Open Access Repository of Indian Theses

Mane, Harshali Dnyaneshwar

ABST'ITACT
Clobal Positioning Systenr (GPS) is one of the rnost widely used r,vireless
systems for navigation. A CiPS receiver has to lock on the satellite signals to calculate
its positiott.'l'hc proccss o1'locking and tlacking satellites recluires lreavy
corrputation" which consLlrnes both tirne ancl power. The dissertation fbcuses tlre
design and developrnent clf fast and LrninterrLrpted low porner consurning software
based CPS rece iver under the cornpressive sensing fiarnework. Ciornpressive serrsing
is recently developcd technique that exploits the sparsity,ness ol'the sigrral and
accluircs a sigrral w ith lcss nr.rrtrber of sarnple s and reconstrurct tlre signal r,r,ith
optirnization techniqLres. 'l'lris thesis addresses the developrnent of-various algorithrns
that inclLrdes (a).srrb ,surnJtlcd Fu.st Fourier 7-runsfbrnt (.s.yFFT) bu,sed GP,\ uc't1ui.;ition
algorithm und lntprrt,cd.s,;l'-l;T bu.sed (iPS uc'qui.sition (b),\ub runtplerl huscd (i[',\
trucking ulgorithnt (c) ^r,iI-FI bu,yetl cornpleta SGR tlesign (d) Sub-,yuntplad Kulmrtn
Fillcr bu,yctl GP.\ truc'king ulgorithm and (e) vulitlulion of ltrolto.serl .s1,.y1c171.
AcqLrisition is Inost inrportarrt process arrd a challenging tasl< tbr identifyirrg
visible satellites in desigrring sofnvarc CPS receiver.'['his research presents fhster
CPS accluisition via ssFF'l-.'l'his algorithrn cxploits the properties ol Fourier'
translbnn. decimator and sparsc FF-f. that redLrces the number of'conrputatiorrs.'l'he
computational complcxitl* of ;lroposecl algorithnr is 'cl log cl' tirnes lhster tharr the
conventic'rt.tztl [-'Fl- basccl acrprisition algorithrn. ulrere 'cl' is an integcr clou,n sant;llinu
f-actor. Tlre sitnulation results shows that tlre con"rpLrtation tirne fbr accluisition is
8.5571 tirres fastu'tlian tliat olconverttional [rFT'based algorithrn 1or down sarnpling
rate d 12.
l-lrc tnain goal ol'tracking is to slnchrrrrrize a localll' generatcd PRN code
(C/A codc) or replica r:rf the transrlitted PRN code with the incoming signal which is
sarne iis the accluisition.'l-his thesis desigr-ls an effective and ef'llcient trackirrg
algoritlrnr based ou .sub-sunrplcd tcc'hniqtrc it"t tirne domain and litcuses on
demodLrlation o1' (lPS signal rvith less trackins collpLttation tirne. 'l'he proposed
algorithnr cxploits the propertv o1'recentll, dcveloped Randorn Dernodulator which
ellicientll' extract the f'catures o1- received sigrral arrd lras an irnproved in cortrputatic'rn
tirre by, 31.022% against the convention tracking based algoritlrrr.
'l'he rcsealch fbcLrses on design and cievelopment ol courplete SLtb-sarnpled betsed Sofiwale
I)eflned GPS Ileceivcr (ssS(ilt) thiit conrbincs the sub-sampled based accluisitiott. sLrb-
sanrplecl based ptrll-in-treclLrencv and sub-sarnplecl basecl tracking algorithrns. [:or sallpling
lreqrrency. /, I Mtiz Qrc:t1ui.;itiori) and 5 Mtlz (pull in li'equcnt:.1t). resulting
conrputation titre is 7' ,i.4684sec. resr-rlting tirne irnprovelrent by l9.l4o%. fler the
sigrral is tracked vvith loss o1'llrst 100 sanrples but it is recovered after 100 samples.
FLrrther this rescarch clesign a CPS carrier tracking usirtg sttb .scttnpled Kulntun
/ittar bu,;ctl l'-l-1. u.;.;i.vletl I'L.L tbr processing a rveak carrier signals durirrs
scintillation. Cornpared with tlre traditional PLL.. sLrb sarrpled KF PL.L varies the
bandw,idth depending upou thc noise. RcsLrlts slrow tlral the considered s)'stcttt ctltt
operate corrtinuor-rslr, rvilhoLrt losins phase lock cven over pcriods ol-signal otttage. ln
sirnulation. visible satellites with a I'}RN 6. 10. 17.23.26.28 channels are acqttired
and are completely tracked. F-or PRN r.rurnber 28. due tolS0"plrase nreasurement
errors. loop started to slip half cycles. and eventually'it complctely lost carrier lock.
'l'he sub sarnpled Kaln'rnn based P[.L. starts trl have signilicant problelns when the 1wo
[1:p]clouds approach close enough to tlrc origin to callse thc phase lreastlretleltt
error standard deviation to be a signillcarrt fl'action of 90". Thtrs. sLrb sanrpled Kallnan
basecl t,t-1. r,r,ill track rnore robustll dLrring scirrtillation indLrced powt:r facies than a
PL.L. l6r a sigrral that carries data hits.'I'he navigation positiorr is calcLtlated b1'
processing data obtairrecl liorn proposed acquisition and lracking algttrithrrs.
'l'he 
pe rttrnrancc ol- the ssF F'l- based CPS accluisition is cotrpared arrd
evaluated using ditfbrcnt sigrral to noise ratios.'l-he Validation ol'proposed algoritlrrns
is done Lrsing rrultipath eltects and b1'adding different signal to noise ratios. The
perfbnnances ol'the ssl-'FT based GPS Acrlrrisitiorr arc cr)nrpared and evaluated usillg
dilferent Signal to noise ratios (SNR) in harsh environrnental conditions. Tlre
simulation results slrou,that thc corrsidered systetn can operate continuously witlrotrt
lail cven with very'wcak Cil'}S sigrrals. Sarre accprisition results have been obtained
with SNR valLres of -10 dt]. -ti dtl. -5 dB. -4 dB. -ldB. -ldB and ldEl tbr strbsarnplirru
lacror of-0. 2. zl. (r. tl. l0 arrd l2 respectively. The proposed algorithrr contibtttes
torvards tlre exact positionirrg rcquired irr varioLrs applicatiorrs sttch as llsherrrart. cell
phones. rtr issi le gLr idance. veh icle trackirrg. ancl disaster' llletl.)agelncllt.


