二次电沉积法从~(90)Sr母液中分离医用~(90)Y的研究

研究了以0.15 mol/L的NH4Cl为底液,在自行设计的电解池中90Sr母液中电沉积分离医用的90Y.控制阴极电流密度为0.6A/cm2,电沉积40 min后,用0.1 mol/L的热盐酸洗脱后再次电沉积后得到医用90Y,二次电沉积后90Y与90Sr的分离系数大于1×106,90Y的洗脱收率大于70%.     

Development of technique for synthesis of methyl(β-oxyethyl) sulfide by the reaction of ethylene oxide with methyl mercaptan

Reaction of ethylene oxide with methyl mercaptan in the presence of a catalyst, a solution of potassium hydroxide in methyl(β-oxyethyl) sulfide, was studied. Various technological procedures for synthesis of methyl(β-oxyethyl) sulfide were analyzed. The process conditions providing a 98–99% conversion of the starting reagents at a selectivity of 97–98% were suggested.     

Crystal structure analysis of β-tricalcium phosphate Ca3(PO4)2 by neutron powder diffraction

The crystal structure of sintered β-tricalcium phosphate, Ca₃(PO₄)₂, was refined using a high-resolution neutron powder diffraction data and the Rietveld method. This material was confirmed to have a rhombohedral structure (space group R3c, Z=21). Unit-cell parameters with higher precision (a=b=10.4352(2) Å, c=37.4029(5) Å, α=β=90°, and γ=120° in the hexagonal setting) and positional parameters for oxygen with equal precision were obtained by the neutron powder diffraction technique, compared with the single-crystal X-ray diffraction data by Dickens et al. (J. Solid State Chem. 10 (1974) 232). The site Ca(4) with atomic coordinates [0.0, 0.0, −0.0851(6)] was confirmed to be very different from the other four Ca sites: The position Ca(4) is three-fold coordinated with oxygen atoms, and has lower occupancy factor of 0.43(4), and a higher isotropic thermal parameter. On the contrary, each of the Ca(1), Ca(2), Ca(3), and Ca(5) is fully occupied by one Ca atom and these positions are coordinated with seven, eight, eight, and six oxygen atoms, respectively. The bond valence sums of Ca(4) and Ca(5) are lower (0.7) and higher (2.7), respectively, than the others (1.8-2.1).     

红酒中的~(87)Sr/~(86)Sr同位素比测定

研究了多接收电感耦合等离子体质谱(MC-ICP-MS)测定红酒样品中87Sr/86Sr同位素比的分析方法,并用建立的分离测定方法参加了欧洲参考物质与测量研究所(IRMM)组织的CCQM-P105国际比对,即红酒中87Sr/86Sr同位素比的分析比对.红酒样品经微波消解后,采用Dowex 50W×8树脂分离纯化锶,用MC-ICP-MS精确测定锶组分中的87Sr/86Sr同位素比,同时对测量结果的不确定度进行了分析和评定.     

Magnetic behaviour of the MTbF6 fluoroterbates (M=Cd,Ca, Sr, (α/β)-Ba)

Neutron powder diffraction has been performed on the MTbF₆ fluorides (M=Cd, Ca, Sr, (α/β)-Ba). Four of these fluorides (Cd, Ca, Sr, β-Ba) are built of a (pseudo-) tetragonal packing of [TbF₆]^2? chains and only differs by the chains relative orientations. Thus this series represents a valuable opportunity to evaluate the Tb⁴⁺-Tb⁴⁺ magnetic interactions. All the compounds displayed antiferromagnetic order (T_N=2.70 K (Cd), 2.15 K (Ca), 2.60 K (Sr), 2.10 K (β-Ba)), except for the α form of BaTbF₆. The crystal structure of this latter fluoroterbate has also been investigated by means of high-resolution neutron powder diffraction. From Neutron Powder Diffraction data, CdTbF₆ and β-BaTbF₆ magnetic structures were determined, together with the metamagnetic behaviour of β-BaTbF₆ as a function of an external magnetic field. A tentative phase diagram is then given for β-BaTbF₆. Advantage was taken of the polymorphism of the BaTbF₆ fluoroterbate to analyse, on the basis of topological parameters such as bond distances and angles, the magnetic behaviour of its α and β forms. It was shown that superexchange interactions are present in β-BaTbF₆, and that these interactions may also rule the magnetic behaviour of the other MTbF₆ (M=Ca, Sr, Cd) tetravalent terbium fluorides.     

