Comparative study on inclusion complexations of antiinflammatory drug flurbiprofen with β-cyclodextrin and methylated β-cyclodextrins

Abstruct Some physicochemical properties of methylated -cyclodextrins, i.e., heptakis(2,6-di-O-methyl)--cyclodextrin (DM--CyD) and heptakis(2,3,6-tri-O-methyl)--cyclodextrin (TM--CyD) were compared with those of natural -cyclodextrin (-CyD). Inclusion behaviors of -CyD and methylated -CyDs in water and in solid state were studied by solubility analysis, spectroscopies (UV, CD,¹³C-NMR and IR), X-ray diffractometry and thermal analysis, using an antiinflammatory drug flurbiprofen (FP) as a guest molecule. The spectral data suggest that the inclusion mode of FP-TM--CyD is somewhat different from those of FP--CyD and FP-DM--CyD. The solid complexes of FP with - and methylated -CyDs were obtained in molar ratio of 11, and their dissolution behavior and release from suppository base were examined. The data are presented suggesting that DM--CyD is particularly useful for improving the pharmaceutical properties of FP in various dosage forms.     

Chemiluminescent method to measure generation rates of active centers in reaction of hydrogen peroxide with hemin and pyridinehemichrome

A chemiluminescent method was used to measure generation rates of active intermediates in the interaction of hemin with hydrogen peroxide with and without pyridine at pH=8–9. The effect of various inhibitors in these two cases has been examined.

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pH=8+9. .

     

Reduction of photohemolytic activity of benoxaprofen byβ-cyclodextrin complexations

Inclusion complexations of benoxaprofen (BXP) with-cyclodextrin (-CyD) and heptakis (2,6-di-O-methyl)--CyD (DM--CyD) were studied by the solubility method and CD and¹H-NMR spectroscopy. Both -CyDs decelerated the photodecarboxylation of BXP, and suppressed the BXP-photosensitized hemolysis, where the inhibitory effect of DM--CyD was larger than that of -CyD. This order was well correlated with the magnitude of the stability constants of BXP--CyD complexes. The peroxidation of lipid components in erythrocyte ghosts induced by BXP was also suppressed particularly by DM--CyD. The protective effect of -CyDs on the BXP-induced photohemolysis seems to be due to the suppression in the photochemical reactions of BXP yielding toxic transient species, together with the inhibition in attacks of the transient species to the membrane, through inclusion complexation.     

Effect of bond energies of a catalyst with reacting atoms on the selectivity of CO hydrogenation over metals

In hydrogenation over metals (M)_j carbon monoxide is adsorbed as a molecule. C–O bond rupture in partially hydrogenated complex, MCHOH, leads to MO and MCH₂ and then to hydrocarbons, while transformation of MCHOH into MCH₂OH gives alcohols and other oxygen-containing compounds. Selectivity towards hydrocarbons increases with increasing energy of M–O bonds.

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(M) . C–O MCHOH MO MCH₂ — ; MCHOH MCH₂OH . M–O.

     

Some Pharmaceutical Properties of a New Branched Cyclodextrin, 6-O-α-(4-O- α-D-Glucuronyl)-D-glucosylβ-cyclodextrin

Some physicochemical and biological properties of a new branched cyclodextrin, 6-O--(4-O--d-glucuronyl)-d-glucosyl--cyclodextrin GUG--CyD) were investigated. Further, theinteraction of GUG--CyD with several drugs was studied by the solubility and spectroscopic methods, and compared with those of parent -CyD and 6-O--maltosyl--CyD(₂--CyD).The hemolytic activity of GUG--CyD on rabbit erythrocytes was lower than those of -CyD and ₂--CyD. GUG--CyD and ₂--CyD showed negligible cytotoxicity on Caco-2 cells up to at least 0.1 M. The inclusion ability of GUG--CyD to neutral and acidic drugs was comparable to or slightly smaller than those of -CyD and ₂--CyD, probably because of a steric hindrance of the branched sugar. On the other hand, GUG--CyD showed greater affinity for the basic drugs, compared with -CyD and ₂--CyD, owing to the electrostatic interaction of its carboxylate anion with positive charge of basic drugs. Thus GUG--CyD may be useful as a safe solubilizing agent particularly for basic drugs.     

