme adducts of trishexafluoroacetylacetonato yttrium, [Y(hfa)3·monoglyme], [Y(hfa)3·diglyme], [Y(hfa)3·(H2O)2·triglyme] and [Y(hfa)2·tetraglyme]+[Y(hfa)4], {CH3(OCH2CH2)nOCH3, n = 1 monoglyme, 2 diglyme, 3 triglyme and 4 tetraglyme}, were synthesized and characterized by elemental analysis, mass spectrometry, and IR, 1H and 13C NMR spectroscopy. Additionally, [Y(hfa)3·monoglyme] and [Y(hfa)3·diglyme] were characterized by single-crystal X-ray diffraction studies. The mass-transport properties of these adducts were investigated by thermogravimetric analysis, differential scanning calorimetry, evaporation-rate measurements and chemical vapour-deposition experiments. There is evidence of high volatility and very good thermal stabilities with a residue lower than 2,4 %. Vaporization-rate experiments proved that all adducts are well-suited for metal-organic chemical vapour-deposition experiments. The [Y(hfa)3·monoglyme] complex was successfully applied in the low-pressure MOCVD process of YBaCuO HTc superconductor using a multimetal molten single source. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Nonoperative therapies for combined modality treatment of hepatocellular cancer: expert consensus statementHPB, Issue 5 2010Roderich E. Schwarz Abstract Although surgical resection and liver transplantation are the only treatment modalities that enable prolonged survival in patients with hepatocellular carcinoma (HCC), the majority of HCC patients presents with advanced disease and do not undergo resective or ablative therapy. Transarterial chemoembolization (TACE) is indicated in intermediate/advanced stage unresectable HCC even in the setting of portal vein involvement (excluding main portal vein). Sorafenib has been shown to improve survival of patients with advanced HCC in two controlled randomized trials. Yttrium 90 is a safe microembolization treatment that can be used as an alternative to TACE in patients with advanced liver only disease or in case of portal vein thrombosis. External beam radiation can be helpful to provide local control in selected unresectable HCC. These different treatment modalities may be combined in the treatment strategy of HCC and also used as a bridge to resection or liver transplantation. Patients should undergo formal multidisciplinary evaluation prior to initiating any such treatment in order to individualize the best available options. [source] Yttrium(III)-Catalyzed Intramolecular Alkyne HydroaminationsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2006Hyunseok Kim Abstract The neutral Y(III) complex 4 has been shown to be an effective precatalyst for intramolecular alkyne hydroaminations that provide cyclic amines in good to excellent yields. [source] Deposition of 90YPO4 and 144CePO4 radioisotopes on polymer surfaces for radiation delivery devicesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2002Xin Qu Abstract Intravascular irradiation with , emitters inhibits restenosis in arteries after balloon angioplasty or stent implantation. Yttrium-90 (90Y, T1/2=64 h) and cerium-144 (144Ce, T1/2=286 d) emit beta particles (Emax=2.28,3.50 MeV) having an ideal energy range for brachytherapy delivery system. In this article, a previously reported method for depositing 32P on poly(ethylene terephtalate) (PET) surfaces is generalized and modifications that allow deposition of other ,-emitting radioisotopes, such as 90Y and 144Ce, are demonstrated. PET films were first coated with chitosan hydrogel and then adsorbed different amounts of phosphoric acid (PA) in aqueous solutions. Yttrium was deposited onto the surface as YPO4 after the films were immersed in YCl3 solutions. 1 ,Ci 90YCl3 (2×10,9 g) was used in each sample as a tracer for measuring the deposition efficiency, which is defined as the percentage of YCl3 deposited on the surface compared to the amount of YCl3 in solutions before the deposition. In order to improve the safety of brachytherapy treatments, polyurethanes were used to seal the deposited radioisotopes on the surface to minimize the leakage of the isotopes into the patients. The generality of this method presented here for a wide variety of particular radioisotopic components allows design of a broad range of versatile radioisotope sources. