ABSTRACT
Here we demonstrate resonant random lasing in Rhodamine B-doped polymeric microstructures fabricated by means of femtosecond laser writing via two-photon polymerization. To the best of our knowledge, this is the first demonstration of random lasing action in on-chip microdevices. Their feedback mechanism relies on diffuse reflections at the structure sidewall surfaces, which is known as spatially localized feedback since the scattering centers lie over the edges of the gain medium. By exciting the structures with a pulsed laser at 532 nm, a multimode emission with randomly distributed narrow peaks was observed, in accordance with the random nature of the feedback mechanism. Interestingly, their lasing threshold was found to be on the order of tens of nanojoules, which is comparable to what had been achieved for usual microcavities, thereby demonstrating the potentiality of these devices as solid-state lasers for integrated optics applications.
ABSTRACT
This work investigated the preventive effect of Artemisia annua L. dried leaves supplied as a botanical coccidiostat to two broiler genotypes reared in a Danish free-range system in a factorial experiment (two genotypes and ± supplement of dried A. annua leaves). The genotypes White Bresse L40, a pure slow-growing line, and Kosmos 8 Ross, a hybrid genotype with medium growing characteristics, were used. Broilers were raised indoor until 29-days-old and kept free of parasites. Twelve groups of 30 randomly selected broilers were placed in the range forming three replicates for each treatment combination. The paddocks were cultivated with a mix of grass and clover. A separate group of broilers was naturally infected with Eimeria spp. oocysts and five animals nominated as "seeders" were introduced to the above mentioned 12 groups, 10 days after its formation, with each group consisting of 35 animals per plot. This infection strategy was meant to imitate the transmission pathway observed at farm level. Ten individual birds from each of the 12 groups, in total 120 animals of mixed sex, were monitored twice weekly for 30 days for oocysts excretion. PCR of pooled faecal samples, oocyst morphology and localization upon necropsy were used to identify the Eimeria species involved in the infection. In general, broilers from both genotypes in the range coped well with a coccidia infection caused by Eimeria acervulina and Eimeria maxima as no clinical symptoms, or deaths, were reported during the experiment. In general, broilers supplemented with A. annua dried leaves showed a significantly (p<0.05) reduced number of excreted oocysts during the infection with no interaction to genotype. Females generally had a significantly higher shedding of oocysts than males (p<0.05). The overall body weight gain and the daily weight gain when infection was subdued showed a three-way interaction among genotype, sex and treatment - accounted mainly for the fact that Kosmos females responded positively to the Artemisia treatment while Kosmos males responded negatively, and only minor differences were found between sexes for the White Bresse genotype. In conclusion, supply of A. annua dried leaves as a botanical coccidiostat significantly reduced oocyst output in free ranged broilers and thus may form part of a strategy to prevent commercial losses.
