Oxygen adsorption on the surface of a polymer containing coordinated cobalt ions

The formation of adsorbed Co³⁺(O ₂ ^– ) species on the surface of a cobaltcontaining polymer has been established by EPR and reflection spectroscopy in the visible region. The experimental results and quantum-chemical calculations indicate electron transfer from cobalt to the antibonding orbitals of oxygen.

---

, , , Co^–3·O ₂ ^– . - .

     

Sulfur resistance of Pd complexes with nitrogen and sulfur ligans in hydrogenation reactions

It has been found that homogeneous Pd complexes with sulfur ligands are by 50–500 times more resistant to thiophene action in hydrogenation reactions than homogeneous and heterogenized ones containing nitrogen ligands.

---

50–500 .

     

Kinetic study of the oxidation of isobutyraldehyde by aqueous chlorine

The kinetics of oxidation of isobutyraldehyde with aqueous chlorine has been investigated in 11.6 vol. % aqueous acetic acid. The reaction is first order with respect to both substrate and chlorine. Molecular chlorine is the principal oxidant. The influence of various factors, e.g. ionic strength, inorganic salts, D₂O and temperature on the initial rate has been studied. The activation parameters have been calculated and a possible mechanism is suggested.

---

11,6% . , . . ( , , D₂O) . .

     

Flavonoids ofPhellodendron sachalinense andPh. amurense

Summary 1. About ten substances of a flavonoid nature have been found in the leaves ofPhellodendron sachalinense (F. Schm.) Sarg. andPh. amurense Rupr.2. The two species of cork tree each contain two new flavonoids, which have been called phelloside and dihydrophelloside. The results of chemical and spectroscopic studies have permitted phelloside to be characterized as the 7,-di-O--D-glucopyranoside of noricaritin and dihydrophelloside as the 7,-di-O--D-glucopyranoside of dihydronoricaritin, the base of which contains kaempferol and aromadendrin.3. Amurensin (the 7--D-glucopyranoside of noricaritin) and icariside-1 (the -O--D-glucopyranoside of noricaritin) have been isolated as intermediates in the stepwise hydrolysis of phelloside; the latter has not been previously found in the Amur and Japanese cork trees.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 2, pp. 77–82, 1968     

Isotope exchange of molecular nitrogen on barium nitride

The activity of barium nitride in the isotope exchange of nitrogen is 2–3 orders of magnitude higher than that of Fe and Ru. In the temperature range from 373 to 673 K the activation energy of exchange is 40 kJ/mol.

---

2–3 Fe Ru. 373–673 40 /.

     

Thermoanalytical characterization of precipitated acids obtained by alkaline permanganate degradation of the kerogen from Aleksinac (Yugoslavia) oil shale

The precipitated acids, obtained by partial stepwise oxidation of Aleksinac (Yugoslavia) shale kerogen, were studied by thermal analysis. Significant differences were observed in the weight loss and the shape of TG curves of precipitated acids from various degradation steps, indicating their structural differences and heterogeneity of the kerogen. The thermal curves of precipitated acids were found to consist of two distinct parts. From IR data it was found that the low-temperature part corresponded to thermal changes of aromatic, and the high-temperature part of aliphatic type structures. These results were in good agreement with chemical analysis (elemental analysis, atomic H/C ratio, total acidity) of the same acids.

---

Zusammenfassung Durch partielle schrittweise Oxydierung von Schieferkerogen (Aleksinac. Jugoslavien) erhaltene präzipitierte Säuren werden thermoanalytisch untersucht. Signifikante Unterschiede wurden im Gewichtsverlust und der TG-Kurvengestalt von nach den einzelnen Abbauschritten erhaltenen präzipitierten Säuren beobachtet, was auf deren strukturelle Verschiedenheit und auf die Heterogenität des Kerogens hinweist. Die thermische Kurven der präzipitierten Säuren weisen zwei sich unterscheidende Abschnitte auf. Aus IR-Daten ergab sich, daß im Tieftemperaturabschnitt thermische Veränderungen von aromatischen, im Hochtemperaturabschnitt dagegen von aliphatischen Strukturen verlaufen. Diese Ergebnisse stimmen mit chemischen Analysendaten (Elementaranalyse, H/C-Atomverhältnis, Gesamtsäure) gut überein.

---

, ( ). , , , . , . , , — . ( , -, ) .

---

---

Paper presented at the World Conference on Thermal Analysis, Madeira (Portugal). 1986.     

Determination of metal particle sizes in supported catalysts by small-angle X-ray scattering technique

Pt/SiO₂ catalysts have been studied by a small-angle X-ray scattering technique without commonly practiced packing of the carrier pores. The obtained Pt particle sizes are in good agreement with chemisorption and electron microscopy data.

