Role of the ionic reactions in teaching and research in Finland

Summary The status of ionic reactions in the chemistry curricula of the Finnish universities is outlined. In analytics their role is evidently changed. Qualitative analysis is no longer carried out by means of ionic reactions, but in modern instrumental methods of analysis these reactions are needed in sample preparation. Additionally, the ionic reactions are still important in teaching of analytical and inorganic chemistry. However, this topic should partly be taught already in the secondary school.     

Crystal structure, thermal behaviour, protonation and mass spectroscopic studies of racemic 4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole hydrochlorides

The crystal structure, thermal behaviour, mass spectrum and protonation of 4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole (medetomidine) hydrochloride have been investigated. The title compound crystallizes in both hydrated and anhydrous forms, and their structures have been determined by three-dimensional X-ray structure analysis. The crystals of the anhydrous form are monoclinic and those of the hydrated form (containing one hydrate water molecule) are triclinic with unit-cell dimensions: a = 23.861(9), b = 7.721(4), c = 22.037(9) A, beta = 140.20(4) degrees, Z = 8, and space group C2/c, and a = 7.841(4), b = 8.380(3), c = 12.743(6) A, alpha = 93.66(3), beta = 102.90(3), gamma = 116.85(3) degrees, Z = 2, and space group P1, respectively. Thermal decomposition of the title compound has been interpreted from the TG, DTG and DSC curves with the help of mass spectrometry. Medetomidine hydrochloride monohydrate decomposes in four stages. The first is dehydration at 45-100 degrees C, the second is evaporation of HCl and medetomidine base at 200-320 degrees C, and the third and fourth are decomposition at 340-570 degrees C. The protonation constant is 7.04 in aqueous 0.1 M NaClO4 (25 degrees C).     

Catalytic effect of sodium chloride on limestone calcination and sulphation — electron microscopy and eds studies

Thermogravimetric studies on the influence of sodium chloride on the kinetics of limestone sulphation were supported by scanning electron microscopy and energy dispersive X-ray microanalysis.On the basis of morphological observations on calcined and sulphated limestone and elemental microanalysis in an electron microprobe it was found that NaCl affects the sintering, favouring the formation of more compact structures of rounded crystallites during sulphation. Chlorine is largely lost during sulphation. Capacity of the sorbents under both TG and FBC conditions depends strongly on when and how the NaCl is introduced.

---

Zusammenfassung In Verbindung mit Scanning Elektronenmikroskopie und Röntgenmikroanalyse wurden thermogravimetrische Untersuchungen des Einflusses von Natriumchlorid auf die Kinetik der Sulfierung von Kalkstein durchgeführt.Auf der Grundlage von morphologischen Beobachtungen an kalziniertem und sulfiertem Kalkstein und durch Elementarmikroanalyse in einem Elektronenstrahlmikroanalysator wurde festgestellt, daß NaCl das Sintern beeinflußt. Infolgedessen wird bei der Sulfierung die Entstehung von abgerundeten Kristalliten begünstigt. Chlor wird während der Sulfierung größtenteils abgegeben. Die Kapazität der Sorptionsmittel hängt sowohl bei TG als auch bei FBC stark davon ab, wann und wie das NaCl eingebracht wurde.

---

. , , . . , .

---

---

The authors wistl to thank Prof. E. M. Bulewicz of the Technical University of Cracow for helpful discussions and Mr. S. Sivonen of the University of Oulu for making available the facilities the SEM and EDS-X-ray microanalysis at the Institute of Electron Optics.     

Analysing local algorithms in location-aware quasi-unit-disk graphs

A local algorithm with local horizon r is a distributed algorithm that runs in r synchronous communication rounds; here r is a constant that does not depend on the size of the network. As a consequence, the output of a node in a local algorithm only depends on the input within r hops from the node.We give tight bounds on the local horizon for a class of local algorithms for combinatorial problems on unit-disk graphs (UDGs). Most of our bounds are due to a refined analysis of existing approaches, while others are obtained by suggesting new algorithms. The algorithms we consider are based on network decompositions guided by a rectangular tiling of the plane. The algorithms are applied to matching, independent set, graph colouring, vertex cover, and dominating set.We also study local algorithms on quasi-UDGs, which are a popular generalisation of UDGs, aimed at more realistic modelling of communication between the network nodes. Analysing the local algorithms on quasi-UDGs allows one to assume that the nodes know their coordinates only approximately, up to an additive error. Despite the localisation error, the quality of the solution to problems on quasi-UDGs remains the same as for the case of UDGs with perfect location awareness. We analyse the increase in the local horizon that comes along with moving from UDGs to quasi-UDGs.     

