Experimental investigation of high-mach-number 3D hydrodynamic jets at the national ignition facility

The first hydrodynamic experiments were performed on the National Ignition Facility. A supersonic jet was formed via the interaction of a laser driven shock ( approximately 40 Mbar) with 2D and 3D density perturbations. The temporal evolution of the jet's spatial scales and ejected mass were measured with point-projection x-ray radiography. Measurements of the large-scale features and mass are in good agreement with 2D and 3D numerical simulations. These experiments provide quantitative data on the evolution of 3D supersonic jets and provide insight into their 3D behavior.     

Photon-catalyzed bound—continuum processes: Post-saturation fluorescence quenching and huge enhancement of fragments in I2

With accurate experimental values of energies, transition moments and decay rates as input, our calculated results show that photon-catalyzed bound-continuum processes can be observed for the first time using I₂ in a cell or a molecular-beam experiment at laser intensifies as low as 10⁷ W/cm² and 10⁵ W/cm², respectively. Two new features, post-saturation quenching of fluorescence and huge (>150-fold) enhancement of fragments, are shown.     

X-ray fluorescence determination of niobium in iron-niobium alloys

Summary An X-ray fluorescence method is described for the determination of niobium in iron-niobium alloy in the concentration range from 0.1–2% of niobium. The sample is dissolved in a mixture of nitric and hydrofluoric acid and is converted to a stable oxide. This oxide is uniformly ground with boric acid and a weighed quantity of it is pressed into a circular pellet. The pellet is exposed to an X-ray beam from a tungsten target. The resulting fluorescent X-ray beam is dispersed using an LiF crystal and the intensity of the NbK -line is measured by a scintillation counter. A set of synthetic standards covering the above range is prepared using highpurity chemicals and a working curve for the estimation of niobium is established. The accuracy of the method is checked by analysing synthetic samples. The standard deviation of the method ranged from 0.5% at 5% Nb to 3.5% at 0.1% of Nb concentration.

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Röntgenfluorescenzspektroskopische Niobbestimmung in Eisen-Niob-Legierungen

Zusammenfassung Die Methode erlaubt eine Niobbestimmung im Konzentrationsbereich von 0,1–2% Niob. Die Probe wird in Salpetersäure/Flußsäure gelöst und in ein stabiles Oxid überführt, das mit Borsäure vermahlen und zu einer Tabelette gepreßt wird. Zur Röntgenfluorescenzmessung (W-Röhre, LiF-Kristall) wird die NbK -Linie herangezogen (Szintillationszähler). Mit Hilfe hochreiner Reagentien wurden synthetische Standards für den genannten Konzentrationsbereich hergestellt. Die Genauigkeit wurde mit Hilfe synthetischer Proben überprüft (Standardabweichung 0,5 % bei 5% Nb, 3,5% bei 0,1% Nb).

     

A study of refractive-index of non-aqueous solutions of magnesium-caprate and laurate

Summary The refractive index of non-aqueous soap solutions of magnesium caprate and laurate has been studied. The refractive index for the solution of these soaps in alcohols increases with the increase in the soap concentration, whereas in the case of hydrocarbons it decreases with the increase in the concentration of the soap.R _exp has been calculated with the help ofLorenz andLorentz equation. The calculated values of the molar refraction of the soaps changes with, the concentration of the soaps which indicates that the sizes of the micelle changes with the concentration. This supports the conclusions obtained from the viscosity measurements.

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Zusammenfassung Der Brechungsindex nichtw?\riger Seifenl?sungen von Magnesiumcaprat und -laurat wurde untersucht. Für L?sungen dieser Seifen in Alkohol w?chst er mit steigender Seifenkonzentration, im Falle der Kohlenwasserstoffe nimmt er dagegen mit steigender Seifen konzentration ab. Die experimentell berechnete Refraktion gem?\ derLorenz-Lorentz-Formel für die Seifen ?ndert sich mit der Seifenkonzentration, ein Zeichen, da\ die Mizellgr?\en von der Konzentration abh?ngen. Dies best?tigt Schlüsse aus Viskosit?tsmessungen.

     

First report of Zn2+ sensing exclusively at mesoscopic interfaces

We present a simple but unique, new probe 1-pyrenyl-methyl-bis(2-picolyl) amine (Pybpa) that selectively senses interfacially bound Zn2+ ions while being completely silent towards Zn2+ in bulk water.     

Patterned assembly of Yarrowia lipolytica yeast cells onto thermally evaporated octadecylamine films

Thermally evaporated patterned films of the lipid, octadecylamine (ODA), have been used in the immobilization of the hydrocarbon-degrading cells, Yarrowia lipolytica. The immobilization of the yeast cells occurs on hydrophobic surfaces presented by the lipid film elements in the patterned structure, the attachment of the cells to the lipid film occurring possibly through hydrophobic interactions between the hydrocarbon chains of the fatty amine film and the cell wall of the yeasts. It is observed that the cell immobilization is extremely faithful to the underlying lipid template indicating potential use in tissue engineering as well as materials applications involving specific enzyme-based biotransformations.     

Critical behavior and resonance excitation in the thermodynamics of extended hadrons

A system of spatially extended non-interacting hadrons generally leads at sufficiently high density to a phase transition from “gas” to “solid”. Here we study the effect of interaction, in form of an exponential resonance excitation spectrum (dual resonance model, statistical bootstrap model), on this phenomenon. While the presence of resonances significantly lowers the critical temperature, the finite size of the hadrons prevents the occurrence of the thermodynamic singularity associated with an exponential resonance spectrum in the case of point-like constituents.     

Reaction of enyne triflates with nucleophiles

Reaction of nucleophiles with enyne triflates R₁R₂CC(OTf)CCR₃1, via an S_N-2′ process, results in functionalized enynes by way a 1,3-hydride shift from the initially formed butatrienes.