Oscillations of Short Periods in Neutron and Strange Stars

We present a model of a remnant of supernova, and we analyze the correlation with the observational data to short periods oscillations between a neutron star and a strange matter star. The results confirm previous conclusions.     

Analysis of individual natural pyrethrins in indoor matrices by HRGC/ECD

An HRGC/ECD method is presented which permits the identification and quantitation of individual components of pyrethrins (cinerin I, jasmolin I, pyrethrin I, cinerin II, jasmolin II, pyrethrin II) in indoor matrices (airborne particles, house dust) after application of an agent containing pyrethrum. In order to prepare calibration standards for the individual components of the pyrethrum extract, the pyrethrins were isolated hy semi-preparative HPLC and their content and purity were determined by ¹H-NMR spectroscopy.     

THE MECHANISM OF THE 9,10-DIBROMOANTHRACENE MEDIATED TRIPLET-SINGLET ENERGY TRANSFER IN THE TETRAMETHYL-1,2-DIOXETANE ENERGIZED RUBRENE LUMINESCENCE*

Abstract— The ternary chemiluminescent system consisting of tetramethyl-dioxetane (TMD), 9 ,10-dibromoanthracene (DBA) and rubrene (Ru) has been investigated in benzene solution and in polystyrene matrices. DBA has been found to mediate the energy transfer between excited triplet acetone (³K), generated from TMD, and rubrene resulting in the enhancement of the Ru emission and reduction in the DBA emission. A detailed kinetic analysis confirms that ca. 50% of the enhanced chemilumines-cence involves triplet-singlet (TS) energy transfer from ³K to DBA, followed by singlet-singlet (SS) energy transfer from DBA to Ru, the remainder ca. 50% being due to reabsorption of DBA fluorescence by rubrene. It is concluded that the TS energy transfer is of the resonance type, occurring with a rate of k^TS_K.DBA= (1.4 ± 0.4) ± 10⁹M^-1s^-1 and an efficiency of ø^TS_K.DBA= 0.3 ± 0.1. As expected, the SS energy transfer is also of the resonance type, taking place at comparable rates in benzene solution and in polystyrene matrices, is. k^SS_DBARU= 1.5 ± 10¹⁰ M^-1 and (2.2 ± 0.2) ± 10¹⁰M^-1s^-1, respectively.     

Conformations of laulimalide in DMSO-d6

Laulimalide is one of the newest naturally occurring macrolides known to act as a microtubule stabilizing agent with properties similar to Taxol. It also stands as being one of the most flexible with 18 rotatable bonds. This large number of rotatable bonds allows for approximately 3(18) potential conformers. To examine the conformational energy surface of laulimalide, we have performed an NAMFIS deconvolution analysis for laulimalide in DMSO-d6. The latter has been supplemented with a post-NAMFIS energy analysis at the Becke3LYP/6-31G level that examines the opposing effects of internal hydrogen bonding and syn-pentane interactions. In this way, we have identified 15 laulimalide conformations that can be classified into 5 different families: Supine, Convex, Cobra, Stretch, and Concave motifs.     

Mikrogravimetrische Trennung von Zink und Uran

Zusammenfassung Im Zusammenhange mit der Bestimmung des Gehaltes schwach radioaktiver Mineralien an Blei, Thorium und Uran, dessen Ermittlung zur geologischen Zeitmessung nach der sog. Bleimethode erforderlich ist, wurde eine Trennung von Zink und Uran ausgearbeitet. Beide Elemente kommen in diesen Mineralien im Betrage von meist nur wenigen Hundertstelprozenten vor.Die Trennung wird in der Weise ausgeführt, daß das Zink nach dem Vorbild der makroanalytischen Arbeitsvorschrift vonC. Mayr in mit Monochloressigsäure und Natriumacetat gepufferter Lösung als Zinksulfid abgeschieden und nach Auflösen des Niederschlages in Salzsäure als Zinkammoniumphosphat bestimmt wird. Das uranhaltige Filtrat des Zinksulfids wird eingedampft und der Rückstand mit Salzsäure und Bromwasser abgeraucht, worauf man in essigsaurer ammonacetathaltiger Lösung das Uran in bekannter Weise als Uranyloxychinolat bestimmt.

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Summary In connection with the determination of the lead, thorium and uranium content of feebly radioactive minerals, a knowledge of which is necessary for the measurement of geological time by the so-called lead method, a separation of zinc from uranium has been worked out. Both these elements only occur to the extent of a few hundredths of one per cent in the minerals in question. The separation is carried out by precipitating the zinc according toC Mayr's macro procedure as zinc sulphide in a solution buffered with monochloracetic acid and sodium acetate; the precipitate is redissolved in hydrochloric acid, and the zinc determined as zinc ammonium phosphate. The filtrate containing the uranium is evaporated, and treated with hydrochloric acid and bromine water. The uranium is then determined by precipitation in the usual way with 8-hydroxyquinoline in acetic acid solution containing some ammonium acetate.

