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1.
Grace‐Ann M. Lobo Sneha A. Chitre Spandan M. Rathod Robert B. Smith Ray Leslie Callum Livingstone James Davis 《Electroanalysis》2007,19(24):2523-2528
The exploitation of 2‐bromo‐1,4‐naphthoquinone (NQBr) as a selective redox label for the determination of reduced thiol functionalities (RSH) has been investigated. The system is selective for RSH functionality, giving distinct voltammetric signals for glutathione and cysteine but can also be adapted for broad spectrum thiol detection. Ion chromatographic protocols based on conductimetric detection enable total RSH analysis (protein and monomolecular moieties) within human plasma. Bromide released through the reaction can be easily quantified and integrated within normal IC measurements. The efficacy of the approach has been assessed and the response validated through comparison with the standard colorimetric technique. 相似文献
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The use of chiral secondary amines containing only one branched substituent has been shown to give optimal yields and stereoselectivities in the preparation of α-amino acids using the Petasis reaction. While the use of chiral primary amines generally gives products in low to moderate diastereoselectivity, chiral secondary amines generally give products in >95:5 diastereoselectivity. Additionally, the use of amines with two chiral (and by definition, branched) N-alkyl substituents results in significantly reduced yields with respect to to secondary amines with one or no branched N-alkyl substituents. 相似文献
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The setting of analytical quality specifications in laboratory medicine has attracted attention for many years. Over time,
many strategies were advocated and all had advantages and disadvantages. In the final decade of the last millennium, considerable
confusion existed on how to define analytical quality specifications correctly and how to apply them in everyday practice.
This led to wide professional interest. In 1999, a consensus conference sponsored by IUPAC, IFCC and WHO was held in Stockholm
on “Strategies to Set Global Analytical Quality Specifications in Laboratory Medicine”. The consensus set useful and well-documented
strategies for the setting of analytical quality specifications into a hierarchy with the best strategy at the highest level,
namely, (1) Evaluation of the effect of analytical performance on clinical outcomes in specific clinical situations, (2) Evaluation
of the effect of analytical performance on clinical decisions in general, (3) Published professional recommendations, (4)
Performance goals set by regulatory bodies and EQAS organisers, and (5) Goals based on the current state of the art. Much success has been achieved since the promulgation of the statement with the approach being adopted by many in laboratory
medicine for a very wide variety of purposes, particularly in quality management. However, there is a requirement for additional
investigation of, inter alia, quality specifications for examinations done on measurements performed on ordinal and nominal scales, pre-analytical factors
and matrix effects, examinations done as POCT, target values of control materials, and ways in which analytical quality specifications
can be used both to set what is the optimum performance and as a tool for assessment of everyday practice. 相似文献
5.
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
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Belmessieri D Joannesse C Woods PA MacGregor C Jones C Campbell CD Johnston CP Duguet N Concellón C Bragg RA Smith AD 《Organic & biomolecular chemistry》2011,9(2):559-570
The catalytic activity and enantioselectivity in the kinetic resolution of (±)-1-naphthylethanol with a range of structurally related 3,4-dihydropyrimido[2,1-b]benzothiazole-based catalysts is examined. Of the isothiourea catalysts screened, (2S,3R)-2-phenyl-3-isopropyl substitution proved optimal, giving good levels of selectivity in the kinetic resolution of a number of secondary alcohols (S values up to >100 at ~50% conversion). Low catalyst loadings (0.10-0.25 mol%) of the optimal isothiourea can be used to generate enantiopure alcohols (>99% ee) in good yields. 相似文献
8.
The accuracy of tomographic particle image velocimetry for measurements of a turbulent boundary layer 总被引:1,自引:0,他引:1
Callum Atkinson Sebastien Coudert Jean-Marc Foucaut Michel Stanislas Julio Soria 《Experiments in fluids》2011,50(4):1031-1056
To investigate the accuracy of tomographic particle image velocimetry (Tomo-PIV) for turbulent boundary layer measurements,
a series of synthetic image-based simulations and practical experiments are performed on a high Reynolds number turbulent
boundary layer at Reθ = 7,800. Two different approaches to Tomo-PIV are examined using a full-volume slab measurement and a thin-volume “fat” light
sheet approach. Tomographic reconstruction is performed using both the standard MART technique and the more efficient MLOS-SMART
approach, showing a 10-time increase in processing speed. Random and bias errors are quantified under the influence of the
near-wall velocity gradient, reconstruction method, ghost particles, seeding density and volume thickness, using synthetic
images. Experimental Tomo-PIV results are compared with hot-wire measurements and errors are examined in terms of the measured
mean and fluctuating profiles, probability density functions of the fluctuations, distributions of fluctuating divergence
through the volume and velocity power spectra. Velocity gradients have a large effect on errors near the wall and also increase
the errors associated with ghost particles, which convect at mean velocities through the volume thickness. Tomo-PIV provides
accurate experimental measurements at low wave numbers; however, reconstruction introduces high noise levels that reduces
the effective spatial resolution. A thinner volume is shown to provide a higher measurement accuracy at the expense of the
measurement domain, albeit still at a lower effective spatial resolution than planar and Stereo-PIV. 相似文献
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Dr. Thais F. Abelha Dr. Graeme Morris Dr. Sandro M. Lima Dr. Luis H. C. Andrade Dr. Andrew J. McLean Prof. Cameron Alexander Dr. Jesus Calvo-Castro Dr. Callum J. McHugh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(14):3173-3180
Development of novel bioimaging materials that exhibit organelle specific accumulation continues to be at the forefront of research interests and efforts. Among the various subcellular organelles, mitochondria, which are found in the cytoplasm of eukaryotic cells, are of particular interest in relation to their vital function. To date, most molecular probes that target mitochondria utilise delocalised lipophilic cations such as triphenylphosphonium and pyridinium. However, the use of such charged motifs is known to be detrimental to the working function of the mitochondrial transmembrane potential and there remains a strong case for development of neutral mitochondrial fluorescent probes. Herein, we demonstrate for the first time the exploitation of diketopyrrolopyrrole-based chemistries for the realisation of a neutral fluorescent probe that exhibits organelle specific accumulation within the mitochondria at the nanomolar level. The synthesised probe, which bears a neutral triphenylphosphine oxide moiety, exhibits a large Stokes shift and high fluorescence quantum yield in water, both highly sought-after properties in the development of bioimaging agents. In vitro studies reveal no interference with cell metabolism when tested for the human MCF7 breast cancer cell and nanomolar subcellular organelle colocalisation with commercially available mitochondrial staining agent Mitotracker Red. In light of its novelty, neutral structure and the preferential accumulation at nanomolar concentrations we anticipate this work to be of significant interest for the increasingly larger community devoted to the realisation of neutral mitochondrial selective systems and more widely to those engaged in the rational development of superior organic architectures in the biological field. 相似文献