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61.
62.
63.
Kutscher DJ Fricker MB Hattendorf B Bettmer J Günther D 《Analytical and bioanalytical chemistry》2011,401(9):2691-2698
A method was developed for the precise and accurate determination of ovalbumin labelled with p-hydroxy-mercuribenzoic acid (pHMB) using polyacrylamide gel electrophoresis with ns-laser ablation–inductively coupled plasma
mass spectrometry. Following systematic optimisation of the ablation process in terms of detection sensitivity, two different
quantification strategies were applied: external calibration using standards of the derivatized protein after 13C+ normalization and, as a proof of concept, label-specific isotope dilution analysis (IDA) using pHMB enriched in the isotope
199Hg. Due to the inhomogeneous distribution of the protein within the gel bands, it could be demonstrated that the IDA approach
was superior in terms of precision and accuracy. Furthermore, it permits a reliable quantification, if more complex separation
protocols are applied, as typically occurring analyte loss and degradation can be compensated for as soon as complete mixture
of spike and sample is achieved. The estimated limit of detection was 160 fmol in the case of ovalbumin. In contrast to earlier
studies using metals naturally present in proteins, no loss of mercury was observed during separation under denaturing conditions
and other sample preparation steps. Using label-specific IDA, the measured isotope ratios in the gel corresponded to recoveries
between 95% and 103%. 相似文献
64.
Eng MP Shoaee S Molina-Ontoria A Gouloumis A Martín N Durrant JR 《Physical chemistry chemical physics : PCCP》2011,13(9):3721-3729
A fullerene based Donor-Bridge-Acceptor (DBA) compound, incorporating a π-extended tetrathiafulvalene electron donor, is investigated with respect to its photophysics in solution versus solid state. Solid films of neat DBA are compared with blend films where the DBA compound is diluted in the inert, low dielectric, polymer poly(styrene). It is found that the moderate intermolecular electronic coupling and donor-acceptor separation (22 ?) in this case leads to the generation of more dissociated, intermolecular charges than a mixture of the donor and acceptor reference compounds. However, the increased intermolecular interactions in the solid state lead to the excited state of the fullerene suffering from concentration self-quenching. This is found to severely affect the charge generation yield in solid films. The impact of competing intra and intermolecular interactions in the solid state upon the film photophysics is analysed in terms of a kinetic model which includes both the effects of concentration self-quenching and the impact of film composition upon the dielectric stabilisation of charge separated states. We conclude that both concentration self-quenching and dielectric stabilisation are critical in determining the photophysics of the blend films, and discuss strategies based upon our observations to enhance the charge photogeneration properties of organic films and photovoltaic devices based upon DBA compounds. 相似文献
65.
66.
Mehdi Pishahang Egil Bakken Svein Stølen Christopher Ian Thomas Paul Inge Dahl 《Ionics》2013,19(6):869-878
The oxygen non-stoichiometry and redox thermodynamic properties of the LaFe1 ? x Co x O3 ? δ system (x?=?0.25 and 0.75) are studied. At low temperatures, the LaCoO3 and LaFeO3 systems show partial solid solubility. At 1,273 K (in air), both compounds are single phases and are orthorhombic and rhombohedral for x?=?0.25 and 0.75, respectively. Thermogravimetry has been used to measure the oxygen non-stoichiometry versus oxygen partial pressure at three temperatures, 1,223, 1,273, and 1,323 K. Redox thermodynamic quantities are extracted directly from the oxygen non-stoichiometry curves. The extracted enthalpies of oxidation do not vary significantly with stoichiometry, and for x?=?0.25 and 0.75, they are ?640?±?60 and ?440?±?60 kJ (mol O2)?1, respectively. Ideal solid solution thermodynamic models are used to analyze the redox mechanisms. 相似文献
67.
M. Dahl G. Janotta G. Schaack Shi Shan 《Zeitschrift für Physik B Condensed Matter》1989,76(3):327-334
The magnetic splitting of triply degenerate (T
2g
)-phonons in the cubic Rare Earth compound dysprosium-aluminum-garnet could be observed making use of the polarization properties of the Raman-effect.The theoretical predictions of a phenomenological symmetry analysis are compared to a more detailed microscopic treatment of the observations in terms of the magnetoelastic interaction. 相似文献
68.
69.
We have used the quantum-chemical concept of biorthonormal electronic basis functions to derive the two-centre electron exchange integrals in non-diabatic electron transfer reactions. It is shown that only non-diagonal parts induce the transfer corresponding to inclusion of the diagonal parts in the zero-order hamiltonians. This result coincides with the result derived previously by means of scattering theory. 相似文献
70.
Otto Dahl 《Tetrahedron letters》1981,22(34):3281-3284
Reactions of one diasteveomer of a XP-NMe2 compound () with alcohols, phenol and amines have been shown by NMR to proceed uith initial inversion at phosphorus, but the overall reactions are not stereoselective. 相似文献