Kristallstruktur von Trimethylisocyanursäure, (CH3NCO)3, und von Trichlorisocyanursäure-1/2-Ethylenchlorid, (ClNCO)3·1/2C2H4Cl2

X-ray crystal structure analyses of (CH₃NCO)₃ (M) and (ClNCO)₃·1/2C₂H₄Cl₂ (C) were carried out at room temperature (MoK, graphite monochromator, =0.71069 Å): 1.M=171.16, monochlinic, P2₁/c,a=14.848 (1) Å,b=13.400 (2) Å,c=8.149 (1) Å, =100.87 (1)°,V=1 592.3 ų,Z=8,F(000)=720,d _x =1.428 Mgm^–3, =76m^–1,R=6.51%,R _w =7.01% (964 reflections, 218 parameters). 2.M=281.89, monochlinic, P 2₁/c,a=9.416 (3) Å,b=5.728 (1) Å,c=18.199 (8) Å, =98.64 (2)°,V=970.4 Å₃,Z=4,F(000)=556,d _x =1.929 Mgm^–3, =1.11 mm^–1,R=3.96%,R _w =3.44% (605 reflections, 132 parameters). The ring systems together with the C atoms of the methyl groups in (M) and with the Cl atoms in (C) are planar and have D_3h-symmetry. Bond lengths and bond angles are discussed with regard to¹⁴N-NQR,³⁵Cl-NQR and vibrational spectroscopic data.

     

Synthesen von 5-Alkyl-2-aryl-pyrimidin-4(3H)-onen

The title substances with R²=H (type1) were synthesized by reductive desulfurization of corresponding 2-aryl-thieno-[2,3-d]pyrimidin-3(3H)-ones and 2-aryl-[1]benzothieno[2,3-d]-pyrimidin-4(3H)-ones (both:A), those with R²=CH₃ (type2) by cyclization of -alkyl-acetoacetates with benzamidines. Some derivatives of1 and2 were also prepared (type3). In some cases Raney-Ni desulfurization ofA gave 2-cyclohexylproducts (type4).

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Teilweise unter Mitarbeit vonMorteza Baradar.     

Quality system implementation in a Brazilian university laboratory

The introduction of quality systems in laboratories at universities is a difficult task. Test services for external customers are provided to generate additional budget, and there may be a clear awareness about the need for systematic QA/QC actions. However, offering services is not of the highest priority within most university environments. The staff performance is commonly evaluated on basis of published papers and teaching activities, giving little or no weight for the test services. Therefore, implementation of a quality system is often pushed back to a lower priority leading to postponement. The efforts for creating a quality system in a laboratory from a Brazilian university are described in this paper, along with the results produced.     

Recycling of isotopically modified molybdenum from irradiated CerMet nuclear fuel: part 4—technetium separation from concentrated molybdate solution

Uranium-free molybdenum-based CerMet fuels can be applied for transmutation of minor actinides in GEN IV reactors or ADS. In a reprocessing concept designed in the first paper in this mini-series (Mareš and John in J Radioanal Nucl Chem 320(1):227–233, 2019. https://doi.org/10.1007/s10967-019-06456-2) the residual radionuclidic impurities need to be separated from slightly alkaline (pH 9.1) highly concentrated ammonium molybdate solutions. Screening tests of technetium extraction onto three extraction chromatographic materials were performed in present study. Solid extractants based on Aliquat^® 336 turned out to be the most promising for Tc extraction from molybdenum solutions both from the point of view of the extraction kinetics and the practical extraction capacity. The overall results of this mini-series allowed to conclude that if the molybdenum recycling concept proposed is adopted, separation of the residual radionuclidic impurities should not represent a significant problem.

     

Toxins as Tools in Neurochemistry

Neurotoxins have evolved as molecules targeted specifically against molecules with an important function in the nervous system. Because of their selectivity they have been used as probes for detecting and characterizing key proteins of the nerve cell. Ion channels involved in the propagation of the action potential, proteins of presynaptic neurotransmitter exocytosis, and most importantly, neurotransmitter receptors have been and are presently being analyzed, in some cases already at atomic level by a combination of the tools of neurotoxins, molecular biology, and patch clamp electrophysiology. In this review a selection of these toxins is presented, together with their targets in the nervous system. Special emphasis is given to the recent breakthroughs in our understanding of the mechanism of action of tetanus and botulinum toxins and to the neurotoxins ranging from the plant alkaloid strychnine to the peptide toxins from poisonous snakes, which were fundamental in elucidating ligand-gated ion channels like the glycine and nicotinic acetylcholine receptors.