Sorption of 241Am by Aspergillus nigerspore and hyphae

Biosorption of ²⁴¹Am by a fungus A. niger, including the spore and hyphae, was investigated. The preliminary results showed that the adsorption of ²⁴¹Am by the microorganism was efficient. More than 96% of the total ²⁴¹Am could be removed from ²⁴¹Am solutions of 5.6-111 MBq/l (C _o) by spore and hyphaeof A. niger, with adsorbed ²⁴¹Am metal (Q) of 7.2-142.4 MBq/g biomass, and 5.2-106.5 MBq/g, respectively. The biosorption equilibrium was achieved within 1 hour and the optimum pH range was pH 1-3. No obvious effects on ²⁴¹Am adsorption by the fungus were observed at 10-45 °C, or in solutions containing Au³⁺ or Ag⁺, even 2000 times above the ²⁴¹Am concentration. The ²⁴¹Am biosorption by the fungus obeys the Freundlich adsorption equation. There was no significant difference between the adsorption behavior of A. nigerspore and hyphae. This revised version was published online in July 2006 with corrections to the Cover Date.     

A zwitterion of 1,5‐bis­(2‐hydroxy­benzamido)‐3‐aza­pentane: a two‐dimensional hydrogen‐bonding network involving dimers

The title compound, 2‐{N‐[2‐(2‐hydroxy­benzamido)ethyl­ammonio­ethyl]amino­carbon­yl}phenolate, C₁₈H₂₁N₃O₄, crystallizes in a zwitterionic form as a result of inter­molecular proton transfer and possesses a negatively charged phenolate group and a protonated amino group. The 2‐hydroxy­benzamide and 2‐(amino­carbonyl)­phenolate moieties attached to the two ends of the C—C—N—C—C backbone adopt a cis conformation in relation to this backbone. All N‐ and O‐bound H atoms are involved in hydrogen‐bond formation; the zwitterions are first linked into head‐to‐tail dimers, which are further organized into a two‐dimensional network parallel to the crystallographic bc plane.     

High-throughput semi-automated 96-well liquid/liquid extraction and liquid chromatography/mass spectrometric analysis of everolimus (RAD 001) and cyclosporin a (CsA) in whole blood

A semi-automated high-throughput liquid/liquid extraction (LLE) assay was developed for RAD001 and cyclosporin A (CsA) in human blood. After addition of internal standard and ammonium hydroxide, samples were extracted twice with methyl tert-butyl ether (MTBE). The organic extract was evaporated to dryness and reconstituted in mobile phase. Where possible, sample transfer and LLE steps were automated using a Tomtec Quadra 96 workstation. Samples were analyzed using ESI-LC/MS/MS employing the transitions of ([M + NH(4)](+) --> [M + H](+)) for CsA and ([M + NH(4)](+) --> [M + H-(CH(3)OH + H(2)O)](+)) for RAD001, under isocratic chromatographic conditions (75:25, (v/v), acetonitrile/20 mM ammonium acetate) with a run time of 3.6 min. A lower limit of quantitation (LLOQ) of 0.368 ng/mL and 5.23 ng/mL was achieved for RAD001 and CsA, respectively, using a sample volume of 0.3 mL for the analysis. The method was validated over a 3-day period and the resulting calibration curves had a correlation coefficient >0.99 over the concentration range 0.368 to 409 ng/mL and 5.24 to 1748 ng/mL for RAD001 and CsA, respectively. The inter-day coefficient of variation (CV) was less than 15% at the LLOQ for both compounds. The method was applied to the analysis of clinical samples. Under normal working conditions four 96-well plates could be extracted and LC/MS analysis completed in less than 28 h. A marked improvement in sample throughput efficiency was realized with this LLE method when compared to existing solid phase extraction (SPE) methods which deal with both RAD001 and CsA.     

A study of the polarographic behaviour of meso-tetra(4-trimethylammoniumphenyl)porphine and its copper and magnesium complexes and its analytical applications

The investigation of the electrochemical reduction and the adsorption of meso-tetra(4-trimethylammoniumphenyl)porphine (T(4-TMAP)P) at a mercury electrode in alkaline solution shows that the overall reduction involves three two-electron steps, of which the first step is reversible and the latter two are irreversible. In addition, T(4-TMAP)P and its metal complexes of Cu(II) and Mg(II) can be strongly adsorbed on the surface of a mercury electrode. The adsorption phenomena have been utilized as a preconcentration step for the determination of trace amounts of the two ions by single sweep polarography. For copper, the detection limit is 1 × 10^–8 mol dm^–3, for magnesium, 1 × 10^–7 mol dm^–3, the latter being limited by the reagent blank. The proposed method was applied to the determination of Cu and Mg in various types of samples (chemicals, hair and liver tissues) with satisfactory results.     

