AB-INITIO INVESTIGATION OF 2D MATERIALS FOR GAS SENSING, ENERGY STORAGE AND SPINTRONIC APPLICATIONS

The field of Two Dimensional (2D) materials has been extensively studied since their discovery in 2004, owing to their remarkable combination of properties. My thesis focuses on exploring novel 2D materials such as Graphene Nanoribbon (GNR), holey carbon nitride C2N, and MXenes for energy storage, gas sensing, and spintronic applications, utilizing state-of-the-art techniques that combine Density Functional Theory (DFT) and Non-Equilibrium Greens Functions (NEGF) formalism; namely Vienna Ab-initio Simulation Package (VASP) and Atomistic Toolkit (ATK) package.Firstly, on the side of gas sensing, the burning of fossil fuels raises the level of toxic gas and contributes to global warming, necessitating the development of highly sensitive gas sensors. To start with, the adsorption and gas-sensing properties of bilaterally edge doped (B/N) GNRs were investigated. The transport properties revealed that the bilateral B/N edge-doping of GNR yielded Negative Differential Resistance (NDR) IV-characteristics, due to the electron back-scattering which was beneficial for selective gas sensing applications. Therefore, both GNR: B/N were found to be good sensors for NO2 and SO3 respectively. After that, the catalytic activity of four magnetic transition metal “TM” elements (e.g., Mn, Fe, Co and Ni) embedded in C2N pores, as Single-Atom Catalysts (SAC), was tested towards detecting toxic oxidizing gases. The results of spin-polarized transport properties revealed that Ni- and Fe-embedded C2N are the most efficient in detecting NO/ NO2 and NO2 molecules.Secondly, on the side of energy storage, since the fossil fuels reserves are depleting at an alarming rate, there is an urgent need for alternative forms of energy to meet the ever-growing demand for energy. Hydrogen is a popular form of clean energy. However, its storage and handling are challenging because of its explosive nature. The effect of magnetic moment on the hydrogen adsorption and gas-sensing properties in Mn-embedded in C2N were investigated. Two distinct configurations of embedment were considered: (i) SAC: 1Mn@C2N; and (ii) DAC: Mn2@C2N. Based on the huge changes in electronic and magnetic properties and the low recovery time (i.e., τ ≪ 1 s, τ = 92 μs and 1.8 ms, respectively), we concluded that C2N:Mn is an excellent candidate for (reusable) hydrogen magnetic gas sensor with high sensitivity and selectivity and rapid recovery time. Then, a comparative study of hydrogen storage capabilities on Metal- catalyst embedded (Ca versus Mn) C2N is presented which demonstrated the stability of these metal structures embedded on the C2N substrate. We proposed Ca@C2N and Mn@C2N for dual applications- hydrogen storage and a novel electrode for prospective metal-ion battery applications owing to its high irreversible uptake capacity 200 mAhg-1.Thirdly, on the side of data storage, spintronics is an emerging field for the next generation nanoelectronics devices to reduce their power consumption and to increase their memory and processing capabilities. Designing 2D-materials that exhibit half-metallic properties is important in spintronic devices that are used in low-power high-density logic circuits. We tested samples comprising of SAC and DAC of Mn embedded in a C2N sample size 2×2 primitive cells as well as their combinations in neighboring large pores. Many other TM catalysts were screened, and the results show the existence of half metallicity in just five cases: (a) C2N:Mn (DAC, SAC-SAC, and SAC-DAC); (b) C2N:Fe (DAC); and (c) C2N:Ni (SAC-DAC). Our results further showed the origins of half-metallicity to be attributed to both FMC and synergetic interactions between the catalysts with the six mirror images, formed by the periodic-boundary conditions.Lastly, on the side of batteries, sodium-sulfur batteries show great potential for storing large amounts of energy due to their ability to undergo a double electron- redox process, as well as the plentiful abundance of sodium and sulfur resources. However, the shuttle effect caused by intermediate sodium polysulfides (Na2Sn) limits their performance and lifespan. To address this issue, we proposed two functionalized MXenes Hf3C2T2 and Zr3C2T2 (T= F, O), as cathode additives to suppress the shuttle effect. We found that both Hf3C2T2 and Zr3C2T2 systems inhibit the shuttle effect by binding to Na2Sn with a binding energy higher than the electrolyte solvents. The decomposition barrier for Na2Sn on the O functionalized MXenes gets reduced which enhances the electrochemical process. Overall, our findings show that the tuning of 2D materials can lead to promising applications in various fields, including energy storage, gas sensing, and spintronics

Is privatisation without effective regulation bad for the poorest?

