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1.
Ginette Ratovo Jean‐Pierre Souchard Pascale Urizzi Yvon Coulais Franoise Nepveu Etienne Hollande 《应用有机金属化学》2004,18(1):1-8
Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, 111In–L–LDL and 153Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of 111In–L–LDL and 153Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (111In citrate and 153Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as 111In or 153Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that 111In–L–LDL and 153Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with 153Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
2.
Jocelyn Jalbert Roland Gilbert Pierre Tétreault Brigitte Morin Denise Lessard-Déziel 《Cellulose (London, England)》2007,14(4):295-309
In this study, headspace gas chromatography/mass spectrometry has been used to assess the volatile by-products generated by
the ageing of oil-impregnated paper insulation of power transformers. Sealed-glass ampoules were used to age under oxidative
conditions 0.5-g specimens of insulating paper in 9 mL of inhibited mineral oil in a temperature range of 60–120 °C and moisture
of 0.5, 1 and 2% (w/w). A linear relationship between one of the oil-soluble degradation by-products, i.e. methanol, and the
number of ruptured 1,4-β-glycosidic bonds of cellulose, regardless of the type of paper (ordinary Kraft or thermally-upgraded
(TU) Kraft paper), was established for the first time in this field. Ageing at 130 °C of model compounds of the Kraft paper
constituents (α-cellulose, hemicellulose and lignin) and two cellulosic breakdown by-products (D-(+)-glucose and 1,6-anhydro-β-d-glucopyranose) confirmed that the α-cellulose degradation was mostly responsible for the presence of this molecule in the
system. Furthermore, additional 130 °C-tests with six different papers and pressboard samples under a tight control of initial
moisture indicated that at least one molecule of methanol is formed for each rupture of 1,4-β-glucosidic bond of the molecular
chains. Stability tests showed that the ageing indicator is stable under the oxygen and temperature conditions of open-breathing
transformers. The presence of methanol was detected in 94% of oil samples collected from over than 900 in-service pieces of
equipment, confirming the potential for this application. Lastly, the tests have shown that oil-oxidation by-products and
TU-nitrogenous agents modify the methanol partitioning coefficients in the paper/oil/air system, which makes their study essential
over a range of field conditions encountered by power transformers. Results are presented and discussed in comparison with
2-furfuraldehyde, which is the current reference in the domain. 相似文献
3.
The previously reported (J. Mol. Spectrosc.68, 195–222 (1977)) study of the CH3D spectrum occurring at 1033–1270 cm?1 which was mainly concerned with the ν6 fundamental has now been extended to cover the region 1270–1420 cm?1. In all, 342 transitions belonging to the ν3 band are now assigned. Both the ν3 and ν6 bands are processed simultaneously taking into account of the Coriolis interaction between them, and the fitting of all the experimental data led to 21 significant spectroscopic constants for the states v6= 1 and v3 = 1 of CH3D. 相似文献
4.
5.
J. Hubert S. Bordeleau K. C. Tran S. Michaud B. Milette R. Sing J. Jalbert D. Boudreau M. Moisan J. Margot 《Fresenius' Journal of Analytical Chemistry》1996,355(5-6):494-500
The use of microwave induced plasmas, particularly of surface wave plasmas, as detectors in atomic emission spectrometry for elemental analysis is reviewed. Surface wave plasmas have been produced at low HF power and used as gas chromatographic detectors. The analytical performances for the detection of non-metals with a Fourier transform spectrometer and a two-channel filter unit are reported. The excitation behavior of non-metals in helium-based mixed gas-plasmas has also be studied. In particular, the effect of power and of nitrogen concentration on the bromine emission has been systematically investigated. A nine-fold improvement of the detection limits for bromine can be obtained in a high power (900 W) helium-nitrogen (0.1–0.2%) plasma. 相似文献
6.
Ginette Gauyacq 《Discrete Applied Mathematics》1997,80(2-3):149-160
We present a technique for building, in some Cayley graphs, a routing for which the load of every edge is almost the same. This technique enables us to find the edge-forwarding index of star graphs and complete-transposition graphs. 相似文献
7.
8.
Rapid postcolumn methodology for determination of paralytic shellfish toxins in shellfish tissue 总被引:1,自引:0,他引:1
Rourke WA Murphy CJ Pitcher G van de Riet JM Burns BG Thomas KM Quilliam MA 《Journal of AOAC International》2008,91(3):589-597
A rapid liquid chromatographic (LC) method with postcolumn oxidation and fluorescence detection (excitation 330 nm, emission 390 nm) for the determination of paralytic shellfish toxins (PSTs) in shellfish tissue has been developed. Extracts prepared for mouse bioassay (MBA) were treated with trichloroacetic acid to precipitate protein, centrifuged, and pH-adjusted for LC analysis. Saxitoxin (STX), neoSTX (NEO), decarbamoylSTX (dcSTX), and the gonyautoxins, GTX1, GTX2, GTX3, GTX4, GTX5, dcGTX2, and dcGTX3, were separated on a polar-linked alkyl reversed-phase column using a step gradient elution; the N-sulfocarbamoyl GTXs, C1, C2, C3, and C4, were determined on a C-8 reversed-phase column in the isocratic mode. Relative toxicities were used to determine STX-dihydrochloride salt (diHCl) equivalents (STXeq). Calibration graphs were linear for all toxins studied with STX showing a correlation coefficient of 0.999 and linearity between 0.18 and 5.9 ng STX-diHCI injected (equivalent to 3.9-128 microg STXeq/100 g in tissue). Detection limits for individual toxins ranged from 0.07 microg STXeq/100 g for C1 and C3 to 4.1 microg STXeq/100 g for GTX1. Spike recoveries ranged from 76 to 112% in mussel tissue. The relative standard deviation (RSD) of repeated injections of GTX and STX working standard solutions was < 4%. Uncertainty of measurement at a level of 195 microg STXeq/100 g was 9%, and within-laboratory reproducibility expressed as RSD was 4.6% using the same material. Repeatability of a 65 microg STXeq/100 g sample was 3.0% RSD. Seventy-three samples were analyzed by the new postcolumn method and both AOAC Official Methods for PST determination: the MBA (y = 1.22x + 13.99, r2 = 0.86) and the precolumn LC oxidation method of Lawrence (y = 2.06x + 12.21, r2 = 0.82). 相似文献
9.
