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121.
Fruit juices each have very distinct organic acids profiles that can be used as fingerprints for establishing authenticity. A method has been developed, optimised and validated for measuring by capillary electrophoresis citric, isocitric, malic and tartaric acids as authenticity markers in orange juices, without any sample treatment other than dilution and filtration. Final conditions were phosphate buffer 200 mM, pH 7.50, -14 kV as applied potential, and 57 cm length neutral capillary. Detection was direct UV at 200 nm. Different kinds and marks of orange juice, chosen from the great variety existent in the market, were analysed and clear differences could be found between them and just pressed orange juice. 相似文献
122.
Based on combined DFT/broken symmetry approach, a theoretical analysis of the exchange interactions in the VO(HPO(4)).0.5H(2)O solid is performed. Depending on the crystallographic structures reported in the literature, two very different spin models are formulated. In addition, a complete fit of the temperature-dependent (31)P NMR chemical shift is performed to determine exchange and hyperfine constants. The magnetic models used in the fit are those obtained by our theoretical calculations. The comparison between the calculated and fitted exchange constants confirms the adequacy of an isolated dimer model and rules out the alternating antiferromagnetic chain model for VO(HPO(4)).0.5H(2)O. 相似文献
123.
Luis Gerardo Pedraza Saavedra 《Journal of Russian Laser Research》2011,32(5):476-485
We complete and justify the Bohr and Rosenfeld’s extension of their seminal work on the measurability of the free electromagnetic-field
components to their pioneering paper on the measurement of charge–current uncertainty relations and the quantum control of
vacuum fluctuations. We also show that it is possible to complete the aforementioned article with pseudo-realistic graphics
of the thought experiments they designed. 相似文献
124.
125.
Pchelintsev Evgeny Pergamenshchikov Serguei Leshchinskaya Maria 《Statistical Inference for Stochastic Processes》2022,25(3):537-576
Statistical Inference for Stochastic Processes - In this paper we study a high dimension (Big Data) regression model in continuous time observed in the discrete time moments with dependent noises... 相似文献
126.
127.
Andrei D Salmon DJ Donzelli S Wahab A Klose JR Citro ML Saavedra JE Wink DA Miranda KM Keefer LK 《Journal of the American Chemical Society》2010,132(46):16526-16532
Here we describe a novel caged form of the highly reactive bioeffector molecule, nitroxyl (HNO). Reacting the labile nitric oxide (NO)- and HNO-generating salt of structure iPrHN-N(O)═NO(-)Na(+) (1, IPA/NO) with BrCH(2)OAc produced a stable derivative of structure iPrHN-N(O)═NO-CH(2)OAc (2, AcOM-IPA/NO), which hydrolyzed an order of magnitude more slowly than 1 at pH 7.4 and 37 °C. Hydrolysis of 2 to generate HNO proceeded by at least two mechanisms. In the presence of esterase, straightforward dissociation to acetate, formaldehyde, and 1 was the dominant path. In the absence of enzyme, free 1 was not observed as an intermediate and the ratio of NO to HNO among the products approached zero. To account for this surprising result, we propose a mechanism in which base-induced removal of the N-H proton of 2 leads to acetyl group migration from oxygen to the neighboring nitrogen, followed by cleavage of the resulting rearrangement product to isopropanediazoate ion and the known HNO precursor, CH(3)-C(O)-NO. The trappable yield of HNO from 2 was significantly enhanced over 1 at physiological pH, in part because the slower rate of hydrolysis for 2 generated a correspondingly lower steady-state concentration of HNO, thus, minimizing self-consumption and enhancing trapping by biological targets such as metmyoglobin and glutathione. Consistent with the chemical trapping efficiency data, micromolar concentrations of prodrug 2 displayed significantly more potent sarcomere shortening effects relative to 1 on ventricular myocytes isolated from wild-type mouse hearts, suggesting that 2 may be a promising lead compound for the development of heart failure therapies. 相似文献
128.
Alexander V. Kabanov Prof. Dr. Serguei V. Vinogradov Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(30):5418-5429
Nanogels are swollen nanosized networks composed of hydrophilic or amphiphilic polymer chains. They are developed as carriers for the transport of drugs, and can be designed to spontaneously incorporate biologically active molecules through formation of salt bonds, hydrogen bonds, or hydrophobic interactions. Polyelectrolyte nanogels can readily incorporate oppositely charged low‐molecular‐mass drugs and biomacromolecules such as oligo‐ and polynucleotides (siRNA, DNA) as well as proteins. The guest molecules interact electrostatically with the ionic polymer chains of the gel and become bound within the finite nanogel. Multiple chemical functionalities can be employed in the nanogels to introduce imaging labels and to allow targeted drug delivery. The latter can be achieved, for example, with degradable or cleavable cross‐links. Recent studies suggest that nanogels have a very promising future in biomedical applications. 相似文献
129.
Serguei Naboko Irina Pchelintseva Luis O. Silva 《Journal of Approximation Theory》2009,161(1):314-336
For a two-parameter family of Jacobi matrices exhibiting first-order spectral phase transitions, we prove discreteness of the spectrum in the positive real axis when the parameters are in one of the transition boundaries. To this end, we develop a method for obtaining uniform asymptotics, with respect to the spectral parameter, of the generalized eigenvectors. Our technique can be applied to a wide range of Jacobi matrices. 相似文献
130.
Bounds on the exponential decay of generalized eigenfunctionsof bounded and unbounded selfadjoint Jacobi matrices in are established. Two cases are considered separatelyand lead to different results: (i) the case in which the spectralparameter lies in a general gap of the spectrum of the Jacobimatrix and (ii) the case of a lower semibounded Jacobi matrixwith values of the spectral parameter below the spectrum. Itis demonstrated by examples that both results are sharp. Weapply these results to obtain a "many barriers-type" criterionfor the existence of square-summable generalized eigenfunctionsof an unbounded Jacobi matrix at almost every value of the spectralparameter in suitable open sets. In particular, this leads toexamples of unbounded Jacobi matrices with a spectral mobilityedge, i.e., a transition from purely absolutely continuous spectrumto dense pure point spectrum. 相似文献