The influence of basic calcium chloride nuclei on the hydration of calcium chloridesilicate

The influence of CaCl₂ · Ca(OH)₂ · H₂O nuclei on the hydration of Ca₃SiO₄Cl₂ was studied by means of calorimetry, X-ray diffraction, simultaneous DTA-TG and chemical analysis of the liquid phase.

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Zusammenfassung Der Einfluss von CaCl₂ · Ca(OH)₂ · H₂O-Zusätzen auf die Hydratation von Calciumchlorid-silicat Ca₃SiO₄Cl₂ wurde durch Kalorimetrie, Röntgenbeugung, simultane TG-DTA und chemische Analyse der flüssigen Phase untersucht.

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l₃ · ()₂ Ca₃SiO₄Cl₂ , .

     

Kinetic model of catalytic ethylene oxidation

The kinetics of ethylene oxidation on a pumice supported silver catalyst promoted with chlorine has been studied. A simplified kinetic equation with two parameters is given to describe the process over a wide range of ethylene concentrations. The parameters of the equation have been determined as a function of the temperature.

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, - . -, . .

     

Degradation of rocket insulator at high temperature

The degradation of a rocket insulator compound based on ethylene propylene diene rubber (EPDM) containing asbestor, cork and iron oxide (Fe₂O₃) as fillers has been studied at high temperature (up to 600°) by using differential thermal analysis (DTA) and thermogravimetry (TG). The changes in physical properties on high-temperature aging are also reported. EPDM gum vulcanizates involving different types of diene, namely ethylidene norbornene (ENB), dicyclopentadiene (DCPD) and 1,4-hexadiene (HD), were used. In each case, the kinetic parameters for degradation have been evaluated. From these data, the lifetime of the rocket insulator compound has been found.

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Zusammenfassung Die Zersetzung einer Raketenisolator-Verbindung auf Äthylen-Propylen-Dien-Gummibasis (EPDM) mit Asbest, Kork und Eisenoxid (Fe₂O₃) als Füllstoffe wurden bei hohen Temperaturen (bis 600°) mittels Differentialthermalanalyse (DTA) und Thermogravimetrie (TG) untersucht. Die bei Hochtemperaturen eintretenden Veränderungen der physikalischen Eigenschaften sind ebenfalls angegeben. Verschiedene Typen von Dienen, nämlich Äthyliden-norbornen (ENB), Dicyclopentadien (DCPD) und 1,4-Hexadien (HD) enthaltenden EPDM-Gummivulkanisate waren Gegenstand der Untersuchung. In allen Fällen wurden die kinetischen Parameter der Zersetzung ermittelt. Aus diesen Daten wurde die Lebensdauer der Raketenisolator-Verbindung bestimmt.

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600° (), , . , . , , 1,4- . . .

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The authors are grateful to the Indian Space Research Organization for funding, and acknowledge the help and suggestions from Mr. T. S. Ram and Mr. Baby John, R.P.P., V.S.S.C., Trivandrum. The authors are also grateful to Prof. S. K. De, Rubber Technology Centre, and Prof. R. Ghosh, Chemistry Department, I.I.T., Kharagpur.

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The authors thank Mr. Asutosh Ghosh, Indian Association for the Cultivation of Science, for experimental assistance.     

Interaction of Hydroxy Acids with β-Cyclodextrin

The solubility of -cyclodextrin (-CD) was studied in aqueous solutions of various organic acids. The hydroxy acids, especially citric and tartaric acid were found to increase the solubility of -CD, while some other carboxylic acids reduced it. From solubility data the apparent complex association constants were calculated.     

Solvate shell rearrangements and solvation corrections to the Br?nsted equation

Solvate corrections f^solv for the Brönsted equation have been estimated under the assumption of the minimum work of shell rearrangement (MWSR).

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f^solv ().

     

A comparative study of uncatalyzed and catalyzed oscillatory behavior of different mono-and dihydroxybenzoic acids in acidic bromate

Optimum and boundary conditions for uncatalyzed and catalyzed temporal oscillations in the redox potentials in the oxidation of mono- and dihydroxybenzoic acids in acidic bromate (H₂SO₄) have been established and compared. The number and relative positions of the functional groups, in the aromatic ring have been found to influence the oscillatory behavior. Ferroin has been found to enhance the oscillatory behavior considerably as compared to Ce(IV) and Mn(II). A probable explanation of the oscillatory behaviour of these system is suggested.

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- - (H₂SO₄). . , Ce(IV) Mn(II), . .

     

Determination of Methacycline and Glucose in Biological Fluids by Europium(III)-Sensitized Luminescence

Complexation in the Eu(III)–methacycline and Eu(III)–methacycline–hydrogen peroxide systems was studied by luminescence. It was proposed to use the studied complexes as analytical forms for the luminescence determination of methacycline in blood plasma (lower determination limit 2.5 g/mL) and urine (25 g/mL) and for the indirect determination of 0.025–0.7 mM glucose in blood plasma.     

