Open Access Repository of Indian Theses

Swagatika, Swati

vii 
 
ABSTRACT 
Cantharidin (CAN) is a terpenoid compound of insect origin with the Spanish fly, Cantharis 
vesicatoria, probably being the best-known source. CAN is naturally produced by the male blister 
beetles as an anti-predatory mechanism and is presented to their female partners as a copulatory gift 
to defend their eggs from predators. It was initially discovered in 1910 by a French chemist Robiquet. 
Since the time of its discovery, this molecule has been widely studied to understand its mechanism(s) 
of action and its role as an anticancer molecule. So far CAN has been shown to induce DNA damage, 
cell death through G2/M phase cell cycle arrest, apoptosis and MAPK signaling pathway 
Additionally, it is known to suppress protein phosphatase 2A (PP2A), a positive regulator of cell 
growth and division, and cancer metastasis. In yeast, CAN has been reported to be rendered inactive 
post methylation by a protein cantharidin resistance gene 1 (Crg1). Recent findings suggest that 
CAN exerts its toxic effects by perturbing lipid homeostasis and targeting Cdc1 mediated 
remodelling in yeast ER. Although we have some knowledge about its mechanism of action, its 
other potential genetic/epigenetic targets remain to be explored. Also, CAN associated drug 
resistance mechanisms which dictates the cytotoxic potential of this drug is yet to be identified.  
Through our present study, we have identified new molecular mechanism(s) behind cantharidin 
mediated cytotoxicity using Saccharomyces cerevisiae as a model organism. Our findings suggest 
yeast cells are sensitive to CAN and external supplementation of ethanolamine (ETA) could 
ameliorate this cytotoxicity. Further, cantharidin downregulates phosphatidylserine 
decarboxylase1(PSD1) expression which in turn affects the cellular PE pool. We show cantharidin 
inhibits autophagic flux and external administration of ETA could rescue this inhibition. Next, we 
investigated CAN associated drug resistance mechanisms which dictates the efficacy and cytotoxic 
potential of this drug. To this end, we screened mutants of pleiotropic drug resistance network of 
genes for their susceptibility to CAN. Loss of one of the Pdr1 target genes, PDR5, encoding an ABC 
membrane efflux pump, rendered the cells hypersensitive whereas overexpression of it conferred 
resistance. We also explored the role of histone H3/H4 residues in mediating CAN toxicity. 
Interestingly, mutations in several histone residues caused drastic reductions in CAN drug resistance 
viii 
 
and PDR5 transcription. Collectively, our findings reveal that CAN mediated cytotoxicity in yeast 
occurs via downregulation of PSD1 expression and defects in autophagic flux and Pdr5 serves as a 
major safeguard against this cytotoxicity. 
Keywords: Cantharidin, PSD1, autophagy, stress response, yeast, Kennedy pathway, ABC 
transporter, PDR1, PDR3, histone, gene expression, histone H3/H4, transcription regulation, 
cytotoxicity, Chloroquine 
 
 
 
 
 
 
 
 
 
 
 
 


English

Mechanistic insights into yeast cytotoxic sensitivity to natural anticancer molecule, Cantharidin