Roland Gilbert Jocelyn Jalbert Pierre Tétreault Brigitte Morin Yves Denos 《Cellulose (London, England)》2009,16(2):327-338
Recently, the existence of a relation between the rupture of 1,4-β-glycosidic bonds in the cellulose during thermal-ageing of paper/oil systems and the detection of methanol in the oil has been reported for the first time in this journal (Jalbert et al. 2007). The present study addresses the rate constants of the reaction for standard wood kraft papers, two immersed in inhibited naphthenic oil under air (paper/oil weight–volume ratio of 1:18) and one in non-inhibited paraffinic oil under nitrogen (paper/oil weight–volume ratio of 1:30). The isotherms in the range of 60–130 °C show that the initial rate of methanol production markedly increases with temperature and to a lesser extent with the moisture of the specimens (initially between 0.5 and 2.25% (w/w)), similarly to what is noted for the depolymerization through the Ekenstam’s pseudo-zero order model. The Arrhenius expression of the rate constants reveals linear relationships that confirm the dominance of a given mechanism in both cases. A very good agreement is also noted for the activation energy over the entirely paper/oil systems studied (106.9 ± 4.3 and 103.5 ± 3.7 kJ mol?1 for methanol and scissions, respectively). Furthermore, a comparison of the rate constants $ \left( {k_{{{\text{CH}}_{ 3} {\text{OH}}}} /k_{\text{scissions}} } \right) Recently, the existence of a relation between the rupture of 1,4-β-glycosidic bonds in the cellulose during thermal-ageing of paper/oil systems and the detection of methanol in the oil has
been reported for the first time in this journal (Jalbert et al. 2007). The present study addresses the rate constants of the reaction for standard wood kraft papers, two immersed in inhibited
naphthenic oil under air (paper/oil weight–volume ratio of 1:18) and one in non-inhibited paraffinic oil under nitrogen (paper/oil
weight–volume ratio of 1:30). The isotherms in the range of 60–130 °C show that the initial rate of methanol production markedly
increases with temperature and to a lesser extent with the moisture of the specimens (initially between 0.5 and 2.25% (w/w)),
similarly to what is noted for the depolymerization through the Ekenstam’s pseudo-zero order model. The Arrhenius expression
of the rate constants reveals linear relationships that confirm the dominance of a given mechanism in both cases. A very good
agreement is also noted for the activation energy over the entirely paper/oil systems studied (106.9 ± 4.3 and 103.5 ± 3.7 kJ mol−1 for methanol and scissions, respectively). Furthermore, a comparison of the rate constants shows approximately constant values indicating an apparent yield for the methanol of about one-third molecule per every scission
for the tests under air (0.27 ± 0.04 for Clupak HD75 and 0.37 ± 0.14 for Munksj? TH70) and even lower for the ones under N2 (0.12 ± 0.03 for Munksj? E.G.). As expected from a pseudo-zero order model, these values were shown to be consistent with
a similar comparison of the amount of CH3OH and chain-end groups produced under specific time–temperature ageing conditions (168 h at 120 °C). Finally, an additional
test carried out with unaged cellulose in contact with a fresh solution of methanol in oil (cellulose/oil weight–volume ratio
of 1:18) shows that at equilibrium, over 58% of the species is lost from the solution due to penetration into the fibres.
Such results reveal the importance of the species partitioning in establishing the true correspondence between the molecules
of CH3OH produced and the scissions. 相似文献
10.
We report on the accelerated ageing of cellulose based insulating paper by means of pulsed UV laser irradiation (λ = 248 nm)
under various experimental conditions including paper composition, background gas (He, N2 and air) and moisture content of the paper. The temperature reached by the paper samples during their laser irradiation was
monitored by means of real-time IR imaging. It is shown that the equilibrium temperature (T
eq) reached by the paper increases from ~30 to ~270 °C when the laser energy density was raised from 15 to 550 mJ cm−2. The laser irradiated samples were systematically characterized by means of scanning electron microscopy (SEM) observations
and degree of polymerization (DPv) measurements. Interestingly, it is found that, for a given moisture content, the degradation level of the cellulose is mainly
triggered by the T
eq value reached during the laser irradiation. Moreover, their moisture content was found to influence significantly the number
of laser produced bond scissions (it doubles when the moisture content is increased from 0.5 to 6%); the paper degradation
is apparently not affected by the presence of oxygen as the background gas. These results suggest that the laser induced cellulose
degradation occurs through a direct photolysis (i.e. direct breakage of C–C, C–O and C–H bonds), leading to radicals formation,
which, in turn, are believed to induce the acid hydrolysis degradation mechanism, the latter being moisture dependent. The
activation energy (E
a) of each gaseous species collected after the laser degradation was estimated. Their E
a values were found to be in good agreement with the one associated to the laser depolymerisation of cellulose (i.e. ~56 kJ mol−1), suggesting thereby a direct correlation between the cellulose degradation and the formation of the detected gaseous species.
Finally, the pulsed laser irradiation can be seen as an attractive tool to identify primarily generated molecules, on a very
short time scale, that can be used as relevant chemical markers for the monitoring of the ageing of transformers materials
with cellulose. 相似文献