Active centers, catalytic behavior, symbiosis and redox properties of MoV(Nb,Ta)TeO ammoxidation catalysts

Selective as well as waste forming active centers were defined for MoVNbTeO and MoVTaTeO catalysts in the ammoxidation of propane to acrylonitrile and all catalytic functionalities were assigned to specific elements at the respective active centers. Symbiosis between M1 and M2 phases of these catalysts was observed, with phase cooperation being more extensive in the Nb than Ta containing compositions. The difference in catalytic effectiveness arises most likely because contact and surface area exposure of the two respective, cooperating phase pairs are not equal. The M1 phase of the catalysts is reducible by propane and ammonia in the absence of dioxygen and is regenerable to its original, fully oxidized state by dioxygen (air). No structural collapse is observed even after 120 C₃H₈ + NH₃ reduction pulses. The so induced reduction of the catalyst extends up to 70 layers deep. The product distribution over the first few pulses is very similar to that under catalytic conditions, supporting the concept that lattice oxygen is involved in the catalytic ammoxidation process. Therefore, the ammoxidation of paraffins is a redox process, as is of course the well-known olefin ammoxidation process.     

The beta-gal interferon assay: a new, precise and sensitive method

Cells of a human glioblastoma line were stably transfected with a glial fibrillary acidic protein (GFAP) promoter sequence/lacZ reporter gene. Following this modification, they produced Escherichia coli beta-galactosidase constitutively in amounts that could be measured through their conversion of an added fluorophore into a product readily estimated by fluorimetry. Human interferons (IFN) selectively and in a dose-dependent manner reduce the formation of beta-galactosidase in this system. We have used it as the basis for a novel assay that is sensitive (4-40 pg/ml), precise, completed in 30 h, and applicable to both type I and type II human IFNs. Statistical analysis showed interassay relative standard deviations ranging from 5% to 11%, and most individual assays revealed potencies with limits of error within 85%-115%. Neither partially trypsin-digested IFN nor the other cytokines and mitogens we tested reacted in this system, except for tumor necrosis factor-alpha (TNF-alpha). The high selectivity was further shown by the loss of response to IFN in the presence of the appropriate specific anti-IFN or anti-IFN-gamma receptor antibodies.     

1.4 Fast volume determination using a differential capacitance manometer

The reliable pressure readings with a capacitance manometer are the basis for a new type of instrument designed for accurate and rapid measurements of capillary volumes. The basic measuring principle is based on expansion of air atmospheric pressure enclosed in a known volume into a pre-evacuated cylinder so that the enclosed volume will cause a reduced pressure in the cyllinder. The same is done with the air in an unknown volume into another identical pre-evacuated cylinder. A differential capacitance manometer is then used to measure the difference in pressure between the two cylinders with a high degree of accuracy. This difference in pressure is shown to be ainear function of the difference in volume between the unknown and the known volume. The accuracy and repeatability of the instrument is better than 0.5%.     

Plastic deformation at a stably growing crack tip

The deformations around the tip of a straight, through-the-thickness crack in sheets of cellulose nitrate, celluloid, in tension have been studied, as well before as after the onset of stable crack growth. A tensile testing apparatus and a device for engraving a fine grid directly on the specimen sheet have been designed. The development of the plastic enclave also after the start of stable crack extension has been studied in connexion with investigations of the deformations in gross fields of size up to 30 × 40 mm² performed on a digital computer (line element length 1 or 0.5 mm, virgin crack length 80 mm). Unexpected deformations very close to the crack tip were found in the near field where line elements of length 50 µm were analyzed. A modified Dugdale model where the cohesive stresses vary linearly is examined and is applied on polyvinylehloride, PVC, specimen the thickness of which is strongly reduced near the crack tip. A method for measurement of thickness changes of the order of a few µm by tracing isohypses is described. Finally, to enable comparison with the experimental results, the elastic deformation pattern for a square mesh in the plane strain and plane stress case is obtained by a digital computer.

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Zusammenfassung Es wurden die Verformungen an der Spitze eines geraden, über die gesamte Dicke durchgehenden Risses in Spannungen unterworfenen Tafeln aus Zellulosenitrat (Zelluloïd) untersucht. Dies geschah sowohl vor als auch nach der Einstellung einer gleichmäßigen Rißfortpflanzungsgeschwindigkeit. Hierzu wurde eine Zugversuchsapparatur sowie ein Verfahren zur Gravierung eines Rasters, direkt auf die Probe, entwickelt.Die Ausbildung der plastischen Enklave, auch nach Einstellung einer gleichmäßigen Rißausweitung, wurde in Verbindung mit Studien der Verformung in Grobrastern his 30 × 40 mm mittels Digitalrechnern, untersucht (Länge einer Elementarlinie l oder 0,5 mm; Originallänge des Risses 80 mm). Direkt an der Rißspitze, wo Elementarlinien mit einer Länge von 50 µm untersucht wurden, konme man unerwartete Verformungen feststellen. Es wurde ein abgewandeltes Dugdale-Modell bei dem die Kohäsionsspannungen sich linear verändern untersucht and auf Polyvinylchlorid PVC-Proben, deren Dicke sich an der Rißspitze stark reduziert, angewandt. Es wird ein Verfahren zur Messung von Änderungen der Dicke um wenige µm beschrieben. Um einen Vergleich mit den experimentellen Ergebnissen zu ermöglichen, wird zum Schluß mit Hilfe eines Digitalrechners das elastische Verformungsmodell für Quadratraster, im Falle planer Verformung and eines planen Spannungszustandes berechnet.

