Relatively Bounded Rank One Perturbations of Non-Analytic Semigroups Can Generate Large Point Spectrum

It is known that relatively bounded compact perturbations of analytic semigroups yield again generators of analytic semigroups. On the other hand, for each non-analytic semigroup there is a relatively bounded rank one perturbation which is no longer a generator. In this note we show that in fact any non-analytic semigroup admits a relatively bounded rank one perturbation with a sequence of eigenvalues z_j such that the real parts R(z_j) converge to infinity.     

The photoelectric aerosol sensor as a fast-responding and sensitive detection system for cigarette smoke analysis

Summary The combination of the photoelectric aerosol sensor (PAS) and the time programmed sampling of small aerosol volumes within a cigarette puff allows the quantitative time-resolved determination of photoemitting substances in the aerosol. All photoemitting substances contribute to the measured photoelectric (PE) signal. In this comparative study it is shown that the PAS signal correlates well (r=0.94, n=20) with the BaP content. The benzo-a-pyrene (BaP) amounts of the cigarette smoke aerosol were separately determined by in situ synchronous fluorimetry on TLC plates. The absolute detection limit is about 50 pg.

---

Photoelektrischer Aerosolsensor als schnell ansprechendes und empfindliches Detektionssystem zur Analyse von Zigarettenrauch

     

Analytical Study of Extracts of St John’s Wort (Hypericum perforatum), Evaluation of HPTLC Plates by Multivariate Data Analysis

JPC – Journal of Planar Chromatography – Modern TLC - HPTLC with multivariate data analysis has been used as a new means of evaluating the quality of herbal extracts. Spectral data from...     

Thin-layer chromatography and multivariate data analysis of willow bark extracts

In most cases the pharmacological activity of plant extracts is not assigned to single components and often not all active ingredients are known. Approaches other than those considering single compounds only to analyze plant material have proven helpful for a better characterization of extracts in their entirety. In this study extracts of willow bark are analyzed by high-performance thin-layer chromatography (HPTLC) and two different pharmacological tests [the 2,2'-azobis (2-amidinopropane) dihydrochloride reaction and the xanthine/xanthine oxidase reaction] with the help of multivariate data analysis. Described are two models using the results of the chromatographic study of 22 various extracts of willow bark and their pharmacological properties. The chromatographic data are obtained by a special TLC scanner that enables measurement of HPTLC tracks simultaneously in the range of lambda = 200-400 nm. Additionally, the developed models are used to predict the activity of another three extracts of willow bark demonstrating the quality of the model.     

Surface activation influencing the microstructure of Zn(Ca) phosphate coatings

Zinc and zinc calcium phosphate coatings on steel were formed by dipping in commercial baths. A surface activation with titanium phosphate influences not only the film morphology but also the composition of the conversion films. Qualitative phase analysis of the polycrystalline deposits reveals a typical phosphophyllite crystal growth apart from hopeite and scholzite respectively. The growth rate depends on the free surface of the steel; the contact area to the solution controls the rate of iron pickling.     

Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs1.7Se0.2

Single crystals of HfAs_1.7Se_0.2 are grown by chemical transport reaction and their chemical composition characterized in detail by various analytical methods. Chemical analyses and crystal structure investigations by single‐crystal X‐ray diffraction as well as powder diffraction with synchrotron radiation reveal a tetragonal PbFCl structure type with strong disorder caused by a significant arsenic deficiency (As_0.9) on the 2a site and mixed occupancy of the 2c site (As_0.8Se_0.2). HfAs_1.7Se_0.2 is a diamagnetic metal which transforms into a superconducting state at T_c=0.52 K. Similar to other PbFCl‐type arsenide selenides, the title compound displays a magnetic‐field‐independent ?AT^1/2 term in the low‐temperature electrical resistivity. This unusual term presumably originates from the electron scattering of structural two‐level systems. According to the experimental results, HfAs1.7Se0.2 appears to be a rare example of a nonmagnetic Kondo material.