We report for the first time a new application of four different morphologies including nanonoodles of zinc oxide as a laser ablation micro-thruster. Nano-noodles represent a unique class of materials in which the electrons are confined near the surface owing to the majority of the near surface atoms. The synthesized samples of ZnO were of single phase, having a wurtzite hexagonal structure. Three different morphologies, viz. initial (nanoparticles), intermediate (nano-noodles) and final (complete nano-noodles) of zinc oxide were ablated using a Nd : YAG laser operating at 1064 nm for the measurement of propulsion parameters. The momentum coupling coefficient (C m ) and the specific impulse (I sp ) were evaluated using the non-contact optical triangulation method. It has been observed that the morphology of the material affects the laser ablation propulsion (LAP) parameters. For each sample, the laser fluence for the optimum coupling coefficient owing to the plasma shielding effect has also been found. The synthesized nanostructured zinc oxide samples have been found useful as efficient laser propellants that can be used in a variety of applications due to diversity in their momentum coupling coefficient and specific impulse values.
Purpose
Virtual anatomy education was the only way that supported the learning process of the students during the forced lockdown time of COVID-19 pandemic. The intention of the current study was to apprehend the expected challenges experienced by the medical and dental students during their cyber anatomy classes.
Methods
This study was carried on 300 1st and 2nd year medical and dental students who joined their respective college in January 2020, and consented to participate in the study. A multiple choice questionnaire regarding their stance about these online classes was formed and student’s feedback was taken.
Results
Most (80%) of the students longed for their traditional anatomy learning i.e., dissection courses, didactic lectures, interaction and motivation from their mentors and peer. The students blamed the learning without live dissections, models and microscopic slides for their lack of confidence. More than 80% students blamed inappropriate gadgets, absence of high-band internet connections, as possible barriers in their digital learning. Lack of self-motivation was considered by 66% students.
Conclusions
This situation of anatomy education while lockdown was not intentional and should not be taken as the silver bullet solution for a subject like anatomy. Although students had to face a lot of challenges but this shift to online mode went swiftly at the time of health crisis. This digital learning may extend for an indefinite period, the students’ feedback will be helpful in bringing appropriate and timely modifications in digital anatomy education.
Ablative laser propulsion (ALP) is a type of beam-powered propulsion in which thrust is produced by ablating a target using a high-intensity laser beam. In this research work, we calculated the ALP parameters momentum coupling coefficient (Cm) and specific impulse (Isp) by confining the plasma with the help of external semi-elliptical cavities. The cavity minor axis was fixed at 2.5mm while the major axis varied to 7mm, 9mm, 11mm, 13mm and 15mm. Silver and aluminum samples were used as propellants. A pulsed Q-smart Nd: YAG laser operating at 532nm wavelength was used to ablate the target. A significant increase in the value of Cm and Isp was observed using confined ablative propulsion. The highest Cm and Isp were recorded for the 9 mm major axis cavity, for which Cm was increased from 5.01x10-5 N-s/J to1.75x10-4 nearly 249% for silver and from 3.4x10-5 N-s/J to 8.9x10-5 N-s/J nearly 161% for aluminum. Hence the use of semielliptical cavities is an effective technique for enhancing propulsion parameters. Cavity acts as a trap for plasma and shockwaves. Confinement of plasma and reflection of shockwaves from the cavity walls results in enhanced laser ablation propulsion parameters.
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