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Résumé On a étudié les déformations qui se produisent au voisinage de l'extrémité d'une fissure droite et traversante dans des feuilles de nitrate de cellulose (celluloid) soumises à traction, et ce avant et après établissement d'un régime stable de propagation. A cet effet, on a mis au point un équipement d'essai de traction et une technique permettant de tracer une grille directement sur l'éprouvette. Le développement d'une enclave plastique dès que l'éxtension de la fissure devient stable a été etudie en recherchant les déformations survenant dans des réseaux grossiers, allant jusqu'à 30 × 40 mm², a l'áide d'un calculateur digital (longueur d'une ligne élémentaire: 1 ou 0,5 mm, longueur de fissure initiale: 80 mm). Dans un réseau plus fin, où les lignes élémentaires avaient une longueur de 50 microns, on a analysé, au voisinage immédiat de l'éxtrémité de la fissure, des déformations inattendues.On a examiné l'ápplication d'un modèle du Dugdale modifié, où les contraintes de cohésion varient linéairement, à des éprouvettes de PVC, dont l'épaisseur subit des réductions considérables près de l'extrémité de la fissure. On décrit une méthode de mesure des variations d'épaisseur de l'órdre de quelques microns, qui est basée sur le tracé de courbes de niveaux.Enfin, pour permettre une comparaison avec les résultats expérimentaux, on a établi par un calculateur digital l'állure de la déformation élastique dans un réseau carré pour les cas d'état plan de déformation et d'état plan de tension.

     

Internet vs. paper and pencil administration of questionnaires commonly used in panic/agoraphobia research

The aim of this study was to investigate the psychometric properties of Internet administered questionnaires used in panic research. Included were 494 people who had registered for an Internet-based treatment program for panic disorder (PD). Participants were randomly assigned to fill in the questionnaires either on the Internet or the paper-and-pencil versions, and then to fill in the same questionnaires again the next day using the other format. The questionnaires were the body sensations questionnaire [BSQ; Chambless, D. L., Caputo, G. C., Bright, P., & Gallagher, R. (1984). Assessment of fear of fear in agoraphobics: the body sensations questionnaire and the agoraphobic cognitions questionnaire. Journal of Consulting and Clinical Psychology, 52, 1090–1097], agoraphobic cognitions questionnaire [ACQ; Chambless, D. L., Caputo, G. C., Bright, P., & Gallagher, R. (1984). Assessment of fear of fear in agoraphobics: the body sensations questionnaire and the agoraphobic cognitions questionnaire. Journal of Consulting and Clinical Psychology, 52, 1090–1097], mobility inventory [MI; Chambless, D. L., Caputo, G., Jasin, S., Gracely, E. J., & Williams, C. (1985). The mobility inventory for agoraphobia. Behaviour Research and Therapy, 23, 35–44], beck anxiety inventory [BAI; Beck, A. T., Epstein, N., Brown, G., & Steer, R. A. (1988). An inventory for measuring clinical anxiety: psychometric properties. Journal of Consulting and Clinical Psychology, 56, 893–897], beck depression inventory II [Beck, A. T., & Steer, R. A. (1996). Beck Depression Inventory. Manual, Svensk version (Swedish version). Fagernes, Norway: Psykologiförlaget, AB], quality of life inventory [QOLI; Frisch, M. B., Cornell, J., Villanueva, M., & Retzlaff, P. J. (1992). Clinical validation of the quality of life inventory. A measure of life satisfaction for use in treatment planning and outcome assessment. Psychological Assessment, 4, 92–101], and montgomery Åsberg depression rating scale [MADRS; Svanborg, P., & Åsberg, M. (1994). A new self-rating scale for depression and anxiety states based on the comprehensive psychopathological rating scale. ACTA Psychiatrica Scandinavica, 89, 21–28]. Results showed largely equivalent psychometric properties for the two administration formats (Cronbach’s α between 0.79 and 0.95). The results also showed high and significant correlations between the Internet and the paper-and-pencil versions. Analyses of order effects showed an interaction effect for the BSQ and the MI (subscale Accompanied), a main effect was identified for ACQ, MI-Alone, BAI and BDI II. However, in contrast to previous research, the Internet version did not consistently generate higher scores and effect sizes for the differences were generally low. Given the presence of an interaction effect, we recommend that the administration format should be stable in research across measurement points. Finally, the findings suggest that Internet versions of questionnaires used in PD research can be used with confidence.