English

Design and Development of software based GPS receiver using compressive sensing

Hajra, Dipasree

xxiii 
 
SYNOPSIS 
Synopsis of work done by Ms. Dipasree Hajra (SR No. 03-04-00-10-11-18-1-15842) for the 
award of Ph.D. degree in the Faculty of Science, Indian Institute of Science, Bangalore, 
India. 
Thesis Title: Understanding the mechanism of host deacetylases SIRT1 and SIRT3 in the 
modulation of Salmonella pathogenesis 
 
Chapter 1  
Introduction 
Salmonella continues to be a threat to the human population by taking a toll on the lives of 
about 20,000 individuals globally per year. Salmonella enterica serovar Typhimurium is a 
facultative intracellular Gram-negative enteric pathogen, causing a wide array of infections 
ranging from self-limiting gastroenteritis to diarrhoea in humans. Salmonella enterica serovar 
Typhi cause systemic infection in humans with typhoidal symptoms. Recent reports reported 
21 million typhoid cases and 93 million non-typhoidal cases year-round. The virulence of 
Salmonella is majorly regulated by two pathogenicity islands, namely, SPI-1 and SPI-2. It uses 
SPI-1 encoded T3SS and the effector proteins to invade host cells.  Inside the macrophages, 
they reside within the Salmonella-containing vacuoles (SCV) by virtue of its SPI-2 effectors. 
Macrophages, dendritic cells, and neutrophils are responsible for successful dissemination 
throughout the body through the reticulo-endothelial system (RES).  
Sirtuins are NAD+-dependent deacetylases that are present in all forms of life. Saccharomyces 
cerevisiae serve as the founder for the discovery of Sir2. Sirtuins comprise a conserved core 
catalytic domain that removes acetyl moiety from the lysine residues of proteins in the presence 
of NAD+ as a cofactor giving rise to 2’O-acetyl-ADP-ribose and free nicotinamide as products. 
xxiv 
 
Host Sirtuins are one of the important modulators of host immuno-metabolic regulation. 
However, the role of Sirtuins in the modulation of the immune metabolism pertaining to 
Salmonellosis is largely unknown. Here, we investigated the role of two important Sirtuins, 
SIRT1 and SIRT3 in the modulation of Salmonella pathogenesis. We have shown that 
Salmonella-induced modulation of SIRT1 and SIRT3 is crucial for governing immune-
metabolic switch in the host and this switch influences the metabolic profile of intracellular 
Salmonella (Chapter 2).  Moreover, SIRT1 and SIRT3 regulate the mitochondrial 
bioenergetics and dynamics in the S. Typhimurium infection scenario. SIRT1 and SIRT3 
mediated alteration of mitochondrial bioenergetics help in the maintenance of intracellular pH 
of both the host and the bacteria, thereby influencing the bacterial intracellular niche (Chapter 
3). In in vivo model of mouse infection, SIRT1 and SIRT3 have been shown to regulate 
Salmonella dissemination in blood and other secondary organs. However, O. splanchnicus gut 
colonization reversed the Salmonella-associated dissemination in mice. (Chapter 4). 
Chapter 2 
Salmonella-induced SIRT1 and SIRT3 are crucial for maintaining the metabolic switch 
in bacteria and host for successful pathogenesis                     
We have elucidated the role of SIRT1 and SIRT3 in mediating metabolic switch in Salmonella 
and its implication in establishing pathogenesis. Our study indicated the ability of the live 
Salmonella Typhimurium to differentially regulate the levels of SIRT1 and SIRT3 for 
maintaining the high glycolytic metabolism and low fatty acid metabolism in Salmonella. Upon 
SIRT1 or SIRT3 knockdown or inhibition, the metabolism in intracellular Salmonella switched 
to high fatty acid oxidation and low glycolysis. This switch led to decreased proliferation of 
Salmonella in the macrophages. Further, Salmonella-induced higher levels of SIRT1 and 
SIRT3 led to a skewed polarization state of the macrophages from a pro-inflammatory M1 state 
xxv 
 
toward an immunosuppressive M2 making it more conducive for the intracellular life of 
Salmonella. Alongside, immunological functions by modulating p65 NF-κB acetylation, 
SIRT1, and SIRT3 also skew Salmonella-induced host metabolic switch by regulating the 
acetylation status of HIF-1α and PDHA1. Interestingly, though knock-down of SIRT1 and 
SIRT3 attenuated Salmonella proliferation in macrophages, in in vivo mice-model of infection, 
inhibition of SIRT1 and SIRT3 led to more dissemination and higher organ burden which can 
be attributed to enhanced ROS and IL-6 production. Our study hence reports for the first time 
that Salmonella modulates SIRT1 and SIRT3 levels to maintain its own metabolism for 
successful pathogenesis. 
Chapter 3 
SIRT1 and SIRT3 mediated modulation of mitochondrial bioenergetics and dynamics 
during Salmonella infection in macrophages skews both host and bacterial intracytosolic 
pH 
Mitochondria are considered to play a central role in the regulation of host cellular processes 
and host responses pertaining to bacterial infections. Numerous microbial pathogens modulate 
mitochondrial functions and dynamics to evade host immune responses. On the other hand, the 
elicited host immune responses are dependent on the overall mitochondrial bioenergetics and 
their function. Thus, mitochondrial health is a crucial determinant for the outcome of several 
bacterial infections. We have explored the role of host deacetylases SIRT1 and SIRT3 in the 
modulation of mitochondrial bioenergetics and dynamics pertaining to Salmonella infection. 
Here, we show that inhibition of SIRT1 or SIRT3 function either by shRNA-mediated 
knockdown or by the application of specific catalytic inhibitors leads to increased 
mitochondrial dysfunction in the Salmonella-infected macrophages. We have shown that 
inhibition of SIRT3 function leads to increased production of mitochondrial superoxide 
xxvi 
 
