Determination of maleic anhydride in occupational atmospheres

Maleic anhydride has many uses in industry, but workers' exposure to it is poorly known. Our new method allows airborne maleic anhydride to be determined with a limit of quantification of 1 microg/m3 per 12 1 of air, i.e., the concentration of about 0.01 times the occupational exposure standard (0.4 mg/m3). Air samples are collected in Tenax tubes containing sodium sulfate as a drying agent. Maleic anhydride is eluted with methyl tert.-butyl ether containing 5% acetonitrile and 0.1% acetic anhydride, and determined by capillary gas chromatography with electron-capture detection without interference from generic anhydrides. The tested method suits both long-term and short-term measurements.     

On the definition of viscosity solutions for parabolic equations

In this short note we suggest a refinement for the definition of viscosity solutions for parabolic equations. The new version of the definition is equivalent to the usual one and it better adapts to the properties of parabolic equations. The basic idea is to determine the admissibility of a test function based on its behavior prior to the given moment of time and ignore what happens at times after that.

     

Probing shapes of very neutron deficientZ≈82 nuclei using the recoil-decay tagging method

The JYFL gas-filled recoil separator, RITU, combined with efficient Ge-detector arrays has been employed in in-beam γ-ray studies of very neutron-deficient nuclei close to theZ=82 shell. Gamma-rays from nuclei produced at the few μb cross-section level have been detected.     

Collectivity in neutron-deficient Pb and Po nuclei

Lifetimes of low-lying yrast states in ¹⁸⁶Pb and ¹⁹⁴Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in ¹⁸⁸Pb up to the 8⁺ state were carried out using the recoil gating method. The deformation parameters and for the prolate (^186,188Pb) and the oblate (¹⁹⁴Po) bands, respectively, have been extracted from the measured lifetimes. 27.70.+q–     

Collectivity and configuration mixing in 186,188Pb and 194Po

Lifetimes of prolate intruder states in 186Pb and oblate intruder states in 194Po have been determined by employing, for the first time, the recoil-decay tagging technique in recoil distance Doppler-shift lifetime measurements. In addition, lifetime measurements of prolate states in 188Pb up to the 8+ state were carried out using the recoil-gating method. The B(E2) values have been deduced from which deformation parameters |beta2|=0.29(5) and |beta2|=0.17(3) for the prolate and the oblate bands, respectively, have been extracted. The results also shed new light on the mixing between different shapes.     

Properties of the 13/2+ isomeric decay in201Hg

The isomeric decay of theT _1/2=94 us isomeric state in²⁰¹Hg was studied in beam via the reaction¹⁹⁸Pt(α, n). Gamma-ray and conversion-electron spectra were recorded. From the conversion coefficients, the multipolarities of the two depopulating transitions were determined to beM 2 + 10%E 3 andE 2, respectively. These assignments give the depopulating transitions to be 13/2⁺ → 9/2^? and 9/2^? → 5/2^?, and these thus substantiate the previous suggestion that the isomeric state hasJ ^π=13/2⁺. For the 13/2⁺ → 9/2^? M 2 transition a detailed study ofE 3 andM 4 admixed amplitudes was done. The microscopic properties of the 13/2⁺ and 9/2^? states are discussed, and a comparison to the corresponding ones in^199,203,205Hg is made.     

The molecular structures of gaseous cyclopentene oxide,cyclohexene oxide and cycloheptene oxide as determined by electron diffraction

The molecular structures of gaseous cyclopentene oxide, cyclohexene oxide and cycloheptene oxide are investigated by electron diffraction. The boat conformation of cyclopentene oxide is confirmed, while a half-chair conformer is determined for cyclohexene oxide. Cycloheptene oxide is found to exist in a 66(2):34(2) conformational mixture of two chair forms.     

Determination of α-decay branching ratios for 178, 179Hg

The neutron-deficient nuclides ^{182, 183}Pb were produced at the Accelerator Laboratory of the University of Jyv?skyl? by bombarding a ¹⁰⁷Ag target with ⁷⁸Kr ions. The nuclei of interest were separated using the RITU gas-filled separator and their radioactive decays investigated using the GREAT spectrometer. Correlating the $ \alpha$ decays of these Pb isotopes with those of their respective Hg daughters allowed $ \alpha$ -decay branching ratios of $\ensuremath b_\alpha($ ^178Hg) = 89(4)% and $\ensuremath b_\alpha($ ^179Hg) = 75(4)% to be deduced.     

On the evolution governed by the infinity Laplacian

We investigate the basic properties of the degenerate and singular evolution equation which is a parabolic version of the increasingly popular infinity Laplace equation. We prove existence and uniqueness results for both Dirichlet and Cauchy problems, establish interior and boundary Lipschitz estimates and a Harnack inequality, and also provide numerous explicit solutions. The first author is partially supported by the ESF program ``Global and Geometric Aspects of Nonlinear Partial Differential Equations'