Nachweis von Halogen-nitrobenzolen

Zusammenfassung Halogen-dinitro und -mononitrobenzole geben in alkoholischer Lauge mit nukleophilen Reagenten Farbreaktionen. Mit Hydroxylionen bzw. Pyridin, Chinolin, Dioxan, Hydroxylamin und Hydrazin entstehen Säure-Base-Indikatoren. Am schnellsten verläuft die Reaktion mit 2,4-Dinitrofluorbenzol, weniger rasch mit der entsprechenden Chlorverbindung. p-Nitrochlorbenzol reagiert entweder gar nicht oder nur sehr schwach. Auf dieser Grundlage kann man sowohl Halogen-dinitrobenzole von Halogen-mononitrobenzolen unterscheiden als auch kleine Mengen Halogen-dinitrobenzol neben Halogen-mononitrobenzol nachweisen.

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Summary Color reactions are given in alcoholic caustic alkali solutions with nucleophilic reagents by halogen dinitro and halogen mononitrobenzenes. Acid-base indicators result with hydroxyl ions or with pyridine, quinoline, dioxane, hydroxylamine, hydrazine. The reaction with 2,4-dinitrofluorobenzene proceeds most quickly, less rapidly with the corresponding chlorine derivative. p-Nitro-chlorobenzene does not react at all or to a very slight extent. These findings constitute the basis of a differentiation of halogendinitrobenzenes from halogenmononitrobenzenes, and small amounts of halogendinitro benzene can be detected in this way in the presence of halogenmononitrobenzene.

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Résumé Les halogéno, dinitro et mononitrobenzénes donnent des réactions colorées avec les réactifs nucléophiles en lessive alcoolique. Avec les ions hydroxyles ou avec la pyridine, la quinoléine, le dioxane, l'hydroxylamine et l'hydrazine, des indicateurs acides-bases prennent naissance. La réaction avec le dinitro-2,4 flourobenzène est la plus rapide, elle est moins rapide avec le composé chloré correspondant. Le p-nitrochlorobenzène ne réagit pas du tout ou très faiblement. On peut en s'appuyant sur ce fait, aussi bien distinguer les dinitrohalogénobenzènes des mononitrohalogénobenzènes, que rechercher de petites quantités de dinitrohalogénobenzènes en présence de mononitrohalogénobenzènes.

     

Nachweis von Oxoverbindungen

Zusammenfassung Nitroderivate der Oxoverbindungen geben mit Phenylhydrazin und Essigsäure eine Farbreaktion; damit können sie nachgewiesen werden. Oxydiert man Phenylhydrazone mit Kaliumbromat in salzsaurem Milieu, so verhalten sie sich verschieden. Auf der Basis dieses Verhaltens können Formaldehyd neben Acetaldehyd, Acetaldehyd neben Aceton undgr" align="BASELINE" BORDER="0">-Chloracetophenon neben Acetophenon nachgewiesen werden. p-Nitrophenylhydrazone von Aldehyden sind Säure-Base-Indikatoren. Auf der Grundlage dieser Indikatorwirkung kann man Aldehyde unterscheiden. Werden p-Nitrobzw. 2,4-Dinitrophenylhydrazone oxydiert, so verhalten sie sich verschieden. Auf der Basis dieser Oxydationsreaktion kann man Acetaldehyd neben Formaldehyd nachweisen.

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Summary Nitro derivatives of the oxo compounds give a color reaction with phenylhydrazine and acetic acid; this finding serves as a method of detection. If phenylhydrazones are oxidized with potassium bromate in hydrochloric acid milieu, they show different behaviors. This behavior serves as the basis of detecting formaldehyde in the presence of acetaldehyde, acetaldehyde in the presence of acetone, andgr" align="BASELINE" BORDER="0">-chloroacetophenone in the presence of acetophenone. Thep-nitrophenylhydrazones of aldehydes are acid-base indicators. Aldehydes may be differentiated on the basis of this indicator action. Ifp-nitro-or 2,4-dinitrophenylhydrazones are oxidized, they show divergent behaviors. Acetaldehyde can be detected in the presence of formaldehyde on the basis of this oxidation reaction.

