Interpretation of ghost lines in secondary-electron spectra determined by XPS

The photoelectron energy corresponding to the Fermi level of an investigated specimen and the onset energy for detection of secondary electrons are two characteristic energy values that can be used for work-function evaluation. Secondary-electron onset measurements are usually carried out by applying an acceleration voltage between the specimen and the spectrometer entrance, giving a structured secondary-electron spectrum showing three types of secondary electrons: those from the specimen, those from the entrance-slit system, and those from the X-ray tube window. For the latter electrons the electrical field built up in the sample chamber acts as an energy analyzer, imaging a discrete energy interval onto the spectrometer entrance slit. The variation of energy and intensity of these “ghost-lines” is discussed as a function of the applied acceleration voltage and the specimen tilting angle, leading to optimized experimental parameters for recording of secondary-electron spectra.     

μLC coupled to ICP–SFMS with post-column isotope dilution analysis of sulfur for absolute protein quantification

Absolute protein quantification has become an important challenge in modern bioanalytical chemistry. Among several approaches based on mass spectrometric techniques, inductively coupled plasma (ICP) as ionisation source provides element-selective and sensitive detection of heteroatoms, and thus, a potentially emerging tool in protein analysis. In this work we applied coupling of capillary liquid chromatography (μLC) and inductively coupled plasma-sector field mass spectrometry (ICP–SFMS) to the separation and determination of standard proteins. For quantification purposes, post-column isotope dilution of sulfur was applied and optimised for this type of hyphenated technique. Provided that the protein sequence is known (number of sulfur-containing amino acids, i.e. cysteines and methionines) the protein amount can then be directly calculated from the determined sulfur content in a certain protein fraction. In order to prove the reliability of the presented method, two different certified reference materials were analysed: CRM 393 (human apolipoprotein A-I) and CRM 486 (α-fetoprotein). For CRM 393 excellent agreement (37.0 ± 1.4 μmol L⁻¹) was obtained with the certificate (37.7 ± 1.8 μmol L⁻¹). However, the recovery rate for α-fetoprotein in CRM 486 was found to be about 60% indicating incomplete elution of the protein during the chromatographic separation.     

Der Wittelsbacher und der Hope‐Diamant

Diamonds are formed from carbon at high pressures and high temperatures in the inner part of the earth. Doping with very small amounts of boron leads to diamonds with blue colour. Two of the most famous historical blue diamonds, the Wittelsbach and Hope Diamond, were found in the Indian Kollur mine. The latter was brought to Europe by the French gem merchant Tavernier. Today it is displayed in the Smithsonian Institute. The Wittelsbach Diamond was for a long time in the possession of the House Wittelsbach until it was secretly sold in Antwerp in 1951. In 2008, it was purchased by auction by the jeweller Graff who recut the gem. In 2011, it was sold to an unknown buyer. As the Wittelsbach and the Hope diamond share origin and colour, it was assumed for a long time that both are pieces from a larger crystal. By optical investigation it was now shown that they have indeed some similar optical properties, but differ strikingly in other ones. Hence, they cannot originate from the same crystal.     

Objective Bayesian Model Selection in Generalized Additive Models With Penalized Splines

We propose an objective Bayesian approach to the selection of covariates and their penalized splines transformations in generalized additive models. The methodology is based on a combination of continuous mixtures of g-priors for model parameters and a multiplicity-correction prior for the models themselves. We introduce our approach in the normal model and extend it to nonnormal exponential families. A simulation study and an application with binary outcome is provided. An efficient implementation is available in the R package hypergsplines. Supplementary materials for this article are available online.     

The division problem for tempered distributions of one variable

We give a characterization, in one variable case, of those $C^{\infty }$ multipliers F such that the division problem is solvable in $S^{\prime }(\mathbb{R})$. For these functions $F\in O_M(\mathbb{R})$ we even prove that the multiplication operator $M_F(G)=FG$ has a continuous linear right inverse on $S^{\prime }(\mathbb{R})$, in contrast to what happens in the several variables case, as was shown by Langenbruch.     

Stoffwechselprodukte von Mikroorganismen. 250. Mitteilung. Maduraferrin,ein neuartiger Siderophor aus Actinomadura madurae

Maduraferrin, a Novel Siderophore from Actinomadura madurae From a strain of Actinomadura madurae, a new siderophore was isolated. Maduraferrin is the Fe complex of an oligopeptide composed of salicylic acid, β-alanine, glycine, L -serine, N^δ-hydroxy-N^α-methyl-L -ornithine, and L -hexahydropyridazine-3-carboxylic acid. The complexing centers are a salicylamide moiety, a hydroxamic-acid group and an acid hydrazide group.