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 98,105, 2002; DOI 10.1002/jbm.10095 [source] Yttrium(III) complex as a highly active catalyst for lactide polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2006Linda M. Hodgson The synthesis, characterization, and X-ray crystal structure of a well-defined yttrium(III) amide complex with the bis(thiophosphinic amide) ligand is reported. The new complex exhibits high rates and good control for lactide polymerization. The polymerization kinetics and mechanism are studied under a range of different conditions, and these show that even under mild conditions this complex exhibits polymerization rates among the fastest known. [source] Synthesis of Yttrium,Aluminum,Garnet Hollow Microspheres by Reverse-Emulsion TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006Minati Chatterjee Yttrium,aluminum,garnet (YAG, Y3Al5O12) hollow microspheres were synthesized by reverse-emulsion (w/o) technique starting with aqua-based precursors of oxides. The non-ionic surfactant was used as the emulsifying agent. The gel powders were calcined at 700°,1200°C. The synthesized powders were characterized by differential thermal analysis (DTA), thermogravimetry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The appearance of an exothermic peak at 932°C in the DTA curve revealed the crystallization of YAG, which was further confirmed by XRD and FTIR studies. SEM confirmed the formation of hollow microspheres. [source] Effect of Yttrium and Erbium Ions on Epitaxial Phase Transformations in AluminaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2003Deirdre D. Ragan The effect of low concentrations of Y, Er, and Cr solutes on the amorphous-to-, transformation and on the ,-to-, transformation in aluminum oxide has been studied in situ by time-resolved reflectivity. The activation energies of the two transformations with these dopants are the same as in undoped alumina, being 4.1 ± 0.1 and 5.2 ± eV, respectively. Although not affecting the activation energies, Y, Er, and Cr do affect the transformation kinetics. Y and Cr ions decrease the ,-to-, transformation velocity and, over the limited range studied, do so in proportion to their concentration. Concentrations of Er as low as ,6 ppm retard the ,-to-, transformation and concentrations of 32 ppm essentially stop the transformation occurring within the times and temperatures accessible within the present experiment, thereby preventing quantification of the effect of Er on the ,-phase transformation. Erbium also retards the amorphous-to-, transformation relative to undoped alumina whereas yttrium and chromium accelerate it. [source] Distribution of Cerium Ions in Cerium-Doped ,,-SiAlON and Its Effect on Grain MorphologyJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2002Fang-Fang Xu Cerium-doped ,,-SiAlON material was prepared by spark plasma sintering at 1750°C under 30 MPa pressure for 10 min. Yttrium ,,-SiAlON seeds (1 wt%) were added to the starting powder mixture. Recent work showed that up to 45 wt% of ,,-SiAlON phases are formed in the present sintered ceramics. The material presented a microstructure, containing rodlike cerium-doped ,,-SiAlON crystals. In this paper, transmission electron microscopy and energy dispersive spectroscopy examinations of the ,,-SiAlON grains are reported. The structural analyses revealed a high density of domain boundaries, within which larger amounts of cerium ions were segregated than in the matrix. The density of the domain boundaries was proportional to the amount of incorporated cerium ions. These structural defects eventually dominated the growth habits of the ,,-SiAlON crystals, by modifying the structure of the interstices at the boundary sites. The role of yttrium ,,-SiAlON seeds also is discussed in this paper. [source] ChemInform Abstract: Bis- and Mono(amidate) Complexes of Yttrium: Synthesis, Characterization, and Use as Precatalysts for the Hydroamination of Aminoalkenes.CHEMINFORM, Issue 51 2009Louisa J. E. Stanlake Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Exceptionally Active Yttrium,Salen Complexes for the Catalyzed Ring Opening of Epoxides by TMSCN and TMSN3.CHEMINFORM, Issue 10 2008Biswajit Saha Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Ligand-Assisted Rate Acceleration in Transacylation by an Yttrium,Salen Complex.CHEMINFORM, Issue 37 2002Demonstration of a Conceptually New Strategy for Metal-Catalyzed Kinetic Resolution of Alcohols. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Investigation of Yttrium and Polyvalent Ion Intercalation into Nanocrystalline Vanadium Oxide.CHEMINFORM, Issue 45 2001G. G. Amatucci Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Bis(amido)cyclodiphosph(III)azane Complexes of Yttrium and the LanthanidesCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2009Marcus Rastätter Dr. Abstract The first cyclodiphosph(III)azane complexes of the rare-earth elements have been synthesized. Reactions of the lithium salt cis -[(tBuNP)2(tBuN)2{Li(thf)}2] with anhydrous yttrium trichloride or the heavier lanthanide trichlorides resulted in the corresponding cyclodiphosph(III)azane complexes [Li(thf)4][{(tBuNP)2(tBuN)2}LnCl2] (Ln=Y (1,a), Ho (1,b), Er (1,c)). The single-crystal X-ray structures showed that compounds 1,a,c consisted of ion pairs composed of a [Li(thf)4]+ cation and a C2v symmetric [{(tBuNP)2(tBuN)2}LnCl2], anion. By treating cis -[(tBuNP)2(tBuN)2{Li(thf)}2] with anhydrous SmCl3 in THF, the trimetallic complex [{(tBuNP)2(tBuN)2}SmCl3Li2(thf)4] (2) was obtained. The influence of the ionic radii of the lanthanides can be seen in the single-crystal X-ray structure of compound 2, which forms a six-membered Cl-Li-Cl-Li-Cl-Sm metallacycle. The ring adopts a boat conformation in which one chlorine atom and the samarium atom are displaced from the Cl2Li2 least-square plane. Heating of the metalate complexes in toluene resulted in the extrusion of lithium chloride and the formation of the neutral dimeric metal chloride complexes of the composition [(tBuNP)2(tBuN)2LnCl(thf)]2 (Ln=Y (3,a), La (3,b) Nd (3,c), Sm (3,d)). Furthermore, treating 1,a with KNPh2 resulted in a lithium metalate complex of the composition [Li(thf)4][{(tBuNP)2(tBuN)2}Y(NPh2)2] (4). The coordination mode of the {(tBuNP)2(tBuN)2}2, ligand in 4 is different to that observed in 1,a,c, 2, and 3,a,d; instead of a symmetric ,2 coordination of the ligand, a heterocubane-type structure is observed in the solid state. The complex [(tBuNP)2(tBuN)2NdCl(thf)] (3,c) was used as a Ziegler,Natta catalyst for the polymerization of 1,3-butadiene to poly- cis -1,4-butadiene. The observed activities of the Ziegler,Natta catalyst strongly depended upon the nature of the cocatalyst; in some case very high turnover rates and a cis selectivity of 93,94,% were observed. [source] Patient Satisfaction and Reported Long-Term Therapeutic Efficacy Associated with 1,320 nm Nd:YAG Laser Treatment of Acne Scarring and PhotoagingDERMATOLOGIC SURGERY, Issue 3 2006ASHISH C. BHATIA BACKGROUND AND OBJECTIVE Nonablative laser treatments have become increasingly used for the treatment of acne scarring and photoaging. While nonablative laser treatments are more convenient and relatively safer than ablative laser resurfacing, efficacy and patient satisfaction with the level of improvement of textural abnormalities in acne scarring and rhytids associated with photoaging needs further study. DESIGN/MATERIALS AND METHODS Structured interviews were performed with 34 patients from a referral-based academic practice who each previously received a series of 6 monthly treatments with a 1,320 nm neodymium:yttrium,aluminum,garnet (Nd:YAG) laser for treatment of acne scarring or photoaging. Topical anesthesia was applied 1 hour before each treatment. Patients were interviewed at least 3 months after cessation of treatment (range 3,12 months). RESULTS Patients tolerated the treatments well. Combined results for acne scarring and photoaging patients were as follows: (a) patient satisfaction with treatment was rated at 62%, and (b) textural improvement was reported at 31% at the end of the six treatments, and 30% at the date of interview. When results were stratified by diagnosis, patient satisfaction was slightly higher for treatment of acne scarring than for photoaging. Overall degree of improvement on a 1,10 scale was 5.4 for acne scarring and 3.8 for wrinkling. CONCLUSION Nonablative treatment with the 1,320 nm Nd:YAG laser induced significant patient-reported improvement in both acne scarring and photoaging. The majority of patients reported satisfaction with the degree of improvement. [source] Pentadentate Ligands for the 1:1 Coordination of Lanthanide(III) Salts,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2007Markus