Adsorption Isotherm Accounting for the Electrode Elasticity: Special Solutions

The single-phase adsorption on a solid electrode out of a dilute solution is investigated. As a continuation of the previous paper, on the basis of the complete electrocapillarity equation, an adsorption isotherm equation is derived and supplemented by equations of compatibility of the physical quantities. The equations contain a new parameter, , which is a derivative of the dimensionless surface adsorbate concentration by the relative variation of the electrode surface area. Their solution is obtained in relation to the dimensionless charge density of the electrode surface q for the case of = (). As a result of employing a linear model for q by , the problem of determination of the unknown model functions is reduced to common differential equations that use the capacitance or estance curves as the boundary conditions. In the first case, we suggest to calculate the unknown integration parameter by the method of mathematical optimization, employing coulometric data.     

Radiometric measurements of fallout under accidental conditions

Empirical expression for experimentally obtained functional dependence between the results of total -activity and integral -activity activity of fallout, measured during May, 1986, at a control point: 44°47 northern latitude and 20°32 eastern longitude, has been established in order to enable estimation of the level of fallout contamination by -emitters when total -activity values are known.     

Circular dichroism spectra of the inclusion complexes of phlorizin in cyclodextrins

Two aromatic rings of a phlorizin molecule form inclusion complexes with -CD and -CD. Induced circular dichroism spectra of these complexes have been measured to estimate the orientation of the two aromatic rings in the hydrophobic space of CDs. Apparent complex formation constants have been also estimated for each complex. It is concluded that phlorizin forms a stronger inclusion complex with -CD than with -CD.     

Synthesis of mono- and dilactones from 2,7-disubstituted 4-octene-1,8-dioic acids

2,7-Disubstituted 4-octene-1,8-dioic acids are formed by heating the-lactones of 2,7-disubstituted 4-hydroxyoctane-1,8-dioic acids to 250°C. The bromination of these unsaturated dicarboxylic acids gives,-dilactones of 2,7-disubstituted 4,5-dihydroxyoctane-1,8-dioic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1590–1592, December, 1971.     

Reactions of 1-vinyl-4,5,6,7-tetrahydroindole and its mixtures with 4,5,6,7-tetrahydroindole in the presence of Cr- and Pd-coated catalysts

In the presence of Cr- and Pd-coated -alumina catalysts, 1-vinyl-4,5,6,7-tetrahydroindole (VTHI) and its mixtures with 4,5,6,7-tetrahydroindole (THI) are converted into 1-ethyl-4,5,6,7-tetrahydroindole (1-ETHI), indole, and 2-ethylindole, in proportions dependent on the reaction conditions and the catalyst. Over a sulfided 1% Pd--alumina catalyst in the presence of hydrogen at 200°C, VTHI is converted into 1-ETHI and THI. When the temperature is raised to 300–350°C, indole is formed in addition to these products. A 11 mixture of VTHI and THI over 1% Pd--alumina at 300°C gives indole and 2-ethylindole, over a sulfided 1% Pd --alumina catalyst at 200°C, 1-ETHI, and over a Cr oxide catalyst at 500°C, indole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1417–1422, June, 1991.     

Synthesis of γ-keto alcohols and dihydrofurans from 2-furanpropanols

Summary A method was developed for the preparation of-keto alcohols and hence 2,3-dihydrofurans by the catalytic hydrogenation of 2-furanpropanols over platinized charcoal at 220° with formation of acetic esters of-keto alcohols, from which as a result of methanolysis-keto alcohols and dialkyldihydrofurans are formed.     

Reaction of N-Acyl-γ-aminobutyric Acids with 3-Ethoxycarbonylbenzotriazole 1-Oxide

Reactions of ,-dehydrodipeptides containing a terminal -aminobutyric acid residue with 3-ethoxycarbonylbenzotriazole 1-oxide at 90-100°C result mainly in cleavage of the peptide bond. In the cold, the corresponding ethyl ester and N-acyl--butyrolactam are formed. Analogous reactions with N-benzoyl- and N-benzyloxycarbonyl--aminobutyric acids leads to formation of the corresponding ethyl esters.     