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Résumé Les dérivés nitrés des composés oxo donnent avec la phénylhydrazine et l'acide acétique une réaction colorée, ce qui permet leur recherche. Si l'on oxyde des phénylhydrazones par le bromate de potassium en milieu chlorhydrique, elles se comportent différemment. On peut donc rechercher ainsi le formaldéhyde en présence d'acétaldéhyde, l'acétaldéhyde en présence d'acétone et lagr" align="BASELINE" BORDER="0">-chloroacétophénone en présence d'acétophénone. Lesp-nitrophénylhydrazones des aldéhydes sont des indicateurs mixtes. D'après ce comportement, on peut différencier les aldéhydes. Si l'on oxyde lesp-nitro ou dinitro-2,4-phénylhydrazones, elles se comportent d'une manière différente. En mettant à profit cette réaction d'oxydation, on peut rechercher l'acétaldéhyde en présence de formaldéhyde.

     

What is so special with the powerset operation?

The powerset operator, , is an operator which (1) sends sets to sets,(2) is defined by a positive formula and (3) raises the cardinality of its argument, i.e., |(x)|>|x|. As a consequence of (3), has a proper class as least fixed point (the universe itself). In this paper we address the questions: (a) How does contribute to the generation of the class of all positive operators? (b) Are there other operators with the above properties, independent of ? Concerning (a) we show that every positive operator is a combination of the identity, powerset, and almost constant operators. This enables one to define what a -independent operator is. Concerning (b) we show that every -independent bounded positive operator is not -like.Mathematics Subject Classification (2000): Primary 03E05, secondary 03E20     

On a class of degenerate potential elliptic system

We study a class of degenerate potential elliptic systems of the form , defined on a bounded or unbounded domain.     

Biomagnetic fluid flow over a stretching sheet with non linear temperature dependent magnetization

The flow of a heated ferrofluid over a linearly stretching sheet is studied in the pres- ence of an applied magnetic field due to a magnetic dipole. It is assumed that the applied magnetic field is sufficiently strong to saturate the ferrofluid and the variation of magnetization with temperature can be approximated by a non linear function of temperature difference. By introducing appropriate non dimensional variables the problem is described by a coupled and non linear system of ordinary differential equations with its boundary conditions which is solved numerically by applying an efficient numerical technique based on the common finite difference method. The obtained results are presented graphically for different values of the parameters entering into the problem under consideration and the dependence of the flow field from these parameters is discussed. A comparative study, with a similar problem which has already been solved and documented in literature, is also made wherever necessary, emphasizing the impor- tance of the non-linear variation of magnetization with temperature. Emphasis is also given in the obtained results for Prandtl number equal to 21 and critical exponent = 0.368 which are important and interesting in Biomagnetic Fluid Dynamics.     

Multiphoton ionization of magnesium in a Ti-sapphire laser field

In this paper we report the theoretical results obtained for partial ionization yields and the above-threshold ionization (ATI) spectra of magnesium in a Ti: sapphire laser field (804 nm) in the range of short pulse duration (20-120 fs). Ionization yield, with linearly polarized light for a 120 fs laser pulse, is obtained as a function of the peak intensity motivated by recent experimental data [9]. For this, we have solved the time-dependent Schrödinger equation nonperturbatively on a basis of discretized states obtained with two different methods; one with the two-electron wavefunction relaxed at the boundaries, giving a quadratic discretized basis and the other with the two-electron wavefunction expanded in terms of Mg ⁺ -orbitals plus one free electron allowing the handling of multiple continua (open channels). Results, obtained with the two methods, are compared and advantages and disadvantages of the open-channel method are discussed.Received: 17 June 2003, Published online: 26 August 2003PACS: 32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states)G. Buic-Zloh: Permanent address: Institute for Space Sciences, P.O. Box MG-23, 76900 Bucharest-Mgurele, Romania.     