BADIGER, CHIDANAND

Preface
The thesis is the outcome of my research work on geometry and topology. This
work is specifically in the field of homotopy theory and theory of vector fields. This
thesis consists of answers to the five research problems that are considered both in
geometry and topology including the homeomorphism problem. The prerequisites are
an elementary knowledge of algebra, analysis, general topology, algebraic topology
and theory of manifolds.
The thesis provides a systematic and comprehensive development in the extension
of the fundamental and higher homotopy group called Core fundamental groupoid and
also a method to obtain left-invariant vector fields on some smooth manifolds which
admits a regular Lie group action. More precisely, we have two main objectives: The
first one in topology is to solve the homeomorphism problem by giving a sufficient
new invariant by extending the theory of homotopy. The second one is to provide a
general method to obtain left-invariant vector fields on some smooth manifolds which
admits an action.
The first objective of obtaining a sufficient invariant is resolved by introducing
Core fundamental groupoid which is a topological groupoid. This leads to study
on covering maps and Core fundamental groupoid, Core fundamental groupoid bun-
dle, section on Core fundamental groupoid bundle and method of obtaining the left-
invariant sections of Core fundamental groupoid of some topological spaces which
admits a regular topological group action. The second one is followed by the succes-
sive group actions on first on a manifold and second on its tangent bundle by a Lie
group and its transformation group on manifold respectively. This thesis has eight
chapters that contain explicitly as contains the following:
The first chapter contains the preliminaries to the entire thesis work. It contains
fundamental notions and basic properties of groups, groupoid, topology, manifolds,
group action, bundles and category.
The second chapter contains a new notion called Core fundamental groupoid. Sec-
tion 2.2 introduces Core fundamental groupoid, it is an extension of the fundamental
iii
group (Poincare group). It is defined by the disjoint union of the fundamental groups
at points of M , and denoted by π̄1M =
⋃
x∈M π1(M,x). Here groupoid is used in al-
gebraic sense, not as a category (Groupoid [81] is a category in which every morphism
is invertible). It is proved that, for a given topological space M , then π̄1M forms a
groupoid. Induced homomorphism is extended to induced groupoid homomorphism
on respective Core fundamental groupoids for a continuous map and thus its similar
kind of properties like induced homomorphism placed in this section. It also contains
induced base map for a groupoid homomorphism T : π1M → π1N and is defined by
a map bT : M → N such that pN ◦ T = bT ◦ pM , and some of basic consequences. It
contains a main result that the fundamental groupoid is a topological invariant but
not sufficient. In the section 2.3 the fundamental groupoid is shown as a topological
groupoid which is a sufficient topological invariant and thereby provides a charac-
terization to the homeomorphism. That is stated in a proposition as “Let M,N be
two topological spaces and f : M → N be a map then f is a homeomorphism if and
only if f# : (π̄1M, IpM ) → (π̄1N, IpN ) is a topological groupoid isomorphism”. Sec-
tion 2.4 contains some categorical view points regarding Core fundamental groupoid
and a new notion of ‘same Core fundamental groupoid type relation’ and also its
application to a characterization to the homeomorphism.
The third chapter contains another new notion called Core higher homotopy
groupoid. Section 3.2 introduces Core higher homotopy groupoid, which is an ex-
tension of the fundamental groupoid and higher homotopy group. It is defined by
the disjoint union of the higher homotopy groups at points of M , and denoted it by
π̄kM =
⋃
x∈M πk(M,x). It is proved that, for a given M a topological space then π̄kM
forms a groupoid for each k ∈ N. Induced homomorphism is extended to induced
groupoid homomorphism on respective Core fundamental groupoids for a continuous
map and thus its similar kind of properties like induced homomorphism are placed
in this section. It also contains induced base map for a groupoid homomorphism
T : πkM → πkN on k-th homotopy groupoids and is defined by a map bT : M → N
such that pN ◦ T = bT ◦ pM , and some of the basic consequences. It contains a main
iv
result that the higher homotopy groupoid is a topological invariant but not sufficient.
In the section 3.3 the higher homotoy groupoid is shown as a topological groupoid
which is a sufficient topological invariant and thereby provides a characterization to
the homeomorphism. That is stated in a proposition as “Let M,N be two topological
spaces, f : M → N be a map and k be a natural number then f is a homeomorphism
if and only if f# : (π̄kM, IpM )→ (π̄kN, IpN ) is a topological groupoid isomorphism”.
Section 3.4 contains some categorical view points regarding Core higher homotopy
groupoid and a new notion of same ‘Core homotopy groupoid type relation’ also its
application to a characterization to the homeomorphism.
The fourth chapter contains study on covering projection and Core fundamental
groupoid. Section 4.2 provides some characterization of the simply connectedness with
the concept of Core fundamental groupoid. It also contain the basic consequences
on induced groupoid homomorphisms of covering projections. Section 4.2 provides
a method of obtaining covering spaces to a connected, locally path-connected, and
semi locally simply connected space and for each wide subgroupoids of it.
The fifth chapter contains a theory of Core fundamental groupoid bundle. It em-
phasizes bundle structure, section and relatedness on sections of a Core fundamental
groupoid bundle of a topological space. It provides explicit description of the bun-
dle, fibre bundle, principal G-bundle structure on the Core fundamental groupoid in
respective cases. Section 5.3 contains sections of Core fundamental groupoid bundle
and pushforword and pullback maps on section space of respective topological spaces
of a homeomorphism. Section 5.4 contains Relatedness on the both homeomorphisms
on space and sections of its Core fundamental groupoid bundle i.e. section related
homeomorphism and homeomorphism section. Rel operation is extensively discussed
in this section and an interrelationship is built between some subgroups of homeomor-
phisms on a space and some subgroups of sections of the Core fundamental groupoid
bundle.
The sixth chapter contains a method of obtaining left-invariant sections of the
Core fundamental groupoid bundle for some topological spaces which admits a regular
v
topological group action.
The seventh chapter contains a method which yields vector fields on some smooth
manifolds. A method is introduced to obtain left-invariant smooth vector fields on
some smooth manifolds which admits a regular Lie action. This sections also con-
tain results on support and smooth frame on such manifolds. Section 7.3 contains
Relatedness on both diffeomorphisms and vector fields on the smooth manifolds i.e.
vector field related diffeomorphisms and diffeomorphism vector fields. Rel operation
is extensively discussed in this section and an interrelationship is built between some
subgroups of homeomorphisms on a manifold and some subspaces of set of all vector
fields on it.
The eight chapter contains some of the important applications that are coming
from the research work carried out in the previous chapters. This section highlights
the classification problem that is classification of spaces up to homeomorphism by
emphasizing a characterization to homeomorphism by Core fundamental groupoid.
Also it highlights some important results placed in the previous chapters. Finally,
section 8.3 provides overall outcomes as a conclusion that explains and concludes our
research work.
It is to be note that, we have used the notation µ or µi for i = 1, 2 for group
action in all most all the chapters. Therefore, consider them and their consequences
in the respective chapters independently.
vi