generation in the infected macrophages. The increased mitochondrial ROS generation in the 
infected macrophages coincides with mitochondrial membrane hyperpolarization, increased 
proton leakage and respiration rate, and a decline in ATP production and ETC function. The 
mitostress profile suggested an overall increase in respiration parameters such as basal 
respiration, non-mitochondrial respiration, proton leakage and ATP-linked respiration along 
with an increase in Extracellular Acidification Rate (ECAR) upon both SIRT1 and SIRT3 
inhibitor treatment. The mitochondrial bioenergetic alteration triggers increased acidification 
of the macrophage cytosolic pH which in turn skewed the intra-bacterial pH of the intracellular 
bacteria within the SIRT1 and SIRT3 knockdown and inhibitor-treated macrophages. Here, we 
show that loss or inhibition of SIRT1 or SIRT3 trigger increased acidification of the 
macrophage cytosol which consequently lead to a loss in intra-bacterial acidification together 
resulting in decreased SPI-2 gene expression. Alongside the decline in mitochondrial 
bioenergetics, the S. Typhimurium infected macrophages depict alteration in mitochondrial 
dynamics with increased mitochondrial fission and mitophagy alongside decreased 
mitochondrial fusion dynamics. Together, our results suggest the role of SIRT1 and SIRT3 in 
preserving the mitochondrial bioenergetics and dynamics in S. Typhimurium infection scenario 
and thereby influencing the bacterial intracellular niche. 
Chapter 4 
Odoribacter splanchnicus mitigates Salmonella-induced gut inflammation and its 
associated pathogenesis in mice  
The existence of the gut vascular barrier (GVB) acts as a protective barrier against the entry of 
microorganisms into systemic blood circulation. Enteric pathogens such as Salmonella enterica 
can cross the mucus and intestinal epithelial barrier, ultimately leading to GVB damage and 
systemic dissemination. The gut microbiota plays another major role in the maintenance of the 
xxvii 
 
intestinal epithelial barrier by the production of several metabolites such as Short-chain fatty 
acids (SCFAs), indoles, and polyphenol metabolites that contribute to epithelial barrier 
integrity and turnover by regulating the expression of Tight-junction (TJ) genes. Our previous 
study reported an incidence of increased Salmonella dissemination in blood, liver, and spleen 
upon SIRT1 and SIRT3 inhibition owing to the increased inflammatory response. Here, we 
aimed to understand this exact mechanism of Salmonella dissemination and whether 
colonization with a gut commensal like Odoribacter splanchnicus could ameliorate the 
increased Salmonella-induced inflammation and in turn its pathogenic dissemination. 
Odoribacter splanchnicus, belonging to the order Bacteroidales, is a common, member of the 
human intestinal microbiota and its decreased abundance has been linked to different 
microbiota-associated diseases, such as non-alcoholic fatty liver disease, cystic fibrosis and 
inflammatory bowel disease (IBD). Our study depicts the capability of O. splanchnicus in 
reversing the Salmonella-associated pathogenesis in mice. O.splanchnicus  gut colonization 
mitigates the Salmonella-associated epithelial tight junction disruption by restoring epithelial 
tight junction function and by preventing gut vascular barrier disruption, angiogenesis, and 
inflammatory response.  
Conclusion and Significance 
Salmonella-induced SIRT1 and SIRT3 together play a pivotal role in the maintenance of the 
intracellular replication niche of Salmonella Typhimurium by regulating both host and bacterial 
metabolism and via the modulation of mitochondrial bioenergetics and dynamics within the 
infected macrophages. In in vivo mice model of infection, inhibition of SIRT1 and SIRT3 led 
to more dissemination and higher organ burden which can be attributed to enhanced ROS and 
IL-6 production. O.splanchnicus, a gut commensal,  gut colonization reverses the Salmonella-
associated pathogenesis in mice by restoring epithelial tight junction function, inhibiting the 
inflammatory response, and preventing gut vascular barrier disruption. 


Understanding the mechanism of host deacetylase SIRT1 and SIRT3 in the modulation of Salmonella Pathogenesis

