Wyniki wyszukiwania - Biblioteka Nauki

1

Faza gazowa w szkle. Cz. II.

100%

Kuśnierz A.

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2004

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tom R. 55, nr 6

26-27

PL

Badano rozpuszczalność gazów w szkłach. Próbki o różnym składzie chemicznym i różnej zawartości środków klarujących analizowano przy użyciu metody chromatografii gazowej. Przedstawiono rezultaty wstępnych pomiarów dla wybranych próbek szkieł topionych w temperaturze 1450 stopni C oraz czasie topienia 4 godzin. Różna ilość wyekstrahowanych składników gazowych w porównaniu ze szkłem bazowym wskazuje, że efektywność zastosowanych środków klarujących jest zróżnicowana. Najsilniejszy efekt klarujący uzyskuje się stosując mieszankę As2O3. Sb2O3, NaNO w proporcjach 1 : 1 : 1.

EN

The solubility of gases in glass was investigated. The samples of glasses of different chemical composition and with content of different fining agents were melted and examined by using gas chromatography method. The results of the initial measurements for selected samples of glasses melted at a temperature of 1450 degrees C for 4 hours. The varied amounts of gasseous components extracted, in relation to the reference glass, indicates that the fining effectivity of the refining agents had been applied was strongly differentiated. The strongest refining effect was obtained with a mixture of As2O3. Sb2O3, NaNO in a rate 1 : 1 : 1.

2

Wielkości termodynamiczne do opisu zachowania się fazy gazowej

100%

Warowny W.

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2007

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tom Nr 11

5-11

EN

Various thermodynamic expressions are necessary (including: residual and departure thermodynamic functions, fuga-city, Joule-Thomson coefficient, isentropic exponent, velocity of sound, and so on) for description of the physical processes in the gas phase, under pressure. Predicting of the gas phase behavior is important in the gas industry, so the majority of volumetric calculations carried out are based on the compressibility factor and equations of state.

3

1H and 13C Nuclear Magnetic Shielding in Gaseous and Liquid Propene

100%

Kubiszewski M. , Makulski W.

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2008

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tom Vol. 82, nr 7

1457-1457

EN

Propylene, C3H6, was studied by high resolution NMR spectroscopy in liquid and gaseous state at 300 K. Extrapolation of gas-phase 1H and 13C chemical shifts to the ero-den sity limit permit ted the determinations of absolute nuclear magnetic shielding in the isolated propylene molecule. These new experimental results were used in a reliable verification of ab in itio calculations of proton and carbon nuclear magnetic shielding. The analogous pure liquid propylene spectra were also measured. The second virial coefficients and gas-to-liquid shifts were discussed in the context of intermolecular inter actions in gas and association in liquid phase.

4

Change of Prototropic Equilibria for Uracil when Going from Neutral Molecule to Charged Radicals. Quantum-Chemical Studies in the Gas Phase

75%

Raczyńska E. D. , Zientara K. , Kolczyńska K. , Stępniewski T. M.

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2009

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tom Vol. 83, nr 5

821-834

EN

To understand various substitution, oxidation or degradation reactions for uracil, quantum-chem i calcalculations were performed for two classes of charged radicals (cations and anions) of uracil (U+ź and U-ź) and model compounds: phenol (P+ź and P-ź) and hydroxyazines (HP1-4+ź and HP1+-4-ź). In calculations, all possible eighteen prototropic tautomers-rotamers of U and all possible five prototropic tautomers-rotamers of P and HP1-4 were considered. Stabilities, internal effects and aromatic character, estimated for charged radicals, were compared with those observed previously for neutral molecules. The great est changes of the tautomeric preferences take place for radical anions. One-electron reduction stabilizes the keto and amide functions in studied compounds, whereas one-electron oxidation favors the enol function for ph nol and the amide function for uracil and hydroxyazines.

5

The Nature of Hydrogen Bonding in Selected Hydrazide Derivatives Investigated via Static Models and Car-Parrinello Molecular Dynamics

75%

Jezierska A. , Novič M. , Panek J. J.