Condensation of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester and decarboxylation of the reaction products obtained

-(1-Ethoxyvinyl)- and -(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactones were obtained by the reaction of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester. Decarboxylation of the -(1-ethoxyvinyl)--ethoxycarbonyl-butyrolactones in DMSO leads to -(1-ethoxyvinyl)--butyrolactones, the hydrolysis of which gives -acetyl-butyrolactones. Ethyl trans-3-acetyl-3-pentenoate was obtained by decarboxylation of -methyl--(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactone in DMSO.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 22–25, January, 1992.     

The cyclodextrin-quinone inclusion compounds in an aqueous solution at 77. K. I. 9,10-anthraquinone sulfonates and 1,4-naphthoquinones

The complex formation between cyclodextrins (-, -, -CD's and dimethyl-\-CD) and quinones (three 9, 10-anthraquinone sulphonates and two 1,4-naphthoquinones) in the water-ethylene glycol 1:1 mixture solution at 77 K was investigated using the n^* phosphorescence spectra and their excitation spectra and lifetimes of the quinones. It was concluded on the basis of the experimental results that the complexes have various structures according to the CD-quinone combination used. Vitamin K₃ was found to form the photodimer very efficiently in the presence of -CD. The assumed CD:quinone ratios of the complexes are given.     

Fuel Combustion Reactions and Catalysts: XXI. Synthesis and Characterization of Modified Mn–Al–O Catalysts for High-Temperature Oxidation

The phase composition of supported Mn–Al–O catalysts and their activity in the reaction of methane oxidation were studied depending on the composition of aluminum oxide supports (-Al₂O₃ with different -Al₂O₃ contents modified with individual Mg, La, and Ce oxides or Mg + La and Mg + Ce oxide mixtures) and calcination temperatures (500, 900, and 1300°C). It was found that the Mn–Al–O catalysts based on -alumina containing -Al₂O₃ and modified with Mg, La, or Ce additives are more active and thermally stable (up to 1300°C) than the samples based on pure -Al₂O₃. A conclusion was drawn that a higher degree of disorder of the structure of -Al₂O₃, compared to that of -Al₂O₃, is favorable for a deeper interaction of manganese and modifying additives with the support at the early stages of the synthesis and for the formation of Mn–Al compounds with complex composition (solid solutions and/or hexaaluminates) at 1300°C. These compounds are responsible for the stability and high activity of the catalysts in methane oxidation.     

Sol-Gel Synthesis and Gas Adsorption Properties of CuCl Modified Mesoporous Alumina

Cuprous chloride (CuCl) modified unsupported -alumina membranes and adsorbent granules were synthesized by sol-gel processing followed by wet-impregnation of CuCl. The CuCl coated -alumina remains mesoporous with a uniform pore size distribution and a large surface area. The mesoporous alumina granules, prepared by a sol-gel oil-drop process, exhibit excellent mechanical strength and attrition resistance. The CuCl modified -alumina preferentially adsorbs ethylene and carbon monoxide, with a saturated adsorption capacity of 0.67 and 0.78 mmol/g, respectively. Both equilibrium capacity and kinetic rate for adsorption of ethylene and carbon monoxide on the CuCl modified -alumina are much larger than those for ethane and carbon dioxide. These results indicate the potential use of the sol-gel derived CuCl modified -alumina for separation of ethylene or carbon monoxide from its gas mixture containing ethane or carbon dioxide.     

