Processing of neutron activation analysis data using a general purpose PDP-11 minicomputer

A minicomputer system is described for the off-line reduction of gamma spectral data from neutron activation analysis. The hardware and software systems are described. Both data printouts and spectral plots are produced. The versatility of system permits the availability of computer capability for both on- and off-line functions in a variety of analytical techniques at a moderate cost and under the control of the experimenter.     

Crystal chemistry of lithium in octahedrally coordinated structures. I. Synthesis of Ba8(Me6Li2)O24 (Me = Nb or Ta) and Ba10(W6Li4)O30. II. The tetragonal bronze phase in the system BaONb2O5Li2O

The preparation, single crystal growth, and crystallographic properties of a close-packed, eight-layer, hexagonal (a = 5.803 Å, c = 19.076 Å) modification having the stoichiometry Ba₈Nb₆Li₂O₂₄ and of a close-packed, ten-layer, hexagonal (a = 5.760 Å, c = 23.742 Å) phase with Ba₁₀W₆Li₄O₃₀ stoichiometry are discussed. The isostructural Ba₈Ta₆Li₄O₂₄ form of the eight-layer phase was also prepared (a = 5.802 Å, c = 19.085 Å). Proposed crystal structures involve the pairing of lithium and metal (Nb, Ta, or W) octahedra to yield face-sharing units. The relationship of this phenomenon to other known close-packed phases containing Li is demonstrated. An investigation of the Ba₈Nb₆Li₂O₂₄Ba₁₀W₆Li₄O₃₀ system is reported.A tetragonal bronze phase homogeneity region was delimited at 1200°C in the BaONb₂O₅Li₂O system. A new orthorhombic phase (a = 10.197 Å, b = 14.882 Å, c = 7.942 Å) was prepared with the stoichiometry Ba₄Li₂Nb₁₀O₃₀.     

Synthesis of [n]- and [n.n]cyclophanes by using Suzuki-Miyaura coupling

Reaction of the bis-9-BBN adduct of several dienes with 1,3-dibromobenzene via Suzuki coupling leads to a series of [n]metacyclophanes ranging in size from 10 to 17 atom members. In each case, two carbon-carbon bonds are formed in one reaction vessel. However, when the bis-9-BBN adduct of 1,5-hexadiene is coupled with a variety of aryl dihalides, larger [n.n]cyclophanes were formed in preference to the [n]cyclophanes. Four carbon-carbon bonds are formed in this instance. Single-crystal X-ray analyses of these [n.n]cyclophanes reveal interestingly shaped molecules with large cavities.     

High resolution TDL spectroscopy of the Ar-CH4 complex

The spectrum of the weakly bound complex Ar-CH4 in the 7 microm region was discovered, analysed, and compared with a spectrum, predicted from ab initio calculations. The measurements were made by probing a supersonic gas expansion with a tunable diode laser (TDL). Several bands of Ar-CH4 associated with different ro-vibrational transitions of the v4 vibration of CH4 were recorded and analysed in a spectral region from 1295 to 1330 cm(-1). In particular the following transitions were studied: j = 1 <-- 0 (at 1311 cm(-1)) reported in Pak et al. [Z. Naturforsch. 53 (1998) 725], j = 0 <-- 1 (at 1301 cm(-1)), j = 2 <-- 1 (at 1316 cm(-1)), and j = 3 <-- 2 transitions (at 1322 cm(-1)). Here, j denotes the angular momentum of the methane unit inside the complex. Analysis of the recently recorded j = 1 <-- 1 transitions at about 1306 cm(-1) in the region of methane Q(1) is in progress. The experimental results are compared with ab initio calculations. The close agreement between observed and ab initio spectra is convincingly demonstrated with respect to the gross spectral features, including many details of the spectra.     

Determination of k0- and Q0-factors of short-lived nuclides

k₀- and Q₀-factors of 18 short-lived nuclides used in reactor neutron activation analysis were determined using the Fast Irradiation and Measurement System (FIMS) of the TRIGA MARK II reactor at the Atominstitut der Österreichischen Universitäten. The Q₀-factors were either critically selected from literature, or experimentally determined according to theCd-ratio method, while the k₀-factors were additionally determined by theBare monitor method. A comparison is made with the values calculated by introduction of literature data for the input parameters. Moreover, a user oriented tabulation is presented of k₀-, Q₀-factors and related nuclear data. All results were critically tested with respect to their accuracy and precision.     

