Calculation of electric field–temperature (E,T) phase diagram of a ferroelectric liquid crystal near the SmA–SmC_α~* transition

In this work we perform a theoretical calculation in order to reconstitute the(E–T) phase diagram of a chiral smectic liquid crystal in the vicinity of the SmA–SmC_α~* transition. This reconstruction is carried out on the basis of a thermodynamic calculation of the slope of the curve joining the SmC_α~* domain and the unwound SmC~*. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations.     

Tonal prediction of a faulty axial fan

The current techniques for monitoring and diagnostics of rotating machines to their conditional predictive maintenance mainly are based on vibration monitoring. In this research, experimental and theoretical methods to predict the tonal noise of a faulty fan are developed and validated. These methods can be used on identifying defects of an axial fan based on an acoustic monitoring in situations where it is necessary to operate remotely due to the inaccessibility of the areas of event defects.     

Darstellung und eigenschaften von und reaktionen mit metallhaltigen heterocyclen: XXV. Synthese und eigenschaften neuer platina- und rhodacycloalkane durch substitution und oxidative addition einer CCl-bindung

The platinacyclopentane derivative [Cl(CH₂)₃R₂P](Cl)$\text{PtPR}{}_2\text{CH}{}_2\text{CH}{}_2\text{CH}{}_2$ is formed by action of Cl(CH₂)₃PR₂ on Pt(COD)₂ in n-hexane via the not isolable Pt[PR₂(CH₂)₃Cl]₂ (R  C₆H₁₁) by oxidative addition of a CCl bond to platinum. [μ-CIRh(CO)₂]₂ reacts in benzene with Cl(CH₂)₃PR₂ under partially CO substitution to give the stable intermediate Cl(OC)Rh[PR₂(CH₂)₃Cl]₂. In boiling toluene oxidative addition of a CCl bond to rhodium occurs under formation of the phospharhodacyclopentane [CI(CH₂)₃R₂P] Cl₂(OC)-$\text{RhPR}{}_2\text{CH}{}_2\text{CH}{}_2\text{CH}{}_2$ (R  C₆H₅). The ³¹P{¹H}-NMR spectra of the rhodium compound is characterized by an ABX system, that of the platinum by superposition of an ABX pattern with an AB spectrum.     

Oxidative degradation of phenol in aqueous media using ultrasound

The degradation of phenol with ultrasound and the influence of several parameters - hydrostatic pressure, nature of the dissolved gas, frequency of the ultrasound - have been studied. Primary degradation products are dihydroxy benzenes and quinones. These products are further degraded upon time into low molecular carboxylic acids. COD reduction can be increased by the addition of Raney nickel. Based on the determination of the degradation products by HPLC and HPICE, a reaction scheme can be suggested.     

Enolizable Carbonyls and N,O‐Acetals: A Rational Approach for Room‐Temperature Lewis Superacid‐Catalyzed Direct α‐Amidoalkylation of Ketones and Aldehydes

An efficient catalytic room‐temperature direct α‐amidoalkylation of carbonyl donors, that is, ketones and aldehydes with unbiased N,O‐acetals, is described. Sn(NTf₂)₄ is an optimal catalyst to promote this challenging transformation at low loading and the reaction shows promising scope. A comprehensive and rational evaluation of this reaction has led to the establishment of an empirical scale of nucleophilic reactivity for a broad set of ketones that should be helpful in the synthetic design and development of carbonyl α‐functionalization methods.     

Chemoselective preparation of disymmetric bistriazoles from bisalkynes

Best of both worlds, molecules bearing two alkyne groups, activated and unactivated, can selectively react on the activated one in a copper-free version of Huisgen’s reaction to form a first triazole ring, with a good selectivity toward the 1,4-isomer, which is solely isolated by a simple trituration procedure. The other alkyne function is then submitted to the selective reaction using a polymer-supported copper(I) catalyst to form a second triazole ring. This gave access to disymmetric bistriazoles without the need of protection using simple, easy, and fast procedures.     

Cristallisation de LiFe5O8 dans un verre 0,9 Li2B2O4O,1 LiFe5O8: C. Chaumont and J.C. Bernier,Départment Science des Matériaux,Ecole Nationale Supérieure de Chimie de Strasbourg, 1, rue Blaise Pascal,B.P. 296/R8, 67008 Strasbourg Cédex,France

The LiPO₃-La(P₃O₉) system was studied by microdifferential thermal analysis. The only new compound observed in the system was LiLa(PO₃)₄, melting incongruently at 960°C. A eutectic appears at 640°C, for the mixture containing 5 mole% LaP₃O₉. Crystallographic data and powder diagrams of the new compound are given. The LiLa(PO₃)₄ is an LiNd(PO₃)₄ isotype. It crystallises in the monoclinic system C2/c with a unit cell a = 16.53 (3), b = 7.08 (3), c = 9.88 (2) Å, β = 126.42 (5), and Z = 4.     

Reconstruction of a defect in an open waveguide

The paper is concerned with the reconstruction of a defect in the core of a two-dimensional open waveguide from the scattering data. Since only a finite numbers of modes can propagate without attenuation inside the core, the problem is similar to the one-dimensional inverse medium problem. In particular, the inverse problem suffers from a lack of uniqueness and is known to be severely ill-posed. To overcome these difficulties, we consider multi-frequency scattering data. The uniqueness of solution to the inverse problem is established from the far field scattering information over an interval of low frequencies.