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Dr. María Francisco M.Sc. Adriaan van den Bruinhorst Prof. Dr. Maaike C. Kroon 《Angewandte Chemie (International ed. in English)》2013,52(11):3074-3085
A new generation of designer solvents emerged in the last decade as promising green media for multiple applications, including separation processes: the low‐transition‐temperature mixtures (LTTMs). They can be prepared by mixing natural high‐melting‐point starting materials, which form a liquid by hydrogen‐bond interactions. Among them, deep‐eutectic solvents (DESs) were presented as promising alternatives to conventional ionic liquids (ILs). Some limitations of ILs are overcome by LTTMs, which are cheap and easy to prepare from natural and readily available starting materials, biodegradable, and renewable. 相似文献
94.
E. den Boer R. J. W. Meesters B. D. van Zelst T. M. Luider J. M. W. Hazes S. G. Heil R. de Jonge 《Analytical and bioanalytical chemistry》2013,405(5):1673-1681
The folate antagonist methotrexate (MTX) is the anchor drug in the treatment of rheumatoid arthritis. The therapeutic effects of MTX are attributed to the intracellular levels of MTX, present in the cell as polyglutamates (MTXPGn). We developed a new liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS)-based assay to separately quantitate MTXPGn in red blood cells using stable-isotope-labelled internal standards. Samples were analyzed by LC-ESI-MS/MS using a Waters Acquity UPLC BEH C18 column with a 5–100% organic gradient of 10 mM ammonium bicarbonate (pH 10) and methanol. The analysis consisted of simple sample preparation and a 6-min run time. Detection was done using a Waters Acquity UPLC coupled to a Waters Quattro Premier XE with electrospray ionization operating in the positive ionization mode. Assay validation was performed following recent Food and Drug Administration guidelines. The method was linear from 1–1,000 nM for all MTXPGn (R 2?>?0.99). The coefficient of variation ranged from 1–4% for intraday precision and 6–15% for interday precision. Samples were stable for at least 1 month at ?80 °C. Recovery ranged from 98–100%, and the relative matrix-effect varied from 95–99%. The lower limit of quantitation was 1 nM for each MTXPGn. Fifty patient samples from the tREACH study were analyzed. The MTXPGn concentration and distribution of these samples were comparable with values reported in literature. The developed LC-ESI-MS/MS method for the quantitative measurement of MTXPGn in red blood cells is both sensitive and precise within the clinically relevant range. The method can be easily applied in clinical laboratories due to the combination of simple pre-treatment with robust LC-ESI-MS/MS. Figure
The seperation of methotrexate polyglutamates using UPLC. 相似文献
95.
A variety of propenamidines 3 have been reacted with enamines of cyclopentanone and cyclohexanone giving after hydrolysis of the Stork enamine 6, 2-β-amidinoethylcyclopentanones 8 and -hexanones 7. This reaction illustrates the electrophilic character of the C=C double bond due to the conjugated amidine function, thus providing with propenamidines 3 a new class of Michael acceptors for enamines. 相似文献
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98.
Anne-Sophie Schou Jdal Tomasz Pawel Czaja Frans W. J. van den Berg Birthe Mller Jespersen Kim Lambertsen Larsen 《Molecules (Basel, Switzerland)》2021,26(8)
Cyclodextrins (CDs) are cyclic oligosaccharides that have found widespread application in numerous fields. CDs have revealed a number of various health benefits, making them potentially useful food supplements and nutraceuticals. In this study, the impact of α-, β-, and γ-CD at different concentrations (up to 8% of the flour weight) on the wheat dough and bread properties were investigated. The impact on dough properties was assessed by alveograph analysis, and it was found that especially β-CD affected the viscoelastic properties. This behavior correlates well with a direct interaction of the CDs with the proteins of the gluten network. The impact on bread volume and bread staling was also assessed. The bread volume was in general not significantly affected by the addition of up to 4% CD, except for 4% α-CD, which slightly increased the bread volume. Larger concentrations of CDs lead to decreasing bread volumes. Bread staling was investigated by texture analysis and low field nuclear magnetic resonance spectroscopy (LF-NMR) measurements, and no effect of the addition of CDs on the staling was observed. Up to 4% CD can, therefore, be added to wheat bread with only minor effects on the dough and bread properties. 相似文献
99.
Zimmer O Baumann K Fertl M Franke B Mironov S Plonka C Rich D Schmidt-Wellenburg P Wirth HF van den Brandt B 《Physical review letters》2007,99(10):104801
We report the first successful extraction of accumulated ultracold neutrons (UCN) from a converter of superfluid helium, in which they were produced by downscattering neutrons of a cold beam from the Munich research reactor. Windowless UCN extraction is performed in vertical direction through a mechanical cold valve. This prototype of a versatile UCN source is comprised of a novel cryostat designed to keep the source portable and to allow for rapid cooldown. We measured time constants for UCN storage and extraction into a detector at room temperature, with the converter held at various temperatures between 0.7 and 1.3 K. The UCN production rate inferred from the count rate of extracted UCN is close to the theoretical expectation. 相似文献
100.
We show, through a refinement of the work theorem, that the average dissipation, upon perturbing a Hamiltonian system arbitrarily far out of equilibrium in a transition between two canonical equilibrium states, is exactly given by =W-DeltaF=kTD(rho||rho[over ])=kT, where rho and rho[over ] are the phase-space density of the system measured at the same intermediate but otherwise arbitrary point in time, for the forward and backward process. D(rho||rho[over ]) is the relative entropy of rho versus rho[over ]. This result also implies general inequalities, which are significantly more accurate than the second law and include, as a special case, the celebrated Landauer principle on the dissipation involved in irreversible computations. 相似文献