Methods for chemical analysis of contaminated soil samples--tests of their reproducibility between Nordic laboratories

In an effort to develop common analytical methods for contaminated soil samples the Environmental Authorities of the Nordic countries have, together with Nordtest, published the report Nordic Guidelines for Chemical Analysis of Contaminated Soil Samples. The aim of these guidelines has been to describe analytical methods which could be accepted in all the Nordic countries and in that way contribute to reducing the variation in the analytical results between laboratories. The methods covered, reflects environmental concerns and priorities in the Nordic countries for now, i.e. heavy metals, chlorophenols, creosote, volatile organic compounds, PCB, THC and PAH. The repeatability and reproducibility of the guideline methods were determined in a Nordic inter-laboratory test in 1996, and the results showed some variations. The analytical methods and the results from the inter-laboratory tests are given for heavy metals, chlorophenols, creosote, volatile organic compounds and PCB.     

Synthesis of the macrolide antibiotic A26771B methyl ester

The total synthesis of the title compound ($\text{1}$) is reported.     

Multiresidue method for the gas-chromatographic analysis of some polychlorinated and polybrominated pollutants in biological samples

Summary A multiresidue method for the analysis of a number of chlorinated and brominated organic compounds in biological samples has been developed. The method includes gas-chromatographic analysis of hexachlorinated and hexabrominated benzenes (HCB and HBB), polychlorinated and polybrominated biphenyls (PCB and PBB), polychlorinated phenols (PCP), guaiacols (PCG), paraffins (CP) and naphthalenes (PCN), polybrominated diphenyl ethers (PBDE) and the pesticides DDT, polychlorinated terpenes (PCC or toxaphene), chlordanes, hexachlorocyclohexanes (HCH), aldrin and dieldrin. The use of charcoal column in the clean-up procedure makes it also possible to analyze the planar PCB congeners (pPCB). Cod muscle samples were spiked with 10 and 50 times the detection levels of the compounds to be analyzed. The mean recoveries, relative to internal standards, for 40 compounds or compound groups were between 51 and 120%.     

Controlled Growth of SrxBa1−xNb2O6 Hopper- and Cube-Shaped Nanostructures by Hydrothermal Synthesis

Controlling the shape and size of nanostructured materials has been a topic of interest in the field of material science for decades. In this work, the ferroelectric material Sr_xBa_1−xNb₂O₆ (x=0.32–0.82, SBN) was prepared by hydrothermal synthesis, and the morphology is controllably changed from cube-shaped to hollow-ended structures based on a fundamental understanding of the precursor chemistry. Synchrotron X-ray total scattering and PDF analysis was used to reveal the structure of the Nb-acid precursor, showing Lindqvist-like motifs. The changing growth mechanism, from layer-by-layer growth forming cubes to hopper-growth giving hollow-ended structures, is attributed to differences in supersaturation. Transmission electron microscopy revealed an inhomogeneous composition along the length of the hollow-ended particles, which is explained by preferential formation of the high entropy composition, SBN33, at the initial stages of particle nucleation and growth.     

The influence of heat transfer coefficient on cooling time in injection molding

The cooling time of the polymer melt in injection molding is a major part of the total time of the processing cycle. Estimation of cooling time is therefore important. The effect of heat transfer coefficient, thermal conductivity and diffusivity on the cooling time is studied theoretically, showing high effects of variations in heat conductivity on cooling time.     

Chemical images of marine bio-active compounds by surface enhanced Raman spectroscopy and transposed orthogonal partial least squares (T-OPLS)

Surface enhanced Raman spectroscopy combined with transposed Orthogonal Partial Least Squares (T-OPLS) was shown to produce chemical images of the natural antibacterial surface-active compound 1,1,3,3-tetrabromo-2-heptanone (TBH) on Bonnemaisonia hamifera. The use of gold colloids functionalised with the internal standard 4-mercapto-benzonitrile (MBN) made it possible to create images of the relative concentration of TBH over the surfaces. A gradient of TBH could be mapped over and in the close vicinity of the B. hamifera algal vesicles at the attomol/pixel level.     

