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排序方式: 共有68条查询结果,搜索用时 31 毫秒
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Poon KW Lyng FM Knief P Howe O Meade AD Curtin JF Byrne HJ Vaughan J 《The Analyst》2012,137(8):1807-1814
Fibrinogen assays are commonly used as part of clinical screening tests to investigate haemorrhagic states, for detection of disseminated intravascular coagulation and as a predictor of a variety of cardiovascular events. The Clauss assay, which measures thrombin clotting time, is the most commonly used method for measuring fibrinogen levels. Nevertheless, inconsistencies are present in inter-manufacturer reagent sources, calibration standards and methodologies. Automated coagulation analysers, which measure changes in optical density during the prothrombin time (PT-Fg), have found use in many hospitals. However, the PT-Fg method is found to give falsely elevated values due to varying choices of calibrants, reagents and analysers. As an alternative, Raman spectroscopy has previously been applied to the analysis of blood and its various constituents to determine various analyte concentrations such as glucose, urea, triglycerides and cholesterol. In this study, Raman spectroscopy was investigated for its ability to accurately quantify fibrinogen concentration in blood plasma. Samples collected from 34 patients were analysed by Raman spectroscopy and the resultant spectra were fitted with a Partial Least Squares Regression model using target values obtained through a pre-calibrated Clauss fibrinogen assay. Various spectral pre-processing methods were utilised to prepare data to be entered into a calibration model. A root mean square error of prediction of 0.72 ± 0.05 g/L was achieved with as few as 25 spectra. In this pilot study, Raman spectroscopy has been demonstrated to be a robust technique providing rapid and reagent-free quantification of fibrinogen levels in blood plasma and a potential alternative to the Clauss assay. 相似文献
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Searching for cyclin-dependent kinase inhibitors using a new variant of the cope elimination 总被引:1,自引:0,他引:1
Griffin RJ Henderson A Curtin NJ Echalier A Endicott JA Hardcastle IR Newell DR Noble ME Wang LZ Golding BT 《Journal of the American Chemical Society》2006,128(18):6012-6013
beta-Piperidinoethylsulfides are oxidized by m-chloroperbenzoic acid to intermediates containing both N-oxide and sulfone functions. These undergo a Cope-type elimination to a vinylsulfone that can be captured by amines to afford beta-aminoethylsulfones. When a beta-aminoethylsulfone group is linked to the 4-position of a phenyl group attached at N-2 of O6-cyclohexylmethylguanine, the resulting derivatives are inhibitors of the cyclin-dependent kinase CDK2. One of the most potent inhibitors (IC50 = 45 nM) contained a N-3-hydroxypropyl group on the aminoethylsulfonyl substituent. The crystal structure of this inhibitor bound to CDK2/cyclin A was determined and shows an unusual network of hydrogen bonds. The synthetic methodology developed can be utilized in multiple-parallel format and has numerous potential applications in medicinal chemistry. 相似文献
35.
M.P. O’Day P. Nath W.A. Curtin 《Journal of the mechanics and physics of solids》2006,54(10):2214-2234
Interface delamination during indentation of micron-scale ceramic coatings on metal substrates is modeled using discrete dislocation (DD) plasticity to elucidate the relationships between delamination, substrate plasticity, interface adhesion, elastic mismatch, and film thickness. In the DD method, plasticity in the metal substrate occurs directly via the motion of dislocations, which are governed by a set of physically based constitutive rules for nucleation, motion and annihilation. A cohesive law with peak stress characterizes the traction-separation response of the metal/ceramic interface. The indenter is a rigid flat punch and plane strain deformation is assumed. A continuum plasticity model of the same problem is studied for comparison. For low interface strengths (e.g. ), DD and continuum plasticity results are quantitatively similar, with delamination being nearly independent of interface strength, and easier for thinner, lower-modulus films. For higher interface strengths (), continuum plasticity predicts no delamination up to very high loads while the DD model shows a smooth increase in the critical indentation force for delamination with increasing interface strength. Tensile delamination in the DD model is driven by the accumulation of dislocations, and their associated high stresses, at the interface upon unloading. The DD model is thus capable of predicting the nucleation of cracks, and its dependence on material parameters, in realms of realistic constitutive behavior and/or small length scales where conventional continuum plasticity fails. 相似文献
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Brian Curtin 《Designs, Codes and Cryptography》2005,34(2-3):241-248
It is well-known that a connected finite simple graph is regular if and only if the all-ones matrix spans an ideal of its adjacency algebra. We show that several other graph regularity conditions involving pairs and triples of vertices also have ideal theoretic characterizations in some appropriate algebras. 相似文献
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Margaret M. Curtin Carter N. Stewart McIntyre Hubert W. King Allan R. Pratt 《Journal of Non》1997,220(2-3):127-138
Slicate glass surfaces were observed over several weeks in normally humid laboratory air by atomic force microscopy. Auger spectroscopy and lateral force microscopy measurements were also made. Samples in the study include; vitreous quartz, bulk insulation glass, bulk and fibrous textile e-glass, and bulk container glass. Various features developed on these surfaces are consistent with patterns seen in crystal growth from supersaturated solution. Auger spectroscopy reveals the presence of chemically bound carbon and supports the hypothesis that these crystals are alkali and alkali earth carbonate species. The presence of these crystals is expected to affect the bonding of a coating to silicate surfaces. 相似文献
38.