Variations in electronic state of silver catalysts for methanol oxidation

Variations in the electronic state of silver catalysts for methanol oxidation under the effect of the reaction medium have been studied, using diffuse reflectance spectroscopy. The nature of active centers-Ag⁺ cations, Ag _n ⁺ complexes and clusters of various sizes for bulk and supported catalysts are shown to be identical.

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. - Ag⁺, Ag _n ⁺ .

     

Study of the thermal decomposition of solids in a fluidized bed, III

The influence of the air humidity upon the thermal decomposition of diammonium hydrogen phosphate was studied in a fluidized bed, under isothermal conditions. It was found that the increase of the decomposition rate is influenced directly by the partial pressure of the water vapour in the air, and indirectly by the working temperature. The moisture effect is explained by the salt hydrolysis in the water condensed on the grain surface. The energy of activation of the thermal decomposition decreases when the air humidity increases.

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Zusammenfassung Der Einfluß der Luftfeuchtigkeit auf die thermische Zersetzung des Diammoniumhydrogenphosphats wurde in fluidisiertem Bett unter isothermen Verhältnissen studiert. Die Zunahme der Zersetzungsgeschwindigkeit war direkt proportional dem partialen Wasserdampfdruck in der Luft und indirekt proportional der Arbeitstemperatur. Diese Wirkung wird durch Salzhydrolyse in dem kondensierten Wasser an der Kernoberfläche erklärt. Die Aktivierungsenergie der thermischen Zersetzung nimmt mit zunehmendem Feuchtigkeitsgehalt ab.

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Résumé On a étudié l'influence de l'humidité atmosphérique sur la décomposition thermique de (NH₄)₂HPO₄ en lit fluidisé, en conditions isothermes. La pression partielle de la vapeur d'eau dans l'air intervient directement sur l'augmentation de la vitesse de décomposition et exerce une action indirecte sur la température de travail. On a expliqué l'effet de l'humidité par l'hydrolyse du sel dans l'eau condensée à la surface des grains. La valeur de l'énergie d'activation de la décomposition thermique diminue quand l'humidité atmosphérique augmente.

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. , , , , . , .

     

Sintering of supported palladium

Sintering results of Pd supported on carbon black at 723–973 K, in water vapor, in H₂ and under high vacuum are reported. They are compared with sintering data of Pd on other supports. The observed sequences are: SiO₂C>sepioliteAl₂O₃>AlPO₄ and H₂O>high vacuum>H₂.

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Pd 723–973 , , H₂ . Pd . : SiO₂Al₂O₃>AlPO₄ H₂O> >H₂.

     

Determination of reaction kinetic parameters from variable temperature DSC or DTA

An equation is derived for evaluating the kinetic parameters of a transformation from variable temperature DSC or DTA, taking account of the variation in the reaction rate constant with time and temperature. Kinetic parameters for the crystallization of a ZrF₄-BaF₂-LaF₃ glass are calculated using this equation.

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Zusammenfassung Es wird eine Gleichung zur Bestimmung der kinetischen Parameter einer Umwandlung aus DSC- und DTA-Messungen bei variabler Temperatur abgeleitet, die den Veränderungen der Reaktionsgeschwindigkeit mit der Zeit und der Temperatur Rechnung trägt. Kinetische Parameter der Kristallisation von ZrF₄-BaF₂-LaF₃-Glas werden unter Benutzung dieser Gleichung berechnet.

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, , . , ZrF₄-BaF₂-LaF₃.

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This work was carried out under a grant from the National Aeronautics and Space Administration, Materials Processing in Space Program.     

A thermal X-RAY and resistivity study of the heusler alloy Cu2NiSn

The compound Cu₂NiSn was analyzed by DTA, X-ray and electrical resistivity measurements. No single-phase structure was found at room temperature. The alloy decomposes upon heating, starting at 160°, forming copper and two hcp structures. At 500° the Heusler structure is restored. Electrical resistivity results are discussed in terms of Markowitz's theory for disordered metals.

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Zusammenfassung Die Verbindung Cu₂NiSn wurde durch DTA, Röntgen- und elektrische Widerstandsmessungen analysiert. Keine Einphasenstruktur wurde bei Zimmertemperatur gefunden. Die Legierung zersetzt sich beim Erhitzen ab 160°, wobei Kupfer und zwei hcp-Strukturen gebildet werden. Bei 500° wird die Heusler-Struktur wieder hergestellt. Die Ergebnisse der elektrischen Widerstandsmessungen werden aufgrund der Markowitzschen Theorie für ungeordnete Metalle diskutiert.