Tatta, Eswara Rao

 
xi 
 
Summary 
 
Nosocomial infections are severe in nature and a challenge to treatment due to the 
emergence and extent of multidrug-resistant nosocomial pathogens, such as 
Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Klebsiella 
pneumonia, Pseudomonas aeruginosa, and Enterococci spp. The vancomycin-resistant 
Enterococcus faecalis (E. faecalis) is widely distributed globally in hospital 
environments as an opportunistic pathogen which can cause a wide range of infections 
like bacterial meningitis, urinary tract infections, endocarditis, surgical site, and 
bloodstream infections. The propensity of Enterococcus faecalis to form biofilms by 
regulating gene expression through quorum-sensing mechanisms is a fundamental 
element in its pathogenicity. Understanding the role of biofilm formation and quorum 
sensing in antibiotic resistance is crucial for developing effective strategies to combat 
infections caused by E. faecalis. In this thesis, we have performed in silico, in vitro, 
and transcriptome profiling through combinatorial treatment approaches for disrupting 
biofilm, inhibiting quorum sensing signaling, and developing alternative treatments for 
biofilm-associated infections for potential drug discovery against E. faecalis infections. 
The novel phenol (Rubrivivaxin) and indole (Rhodethrin) terpenoid compounds target 
the preliminary adherence phase of the biofilm development by hindering the cell 
surface hydrophobicity and extracellular polymeric substance (EPS) production, which 
is highly resistant to harsh environmental conditions and antibiotic therapy. These 
terpenoid derivatives (Rhodethrin (Rdn) and Rubrivivaxin (Rbn)) were found to have 
the antibacterial activity to inhibit bacterial growth as well as the motility of bacterial 
colony migration and expansion, which are used to control the infections associated 
with biofilm production. The characteristic feature of the EPSs is to form a protective 
defense and provide nutrients to the encased biofilm developed microorganisms. These 
molecules inhibit biofilm formation and disrupt the ultra-structure of biomass. 
Chloramphenicol has become an attractive antibiotic against E. faecalis due to its 
antimicrobial and antibiofilm efficacy. However, combining natural indole terpenoid 
compounds with antibiotics can often lead to synergistic effects, where the combined 
activity is greater than the sum of their individual effects.  
Our results show the in silico and in vitro antimicrobial and antibiofilm activities of 
Rhodethrin and chloramphenicol against E. faecalis in isolation and combination. 
Further, we confirmed the efficacy of their mechanism of action on biofilm. After the 
synergistic combination treatment, they significantly reduced the viable cell count, dry 
 
xii 
 
weight, protein, and eDNA concentrations in matured biofilm. The respective biofilm 
proteins were found to be 39.7±5.1% (Rhodethrin), 32.6±4.7% (Chloramphenicol), and 
69.0±5.3% (Rdn-Chpl) (p ˂ 0.05). Reduction of EPS was found to be 34.6±4.6% 
(Rhodethrin), 31.0±5.2% (Chloramphenicol), and 76.0± 4.5% (Rdn-Chpl) (p ˂ 0.05). 
Reduction of EPS was found to be 34.6±4.6% (Rhodethrin), 31.0±5.2% 
(Chloramphenicol), and 76.0± 4.5% (Rdn-Chpl) (p ˂ 0.05) significantly inhibited the 
biosynthesis of EPS. Thus, the combination of Rdn and Chpl shows a high activity as 
compared to individual treatment of E. faecalis. The inhibitory effect on EPS 
biosynthesis indicates that the combination treatment disrupts the production of key 
components required for biofilm formation. The synergistic inhibitory effect of 
Rhodethrin and chloramphenicol on the construction of biofilm and EPS biosynthesis 
in E. faecalis highlights the potential of using combination therapies to combat biofilm-
associated infections. These results show an enhanced activity of the combination 
compared to the individual treatment. The combination of Rdn and Chpl could be a 
promising therapeutic strategy to improve treatment efficacy against E. faecalis 
biofilms. 
We have performed microscopic analysis to visualize and confirm the effects before 
and after the treatments. Our observations confirmed that combination treatment led to 
greater dispersal of bacterial cells, resulting in decreased cell clustering and aggregation 
within the biofilm matrix. Understanding the mode of action of Rdn in disrupting 
biofilm formation and inhibition of EPS biosynthesis would provide valuable insights 
into developing more effective therapies. This dispersal effect indicates that the 
combination treatment disrupts the bacteria to adhere and form cohesive structures 
within the biofilm. The total EPS dry weights were estimated to be 97.50 µg/g 
(Control), 58.37 µg/g (Rhodethrin), 62.04 µg/g (Chloramphenicol), and 23.58 µg/g 
(Combination). The EPS protein concentrations were 80.88 µg/g (Control), 19.41 µg/g 
(Chloramphenicol), 15.53 µg/g (Rhodethrin), and 8.84 µg/g (Combination) (p ˂ 0.05). 
Thermogravimetric and X-ray analysis revealed the pyrolysis of polysaccharide 
crystals and crystalline domains to be 40-60% and that of amorphous domains to be 60-
75% of EPSs distractions. On the other hand, FTIR analysis shows the presence of 
functional groups (hydroxyl, aliphatic CH2, asymmetrical C=H stretching, aliphatic 
methyl, and primary amine groups), and LCMS analysis shows the disintegration of 
biopolymeric EPS components. The SEM analysis of EPSs witnessed a condensed 
matrix within polymeric carbohydrate and filamentous structures. These results show 
 