On the role of harmonics superimposed to the driving field in a harmonic generation process

The spatially integrated emission of harmonics from two along the propagation axis spatially separated sources has been investigated as a function of the relative phase and relative emission power of the two sources. Temporal interference fringes have been observed with frequency distributions including multiples of the driving Ti:sapphire laser frequency. The interference fringes provide evidence of harmonic emission that is sensitive to the relative emission phases and intensities of the two sources. Thus they demonstrate control of the emission at the following source by the harmonics emitted at the preceding one. The observed interference frequencies are discussed qualitatively and some of them are attributed to resonant processes.     

Thermal analysis of blast furnace stove regenerators system operating under staggered cold-bypass arrangement by computer simulation

A system of blast furnace stove regenerators operating under the "staggered with cold by-pass" arrangement is analyzed. The solution of the partial differential equations, which govern this non-linear heat transfer process, via computer simulation, is presented. The temperature dependence of the solid and fluid properties and heat transfer coefficients is taken into account. An example demonstrates the usefulness of the method, and the comparison with two other stove arrangements, the "series parallel", and "staggered", presented earlier, are discussed. It is shown, how this method can be utilized to aid the stove design, or to improve the performance of existing installations.     

On separating conformal annuli and Mori’s ring domain in ℝ<Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

Given four pointsa, b, c, d inℝ ⁿ we find the conformal annulus of minimal capacity which separatesa, b fromc, d. This result shows that a conjecture of M. Vuorinen is true. We also give an upper bound for the capacity of Mori’s ring domain in ℝ ⁿ .     

Nachweis ein- und mehrwertiger Phenole

Zusammenfassung Phenolderivate kann man auf der Basis ihrer Indikatorwirkung und des Säure-Base-Charakters ihrer Kupplungsprodukte mit diazotierter Sulfanilsäure unterscheiden. Brenzcatechin und Hydrochinon werden mit Lauge gefärbt. Phenol, Brenzcatechin und Resorcin liefern bei saurer Kupplung in Anwesenheit von Natriumacetat Säure-Base-Indikatoren, aber Hydrochinon nur bei alkalischer Kupplung; Phloroglucin gibt keinen Indikator. Die Wirkung und die strukturelle Veränderung der so gewonnenen Indikatoren sind ähnlich wie bei Nitrophenolen.gr" align="BASELINE" BORDER="0">- und-Naphthol kann man auf der Basis der Säure-Base-Indikatorwirkung der mit Natriumnitrit entstandenen Nitrosoverbindungen unterscheiden.

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Summary Phenol derivatives can be differentiated on the basis of their indicator action and the acid-base character of their coupling products with diazotized sulfanilic acid. Pyrocatechol and hydroquinone yield a color with alkali. Phenol, pyrocatechol, and resorcin yield acid-base indicators through acid coupling in the presence of sodium acetate, but hydroquinone only on alkaline coupling. Phloroglucinol yields no indicator. The action and the structural alteration of the indicators produced in this manner are similar to those in the case of nitrophenols. 1-naphthol and 2-naphthol can be differential on the basis of the indicator action of the nitroso compounds produced with sodium nitrite.

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Résumé On peut distinguer les dérivés phénoliques d'apr&egrave;s leur action comme indicateur et le caract&egrave;re acide-base de leur produit de copulation avec l'acide sulfanilique diazoté. Le pyrocatéchol et l'hydroquinone se colorent par la soude. Le phénol, le pyrocatéchol et le résorcinol conduisent par copulation acide en présence d'acétate de sodium &agrave; des indicateurs acide-base, mais l'hydroquinone seulement par copulation alcaline; le phloroglucinol ne donne pas d'indicateur. L'action et le changement de structure de ces indicateurs sont analogues pour les nitrophenols. L'gr" align="BASELINE" BORDER="0">-naphtol et le-naphtol on peut distinguer d'apr&egrave;s l'action comme indicateur des composés nitroso formés avec le nitrite de sodium.