SOME PROBLEMS IN GEOMETRY AND TOPOLOGY

Gakhar, Teena

viii 
 
Abstract 
Volatile organic compound (VOCs) being virulent, noxious and carcinogenic critically threaten 
the human health and ecological environment. This work primarily aims at the development of 
carbon-metal oxide nanocomposites based devices for the detection of VOCs. The work was 
carried by the development of two different types of nanostructures of TiO2 having opposite 
type of conductivity.  First, 1-D TiO2 nanotubes were developed by electrochemical 
anodization which exhibited n-type behaviour. Secondly undoped TiO2 nanoparticles were 
synthesized by sol gel method which exhibited p-type behaviour. Both the pure TiO2 
nanostructures were thoroughly studied and further utilized for the formation of 
nanocomposites with different nanoforms of carbon. Two different nanoforms of carbon i.e. 2-
D graphene and 0-D fullerene were considered for the nanocomposite formation with TiO2 
nanostructures. Nanocarbon-TiO2 composites were synthesized by using different techniques 
like hydrothermal, sol gel, and electrochemical anodization etc. Nanocomposites including the 
pure nanoforms were subjected to different characterization techniques to study their 
morphology, chemical composition and structure etc. Oxygen vacancy modulation in TiO2 
nanotubes were performed via two different techniques – cathodic polarization and chemical 
reduction. TiO2 nanotubes reduced by cathodization exhibited a high response magnitude of 
90 % to 100 ppm of ethanol at 150 ̊ C. Whereas the chemically reduced TiO2 nanotubes showed 
a moderate response magnitude of 75.4 % at 150 ˚C. These reduced TiO2 nanotubes sensors 
having vertical structure offered a dynamic range to detection from 20 ppm to 200 ppm 
selectively towards ethanol. 
Different device structures were fabricated for efficient VOC sensing. Three different device 
structures were proposed according the three different nanostructures ̴ 0-D,1-D and 2-D. The 
0-D nanostructures (nanoparticles) were implemented in planar structured device. The 1-D 
nanostructures (nanotubes) were implemented in Metal Insulator Metal (MIM) sandwiched 
structured device. The 2-D nanostructures were implemented in field effect transistor (FET) 
type device structure. FET device structure was preferred in back gate structure to keep the 
sensing surface exposed to the ambient.  The proposed device structures were well suited for 
the synthesized nanoforms.  
Two types of GO-TiO2 nanostructures composites were fabricated which offered promising 
sensor performance towards alcohols. GO-TiO2 nanotube composite depicted room 
temperature methanol sensing with good response magnitude (28 %) and fair 
response/recovery time (34 s/40 s).  GO-p-TiO2 nanoparticle composite based back gated FET 
ix 
 
