Vinylic MIDA Boronates: New Building Blocks for the Synthesis of Aza‐Heterocycles

A two‐step synthesis of structurally diverse pyrrole‐containing bicyclic systems is reported. ortho‐Nitro‐haloarenes coupled with vinylic N‐methyliminodiacetic acid (MIDA) boronates generate ortho‐vinyl‐nitroarenes, which undergo a “metal‐free” nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex “drug‐like” molecules. Interestingly, an ortho‐nitro‐allylarene derivative furnished a cyclic β‐aminophosphonate motif.     

Fabrication of material-independent morphology gradients for high-throughput applications

Gradient surfaces allow rapid, high-throughput investigations and systematic studies in many disparate fields, including biology, tribology and adhesion. We describe a novel method for the fabrication of material-independent morphology gradients, involving a two-step process of particle erosion followed by a chemical polishing procedure that preferentially removes features with a small radius of curvature as a function of time. Gradients are fabricated on aluminium surfaces, but they may be readily transferred to other materials via a replication technique, which allows for the production of identical roughness gradient samples with any chosen surface chemistry. The gradients have been characterized by means of scanning electron microscopy and optical profilometry. Standard roughness parameters (Ra, Rq, Rz, Sm and Sk) were calculated from optical profilometry data. The roughness has also been assessed over different wavelength windows by means of a fast Fourier transformation approach.     

Differential effects of synchronous and asynchronous multifinger coactivation on human tactile performance

Background  

Repeated execution of a tactile task enhances task performance. In the present study we sought to improve tactile performance with unattended activation-based learning processes (i.e., focused stimulation of dermal receptors evoking neural coactivation (CA)). Previous studies show that the application of CA to a single finger reduced the stationary two-point discrimination threshold and significantly increased tactile acuity. These changes were accompanied by an expansion of the cortical finger representation in primary somatosensory cortex (SI). Here we investigated the effect of different types of multifinger CA on the tactile performance of each finger of the right hand.     

Magnetism in very thin films of permalloy measured by spin polarized cascade electrons

The spin polarizationP of the low energy cascade electrons excited with a primary unpolarized electron beam is measured with ultrathin films of permalloy (Ni₈₀Fe₂₀) as a function of film thickness, external magnetic field, and temperatureT. Surface adsorbates of small concentrations of less than 10% of a monolayer can change the Curie point and the saturation value ofP ₀(T0) by as much as 30%. The Ta-substrate induces a magnetically dead region in permalloy. Conventional spin wave theory cannot account for the observed smallT-dependence of the magnetizationM. Films on a nonmagnetic substrate are compared to similar films coupled to bulk permalloy over an interface of Ta. TheT-dependence ofM with the coupled films can be explained by spin wave theory. At lowT, the films coupled to the bulk exhibit a faster decrease ofM than the uncoupled films. We propose that this thermal stabilization of the magnetization in very thin ferromagnetic films is due to quenching of the long wavelength spin modes.     

Automatisches Verfahren zur Bestimmung des Bleioxidgehalts von Grauoxid durch Messung der L?sungsw?rme

Zusammenfassung Für das zur Herstellung von Bleibatterien verwendete Grauoxid (bestehend aus einem feinteiligen Gemisch von ca. 60 bis 90% Bleioxid, PbO, und einem Rest metallischem Blei) wurde ein Verfahren zur kontinuierlichen bzw. quasikontinuierlichen, automatischen Bestimmung des PbO-Gehaltes an den Fertigungsanlagen benötigt. Eine schnelle Analyse mit vergleichsweise geringem Aufwand war durch Messung der Lösungswärme bei Behandlung einer abgewogenen Menge Grauoxid mit verd. Essigsäure möglich. Unter technisch bequem realisierbaren Bedingungen wurden Temperaturerhöhungen von einigen Grad erhalten. Der Einfluß verschiedener Arbeitsbedingungen, der verschiedenen PbO-Modifikationen und der Teilchengröße und -form wurde untersucht. Zur Zeit wird eine für die Fertigung bestimmte, automatische Apparatur aufgebaut, die bei einer Analysenfolge von 1 min die Bestimmung mit einer Standardabweichung unter ±1% durchzuführen gestattet.

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Automatic procedure for the determination of the lead oxide content of gray oxides by measurement of the heat of solution

A continuous or semicontinuous automatic method for the determination of the lead oxide content was needed in the manufacturing process of gray oxides (a fine particle mixture of about 60 to 90% lead oxide, PbO, and metallic lead, used in manufacturing lead batteries).A rapid determination with comparatively small effort was possible by measuring the heat of solution of a weighed amount of gray oxides treated with acetic acid. Temperature rise of a few degrees could be reached under technically realisable conditions. The influence of different working conditions, of the particle size and shape and of the PbO modifications were investigated. An automatic apparatus for the determination is at present being built and will give one determination per minute with a standard deviation of less than ±1%.

     

[(Mes3Sn)2MoO4], ein monomeres Triorganozinnmolybdat

[(Mes₃Sn)₂MoO₄], a Monomeric Triorganotin Molybdate Mes₃SnBr (Mes = 1, 3, 5‐trimethylphenyl) reacts with (NBu₄)₂[Mo₆O₁₉] in the presence of (NBu₄)OH (in CH₃CN as solvent) to form [(Mes₃Sn)₂MoO₄]. Alternatively the title compound can be obtained from the reaction of [MoO₂(acac)₂] (acac = 2, 4‐pentadionate) with Mes₃SnOH in isopropanol. [(Mes₃Sn)₂MoO₄] forms monoclinic crystals, space group C2/c, with a = 2271.6(3) pm, b = 825.2(1) pm, c = 2739.9(5) pm, β = 90.96(2)°. The crystal structure consists of isolated molecules in which a tetrahedral MoO₄ unit is connected to two terminal Mes₃Sn groups. The Mo‐O distances range from 169.6(4) to 181.1(3) pm and the Sn‐O distance is 204.8(3) pm.