Highly sensitive laser fluorimetry of europium(III) with1,1,1-trifluoro-4-(2-thienyl)-2,4-butanedione

The detection limit for tris(1,1,1-trifluoro-4-(2-thienyl)-2,4-butanediono)-europium(III) is established as 2 pg l^-1. A highly sensitive fluorimetric system consisting of a nitrogen laser and a pulse-gated photon counter is used.     

Dielectric properties of oligomers. VII. Low-molecular-weight propylene glycols

The dielectric properties of low-molecular-weight propylene glycols HO? [CH(CH₃)CH₂O]_n? H (n = 3, 4, 5) were investigated to clarify the effect of chain length on the dielectric properties. The measurement of dielectric constant and dielectric loss was carried out over the frequency range 30 Hz to 30 MHz at temperatures of ?20 to ?65°C. The static dielectric constants of these glycols are between 10 and 30, slightly smaller than values for the corresponding ethylene glycols of the same degree of polymerization. All of the Cole–Cole arcs, even that for pentapropylene glycol, can be represented by the empirical Davidson–Cole equation. The dielectric properties of homologous propylene glycols are compared with those for the ethylene glycols and are discussed in terms of the effects of chain length and intermolecular hydrogen bonds.     

An application of bis[2-(5-chloro-2-pyridylazo)- 5-diethylaminophenolato]cobalt(III) chloride to the extraction and spectrophotometric determination of sulphonated and sulphated surfactants

Bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) is proposed for the extraction and spectrophotometric determination of sulphated and sulphonated surfactants. The complex and the surfactants form ion-pairs which are extracted into benzene from O.1M hydrochloric acid. The absorbance of the benzene phase is measured at 560 nm against a reagent blank. Less than 25 mug of sodium di-(2-ethylhexyl) sulphosuccinate in 50-200 ml of sample solution is determined reproducibly by the proposed method. When applied to river water samples, the proposed method gives results which agree very well with those obtained by the standard Methylene Blue method. However, the proposed method is simpler and more sensitive than the Methylene Blue method.     

Sustainable domino Michael reaction catalyzed by a Brønsted base on silica gel: synthesis of bicyclo[2.2.2]octane-2,5-dione derivatives

Domino Michael reactions of oxophorone and its derivatives 4 with Michael partners 3 have been effected to give bicyclo[2.2.2]octane-2,5-dione derivatives 7 by a catalytic amount of a Brønsted base (NMAP-Li) generated from N-methylaminopropylated silica gel (NMAP) and n-BuLi. The NMAP pellets were efficiently reused up to six times in 86% average yield.     

A mild photoactivated hydrophilic/hydrophobic switch

Surface modification using light is one of the most powerful methods for controlling the physical and chemical properties offunctionalized surfaces. In this paper, we report on systems where soft UV irradiation (lambda = 365 nm) converts a "low" activity fluorocarbon to a "high" activity amine-functionalized surface. An amine-functionalized SAM (self-assembled monolayer) is first masked using a tertiary amine catalyzed reaction with an N-hydroxysuccinimidyl carbonyl reagent. This mild, room-temperature reaction introduces a hydrophobic photocleavable nitrobenzyl "protecting group" terminated with a fluorocarbon end-chain. UV irradiation (lambda = 365 nm) of this hydrophobic/fluorocarbon surface cleaves the nitrobenzyl residue, returning the surface to the original hydrophilic/amine-functionalized state. This provides a mild, generic method of producing surfaces with hydrophilic/hydrophobic patterns or patterned with amine functional residues. Two different protecting groups, one terminated with a single and the other with three fluorocarbon end chains, are compared. In the case of the more bulky protecting group, only a small proportion of the amine residues react, but the surface is equally hydrophobic and the amine residues equally well shielded from further reaction. Surfaces are characterized by X-ray photoelectron spectroscopy, ellipsometry, surface potential, and contact angle measurements. Images of the photopatterned SAMs were obtained using scanning electron microscopy.     

Successive Linearization Methods for Nonlinear Semidefinite Programs

We present a successive linearization method with a trust region-type globalization for the solution of nonlinear semidefinite programs. At each iteration, the method solves a quadratic semidefinite program, which can be converted to a linear semidefinite program with a second order cone constraint. A subproblem of this kind can be solved quite efficiently by using some recent software for semidefinite and second-order cone programs. The method is shown to be globally convergent under certain assumptions. Numerical results on some nonlinear semidefinite programs including optimization problems with bilinear matrix inequalities are reported to illustrate the behaviour of the proposed method.The research of the fourth author was supported in part by a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science. The research of the second author was supported by the DFG (Deutsche Forschungsgemeinschaft).     

Hall subgroups of -groups need not be -groups

In this paper, we shall give examples of -groups that have Hall subgroups that are not -groups.