The problem of identifying an adequate kinetic equation for a chemical transformation in thermal analysis

Additional criteria are suggested for the selection of an adequate functiong() describing the mechanism of a chemical transformation using the Satava method.

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Zusammenfassung Zusätzliche Kriterien werden zur Auswahl der geeigneten Funktion g() zur Beschreibung des Mechanismus der chemischen Umwandlung mit der Satava-Methode vorgeschlagen.

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g() .

     

Some supplementary data on particular features of the thermal behaviour of potassium persulfate

The effects of preliminary mechanical activation and thermal treatment of potassium persulfate on the thermal and electrical characteristics of its thermal decomposition were studied by DTA, TG, evolved gas volumetry and high-frequency thermal analysis.

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Zusammenfassung Die Wirkungen von einer vorausgehenden mechanischen Aktivierung und der thermischen Behandlung von Kaliumpersulfat auf die thermischen und elektrischen Charakteristika der Zersetzung dieser Verbindung wurde mittels DTA, TG, volumetrische Messung des freigesetzten Gases und thermische Hochfrequenz-Analyse untersucht.

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, , .

     

A solution of the exponential integral in the non-isothermal kinetics for linear heating

A simple and satisfactorily accurate solution of the exponential integral in the nonisothermal kinetic equation for linear heating is proposed: $$\mathop \smallint \limits_0^T e^{ - E/RT} dT = \frac{{RT^2 }}{{E + 2RT}}e^{ - E/RT} $$      

Friedmann cosmology with nonpositive-definite Higgs potentials

We consider classical aspects of the dynamics of scalar fields with nonpositive-definite potentials in the Friedmann cosmology. Such models appear as effective local models in the framework of nonlocal models related to string field theory. In an effective local approximation after a suitable field redefinition, the Higgs potential with a negative effective cosmological constant appears in these models. A special feature of considered models is an absence of the reheating phase, instead of which phase of regime change from expansion to contraction appears. We study the behavior of the model near the point of regime change.     

An estimate of an optimal argument in the sharp multidimensional Jackson-Stechkin <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript>-inequality

An estimate of an optimal argument in the sharp Jackson-Stechkin inequality in the space L ₂(? ⁿ ) is proved in the case of a generalized modulus of continuity; its special case is the classical modulus of continuity. Similar statements hold for the torus \(\mathbb{T}^n \). The obtained results agree with Chernykh’s classical one-dimensional theorems and refine some results by S.N. Vasil’ev, A.I. Kozko, and A.V. Rozhdestvenskii.     

Measuring the activity of a <Superscript>51</Superscript>Cr neutrino source based on the gamma-radiation spectrum

A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of ⁵¹Cr is presented.     

Approximation in <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript> by Partial Integrals of the Multidimensional Fourier Transform over the Eigenfunctions of the Sturm–Liouville Operator

For approximations in the space L₂(?₊ ^d ) by partial integrals of the multidimensional Fourier transform over the eigenfunctions of the Sturm–Liouville operator, we prove the Jackson inequality with sharp constant and optimal argument in the modulus of continuity. The multidimensional weight that defines the Sturm–Liouville operator is the product of onedimensional weights. The one-dimensional weights can be, in particular, power and hyperbolic weights with various parameters. The optimality of the argument in the modulus of continuity is established by means of the multidimensional Gauss quadrature formula over zeros of an eigenfunction of the Sturm–Liouville operator. The obtained results are complete; they generalize a number of known results.     

Transmission of quantum correlations of light into atoms

JETP Letters - The interaction between two broadband modes of a parametric source of light and two atoms located at different positions has been considered. As follows from the obtained Bell...     

Using FTIR spectroscopy to detect sericin on historic silk

Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide.Their optimum preservation demands an appreciation of their characteristics.One important concern,especially with regard to ancient Chinese silks,is whether the fabrics have been degummed.Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol.In previous research on aged silks,the presence of sericin has been inferred from amino acid analysis of hydrolysa...     

Amplification of entangled light upon reflection from a cavity with nonlinear medium

The kinetic equation for the case of reflection of a broadband entangled light of a nondegenerate parametric source from a cavity is derived with the use of the technique of stochastic differential Ito equations. Statistical properties of the light reflected from a cavity with a nonlinear transparent medium, in which the process of special parametric interaction occurs, are considered on the basis of the obtained equation. Due to the integrals of motion, the entangled light, which is an EPR pair of continuous variables, can be amplified without destruction of the quantum correlation.