The interaction of dislocations with grain boundaries (GBs) determines a number of important aspects of the mechanical performance of materials, including strengthening and fatigue resistance. Here, the coupled atomistic/discrete-dislocation (CADD) multiscale method, which couples a discrete dislocation continuum region to a fully atomistic region, is used to study screw-dislocations interacting with Σ3, Σ11, and Σ9 symmetric tilt boundaries in Al. The low-energy Σ3 and Σ11 boundaries absorb lattice dislocations and generate extrinsic grain boundary dislocations (GBDs). As multiple screw dislocations impinge on the GB, the GBDs form a pile-up along the GB and provide a back stress that requires increasing applied load to push the lattice dislocations into the GB. Dislocation transmission is never observed, even with large GBD pile-ups near the dislocation/GB intersection. Results are compared with experiments and previous, related simulations. The Σ9 grain boundary, composed from a more complex set of structural units, absorbs screw dislocations that remain localized, with no GBD formation. With increasing applied stress, new screw dislocations are then nucleated into the opposite grain from structural units in the GB that are nearby but not at the location where the original dislocation intersected the boundary. The detailed behaviour depends on the precise location of the incident dislocations and the extent of the pile-up. Transmission can occur on both Schmid and non-Schmid planes and can depend on the shear stresses on the GB plane. A continuum yield locus for transmission is formulated. In general, the overall dissociation and/or transmission behaviour is also determined by the Burgers vectors and associated steps of the primitive vectors of the grain boundary, and the criteria for dislocation transmission formulated by Lee et al . [Scripta Metall. 23 799 (1989); Phil. Mag. A 62 131 (1990); Metall. Trans. A 21 2437 (1990)] are extended to account for these factors. 相似文献
39.
Nicholas S. Labrum Gregory M. Curtin Prof. Dr. Elena Jakubikova Prof. Dr. Kenneth G. Caulton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9547-9555
Dimeric [CrL]2, where L is the conjugate base of bis-pyrazolyl pyridine, is evaluated for its ability to undergo inner sphere and outer sphere redox chemistry. It reacts with Cp2Fe+ to give [Cr4(HL)4(μ4-O)]2+, still containing divalent Cr. Reduction (KC8) of [CrL]2 by two electrons gives [K2(THF)3Cr3L3(μ3-O)], and by four electrons gives [K4(THF)10Cr2L2(μ-O)], each of which has scavenged (hydr)oxide from glass surface because of the electrophilicity of the underligated Cr. [K4(THF)10Cr2L2(μ-O)], is shown by comprehensive DFT calculations and analysis of intra-ligand bond lengths to contain a pyridyl radical L3− and CrII, illustrating that this pincer is proton-responsive, redox active, and a versatile donor to associated K+ ions here. The K+ electrophiles interact with electron-rich oxo, but do not significantly (>5 kcal mol−1) alter spin state energies. Inner sphere oxidation of [CrL]2 with a quinone gives [Cr2L2(semiquinone)2], while pre-reduced [CrL]22− reacts with quinone to give [K3(THF)3Cr2L2(catecholate)2(μ-OH)], a product of capture of two undercoordinated LCr(catecholate)1− by hydroxide. 相似文献
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