Development of a N-acetyl-β-D-glucosaminidase (NAG) assay on a centrifugal lab-on-a-compact-disc (Lab-CD) platform

A centrifugal microfluidic platform, which is also known as lab-on-a-compact-disc (Lab-CD), was developed for use as a urinary N-acetyl-β-D-glucosaminidase (NAG) activity assay. In this work, Lab-CD design, centrifugal operations and analytical procedures were established. Automated liquid handling on Lab-CD processes, such as fluid transport, sample metering, mixing, and fluorescence detection are accomplished using a portable Lab-CD system. The linearity of the NAG assay using 4-methylumbelliferyl-N-acetyl-β-D-glucosaminide (4-MU-GlcNAc) was found to be acceptable in the range of 2.5 to 20 U L(-1); the relative standard deviations for the fluorescence intensity of eight samples (7.5 U L(-1)) was 6.4%. Clinical diagnostics is one of the most promising applications for Lab-CD technologies. All the benefits of miniaturization, such as reduced sample requirement, reduced reagent consumption and automation, are realized in this investigation.     

Development and application of a new solid-phase microextraction fiber by sol–gel technology on titanium wire

Novel solid-phase microextraction fibers were prepared based on sol–gel technique. Commonly used fused silica substrate was replaced by titanium wire which provided high strength and longer fiber life cycle. Titanium isopropoxide was employed as the precursor which provides a sol solution containing Ti–OH groups and shows more tendencies to the molecularly similar group on the substrate. Three different polymers, poly (dimethylsiloxane) (PDMS), poly(ethylenepropyleneglycol)-monobutyl ether (Ucon) and polyethylene glycol (PEG) were employed as coating polymer in preparing three different fibers. The applicability of these fibers was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Effects of different parameters such as fiber coating type, extraction condition, desorption condition were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.75–10 μg L⁻¹ (S/N = 3) and 1–20 μg L⁻¹ (S/N = 10) were respectively obtained. The method showed linearity in the range of 10–25,000 μg L⁻¹ with correlation coefficient of >0.99. The relative standard deviation was less than 8%.     

Binding of vitamin A byβ-cyclodextrin and heptakis(2,6-O-dimethyl)-β-cyclodextrin

Inclusion complexation of all-trans-retinol, retinal and retinoic acid with -cyclodextrin (-CD) and heptakis(2,6-O-dimethyl)--cyclodextrin (DM--CD) were investigated by means of UV-vis spectroscopy. The association constants (K _a) obtained for vitamin A with DM--CD is greater than with -CD. On the other hand, for the same host compoundK _a values of retinol, retinal and retinoic acid are very close to each other.     

Synthesis of (αR,βS)-epoxyketones by asymmetric epoxidation of chalcones with cinchona phase-transfer catalysts

An efficient method to synthetically produce optically enriched (αR,βS)-epoxyketones was developed using a quaternary ammonium salt derived from cinchona alkaloid as the chiral phase-transfer catalyst. (αR,βS)-Epoxyketones were prepared in high optical purities (91-99% ee) by the asymmetric epoxidation of 1,3-diarylenones with aqueous sodium hypochlorite in the presence of a hydrocinchonine-derived chiral phase-transfer catalyst bearing a 2,3,4-trifluorobenzyl group.     

Structural investigations of β-CaAlF5 by coupling powder XRD, NMR, EPR and spectroscopic parameter calculations

β-CaAlF₅ was synthesized by solid-state reaction. The precise structure was refined from X-ray powder diffraction data in the monoclinic space group P2₁/c with lattice constants , , , and β=109.91° (Z=4). The structure exhibits isolated chains of octahedra sharing opposite corners.¹⁹F and ²⁷Al solid state NMR spectra were recorded using MAS and SATRAS techniques. An EPR spectrum was recorded for β-CaAlF₅:Cr³⁺. The experimental spectra were simulated in order to extract the NMR and EPR parameter values. Five fluorine sites and one low symmetry aluminium site were found in agreement with the refined structure.These parameters were calculated using empirical and ab-initio methods. The agreement obtained between the calculated ¹⁹F chemical shift values, ²⁷Al quadrupolar parameters, Cr³⁺ EPR fine structure parameters and the experimental results demonstrates the complementarity of XRD, magnetic resonance experiments and theoretical methodologies.     

Kinetic resolution of hindered Morita-Baylis-Hillman adducts by Rh(I)-catalyzed asymmetric 1,4-addition/β-hydroxyelimination

A kinetic resolution of hindered Morita-Baylis-Hillman adducts has been successfully achieved in excellent selectivities via Rh(I)-catalyzed asymmetric 1,4-addition/β-hydroxyelimination with the use of a chiral sulfinamide/olefin hybrid ligand. This study provides a novel and efficient access to both optically active hindered highly functionalized alkenes and Morita-Baylis-Hillman adducts.     