Papierscheiben-Säulenchromatographie

Zusammenfassung Durch Säulen aus Filtrierkarton kann in aufsteigender Chromatographie eine Substanz von störenden Begleitstoffen befreit werden. Es ist möglich, während des Betriebes durch Sprühreagenzien Feststellungen über die Lage des Stoffes in der Säule zu machen oder — bei kurzer Unterbrechung — mit einzelnen Scheiben Reinheitsprüfungen durchzuführen. Die Säule kann während des Betriebes verlängert werden. Eine quantitative chromatographische Bestimmung ist möglich.

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Summary A substance can be freed of interfering accompanying materials by ascending chromatographing in columns made of filtering paperboard. It is possible, during the operation, to locate the materials in the column by sprayed-on reagents or—with brief interruption—to conduct purity tests with individual disks. The column can be lengthened during the operation. It is possible to make a quantitative chromatographic determination.

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Résumé Il est possible de purifier une substance de produits gênants l'accompagnant par chromatographic ascendante sur des colonnes en carton filtre. Il est possible de se rendre compte de la position de la substance pendant l'opération à l'aide de réactifs pulvérisés et également après une courte interruption d'effectuer des essais de pureté sur des disques isolés. Pendant l'opération, il est possible d'allonger la colonne. Il est également possible d'effectuer une détermination chromatographique quantitative.

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Karlsruhe, Richard-Wagner-Straße 8.     

Geometric determinants of directional cell motility revealed using microcontact printing

Mammalian cells redirect their movement in response to changes in the physical properties of their extracellular matrix (ECM) adhesive scaffolds, including changes in available substrate area, shape, or flexibility. Yet, little is known about the cell's ability to discriminate between different types of spatial signals. Here we utilize a soft-lithography-based, microcontact printing technology in combination with automated computerized image analysis to explore the relationship between ECM geometry and directional motility. When fibroblast cells were cultured on fibronectin-coated adhesive islands with the same area (900 micrometers2) but different geometric forms (square, triangle, pentagon, hexagon, trapezoid, various parallelograms) and aspect ratios, cells preferentially extended new lamellipodia from their corners. In addition, by imposing these simple geometric constraints through ECM, cells were directed to deposit new fibronectin fibrils in these same corner regions. These data indicate that mammalian cells can sense edges within ECM patterns that exhibit a wide range of angularity and that they use these spatial cues to guide where they will deposit ECM and extend new motile processes during the process of directional migration.     

2D correlation analysis of the continuum in single molecule surface enhanced Raman spectroscopy

The role and the nature of the continuum in Surface Enhanced Raman Spectroscopy (SERS) are unclear. Here, two-dimensional (2D) covariance and correlation analysis is applied to single molecule SERS spectra on silver colloids with and without rhodamine 6G (native colloid). The resulting 2D covariance and correlation maps show that the sharp molecular Raman peaks from rhodamine 6G and the molecule responsible for the SERS peaks from the native colloid are correlated to different continua even though both continua are present in each data set. This suggests that two distinct active sites on the silver colloids produce the two different continua, and that each site has some molecular specificity.     

Manganese(II) chemistry of a new N3O-donor chelate ligand: synthesis, X-ray structures, and magnetic properties of solvent- and oxalate-bound complexes

The synthesis and characterization of a new N3O donor ligand N-benzyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine (bpppa) is reported. Treatment of bpppa with Mn(II)(ClO4)2.6H2O in acetonitrile solution yielded the mononuclear [(bpppa)Mn(CH3CN)(H2O)](ClO4)2 (1) which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and a solution magnetic moment measurement. Admixture of equimolar equivalents of bpppa and Mn(II)(ClO4)2.6H2O in methanol solution, followed by addition of 0.5 or 1 equivalents of sodium oxalate, yielded the binuclear complex [{(bpppa)Mn}2([mu]-C2O4)](ClO4)2 (2), which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and solid-state magnetic measurements. While 1 is mononuclear, the formation of the binuclear oxalate derivative indicates that use of the bpppa ligand does not enable isolation of a complex that is structurally relevant to a proposed 1:1 Mn(II)-oxalate adduct in the catalytic cycle of the oxalate degrading enzyme oxalate decarboxylase.     

Micellar and associated thermodynamic properties of binary mixtures of alkyl triphenyl phosphonium bromides in ethylene glycol and water mixtures

Micellar properties of binary combinations of a family of cationic alkyl triphenyl phosphonium bromides with varying chain length (C₁₀–C₁₆) were investigated in aqueous and aqueous ethylene glycol mixtures employing conductometric technique. The results of the mixed systems were analyzed in the light of the Regular Solution Theory and the Gibbs–Duhem equation to evaluate the composition of the mixed micelle, the activity coefficients, and the interaction parameter (β). The excess free energy and the other related thermodynamic parameters of mixing were calculated and discussed in terms of the stability of the mixed micelles in the presence of an ethylene glycol additive. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.