Phase coexistence overlap induced by steric interactions

Novel phase diagram calculations, in which the two phase-separated regions of polymer stabilized colloidal suspensions overlap under certain constraints of the reduction in the range of the steric interaction with increasing temperature, are presented. A phase diagram displaying liquid-vapour, liquid-solid and vapour-solid coexistence with two triple points, but no critical points is shown to exist in qualitative agreement with observations.     

HPLC Determination of some antibilharzial antimonials by extraction of antimony

The antimonial drug (antimony potassium tartrate, antimony piperazine tartrate or antimony lithium thiomaleate) in aqueous solution or biological fluid is treated with sodium diethyldithiocarbamate in the presence of a suitable masking reagent, the pH is adjusted to 9 +/- 0.5. and the antimony complex extracted with n-hexane and determined by reversed-phase HPLC with an ODS column and detection at 254 nm. The limits of detection are 20 ng (for antimony potassium tartrate and antimony lithium thiomaleate) and 16 ng (for antimony piperazine tartrate).     

1-Alkoxyaziridines

The corresponding 1-alkoxyaziridines were synthesized by oxidation of methoxy-, ethoxy-, and isopropoxyamines with lead tetraacetate in the presence of 2-methyl-2-butene and 2,3-dimethyl-2-butene. The PMR spectra of the oxidation products were investigated, and the high pyramidal stability of nitrogen in these compounds was confirmed. The individual invertomers 1-alkoxy-2,2,3-trimethylaziridines were isolated by preparative gas-liquid chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1514–1519, November, 1972.The authors thank A. A. Potekhin, I. N. Somin, R. R. Kostikov, M. I. Komendantov, and M. A. Kuznetsov for their useful discussions.     

Hydration of acetylene on Cd2+ exchanged zeolites

The reaction takes place on Cd-containing Lewis sites, whereas the irreversible adsorption and condensation of product acetaldehyde on acidic OH groups of Cd-X, FAU catalyst results in deactivation. Preadsorbed ammonia moderates the deactivation, because it reacts with acetylene, and pyridine homologues are formed which block the accessible OH groups. Since in divalent cationic forms of clinoptilolite no OH groups are generated, Cd-clinoptilolite proved to be a catalyst of permanent activity.

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, Cd, — OH FAU, Cd-X. , .. , OH . OH, Cd- .

     

Use of long-chain alkylamines for preconcentration and determination of traces of molybdenum, tungsten and rhenium by atomic-absorption spectroscopy-II: molybdenum in soils, sediments and natural waters

Molybdenum is extracted as the thiocyanate complex with the quaternary long-chain aliphatic amine Aliquat 336 in chloroform, followed by evaporation of the solvent, dissolution in MIBK, and atomic-absorption spectroscopy. The method is simple, rapid and sensitive, with few interference problems for the determination of the Mo content of soils and sediments in the range 0.1-1.0 ppm with a relative standard deviation better than 5% when 1-g samples are used. Quantitative extraction from large volumes of aqueous solution has also been confirmed, allowing the determination of Mo in natural waters in the ppM range.     

Density matrix in the open shell theory

All the second-order density matrix spin components for the spin-projected Slater determinant are presented as expansions in direct products of powers of unprojected spin- and residual electron density matrices. Spin components of the second-order transition density matrices between spin-projected Slater determinants built of orthogonal orbitals are also obtained.     

Determination of mono-, di- and polyamines in foods using a single-column amino acid auto-analyzer

A fully automated, rapid and sensitive method was developed to analyze fourteen different biogenic amines in food. Using a Technicon C4 ion-exchange resin column (20 m X 0.5 cm), adapted to an automatic Technicon TSM amino acid analyzer, the following amines were separated and quantified: adrenaline, noradrenaline, 1,3-diaminopropane, putrescine, cadaverine, histamine, spermidine, dopamine, spermine, agmatine, tyramine, serotonin, phenethylamine and tryptamine. Five buffers were required to elute the amines using a gradient of pH from 5.6 to 12.7; the column temperature was maintained at 65 degrees C. The method was also assayed on ground beef, cheese and wine samples. Amines from cheese and ground beef samples were extracted with 0.6 M perchloric acid. No extraction of wine samples was necessary.     

Globin chain separation by SDS polyacrylamide gel electrophoresis. Simple screening method for elongated hemoglobin chains

A simple method for the separation of hemoglobin chains from hemolysate or globin, by sodium dodecyl sulfate polyacrylamide gel electrophoresis, is described. The alpha, beta, and gamma chains can be clearly separated from each other. The alpha chain has the highest mobility, the beta chain has a slower mobility than the gamma chain, while the delta chain has about the same mobility as the beta chain. Hemoglobins with elongated chains can easily be detected by this method. Tak-beta, elongated by 11 residues, moves much more slowly than betaA but is much faster than alpha Constant Spring which is elongated by 31 residues. Screening of several individuals with slow-moving hemoglobins using this method led to the finding of a case with Hb Tak-beta thalassemia and other carriers of Hb Tak.     

ENERGY TRANSFER AND PHOTOOXIDATION KINETICS IN REACTION CENTERS ON THE PICOSECOND TIME SCALE

Abstract— Picosecond 530 nm actinic and 1242 nm probe light pulses have been used to measure the kinetics of energy transfer and photooxidation in Rhodopseudomonas sphaeroides R-26 reaction centers. The energy transfer rate between bacteriopheophytin and the bacteriochlorophyll dimer is 1.0 ± 0.3 ± 10¹¹s^-land photooxidation of the dimer occurs within 5 ps after the dimer reaches the first excited singlet state. Using these parameters in a simple model we are able to explain the odd result that the number of reaction centers oxidized by a saturating 530 nm actinic picopulse is only 60% of the number oxidized by a saturating CW light source.     

Properties and analytical applications of the heteropolymolybdates of phosphorus, arsenic, silicon and germanium-IV Determination of phosphomolybdic and silicomolybdic acids via the molybdenum content, with phenylfluorone

Procedures are proposed for the determination of phosphorus and silicon in the ppM range, by extraction of phosphomolybdic and silicomolybdic acids with organic solvent, decomposition of the complex and spectrophotometric determination of its molybdenum content.