---

Pt/SiO₂ . Pt .

     

Validity limits of the superposition principle when applied to reactions the kinetics of which is diffusion controlled

The superposition principle which is commonly used to solve the Smoluchowsky equation can be proved to be unreliable by elementary calculations applied to a particular example. But the practical kinetic consequences are small and usually hidden whithin experimental errors.

---

, , , , . , .

     

Electrochemical Behavior of Epinephrine at a Penicillamine Self-Assembled Gold Electrode,and its Analytical Application

The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode were investigated. The self-assembled electrode shows obvious electrocatalytic activity for the oxidation of epinephrine (EP). In phosphate buffer (pH 7.73), a sensitive oxidation peak was observed at 0.190V with the PCA modified Au electrode. The peak current is proportional to the concentration of EP in the range of 2.0×10^–56.0×10^–4molL^–1 and 5.0×10^–6 2.0×10^–4molL^–1 for cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the detection limits of 1.8×10^–7 and 1.3×10^–7molL^–1, respectively. The possible reaction mechanism is also discussed. The PCA self-assembled monolayer modified gold electrode is highly stable and can be applied to the determination of EP in practical injection samples. Application is simple, rapid and produces accurate results.     

Calorimetric study of oxygen bond strength in the surface layer of manganese dioxide

The heat of oxygen removal from the MnO₂ surface (q_s) during its reduction by carbon monoxide and the heat of reoxidation of the reduced surface by gaseous oxygen (q_s) have been determined by a calorimetric method at 100 and 200°C. At 200°C both q_s and q_s are close to the enthalpy of MnO₂ transformation to Mn₂O₃. At 100°C the reduction of MnO₂ takes place without any distinct formation of a phase of the lower oxide, however, it leads to significant changes in both the surface and the subsurface layer of the oxide.

---

100° 200°C MnO₂ (q_s) (q_s). 200°C q_s, q_s ( ) MnO₂ Mn₂O₃. 100°C MnO₂ , .

     

Influence of molecular weight on the dynamic mechanical properties of poly(methyl methacrylate)

Using a new parallel beam apparatus, the dynamic mechanical properties of poly-(methyl methacrylate) were determined over a wide range of molecular weights (1500< < <600 000). Results showed that the modulus (25 °C) was only slightly dependent on chain length, and equalled 2.3×10⁹ Pa for the highest molecular weight scanned. Simultaneous acquisition of- and-relaxations indicated a decrease inT in accordance with Gibbs' relation, whileT was invariant. BothT =111° andT =40° corroborated previous results from several sources, including dynamic mechanical measurements. Such modulus and glass transition data are essential to the calculation of fracture toughness and to the assessment of radiation damage of acrylic, respectively.

---

Zusammenfassung Unter Anwendung eines neuen Parallelstrahlgerätes wurden die dynamischen mechanischen Eigenschaften von Poly(methylmethacrylat) in einem weiten Molmassenbereich (1500< <600 000) bestimmt. Die Ergebnisse zeigten, daß der Modul (25°) nur wenig von der Kettenlänge abhängig und für die höchste erfaßte Molmasse gleich 2.3× ×10⁹ Pa war. Die gleichwertige Erfassung der- und-Relaxationen zeigte in Übereinstimmung mit der Gibbs-schen Abhängigkeit eine Abnahme vonT währendT unverändert blieb. SowohlT =111° als auchT =40° bestätigten frühere Ergebnisse verschiedenen Ursprungs, dynamische mechanische Messungen mit inbegriffen. Solch ein Modul und Glas-Übergangsdaten sind zur Berechnung der Bruchfestigkeit bzw. zur Bestimmung der Bestrahlungsschäden in Acrylaten unerläßlich.

---

Résumé En se servant d'un nouvel appareil à rayons parallèles, on a déterminé les propriétés mécaniques dynamiques du poly(méthyl-méthacrylate) dans un large intervalle de poids moléculaires (1500< <600 000). Les résultats on montré que le module (25°) ne dépend que peu de la longueur de la chaîne et est égal à 2.3×10⁹ Pa pour le plus haut poids moléculaire étudié. L'acquisition simultanée des relaxations et a indiqué, en accord avec la relation de Gibbs, une diminution deT tandis queT s'avere invariable. Les valeursT =111°et}T =40° ont corroboré toutes deux des résultats antérieurs de diverses sources, y compris des mesures mécanique dynamiques. Un tel module ainsi que les données de la transition vitreuse sont essentiels pour calculer la résistance à la rupture, et pour déterminer les dommages par irradiation des matières acryliques.

---

, (1500 < < 600 000). , (25°) 2.3&#x0445;10⁹ . - - T , T . T =111° T =40° , . .