sensors depicted a high response magnitude (115 %) towards 100 ppm ethanol at 100 ˚C at 
appropriate gate voltage (0.7 V). Moreover, GO-p-TiO2 nanoparticle composite depicted a high 
ION/IOFF ratio of 2.8×10
3,
 with acceptable transconductance of 0.286 µS and high transport gap 
of 54.2 meV at room temperature 
Functionalized fullerene C60-TiO2 nanostructures composite sensors were synthesized which 
were highly sensitive and selective towards formaldehyde. Four C60-TiO2 nanotube composites  
with varied concentration of fullerene (0.006 wt%, 0.01 wt%, 0.02 wt% and 0.05 wt%) were 
synthesized through hydrothermal method. All the MIM structured C60-TiO2 nanotube 
composite sensors showed excellent response magnitude (>92%) to 100 ppm of formaldehyde 
at 150 ˚C.  Sensor having 0.05 wt% of fullerene showed the highest response of 99.6% towards 
100 ppm formaldehyde at 150°C where as sensor having 0.02 wt % of fullerene showed fastest 
response/recovery of 4 s/ 7 s among all the sensors at the same conditions. 
C60 encapsulated TiO2 nanoparticles composite was also synthesized via chemical route by 
using hydrated fullerene-C60 and sol-gel derived undoped p-type TiO2 nanoparticles. The 
planar structured C60 encapsulated TiO2 nanoparticles sensor depicted more than double 
response magnitude (117 %) than the pure TiO2 nanoparticle (48%) and pure C60 particles (40 
%) and appreciably fast response/ recovery (12 s /331 s) towards 100 ppm of formaldehyde at 
150 ˚C. Flow diagram, indicating all the essential steps has been shown below.  
 
 
Fig. ⅰ. A flow chart of complete thesis work 
 


Carbon-TiO2 Nanocomposites based Devices for Detection of Volatile Organic Compounds

Kaur, Jasbir

Study of Algebraic and Combinatorial Properties of Group Rings 
In this thesis conditions have discussed on finite 2 and 3 groups G under which fourth and 
fifth dimension subgroup is trivial. Also, in last Chapter the complete algebraic structure of 
finite semisimple group algebra Fq[G] has been obtained, where Fq is a finite field with q 
elements and G is a finite group such that G/Z(G) is isomorphic to direct product of two 
cyclic groups of order p, p odd prime 


