First-principles modelling of functional perovskites

The perovskite structure is common to a wide range of materials which exhibit a rich variety of physical properties, such as ferroelectricity, antiferromagnetism, piezoelectricity, giant magnetoresistance, etc. along with different types of phase transition (metal-insulator, magnetic, ferroelectric and structural transitions). The control of the physical properties of perovskites by varying temperature, pressure, composition, and external fields give rise to novel phases. With continued advances in computational power, algorithms and simulation techniques, computational research has become increasingly effective in understanding and complementing experiments. In particular, density functional theory (DFT) based simulations provide fundamental insights into structural stability and properties of a material under the influence of external stimuli. On the other hand, classical and quantum atomistic modelling of materials helps in the study of their properties at long length and time scales by using molecular dynamics. In this thesis, I use DFT and ab initio molecular dynamics (AIMD) to model functional perovskites. This thesis deals with various types of perovskites based on the kind of atomic/molecular species constituting the perovskite structure and explains the complex interplay between structure and properties in these materials. Starting with an inorganic multiferroic perovskite, BiFeO3, the effect of cobalt doping in BiFeO3 on its structural, electronic, ferroelectric and thermodynamic properties is explored, in the context of potential photocatalytic applications. I present an AIMD investigation of the structural, electronic, vibrational and thermodynamic properties of mixed-cation mixed-anion perovskite solid solution of FAPbI3 and MAPbBr3 for photovoltaic applications. Finally, I study molecular perovskites and the phase transitions observed in them, which can be employed for solid-state refrigeration applications based on the barocaloric effect. The effect of different metal cations on the mechanical properties is calculated, which provides a starting point for rational design of molecular perovskites with strong barocaloric behaviour. This work illustrates the rich diversity in behaviour of perovskite-based materials and how first principles simulations can make substantial contributions to understanding and controlling their functional properties

Obesity and women health: from womb to tomb

Obesity is a highly prevalent disease reaching epidemic proportions these days in India. Obesity affects all human beings especially women affecting their health drastically. It affects each phase of their life in serious manner. We present here the spectrum of diseases that obesity can cause to a women during her entire life

Tilt and shift polymorphism in molecular perovskites

Molecular perovskites, i.e. ABX3 coordination polymers with a perovskite structure, are a chemically diverse material platform for studying fundamental and applied materials properties such as barocalorics and improper ferroelectrics. Compared to inorganic perovskites, the use of molecular ions on the A- and X-site of molecular perovskites leads to new geometric and structural degrees of freedom. In this work we introduce the concept of tilt and shift polymorphism, categorising irreversible perovskite-to-perovskite phase transitions in molecular perovskites. As a model example we study the new molecular perovskite series [(nPr)3(CH3)N]M(C2N3)3 with M = Mn2+, Co2+, Ni2+, and nPr = n-propyl, where different polymorphs crystallise in the perovskite structure but with different tilt systems depending on the synthetic conditions. Tilt and shift polymorphism is a direct ramification of the use of molecular building units in molecular perovskites and as such is unknown for inorganic perovskites. Given the role of polymorphism in materials science, medicine and mineralogy, and more generally the relation between physicochemical properties and structure, the concept introduced herein represents an important step in classifying the crystal chemistry of molecular perovskites and in maturing the field

India’s Growing Trade Relationship within South Asia: Reflections from Trends of the Recent Past

India is a crucial player in South Asia; its trade with neighbouring countries is the major driver of growth in the region. The study examines the role of India in expanding trade relations within the South Asian region. The goal of this study is to investigate how India’s individual relations with other countries of the South Asian Association for Regional Cooperation can enhance growth of the region. The focus is on exports, imports, trade balance, and major goods exchanged between India and individual countries, based on the latest data (2013-19). The study then analyses the hurdles that India faces in expanding trade. The discussion further dwells into potential areas wherein opportunities can be created to enhance the trade. The study concludes with a comparison between the South Asian Free Trade Agreement (SAFTA) and the ASEAN Free Trade Agreement (AFTA), focusing on how the former can draw lessons from the latter

