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81.
The on-chip measurement of absorbing species has proven to be challenging, particularly with respect to the sample pathlengths available in a miniaturised system. This paper demonstrates how the principles of total internal reflection can be utilised to form a liquid-core waveguide along a single microfluidic channel, increasing the sampling pathlength to 5 mm while maintaining a detection volume of < or = 1 microL. This was achieved using the Teflon fluoropolymers PTFE, FEP and AF as cladding for the liquid-core waveguide. In conjunction with a 3D chip architecture, the use of the liquid-core waveguide enables more efficient use of the probing light beam along with easy and effective coupling of the source, microfluidic chip and the detection system. The confirmation that waveguiding was occurring was successfully demonstrated and the subsequent spectrophotometric analysis of crystal violet provided a linear calibration with reproducibility (< 2.4% RSD) and limits of detection (< 1.3 microM), comparable to absorbance measurements made with a standard UV-Vis spectrophotometer. 相似文献
82.
83.
An efficient and practical synthesis of the title compounds is described. The novel route is based on earlier results and uses (±)-5-hydroxy-9,9-o-phenylenedioxy-decanoic acid lactone as the starting material. The results demonstrate the usefulness of pyrocatechol for the protection of an aliphatic ketone. 相似文献
84.
85.
Niamh Holland Patrick Duggan Eleanor Owens Wayne Cummins June Frisby Helen Hughes Peter McLoughlin 《Analytical and bioanalytical chemistry》2008,391(4):1245-1253
A powerful method utilising direct probe thermal desorption GC–MS is presented for the study of molecularly imprinted polymers
(MIPs). A series of 2-aminopyridine (2-apy)-imprinted methacrylic acid–ethyleneglycol dimethacrylate (MAA–EGDMA) copolymers
were prepared under identical conditions but with varying amounts of EGDMA (crosslinking monomer). The use of appropriate
temperature programmes permitted template removal, and the subsequent assessment of polymer affinity and specificity, all
of which were found to be dependent on polymer composition and morphology. The system was sufficiently sensitive to identify
a specific response of imprinted polymers over nonimprinted counterparts. Correlations were found to exist between thermal
desorption analysis and solution phase binding, which was assessed by UV spectroscopy, where specificity was found to diminish
with decreasing EGDMA concentration. This was attributed to the increased number of free carboxyl groups in those polymers
containing a lower percentage of EGDMA. Thermal desorption profiles obtained for the analyte were found to be unaffected by
the physical and chemical properties of the solvent used for analyte reloading.
An erratum to this article can be found at 相似文献
86.
(R)-2-Phenylglycine ethyl ester was found to be a cheap and effective auxiliary for the preparation of aliphatic α,α-difluoro-β(3)-amino esters via a Reformatsky reaction performed under sonication conditions. The products were obtained in good to high yield and ≥96:4 dr, thus providing a new stereoselective route to this under-represented class of compounds. A facile one-pot removal of the phenylglycine moiety and concomitant Boc protection subsequently afforded the corresponding Boc-protected β(3)-amino esters in excellent yield. 相似文献
87.
Liu Y D'Arceuil H He J Duggan M Gonzalez G Pryor J de Crespigny A 《Magnetic resonance imaging》2006,24(8):1069-1075
This article presents a warping technique for correcting brain tissue distortion on magnetic resonance imaging (MRI) scans due to stroke lesion growth and for mapping MRI scans to histological sections. Meshes are imposed upon the images for feature specification, and these features are exactly matched in the different images to be mapped, while the other voxels are matched by interpolation. This technique was tested on serial MR images and histological sections that were acquired in a nonhuman primate model of stroke. This technique was able to deliver satisfactory warping results. It is simple and robust and can be utilized in many applications for comparison of multimodality medical images and histological sections. 相似文献