Study of Algebraic and Combinatorial Properties of Group Rings

Gupta, Ashima

vi 
 
ABSTRACT 
With the advancement of the integrated circuit (IC) industry, there is a growing demand for 
battery-powered and low-power devices for portable applications in consumer electronics, 
medical science, communication, and automatic vehicles, etc. In mixed-signal circuits, 
analog circuits are about 20% in portion but consume 80% of the design time and effort, and 
have higher power, process variations and interference, whereas digital circuits are power 
efficient, robust, and require less design effort; thus, less time-to-market, has less process, 
voltage and temperature (PVT) variations and scalable. A methodology for designing 
analog/mixed signal circuits employing digital-in-concept circuits has been proposed in the 
present work. A flash ADC has been chosen to demonstrate this digital-in-concept circuit 
design methodology for SoC applications such as autonomous navigation, collision 
avoidance, distance measuring, and robot ranging sensor. A voltage reference ladder, 
comparators, and an encoder are the three basic components of a flash ADC. Due to the 
analog nature of the comparators and voltage reference ladder, which form the basic analog 
building blocks of the flash ADC, were redesigned using digital-in-concept circuits. 
Different versions of digital-based analog comparators (pseudo comparators) have been 
proposed to operate across the entire input range. The proposed pseudo comparators have a 
power dissipation ranging from 75 µW to 196 µW, an offset voltage of less than 4.97 mV, a 
maximum delay of 2.9 ns and a FOM of 1.2 fJ/conv. To test the functionality, some of the 
proposed comparators have been implemented on FPGA. Further, fully-digital and 
synthesizable analog comparators have been proposed. The post layout simulations of the 
proposed synthesizable voltage comparator show offset, delay and power of 0.72 mV, 0.532 
ns and 269.8 µW, respectively and the physical layout area is 728 µm2.  
A novel digital-in-concept voltage reference ladder, consisting of a delay-based network and 
a time-to-voltage converter has been presented. It operates in the range of 0.46 V to 1.8 V 
with an LSB of about 20 mV and have a negligible process variation in the delay-based 
network.  
The proposed pseudo comparators have been used to implement 4-bit and 5-bit flash ADCs 
with FOMs of 0.81 pJ/conv. and 0.55 pJ/conv., respectively. The all-digital 6-bit flash ADC 
has been implemented using the synthesizable comparator and the digital-in-concept voltage 
vii 
 
reference ladder in 180 nm 1.8 V CMOS SCL technology. The physical layout of chip's core 
occupies an area of 534.53 µm × 301.2 µm and is integrated in a 2 mm × 2 mm die. The 
proposed all-digital 6-bit flash ADC has a FOM of 1.03 pJ/conv. At a sampling frequency of 
400 MHz, the proposed ADC consumes 16.6 mW of power. ENOB, SNDR, SNR, and SFDR 
for this ADC are correspondingly 5.33, 33.8 dB, 35.2 dB, and 39.73 dB. The values of INL 
and DNL are +0.7/−0.2 LSB and ±0.5 LSB, respectively. Hence, the proposed all-digital 
flash ADC is suitable for low power and high speed SoC application with reduced design 
effort time-to-market. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