---

---

This investigation was supported by NIH Research Grant No. DE 02668, RCDA number DE 00052 (R.P.K.), and RFA number DE 05132 (A.R.G.).     

Laser Sintering of SnO2 : Sb Sol-Gel Coatings

Sb doped sol-gel SnO2 single layers (thickness 100 nm) were prepared from alcoholic solution and deposited via a dip coating process on fused silica substrates. The coatings have been sintered at a typical rate of 10–15 cm2/s by CO2 laser irradiation. The laser spot was scanned in one direction at a speed of 15,000 cm/s and the sample was moved in a perpendicular one at a speed up to 250 mm/s. The temperature of the topmost 10 m layer was monitored by a fast pyrometer (s resolution). The following properties of the coatings have been determined: the electrical resistivity , the carrier density n, and mobility , the structure, the thickness, the mesoscopic and micromorphology and the density. The sintering by CO2 laser radiation is mainly a thermal driven process. At T 500°C it allows to obtain coatings with a smaller resistivity (6.8×10–3 cm) than those produced by conventional furnace firing (el2.9×10–2 cm). The results are discussed in terms of particle size and packing density.     

Steroid saponins and sapogenins ofAllium. XVI. Turoside C fromAllium turcomanicum

From a methanolic extract of the bulbs ofAllium turcomanicum Rgl. we have isolated a new furostanol glycoside, turoside C (I). An acid hydrolysate was found to contain the aglycone — neoagigenin (II) — and the sugars D-xylose, D-glucose, and D-galactose in a ratio of 1:4:1. The structure of the furostanol (I) has been established by methylation, enzymatic hydrolysis, and oxidative cleavage, and also by the oxidative cleavage of (II), as (25S)-5-furostan-2,3,6,22,26-pentaol 26-O--D-glucopyranoside 3-O-{[O--D-xylopyranosyl-(13)]-[O--D-glucopyranosyl-(12)-O--D-glucopyranosyl-(12)]-O--D-glucopyranosyl-(14)--D-galacto-pyranoside}.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 514–522, July–August, 1979.     

Zur Frage der Quantitativen Differentialthermoanalyse Cristobalithaltiger Staubproben

Zusammenfassung Mit einer DTA-Anlage eigener Entwicklung werden an Cristobalitproben verschiedener Herkunft und Entstehungsgeschichte Umwandlungstemperatur und Wärmetönung der --Inversion bestimmt. Die dabei gefundene Beziehung zwischen diesen beiden Größen ermöglicht unter gewissen Bedingungen die Ermittlung des Cristobalitgehaltes einer Staubprobe.

---

Temperature and heat of the --inversion in christobalite samples of various origin and way of production were measured with a self-constructed DTA-apparatus. A relationship was found between temperature and heat of reaction, which in certain circumstances enables to determine the christobalite content in dust samples.

---

Résumé Détermination, à l'aide d'une installation d'ATD personnelle, de la température et de la chaleur de transformation de l'inversion - de divers échantillons de cristobalite d'origine et de préparation différentes. Une relation est apparue entre ces deux grandeurs permettant de déterminer, sous certaines conditions, la teneur en cristobalite d'un échantillon de poussière.

---

– , . , .

     

Crystal Structure Study of the Metastable β-modification of Glycine and its Transformation into the α-modification

Crystal structure refinement was performed of the metastable modification of glycine (space gr. P2₁, a = 5.092(2) , b = 6.273(3) , c = 5.384(3), = 113.17(4)°, Z = 2, R = 0.0274). The crystals were obtained by a new method (not described in the literature): they were precipitated from a water solution with the addition of glacial acetic acid. The crystal structure of the glycine modification [space gr. P2₁/n, a =5.106(1) , b = 11.979(5) , c = 5.463(2) , = 111.75(2)°:, Z =4] was refined for comparison. Transition from the to the modification in a damp atmosphere was revealed, resulting in the formation of a strongly strained crystal of a mosaic structure. The orientation of the crystallographic axes in the newly formed crystal of the modification relative to the axes in the initial crystal of the modification was determined. It is shown that as in glycine, the lengths of the intramolecular C—O bonds in the modification are fairly similar [1.248(2) and 1.253(2) ] and the previously found significant difference between them is most likely due to the errors of the photomethod. A comparative analysis of the crystal structures of the and glycine modifications (glycine zwitterion packings and structure of intermolecular hydrogen bond networks) was performed. Data of the analysis are used to discuss the properties of the glycine modifications, the possible reasons for the stability of the modification in dry air, the difficulties of crystal growth from solutions, and the ease of crystallization of the modification under various conditions.     

