The use of rapid prototyping (RP) technology for rapid tooling and rapid manufacturing has given rise to the development of application-oriented composites. The present paper furnishes succinct notes of the composites formed using main rapid prototyping processes such as Selective Laser Sintering/Melting, Laser Engineered Net Shaping, Laminated Object Manufacturing, Stereolithography, Fused Deposition Modeling, Three Dimensional Printing and Ultrasonic Consolidation. The emphasis of the present work is on the methodology of composite formation and the reporting of various materials used.
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Considering the undesirable metabolic stability of our recently identified NNRTI <b>5</b> (<i>t</i><sub>1/2</sub> = 96 min) in human liver microsomes, we directed our efforts to improve its metabolic stability by introducing a new favorable hydroxymethyl side chain to the C-5 position of pyrimidine. This strategy provided a series of novel methylol-biphenyl-diarylpyrimidines with excellent anti-HIV-1 activity. The best compound <b>9g</b> was endowed with remarkably improved metabolic stability in human liver microsomes (<i>t</i><sub>1/2</sub> = 2754 min), which was about 29-fold longer than that of <b>5</b> (<i>t</i><sub>1/2</sub> = 96 min). This compound conferred picomolar inhibition of WT HIV-1 (EC<sub>50</sub> = 0.9 nmol/L) and low nanomolar activity against five clinically drug-resistant mutant strains. It maintained particularly low cytotoxicity (CC<sub>50</sub> = 264 μmol/L) and good selectivity (SI = 256,438). Molecular docking studies revealed that compound <b>9g</b> exhibited a more stable conformation than <b>5</b> due to the newly constructed hydrogen bond of the hydroxymethyl group with E138. Also, compound <b>9g</b> was characterized by good safety profiles. It displayed no apparent inhibition of CYP enzymes and hERG. The acute toxicity assay did not cause death and pathological damage in mice at a single dose of 2 g/kg. These findings paved the way for the discovery and development of new-generation anti-HIV-1 drugs.
In the frame of an ESA contract aiming at the feasibility study of a compact, very stable, optically pumped cesium beam clock for Galileo, we have completed our previous analysis of the frequency stability of such a frequency reference. This analysis concerns the single optical frequency configuration. All possible noise sources are considered. Optimum operating conditions providing the best frequency stability are defined and presented It is shown, and justified by simple arguments, that a resonator using a microwave cavity with a phase difference phi = pi between the two oscillatory fields may either provide a better frequency stability than a cavity of the same length but with phi= 0, or provide a given frequency stability with a cesium consumption significantly lower than in the phi=0 configuration. The analysis is applied to the OSCAR resonator conceived and operated at Observatoire de Neuchatel, with two different operating conditions that provide very high performances: the theoretical and experimental results are in excellent agreement. It is concluded that the presented analysis can be safely used to design very high performance, compact, optically pumped cesium beam clocks.
Abstract C-acyclic nucleoside analogues of inosine and guanosine 8-[(RS)-2,3-dihydroxypropyl] imidazo [1,5-a]-1,3,5-triazin-4 (3H)-ones 6a, c, d were synthesized. The route involved the cyclization-rearrangement of 5-acylamino-5-allyl-6-amino-4,5-dihydropyrimidin-4-ones 4a-c to 8-allylimidazo [1,5-a]-1,3,5-triazin-4 (3H) ones 5a-c. 5a was transformed selectively into 5d by reductive desulfurization with highly deactivated Raney nickel. The poorly soluble compounds 5b and 5c were converted to N-2-acetylated 5f and 5g. Osmium tetroxide hydroxylation of 5d, f, g gave 6a, c, d. None of the newly synthesized C-acyclic nucleoside derivatives showed an appreciable antiviral or antitumor cell activity.