Ternary surface complexes by the E(%)-pH curve method

A new method for the study of ternary surface complexes at liquid-solid interface,the E(%)-pH curve method,was proposed.Four types of E(%)-pH curves,namely,phenomenon of left-right shifts of S-shaped curve,V-shaped curve,monodirection shift curve and X-shaped curve,were discovered.Correspondingly,apart fromtype (Ⅰ) ternary surface complex -S-O-M-L and type (Ⅱ) ternary surface complex -S-L-M,a newtype of ternary surface complex -S-O-L-M was discovered.     

Sol–gel transitions of sodium montmorillonite dispersions by cationic end-capped poly(ethylene oxides) (surface modification of bentonites, IV)

Poly(ethylene oxides), PEO, end-capped with hexadecyl dimethylammonium, HDDMA⁺, and trimethylammonium hexyldimethylammonium, THA²⁺, changed distinctly the sol–gel transition of sodium montmorillonite dispersions. In the presence of HDDMA⁺-PEO 1,500 and 4,000, domains of sol with increased salt tolerance (c _k=550–1,000 mmol NaCl/l) were found at high polymer and low montmorillonite contents. The corresponding PEO of higher molar mass (20,000 and 35,000) led to extended fields of flocs. THA²⁺-PEO 1,500 formed attractive gels at polymer concentrations >2–5 g/l and montmorillonite contents >0.5%. These gels showed very high yield values. THA²⁺-PEO of higher molar mass acted as stabilizing agents. The salt tolerance was highest (300–750 mmol/l) in the presence of THA²⁺-PEO 20,000. The observed sol–gel diagrams reveal the interplay between polymer end-group fixation on the clay mineral particles, polymer conformation, and colloidal stabilization and destabilization mechanisms.

Growth and Spectral Characterization of Nd3+∶(Sr0.7Ca0.3)3Y(BO3)3 Crystal

A Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal with dimensions of 17×23 mm3 has been grown by the Czochralski method. The spectroscopic characterization of Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal was investigated. The polarized absorption cross-sections of Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal are 2.81×10-20 cm2 with full width at half maximum (FWHM) of 14 nm at 808 nm for σ-polarization and 2.04×10 -20 cm 2 with FWHM of 19 nm at 807 nm for σ-polarization, respectively. The polarized emission cross-sections of Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal are 12.2×10-20 cm2 at 1062 nm for the π-polarization and 13.6×10-20 cm2 at 1061 nm for the σ-polarization, respectively. After the Ca 2+ ion partly substitutes for Sr2+ ion in the Sr3Y(BO3)3 crystal to form the (Sr0.7Ca0.3)3Y(BO3)3 solid solution, it can improve the quantum efficiency of Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal. The quantum efficiency is 31.7%. These results may be regarded Nd3+ :(Sr0.7Ca0.3)3Y(BO3)3 crystal as a potential solid-state laser material.     

Adsorption of trace thorium(IV) from aqueous solution by mono-modified β-cyclodextrin polyrotaxane using response surface methodology (RSM)

The adsorption of thorium(IV) was studied using a novel supramolecular polyrotaxane based on β-cyclodextrin derivatives. The effects of pH, contact time, Th(IV) initial concentration and adsorbents dosage on the adsorption of thorium(IV) by polyrotaxane were optimized using Box–Behnken design of response surface methodology. Analysis of variance and correlation coefficients showed that the predicted model was consistent with the experimental data well. The adsorption best fitted to the Langmuir model indicated that the adsorption process happened on homogeneous surface. The thermodynamic parameters (?G ⁰ < 0, ?H ⁰ > 0, ?S ⁰ > 0) demonstrated that the adsorption of Th(IV) ions onto polyrotaxane was spontaneous and endothermic.     

Room temperature preparation of α-chloro-β,β-difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes

α-Chloro-β,β-difluorovinylzinc reagent [CF₂CClZnCl] was generated in 91% yield by the metallation of a THF solution of commercially available HCFC-133a (CF₃CH₂Cl) and zinc chloride at 15-20 °C using LDA as base. The corresponding reaction with Halothane™ (CF₃CHClBr) produced a poor yield of CF₂CClZnCl. The palladium catalyzed coupling reaction of the CF₂CClZnCl with aryl iodides under mild reaction conditions produced α-chloro-β,β-difluorostyrenes in 64-90% isolated yields. The stability of the intermediate CF₂CClLi and the nature of the zinc reagents are discussed.     

Highly enantioselective asymmetric hydrogenation of (E)-β,β-disubstituted α,β-unsaturated Weinreb amides catalyzed by Ir(I) complexes of SpinPhox ligands

The Ir(I) complexes of chiral spiro phosphino-oxazoline ligands (SpinPhox) have demonstrated good to excellent enantioselectivity in the asymmetric hydrogenation (AH) of a variety of (E)-β,β-disubstituted α,β-unsaturated N-methoxy-N-methylamides, affording the corresponding optically active Weinreb amides with up to 97% ee.