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991.
Przemyslaw Mielczarek Piotr Suder Igor Kotsan Anna Bodzon-Kulakowska 《Journal of mass spectrometry : JMS》2023,58(4):e4916
Imaging mass spectrometry is a powerful technique for the molecular analysis of tissue sections. As in many analytical methods, sample preparation is one of the main and most important steps to obtain results of good quality. Usually, the matrix concentration and solvent composition in different studies are taken for granted without any further consideration. In our studies, we aimed to find how matrix concentration and a type of solvent influence the signal. Moreover, we also aimed to find the relationship between these parameters, how they influence the spectra, and how they influence obtained ion maps. In our experiments, we used SunCollect®, which is a commercially available wet-interface system for matrix deposition. We decided to choose two matrix concentrations (2,5-dihydroxybenzoic acid [DHB]: 15 and 25 mg/mL; 9-aminoacridine [9AA]: 7 and 5 mg/mL) and two different water solutions of solvents in two different percentages for the matrices (DHB: 50% and 70% of methanol [MeOH] and acetonitrile [ACN]; 9AA 70% and 50% of ethanol [EtOH] and MeOH). In the end, the influence of these parameters on obtained spectra and ion maps was assessed. 相似文献
992.
Monperrus M Rodriguez Gonzalez P Amouroux D Garcia Alonso JI Donard OF 《Analytical and bioanalytical chemistry》2008,390(2):655-666
A new double-spiking approach, based on a multiple-spiking numerical methodology, has been developed and applied for the accurate
quantification of inorganic mercury (IHg) and methylmercury (MeHg) by GC–ICPMS in different environmental matrices such as
water, sediments and a wide range of biological tissues. For this purpose, two enriched mercury species (201MeHg and 199IHg) were added to the samples before sample preparation in order to quantify the extents of the methylation and demethylation
processes, and thereby correct the final species concentrations. A critical evaluation of the applicability of this methodology
was performed for each type of matrix, highlighting its main advantages and limitations when correcting for the conversion
reactions of the species throughout the whole sample preparation procedure. The double-spike isotope dilution (DSIDA) methodology
was evaluated by comparing it with conventional species specific isotope dilution (IDA) when analysing both certified reference
materials and environmental samples (water, biotissues and sediment). The results demonstrate that this methodology is able
to provide both accurate and precise results for IHg and MeHg when their relative concentrations are not too different (ratio
MeHg/IHg > 0.05), a condition that holds for most natural waters and biotissues. Significant limitations on the accurate and
precise determination of the demethylation factor are however observed, especially for real sediment samples in which the
relative concentrations of the species are substantially different (ratio MeHg/IHg < 0.05). A determination of the sources
of uncertainty in the methylation/demethylation factors has demonstrated that the accurate and precise measurement of the
isotope ratios in the species involved in the transformations is crucial when quantifying the extents of these reactions.
Although the double-spike methodology is established as a reference approach that permits the correction of most analytical
biases and the accurate quantification of Hg species, some limitations have been identified for the first time in this work. 相似文献
993.
When A∈B(H) and B∈B(K) are given, we denote by MC the operator acting on the Hilbert space H⊕K of the form . In this note, it is shown that the following results in [Hai-Yan Zhang, Hong-Ke Du, Browder spectra of upper-triangular operator matrices, J. Math. Anal. Appl. 323 (2006) 700-707]
994.
E. Ghorbani G.B. Khosrovshahi Ch. Maysoori 《Journal of Combinatorial Theory, Series A》2008,115(5):878-887
Given integers t, k, and v such that 0?t?k?v, let Wtk(v) be the inclusion matrix of t-subsets vs. k-subsets of a v-set. We modify slightly the concept of standard tableau to study the notion of rank of a finite set of positive integers which was introduced by Frankl. Utilizing this, a decomposition of the poset 2[v] into symmetric skipless chains is given. Based on this decomposition, we construct an inclusion matrix, denoted by , which is row-equivalent to Wtk(v). Its Smith normal form is determined. As applications, Wilson's diagonal form of Wtk(v) is obtained as well as a new proof of the well-known theorem on the necessary and sufficient conditions for existence of integral solutions of the system Wtkx=b due to Wilson. Finally we present another inclusion matrix with similar properties to those of which is in some way equivalent to Wtk(v). 相似文献
995.
揭示几类矩阵之间的紧密联系.借助于群的子群的判定以及循环布尔矩阵是本原矩阵的判定方法,得到循环模糊矩阵成为幂等矩阵的充要条件,反循环布尔矩阵成为本原矩阵的充要条件.并给出了循环模糊矩阵成为幂等矩阵的判定方法,反循环布尔矩阵成为本原矩阵的判定方法. 相似文献
996.
A.?N.?IvanovEmail author M.?Cargnelli M.?Faber H.?Fuhrmann V.?A.?Ivanova J.?Marton N.?I.?Troitskaya J.?Zmeskal 《The European Physical Journal A - Hadrons and Nuclei》2005,23(1):79-111
We study kaonic deuterium, the bound K-d state AK d. Within a quantum field-theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K-d scattering near threshold is defined by the resonances (1405), (1750) and a smooth elastic background, and the inelastic channels K-d NY and K-d NY, where Y = ±,{0} and {0}, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays AKd NY and experimental data on the rates of the NY pair production in the reactions K-d NY. We obtain {1s} = (630±100)eV. For the shift of the energy level of the ground state of kaonic deuterium we predict {1s} = (325±60)eV. 相似文献
997.
On the Diaconis-Shahshahani Method in Random Matrix Theory 总被引:2,自引:0,他引:2
If Γ is a random variable with values in a compact matrix group K, then the traces Tr(Γj) (j ∊ N) are real or complex valued random variables. As a crucial step in their approach to random matrix eigenvalues, Diaconis
and Shahshahani computed the joint moments of any fixed number of these traces if Γ is distributed according to Haar measure
and if K is one of Un, On or Spn, where n is large enough. In the orthogonal and symplectic cases, their proof is based on work of Ram on the characters of Brauer
algebras.
The present paper contains an alternative proof of these moment formulae. It invokes classical invariant theory (specifically,
the tensor forms of the First Fundamental Theorems in the sense of Weyl) to reduce the computation of matrix integrals to
a counting problem, which can be solved by elementary means. 相似文献
998.
Rafal Latala 《Proceedings of the American Mathematical Society》2005,133(5):1273-1282
We show that for any random matrix with independent mean zero entries
where is some universal constant.
where is some universal constant.
999.
In this note we modify a recent example of Tao and give an example of a set such that admits an orthonormal basis of exponentials for some set , but which does not tile by translations. This shows that one direction of Fuglede's conjecture fails already in dimension 4. Some common properties of translational tiles and spectral sets are also proved.
1000.
A new method of calculating nonequilibrium density matrices with the aid of the quantum integrals of motion is proposed. The method is shown to be very effective in the case of systems described by means of quadratic Hamiltonians. The possibility of constructing phenomenological nonstationary Hamiltonians for a wide class of dissipative systems is discussed. The exact formulas for nonequilibrium density matrices of arbitrary quadratic systems are obtained. The quantum problem of the motion of a charged particle in uniform electric and magnetic fields in the presence of a frictional force proportional to the velocity is solved exactly by means of introducing the new phenomenological Hamiltonian. 相似文献