Stereochemistry of heterocyclic compounds

Summary On the basis of a number of chemical reactions, views are expressed on the possible steric structure of 1, 2, 5-trimethyl-4-ethyl-4-piperidinol isomers (I,, ), the corresponding acetylenic alcohols (II, ,), and certain piperidine derivatives obtained from them.     

Separation of gonadal steroid epimers using high performance liquid chromatography

Summary Chromatographic separation of biologically active epimeric steroids was carried out using a combination of normal and reversed phases. Testosterone (17-OH) was separated from its 17-OH epimer epitestosterone using a normal phase silica column whereas their reduced 5-metabolites were separated on a reversed phase system. The separation of other gonadal steroids including the epimers 20- and 20-hydroxypregn-4-en-3-one is also discussed. The technique is particularly useful for separating mixtures of naturally occurring steroid epimers prior to radioimmunoassay.     

Physico-chemical structure of oxycellulose after one-month and one-year storing,determined by the derivatograph

The effects of ageing for periods of one month and one year upon chemically preoxidized and radiation-sterilized oxycellulose were investigated. Changes in chemical structure and energetic excitation of atomic groups of the oxycellulose skeleton were evaluated from qualitative and quantitative aspects. Use was made of numerical interpretation of activation energy quantities, weight losses, the quantitative energetic quantity EW, and thermal effects (areas of DTA curve peaks) of individual degradation reactions, when applying the oxidation pyrolysis method with a Derivatograph.

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Zusammenfassung Die Wirkung der Alterung von einem Monat bzw. einem Jahr auf chemisch präoxidierte und durch Bestrahlung sterilisierte Oxycellulose wurde untersucht. Änderungen in der chemischen Struktur und der energetischen Aktivierung der Atomgruppen des Oxycellulose-Skeletts wurden qualitativ und quantitativ bewertet. Die numerische Interpretation der Aktivierungsenergien, die Gewichtsverluste, die quantitativen Energiemengen EW und die Werte des thermischen Effekts (die Fläche der DTA-Peaks) der einzelnen Abbaureaktionen wurden unter Einsatz der Oxidations-Pyrolysenmethode mit dem Derivatographen bestimmt.

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Résumé On a étudié l'effet d'un vieillissement d'un mois et d'une année sur l'oxy-cellulose préoxydée par voie chimique et stérilisée par irradiation. On a évalué d'un point de vue qualitatif et quantitatif les changements de la structure chimique et de l'excitation énergétique des groupes d'atomes du squelette de l'oxycellulose. En suivant la pyrolyse à l'aide d'un Derivatograph on a établi l'interprétation numérique des valeurs respectives de l'énergie d'activation, des pertes de poids, des quantités d'énergie EW et de l'effet thermique (surface des pics sur les courbes ATD) pour les réactions individuelles de dégradation.

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. . , , EW ( ) .

     

Crazes in amorphous polymers I. Variety of the structure of crazes and classification of different types of crazes

In investigating 0.5- to 5 m-thick deformed samples in a 1000 kV high-voltage electron microscope, the formation and structure of crazes were studied in different amorphous polymers (PS, SAN, PVC, and the highly radiation-sensitive polymers PMMA and PC). Different craze types were found and classified. There are some types of true crazes with a fibrillar structure or rather a homogeneous structure, which have to be distinguished from only craze-like deformation zones. A peculiarity was found in PMMA which produces a craze type different in structure from the well-known fibrillated crazes typical of PS.     

Kinetics and mechanism of oxidation of sulfasomidine by peroxydisulfate ion

Results of the kinetic studies of peroxydisulfate ion oxidation of sulfasomidine (N-(2,6-dimethyl-4-pyrimidyl)-4-aminobenzenesulfonamide) in aqueous medium are discussed. N,N-bis(2,6-dimethyl-4-pyrimidyl)azoxybenzene-p,p-disulfonamide has been identified as the main oxidation product. On the basis of product identification and kinetic studies a radical mechanism has been proposed.

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(N-(2,6--4-)-4--) . N,N-(2,6--4-)--,-. .

     

Can TMS and DSS be used as NMR references for cyclodextrin species in aqueous solution?

Tetramethylsilane (TMS) can be included by -cyclodextrin (-CD), and sodium 2,2-dimethylsilapentane-5-sulphonate (DSS) can form inclusion complexes with - and -CD. The NMR chemical shifts are changed considerably as a result of the strong interaction between CD and the guest compound in the inclusion complexes. A downfield shift of as much as 0.63 ppm shift downfield has been observed for the protons of external TMS in CD aqueous solution. In view of this, the question arises of whether TMS and DSS can be used as internal references. DSS in D₂O is suggested as an external reference for aqueous cyclodextrin solution in NMR measurements.     