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Résumé Le composé Cu₂NiSn a été examiné par ATD, rayons X et mesures de résistance électrique. A température ambiante on n'a pas trouvé de structure correspondant à une phase unique. L'alliage se décompose par chauffage à partir de 160° en formant du cuivre et deux structures hcp. A 500° la structure Heusler est rétablie. On discute les résultats des mesures de résistance électrique à partir de la théorie de Markowitz pour des métaux désordonnés.

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Cu₂NiSn , . . , 160° . 500° . a .

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Work supported in part by Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) and Financiadora de Estudos e Projetos (FINEP).     

Multiple rate resonance phenomena in the forced composition cycling of the Fischer-Tropsch synthesis over a supported cobalt oxide catalyst

Experimental investigation of hydrocarbon synthesis from a mixture of CO and H₂ over a supported cobalt oxide catalyst showed pronounced resonance of the rate of formation of individual hydrocarbons with respect to the frequency of the feed compositon changes. When the measured concentrations of the synthesis products are time-averaged, the mean rate of formation for methane increases fivefold when compared with rate at the mean composition of the feed at steady state for a cycling frequency of 0.017 c/s. Another maximum occurs at about 0.00056 c/s, where the mean rate is about twice the steady-state rate. Rate resonance was also observed for higher hydrocarbons at similar frequencies but with smaller time-average rates. Resonance of rates of reaction has been observed for other catalysts, but rarely with multiple peaks and with such large magnitudes of the rate change.

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CO H₂ . , 0,017 /. 0,00056 /, . , , . , .

     

Kinetic analysis of thermogravimetric data XIX. Study of the thermal decomposition of some hexathiocyanatochromates

Ammonium and metal salts of the acid H₃[Cr(NCS)₆] have been obtained and characterized. Their thermal decomposition has been studied with a derivatograph. The thermal decomposition of the ammonium salts begins with an endothermic stage, leading to the formation of the intermediate Cr(NCS)₃, which in exothermic processes finally yields Cr₂O₃. The decomposition of the metal salts is exothermal and the polarizing effect of the cation plays an important part in this. Kinetic parameters have been derived by means of the nomogram method.

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Zusammenfassung Ammonium- und Metallsalze der Säure H₃[Cr(NCS)₆] wurden hergestellt und charakterisiert. Ihre thermische Zersetzung wurde mit einem Derivatographen verfolgt. Sie beginnt beiden Ammoniumsalzen mit einer endothermen Phase, welche zur Bildung des Zwischenprodukts Cr(NCS)₃ führt, das in exothermen Vorgängen als Endprodukt Cr₂O₃ ergibt. Die Zersetzung der Metallsalze ist exotherm und der Polarisationseffekt des Kations spielt hierbei eine wichtige Rolle. Kinetische Parameter wurden nach der Nomogramm-Methode abgeleitet.

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H₃[Cr(NCS)₆]. . , Cr(NCS)₆, ₂₃. .

     

Some peculiarities in ESR spectra of titanium complexes in catalysts for isoprene polymerization in excess A1R3

It has been established that at low temperatures of TiCl₄+AOC catalyst preparation in solution (with Ti/Al1/15), ESR spectra exhibit rhombic anisotropy of the g-factor. Experiments with the sample having 61 % concentration of⁴⁷Ti isotopes suggest the formation of associates of Ti³⁺ with magnetic ordering, apparently due to the Jahn-Teller cooperative effect.

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TiCl₄+ AOC ( Ti/Al1/15) g-. ⁴⁷Ti (61%) Ti³⁺ , , -.

     

Cure behavior of an epoxy-phenolic magnetic recording ink

The curing behavior of an epoxy-phenolic coating containing a thermoplastic additive and iron oxide is described. Cure response was measured on a DuPont 981 Dynamic Mechanical Analyzer (DMA) and a Perkin-Elmer TGS-2 Thermogravimetric Analyzer (TGA). Samples coated onto a glass fiber ribbon were cured isothermally in the DMA, allowed to cool, and then scanned to measure the glass transition and related phenomena. During cure the thermoplastic additive was observed to phase separate, as evidenced by a secondary damping peak near its glass transition temperature. Above 200° oxidative reactions made a major contribution to the crosslink density. Isothermal TG in air and nitrogen showed evidence for oxygen uptake and an oxidative weight loss at temperatures >200°. Iron oxide, oxygen content of the purge gas, and flow rate of the purge gas were observed to affect cure behavior.

