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71.
James N. OShea J. Ben Taylor Louise C. Mayor Janine C. Swarbrick Joachim Schnadt 《Surface science》2008,602(9):1693-1698
Here we present the characteristic signatures in X-ray absorption and photoemission spectroscopy for molecular damage in adsorbed monolayers of bi-isonicotinic acid on a rutile TiO2(1 1 0) surface. Bi-isonicotinic acid is the anchor ligand through which many important inorganic complexes are bound to the surface of TiO2 in dye-sensitized solar cells. The nature of the damage caused by excessive heating of the adsorbed monolayer is consistent with splitting the molecule into two adsorbed isonicotinic acid molecular fragments. The effect on the lowest unoccupied molecular orbitals (involved in electron transfer in the molecule) can be understood in terms of the adsorption geometry of the reaction products and their nearest neighbor interactions. 相似文献
72.
W. Wagner R. Rosenbusch E. Bergell C. Stiepel C. Bunge E. Louise E. Sauvage Marange und E. Philippot 《Fresenius' Journal of Analytical Chemistry》1932,87(7-8):309-311
Ohne Zusammenfassung 相似文献
73.
Rikard Westbom Sune Sporring Louise Cederberg Lars-Ola Linderoth Erland Bj?rklund 《Analytical sciences》2008,24(4):531-533
A selective pressurized liquid extraction procedure (SPLE) was developed for a fast determination of polychlorinated biphenyls in sediment. The final method was performed at 100 degrees C with heptane/dichloromethane (90:10, v/v) as extraction solvent for 2x5 min. Sulfuric acid impregnated silica was placed downstream of the sample in the extraction cell to remove interfering components. This simultaneous extraction/clean-up was performed in 20 min, with an average congener recovery of 92% compared to a classical 24 h Soxhlet methodology and 2 h of external manual clean-up. 相似文献
74.
Silvin P. Knight Louise Newman John D. OConnor James Davis Rose Anne Kenny Roman Romero-Ortuno 《Entropy (Basel, Switzerland)》2021,23(1)
In this cross-sectional study, the relationship between noninvasively measured neurocardiovascular signal entropy and physical frailty was explored in a sample of community-dwelling older adults from The Irish Longitudinal Study on Ageing (TILDA). The hypothesis under investigation was that dysfunction in the neurovascular and cardiovascular systems, as quantified by short-length signal complexity during a lying-to-stand test (active stand), could provide a marker for frailty. Frailty status (i.e., “non-frail”, “pre-frail”, and “frail”) was based on Fried’s criteria (i.e., exhaustion, unexplained weight loss, weakness, slowness, and low physical activity). Approximate entropy (ApEn) and sample entropy (SampEn) were calculated during resting (lying down), active standing, and recovery phases. There was continuously measured blood pressure/heart rate data from 2645 individuals (53.0% female) and frontal lobe tissue oxygenation data from 2225 participants (52.3% female); both samples had a mean (SD) age of 64.3 (7.7) years. Results revealed statistically significant associations between neurocardiovascular signal entropy and frailty status. Entropy differences between non-frail and pre-frail/frail were greater during resting state compared with standing and recovery phases. Compared with ApEn, SampEn seemed to have better discriminating power between non-frail and pre-frail/frail individuals. The quantification of entropy in short length neurocardiovascular signals could provide a clinically useful marker of the multiple physiological dysregulations that underlie physical frailty. 相似文献
75.
IR spectroscopy has been an important tool for studying detailed interactions of reactants and reaction-intermediates with catalyst surfaces. Studying reactions in water is, however, far from trivial, due to the excessive absorption of infrared light by water. One way to deal with this is the use of Attenuated Total Reflection spectroscopy (ATR-IR) minimizing the path length of infrared light through the water. Moreover, ATR-IR allows for a direct comparison of reactions in gas and water on the same sample, which bridges the gap between separate catalyst investigations in gas and liquid phase. This tutorial review describes recent progress in using ATR-IR for studying heterogeneous catalysts in water. An overview is given of the important aspects to be taken into account when using ATR-IR to study heterogeneous catalysts in liquid phase, like the procedure to prepare stable catalyst layers on the internal reflection element. As a case study, CO adsorption and oxidation on noble metal catalysts is investigated with ATR-IR in gas and water. The results show a large effect of water and pH on the adsorption and oxidation of CO on Pt/Al(2)O(3) and Pd/Al(2)O(3). From the results it is concluded that water affects the metal particle potential as well as the adsorbed CO molecule directly, resulting in higher oxidation rates in water compared to gas phase. Moreover, also pH influences the metal particle potential with a clear effect on the observed oxidation rates. Finally, the future outlook illustrates that ATR-IR spectroscopy holds great promise in the field of liquid phase heterogeneous catalysis. 相似文献
76.