The relation between the molecular weight and intrinsic viscosity of polymethyl acrylate

Summary A series of unfractionated and fractionated samples of polymethyl acrylate of different low molecular weights have been prepared by homogeneous solution. polymerization in dimethyl formamide in presence of , '-azo-(-cyano-n-valeric acid) as initiator under a variety of conditions. The number-average molecular weights have been determined by end-group titrations and vapour pressure osmometry. The following []-M relationships for polymethyl acrylate have been obtained.[] = 33.5 x 10^–5M^0.63 for unfractionated samples in benzene at 25 °C. [] = 3.89 x 10^–5M^0.843 for fractionated samples in benzene at 35 °C.With 2 tables     

Nitroderivate vonβ,β,β-Trihalo-α,α-bis-(4-alkoxybzw. 4-oxy-phenyl)-äthanen

Zusammenfassung Auf Grund von Modellbetrachtungen wurde die Existenz der in der Literatur beschriebenenOctanitro-Derivate von ,,-Trihalo-,-bis-(4-alkoxy-phenyl)-äthanen in Zweifel gezogen. Entsprechende Untersuchungen ergaben, daß es sich bei ihnen umTetranitro-Verbindungen handelt und daß es nicht möglich ist, diese DDT-Analogen mehr als vierfach zu nitrieren. Die Konstitution der Tetranitro-Verbindungen wurde durch Abbau bewiesen: Beim ,,-Trichlor-,-bis-(3,5-dinitro-4-methoxy-phenyl)-äthan (II) durch Überführung in das entsprechende Keton (VII), beim ,,-Trichlor-,-bis-(3,5-dinitro-4-äthoxy-phenyl)-äthan (IV) durch Entalkylierung und Methylierung zu II. Der Beweis der 3,3, 5,5-Stellung der Nitrogruppen in II und IV ist auch für andere Tetranitro-Derivate von ,,-Trihalo-,-bis-(4-X-phenyl)-äthanen (X=Substituenten I. Ordnung) von Bedeutung.Mitt. II der Reihe: Stereochemische Untersuchungen in der Diphenylmethanreihe.     

Infrared Luminescence of Neodymium in Complexes with Macrocyclic Schiff Bases

The 4f-luminescence of neodymium in complexes with macrocyclic Schiff bases was studied. Relation between the type of the macrocyclic ligand and the luminescence efficiency was examined. The luminescence intensity depends on the number of chromophoric aromatic fragments in the ligand, that act as photoantennas, i.e. as accumulators of excitation energy.     

Flame atomic-absorption spectrometric determination of traces of copper, iron, lead and manganese in nitric acid by injection dosation of concentrated solutions neutralized with ammonia

Summary The dosation system MS-11T working in the solvent-sample-solvent mode was used for the flame atomic-absorption spectrometric determination of copper, lead, iron and manganese in concentrated nitric acid. The acid was neutralized with gaseous ammonia. The resulting concentrated solution of ammonium nitrate (corresponding to 46.4% HNO₃) was thermostatted at 75°C and 250 l-portions were injected into the flame. The effect of the temperature of sample and washing solvent was studied. The precision of the analysis was improved by ensemble summation of the signals. The trace element concentrations, determined by the method of standard addition, were at 0.1 mg/l level.Dedicated to Prof. Dr. Ing. Bernhard Schrader on the occasion of his 60th birthday     

Ideal Conductivity Profile of a Porous Matrix for a Flow-through Porous Electrode with a High Conversion Degree of the Electroactive Component

The possibility of designing an equally accessible, in electric respect ( const), porous electrode (PE) is considered. The design involves creating a special conductivity profile of the solid phase, _s(x), in conditions of considerable variations of current density inside the electrode. A generalized expression for an ideal profile _s(x) at any current distribution is derived, and some concrete solutions for different PE operation modes at the limiting current of the target reaction are obtained. The profiles are exponential over a major fraction of PE and change to hyperbolic at a low conversion degree of the electroactive component. Similarities and differences of the profiles are analyzed. At a high conversion degree, only the exponential profile ensures effective operation of the entire surface of PE and selectivity of the target reaction.     

Retention Time Locking in the Determination of Narcotic Drugs by Chromatography and Chromatography–Mass Spectrometry

The use of retention time locking (RTL) in the development of unified procedures for the detection and quantitative determination of drugs in biological fluids was considered. With consideration for the use of RTL, a chromatographic procedure with flame-ionization and mass-selective detection was developed for the detection and quantitative determination of opiates and their synthetic analogs; phenylalkylamine derivatives; cocaine; ketamine; and other narcotic drugs, their derivatives, and metabolites in urine. The analytical ranges for chromatography–mass spectrometry were 0.05–1000 and 0.005–1000 g/mL under the conditions of total ion current (TIC) scanning and selected ion monitoring (SIM), respectively. With flame-ionization detection (GC–FID), the analytical range was 0.5–1000 g/mL.