Albrecht Abstract Three hydrazone type ligands, namely 2 -H, 3, and 4, which were designed to form 1:1 complexes with lanthanoid(III) ions, are presented. Although the tetradentate ligand 2, leads to an interesting complex [(2)(2 -H)YCl2] with yttrium(III), a more general principle for the coordination of the metal ions by hydrazone-type ligands can be found with ligand 3, where 1:1 complexes are obtained with an effective coordination of the metal salts by the ligand. The stabledimer [{(3)Nd(CF3SO3)}2(,-CF3SO3)3]CF3SO3 was characterized by X-ray structure determination. Depending on the size of the metal ion, additional co-ligands can also be bound to the metal centers. This is observed in the molecular structures of [(3)Pr(NO3)2(MeOH)2](NO3), [(3)NdCl2(MeOH)(EtOH)]Cl, [(3)ErCl2(MeOH)]Cl, and [(3)LuCl2]Cl. The solid-state molecular structures of 4 and 4·HCl show the helicating ability of this ligand upon metal coordination. The corresponding lanthanide complexes of 4 are characterized by standard techniques such as NMR and CD spectroscopy and mass spectrometry.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Yttrium ,-Diketonate Glyme MOCVD Precursors: Effects of the Polyether Length on Stabilities, Mass Transport Properties and Coordination SpheresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2004Graziella Malandrino Abstract The glyme adducts of trishexafluoroacetylacetonato yttrium, [Y(hfa)3·monoglyme], [Y(hfa)3·diglyme], [Y(hfa)3·(H2O)2·triglyme] and [Y(hfa)2·tetraglyme]+[Y(hfa)4], {CH3(OCH2CH2)nOCH3, n = 1 monoglyme, 2 diglyme, 3 triglyme and 4 tetraglyme}, were synthesized and characterized by elemental analysis, mass spectrometry, and IR, 1H and 13C NMR spectroscopy. Additionally, [Y(hfa)3·monoglyme] and [Y(hfa)3·diglyme] were characterized by single-crystal X-ray diffraction studies. The mass-transport properties of these adducts were investigated by thermogravimetric analysis, differential scanning calorimetry, evaporation-rate measurements and chemical vapour-deposition experiments. There is evidence of high volatility and very good thermal stabilities with a residue lower than 2,4 %. Vaporization-rate experiments proved that all adducts are well-suited for metal-organic chemical vapour-deposition experiments. The [Y(hfa)3·monoglyme] complex was successfully applied in the low-pressure MOCVD process of YBaCuO HTc superconductor using a multimetal molten single source. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Short-Range Structure of Yttrium Alumino-Silicate Glass for Cancer Radiotherapy: Car,Parrinello Molecular Dynamics Simulations,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Jamieson K. Christie We present Car,Parrinello molecular dynamics (CPMD) simulations of yttrium alumino-silicate (YAS) glass. Alumino-silicate glass microspheres are used as vectors of yttrium radioisotopes in cancer radiotherapy; understanding in detail how yttrium is bound within the glass network is important to control the unwanted release of radioactive yttrium in the bloodstream. Our simulations, focused on a specific composition relevant to practical applications, show that silicon and aluminum form a disordered glass network, where Si is mainly four-coordinated, whereas, Al is mainly four- and five-coordinated. Yttrium cations have a network-modifying role, disrupting the alumino-silicate network by breaking Si(Al)O bonds and coordinating the resulting non-bridging oxygens (NBO). The local environment of yttrium in the glass turns out to be rather flexible: between five and eight oxygen atoms, with a marked predominance of NBO, are found coordinated to a central Y cation, leading to a corresponding broad and multimodal distribution of OYO angles. [source] Rare Earth Element Concentrations in the Natural Water Reference Materials (NRCC) NASS-5, CASS-4 and SLEW-3GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2007Michael G. Lawrence terres rares; yttrium; pré-concentration; ICP-MS; matériaux de référence du NRCC The rare earth element and yttrium concentrations of the NRCC reference materials North Atlantic Surface seawater, NASS-5; Coastal Atlantic Surface Seawater, CASS-4; and the estuarine water, SLEW-3 have been precisely determined by ICP-MS after ca. 1:8 preconcentration following a triple chelation using HDEHP (phosphoric acid 2-ethylhexyl ester -mono and di ester mixture) in heptane, and back extraction in nitric acid. We propose reference values with uncertainties for all naturally occurring lanthanides and yttrium. Les concentrations en terres rares et en yttrium des matériaux de référence suivants (du NRCC): l'eau de surface de l'Atlantique Nord NASS-5, l'eau de surface de l'Atlantique Côtier CASS-4 et l'eau d'estuaire SLEW-3 ont été déterminées précisément par ICP-MS aprčs concentration d'un facteur 1 : 8 environ, suivie d'une triple chélation avec de l'HDEHP (mixture d'acide phosphorique 2-ethylhexyl ester - mono et di ester) dans de l'heptane et une extraction inverse en acide nitrique. Nous proposons des valeurs de référence avec leur incertitude pour toutes les terres rares naturelles et l'yttrium. [source] Anionic Bridged Bis(amidinate) Lithium Lanthanide Complexes: Efficient Bimetallic Catalysts for Mild Amidation of Aldehydes with AminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Junfeng Wang Abstract Anionic bridged bis(amidinate) lithium lanthanide complexes have been found to be efficient catalysts for the amidation of aldehydes with amines under mild conditions. The activity follows the order: yttrium Yttria,polystyrene,polypropylene composite for fine dyeable fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Chengbing Yu Abstract Fine polypropylene fiber has many excellent properties, but it is difficult to dye because of the absence of dye sites in the molecular chain and high crystallinity. Fine polypropylene/hybrid polystyrene (yttria) fiber melt-spun from blends of polypropylene and a small amount of nanohybrid polystyrene with modified yttria incorporated was prepared to improve the dyeing properties. The dyeability, orientation, degree of crystallinity, phase morphology, and mechanical properties of pure polypropylene and the blend fibers were investigated. It was found that the crystallinity and morphology of these phases in the blend systems were different. With the existence of nanohybrid polystyrene, the fine modified polypropylene filaments had practical mechanical properties, the amorphous region of the polypropylene/hybrid polystyrene (yttria) fiber increased, and the modified polypropylene fiber dyed easily and had good fastness to soaping because of the complexation of the disperse dye and yttrium in the blend system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Solvent extraction studies of Sm(III) from nitrate medium and separation factors of rare earth elements with mixtures of sec -octylphenoxyacetic acid and 1,10-phenthrolineJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010Shujuan Fan Abstract BACKGROUND: Liquid,liquid extraction is widely used for the separation of rare earths, among which synergistic extraction has attracted more and more attention. Numerous types of synergistic extraction systems have been applied to rare earths with high extraction efficiency and selectivities. In the present study, mixtures of sec -octylphenoxyacetic acid (CA12, H2A2) and 1,10-phenanthroline (phen, B) have been used for the extraction of rare earths from nitrate medium. The stoichiometry of samarium(III) extraction has been studied using the methods of slope analysis and constant molar ratio. The possibility of using synergistic extraction effects to separate rare earths has also been studied. RESULTS: Mixtures of CA12 and phen display synergistic effects in the extraction of rare earth elements giving maximum enhancement coefficients of 5.5 (La); 13.7 (Nd); 15.9 (Sm); 24.5 (Tb); 45.4 (Yb) and 12.3 (Y). Samarium(III) is extracted as SmHA4B3 with mixtures of CA12 and phen instead of SmHA4 when extracted with CA12 alone. The calculated logarithm of the equilibrium constant is 6.0 and the thermodynamic functions, ,H, ,G, and ,S, have been calculated as 4.3 kJ mol,1, , 33.7 kJ mol,1 and 129.7 J mol,1 K,1, respectively. CONCLUSION: Mixtures of CA12 and phen exhibit synergistic effects on rare earth elements. Graphical and numerical methods have been successfully used to determine their stoichiometries. The different synergistic effects may provide the possibility of separating yttrium from heavy lanthanoids at an appropriate ratio of CA12 and phen. Copyright © 2010 Society of Chemical Industry [source] Dating metamorphic reactions and fluid flow: application to exhumation of