Synthesis of new tricyclic phosphines and phosphinites by intramolecular Diels-Alder reactions of trivalent phospholes

Phospholes bearing an allyl-X substituent at phosphorus tend to undergo an intramolecular Diels-Alder cycloaddition (IMDA) leading to the corresponding tricyclic derivative. When X = O or NR, the IMDA easily takes place at room temperature. When X = CH2, the IMDA slowly takes place around 110-140 degrees C, as a function to the substitution pattern of the dienic system. Two tricyclic derivatives (X = O and CH2) have been characterized by X-ray crystal structure analysis of the P-sulfides.     

Transmission of N Atoms Through PP Membranes for Nitrogen Flowing Post Discharge Sterilisation Processes

This work reports on the results of investigations conducted with three layered polypropylene (PP) membranes which were exposed to a N₂ flowing microwave (100 W) post discharge, at several flow rates (0.03–1 Slm) and at gas pressure from 0.3 to 40 Torr. The N atoms transmission through the membrane was measured from the intensity variation of the N₂, 580 nm afterglow which is related to N atom density, before and after the membranes. The results obtained showed that N-atoms penetrate and cross the membranes with a transmission factor (T _N) varying from 20 to 70% during the exposure time (15 min), depending on flow rate and gas pressure. A maximum value T _N = 0.7 (±0.05) is found for sufficient low flow rate (less than 0.1 Slm), that is for low flow gas velocity (about 2 × 10² cm s⁻¹).     

Density of O-atoms in an Afterglow Reactor During Treatment of Wool

Density of neutral oxygen atoms in the ground state has been measured during treatment of wool fabric samples. Samples were placed in an afterglow reactor with a volume of about 5 l, which was pumped with a two stage rotary pump with the nominal pumping speed of 28 m³/h. The source of the oxygen atoms was a microwave discharge operating in the surfatron mode at 2.45 GHz and adjustable output power up to 300 W. The density of O-atoms in the afterglow chamber was measured with a fiber-optics catalytic probe. For the empty reactor, the O density depended on discharge parameters and was between 0.8 and 2.8 × 10²¹ m⁻³ at 40 and 50 Pa respectively. During the treatment of wool, the O density depended largely on the exposure time. For untreated samples, the O density was below the detection limit of the probe, while prolonged treatment allowed for recovering the O density. The recovery always occurred after having submitted wool samples to the dose of the order of 10²³ atoms/m². The results were explained by oxidation of the thin lipid layer on the surface of the wool fibres.     

Pseudo-steady-state solutions for solidification in a wedge

Polubarinova-Kochina's analytical differential equation methodis used to determine the pseudo-steady-state solution to problemsinvolving the freezing (solidification) of wedges of liquidwhich are initially at their fusion temperature. In particular,we consider four distinct problems for wedges which are: freezingwith the same constant boundary temperature, freezing with thesame constant boundary heat fluxes, freezing with distinct constantboundary temperatures and freezing with distinct constant fluxesat the boundaries. For the last two problems, a Heun's differentialequation with an unknown singularity is derived, which in bothcases admits a particularly elegant simple solution for thespecial case when the wedge angle is . The moving boundariesobtained are shown pictorially.     

A Tetracoordinated Phosphasalen Nickel(III) Complex

The oxidation of a Ni^II complex bearing a tetradentate phosphasalen ligand, which differs from salen by the presence of an iminophosphorane (P?N) in place of an imine unit, was easily achieved by addition of a silver salt. The site of this oxidation was investigated with a combination of techniques (NMR, EPR, UV/Vis spectroscopy, X‐ray diffraction, magnetic measurements) as well as DFT calculations. All data are in agreement with a high‐valent Ni^III center concentrating the spin density. This markedly differs from precedents in the salen series for which oxidation on the metal was only observed at low temperature or in the presence of additional ligands or anions. Therefore, thanks to the good electron‐donating properties of the phosphasalen ligand, [Ni(Psalen)]⁺ represents a rare example of a tetracoordinated high‐valent nickel complex in presence of a phenoxide ligand.     

Densities of Active Species in R/x%(N2–5%H2) (R = Ar or He) Microwave Flowing Afterglows

Plasma Chemistry and Plasma Processing - Afterglows of R/x(N2–5%H2) (R?=?Ar or He) flowing microwave discharges are characterized by optical emission spectroscopy. Absolute...     

Approximation properties and absence of Cartan subalgebra for free Araki–Woods factors

We show that all the free Araki–Woods factors Γ^″(HR,Ut) have the complete metric approximation property. Using Ozawa–Popa?s techniques, we then prove that every nonamenable subfactor N⊂Γ^″(HR,Ut) which is the range of a normal conditional expectation has no Cartan subalgebra. We finally deduce that the type III₁ factors constructed by Connes in the ?70s can never be isomorphic to any free Araki–Woods factor, which answers a question of Shlyakhtenko and Vaes.     

Multi-class classification with probabilistic discriminant partial least squares (p-DPLS)

This work describes multi-classification based on binary probabilistic discriminant partial least squares (p-DPLS) models, developed with the strategy one-against-one and the principle of winner-takes-all. The multi-classification problem is split into binary classification problems with p-DPLS models. The results of these models are combined to obtain the final classification result. The classification criterion uses the specific characteristics of an object (position in the multivariate space and prediction uncertainty) to estimate the reliability of the classification, so that the object is assigned to the class with the highest reliability. This new methodology is tested with the well-known Iris data set and a data set of Italian olive oils. When compared with CART and SIMCA, the proposed method has better average performance of classification, besides giving a statistic that evaluates the reliability of classification. For the olive oil set the average percentage of correct classification for the training set was close to 84% with p-DPLS against 75% with CART and 100% with SIMCA, while for the test set the average was close to 94% with p-DPLS as against 50% with CART and 62% with SIMCA.     

Quantifying the reactivity of a remarkably long-lived difluorinated enol in acidic methanol via solution kinetics and electronic structure calculations

A simple enol acetal underwent rapid cleavage in acidic solution to generate a difluorinated enol, which was sufficiently long-lived to be characterized by 2D NMR in a protic solvent at ambient temperature. Density functional theory calculations on a model reaction suggest that there are significant differences in protonation transition state timing between the fluorinated and nonfluorinated enols.