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Zusammenfassung Das Aushärtungsverhalten von ein thermoplastisches Additiv enthaltenden epoxy-phenolischen Überzügen wird beschrieben. Die Aushärtung wurde mit einem DuPont 981 Dynamic Mechanical Analyzer (DMA) und einem Perkin-Elmer-TGS-2 Thermogravimetric Analyzer (TGA) gemessen. Auf Glasband aufgebrachte Proben wurden isotherm im DMA ausgehärtet und nach dem Abkühlen aufgeheizt, um die Glastransformation und damit zusammenhängende Phenomäne zu messen. Während des Aufheízens wurde eíne Phasentrennung unter Ausscheidung des thermoplastischen Additivs beobachtet, was durch einen sekundären Dämpfungspeak nahe der Glastransformationstemperatur angezeigt wird. Oberhalb 200° tragen oxydative Reaktionen im größeren Umfang zur Vernetzungsdichte bei. Die isotherme TG in Luft und Stickstoff liefert Beweise für eine Sauerstoffaufnahme und einen oxydativen Gewichtsverlust bei Temperaturen über 200°. Eisenoxid sowie Sauerstoffgehalt und Strömungsgeschwindigkeit des Spülgases beeinflussen das Aushärtungsverhalten.

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, . 981 () - -2 (). , , a , . , . 200° . , , 200°. , , , .

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Presented at 13th NATAS Conference, Philadelphia, PA, September 1984.     

Unimolecular decomposition of CF3OF-calculation by reduced Kassel integral in factorized form

The fall-off curves were calculated for the unimolecular decomposition of the trifluoromethyl hypofluorite at 475.8, 496.9 and 507.3 K by means of the Reduced Kassel Integral in Factorized Form.

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475,8,496,9 507,3 .

     

Etude de la stabilite thermique des ethylates alcalins

Résumé La décomposition thermique des éthylates de Li, Na, K, Rb, Cs et de leurs solvates a été étudiée par thermogravimétrie couplée à un dispositif de microsublimation et par analyse thermique différentielle. La réaction de décomposition thermique des éthylates alcalins est complexe et conduit à la formation simultanée d'hydrogène et d'éthylène; les résidus de décomposition ne correspondent à aucun composé défini.

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The thermal dissociation of Li, Na, K, Rb and Cs alcoholates and their respective solvates has been studied by DTA and TG coupled with a gas analysis device. The reaction of decomposition is complex, and hydrogen and ethylene are evolved. The solid residue is a mixture of several compounds.

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Zusammenfassung Die thermische Zersetzung der Äthylate von Li, Na, K, Rb, Cs und ihrer Solvate wurde durch thermogravimetrische Analyse mit einer Mikrosublimierungsvorrichtung gekoppelt, sowie mit der Differentialthermoanalyse untersucht. Die thermische Zersetzungsreaktion der alkalischen Äthylate ist komplex und führt zur simultanen Bildung von Wasserstoff und Äthylen; die Zersetzungsrückstände entsprechen keiner definierten Verbindung.

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, , , , , . . .

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Nous tenons à remercier la Société ELF-ERAP à Solaize (Rhône) et plus particulièrement Monsieur Finas qui ont eu l'amabilité de nous fournir un mélange étalon de différents hydrocarbures gazeux.     

A variational formulation of the rate equations for closed chemical systems

This paper presents a variational formulation of the kinetic equations corresponding to a closed chemical system.

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, .

     

Effect of the state of vanadium cations on the IR spectra of adsorbed carbon monoxide

ESR and IR-spectrosocpic studies of the effect of the state of vanadium ions on the IR-spectra of adsorbed CO have revealed complex formation of CO with V⁴⁺ (vCO at 2192 and 2205 cm^–1) and V³⁺ (vCO at 2178 and 2185 cm^–1) ions.

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-- - CO. CO V⁴⁺ (vCO 2192, 2205 cm^–1) V³⁺ (vCO 2178, 2185 cm^–1).