Strukturelle Übergänge zwischen Phosphiden,Arseniden und Arsenophosphiden der ZusammensetzungM 2P,M 2As undM 2(P1—xAsx)

Zusammenfassung Phasen der ZusammensetzungM ₂P,M ₂As undM ₂(P_1-xAs_x) wurden untersucht. Dabei istM ein Übergangsmetall (M=Cr, Mn, Fe, Co, Ni) oder ein Gemisch solcher Metalle. Es treten tetragonale, hexagonale sowie orthorhombische Strukturtypen auf, die sich alle auf ein rhomboedrisches Grundelement zurückführen lassen, in dem die Metallatome pyramidal oder tetraedrisch von Metalloidatomen umgeben sind. Dabei zeigt sich, daß das Auftreten der Strukturen nicht mit der mittleren Zahl der 3d-Elektronen des Kationenanteils zusammenhängt. Ein Strukturwechsel tetragonal hexagonal orthorhombisch läßt sich hingegen auf steigende Wechselwirkung zwischen den Metallatomen zurückführen.

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Structural transitions between phosphides, arsenides and arsenophoshides of the composition M₂ P, M₂ As and M₂(P _1—xAs_x)

A study has been made of phases of the compositionM ₂P,M ₂As, andM ₂(P_1-xAs_x) whereM is a transition metal (Cr, Mn, Fe, Co, Ni) or a mixture of such metals. Tetragonal, hexagonal and orthorhombic structural types occur, which can all be referred to a rhombohedral primary structure, with metalloid atoms in a pyramidal or tetrahedral arrangement about the metal atoms. It is found that the occurrence of the structures is not related to the average number of 3d electrons of the cationic part, but that a structural variation tetragonal hexagonal orthorhombic can be ascribed to increasing interaction between the metal atoms.

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Mit 7 Abbildungen

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Gewidmet Herrn Prof. Dr.H. Nowotny in Bewunderung fü das Werk, das die Wiener Schule geschaffen hat.     

Analysis of the dryout incident in the Oskarshamn 2 boiling water reactor

Early in 1988 dryout of fuel rods occurred in the Oskarshamn 2 boiling water reactor. During refuelling it was observed that one corner rod was damaged in each of four fuel assemblies. These were of the SVEA design, SVEA being the trade name of the ABB Atom water cross fuel. The damaged zone covered about 180° of the rod periphery facing the corner sub-channel, over a stretch of about 30 cm with the upper end just below the last downstream spacer.

The dominating cause of the dryout was re-use of fuel channels for ordinary 64-rod fuel, which were located in neighbouring positions to the SVEA fuel. The re-used channels showed excessive bowing because of irradiation. This bow increased the water gap between the fuel assemblies, thus increasing the neutron moderation and the local power around one corner of the SVEA fuel. This and some other factors caused the local peaking factor for the corner rod to increase from 1.04 to 1.38.

The flow and power conditions in the damaged fuel assemblies were calculated by means of the POLCA, PHOENIX, CASMO and CONDOR computer programs. The results of these calculations were used as a base for dryout predictions, which were carried out employing eight correlations, which are available in the open literature. The Barnett, the Becker and the Bezrukow correlations predicted the dryout power within 1%. Also the Condie & Bengston, the EPRI and the XN-1 correlations yielded very good results with accuracies of, respectively, −5.1, −2.3 and 7.3%. The Becker, the XN-1, the Bezrukow and the Condie & Bengston correlations predicted dryout to occur inside of the observed dryout zone of 30 cm length.

It is concluded that the dryout in the Oskarshamn 2 nuclear power plant was not caused by any faults in the design or manufacture of the SVEA fuel, and that the re-use of fuel channels should not be permitted.     

An experimental study of the effect of the axial heat flux distribution on the dryout conditions in a 3650-mm long annulus

Dryout measurements have been carried out for flow of boiling water in a 3650-mm long annulus. Eight different axial heat flux profiles, typical for BWRs, as well as one with uniform heat flux have been studied. It was found that for the present geometry the effect of the axial heat flux profile upon the total dryout power was rather small or in the range of ± 6 per cent.