The Alternaria alternata Mycotoxin Alternariol Suppresses Lipopolysaccharide-Induced Inflammation

The Alternaria mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) have been shown to possess genotoxic and cytotoxic properties. In this study, the ability of AOH and AME to modulate innate immunity in the human bronchial epithelial cell line (BEAS-2B) and mouse macrophage cell line (RAW264.7) were investigated. During these studies, it was discovered that AOH and to a lesser extent AME potently suppressed lipopolysaccharide (LPS)-induced innate immune responses in a dose-dependent manner. Treatment of BEAS-2B cells with AOH resulted in morphological changes including a detached pattern of growth as well as elongated arms. AOH/AME-related immune suppression and morphological changes were linked to the ability of these mycotoxins to cause cell cycle arrest at the G2/M phase. This model was also used to investigate the AOH/AME mechanism of immune suppression in relation to aryl hydrocarbon receptor (AhR). AhR was not found to be important for the immunosuppressive properties of AOH/AME, but appeared important for the low levels of cell death observed in BEAS-2B cells

One glasses too many: A case report of Benson′s syndrome

We report a case of Benson′s Syndrome, a form of occipital Alzheimer′s disease, with posterior cortical atrophy on magnetic resonance imaging, in a 62-year-old male, who presented with visual problems, ascribed to the eyes, and had even undergone cataract/intraocular lens surgery in the right eye; and change of glasses 21 times over the past 2 years, with no apparent benefit. This case is of interest both on account of its rarity, and to highlight its features since the diagnosis may be missed in an ophthalmological setting where such patient may go for first consult

ML-Based Device-Agnostic Human Activity Detection with WiFi Sniffer Traffic

Human Activity Detection plays a pivotal role in smoothly managing the health care for the elderly and those with chronic health conditions in smart home environments. Even though there are several technological advancements made in this area, solutions like smartwatches are costly to afford and the solutions that rely on sensors and cameras suffer from privacy concerns. While wireless channel state information-based approaches can address some of these limitations, these approaches either require special hardware to be deployed or modifications at the WiFi access point. In this paper, we propose to detect human activities in a device-agnostic manner by leveraging passively captured passively captured WiFi MAC-layer traffic with the help of a sniffer. In that way, elderly people and those who suffer from chronic health conditions do not need to put any sensors on their body. This approach is not only cost-effective, but it is also easy to deploy without requiring any changes at the WiFi access point or installing special sensors in the environment. We train and test six off-the-shelf machine learning models on 15+ hours worth of WiFi MAC-layer traffic collected in a home environment. We present a proof-of-concept system prototype that employs this approach. We are able to detect six activities - (a) Walking vs Sitting, (b) Sleeping vs Awake, and (c) Using Phone vs Not Using Phone in three different real-world scenarios. Our evaluation reveals that WiFi MAC-layer traffic has special signatures to detect human activities and we are able to achieve 92.49 % detection accuracy in the best case

Comparative evaluation of single application of 2% whole turmeric gel versus 1% chlorhexidine gel in chronic periodontitis patients: A pilot study

Aim: To evaluate and compare the clinical effects of topical subgingival application of 2% whole turmeric gel and 1% chlorhexidine gel as an adjunct to scaling and root planing (SRP) in patients suffering from chronic periodontitis. Materials and Methods: Fifteen patients with localized or generalized chronic periodontitis with a pocket depth of 5-7 mm were selected. In each patient, on completion of SRP, three non-adjacent sites in three different quadrants were randomly divided into three different groups, that is, Group I: Those receiving 2% turmeric gel, Group II: Those receiving 1% chlorhexidine gel (Hexigel), and Group III: SRP alone (control site). Plaque index, gingival index, probing depth, and clinical attachment levels were determined at baseline, 30 days, and 45 days. Results: Group II as a local drug system was better than Group III. Group I showed comparable improvement in all the clinical parameters as Group II. Conclusions: The experimental local drug delivery system containing 2% whole turmeric gel helped in reduction of probing depth and gain of clinical attachment levels