Maths Express au carrefour des cultures

International audienceCette brochure a été réalisée à l'occasion de la quinzième édition du Salon Culture et Jeux mathématiques. Elle a pour objectif de montrer que les mathématiques sont au coeur de toutes les activités humaines qu'elles soient sociales, techniques, scientifiques, artistiques ou ludiques. Elles sont nées et se sont développées au rythme des sociétés humaines

Stereospecific syntheses of 1-[2,3-dideoxy-3-(<i>N</i>-hydroxy-<i>N</i>-methylamino)-α-D-and α-L-<i>erythro</i>-pentofuranosyl]thymine from L-and D-glutamic acids respectively

Conjugate addition of N-methylhydroxylamine upon (S)-4-(tert-butyldimethylsilyloxymethyl)butenolide 5 proceeded stereospecifically to afford the D-erythro isomer 6. A stereospecific phenylselenylation α to the carbonyl group led to the D-arabino isomer 12, allowing the stereoselective synthesis from L-glutamic acid of the α-D isomer 16 of the title compounds. Conversely, the α-L isomer 16' was obtained from D-glutamic acid. Upon skipping the orientating phenyselenylation step, both α-D-erythro (16) and β-D-erythro (18) isomers were obtained. Contrasting with the significant anti-HIV activity of the β-D-threo isomer, the β-D-erythro nucleoside exhibited no such property but did exhibit anti-VZV activity. On the other hand, the α-D-erythro isomer (16) was devoid of any tested (HIV, HSV, VZV, CMV) antiviral activity and the α-L-isomer 16' was inactive against HIV

Synthesis, antiviral and antiproliferative activity of nucleoside-3'-<i>C</i>-acetamides and nucleoside-3'-<i>C</i>-acetamide oximes

Reduction of 3'-deoxy-3'-methoxycarbonylmethylene or 3'-cyanomethylene-3'-deoxynucleosides followed by ammonolysis or hydroxyaminolysis led respectively to the corresponding nucleoside-3'-C-acetamides or nucleoside-3'-C-acetamide oximes. Some of these novel nucleosides exhibited antiviral or antiproliferative activity

Behavior of ice in the brittle range - a review

Brittle fracture of ice is the central and controlling phenomena in ice mechanics. Load prediction must include ice fracture mechanics and an understanding of the non-stationary nature of the roughness of the contact surface between ice and any structure.NRC publication: Ye