xiii 
 
the degradation of high molecular biopolymers into low or intermediate by-products of 
EPS. This treatment disrupted EPS composition and inhibited biofilm formation in E. 
faecalis cultures. 
Further, to evaluate the effects of Rhodethrin in combination with chloramphenicol on 
E. faecalis cultures, identified the differentially expressed genes (DEGs). In the 
transcriptome analysis, out of 379 differentially expressed genes, 264 genes were 
significantly down-regulated, indicating that 69.69% of the E. faecalis genome was 
altered. These differentially expressed genes included 448 genes in Control Vs. Rdn, 
1591 in Control Vs. Chpl, and 379 in Control Vs. Combined (Rhodethrin and 
chloramphenicol). qRT-PCR was used to analyse the transcriptional sequence data 
further. The results demonstrated that the treatment significantly suppressed the 
expression profiles of four genes involved in antibiotic resistance (liaX, typA, EfrA, and 
lepA), three genes expressed in quorum sensing (camE, fsrC, and sylA), and five genes 
were essential for biofilm formation (Ace, AtpB, lepA, bopD, and typA). This 
transcriptome analysis suggested that Rhodethrin and chloramphenicol might have 
different action mechanisms for inhibiting biofilm formation and quorum sensing in E. 
faecalis. The chloramphenicol disturbs the biofilm formation and inhibits the synthesis 
of enterococcal surface protein (ESP), faecal streptococci regulator-C (fsrC), adhesion 
of collagen of E. faecalis (Ace), biofilm on plastic (Bop) proteins and polysaccharides 
associated with biofilm formation, promotion of cell aggregation and adherence to 
surfaces. Whereas, Rhodethrin induces the inhibition of outer membrane protein (liaX), 
mediating cell membrane remodeling, camE encoding sex pheromone associated with 
quorum sensing, and large extracellular protease (lepA) associated with virulence 
expression. 
The above findings stated that the combination of Rhodethrin and chloramphenicol had 
shown great promise in inhibiting biofilm encasement, quorum sensing, and antibiotic 
resistance of E. faecalis. Combining these two compounds is more effective at 
inhibiting biofilm formation than using either compound. These findings suggest the 
potential use of this combination as a therapeutic approach to combat E. faecalis 
infections by targeting multiple aspects of the bacterial phenotype. However, further 
research is needed to uncover the underlying mechanisms and optimize the treatment 
strategy for clinical application. 


Synergistic Studies of Rhodethrin and Chloramphenicol on the Biofilm Architecture, Antibiotic Resistance and Quorum Sensing against Enterococcus faecalis

M, Karuppusamy

  Abstract 
 
 423  
 
ABSTRACT  
-------------------------------------------------------------------------------------------------------------------------- 
Name of the Student: M. Karuppusamy Registration No.: 10CC16A11003 
Faculty of Study: Chemical Sciences Year of Submission: 2023 
AcSIR Academic Centre/CSIR Lab:  
CSIR - Central Leather Research Institute 
Name of the Supervisor: Dr. S. Easwaramoorthi 
Name of the Co-Supervisor: Dr. V. Subramanian 
Title of the Thesis: Rational Design and Development of Organic Electronic Materials using 
Density Functional Theory Methods 
---------------------------------------------------------------------------------------------------------------- 
One crucial aspect of designing organic energy materials is understanding the role 
of molecular structures and their impact on their properties. In this thesis, an attempt has 
been made to develop the structure-property relationship by considering examples of 
different organic electronic materials with application potential in harvesting solar 
energy and organic light-emitting diodes through computational chemistry methods. 
Fundamental challenges in the design and development of organic electronic materials 
and the scope of the investigation are presented in Chapter 1. 
  
The possible development of a structure-aromaticity-conjugation spectroscopy 
relationship (SACSR) is presented in Chapter-2. 
 
Chapter 3 presents the design of a series of organic dye molecules using ullazine 
and perylene employing D-π-A topology, with ullazine analogs as donors and perylene 
dicarboxylic anhydride as an acceptor along with acetylene linker as π-bridge for DSSC 
applications. The findings will be beneficial in designing efficient and cost-effective 
organic dyes for solar energy conversion.  
 
A comprehensive investigation into the optoelectronic properties of electron 
donor-based molecules, having Isoindigo (IIG) moiety for their potential application in 
efficient OSCs is described in Chapter 4. Findings highlight the potential of central group 
modifications and spacer effects in enhancing the efficiency of organic solar cells for the 
D2-A-π-D1-π-A-D2 framework. These findings contribute to the ongoing development of 
sustainable and efficient solar energy technologies based on organic materials. 
 
Chapter 5 focuses on the design and characterization of a series of triazine-based 
systems for OLED applications utilizing the TADF mechanism. The molecules investigated 
include diphenylamine (DPA), triphenylamine (TPA), carbazole (Cbz), indolocarbazole 
(ICbz), dimethyl acridine (DMAC), phenoxazine (PXZ), phenothiazine (PTZ), diphenyl 
acridine (DPAC), diphenyl azasiline (DPAS), spiro acridine fluorene (SAF), and spiro silole 
azasiline (SSiAS). The findings point out the potential of these molecules as blue emitters 
and underscore the importance of further investigations to optimize their performance 
and efficiency. The insights gained from this research contribute to the advancement of 
organic electronics, specifically in the development of high-performance OLED devices. 
 
Chapter 6 summarizes the primary results and conclusions that were derived 
from the present investigation. 
 


Rational Design and Development of Organic Electronic Materials Using Density Functional Theory Methods

Rose, Biju Ben

iii 
 
ABSTRACT 
 A laboratory-scale scramjet thruster was the subject of an experimental 
investigation to determine the effects of a strut extending across the width of a 
single expansion ramp. The strut was positioned on the expansion ramp's 
surface twice: once in the middle of the ramp's span and once at the ramp's 
trailing end. The trials were carried out at each of the six strut heights using six 
different thruster pressure ratios (TPR), or ratios of inlet total pressure to 
ambient pressure, ranging from 5 to 10. The thruster's internal wall pressure 
distributions and the Schlieren images of the flow were experimentally 
obtained. It was investigated if it would be possible to control a hypersonic 
vehicle that typically uses aerodynamic control by adding a strut as a secondary 
device in the thruster. The combustor's inlet Mach number was 1.8. An isolator, 
a diverging area combustion chamber, and a single expansion ramp made up 
the thruster model. A supersonic nozzle with a rectangular exit that matched the 
proportions of the rectangular isolator provided the flow for the thruster's inlet. 
The bottom wall of the rectangular diverging combustor was flat, and the upper 
wall inclined the bottom wall by 2.44 degrees.  
The wall pressure was measured at various points between the ramp 
trailing edge and the combustor inlet. The Schlieren pictures were utilized to 
study the shock pattern, and it was found that an increase in strut height resulted 
in a downward deflection of the exhaust. Two-dimensional side force and 
pitching moment coefficients were computed from the wall pressure 
distribution, and the influence of strut height variation on the aforementioned 
coefficients was shown. The presence of the strut produced observable changes 
in side force and pitching moment, according to experiment results. The 
increase in strut height produced changes in the direction of the exhaust stream, 
which may be helpful when steering vehicles powered by scramjets. 
iv 
 