Design and Analysis of All-Digital Flash Analog-to-Digital Converter

Shaha, Chaitali

PUTATIVE EFFECT OF XENOBIOTICS ON ESTERASES OF 
BACTERIAL FLORA FROM CHIRONOMUS CIRCUMDATUS 
(BLOODWORMS 
 
Chironomids (Diptera: Chironomidae) are the most abundant insects found in freshwater. Daily, 
these insects are exposed to different phthalates as they are used as plasticizers in many plastic 
materials and do not form covalent bond with the polymers therefore being as one of the major 
pollutants in the aquatic habitats and soil. Therefore, in most of the studies evaluations on the 
alterations in the morphology as signs of phthalate toxicity on these Chironomus species have been 
studied, but through our study we tried to research on another aspect of the problem wherein we 
have tried to find out the role of microbiota present in the Chironomus species in helping to adapt to 
these phthalate mediated stress. Chironomus circumdatus are ubiquitously found in almost all Asian 
countries and even in India they are readily available in different aquatic habitats. As they spend 
maximum of their lifespan in larval stages, in the present work, we explored the microbiota of C. 
circumdatus larvae and tried to evaluate the role played by these microorganisms in the host in 
adaptation to phthalate mediated stress. Also, we aim to evaluate the effects of the phthalate 
mediated stress on the esterase activity of bacterial flora found in the C. circumdatus. 
In the first chapter, studies related to metagenomic analysis using next generation sequencing has 
been described which is used to find out the unculturable and culturable bacteria found in the living 
organism. At the genus taxonomic level, 437 taxons were present in the whole larvae of C. 
circumdatus, which included some of the pathogenic as well as useful members of bacterial species. 
In the second chapter, through culture-dependent isolation of bacterial flora, two bacterial isolates 
(BI1244 and BI1245) showed a clearance zone on tributyrin agar plates indicating the presence of 
esterase enzyme within them. Based on molecular characterization, the bacterial strain BI1245 was 
found to be another strain of Enterobacter mori therefore the strain was named as E. mori BI1245. 
Further studies were carried on using the bacterial strain E. mori BI1245. From substrate specificity 
studies, it was observed that the crude extract obtained from E. mori BI1245 had more specific activity 
towards p-nitrophenyl acetate as compared to p-nitrophenyl butyrate and p-nitrophenyl palmitate 
indicating that it possesses more of esterase activity. Maximum crude activity was observed at pH 8 
and at 60ºC with p-nitrophenyl acetate as substrate. 
In the third chapter through experiments it was found that bacterial isolate BI1245 could grow fast in 
the culture medium added with shorter alkyl-chains phthalate esters such as diethyl phthalate, dibutyl 
phthalate than in that with longer alkyl-chains dioctyl phthalate, indicating that the side chain of the 
substrates has a significant effect on the utilization pattern of phthalic acid ester by the bacterial 
isolate. Characterization of esterases from the crude extracts obtained from diethyl, dibutyl and 
dioctyl phthalates was also done. The crude extracts samples showed high activity towards p-
nitrophenyl acetate as compared to p-nitrophenyl butyrate and p-nitrophenyl palmitate indicating 
that the crude extracts had high esterases activity. The order of affinity of crude extracts towards 
substrate p-nitrophenyl acetate based on Km values was as follows: diethyl phthalate > dibutyl 
phthalate > dioctyl phthalate. Degradation was studied by using the first-order kinetics for dibutyl 
phthalate, diethyl phthalate and dioctyl phthalate by using high performance liquid chromatography 
and gas chromatography mass spectrometry. 
In the fourth chapter expression studies of enzymes carboxylesterases (carEW), dialkyl phthalate ester 
hydrolase (dpeBH), monoalkyl phthalate ester hydrolase (mpeH) and phthalate 4, 5- dioxygenase (oph 
A1) genes was carried out wherein it was found that in dibutyl phthalate sample, gene expression of 
CarEW and oph A1 was seen, while in 
the diethyl and dioctyl phthalate sample, along with CarEW and oph A1, expression of mpeH gene was 
also seen. Thus it can be hypothesized that enzyme carboxylesterases is capable of hydrolyzing diethyl 
phthalate, dibutyl phthalate and dioctyl phthalate to phthalic acid while phthalate 4, 5- dioxygenase 
enzyme catalyzes the incorporation of two hydroxyl groups on the phthalate ring to yield phthalate 
dihydrodiols and initiates the process of biodegradation of phthalate into smaller compounds. Thus 
the study done gives us preliminary insights that the bacterial strain E. mori BI1245 can completely 
mineralize the diethyl, dibutyl, and dioctyl phthalates to smaller compounds. Present investigation is 
important for the bioremediation of widespread environmental pollution caused by phthalates. 


PUTATIVE EFFECT OF XENOBIOTICS ON ESTERASES OF BACTERIAL FLORA FROM CHIRONOMUS CIRCUMDATUS (BLOODWORMS)

