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51.
Functional MRI (fMRI) can detect blood oxygenation level dependent (BOLD) hemodynamic responses secondary to neuronal activity. The most commonly used method for detecting fMRI signals is the gradient-echo echo-planar imaging (EPI) technique because of its sensitivity and speed. However, it is generally believed that a significant portion of these signals arises from large veins, with additional contribution from the capillaries and parenchyma. Early experiments using diffusion-weighted gradient-echo EPI have suggested that intra-voxel incoherent motion (IVIM) weighting inherent in the sequence can selectively attenuate contributions from different vessels based on the differences in the mobility of the blood within them. In the present study, we used similar approach to characterize the apparent diffusion coefficient (ADC) distribution within the activated areas of BOLD contrast. It is shown that the voxel values of the ADCs obtained from this technique can infer various vascular contributions to the BOLD signal. 相似文献
52.
Okadaic acid (OA), a lipophilic phycotoxin is mainly produced by toxigenic dinoflagellates. The need to develop high performing methods for OA analysis able to improve the traditional ones is evident. In this work, a novel experimental methodology for label-free detection of OA was developed. Protein G magnetic beads (protein-G-MBs) modified gold electrode was used to immobilize anti-OA monoclonal antibody (anti-OA-MAb). Preliminary, colorimetric tests were performed in order to validate protein-G-MBs and anti-OA-MAb reaction. Electrochemical detection was carried out by differential pulse voltammetry in ferri/ferrocyanide solution. The limit of detection value obtained (0.5 μg L−1) validated the developed electrochemical immunosensor as a promising tool for routine use. The matrix effect and the recovery rate were also assessed with real samples, showing a good percentage of recovery. 相似文献
53.
Noiré M.H. Couston L. Douarre E. Pouyat D. Bouzon C. Marty P. 《Journal of Sol-Gel Science and Technology》2000,17(2):131-136
Nuclear fuel reprocessing requires high acidity levels that should be accurately and rapidly controlled in order to optimize extraction yields and process efficiency. A new optical fiber sensor based on a sol-gel film doped with an acid-sensitive indicator has been developed to improve remote and on-line monitoring.The organic molecule was physically incorporated in an acid-catalyzed sol-gel matrix and coated onto the core of a denuded optical fiber. The sensor response was evaluated in synthetic solutions of nitric acid, concentrations ranging from 1 to 10 mol · l–1. Changes in absorption properties and response characteristics of the sensor, when compared to the indicator in solution, have been discussed. Analytical performances of the sensor, i.e. sensitivity, response time, reversibility and repeatability are very encouraging for the on-line analysis. Viability of the sensor for process measurements depends on the stability which might be improved by a strict control of the sensitive film porosity. 相似文献
54.
55.
Al-Jawdah Ali Nabok Alexei Abu-Ali Hisham Catanante Gaelle Marty Jean-Louis Szekacs Andras 《Analytical and bioanalytical chemistry》2019,411(29):7717-7724
Analytical and Bioanalytical Chemistry - This work reports on further development of an optical biosensor for the in vitro detection of mycotoxins (in particular, aflatoxin B1) using a highly... 相似文献
56.
Pascal Sonnet Sophie Da NascimentoDanielle Marty Nicolas FranceschiniJean Guillon Jean-Daniel BrionJacques Rochette 《Tetrahedron letters》2003,44(16):3293-3296
The first synthesis of two segetalins B and G is described. The corresponding linear peptides were synthesized using standard automated continuous-flow SPPS methods. Ring closure positions were investigated for segetalin B. The best ring closure result was obtained between Val and Gly. 相似文献
57.
Non-aqueous reverse phase chromatography was used to optimize the separation of all-trans-α- and β-carotenes and their cis isomers extracted from dried carrots. The technique can easily be applied to routine assays. Optimization was carried out by modifying the concentrations of methylene chloride and acetonitrile, and by studying the influence of temperature on the capacity factors and selectivity. The effect of the type of C 18 stationary phase bonding (mono- and polyfunctional) on separation was also examined. The need for polymeric bonding on the stationary phase is stressed for the realization of the trans/cis isomer separation. 相似文献
58.