At all expansion levels of the ramp nozzle, or for all the TPRs used in 
the current investigation, higher strut heights led to an increase in the side force 
coefficient (5 to 10). Similar to how the side force coefficient varied with strut 
height, the pitching moment coefficient did as well. The nature of these 
variations remained the same when the strut was moved from the expansion 
ramp's tail end to the ramp's middle location. Although the majority of these 
variations were nonlinear in nature, the degree of nonlinearity varied depending 
on the TPR value. At TPRs 5, 9, and 10, there was a greater nonlinearity in the 
variation of the side force coefficient. When compared to the ramp tail end 
location, the moment coefficients for the strut's mid-ramp position were larger 
at lower TPR. Ramp surface flow was noticeably deflected downhill by tall 
struts. Schlieren’s pictures revealed a downward deflection in the exhaust flow 
over the expansion ramp, with the position and height of the struts having an 
impact on the deflection's size. The aforementioned studies were conducted 
again for ramp inclination angle ranges of 0 to 8 degrees.  
 In terms of side force and moment coefficients over the scramjet 
thruster, the results were compared for various TPRs, strut position, strut height, 
and ramp inclinations. Larger jet deflections were seen at practically all TPRs 
when comparing the near trailing edge position of the strut on the expansion 
ramp to the mid-length position. The expansion ramp had larger pressure peaks 
as a result of the taller struts, which altered the side force coefficient. Large 
strut heights also resulted in bigger pressure zones on the expansion ramp when 
the strut was positioned in the middle of the ramp. An increase in ramp 
inclination angle resulted in a decrease in flow deflection angle when struts 
were present (downward). This was noticed at every TPR.  


EXPERIMENTAL STUDIES ON INTERACTION OF A SUPERSONIC FLOW WITH A STRUT PLACED ON AN EXPANSION RAMP

M, SATHISH KUMAR

Abstract/Synopsis:  The main objective of this thesis is to develop polyaniline-based 
nanocomposite active electrode materials with high specific capacitance as well as cyclic 
stability, for supercapacitor applications. Intrinsic polymers play a key role in 
supercapacitor application because of their high corrosion resistance, flexibility, and good 
adhesion. Polyaniline is considered among all conducting polymers to be a promising 
supercapacitor material due to its superior properties such as multiple redox behavior, 
simple processability, high conductivity, and easy morphological alignment. Despite being 
one of the best supercapacitor materials, polyaniline has some disadvantages including poor 
cyclic stability (~1000 cycles) and low energy density. Several strategies have been adopted 
in the literature to overcome these issues. One of the strategies to develop nanocomposites 
of polyaniline with metal oxides and carbon-based materials. These nanocomposites show 
unique morphologies along with improvement in the specific capacitance and cycle life.  
In this study, we have synthesized and evaluated the performance of several polyaniline-
based nanocomposites. The first one we prepared was carbon-polyaniline nanocomposites 
namely, carbon nanotube-polyaniline, graphene oxide-polyaniline, and carbon nanotubes-
graphene oxide-polyaniline. These nanocomposites benefit from the high specific surface 
area, high flexibility, and tensile strength of the carbon nanoforms, which improve the 
specific capacitance, allow high volumetric changes in the electrode material without 
degradation and as a result, provide better cyclic stability. The carbon nanoforms in 
polyaniline provide greater connectivity between the material domains. This enhanced 
connectivity and the resulting improved transport of charges could also be a key factor 
responsible for improving the cyclic stability of the polyaniline nanocomposite as a 
supercapacitor material. In any case, carbon-polyaniline nanocomposite supercapacitors 
show comparatively low specific capacitance (234, 265, 373F/g) values.  
To solve this problem, a porous nickel cobaltite was incorporated into the polyaniline. 
Nickel cobaltite has high electrochemical activity and conductivity on account of the co-
existence of two distinct cations in a single crystal. Porosity was introduced in nickel 
cobaltite by a glycine-assisted hydrothermal synthesis method. With the help of strong 
electrode/electrolyte interface, higher surface area (176 m2/g) because of the porous nature 
of glycine-assisted nickel cobaltite a moderate specific capacitance (688 F/g) with good 
cyclic stability (88% over 1000 cycles) was obtained. However, the specific capacitance 
has been moderately achieved, the cyclic stability will be lower if the cycles rise above 
1000. Also, the electrochemical performance will be lost while making a two-electrode 
device due to poor adhesion. 
 To solve those problems polyaniline composite was made using carbon quantum dots 
which were hydrothermally synthesized using urea and glycine as a source. Polyaniline 
supplies pseudo-capacity for the composite and carbon quantum dots supplies a high 
surface area, enhanced electron transport, and potentially improved durability. When used 
as a precursor to polyaniline, CQDs are uniformly distributed, well-spaced, and isolated 
from each other without any agglomeration contributing to a long nanotube morphology. 
This type of long rod-like morphology leads to high interfacial interactions between 
polymers and CQDs, which can accommodate more ion transport and reaction sites, as well 
as the high specific capacitance of 871 F/g and 84.5 % retention in specific capacitance 
over 3000 cycles for a three-electrode system. The two-electrode device achieved a 161 
mF/cm2 areal-specific capacitance and cyclic stability of 85 % over 5000 cycles with this 
material.  
The final material produced was a less time-consuming new organic nanostructure at a low-
temperature simple heating method, which was later decorated with polyaniline. Because of 
the generation of more active charge storage sites leads to high interfacial interaction 
between organic nanostructures and polyaniline, this composite exhibits improved 
electrochemical performance in both liquid-based and solid-state systems. Excellent cyclic 
stability (85 % over 3000 cycles) and enhanced specific capacitance (779 F/g) have been 
achieved by a three-electrode system. The two-electrode device achieved an areal-specific 
capacitance of 650 mF/cm2 with outstanding cyclic stability of 96 % up to 5000 cycles.  
Although polyaniline has some superior properties, the low rate and cyclic stability are key 
issues associated with polyaniline electrodes. These issues were overcome by the efficient 
combination of polyaniline with the above-mentioned materials as composite electrodes.   