Karmakar, Akashdip

Undetermined

Studies on scattering of charged particles in plasmas

-, Rahul

viii 
 
ABSTRACT 
1. Introduction 
Bridges are structures constructed over a body of water like a river, stream, valley, or a 
road for the purpose of providing passage over the obstacle. Bridges are essential for the 
transfer of people and goods from one place to the other.  Construction of bridges across a 
river partially obstructs the flow path and modifies the geometry and velocity of flow. In 
the field of hydraulic engineering and its associated fields, sediment transport, 
degradation and deformation of the riverbed, scouring and flooding are considered 
significant issues. Out of these issues, scouring around bridge piers is a crucial area of 
interest to hydraulic engineers and designers. Past studies indicate that scouring around 
bridge elements is a major factor in the failures of bridges. 
2. Literature 
According to Melville (1975), three factors are mainly responsible for the change in bed 
elevation around the bridge piers. One, due to progressive aggradation and degradation of 
sediment particles, two, due to temporary scour due to change in bed level of the river 
and three, due to an obstruction, such as a bridge pier, which obstructs the flow. Scour 
around an obstruction like a bridge pier is a local phenomenon arising out of the three-
dimensional separation of flow upstream of the obstruction giving rise to a horseshoe 
vortex system. The process commences with a three-dimensional separation of flow on 
the upstream front of the pier owing to an adverse pressure gradient. This separation 
results in the formation of a vortex in a vertical plane which wraps around the pier at the 
sediment-pier interaction junction and looks like a horseshoe in plan. This horseshoe 
vortex system is responsible for scraping the material from upstream of the pier and 
releasing it in suspension at the rear of the pier, thus causing scouring around the pier, 
Setia (1997).  
 In the past about half a century, numerous investigations have been recorded on the 
bridge failures to understand the process of scouring around the single bridge pier. 
Breusers et al. (1977), Chiew (1984), Breusers and Raudkivi (1991), Garde and 
Rangaraju (1992a), Gangadharaiah et al. (2012), and others. These researchers have 
studied and explained the phenomenon of scouring around a single bridge pier. Further, 
studies have also been conducted on the estimation of scour depth around a pier and its 
ix 
 
prevention. But due to rapid urbanization more and more bridges are being constructed in 
close proximity of each other which have an interference effect on each other. Not much 
work has been done on the possible when the interference of such bridges which are 
present at very close proximity. Few researchers, mainly Hannah (1978), Parsad (1993), 
Beg (2002), Movahedi et al. (2013) Khaple et al. (2014) and Ali et al. (2017) have 
initiated work around different arrangements and groups of piers. Further, there is a large 
variation in the use of different parameters adopted for experimentation. That makes it 
difficult to generalize the results obtained through such experiments. Thus, the 
interference study around bridge piers is in underdeveloped stage and works in the 
laboratory as well as in the field are required to be directed and planned towards such 
studies. The present study is one such study in this direction. The main objectives of this 
experimental research were to analyse the mechanism of flow in the presence of some 
interfering geometries and to determine the effect of varying parameters on the scour 
depth around such groups of piers and units. 
3. Scheme of experimentation 
A laboratory study had been planned and conducted to investigate the interference effects 
of various piers in different geometries, and interference of pipelines and groynes with a 
pier. The experimental study was carried out on a mobile as well as rigid bed in the 
Hydraulic Laboratory of Civil Engineering Department at the National Institute of 
Technology Kurukshetra, India. Three different types of flumes were used for the 
experimental study. In this thesis, the flumes were denoted by Flume A, Flume B and 
Flume C. Flume A is 12m long, 0.60m wide and 0.70m high. The working section of the 
flume, which is 2m long, 0.6m wide and 0.24m deep, was located at 5m downstream 
from the inlet section. The working section was filled with fine sand having a mean size, 
d50 = 0.23mm. Flume B had nominal dimensions of 15m length, 0.40m width and 0.60m 
height. The side walls of the flume are made of Perspex to easily visualize the flow 
around the bridge piers. An outlet tank has been provided at the end of the flume for 
collecting the water. Flume C is a standard recirculating tilting bed water flume with 
nominal dimensions 5 m long, 0.25 m wide and 0.305 m deep. Flume C has been used to 
study the behavior of flowing water on the surface with the help of ‘Aluminium paint 
technique’ and ‘Wet paint technique’.  
Three types of the sediments, with mean size d50 0.23mm, 0.30mm and 0.50mm were 
used to perform the experimental work. However, majority of the work had been 
x 
 
