The present work demonstrates the utility of polymer embedded nanocrystalline titania (TiP) as a new, accessible and viable solid sorbent for the chromatographic separation of high specific activity 77As from neutron irradiated natural GeO2. Experimental parameters such as distribution ratios (Kd), equilibrium sorption capacity, breakthrough capacity and separation yields were determined. A two-step ion-exchange procedure was developed to avail 77As, from irradiated Ge in alkaline medium. The first step involved removal of the bulk Ge from 77As by selective sorption of Ge ions on a TiP column at pH 13. Subsequently, the effluent solution containing 77As was further purified and concentrated by sorption on a small TiP column at pH 10. 77As could be eluted from the second column in 2?C3?mL of 0.1?M NaOH solution with >80% radiochemical yield. The 77As obtained by this method was found to have insignificantly small level of radiocontaminants. 相似文献
The standard molar Gibbs energies of formation of LnFeO3(s) and Ln3Fe5O12(s) where Ln=Eu and Gd have been determined using solid-state electrochemical technique employing different solid electrolytes. The reversible e.m.f.s of the following solid-state electrochemical cells have been measured in the temperature range from 1050 to 1255 K.Cell (I): (−)Pt / {LnFeO3(s)+Ln2O3(s)+Fe(s)} // YDT/CSZ // {Fe(s)+Fe0.95O(s)} / Pt(+);Cell (II): (−)Pt/{Fe(s)+Fe0.95O(s)}//CSZ//{LnFeO3(s)+Ln3Fe5O12(s)+Fe3O4(s)}/Pt(+);Cell (III): (−)Pt/{LnFeO3(s)+Ln3Fe5O12(s)+Fe3O4(s)}//YSZ//{Ni(s)+NiO(s)}/Pt(+);andCell(IV):(−)Pt/{Fe(s)+Fe0.95O(s)}//YDT/CSZ//{LnFeO3(s)+Ln3Fe5O12(s)+Fe3O4(s)}/Pt(+).The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the e.m.f. data. The standard Gibbs energies of formation of solid EuFeO3, Eu3Fe5O12, GdFeO3 and Gd3Fe5O12 calculated by the least-squares regression analysis of the data obtained in the present study are given byΔfG°m(EuFeO3, s) /kJ mol−1 (± 3.2)=−1265.5+0.2687(T/K) (1050 ? T/K ? 1570),ΔfG°m(Eu3Fe5O12, s)/kJ mol−1 (± 3.5)=−4626.2+1.0474(T/K) (1050 ? T/K ? 1255),ΔfG°m(GdFeO3, s) /kJ mol−1 (± 3.2)=−1342.5+0.2539(T/K) (1050 ? T/K ? 1570),andΔfG°m(Gd3Fe5O12, s)/kJ·mol−1 (± 3.5)=−4856.0+1.0021(T/K) (1050 ? T/K ? 1255).The uncertainty estimates for ΔfG°m include the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagrams for the systems Eu-Fe-O and Gd-Fe-O and chemical potential diagrams for the system Gd-Fe-O were computed at 1250 K. 相似文献
A linear synthesis of the major oxepane fragment of zoapatanol, showing the induction of uterine contractions, and cervical dilation and uterine bleeding (by the concentrated zoapatle tea) in early human pregnancy, isolated from the leaves of Mexican zoapatle plant Montanoa tomentosa, is described from known intermediate involving Sharpless asymmetric epoxidation, bis‐epoxide opening reaction with Corey? Chaykovsky reagent, ring‐closing metathesis reaction, and Horner? Wadsworth? Emmons olefination reaction as key steps. 相似文献
Synergism has been observed in the extraction of zirconium(IV) by mixtures of Aliquat 336 or Alamine 336 with a neutral donor TBP from aq. HCl solutions. Although the extractant dependency for Zr(IV) is found to be nearly second power with respect to TBP alone, monosolvate is found to be formed for extraction by its mixture with Aliquat 336 or Almine 336. Quantitative extraction is observed with mixtures at a lower acidity than that with individual extractants. The species formed is tentatively assigned to be Q2ZrCl6. TBP, where
for Aliquat 336 and
for Alamine 336. 相似文献
A visible light driven, direct Z‐scheme reduced graphene oxide–Ag3PO4 (RGO–Ag3PO4) heterostructure was synthesized by means of a simple one‐pot photoreduction route by varying the amount of RGO under visible light illumination. The reduction of graphene oxide (GO) and growth of Ag3PO4 took place simultaneously. The effect of the amount of RGO on the textural properties and photocatalytic activity of the heterostructure was investigated under visible light illumination. Furthermore, total organic carbon (TOC) analysis confirmed 97.1 % mineralization of organic dyes over RGO–Ag3PO4 in just five minutes under visible‐light illumination. The use of different quenchers in the photomineralization suggested the presence of hydroxyl radicals ( . OH), superoxide radicals ( . O2?), and holes (h+), which play a significant role in the mineralization of organic dyes. In addition to that, clean hydrogen fuel generation was also observed with excellent reusability. The 4 RGO–Ag3PO4 heterostructure has a high H2 evolution rate of 3690 μmol h?1 g?1, which is 6.15 times higher than that of RGO. 相似文献
E.m.f. measurements on cells of the type Ag(s), AgCNS(s), KCNS(c)//KCl(c), AgCl(s), Ag(s) in four different composition of urea—water mixtures at seven different temperatures from 5 to 35°C have been made to determine the standard potentials of the silver—silver thiocyanate electrode in these media. These values have been used to evaluate the transfer thermodynamic quantities accompanying the transfer of 1 g ion of CNS? ion from the standard state in water to the standard state in urea—water mixtures. 相似文献
