RESUMO
Experimental evidence is presented that pulsed laser generated ultrasound can reduce the power necessary to phase convert a nm-scale amorphous film into the crystalline phase. The amount of energy carried by pulsed ultrasound is scant when compared to the CW laser power used to crystallize but the effect is substantial. The evidence points to the extra-ordinary effects possible when a small energy perturbation is applied at a critical juncture in dynamical systems. The candidate system is MoS2 (10 nm) sputtered on yttrium-stabilized zirconia single crystal substrate. A focused CW laser elevates the film - initially in a metastable disordered phase - to the order-disorder conversion (crystallization) temperature. Approximately 25 spot sizes removed from the heating source is a second, high repetition rate laser that induces ultrasonic excitation within the film/substrate via thermoelastic action. The processing is done on a moving stage with direct write patterning control. High resolution ex situ Raman spectroscopy, optical profilometry, and TEM are used to characterize the converted material. For this experimental configuration, we measure a 10% reduction in the heating power required to initiate crystalline formation. The measured phenomenon cannot be attributed to excess thermal energy supplied by the ultrasonic laser.
RESUMO
Two experiments were conducted to investigate the effects of timing of prostaglandin F2(alpha) (PGF2(alpha)) administration, controlled internal drug release device (CIDR) removal and second gonodotropin releasing hormone (GnRH) administration on the pregnancy outcome in CIDR-based synchronization protocols. In Experiment 1, suckled Angus crossbred beef cows (n = 580) were given 100 microg of GnRH+a CIDR on Day 0. Cows in Group 1 (modified Ovsynch-P) received 25 mg of dinoprost (PGF2(alpha)) and CIDR device removal on Day 8 (AM), 100 microg of GnRH 36 h later on Day 9 (p.m.), and fixed-time AI (FTAI) 16 h later on Day 10 (47.5+/-1.1 h after PGF2(alpha)). Cows in Group 2 (Ovsynch-P) received 25mg of PGF2(alpha) and CIDR device removal on Day 7 (p.m.), 100 microg of GnRH 48 h later on Day 9 and FTAI 16 h later on Day 10 (66.6+/-1.2 h after PGF2(alpha)). Pregnancy rates were 56.5% (170/301) for Group 1 and 55.6% (155/279) for Group 2, respectively (P = 0.47). In Experiment 2, beef cows (n=734) were synchronized with 100 microg of GnRH+CIDR on Day 0, 25 mg of PGF2(alpha) and CIDR device removal on Day 7 and either 100 microg of GnRH 48 h later on Day 9 (Ovsynch-P) and FTAI 16 h later on Day 10 (64.9+/-3.3 h from PGF2(alpha)) or 100 microg of GnRH on Day 10 (CO-Synch-P) at the time of AI (63.2+/-4.2 h from PGF2(alpha)). Pregnancy rates were 48.8% (180/369) for Ovsynch-P and 44.7% (163/365) for CO-synch-P groups, respectively (P = 0.11). In both experiments, there was a locationxtreatment interaction (P<0.05); pregnancy rates between locations were different (P < 0.05) in the Ovsynch-P group. In conclusion, in a CIDR-based Ovsynch synchronization protocol, delaying administration of prostaglandin and CIDR removal by 12 h, or timing of the second GnRH by 16 h, did not affect pregnancy rates to FTAI. Therefore, there may be an opportunity to make changes in synchronization protocols with out adversely affecting FTAI pregnancy rates.