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81.
82.
This paper describes a novel strategy for actinide separation by extraction chromatography with Np(III) valence adjustment. Neptunium(IV) was reduced to Np(III) using Cr(II) and then selectively separated from uranium (IV) on a TEVA resin. After elution, Np(III) was retained on a DGA resin in order to remove any detrimental chromium impurities. Neptunium(III) formation was demonstrated by the complete and selective elution of Np from TEVA resin (99 ± 7%) in less than 12 mL of 9 M HCl from U(IV) (0.7 ± 0.7%). It was determined by UV–visible and kinetic studies that Cr(II) was the only species responsible for the elution of Np(IV) as Np(III) and that the Cr(II) solution could be prepared from 2 to 30 min before its use without the need of complex degassing systems to prevent the oxidation of Np(III) by oxygen. The methodology proposed here with TEVA/DGA resins provides removal of Cr(III) impurities produced at high decontamination factors (2.8 × 103 and 7.3 × 104 respectively). 相似文献
83.
Less RJ Wilson TC McPartlin M Wood PT Wright DS 《Chemical communications (Cambridge, England)》2011,47(36):10007-10009
The ready formation of a range of transition metal complexes of the pentacyanocyclopentadienide anion via ligand transfer reactions employing Na[C(5)(CN)(5)] indicates that the [C(5)(CN)(5)](-) anion has an extensive transition metal coordination chemistry and is not such a weakly coordinating anion. 相似文献
84.
Freudenmann D Wolf S Wolff M Feldmann C 《Angewandte Chemie (International ed. in English)》2011,50(47):11050-11060
Ionic liquids are credited with a number of unusual properties. These include a low vapor pressure, a wide liquid‐phase range, weakly coordinating properties, and a high thermal/chemical stability. These properties are certainly of great interest for inorganic synthesis and the creation of novel inorganic compounds. On the other hand, the synthesis repertoire for preparing inorganic compounds has always been broad, ranging from syntheses in solutions and melts to solid‐state reactions, and from crystal growth in the gas phase to high‐pressure syntheses. What new aspects can ionic liquids then add to the synthesis of inorganic compounds? This Minireview uses some early examples to show that the use of ionic liquids indeed provides access to unusual inorganic compounds. 相似文献
85.
Use of atmospheric pressure solids analysis probe time‐of‐flight mass spectrometry to screen for plasticisers in gaskets used in contact with foods 下载免费PDF全文
86.
Torsten Roth Vladislav Vasilenko Callum G. M. Benson Hubert Wadepohl Dominic S. Wright Lutz H. Gade 《Chemical science》2015,6(4):2506-2510
A simple, “click” synthetic approach to a new type of hybrid phosph(III)azane/NHC system is described. The presence of the phosphazane P2N2 ring unit, with P atoms flanking the NCN fragment and with this ring perpendicular to the binding site of the NHC, provides unique opportunities for modifying the electronic and steric character of these carbenes. 相似文献
87.
Dodds F García F Kowenicki RA Parsons SP McPartlin M Wright DS 《Dalton transactions (Cambridge, England : 2003)》2006,(35):4235-4243
The condensation reactions of the dimer [ClP(micro-NR)](2) with organic diacids [LL(H)(2)], possessing linear orientations of their organic groups, result in the formation of phospha(III)zane macrocyles of the type [{P(mu-NR)}(2)(LL)](n) of various sizes. The series of macrocycles [{P(mu-N(t)Bu)}(2){1,5-(NH)(2)C(10)H(6)}](3), [{P(mu-NCy)}(2)(1,5-O(2)C(10)H(6))](n) [n = 3; n = 4], [{P(mu-N(t)Bu)}(2){1,4-(NH)(2)C(6)H(4)}](4), [{P(mu-N(t)Bu)}(2)(1,4-O(2)C(6)H(4))], [{P(mu-NCy)}(2)(1,4-O(2)C(6)H(4))](3) and [{P(mu-N(t)Bu)}(2){(NH)C(6)H(4)OC(6)H(4)(NH)}](2) can be related to classical organic frameworks, like calixarenes. 相似文献
88.