Stable isotope profiles of nitrogen gas indicate denitrification in oxygen-stratified humic lakes

Mid-summer N(2) profiles were analyzed from nine oxygen-stratified, humic-acid-rich lakes using a continuous flow isotope ratio mass spectrometer and a Gasbench II device. Sample preparation steps were performed under water to avoid air contamination. The instrument precision for the δ(15)N measurement was high (0.03‰), but for the whole sampling and analysis procedure the mean deviation between replicate samples was 0.13‰ for the δ(15)N measurements and 5.5% for the N(2) gas concentration analysis. The results show that the Gasbench peripheral was suitable for measurement of the (15)N natural abundance of dissolved nitrogen gas, with denitrification indicated by the oversaturation and slightly (<1‰) depleted δ(15)N values of the dissolved N(2) gas in the suboxic zones of some of the study lakes. Calculated values for the denitrified (excess) N(2) varied between -5.3 and 0.7‰. The denitrification potential was determined using the (15)N tracer method, with results showing nitrate-inducible denitrification and no signs of anaerobic ammonium oxidation (anammox).     

Mass spectrometric behaviour of cyclopentane-and cyclohexane-condensed pyrimidinediones under electron impact

Mass spectral fragmentations of four cyclopentane-condensed cis-pyrimidinediones and of six cyclohexane-condensed cis- or trans-pyrimidinediones were examined using metastable ion analyses and exact mass measurements. The fragmentation patterns of all of these compounds were clearly different and also cis- and trans-fused isomers were easy to distinguish from each other by their mass spectra. In spite of the differences in their mass spectral fragmentations, all compounds formed phenylisocyanates (m/z 119 and 153) and anilines (m/z 93 and m/z 127), the structures of which were verified by collision-induced dissociation experiments.     

Detection of volatile organic sulfur compounds in water by headspace gas chromatography and membrane inlet mass spectrometry

Two gas chromatographic methods, GC-FID (flame ionization detection) and GC-ELCD (electrolytic conductivity detector) are compared in tlie analysis of volatile organic sulfur compounds (VOSCs) in water samples with a membrane inlet mass spectrometry (MIMS) technique. Carbon disulfide, ethanethiol, dimethyl sulfide, ethyl-methyl sulfide, thiophene, and dimethyl disulfide were used as test compounds. Linear dynamic ranges were found to be two decades with the GC-ELCD method and four decades with the GC-FID and MIMS methods. Detection limits were at low (μg/1 levels with the two gas chromatographic methods and clearly below μg/1 level with the MIMS method. Analysis of one sample takes 40 min with the gas chromatographic methods and five minutes with the MIMS method. The selectivity was good, especially with the GC-ELCD and the MIMS method. In addition, quantitative results obtained with spiked water samples by the three methods are compared.     

Absorption spectra of chelates of nitrosonaptholsulphonic acids with vanadaium(IV)

The absorption spectra of chelates formed by oxovanadium(IV) with five different o-nitro-sonaphtholsulphonic acids in aqueous solution are presented. All the ligands studied, 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt), 2-nitroso-1-naphthol-4-sulphonate, 2-nitroso-1-naphthol-5-sulphonate, 2-nitroso-1-naphthol-8-sulphonate and 2-nitroso-1-naphthol-4,6-disulphonate, form red-brown vanadium(IV) chelates in acid solution. Values of the first Stability constants of the complexes are reported.     

Gas and liquid chromatographic determination of some metals as their di-isobutyldithiocarbamate chelates

Summary Gas and Liquid Chromatographic Determination of Some Metals as Their Di-isobutyldithiocarbamate Chelates Both reversed-phase liquid chromatography and gas chromatography permit the elution of the di-isobutyldithiocarbamate chelates of nickel(II), copper(II) and cobalt(III) at picogram level. The palladium(II) chelate can be used as internal standard. Gas chromatography can easily be applied to determination of these metals in aqueous samples. In the liquid chromatography, contact between any free ligand remaining after extraction and metal traces in the column packing materials or metal components of the system must be minimized before the determinations commence. The results indicate a need for further study of interferences. Di-isobutyldithiocarbamate appears to be a suitable chelating agent for use in both Chromatographic methods.     

Equivariant uniformization theorem for subanalytic sets

In this paper we prove an equivariant version of the uniformization theorem for closed subanalytic sets: Let G be a Lie group and let M be a proper real analytic G-manifold. Let X be a closed subanalytic G-invariant subset of M. We show that there exist a proper real analytic G-manifold N of the same dimension as X and a proper real analytic G-equivariant map such that .