high- P granulites in a crustal-scale shear zone, western Canadian ShieldJOURNAL OF METAMORPHIC GEOLOGY, Issue 3 2006K. H. MAHAN Abstract The Legs Lake shear zone is a crustal-scale thrust fault system in the western Canadian Shield that juxtaposes high-pressure (1.0+ GPa) granulite facies rocks against shallow crustal (< 0.5 GPa) amphibolite facies rocks. Hangingwall decompression is characterized by breakdown of the peak assemblage Grt + Sil + Kfs + Pl + Qtz into the assemblage Grt + Crd + Bt ± Sil + Pl + Qtz. Similar felsic granulite occurs throughout the region, but retrograde cordierite is restricted to the immediate hangingwall of the shear zone. Textural observations, petrological analysis using P,T/P,MH2O phase diagram sections, and in situ electron microprobe monazite geochronology suggest that decompression from peak conditions of 1.1 GPa, c. 800 °C involved several distinct stages under first dry and then hydrated conditions. Retrograde re-equilibration occurred at 0.5,0.4 GPa, 550,650 °C. Morphology, X-ray maps, and microprobe dates indicate several distinct monazite generations. Populations 1 and 2 are relatively high yttrium (Y) monazite that grew at 2.55,2.50 Ga and correspond to an early granulite facies event. Population 3 represents episodic growth of low Y monazite between 2.50 and 2.15 Ga whose general significance is still unclear. Population 4 reflects low Y monazite growth at 1.9 Ga, which corresponds to the youngest period of high-pressure metamorphism. Finally, population 5 is restricted to the hydrous retrograded granulite and represents high Y monazite growth at 1.85 Ga that is linked directly to the synkinematic garnet-consuming hydration reaction (KFMASH): Grt + Kfs + H2O = Bt + Sil + Qtz. Two samples yield weighted mean microprobe dates for this population of 1853 ± 15 and 1851 ± 9 Ma, respectively. Subsequent xenotime growth correlates with the reaction: Grt + Sil + Qtz + H2O = Crd. We suggest that the shear zone acted as a channel for fluid produced by dehydration of metasediments in the underthrust domain. [source] Yttrium(III) complex as a highly active catalyst for lactide polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2006Linda M. Hodgson The synthesis, characterization, and X-ray crystal structure of a well-defined yttrium(III) amide complex with the bis(thiophosphinic amide) ligand is reported. The new complex exhibits high rates and good control for lactide polymerization. The polymerization kinetics and mechanism are studied under a range of different conditions, and these show that even under mild conditions this complex exhibits polymerization rates among the fastest known. [source] Raman spectroscopic study of the phosphate mineral churchite-(Y) YPO4·2H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2010Ray L. Frost Abstract Raman spectroscopy has been used to study the rare-earth mineral churchite-(Y) of formula (Y,REE)(PO4) ·2H2O, where rare-earth element (REE) is a rare-earth element. The mineral contains yttrium and, depending on the locality, a range of rare-earth metals. The Raman spectra of two churchite-(Y) mineral samples from Jáchymov and Medv,dín in the Czech Republic were compared with the Raman spectra of churchite-(Y) downloaded from the RRUFF data base. The Raman spectra of churchite-(Y) are characterized by an intense sharp band at 975 cm,1 assigned to the ,1 (PO43,) symmetric stretching mode. A lower intensity band observed at around 1065 cm,1 is attributed to the ,3 (PO43,) antisymmetric stretching mode. The (PO43,) bending modes are observed at 497 cm,1 (,2) and 563 cm,1 (,4). Some small differences in the band positions between the four churchite-(Y) samples from four different localities were found. These differences may be ascribed to the different compositions of the churchite-(Y) minerals. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ion imprinted polymer particles for separation of yttrium from selected lanthanidesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2006Ramakrishnan Kala Abstract Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2,-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of , 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid,liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 ± 0.2 to 65.2 ± 0.2% in a single stage of operation. [source] Electric and Dielectric Behaviors of Y-Doped Calcium Copper TitanateJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Fengchao Luo Yttrium-doped CaCu3Ti4,xYxO12,x/2 (x=0,0.1) samples were fabricated by using solid-state sintering, and their electric and dielectric properties were investigated. Yttrium addition has shown to reduce the dielectric loss remarkably while maintaining colossal permittivity. At x=0.5, the loss (tan ,) is below 0.1 over the frequency range from 1 to 300 KHz, while that of the pure ceramic is above 0.1 over most measuring frequency range. The current density,electric field curves proved that yttrium doping can effectively enhance the varistor voltage, indicating a rise of the potential barrier height at the grain boudaries. Local measurement of impedance at the grain boundaries was performed by using microcontact probes. The results indicated that yttrium dramatically increases the resistance of the grain boundaries. The differences are attributed to the enhanced Cu segregation at grain boundaries, which is induced by yttrium doping. [source] Boson Peak, Elastic Properties, and Rigidification Induced by the Substitution of Nitrogen for Oxygen in Oxynitride GlassesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Nicolas F. Richet The effects of the substitution of nitrogen for oxygen on the heat capacity and vibrational entropy of three yttrium aluminosilicate glasses with 0, 3.4, and 7.4 mol% Si3N4 have been investigated from 10 to 300 K. The partial molar heat capacity and entropy of Si3N4 calculated from these and previous measurements indicate stronger average bonding than for SiO2 units, whereas the values derived for Y2O3 are consistent with the dual network modifying and Al3+ charge-compensating role of yttrium. The low-frequency part of the vibrational densities of states g(,) and the boson peaks g(,)/,2 derived from the inversion of the heat capacities indicate that nitrogen rigidifies the TO4 (T=Si, Al) tetrahedral network and that yttrium hampers the librational motion of the AlO4 tetrahedra, which contribute to the excitations associated with the boson peak. Along with data reported previously for borate and silicate glasses, these results for oxynitrides show a general monotonically increasing relation between transverse acoustic velocities and the temperature of the calorimetric boson peak. Illustrating the universal phenomenology of the boson peak, all these data collapse on the same master curve when plotted in a reduced form. [source] Thermochemistry and Crystallization of Glass-Forming Y-Substituted Sr-Analogues of Fresnoite (Sr2TiSi2O8)JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010Tae-Jin Park Strontium titanosilicate (Sr2TiSi2O8) is the Sr-analogue of fresnoite (Ba2TiSi2O8). It may provide useful properties due to the unusual five-coordinate titanium in its structure. Sr2TiSi2O8 is also a possible oxide form for the immobilization of short-lived fission products in radioactive waste. Through , decay, strontium decays to yttrium and then to zirconium. Therefore, not only the stability of Sr-loaded waste forms but also that of a potential decay product series with charge-balance in a naturally occurring mineral or ceramic is of fundamental importance. To incorporate the reaction 3Sr2+=2Y3++vacancy in the fresnoite composition, Y-substituted Sr-analogues of fresnoite, (Sr2,xY2/3x)TiSi2O8 (x=0, 0.5, 0.75, 1, 1.25, and 1.5) were prepared by a high-temperature synthesis and were found to form glass upon cooling. The Y-end-member (Y1.33TiSi2O8, x=2) crystallized to a mixture of Y2TiSiO7, TiO2, and SiO2 upon quenching in air. The enthalpies of formation of Y-substituted Sr-fresnoite glasses were obtained from drop solution calorimetry in a molten lead borate (2PbO·B2O3) solvent at 702°C. The enthalpies of formation from constituent oxides were exothermic but become less so with increasing Y content. The enthalpy of vitrification of Sr2TiSi2O8 composition was measured to be 68.5 ± 6.2 kJ/mol. The thermodynamic stability of the Y-substituted Sr-analogue of crystalline fresnoite may become marginal with increasing yttrium content. Their ready glass formation, even in the absence of radiation, suggests that amorphous phases may dominate as the Sr- and Cs-containing waste forms decay. [source]
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