Montserrat Cortina‐Puig Anastasia C. H. Scangas Zachary S. Marchese Silvana Andreescu Jean‐Louis Marty Carole Calas‐Blanchard 《Electroanalysis》2010,22(20):2429-2433
This paper describes the development of a xanthine oxidase/poly‐m‐phenylenediamine (XOD‐PPD)‐modified electrode. The biosensor was constructed by encapsulating XOD in a sol‐gel matrix deposited onto a platinum based screen‐printed electrode functionalized with a permselective PPD membrane. The hydrogen peroxide generated as a final product of the enzymatic reaction between the hypoxanthine and the XOD or by the spontaneous dismutation of superoxide radicals was selectively monitored at +700 mV. The use of a highly selective PPD layer blocked the nonspecific oxidation of other oxidizable molecules. Finally the biosensor was applied to the determination of the antioxidant capacity of acetylsalicylic acid. 相似文献
77.
Iodine-mediated cyclization of homoallyl amines at room temperature delivered cis-2,4-azetidine through a 4-exo trig cyclization. Isomerization of iodo-azetidines to cis-pyrrolidines could be achieved by heating, with complete stereocontrol. The relative stereochemistry of the iodo-azetidines and pyrrolidines was confirmed by NMR spectroscopy and X-ray crystallography. Further functionalization was achieved through nucleophilic displacement of iodine to deliver substituted azetidines and pyrrolidines. 1,2,3-Triazole-appended azetidines and pyrrolidines were also prepared. 相似文献
78.
We report on the rotational diffusion dynamics of the anionic chromophore resorufin in water and N-octyl-2-pyrrolidone (NOP) solutions as a function of solution electrolyte concentration. Our data show that resorufin exhibits a single exponential anisotropy decay in aqueous solutions containing up to 0.1 M lithium perchlorate (LiClO(4)). In contrast to the observed behavior of resorufin in pure NOP, where biexponential decay occurs, we also observe a single exponential anisotropy decay for resorufin in NOP with the addition of up to 0.1 M tetrabutylammonium bromide (TBAB) or tetraoctylammonium bromide (TOAB). For resorufin in NOP, the reorientation time constant increases with increasing electrolyte concentration, consistent with complexation between the resorufin anion and the electrolyte ammonium cation. We observe a qualitatively different trend in the aqueous resorufin solutions and understand these data for both solvent systems in the context of interactions between the chromophore and cationic species present. 相似文献
79.
Peter E.R. Blanchard Brianna R. Slater Ronald G. Cavell Arthur Mar Andrew P. Grosvenor 《Solid State Sciences》2010,12(1):50-58
The electronic structures of the quaternary oxyarsenides LaMAsO (M = Fe, Co, Ni) were examined with X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES). Interpretation of the metal 2p3/2 and arsenic 3d5/2 binding energies, as well as a satellite feature in the Co 2p XPS spectrum, suggests charges that are much less extreme than expected (i.e., not M2+ and As3?) because of the strong covalent character within the M–As bonds. As M is varied, the differing degrees of charge transfer from M to As atoms within these bonds are manifested by shifts in the As 3d5/2 binding energies and changes in the As K-edge intensities. This charge transfer is isolated within the [MAs] layer and does not influence the O 1s and La 3d XPS spectra. Fitting the experimental valence band spectra of these oxyarsenides LaMAsO yielded electron populations of states that support the formal charge assignment [La3+O2?][M2+As3?]. The mixed-metal series LaFe1?xM′xAsO (M′ = Co, Ni) was examined by XANES; analysis of the metal K- and L-edges, as well as of the Co 2p XPS satellite feature, revealed that no metal–metal charge transfer takes place. 相似文献
80.
Ludivine Louise‐Leriche Emilia Pǎunescu Géraldine Saint‐André Rachid Baati Anthony Romieu Alain Wagner Pierre‐Yves Renard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(11):3510-3523
A new pro‐fluorescent probe aimed at a HTS assay of scavengers is able to selectively and efficiently cleave the P? S bond of organophosphorus nerve agents and by this provides non‐toxic phosphonic acid has been designed and synthesised. The previously described pro‐fluorescent probes were based on a conventional activated P? Oaryl bond cleavage, whereas our approach uses a self‐immolative linker strategy that allows the detection of phosphonothioase activity with respect to a non‐activated P? Salkyl bond. Further, we have also developed and optimised a high‐throughput screening assay for the selection of decontaminants (chemical or biochemical scavengers) that could efficiently hydrolyse highly toxic V ‐type nerve agents. A preliminary screening, realised on a small α‐nucleophile library, allowed us to identify some preliminary “hits”, among which pyridinealdoximes, α‐oxo oximes, hydroxamic acids and, less active but more original, amidoximes were the most promising. Their selective phosphonothioase activity has been further confirmed by using PhX as the substrate, and thus they offer new perspectives for the synthesis of more potent V nerve agent scavengers. 相似文献