A simple construction of a physical pendulum and the results of measurements of its period at very large amplitudes (up to 175 • ) are reported. The results are in good agreement with the exact theory.
5-Carboxymethylaminomethyluridine (cmnm 5 U) and 5-carboxymethylaminomethyl-2-thiouridine (cmnm 5 s 2 U) are located at the wobble position in several cytosolic and mitochondrial tRNA sequences. In this paper, we report the first site-selected incorporation of cmnm 5 U and cmnm 5 s 2 U into RNA sequences by phosphoramidite chemistry on a CPG solid support. Trifluoroacetyl and 2-(trimethylsilyl)ethyl were selected for the protection of the amine and carboxyl functions, respectively.
5-Taurinomethyluridine (τm 5 U) and 5-taurinomethyl-2-thiouridine (τm 5 s 2 U) are located at the wobble position of human mitochondrial (hmt) tRNA Leu(UUR) and tRNA Lys , respectively. Both hypermodified units restrict decoding of the third codon letter to A and G. Pathogenic mutations in the genes encoding hmt-tRNA Leu(UUR) and hmt-tRNA Lys are responsible for the loss of the discussed modifications and, as a consequence, for the occurrence of severe mitochondrial dysfunctions (MELAS, MERRF). Synthetic oligoribonucleotides bearing modified nucleosides are a versatile tool for studying mechanisms of genetic message translation and accompanying pathologies at nucleoside resolution. In this paper, we present site-specific chemical incorporation of τm 5 U and τm 5 s 2 U into 17-mers related to the sequence of the anticodon arms hmt-tRNA Leu(UUR) and hmttRNA Lys , respectively employing phosphoramidite chemistry on CPG support. Selected protecting groups for the sulfonic acid (4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutyl) and the exoamine function (-C(O)CF 3 ) are compatible with the blockage of the canonical monomeric units. The synthesis of τm 5 s 2 U-modified RNA fragment was performed under conditions eliminating the formation of side products of 2-thiocarbonyl group oxidation and/or oxidative desulphurization. The structure of the final oligomers was confirmed by mass spectroscopy and enzymatic cleavage data.
In this article the results concerned influence of processing conditions of the wire electrical discharge machining and vibro‐abrasive machining on the surface layer and morphology of samples made of hard machinable materials used in aircraft industry like: Titanium 5553 β, Inconel 617, Hastelloy X and Magnesium AZ31 have been presented. For this purpose the cubic and cylindrical samples made of hard machinable alloys have been prepared using optimal electric parameters of wire‐cut electrical discharge machining and finally they have been polished using circular vibratory finishing technology and different ceramic shaped stones.
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