Proficiency testing in analytical chemistry, microbiology and laboratory medicine: working discussions on current practice and future directions

A summary of the working group (WG) discussions on proficiency testing (PT) and external quality assessment (EQA) held at the EURACHEM Workshop, Istanbul, 3?C6 October 2011, is provided. The six WGs covered a range of issues concerned with current practice and future directions; implementing the requirements of ISO/IEC 17043 by PT/EQA providers (WG1); accrediting PT/EQA providers to ISO/IEC 17043 (WG2); pre- and post-analytical aspects in PT/EQA (WG3); evaluating participant performance in qualitative PT/EQA schemes (WG4); establishing PT/EQA schemes in developing countries (WG5); and establishing acceptability criteria in microbiology PT/EQA schemes (WG6). Delegates with different backgrounds were on each WG in order to capture a range of views and experience from a number of different sectors. Working group representatives included PT/EQA providers, participants in PT/EQA schemes and end-users of PT results such as accreditation bodies and regulatory authorities, from countries around the world.     

Amplitude variations in coarticulated vowels

This paper seeks to characterize the nature, size, and range of acoustic amplitude variation in naturally produced coarticulated vowels in order to determine its potential contribution and relevance to vowel perception. The study is a partial replication and extension of the pioneering work by House and Fairbanks [J. Acoust. Soc. Am. 22, 105-113 (1953)], who reported large variation in vowel amplitude as a function of consonantal context. Eight American English vowels spoken by men and women were recorded in ten symmetrical CVC consonantal contexts. Acoustic amplitude measures included overall rms amplitude, amplitude of the rms peak along with its relative location in the CVC-word, and the amplitudes of individual formants F1-F4 along with their frequencies. House and Fairbanks' amplitude results were not replicated: Neither the overall rms nor the rms peak varied appreciably as a function of consonantal context. However, consonantal context was shown to affect significantly and systematically the amplitudes of individual formants at the vowel nucleus. These effects persisted in the auditory representation of the vowel signal. Auditory spectra showed that the pattern of spectral amplitude variation as a function of contextual effects may still be encoded and represented at early stages of processing by the peripheral auditory system.     

Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

A comparative study of amine and silver carboxylate adducts [R₁COOAg-2(R₂NH₂)] (R₁ = 1, 7, 11; R₂ = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, ¹³C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies (¹H and ¹³C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

Open image in new window

Graphical abstract The synthesis of a series (bis)alkylamine silver(I) carboxylate complexes in nonpolar solvents were carried out and fully characterized both in the solid and solution. Carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination. The complexes form layered structures which thermally decompose forming nanoparticles stabilized only by aliphatic carboxylates.

     

On the reaction of glycidol with a secondary amine

The attempt was made to prepare an ionene like base by reacting diethylamine (DEA) with glycidol (Gly). It turned out that the reaction proceeds via two steps witch differ significantly. When the rate of added DEA to Gly in bulk becomes 1 : 13 the temperature jumps up suddenly. The product proved to be a water soluble oligomer having a molecular weight of M_n > 465 g/mol, a nitrogen content of 1.06%, and pH 9.5. Based on the ¹³C NMR and IR spectra, schemes of polyreactions were proposed according to which amine groups containing moieties of low molecular weight are formed. These subsequently function as initiators of Gly homopolymerization according to a chain mechanism.     

Role of Age and Education as the Determinant of Income Inequality in Poland: Decomposition of the Mean Logarithmic Deviation

Measures of inequality can be used to illustrate inequality between and within groups, but the choice of the appropriate measure can have different implications. This study focused on the Mean Logarithmic Deviation, the measure proposed by Theil and based on the techniques of statistical information theory. The MLD was selected because of its attractive properties: fulfillment of the principle of monotonicity and the possibility of additive decomposition. The following study objectives were formulated: (1) to assess the degree of inequality in the population and in the distinguished subgroups, (2) to determine the extent to which education and age influence the level of inequality, and (3) to ascertain what factors contribute to changes in the level of inequality in Poland. The study confirmed an association between the level of education and the average income of the groups distinguished on this basis. The education level of the household head remains an important determinant of household income inequality in Poland, despite the decline in the “educational bonus”. The study also found that differences in the age of the household head had a smaller effect on income inequality than the level of education. However, it can be concluded that the higher share of older people may contribute to an increase in income inequality between groups, as the income from pension in Poland is more homogeneous than the income from work in younger groups. Moreover, the current paper seeks to situate Theil’s approach in the context of scholarly writings since 1967.     

A new route to functionalized 3‐aminopyridazines by ANRORC type ring transformation of 1,2,4‐triazines with carbon nucleophiles

The reaction of 3‐chloro‐6‐phenyl‐1,2,4‐triazine 1a with carbon nucleophiles 2a? d bearing a cyano substituent at a carbanionic center has been studied. In all reactions the formation of the corresponding 3‐aminopyridazines 3a? d takes place via ANRORC mechanism involving addition of the nucleophile at position 5 in compound 1a , ring opening with breaking of the N₄? C₅ bond and intramolecular ring closure of the resulting open‐chain intermediate. A ¹⁵N study with labeled phenylacetonitrile 2a* has shown that the nitrogen atom of the exocyclic amino group of 3‐amino‐4,6‐diphenylpyridazine 3a was originally present in phenylacetonitrile.     

Synthesis of silylene–propenylene oligomers via catalytic polycondensation of diallyldiorganosilanes

Acyclic diene polycondensation (ADP) of diallyldiorganosilanes (CH₂CHCH₂)₂SiR₂ (where R = Me, Ph), in the presence of various ruthenium and rhodium complexes, led predominantly to linear silylene–propenylene oligomers. Ruthenium catalysts (e.g. RuCl₂(PPh₃)₃, RuHCl(CO)(PPh₃)₃, and RuCl(SiMe₃)(CO)(PPh₃)₂) were found to be more efficient than the rhodium ones. The reaction proceeds via preliminary catalytic isomerization of allylsilane to silyl-1-propenes followed by their oligococondensation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3299–3304, 1997