Assessment of the Nd/U ratio for the quantification of neodymium in UO2

The secondary ion energy spectrum of uranium depends on the experimental conditions, which is a problem for the application of a relative sensitivity factor (RSF) procedure for the measurement of the Nd concentration in UO₂. This is interpreted as due to the dependence of the sputtering and ionisation yields of uranium on the oxidation state of the surface. Three experimental procedures are being tested to cope with this difficulty.     

High-performance liquid chromatographic analysis of cyclizine and its metabolite,norcyclizine in biological fluids using solid phase extraction

Summary A high-performance liquid chromatographic analysis of cyclizine and its metabolite, norcyclizine in biological fluids using protryptiline hydrochloride as internal standard is described. The drug and metabolite were extracted from the relevant biological matrix using a solid-phase extraction procedure combined with a simple phase separation step prior to chromatographic analysis. The separation was achieved on a reversed-phase C₁₈ column (10 μm) using acetonitrile — 0.05 M (pH=3) phosphate buffer (40:60), as the mobile phase with UV detection at 200 nm. Calibration curves were linear over the entire concentration range 5–100 ng/ml for cyclizine in serum and urine and for norcyclizine in urine. Precise quantitative analysis with relative standard deviations of <5 % was achieved.     

Determination of flumequine in channel catfish by liquid chromatography with fluorescence detection.

Rapid methods are described for determination of flumequine (FLU) residues in muscle and plasma of farm-raised channel catfish (Ictalurus punctatus). FLU residues were extracted from tissues with an acidified methanol solution, and extracts were cleaned up on C18 solid-phase extraction cartridges. FLU concentrations were determined by liquid chromatography (LC) using a C18 analytical column and fluorescence detection (excitation, 325 nm; emission, 360 nm). Mean recoveries of FLU from fortified muscle were 87-94% at 5 levels ranging from 10 to 160 ppb (5 replicates per level). FLU recoveries from fortified plasma were 92-97% at 5 levels ranging from 20 to 320 ppb. Limits of detection (signal-to-noise ratio, 3:1) for the method as described were 3 and 6 ppb for muscle and plasma, respectively. Relative standard deviations (RSDs) for recoveries were < or = 12%. Live catfish were dosed with 14C-labeled or unlabeled FLU to generate incurred residues. Recoveries of 14C residues throughout extraction and cleanup were 90 and 94% for muscle and plasma, respectively. RSDs for incurred FLU at 2 levels in muscle and plasma ranged from 2 to 6%. The identity of FLU in incurred tissues was confirmed by LC/mass spectrometry.     

The role of substituents on the addition of muonium to aromatics: As seen through muonium-radicals in allyl benzene compared to styrene,and from hammett parameters in aqueous solution

Muonium-radicals resulting from insertion into the benzene ring are found to be much more prevalent in allyl benzene (C₆H₅CH₂CH=CH₂) than in styrene (C₆H₅CH=CH₂). The salient implication of this comparison is that intramolecular rearrangements preceeded the μSR observation for the case of styrene. In turn, this suggests that muonium-containing free radicals, as seen directly by kilogauss transverse field μSR, are not necessarily theprimary radicals. Therefore, the elucidation of mechanism (and identification of the precursor) of Mu-radical formation is further complicated by the fact that the observations may refer to thermodynamically more stable secondary radicals-those resulting from a variety of intra-or inter-molecular relaxations or exchanges. Primary kinetic selectivities of thermalized muonium atom addition reactions can be determined, however, through the substituent effect on the Hammett linear free energy parameter in dilute solution. Results have been obtained for substituted benzenes and benzoic acids. Muonium apparently has a mild nucleophilic character. And, most interestingly, this is opposite to that of its heavy isotope hydrogen.     

Laser fluorescence on radio-active isotopes produced in very low yield

East particle-photon coincidence techniques, developed at Daresbury with strontium isotopes, allow ultrasensitive laser fluorescence spectroscopy of beams of radio-active isotopes which can only be produced in very low yields. The technique has now been applied to neutron-deficient barium isotopes down to¹²⁰Ba. From measured hyperfine splittings and isotope shifts, nuclear moments and changes in mean square radii have been determined. The work has revealed an abrupt increase in the mean square radius for¹²¹Ba large enough to disrupt the systematic staggering of nuclear size seen for the series. In a recent experiment an isomeric state of¹²⁷Ba with a half-life of about 2 seconds has been produced in a very low yield; nevertheless we have succeeded in obtaining a fluorescence spectrum.     

Zur volumetrischen Bestimmung des Zinks

Ohne Zusammenfassung     

A complexity approach to sustainability – Stafford Beer revisited

There is wide acceptance of the need for a more holistic approach to sustainability. However, practical solutions remain elusive and tend to exhibit underlying conflicts between different paradigms and their associated methodologies. This paper argues the need to wield analytical tools that themselves embody the principles of systemic, ecological thinking. We present here a theoretical framework based on complexity science – focused on organisational and second order cybernetics – that highlights our understanding of the concept of sustainability. The paper goes on to reflect upon how current practice would benefit from such an approach.     

On-line nuclear orientation and relaxation studies of Cs isotopes

The hyperfine field of CsFe has been measured to be (+)40.8(0.7)T, using the technique of on-line low temperature nuclear orientation. The time dependent relaxation of¹²¹Cs^m Fe has also been investigated using a new technique, giving a Korringa constant C_k of 0.059 (15) sK. From this, an effective relaxation time of 3.0 (0.8)s can be deduced for the short lived¹¹⁸Cs^m(T_1/2=17s). This value has then been used to extract the magnetic moment of¹¹⁸Cs^m to be |μ|=5.4 (1.1) nm.