The influence of crystallinity on the secondary glass transition in polycarbonate

Summary Dynamic mechanical properties of polydian carbonate were measured with a vibrating reed method for various degrees of crystallinity (up to ca. 20 %). The explored temperature region was from — 180 °C to 120 °C; the frequency was about 100 Hz. Crystallinity was measured by density and thermal measurements.In the region of the -relaxation in polydian carbonate crystallinity appears to have no influence on tg . The storage modulus increases somewhat with increasing crystallinity and consequently the loss compliance decreases in the region of the -relaxation.

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Zusammenfassung Dynamisch-mechanische Eigenschaften des Polykarbonats von BisphenolA, wurden mit Hilfe der vibrating-reed-Methode für verschiedene Kristallisationsgrade gemessen. Der Temperaturbereich war von — 180 °C bis 120°C; die Frequenz war etwa 100 Hz. Die Kristallinität wurde aus Messungen der Dichte und der Schmelzenthalpie bestimmt. Es zeigte sich im Gebiet der -Relaxation kein Einfluß der Kristallinität auf tg .Der Modul nimmt mit der Kristallinität etwas zu und dementsprechend nimmt die Verlustkomplianz im Gebiet der -Relaxation ab.

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With 6 figures and 2 tables     

Preparation and Characterization of Thin Optically Transparent Alumina and Ce-doped Alumina

Transparent and porous boehmite, -Al₂O₃ (500°C) and -Al₂O₃ (900° and 1000°C) thin sheets (50–100 m) have been prepared from boehmite sols. -Al₂O₃ shows about 48% porosity and 292 m²/g surface area. On transformation from -Al₂O₃ (500°C) to -Al₂O₃ (900°C), the porosity still remains high, i.e. 45%; however, the surface area becomes 138 m²/g. The porosity and surface area of -Al₂O₃ become about 41% and 97 m²/g respectively on further heating to 1000°C. A gradual increase of average pore radius during this thermal treatment suggests that coarsening of the pore occurred during the densification process. Both -Al₂O₃ and -Al₂O₃ show high degree of transmission from UV to NIR wavelength region. Cerium exists in +4 oxidation state in the boehmite as well as in the - and -Al₂O₃. The ultraviolet absorption edge of the alumina was tailored by varying the concentration of cerium.     

An empirical equation-of-state for solid-fluid interfacial free energies

The contact angle,, formed by a liquid on a solid surface in air depends on the solid-air ( _S ), liquid-air ( _L ) and solid-liquid ( _SL ) interfacial free energies, as described by Young's equation. Critical examination of reported contact angles for numerous liquids and solids leads to an empirical correlation between _sL and both _Y and _S . Combination of this correlation with Young's equation gives an empirical relation allowing calculation of _S from _L and Calculations made with these empirical relations agree well with estimations of _S obtained by the method of critical spreading, and are consistent with Young's equation.Founded and supported by F. Hoffmann-La Roche and Co., Limited Company, Basel, Switzerland.     

Cyclodextrine und synthetische Wirthohlräume — Vergleich der Komplexierungseigenschaften

It is shown that the synthetic host compounds described in this study possess higher complexation constants versus 1,8-ANS than -or -cyclodextrin. The attachment of side chains to -cyclodextrin increases the complex formation, whereas the value of -cyclodextrin is not reached. The quaternary ammonium nitrogens of the synthetic hosts may be replaced by amide groups without diminution of the association constants. Bicyclic compounds in general bind more strongly than monocyclic hosts due to tighter inclusion and increased hydrophobic interaction. The influence of side chains attached to synthetic host compounds on the complexation constants is difficult to predict.

     

The effects of ionizing radiation on the thermophysical properties of substituted Sr-ferrites

Different samples of Sr-ferrites have been synthesized by the usual ceramic and high temperature sintering technique. On these samples, several measurements have been undertaken namely, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), the temperature dependence of DC electric conductivity before and after -absorbed dose, and the temperature dependence of dielectric constant. Results obtained were explained, correlated, interpreted and discussed in detail on the basis of the interaction of temperature, dopant cations and -radiation with the Sr-ferrite lattice. The activation energy (E), energy gap for semiconduction and activation energy for -radiation-induced carrier liberation () were evaluated for the first time. Finally, a mechanism for semi-conductivity in terms of energy band picture in intrinsic ferrite semiconductors is suggested and discussed.     

