Closed Shell Atoms subjected to Short and Intense Laser Pulses

This thesis contains several theoretical investigations of different ionization phenomena resulting from exposure of closed-shell atoms and atomic species to short and intense laser pulses. 1. Wigner time delay in atomic photoionization of noble gas atoms. Theory is based on a perturbative treatment of the interaction of an atom with a weak ionizing electromagnetic field. Inter-electron interaction is treated non perturbatively by the random phase approximation with exchange (RPAE) [Phys. Rev. A 98, 013420 (2018)]. 2. Atomic time delay in free and encapsulated noble gas atoms atoms subjected to XUV ionizing and IR dressing fields (RABBITT). Strong laser-atom interaction is treated non-perturbatively by a numerical solution of the time dependent Schrodinger equation (TDSE). Many-electron correlations are omitted and the atom is considered in the single active electron (SAE) approximation [Phys. Rev. A 97, 063404 (2018), Phys. Rev. A 98, 043427 (2018)]. 3. High order harmonics generation in noble gases and transitional atoms near giant autoionization resonances. The tunnel ionization and laser driven propagation is described by the SAE TDSE in while recombination with the parent ion is affected by inter-shell many-electron correlation which is accounted for in the RPAE [Phys. Rev. A 101, 053415 (2020)] or spin-polarized RPAE [Phys. Rev. A 101, 053415 (2020)]. The main theoretical tools employed in this thesis are TDSE for treating laser atom interaction in SAE and RPAE for treating laser-matter interaction perturbatively while keeping the full account of inter-electron interaction. These techniques are used in separation as in 1 and 2 or collectively as in 3. The TDSE and RPAE which are common themes of this thesis are described in the Introduction. They are implemented within efficient computer codes deployed in multi-processor supercomputer environment. Our numerical results reveal important aspects of ultrafast electron dynamics in atomic ionization and will serve to guide the existing and future strong laser physics experiments

Simulation of angular-resolved RABBITT measurements in noble-gas atoms

We simulate angular-resolved RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) measurements on valence shells of noble-gas atoms (Ne, Ar, Kr, and Xe). Our nonperturbative numerical simulation is based on solution of the time-dependent Schrödinger equation (TDSE) for a target atom driven by an ionizing XUV and dressing IR fields. From these simulations we extract the angular-dependent magnitude and phase of the RABBITT oscillations and deduce the corresponding angular anisotropy β parameter and Wigner time delay τ W for the single XUV photon absorption that initiates the RABBITT process. Said β and τ W parameters are compared with calculations in the random-phase approximation with exchange (RPAE), which includes intershell correlation. This comparison is used to test various effective potentials employed in the one-electron TDSE. In lighter atoms (Ne and Ar), several effective potentials are found to provide accurate simulations of RABBITT measurements for a wide range of photon energies up to 100 eV above the valence-shell threshold. In heavier atoms (Kr and Xe), the onset of strong correlation with the d shell restricts the validity of the single active electron approximation to several tens of eV above the valence-shell threshold

Mitigating Salt-Induced Damages in Wheat with Foliar-Applied Nigella sativa Seed Extract: A Comprehensive Study

Nigella sativa, a medicinal plant, known for its diverse bioactive compounds, including antioxidants and phytohormones, have shown potential in mitigating salt stress in various plant species. Amongst naturally occurring plant growth stimulants, it has attained enormous attention being rich in thymoquinineand carvacrol in seeds for scavenging free radicals. This research aimed to investigate the effect of Nigella sativa seed extract (NSE) as foliar spray (0, 50, 100 and 150g seeds per liter each) on wheat growth under salt stress (0mM, 75mM and 150mM). Results revealed that salinity decreased growth attributes and accumulation of photosynthetic pigments. On the other hand, salinity stress boosted the contents of malondialdehyde, hydrogen peroxide, glycinebetaine, leaf free proline, Na+ and Cl-. Foliar application of NSEameliorated the negative effects of salinity to considerable extent by enhancing growth traits, chlorophyll contents, glycinebetaine and prolineand decreased Na+, Cl-,malondialdehyde andhydrogen peroxide. This research provides valuable insights into the potential use of NSE as natural and sustainable solution to alleviate salt stress in wheat crop. These findings contribute to the development of eco-friendly strategies for enhancing crop resilience in saline environments, ultimately addressing the global challenge of food security in the face of increasing soil salinity

