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101.
Zhang MY Pace N Kerns EH Kleintop T Kagan N Sakuma T 《Journal of mass spectrometry : JMS》2005,40(8):1017-1029
The use of a hybrid triple quadrupole-linear ion trap (QqQ(LIT)) mass spectrometer system for a comprehensive study of fragmentation mechanisms is described. The anxiolytic drug, buspirone, was chosen as a model compound for this study. With the advent of a QqQ(LIT) instrument, both the traditional quadrupole and the new linear ion trap scans (LIT) could be performed in a single LC run. In the past, a sample had to be run on two different instruments, namely, a triple quadrupole instrument (QqQ) and a 3D ion trap (3D IT) to obtain similar information. With the new QqQ(LIT) technology, collision-induced dissociation (CID) occur in a quadrupole collision cell, q2, and fragment ions are trapped and analyzed in Q3 operated in LIT mode. In this work, high-sensitivity product ion spectra of buspirone were obtained from the one-stage 'Enhanced Product Ion' scan (EPI) with rich product ions and no low mass cut-off. Furthermore, detailed fragmentation pathways were elucidated by further dissociation of each of the fragment ions in the EPI spectrum using MS(3) mode in the same run. The MS(3) scan was performed by incorporating CID in q2, and trapping, cooling, isolation, and resonance-excitation in Q3 when operating in LIT mode. This approach allowed unambiguous assignment of all fragment ions quickly with fewer experiments and easier interpretation than the previous approach. The overall sensitivity for obtaining complete fragment ion data was significantly improved for QqQ(LIT) as compared with that of QqQ and 3D IT mass spectrometers. This is beneficial for structure determination of unknown trace components. The method allowed structure determination of metabolites of buspirone in rat microsomes at 1 microM concentration, which was a 10-fold lower concentration than was needed for QqQ or 3D IT instruments. The QqQ(LIT) instrument provided a simple, rapid, sensitive and powerful approach for structure elucidation of trace components. 相似文献
102.
Radial basis function (RBF) interpolation can be very effective for scattered data in any number of dimensions. As one of their many applications, RBFs can provide highly accurate collocation-type numerical solutions to several classes of PDEs. To better understand the accuracy that can be obtained, we survey here derivative approximations based on RBFs using a similar Fourier analysis approach that has become the standard way for assessing the accuracy of finite difference schemes. We find that the accuracy is directly linked to the decay rate, at large arguments, of the (generalized) Fourier transform of the radial function. Three different types of convergence rates can be distinguished as the node density increases – polynomial, spectral, and superspectral, as exemplified, for example, by thin plate splines, multiquadrics, and Gaussians respectively.
Bengt Fornberg: The work was supported by NSF grants DMS-9810751 (VIGRE), DMS-0073048 and DMS-0309803.Natasha Flyer: The work was supported by the NSF grant DMS-9810751 (VIGRE). 相似文献
103.
Boundedness of maximal operators and potential operators on Carleson curves in Lebesgue spaces with variable exponent 总被引:1,自引:0,他引:1
We prove the boundedness of the maximal operator Mr in the spaces L^p(·)(Г,p) with variable exponent p(t) and power weight p on an arbitrary Carleson curve under the assumption that p(t) satisfies the log-condition on Г. We prove also weighted Sobolev type L^p(·)(Г, p) → L^q(·)(Г, p)-theorem for potential operators on Carleson curves. 相似文献
104.
Natasha?RozhkovskayaEmail authorView authors OrcID profile 《Algebras and Representation Theory》2018,21(5):1165-1176
We deduce from a determinant identity on quantum transfer matrices of generalized quantum integrable spin chain model their generating functions. We construct the isomorphism of Clifford algebra modules of sequences of transfer matrices and the boson space of symmetric functions. As an application, tau-functions of transfer matrices immediately arise from classical tau-functions of symmetric functions. 相似文献
105.
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107.
[structure: see text] The synthesis of unsaturated beta-linked C-disaccharides by the Lewis acid-mediated reaction of 3-O-acetylated glycals with monosaccharide-derived alkenes is described. Deprotection and selective hydrogenation of an exocyclic carbon-carbon double, in the presence of an endocyclic double bond, for representative targets is also illustrated. 相似文献
108.
For a convolution operator of the form \(K = \sum\nolimits_{j = 0}^{N - 1} {P_j A_j } \) discrete Wiener—Hopf operators and Pj are coordinate projections whose indices are congruent to j modulo N, necessary and sufficient conditions for it to be Nötherian inl p+(i ?p ? ∞),c + 0 and formulas for the index are obtained. 相似文献
109.
Lars-Erik Persson Natasha Samko Peter Wall 《Journal of Fourier Analysis and Applications》2016,22(2):413-426
We find conditions for the weighted boundedness of a general class of multidimensional singular integral operators in generalized Morrey spaces \(\mathcal {L}^{p,\varphi }(\mathbb {R}^n,w),\) defined by a function \(\varphi (x,r)\) and radial type weight \(w(|x-x_0|), x_0\in {\mathbb {R}}^{n}.\) These conditions are given in terms of inclusion into \(\mathcal {L}^{p,\varphi }(\mathbb {R}^n,w),\) of a certain integral constructions defined by \(\varphi \) and w. In the case of \(\varphi =\varphi (r)\) we also provide easy to check sufficient conditions for that in terms of indices of \(\varphi \) and w. 相似文献
110.