Pressure dependence of laser oscillation and superfluorescent emission from an optically pumped CF4 laser

Experiments on pressure dependence of a CF₄ laser have been carried out to elucidate dynamic characteristics of CF₄ molecules pumped by CO₂ lasers. The results are followed by a model calculation which characterizes collisional quenching of the energy levels related to the stimulated emission. The enhancement of the laser output induced by buffer-gas addition, which was found under specific conditions, is discussed in relation to the competition between laser and superfluorescent emissions.     

Microwave‐Assisted Solid‐Phase Synthesis of Antifreeze Glycopeptides

Microwave‐assisted solid‐phase synthesis allows for the rapid and large‐scale preparation and structure–activity characterization of tandem repeating glycopeptides, namely monodispersed synthetic antifreeze glycopeptides (syAFGPs, H‐[Ala‐Thr(Galβ1,3GalNAcα1→)‐Ala]_n‐OH, n=2–6). By employing novel AFGP analogues, we have demonstrated that of the monodispersed syAFGP_n (n=2–6, degree of polymerization, DP=2–6, M_w=1257–3690 Da), syAFGP₅ (DP=5, M_w=3082 Da) and syAFGP₆ (DP=6, M_w=3690 Da) exhibit the ability to form typical hexagonal bipyramidal ice crystals and satisfactory thermal hysteresis activity. Structural characterization by NMR and CD spectroscopy revealed that syAFGP₆ forms a typical poly‐L ‐proline type II helix‐like structure in aqueous solution whereas enzymatic modification by sialic acid of the residues at the C‐3 positions of the nonreducing Gal residues disturbs this conformation and eliminates the antifreeze activity.     

A simple optical device for generating square flat-top intensity irradiation from a gaussian laser beam

A simple optical device, by which a square flat-top intensity irradiation area can be produced from a laser beam having a gaussian profile, is developed. Calculated nonuniformity [(I_max-I_min)/(I_max+I_min)×100] and the efficiency of this optical device (total energy irradiated in the square region/total energy of the gaussian beam) were 3% and 94%, respectively, for the best irradiation condition.