POLYANILINE BASED NANOCOMPOSITES FOR SUPERCAPACITOR APPLICATIONS

Singla, Sushil

BIRKHOFF-JAMES ORTHOGONALITY AND DISTANCE FORMULAS IN C∗-ALGEBRAS AND
FOR TUPLES OF OPERATORS

This thesis is devoted to the study of Birkhoff-James orthogonality in C∗-algebras
and its applications in finding some distance formulas. We start with a thorough survey on the literature of Birkhoff-James orthogonality in the first chapter. Motivated
from the characterizations of Birkhoff-James orthogonality in the space of continuous
functions on a compact Haudorff space and the space of matrices, we prove a characterization of Birkhoff-James orthogonality in general C∗-algebras and Hilbert C∗-modules. 

We provide three different proofs of our characterization with different themes in the
second chapter. It is shown that most of the results in the first chapter follow as applications of our characterization. Some new theorems are also proved. In the third chapter, applications of our characterization in the geometry of Banach spaces are mentioned and connection of orthogonality characterizations and distance problems is discussed. In the fourth chapter, we show the applications of our results for finding characterizations of orthogonality for tuples of operators. We also provide a distance formula in terms of variance of tuples of operators. Various possible directions for future work are mentioned throughout the thesis and are collected at the end for easy reference.


Birkhoff-James Orthogonality and Distance Formulas in C∗-Algebras and for Tuples of Operators

Tiwari, Aparna

 
 
Role of malaria exposure on renin-angiotensin aldosterone system polymorphisms and 
hypertension  
 
 
Quite contrary to malaria, the burden of hypertension is rapidly increasing in the tropical world 
and their inverse disease burden trend observed in India suggests a potential inter-
relationship. This inverse trend is scientifically explainable with existing evidence. Many 
investigators have suggested that antecedent malaria exposure predisposes individuals to 
hypertension risk. One such evolutionary adaptation hypothesized and studied, although 
scarcely, is the occurrence of severe malaria protective polymorphisms in the human Renin 
Angiotensin Aldosterone System (RAAS) that involves the two functionally pivotal enzymes, 
ACE and ACE2, the actions of which are crucial for maintaining the blood pressure 
homeostasis. We tested this hypothesis by exploring the association between malaria and 
hypertension risk via RAAS mutations using Mendelian randomization on the basis of the 
sickle-cell trait (HbAS).  
 
A literature review outlining the basis of the malaria-hypertension hypothesis and Mendelian 
randomization was conducted. Two independent association studies were performed, using 
HbAS as a marker for presence of severe malaria (SM) pressure and using SM cases using 
a case-control design. In vitro Plasmodium falciparum assay was also conducted to explore 
the anti-Plasmodium activity of ang II.  
 
The susceptibility (HbAA) to SM was found to be 94% in the studied states of India. With the 
use of HbAS as a surrogate marker, DD genotype of ACE was found to be statistically 
significantly and positively associated (p value <0.05) with the individuals with SM pressure 
and survival advantage (SMPSA). In case-control study, RAAS polymorphisms (ID genotype 
of ACE) was found to be in statistically significant negative association with SM (OR 0.45; 95% 
CI 0.24-0.86)). Ang II was found to have an inhibitory role at 10-6 M (in Pf invasion) and at 10-
9 M and 10-7 M as IC50 on ring and schizont growth of Pf, respectively.  
 
Malaria exposure has a role on RAAS polymorphism specifically on DD and ID genotype of 
ACE. Ang II has inhibitory effects on Plasmodium falciparum with unknown mechanism of 
action. Hence, it can be concluded that such polymorphisms in RAAS may protect from SM 
and therefore get positively selected under SM pressure but also aggravate the risk of 
hypertension. Future work should focus on confirming the findings using alternative study 
designs such as a population-based study by avoiding suggested limitations in which 
components of RAAS polymorphisms, levels and activities of ACE and ACE2 including blood 
pressure can be examined and selection tests must be applied to confirm whether these 
polymorphisms are under malaria pressure.  


Role of malaria exposure on renin-angiotensin aldosterone system polymorphisms and hypertension

Saryal, Sushant

Universal bounds on fluctuations in thermal machines and thermal transport junctions 
 
