Hanan Hassan Fouad

As the demand for a quick and remote way of hardness estimation increases, the attention to use LIBS for such application increases. Most of the studies of hardness estimation that have been done used nanosecond laser sources for LIBS while using femtosecond laser has not been studied yet. In this work, a group of five samples with different hardness were analyzed using nanosecond and femtosecond LIBS for relative hardness estimation. Almost the same wavelength was used to decrease the effect of wavelength as much as possible. Considering that the laser produced plasma is in a state of local thermodynamic equilibrium (LTE), the Boltzmann plot method was adopted to calculate the plasma excitation temperature (Te) which is closely correlated to the samples’ hardness. It was found that in case of nanosecond LIBS as the sample hardness increases the excitation temperature Te increases, while for the femtosecond LIBS the behavior was opposite and Te was found to be decreasing as the hardness of the target increases. This result may be attributed to the different plasma plume creation processes and its expansion for both nano- and femto- second lasers.

Maternal metabolic disorders may cause lipotoxic effects on the developing oocyte. Understanding the timing at which this might disrupt embryo epigenetic programming and how this is linked with mitochondrial dysfunction is crucial for improving assisted reproductive treatments, but has not been investigated before. Therefore, we used a bovine in vitro model to investigate if pathophysiological palmitic acid (PA) concentrations during in vitro oocyte maturation and in vitro embryo culture alter embryo epigenetic patterns (DNA methylation (5mC) and histone acetylation/methylation (H3K9ac/H3K9me2)) compared to control (CONT) and solvent control (SCONT), at the zygote and morula stage. Secondly, we investigated if these epigenetic alterations are associated with mitochondrial dysfunction and changes in ATP production rate, or altered expression of epigenetic regulatory genes. Compared to SCONT, H3K9ac and H3K9me2 levels were increased in PA-derived zygotes. Also, 5mC and H3K9me2 levels were increased in PA-exposed morulae compared to SCONT. This was associated with complete inhibition of glycolytic ATP production in oocytes, increased mitochondrial membrane potential and complete inhibition of glycolytic ATP production in 4-cell embryos and reduced SOD2 expression in PA-exposed zygotes and morulae. For the first time, epigenetic alterations in metabolically compromised zygotes and morulae have been observed in parallel with mitochondrial dysfunction in the same study.