Thermal analysis of mercury(I) sulfate and mercury(II) sulfate

The thermal decomposition of mercury(I) and (II) sulfates has been investigated by thermogravimetry. The solid-state decomposition products have been characterized by infrared and Raman spectroscopy, mass spectrometry and an X-ray diffraction method. It is concluded that mercury(I) sulfate decomposes in two steps, initially forming a mixture of metallic mercury and mercury(II) sulfate — the latter subsequently decomposes without forming a stable intermediate. The stoichiometry of disproportionation of mercury(I) sulfate and the thermal stability range of mercury(I) and mercury(II) sulfates have been established.

---

Zusammenfassung Die thermische Zersetzung von Quecksilber(I) und (II)-sulfaten wurde durch Thermogravimetrie untersucht. Die Festphasen-Zersetzungsprodukte wurden durch Infrarot- und Ramanspektroskopie, Massenspektrometrie und Röntgendiffraktion charakterisiert. Es wurde gefolgert, dass Quecksilber(I)sulfat in zwei Stufen zersetzt wird, unter anfänglicher Bildung eines Gemisches von metallischem Quecksilber und Quecksilber(II)-sulfat, welches in der Folge ohne Bildung eines stabilen Zwischenproduktes zersetzt wird. Die Stöchiometrie der Disproportionierung des Quecksilber(I)sulfats und der Bereich der Thermostabilität der Quecksilber(I) und Quecksilber(II)sulfate wurden ermittelt.

---

Résumé La décomposition thermique des sulfates de mercure(I) et de mercure(II) a été suivie par TG. On a caractérisé les produits de la décomposition en phase solide par spectroscopies infrarouge et Raman, spectrométrie de masse et diffraction des rayons X. On en a conclu que le sulfate de mercure(I) se décompose en deux étapes, formant initialement un mélange de mercure métallique et de sulfate de mercure(II), ce dernier se décomposant ensuite sans formation d'un intermédiaire stable. Les proportions stoechiométriques de la dismutation du sulfate de mercure(I) et de l'intervalle de stabilité thermique des sulfates de mercure(I) et de mercure(II) ont été établis.

---

- . , , . , , (), - . - .

     

Kinetics of propylene oxidation in the region of negative temperature coefficients of the rate

Kinetic regularities in the consumption of initial reactants and the accumulation of propylene oxidation products has been studied in the region of negative temperature coefficients of the maximum reaction rate (T=648–723 K). It has been revealed that for prolynene-enriched mixtures (C₃H₆:O₂=3:1) at P-20.66 kPa, the reaction rate is practically independent of the temperature, whereas for poor mixtures (C₃H₆:O₂=1:5) it decreases with increasing temperature.

---

a (T=648–723K). , (C₃H₆:O₂=3:1) P=20,66 , (C₃H₆:O₂=1:5) .

     

A rapid method of determination of specific surface areas

An apparatus and a method for the rapid determination of specific surface areas are described. The method is based on low temperature adsorption of nitrogen from the air and requires determination of the adsorbed gas at two relative pressures. The accuracy of the method, as compared with the BET technique, is ±9% for the adsorbents studied.

---

. . , BET, ±9% .

     

Determination calorimetrique des enthalpies de formation en metallurgie

The calorimetric methods used for the measurement of the enthalpy of formation of metallic systems are described and discussed. Special attention is paid to direct reaction calorimetry, dissolution calorimetry, precipitation calorimetry, combustion calorimetry... and non-reacting calorimetry is considered as an additional method from this point of view. Emphasis is placed on their particular field of application. Some recent developments are given.

---

Zusammenfassung Kalorimetrische Verfahren zut Messung der Bildungsenthalpie von metallischen Systemen wurden beschrieben und diskutiert. Besondere Aufmerksamkeit wurde dabei der Hinreaktionskalorimetrie, der Lösungskalorimetrie, der Fällungskalorimetrie, der Verbrennungskalorimetrie geschenkt, Nichtreaktionskalorimetrie wurde als eine zusätzliche Methode in dieser Hinsicht betrachtet. Das spezielle Anwendungsgebiet dieser Verfahren wird hervorgehoben und einige Neuentwicklungen gegeben.

---

, . , , , . . .

     

Thermodynamic aspects of conformational transitions in synthetic polypeptides

The helix-coil transition of organic solvent soluble homopolypeptides has been discussed from a largely thermodynamic view-point. The present state and the future prospects are considered.

---

Zusammenfassung Der Helix-Ungeordnete Übergang von in organischen Lösungsmitteln löslichen Homopolypeptiden wurde aus einem breiten Gesichtspunkt diskutiert, gegenwärtige Lage und zukünftige Entwicklungsaussichten erörtert.

---

R'esumé On a discuté d'une pointe de vue thermodynamique large la transition helix—non helix des homopolypeptides solubles dans des solvants organiques et considéré la situation actuelle ainsi que les perspectives futures.

---

, , . .

---

---

The present paper was supported by NSF Grant GB 33484.