The second law of thermodynamics forbids the possibility of a perpetual machine of a second 
kind. It provides a universal upper bound on the efficiency of any thermal machine operating 
between two heat baths, famously known as Carnot Efficiency. But traditional thermodynamics 
was only concerned with average quantities because typically, fluctuations can be ignored for 
macro systems, for example, steam engines, automobile engines, etc. With the rapid 
technological development over the last several decades, we can now investigate systems of 
sizes that can range from hundreds of nanometers to a few nanometers, such as quantum dots, 
molecular motors, single atoms, etc, at temperatures that range from micro to nano Kelvin. As a 
consequence of these advancements, in the past two decades, various small-scale thermal 
machines have been realized using state-of-the-art experimental techniques like ultra cold atoms, 
single colloidal particles, single-molecule optomechanical systems, and Paul ion-trap technique, 
etc. Since these devices operate away from equilibrium, understanding non-equilibrium 
thermodynamic properties of such small-scale systems is an active area of research where one 
can no longer ignore the role of fluctuations of thermal and/or quantum origins and therefore a 
proper probabilistic description is required. Thus, a natural question arises that whether any 
universal bound exists on the fluctuations as well? In this thesis, we attempt to shed light on 
understanding properties of fluctuations in non-equilibrium systems and its impact on the 
performance of thermal machines by providing universal bounds on the fluctuations of the 
underlying currents. We will first show that, for a time-reversal symmetric continuous thermal 
machines, the relative fluctuation of the output current is always greater than the relative 
fluctuations of the input current in linear response. As a consequence, the ratio between the 
fluctuations of the output and input currents are bounded both from above and below, where the 
lower (upper) bound is given by the square of the averaged efficiency (square of the Carnot 
efficiency) of the thermal machine. Then we will generalize our findings to the machines with 
broken time-reversal symmetry. Later we elaborate an extension of our work to the finite-time 
quantum cycles, in particular for quantum Otto machines. All of these above studies and obtained 
universal results uncover a novel relationship among the recently discovered trade-off relations 
for individual currents, famously known as Thermodynamic Uncertainty Relation (TUR). TUR 
provides bound on relative fluctuations of individual current in terms of associated entropy 
production. Our work in the context of thermal machines reveals that TUR for individual currents 
are not independent of each other but follow a strict hierarchy in the operational regime. 


Universal bounds on fluctuations in thermal machines and

thermal transport junctions

M, Avinash

INVESTIGATIONS ON THE STRUCTURAL, OPTICAL AND 
MAGNETIC PROPERTIES OF STANNATE BASED PEROVSKITE 
SYSTEMS 
Stannates have received both industrial and application interest among the research fraternity 
for the past few decades. In particular, perovskite structured stannates  with formula (MSnO3) 
where M=Ba, Ca, Sr have been explored enormously due to their interesting structural and 
physical properties such as optical and magnetic characteristics. Tuning their behaviour can 
pave way for many arenas in material science like spintronics, magnetic memory devices, 
luminescence, gas sensors and dielectrics etc. It is a well-known phenomenon that structural 
properties such as crystal structure, crystallite size and strain are greatly influenced by the 
method of synthesis and have a considerable impact on the application. Added to this, the 
introduction of dopant ions in the host system tend to unfurl stimulating optical and magnetic 
properties due to its adaptable crystal structure. The present thesis focuses on two perovskie 
systems namely, BaSnO3 (BSO) and CaSnO3 (CSO). BSO belongs to cubic perovskite structure and 
CSO belongs to orthorhombic perovskite structure. The advantage of stannates is that they can 
be prepared using various synthesis methods. Although many works of literatures are available 
related to dye-sensitized solar cell (DSSC), gas sensors, thermally stable capacitors and 
photocatalytic activity etc, a detailed observation on the changes in magnetic and optical 
behaviour upon the dopant incorporation is least reported. Hence the present work studies the 
structural, optical and magnetic properties of transition (Cr3+), post-transition (In3+) and rare 
earth (Pr3+) doped barium and calcium stannate perovskite system. To explore the doping 
effects, BaSn1-xCrxO3, BaSn1-xInxO3, BaSn1-xPrxO3 and CaSn1-xPrxO3 are synthesized by chemical co-
precipitation method and characterized by various analytical measurements to extensively 
analyze the physio-chemical characteristics. The thesis introduces with a brief description of the 
current trends in the electronic industries, and the importance of dilute magnetic 
semiconductors (DMS). Further, various exchange mechanisms of magnetism and 
ferromagnetism in oxide materials are dealt with. Detailed literature on the perovskite stannate 
systems along with the aim and scope of the thesis is also given. The second chapter elaborates 
the synthesis methods adopted in the thesis, its importance and further explains the analytical 
characterization measurements that are performed to investigate the physico-chemical 
properties of the synthesized perovskite materials. The effect of Cr3+ (chromium) ions on the 
structural, optical and magnetic properties of BaSnO3 compounds are discussed in the third 
chapter. XRD studies delineate the cubic structure and Raman measurements support the role 
of oxygen vacancies. Morphological changes are observed upon doping. UV-Vis DRS 
measurements indicate a change in the bandgap. Photoluminescence studies validate the 
existence of defects. Mössbauer measurements establish tetravalent state of Sn. EPR 
measurements suggest the existence of oxygen vacancies. VSM measurements reveal a change 
in diamagnetic to ferromagnetic behaviour upon Cr doping. The observed transition in magnetic 
characteristics may be due to the F-centre exchange interaction. The effect of In3+ (indium) ions 
on the structural, optical and magnetic properties of BaSnO3 compounds are discussed in the 
fourth chapter. XRD results indicate the cubic crystal structure. Defects such as oxygen 
vacancies are identified from Raman modes. Changes in morphological shape are witnessed 
from HR-SEM measurements. Variations in optical band gap and defect states are identified 
from UV-Vis DRS and photoluminescence studies. Mössbauer results indicate the tetra valent 
state of Sn. EPR measurements validate the presence of oxygen vacancies. A characteristic 
change from diamagnetic to ferromagnetic behaviour is understood from VSM studies. The 
effect of Pr3+ (praseodymium) doping on the structural, optical and magnetic properties of 
barium and calcium stannate based perovskite systems is discussed in the fifth chapter. The first 
part of the chapter elucidates the role of Pr ions on the BaSnO3 lattice. The second part of the 
chapter investigates the role of Pr ions on the CaSnO3 lattice. Interesting structural, optical and 
magnetic properties of Pr doped BaSnO3 and CaSnO3 compounds are discussed. Finally, the 
thesis is presented with summary and suggestions for future work. 


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