Intershell-correlation-induced time delay in atomic photoionization

We predict an observable Wigner time delay in outer atomic shell photoionization near inner shell thresholds. The near-threshold increase of time delay is caused by intershell correlation and serves as a sensitive probe of this effect. The time delay increase is present even when the inner and outer shell thresholds are hundreds of electron volts apart. We illustrate this observation by several prototypical examples in noble gas atoms from Ne to Kr. In our study, we employ the random phase approximation with exchange and its relativistic generalization. We also support our findings by a simplified, yet quite insightful, treatment within the lowest-order perturbation theory.S.T.M. acknowledges the support of the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy, under Grant No. DE-FG02-03ER15428

Happiness, Gratitude, Life Satisfaction, and Life Orientation among Working and Non-working Individuals

The study was conducted to find differences among working and non-working individuals regarding happiness, gratitude, life satisfaction, and life orientation. Convenient sampling technique was used to collect the data. The sample consisted of 300 individuals; 150 were working and 150 were non-working individuals. Out of 150 working participants, 75 participants were bankers and 75 were teachers. The non-working sample consisted of 75 males and 75 females. Oxford Happiness Questionnaire, The Gratitude Questionnaire-six item form (GQ- 6), Satisfaction with Life Scale and Life Orientation Test-Revised were used to measure happiness, gratitude, life satisfaction, and life orientation respectively. Correlation unveiled that happiness, gratitude, life satisfaction, and life orientation were positively correlated. Independent sample t-test showed that working individuals were happier, more grateful, and more satisfied with life as compared to non-working individuals while non-working females showed higher levels of gratitude, satisfaction, and positive life orientation than non-working men. Further independent sample t test indicated that bankers were happier than teachers. Multiple regression analysis showed that happiness and gratitude predict life satisfaction

Black Tea: Chemical and Pharmacological Appraisal

Medicinal plants are gaining popularity as folk medicine due to future demand to get rid of synthetic health promoting medicines. Nowadays, black tea is gaining interest as the most frequently consumed therapeutic drink after the water. The importance of black tea is due to existence of flavonoids such as (Thearubigins (TRs) and theaflavins (TFs) and catechins) that are the main therapeutic agents and are more bio-direct and stable compounds compared to those exist in other herbal plants alongside some other promising compounds which enhance is credentials as therapeutic drug. Numerous scientific explorations have elucidated the biological worth of these bioactive moieties against plethora of ailments with special reference to metabolic disorder. The mandate of current chapter is to discuss the black tea chemistry for elucidating its pharmacological worth

Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial

Background Post-partum haemorrhage is the leading cause of maternal death worldwide. Early administration of tranexamic acid reduces deaths due to bleeding in trauma patients. We aimed to assess the effects of early administration of tranexamic acid on death, hysterectomy, and other relevant outcomes in women with post-partum haemorrhage. Methods In this randomised, double-blind, placebo-controlled trial, we recruited women aged 16 years and older with a clinical diagnosis of post-partum haemorrhage after a vaginal birth or caesarean section from 193 hospitals in 21 countries. We randomly assigned women to receive either 1 g intravenous tranexamic acid or matching placebo in addition to usual care. If bleeding continued after 30 min, or stopped and restarted within 24 h of the first dose, a second dose of 1 g of tranexamic acid or placebo could be given. Patients were assigned by selection of a numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number. Participants, care givers, and those assessing outcomes were masked to allocation. We originally planned to enrol 15 000 women with a composite primary endpoint of death from all-causes or hysterectomy within 42 days of giving birth. However, during the trial it became apparent that the decision to conduct a hysterectomy was often made at the same time as randomisation. Although tranexamic acid could influence the risk of death in these cases, it could not affect the risk of hysterectomy. We therefore increased the sample size from 15 000 to 20 000 women in order to estimate the effect of tranexamic acid on the risk of death from post-partum haemorrhage. All analyses were done on an intention-to-treat basis. This trial is registered with ISRCTN76912190 (Dec 8, 2008); ClinicalTrials.gov, number NCT00872469; and PACTR201007000192283. Findings Between March, 2010, and April, 2016, 20 060 women were enrolled and randomly assigned to receive tranexamic acid (n=10 051) or placebo (n=10 009), of whom 10 036 and 9985, respectively, were included in the analysis. Death due to bleeding was significantly reduced in women given tranexamic acid (155 [1·5%] of 10 036 patients vs 191 [1·9%] of 9985 in the placebo group, risk ratio [RR] 0·81, 95% CI 0·65–1·00; p=0·045), especially in women given treatment within 3 h of giving birth (89 [1·2%] in the tranexamic acid group vs 127 [1·7%] in the placebo group, RR 0·69, 95% CI 0·52–0·91; p=0·008). All other causes of death did not differ significantly by group. Hysterectomy was not reduced with tranexamic acid (358 [3·6%] patients in the tranexamic acid group vs 351 [3·5%] in the placebo group, RR 1·02, 95% CI 0·88–1·07; p=0·84). The composite primary endpoint of death from all causes or hysterectomy was not reduced with tranexamic acid (534 [5·3%] deaths or hysterectomies in the tranexamic acid group vs 546 [5·5%] in the placebo group, RR 0·97, 95% CI 0·87-1·09; p=0·65). Adverse events (including thromboembolic events) did not differ significantly in the tranexamic acid versus placebo group. Interpretation Tranexamic acid reduces death due to bleeding in women with post-partum haemorrhage with no adverse effects. When used as a treatment for postpartum haemorrhage, tranexamic acid should be given as soon as possible after bleeding onset. Funding London School of Hygiene & Tropical Medicine, Pfizer, UK Department of Health, Wellcome Trust, and Bill & Melinda Gates Foundation

Aspects of Homogeneous Heterogeneous Reactions for Nanofluid Flow Over a Riga Surface in the Presence of Viscous Dissipation

The aim of our study is to delineate the characteristics of fluid flow comprising single-wall and multi-wall carbon nanotubes (SWCNTs and MWCNTs) along the surface of a Riga plate fixed in a porous environment. We carried out in-depth comparative analysis to depict the behavior of SWCNTs and MWCNTs when water and kerosene oil are used as base fluids. Homogeneous–heterogeneous reactions generated a significant impact on flow dynamics; furthermore, we also discuss the impact of viscous dissipation. We assembled numerical solutions for non-dimensionalized ordinary differential equations with the help of the shooting technique; moreover, by employing the same procedure, we report the conduct of dominating parameters on velocity, temperature, and concentration profiles. The results show highly desirable skin friction coefficient and Nusselt number values, which we exhibit in terms of tabular data

Aspects of Homogeneous Heterogeneous Reactions for Nanofluid Flow Over a Riga Surface in the Presence of Viscous Dissipation

The aim of our study is to delineate the characteristics of fluid flow comprising single-wall and multi-wall carbon nanotubes (SWCNTs and MWCNTs) along the surface of a Riga plate fixed in a porous environment. We carried out in-depth comparative analysis to depict the behavior of SWCNTs and MWCNTs when water and kerosene oil are used as base fluids. Homogeneous–heterogeneous reactions generated a significant impact on flow dynamics; furthermore, we also discuss the impact of viscous dissipation. We assembled numerical solutions for non-dimensionalized ordinary differential equations with the help of the shooting technique; moreover, by employing the same procedure, we report the conduct of dominating parameters on velocity, temperature, and concentration profiles. The results show highly desirable skin friction coefficient and Nusselt number values, which we exhibit in terms of tabular data

Photoionization of Xe and Xe@ C60 from the 4d shell in RABBITT fields

We consider photoemission from the 4 d shell of the free Xe and encapsulated Xe@ C 60 atoms by ionizing XUV and probing IR fields typical for a RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) measurement