Factors affecting the self-excitation of low-frequency oscillations in an electric discharge

The influence of the individual factors affecting the production of low-frequency oscillations connected with moving striations in a discharge is analysed and experimentally verified. From the conception of two mechanisms of feedback, which leads to self-excitation of these oscillations, it follows that the following influence the production of oscillations: 1) the tendency of the plasma to stratification, 2) the length of the positive column, 3) processes in regions at the electrodes, 4) the external electric circuit.The measurements confirm the influence of all these factors. It is shown that the main factor conditioning the production of oscillations is the property of the plasma of the positive column — its tendency to stratification. The plasma of a glow discharge in neon — in the region of low pressures and currents investigated — has a very strong tendency to stratification with the exception of a small interval in the neighbourhood of the pressure of 4 mm Hg and current 3 . Low-frequency oscillations and moving striations are therefore very often present in a discharge in neon.The influence of the external circuit on the oscillations investigated was also experimentally proved, but it is very weak.     

Ein neuer Typ der laufenden Schichten in Neon

Ohne Zusammenfassung

---

     

Mikrophy'sikalische Vorgänge,die die Entstehung der Schnellen Schichtungswellen in der Neonglimmentladung bedingen

Zusammenfassung Im nachstehenden Artikel werden mikrophysikalische Vorgänge behandelt, die das Auftreten schneller Schichtungswellen in Neonglimmentladungen veranlassen können. Es werden sowohl die qualitativen Abhängigkeiten, als auch die ziffernmäigen Werte der Parameter der Schichtungswellen mit den charakteristischen Gröenwerten der in diesem Entladungstypus vor sich gehenden Vorgänge verglichen. Auf Grund der vorgenommenen Vergleiche kann gesagt werden, da die Relaxationszeiten der schnellen Wellen durch die Diffusionslebensdauer der atomaren, bzw. molekularen Ionen gegeben sind.

---

,

, . , . , , .

---

---

Zum Schlu danken wir F. Kroupa und V. Krejí für die aufmerksame Lesung der Arbeit und wertvolle Hinweise.     

Multicomponental Fluorimetric Determination of Aluminium, Gallium and Indium

For the fast characteristics of mixtures of Aluminium, Gallium and Indium the fluorimetric evaluation in the form of complexes with 8-Hydroxyquinoline-5-sulphonic acid is described at selected pH. The highly collinear correlated fluorescent spectra and their first derivation were evaluated under various experimental conditions with the Multiple Linear Regression (MLR), Partial Least Squares (PLS) methods and Kalman filtering. When comparing the results, the PLS gives the least relative prediction errors under optimal conditions, 5.6–15.9% for the concentration range of Al 0.025–0.2 μg cm⁻³, Ga 0.1–0.8 μg cm⁻³ and In 0.1–0.8 μg cm⁻³ in the mixture.     

A characterization of sets in ℝ2 with DC distance function

Czechoslovak Mathematical Journal - We give a complete characterization of closed sets F ? ?2 whose distance function dF:= dist(·, F) is DC (i.e., is the difference of two convex...     

Sensitive voltammetric detection of DNA damage at carbon electrodes using DNA repair enzymes and an electroactive osmium marker

This paper presents a new approach to electrochemical sensing of DNA damage, using osmium DNA markers and voltammetric detection at the pyrolytic graphite electrode. The technique is based on enzymatic digestion of DNA with a DNA repair enzyme exonuclease III (exoIII), followed by single-strand (ss) selective DNA modification by a complex of osmium tetroxide with 2,2'-bipyridine. In double-stranded DNA possessing free 3'-ends, the exoIII creates ss regions that can accommodate the electroactive osmium marker. Intensity of the marker signal measured at the pyrolytic graphite electrode responded well to the extent of DNA damage. The technique was successfully applied for the detection of (1) single-strand breaks (ssb) introduced in plasmid DNA by deoxyribonuclease I, and (2) apurinic sites generated in chromosomal calf thymus DNA upon treatment with the alkylating agent dimethyl sulfate. The apurinic sites were converted into the ssb by DNA repair endonuclease activity of the exoIII enzyme. We show that the presented technique is capable of detection of one lesion per approximately 10(5) nucleotides in supercoiled plasmid DNA.     

OPLC Comparison of Methods for Aqueous Extraction of Sennae folium and Tiliae flos Plant Samples

JPC – Journal of Planar Chromatography – Modern TLC - A new, simplified open-vessel microwave extraction (OVME) method has been used to prepare aqueous extracts of Sennae folium and...     

Fully On-Line Hyphenation of an Experimental OPLC Separation Unit with Diode-Array Detection and Mass-Spectrometry (OPLC-DAD-MS) for Analysis of Xanthine Compounds

JPC – Journal of Planar Chromatography – Modern TLC - The newly developed experimental OPLC separation unit 100 (OSU 100) has been used for fully on-line multiple hyphenation using the...     

GlycoMiner: a new software tool to elucidate glycopeptide composition

New computer software, GlycoMiner, has been developed to automatically identify tandem (MS/MS) spectra obtained in liquid chromatography/mass spectrometry (LC/MS) runs which correspond to N-glycopeptides. The program complements conventional proteomics analysis, and can be used in a high-throughput environment. The program interprets the spectra and determines the structure of the corresponding glycopeptides. GlycoMiner runs under Windows, can process spectra obtained on various instruments, and can be downloaded from our website (w3.chemres.hu/ms/glycominer). The algorithm works similarly to a human expert; evaluates the low mass oxonium ions; deduces oligosaccharide losses from the protonated molecule; and identifies the mass of the peptide residue. The program has been tested on tryptic digests of two glycopeptides: AGP (which has five different N-glycosylation sites) and transferrin (with two N-glycosylation sites). Results have been evaluated both manually and by GlycoMiner. Out of 3132 MS/MS spectra 338 were found to correspond to glycopeptides; identification by GlycoMiner showed a 0.1% false positive and 0.1% false negative rate. From these it was possible to identify 196 glycan structures manually; GlycoMiner correctly identified all of these, with no false positives. The rest were low quality spectra, not suitable for structure assignment.