There is an urgent need of more efficient and effective infrastructure/utility provision, a boost in investment levels from both domestic and foreign sources and an expanded and dynamic private sector in African countries. All of the above can be achieved through privatisation. However, African states have been slow and reluctant privatisers as a result a significant proportion of industrial/manufacturing and most infrastructures still belong to the state Nellis (2005). However, Leftist thinkers have condemned the privatisation of former state-owned services as a sell-out of public goods and as a final victory of market capitalism that has a tendency to make the rich even richer and more affluent and the poor more destitute. As most developing nations are focused on reducing poverty for some privatisation may be the way out. The paper explores how privatisation may reduce or increase poverty levels. The focus of this paper is on African countries. The results of privatisation in Africa are mixed and it is observed that privatisation has not been entirely successful for any of the African countries.[1] This paper attempts to analyse whether privatisation without effective regulation is bad for the poorest in society and illustrates the case of privatisation in Guinea and Senegal. Keywords: Privatisation, Africa, Poverty Reduction, Regulation [1] http://www.ascleiden.nl/content/webdossiers/privatization-afric

Literacy teachers' enactment of critical pedagogies with multicultural children's literature during interactive read aloud

This qualitative, multi-case study examines the classroom interactions between three critical elementary teachers and their students during interactive read-aloud events with multicultural children’s literature. For one school year, I observed and video- and audio- recorded these teachers’ read-alouds and literature discussions in order to consider the following three research questions: 1. How do elementary literacy teachers sustain and grow their enactment of critical pedagogies? 2. During whole-group discussions of multicultural children’s literature, how do teachers address critical sociocultural knowledge and issues of inequity? 3. How do teachers who practice critical pedagogy navigate the critical encounters that arise when they discuss multicultural children’s literature? Drawing on Freire’s (1970/2000) theory of critical literacy, Kumashiro’s (2001; 2009) theory of anti-oppressive education, and Brown’s (2013) theory of humanizing critical sociocultural knowledge, my analysis centered on illuminating the ways that Ms. Smith, Ms. Barker, and Ms. Martinez enacted critical pedagogies within this structure of literacy instruction, as well as gaining insight into how these teachers sustained and grew their work as critical educators. I took an ethnographic approach to data collection; and I used qualitative and discourse analytic methods to analyze within and across multiple data sources, including audio- and video-recordings, transcriptions, classroom artifacts (e.g., students’ reader responses, photos of language charts), memos, and field notes. In response to my first research question, I report that these teachers sustained and grew their enactment of critical pedagogies by designing an all-encompassing curriculum of experiences for themselves (Brown, 2013) in both their professional and personal lives, engaging in [social justice] praxis, and pursuing opportunities to learn new critical sociocultural knowledge. In response to my second and third research questions, I report that teachers address critical sociocultural knowledge and navigate critical encounters with their students by: a) reimagining the possibilities of interactive read aloud in the elementary classroom; b) extending talk towards criticality; c) turning discourse back to the students. These three cases demonstrate that teachers can offer rich literacy instruction, as well as intentional, daily space to collaboratively build humanizing critical sociocultural knowledge towards transformation.Curriculum and Instructio

Patterns of eeg(electroencephalogram) findings in patients with neurological disorders

OBJECTIVE: To study the patterns of EEG in patients with neurological disorders BACKGROUND: EEG is still relevant in the diagnosis and management of patients with seizure disorders and extends to other neurological conditions, however local data is limite

Osteomalacia in a Case of Adult-Onset Bartter Syndrome

Bartter syndrome is a rare heterogeneous disease characterised by a deficiency in sodium and chloride absorption. Gain-of-function mutations in the CASR gene have been described in some patients with Bartter syndrome associated with hypocalcaemia and hypercalciuria. We describe a case of adult-onset Bartter syndrome with hypocalcaemia severe enough to cause osteomalacia

Methanogenic Diversity and Taxonomy in the Gastro Intestinal Tract of Ruminants

To elucidate the microbial dynamics inside rumen of animals of livestock importance and to provide a better ration to them in order to control various metabolic disorders, a better understanding of the rumen microbial ecology is pivotal. The fundamental knowledge of methanogenic population inside gut environment and ruminal fermentation is of considerable importance as it has a significant impact on the various metabolic activities of the animal. The major methanogens isolated and characterized from ruminants like cattle, sheep, steers, goats, reindeers are from the order Methanobacteriales, Methanomicrobiales, Methanococcales, Methanosarcinales and Methanomassiliicoccales. The chapter deals with present knowledge available regarding the methanogenic diversity present in the gastro-intestinal tract of ruminants all over the world primarily through constructing 16S rRNA gene clone libraries and tries to uncover the new genera in ruminant’s microbiome and their adaptations in extreme environment. To get a better idea regarding the composition of methanogen community, further studies are required in relation to the effect of diet and animal species to the rumen methanogens

Role of habit behaviours in severity of Oral lichen planus, Oral submucous fibrosis and Leukoplakia: A cross sectional study

Background: Smoking, drinking and chewing tobacco product, common habits in India have been positively associated with oral lesions such as oral submucous fibrosis (OSMF), Leukoplakia, and oral lichen planus (OLP). Materials and methods: A total of 160 patients of both genders with age above 35-60 year were divided into four groups of Leukoplakia, OSMF, OLP and control group each. Detailed case history, habit history, habit score was recorded. Results: In this study it was found that OSMF patients with combined habit of smoking tobacco with quid usage patterns, Leukoplakia patients with smoking(beedi) and OLP patients with combined tobacco usage habits and quid usage habits showed presence of advance stages of disease. Conclusion: This study emphasised that deleterious habits as not only a predisposing factor in the occurrence but plays crucial role in progression to severe form of OSMF and Leukoplakia