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Résumé Il a été établi une séparation du zinc et de l'uranium en connexion avec la détermination de la teneur en plomb, thorium et uranium de minéraux faiblement radio-actifs dont la mise au point était nécessaire à la détermination de l'âge géologique, d'après la méthode appelée Méthode au Plomb. Ces deux éléments se trouvent dans ces minéraux dans un rapport ne dépassant pas, pour la plupart du temps, quelques centièmes %.La séparation est conduite de telle manière que le zinc soit précipité sous forme de sulfure de zinc dans une solution tamponnée par de l'acide monochloracétique et le l'acétate de soude en se basant sur le mode de travail macroanalytique deC. Mayr. Après dissolution du précipité dans l'acide chlorhydrique, on détermine le zinc comme phosphate zinco-ammonique. Le filtrat contenant l'uranium est concentré et le résidu est évaporé à sec avec de l'acide chlorhydrique et de l'eau de Brome. Ensuite, on détermine l'uranium de la manière bien connue comme oxyquinoléate d'uranyle en solution acétique contenant de l'acétate d'ammonium.

     

Stannometry volumetric determination of iron(iii), vanadate,dichromate, iodate,bromate, ferricyanide ions and iodine

A generally applicable reductive method was elaborated by means of which numerous substances can be determined having oxidation potentials exceeding 0.3 V. The 0.1 N stannous chloride standard solution can be stored for some months, with a very slight decrease in titre, by using an automatic equipment for the supplying with carbon dioxide of the storage flask and burette. The procedure has so far been employed for the determination of ferric-, ferrous-, dichromate-, vanadate-, bromate-, iodate- and ferricyanide ions, furthermore of iodine. The advantage of the method is — in addition to the simplicity of the realization — that in the given ranges the experimental error never exceeds 0.5%, remaining usually under this limit.     

Basis set and electron correlation effects on the polarizability and second hyperpolarizability of model open-shell pi-conjugated systems

The basis set and electron correlation effects on the static polarizability (alpha) and second hyperpolarizability (gamma) are investigated ab initio for two model open-shell pi-conjugated systems, the C(5)H(7) radical and the C(6)H(8) radical cation in their doublet state. Basis set investigations evidence that the linear and nonlinear responses of the radical cation necessitate the use of a less extended basis set than its neutral analog. Indeed, double-zeta-type basis sets supplemented by a set of d polarization functions but no diffuse functions already provide accurate (hyper)polarizabilities for C(6)H(8) whereas diffuse functions are compulsory for C(5)H(7), in particular, p diffuse functions. In addition to the 6-31G(*)+pd basis set, basis sets resulting from removing not necessary diffuse functions from the augmented correlation consistent polarized valence double zeta basis set have been shown to provide (hyper)polarizability values of similar quality as more extended basis sets such as augmented correlation consistent polarized valence triple zeta and doubly augmented correlation consistent polarized valence double zeta. Using the selected atomic basis sets, the (hyper)polarizabilities of these two model compounds are calculated at different levels of approximation in order to assess the impact of including electron correlation. As a function of the method of calculation antiparallel and parallel variations have been demonstrated for alpha and gamma of the two model compounds, respectively. For the polarizability, the unrestricted Hartree-Fock and unrestricted second-order M?ller-Plesset methods bracket the reference value obtained at the unrestricted coupled cluster singles and doubles with a perturbative inclusion of the triples level whereas the projected unrestricted second-order M?ller-Plesset results are in much closer agreement with the unrestricted coupled cluster singles and doubles with a perturbative inclusion of the triples values than the projected unrestricted Hartree-Fock results. Moreover, the differences between the restricted open-shell Hartree-Fock and restricted open-shell second-order M?ller-Plesset methods are small. In what concerns the second hyperpolarizability, the unrestricted Hartree-Fock and unrestricted second-order M?ller-Plesset values remain of similar quality while using spin-projected schemes fails for the charged system but performs nicely for the neutral one. The restricted open-shell schemes, and especially the restricted open-shell second-order M?ller-Plesset method, provide for both compounds gamma values close to the results obtained at the unrestricted coupled cluster level including singles and doubles with a perturbative inclusion of the triples. Thus, to obtain well-converged alpha and gamma values at low-order electron correlation levels, the removal of spin contamination is a necessary but not a sufficient condition. Density-functional theory calculations of alpha and gamma have also been carried out using several exchange-correlation functionals. Those employing hybrid exchange-correlation functionals have been shown to reproduce fairly well the reference coupled cluster polarizability and second hyperpolarizability values. In addition, inclusion of Hartree-Fock exchange is of major importance for determining accurate polarizability whereas for the second hyperpolarizability the gradient corrections are large.     

Fortlanfende Literaturübersicht über Arbeiten mikrochemischen Inhaltes

Ohne ZusammenfassungUmfaßt die Literatur des Zeitraumes vom 5. Mai bis 20. Juni 1939.