Macromolecular conformations at the water-air interface: Interactions between alpha and beta conformations of polypeptides

Bidimensional miscibility between alpha and beta conformations of polypeptides was investigated at the water-air interface in the 15°–30°C temperature range. The polypeptides were poly--methyl-L-glutamate (PGMG), poly--benzyl-L-glutamate (PGBG) and poly--benzyl-L-aspartate (PBBA). The polypeptide conformations, alpha or beta, were checked by IR spectroscopy using the MIR technique.The spreading isotherms for mixed monolayers alpha-PGMG/alpha-PGBG and beta-PGMG/beta-PBBA showed bidimensional miscibility both for alpha-alpha and beta-beta mixtures.For the alpha-alpha system, attractive interactions among the polypeptide alphahelices were found (G_mix<0) and the driving factor appeared to be the entropic one (packing). Compressibility moduli and surface potential measurements showed a fluidification effect of alpha-PGBG on mixed monolayers. In the case of beta-beta mixed monolayers, ideal behaviour was observed and no fluidification effect detected.Scanning electron micrographs made on collapsed monolayers showed hexagonal structures for alpha-alpha mixtures and no well-defined or characterized features for the beta-beta system.     

Synthesen von kernsubstituierten N,N-Diphenyl-β-alaninen

Zusammenfassung N,N-Diphenyl--alanine mit Substituenten in einem oder in beiden Phenylresten wurden durch Umsetzung von entsprechenden Diphenylaminderivaten mit -Propiolacton erhalten. In ähnlicher Weise reagierte Diphenylamin mit -Butyrolacton zu -(N,N-Diphenylamino)-buttersäure. 4,4-Diäthyldiphenylamin und 2-Chlor-6-methyl-diphenylamin wurden als Ausgangsmaterialien für die entsprechenden -Alanine hergestellt.

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N.N-Diphenyl--alanines with substituents in one or in both of the phenyl groups were synthesized by reactions of the corresponding diphenylamine derivatives with -propiolactone. Similarly diphenylamine reacted with -butyrolactone to give -(N.N-diphenylamino)-butyric acid. 4.4-Diethyldiphenylamine and 2-chloro-6-methyldiphenylamine were prepared as starting materials for the corresponding -alanines.

     

Dielectric constants of acetonitrile, γ-butyrolactone,propylene carbonate,and 1,2-dimethoxyethane as a function of pressure and temperature

The dielectric constants of 1,2-dimethoxyethane, acetonitrile, -butyrolactone, and propylene carbonate were determined from capacitance measurements extrapolated to infinite frequency; ln are reported as a function of pressure up to 80 MPa at 15, 25, 35, 45°C and as a function of temperature in the range 10 to 50°C at 0.10133 MPa. The variation of ln with temperature or pressure can be expressed by a second order polynomial expression. The isothermal compressibilities of the solvents were determined at 25°C from sound velocities, densities, and heat capacities. A simple correlation can be established between ln /P and for most aprotic solvent.     

Effect of cascade coincidences on the efficiency calibration of a gamma-X detector

The sensitivity on n-type gamma-X detectors for low-energy X- and -rays calls for coincidence corrections in the efficiency calibration that do not apply to the calibration of p-type detectors. Corrections were calculated for the effect of cascade coincidences between -rays, X-rays, annihilation radiation, and bremsstrahlung, for 15 radionuclides frequently used for efficiency calibration. Experimental results are presented for a -X detector with 37% relative efficiency at distances from 0.9 to 17.5 cm. After coincidence correction smooth efficiency curves were found for the energy range 12 to 2750 keV, even for the position closest to the detector.