胆汁酸的薄层层析——数理统计法用于层析溶剂系统的选择

本文选择氯仿、乙醇、乙酸乙酯、醋酸和水等五种溶剂作为胆汁酸薄层层析的展开剂,采用正交设计法[L_(16)(4~5)]安排实验,对胆固醇、胆酸、脱氧胆酸、甘氨胆酸、甘氨脱氧胆酸、牛磺胆酸、牛磺脱氧胆酸和卵磷脂等八种化合物的R_f值及层析谱斑点的集中情况,用直观分析和方差分析法处理,得到了单向一次薄层层析全部分离胆汁的溶剂系统,较文献报道方法为佳。     

Biosorption of americium-241 by Saccharomyces cerevisiae

The biosorption of radionuclide ²⁴¹Am from solution by Saccharomyces cerevisiae (S. cerevisiae), and the effects of experimental conditions on the adsorption were investigated. The preliminary results showed thatS. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total ²⁴¹Am could be removed by S. cerevisiae of 2.1 g/l (dry weight) from ²⁴¹Am solutions of 17.54–4386.0 mg/l (2.22 MBq/l–555 MBq/l) with adsorption capacities of 7.45–1880.0 mg/g biomass (dry weight) (0.94 MBq/g–237.9 MBq/g). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1–3. No significant differences on ²⁴¹Am adsorption were observed at 10–45 °C, or in solutions containing Au³⁺ or Ag⁺, even 2000 times above ²⁴¹Am concentration. The relationship between concentrations and adsorption capacities of ²⁴¹Am indicated the biosorption process should be described by the Freundlich adsorption isotherm.     

Modeling η5‐C5Me4SiMe3 with η3‐C3H5 for DFT study of a tetranuclear yttrium polyhydrido complex [(η5‐C5Me4SiMe3)YH2]4

π‐Allyl (η³‐C₃H₅), a four‐electron donor, was used as a ligand model to replace η⁵‐C₅Me₄SiMe₃ in DFT calculations on the tetranuclear yttrium polyhydrido complex (η⁵‐C₅Me₄SiMe₃)₄Y₄H₈ containing a Y₄H₈ tetrahedral core structure, which may separate the four π‐allyl groups and hence suppress the allyl ligand coupling during the computation. In terms of the calculated core geometry, isomerization energy barrier, charge population, and frontier orbital features of the complex, the η³‐C₃H₅ ligand model is comparable to η⁵‐C₅H₅. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Synthesis and optical resolution of a series of inherently chiral calix[4]crowns with cone and partial cone conformations

A series of inherently chiral calix[4]arenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)-BINOL to form diastereomers which, in most cases, could be separated by preparative TLC, or more desirably, by column chromatography on silica gel (diastereomeric excess >99 % based on HPLC analysis). Seven enantiopure antipodes of inherently chiral calix[4]crowns were obtained after hydrolysis. It has been found that both the size of the crown moiety and alkylation of the last phenolic hydroxy group (accompanied with or without a change in the conformation) affect the separation of the diastereomers.     

The synthesis of substituted [1]benzothieno[2,3-c]quinolines and their N-methyl quaternary salts

Four substituted [1]benzothieno[2,3-c]quinolines 14a-14d were prepared by photocyclization of the appropriate carboxamides 8a-8d to the corresponding [1]benzothieno[2,3-c]quinolin-6(5H)-ones 12a-12d followed by chlorination to 6-chloro[1]benzothieno[2,3-c]quinolines 13a-13d and dechlorination resulting in the title compounds. Treatment of 14a-14d with iodomethane furnished the corresponding N-methyl quaternary salts 5a-5d .     

Physisorption of molecular oxygen on C60 thin films

The interaction of oxygen molecules with a fullerene surface has been studied using high resolution electron energy loss spectroscopy and temperature programmed desorption. Vibrational excitation of the adsorbed oxygen is observed at 190 meV, an energy value comparable with that for molecular oxygen in the gas phase. We take this to indicate physisorption of molecular oxygen on the C(60) surface. Thermal desorption results also show that the bonding of oxygen molecules to the C(60) overlayer is comparable to that on a graphite surface. A detailed study of the energy dependence of the vibrational excitation reveals an inelastic electron resonance scattering process. The angular dependence of the resonant vibrational excitation exhibits features distinctively different from those for molecular oxygen physisorbed on the related graphite surface, at a comparable coverage. One possible reason is that the corrugated surface potential, due to the curvature of the C(60) molecules, promotes the preferential ordering of the physisorbed oxygen molecules perpendicular to the surface plane of the C(60) overlayer.