Boere IA Robinson DJ de Bruijn HS Kluin J Tilanus HW Sterenborg HJ de Bruin RW 《Photochemistry and photobiology》2006,82(6):1638-1644
Barrett's esophagus (BE) can experimentally be treated with 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT), in which ALA, the precursor of the endogenous photosensitizer protoporphyrin IX (PpIX) and subsequent irradiation with laser light are applied to destroy the (pre)malignant tissue. Accurate dosimetry is critical for successful ALA-PDT. Here, in vivo dosimetry and kinetics of PpIX fluorescence photobleaching were studied in a rat model of BE. The fluence and fluence rate were standardized in vivo and PpIX fluorescence was measured simultaneously at the esophageal wall during ALA-PDT and plotted against the delivered fluence rather than time. Rats with BE were administered 200 mg kg(-1) ALA (n = 17) or served as control (n = 4). Animals were irradiated with 633 nm laser light at a measured fluence rate of 75 mW cm(-2) and a fluence of 54 J cm(-2). Large differences were observed in the kinetics of PpIX fluorescence photobleaching in different animals. High PpIX fluorescence photobleaching rates corresponded with tissue ablation, whereas low rates corresponded with no damage to the epithelium. Attempts to influence tissue oxygenation by varying balloon pressure and ventilation were shown not to be directly responsible for the differences in effect. In conclusion, in vivo dosimetry is feasible in heterogeneous conditions such as BE, and PpIX fluorescence photobleaching is useful to predict the tissue response to ALA-PDT. 相似文献
89.
Mono‐, di‐ and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance 下载免费PDF全文
Chris Knappy Daniela Barillà James Chong Dominic Hodgson Hugh Morgan Muhammad Suleman Christine Tan Peng Yao Brendan Keely 《Journal of mass spectrometry : JMS》2015,50(12):1420-1432
Higher homologues of widely reported C86 isoprenoid diglycerol tetraether lipid cores, containing 0–6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography‐tandem mass spectrometry confirms that the additional carbon atoms in the C87‐88 homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl (‘H‐shaped’) tetraethers containing C40‐42 or C81‐82 hydrocarbons, respectively, many representing novel compounds. Gas chromatography‐mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C40 chains are biphytanes and the C41 chains 13‐methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di‐ and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C87‐89 tetraethers highlight their potential as complementary biomarkers for archaea in natural environments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
90.
Kruijt B de Bruijn HS van der Ploeg-van den Heuvel A de Bruin RW Sterenborg HJ Amelink A Robinson DJ 《Photochemistry and photobiology》2008,84(6):1515-1527
The presence of phased protoporphyrin IX (PpIX) bleach kinetics has been shown to correlate with esophageal response to 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) in animal models. Here we confirm the existence of phased PpIX photobleaching by increasing the temporal resolution of the fluorescence measurements using the therapeutic illumination and long wavelength fluorescence detection. Furthermore fluorescence differential pathlength spectroscopy (FDPS) was incorporated to provide information on the effects of PpIX and tissue oxygenation distribution on the PpIX bleach kinetics during illumination. ALA at a dose of 200 mg kg(-1) was orally administered to 15 rats, five rats served as control animals. PDT was performed at an in situ measured fluence rate of 75 mW cm(-2) using a total fluence of 54 J cm(-2). Forty-eight hours after PDT the esophagus was excised and histologically examined for PDT-induced damage. Fluence rate and PpIX photobleaching at 705 nm were monitored during therapeutic illumination with the same isotropic probe. A new method, FDPS, was used for superficial measurement on saturation, blood volume, scattering characteristics and PpIX fluorescence. Results showed two-phased PpIX photobleaching that was not related to a (systematic) change in esophageal oxygenation but was associated with an increase in average blood volume. PpIX fluorescence photobleaching measured using FDPS, in which fluorescence signals are only acquired from the superficial layers of the esophagus, showed lower rates of photobleaching and no distinct phases. No clear correlation between two-phased photobleaching and histologic tissue response was found. This study demonstrates the feasibility of measuring fluence rate, PpIX fluorescence and FDPS during PDT in the esophagus. We conclude that the spatial distribution of PpIX significantly influences the kinetics of photobleaching and that there is a complex interrelationship between the distribution of PpIX and the supply of oxygen to the illuminated tissue volume. 相似文献