Marty C. Wilkes 《Journal of heterocyclic chemistry》1991,28(4):1163-1164
A new type of “azaphilic addition” reaction of methyl lithium to 3,6-bisalkylthio-1,2,4,5-tetrazines has been discovered. Methyl lithium adds at the tetrazine nitrogen of 1 affording 4 while nitrogen nucleophiles displace tetrazine alkylthio groups at carbon affording 3 . The structures of the N-alkyl products were determined by 1H- and 13C-nmr and uv experiments. Reversing the order of methyl lithium addition caused the formation of a bicyclic tetrazine 6 . Grignard reagents add in the same fashion as methyl lithium. 相似文献
59.
Peter Comba Donald A. House W. Gregory Jackson Werner Marty Helen Stoeckli-Evans Luc Zipper 《Helvetica chimica acta》1992,75(4):1130-1146
Oxygentation of aqueous solutions of CoIII in presence of stoichiometric amounts of N-(2-aminoethyl)ethane-1,2-diamine (dien) and 1,3-diaminopropan-2-ol (dapo) produces μ-peroxocobalt(III) dimers. Acid cleavage (HCI) yields mer-exo(H)-, mer-endo (H)-, unsym-fac-exo(OH)-, and unsym-fac-endo(OH)-[CoCl(dien)(dapo)]2+ ( A–D )(X = Cl), resp. and unsym-fac-[Co-(dien)(dapo-N,N′,O)]3+ ( G ). Isomer seperation was achieved by fractional crystallization as ZnCl and ClO salts and by ion-exchange chromatography. The corresponding bromo, azido, nitrito-O, nitro-N, thiocyanato, hydroxo, and aqua complexes were also synthesized. Optically resolved samples were prepared for chiral compounds, and the complexes were structurally characterized by X-ray analyses ($ \mathop {\it \Lambda} \limits^ \to $(?)436(CD) -A (X = N3)), ($ \mathop {\it \Delta} \limits^ \to $(?)436(CD) -B ). (X = N3), $ \mathop {\it \Delta} \limits^ \to $ (+)436(CD) -B by their chiroptical properties, and by 13C-NMR spectroscopy supported by 1H-NMR, IR, CD, and UV/VIS spectroscopy. $ \mathop {\it \Lambda} \limits^ \to $(?)436(CD)-mer-exo(H)-[Co(N3)(dien)(dapo)](hydrogen di-O-benzoyl-L-tartrate)2.4 H2O crystallizes in the orthorhombic space group P212121, a = 7.676(1) Å, b = 19.457(1) Å, c = 34.702(2) Å. $ \mathop {\it \Lambda} \limits^ \to $(?)436(CD)-mer-endo(H)-[Co(N3)(dien)(dapo)] (hydrogen di-O-benzoyl-L-tartrate)2.2.75 H2O crystallizes in the triclinic space group P1, a = 8.062(3) Å b = 10.296(1) Å, c = 15.056(2) Å, alpha = 80.55(1)°, β = 85.18(2)°, γ = 89.10(2)°. $ \mathop {\it \Delta} \limits^ \to $(+)436(CD)-mer-endo(H)-[Co(N3)(dien)(dapo)](hydrogen di-O-benzoyl-L-tartrate)2. 5.75 H2O crystallizes in the triclinic space group P1, a = 7.742(1) Å, b = 10.014(1) Å, c = 18.045(2) Å, α = 99.57(1)°, β = 92.87(1)°, γ = 102.56(1)°. The absolute configurations of the three cations were determined unambiguously. Interconversions of the various isomers and derivatives and structural, configurational, and spectroscopic aspects are discussed in detail. 相似文献
60.