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2009

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tom Vol. 83, nr 5

799-819

EN

The geometric and spectrocopic properties of 2-hydroxy-thiobenzhydrazide and 2-hydroxy-benzhydrazide were investigated within the frame work of Density Functional Theory (DFT). Special attention was devoted to the description and analysis of intra- and intermolecular hydrogen bonds. The choice of the compounds was dictated by their structural similarity and the presence of two types of hydrogen bridges: O–H...S (in 2-hydroxy-thiobenzhydrazide, less common) and O–H...O (in 2-hydroxy-benzhydrazide). The latter could be classified as a low-barrier hydrogen bond (LBHB). First the DFT method was used to obtain the geometric parameters for the monomeric and dimeric forms of the compounds at various levels of theory. Then the binding energy was calculated for the dimeric forms to estimate the strength of the intermolecular hydrogen bonds. Atoms in Molecules (AIM) theory was applied to show quantitatively how the formation of the intermolecular hydrogen bonds affects the strength of the intramolecular hydrogen bonds. The electron density and its Laplacian were calculated for the bond critical points defining the H-bridges. Car-Parrinello molecular dynamics (CPMD) was then used to investigate the changes in the geometric parameters as a function of simulation time. This part of the computational study was performed in vacuo and in the solid state. The vibrational properties of the investigated hydrazides were obtained via Fourier transform of the autocorrelation functions of the dipole moment and atomic velocity. It was found that the formation of the intermolecular H-bonds does not significantly affect the strength of the intramolecular H-bonds. There fore inductive and steric effects out side the immediate vicinity of the intramolecular bridge have minor influence on its investigated properties. The application of CPMD gave a more detailed picture of the bridged protons’ dynamics. The computational results agree with available experimental data. The influence of the intermolecular hydrogen bonding net work and non-bonded crystal field interactions on the vibrational features of the investigated molecules is demonstrated and discussed.

6

Zastosowanie równań stanu do opisu fazy gazowej i równowag fazowych

75%

Warowny W. , Sarnecki D.

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2007

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tom Nr 10

9-13

EN

The role of equations of state in describing gas phase and liquid: steam phase equilibrium in perfect gas and in real gas. Conditions for applying a few selected equations of state. Examples of using equations of state in gas industry, with natural gas.

7

Opis fazy gazowej w pirolizie biomasy za pomocą równowagi termodynamicznej

63%

Warowny W. , Celińska A.

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2008

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tom Nr 7-8

9-13

EN

The purpose of this paper was to evaluate thermodynamic equilibrium characteristics of gaseous phase after pyrolysis of birch and palm. Results of calculations provide clearer insight into several parameters on the gas produced by pyrolysis of studied biomasses.

8

Problemy dezodoryzacji metodą ozonowania w fazie gazowej

63%

Tatoj P.

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2002

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tom Nr 1

20-21

PL

Omówiono rezultaty badań dezodoryzacji metodą ozonowania w fazie gazowej wybranych odorantów: olejków lawendowego, goździkowego i różanego oraz trietyloaminy, alkoholu etylowego i izoamylowego, octanu etylu i toluenu. Wykazano, że wysoka skuteczność procesu wymaga dużych nadmiarów ozonu i długich czasów kontaktu oraz, że w produktach reakcji pojawiają się nowe związki chemiczne, których jednak nie identyfikowano. Uzyskane wyniki wskazują, że dezodoryzację metodą ozonowania w fazie gazowej można stosować tylko w specyficznych warunkach, po przeprowadzeniu dokładnych badań wstępnych określających parametry procesu i przy pełnej identyfikacji powstających produktów reakcji. Jednak nawet w takich przypadkach należy się liczyć z problemami natury technicznej i ekonomicznej. Z przesłanek tych wynika, że dez-odoryzacja metodą ozonowania w fazie gazowej nadaje się do aplikacji tylko w specyficznych warunkach, kiedy inne metody zawodzą.

EN

The experimental results dealing with deodorization using the ozonization method in gas phase for selected odorants such as: lavender, clove and rose oils, triethylamine, ethanol, isoamyl alcohol, ethyl acetate and toluene have been discussed. It has been proved that a high process efficiency required large ozone overdoses and long contact time and new substances appeased in reaction products. However, these substances have not been identified. The results indicate that the ozonization in gas phase can be used only in the specific conditions, after precise initial tests determining process parameters and reaction products. Even for these cases, some technical and economical issues can be encountered. In the light of circumstances presented, one can stated that deodorization using the ozonization method in gas phase is applicable only in specific conditions, when other methods are inappropriate.

9

Współczynnik dyfuzji w fazie gazowej : porównanie wybranych korelacji

63%

Thullie J. , Bodzek M.

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2003

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tom Nr 4

12-15

PL

W pracy przedstawiono porównanie różnych korelacji dla określania wartości binarnych współczynników dyfuzji w gazach. Stwierdzono, że zalecany powszechnie wzór Fullera nie zawsze przewiduje właściwe wartości. Przedstawione wyniki sugerują stosowanie korelacji Hirschfeldera bądź Slattery'ego.

EN

A comparison of different correlations for calculation binary diffusion coefficient in gases is shown. It has been stated that the widely used Fuller equations do not predict correct values. Therefore, based on the results presented, one suggests the use of the Hirschfelder or Slattery correlations.