Asymptotic behavior of iterative M-estimartors for location

In this paper, we study the Huber M-estimator for location when they are computed by a class of numerical iterative procedures. This class includes the usual method of Newton-Raphson, iterated weighted least squares and iterated winsorization. We show that under mild conditions, the numerical iterative procedures converge and the resulting estimators are consistent and asymptotically normal.     

Berechnung des Gehaltes an Einzelkomponenten und deren Vertrauensintervalle im Falle der indirekten Analyse

Ohne Zusammenfassung

---

Calculation of the content of individual components and their confidence intervals in indirect analysis

---

Diese Arbeit kann im Zusammenhang mit unseren vorangehenden Beiträgen [1–3] über das Vertrauensintervall von Analysenergebnissen gesehen werden     

Die IR-Spektren von Kobalt-, Nickel- und Zink-Orthovanadat

Infrared spectra of crystalline Co₃(VO₄)₂, Ni₃(VO₄)₂ and Zn₃(VO₄)₂ as well as the laser-Raman spectrum of the last mentioned compound are reported and discussed. A series of solid solutions of the type (Zn/Ni)₃(VO₄)₂ have also been prepared and investigated, in order to obtain a wider insight into the spectroscopic behaviour of this class of compounds in the 500-250 cm^–1 region. Comparisons with the formerly investigated isotypic Mg₃(VO₄)₂ allows to confirm some of the earlier statements and assignments in the light of additional experimental information.

---

---

26. Mitt. der Reihe Orthovanadate und verwandte Verbindungen. 25. Mitt.:E. J. Baran, J. Mol. Struct., im Durck; 24. Mitt.:E. J. Baran undI. L. Botto; J. inorg. nucl. Chem., im Druck; 23. Mitt:M. E. Escobar undE. J. Baran, Z. anorg. allg. Chem., in Druck.     

Symmetry adapted functions belonging to the dirac groups

An earlier analysis of the canonical form of a pair of invertible operators obeying the exchange rule is extended to cover a set of operators, between each pair of which a relation of this type exists; and for which a power of each operator is the unit matrix. Such relations define a system which may be regarded as a generalization of the Dirac matrices of relativistic quantum mechanics. We concentrate upon the group theoretic aspects of such a system and its matrix representations. Applications arise from the fact that all projective representations of finite abelian groups take the form of a Dirac Group. In particular, the representations of the magnetic space groups, which are projective representations of the lattice groups, arise in this manner.     

Trace elements in nail polish as a source of contamination of nail clippings when used in epidemiological studies

Summary Trace elements were determined in 27 brands of nail polish using INAA so as to estimate the impact of nail polish remainders when using (finger, toe) nail clippings as a bioindicator for epidemiological studies. Fe was found to be present up to almost 1.7% in one brand. No unambiguous correlation between trace elements and color was established, though transparent polish has the lowest trace element concentrations. An estimate of the maximum effect (no removal of the paint) indicates that over-estimates of some trace element levels in nail with more than 200.000% may occur. This study showed that if nail clippings will be used to study trace elements, very high demands have to be set to the efficiency and selectivity of the cleaning procedure.     

Adsorption of silanes bearing nitrogenated Lewis bases on SiO2/Si (100) model surfaces

The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N-propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with "on-spot" MALDI-TOF MS detection.     

Synthesis of gold nanoparticles within a supramolecular gel-phase network

Gold nanoparticles with diameters of ca. 13 nm were synthesised by UV irradiation of a supramolecular organogel into which HAuCl4 and tetraoctylammonium bromide had been diffused-the gel network plays an essential role in nanoparticle stabilisation.