Currently, 188Re is obtained from 188W/188Re chromatographic generator containing alumina which has a limited capacity (~80 mg Wg?1) for 188W. This results in high bolus volumes of 188Re, which often needs to be concentrated before radiolabeling. We have demonstrated the feasibility of using polymer embedded nano crystalline titania (TiP), a novel high capacity sorbent material (~300 mg Wg?1), for developing a 188W/188Re chromatographic generator. A TiP based chromatographic 188W/188Re generator was developed in which 188Re could be eluted with 0.9% saline solution. About 90% of the 188Re could be recovered in the first 4–5 mL of total activity with more than 80% yield. The purity of 188Re is adequate for clinical applications. 相似文献
Magnolia champaca (L.) Baill. ex Pierre of family Magnoliaceae, is a perennial tree with aromatic, ethnobotanical, and medicinal uses. The M. champaca leaf is reported to have a myriad of therapeutic activities, however, there are limited reports available on the chemical composition of the leaf essential oil of M. champaca. The present study explored the variation in the yield and chemical composition of leaf essential oil isolated from 52 accessions of M. champaca. Through hydrodistillation, essential oil yield was obtained, varied in the range of 0.06 ± 0.003% and 0.31 ± 0.015% (v/w) on a fresh weight basis. GC-MS analysis identified a total of 65 phytoconstituents accounting for 90.23 to 98.90% of the total oil. Sesquiterpene hydrocarbons (52.83 to 65.63%) constituted the major fraction followed by sesquiterpene alcohols (14.71 to 22.45%). The essential oils were found to be rich in β-elemene (6.64 to 38.80%), γ-muurolene (4.63 to 22.50%), and β-caryophyllene (1.10 to 20.74%). Chemometrics analyses such as PCA, PLS-DA, sPLS-DA, and cluster analyses such as hierarchical clustering, i.e., dendrogram and partitional clustering, i.e., K-means classified the essential oils of M. champaca populations into three different chemotypes: chemotype I (β-elemene), chemotype II (γ-muurolene) and chemotype III (β-caryophyllene). The chemical polymorphism analyzed in the studied populations would facilitate the selection of chemotypes with specific compounds. The chemotypes identified in the M. champaca populations could be developed as promising bio-resources for conservation and pharmaceutical application and further improvement of the taxa. 相似文献
Zinc sulfide (ZnS) nanoparticles have been successfully prepared by sol–gel precipitation method. The successful formation of cubic structure is ensured by XRD analysis and Debye Scherrer’s equation is used to determine the crystallite size which was found to be 36 nm for ZnS sample annealed at 200 °C. Surface morphology was studied using HRSEM as well as HRTEM and lattice parameters of the samples were obtained from SAED pattern which was found to have close resemblance to values attained from XRD pattern. Further elemental mapping of ZnS nanoparticles is confirmed by EDX studies. Further Kubelka Munk function was employed to estimate the band gap value which was seen lying within 3.58 to 3.64 eV. Further the antibacterial activity of ZnS is investigated and it is found to be an antibacterial agent of Escherichia coli and staphylococcus aurous, further it can be employed as an antimicrobial agent for prohibiting implant linked infections.
Summary The loss of chloride ion from the title complexes resulted in the predominant formation of the chelated amino-alcohol productscis-[Co(en)2(NH2CH2CH(X)O/H)]2+/3+ (X=H or Me). The kinetics of chloride release were investigated in aqueous ethylene glycol (EG) media (0 to 80% by wt of EG) at 40°–65°C in acidic media and at 20°–35°C in basic media. The rate constants decreased linearly with increasing mol fraction of the cosolvent. The plots of log kversus D
s–1
(Ss=bulk dielectric constant, k=first order or second order rate constants) were essentially linear with negative slopes for the reactions in an acidic medium, and tended to be curved for the base catalysed reactions. The activation enthalpies and entropiesversus XEG (XEG=mol fraction of EG) plots indicated extrema which might be associated with the effects of the solvent structural changes on these thermodynamic parameters. The observed solvent isotope effect
at 50°C, [HClO4]=0.010 mol dm–3 for Cl– release was lower than the value for the aquation ofcis-[Co(en)2(alkylamine)Cl]2+ complexes
reported in the literature. This is consistent with the lack of direct solvent molecule participation in the actual act of substitution at the cobalt(III) centre, as expected for a true intramolecular reaction.Part-11: A. C. Dash and J. Pradhan,Ind. J. Chem.,29A, 167 (1990). 相似文献