conducted on the sediment size 0.23mm.For this sediment geometric standard deviation, 
the coefficient of uniformity and the coefficient of curvature was 1.5, 1.3 and 0.88, 
respectively.  
Two sizes of circular piers having diameters 62mm, 42mm besides an oblong pier of 
frontal size 62mm and length 22cm were used. A group of piles of diameter 25mm each, 
a pipeline of 62mm diameter and a thin groyne of 11cm were the other models used 
during the study. The velocity of flow for those experiments involving uniform flow was 
maintained such that it was close to the incipient conditions. Guided by literature, the 
depth of flow was maintained such that its effect was negligible. Duration of each run for 
the uniform flow experiment was 300 minutes. The maximum scour depth observed 
during this time was recorded for reporting and comparison. 
Flow parameter comprising of type of flow, velocity and depth of flow and duration of 
test run was maintained similar throughout the study for the case of experiments under 
clear water scour condition. Some experiments were conducted under unsteady flow 
conditions, combining clear water and live bed scour in the form of a single-peaked 
hydrograph. In these cases, the discharge was increased in four steps of small-time 
durations and then decreased in the next three steps.  
Besides the mobile bed, experiments were also carried out on a rigid bed to understand 
the mechanism and behaviour of flow in the presence of different arrangements of piers. 
• Rigid bed  
Three different techniques namely 
(i) Dry silver paint technique 
(ii) Wet paint technique 
(iii) ANSYS 17.2 and 18.0 (Swanson Analysis System) 
were used to study the physics of flow and its modification. 
• Mobile bed 
Experiments on mobile beds were carried out under four categories of piers and other 
appurtenances: 
a) Tandem arrangement, two or more equal or unequal diameter of piers in a line  
  along the direction of flow. 
b) Two piers in ‘Side by Side’ arrangement, 90˚ to the direction of flow 
xi 
 
c) Three piers in a ‘Staggered’ arrangement  
d) Other arrangements. 
(i) A group of piles in different arrangements, with and without pier 
(ii) A pipeline and a pier 
(iii) A groynes and a pier 
Modelling Analysis 
Two methods, namely Artificial Neural Network (ANN) and Regression Forest Tree (RF) 
were used for the analysis of the experimental results.  
• ANN is a data handling framework that is analogous to the neural networks in living 
organisms both structurally and functionally. It aims at yielding relevant outputs for 
some given inputs processing the input as a black-box. Neural systems are prepared 
for different parameters to involve in the phenomena and relate to the weights 
provided to them. The neural network comprises of neurons which connected 
mutually through weight components that are ultimately used for the comparison of 
certain predictions and the actual parameters based on the adjustment of these 
weights.  
• Random Forest Tree is a suite of learning methods used for classification, regression 
and other tasks. The suite operates by constructing an array of decision trees at the 
time of training and resulting into outputs in the form of classes (classification) or 
mean prediction (regression) of the trees at an individual level. Random forests are 
used to naturally prioritize variables in a regression or classification problems as 
well. 
4. Results, Analysis and Discussion 
The results, their analysis and discussion has been dealt with in five chapters covering 
both, the studies on a rigid bed and the mobile beds.  
4.1 Mechanism of interference studies (Rigid Bed) 
In order to study the mechanisms involved in the case of groups of piles or piers, a series 
of experiments was performed with the help of two transparent cylindrical glass piers of 
diameter 62mm each. The cylindrical pier models were placed in different orientations 
and the flow modification was observed with the help of the techniques described earlier. 
a) Tandem arrangement 
In the tandem arrangement it was observed that the flow approaching the front pier gets 
xii 
 
divided and move on from the sides of the pier. It creats its wake zone on the downstream 
of the front pier and as it tends to converge, it encounters the sides of the rear pier and 
once again diverges. The formation of eddies and swirls is more easily visible. Thus, the 
zone falling in between the two piers when they are very close to each other is protected 
from the direct attack of flow.In other words, the downstream pier is completely protected 
or shielded in this position. However, when the spacing between the two piers increases, 
the downstream pier also faces the flow which enters the wake zone of the front pier. The 
arrangement exhibited the mechanisms of ‘Shielding’as also explained by Hannah (1978). 
b) Side by Side arrangement 
Inthe side by side arrangement whenthe spacing between the two piers was zero, the two 
piers were touching each other shoulder to shoulder. By defination, there was no flow 
taking place between them and it was as if it was a single pier with size 2D. As expected, 
the dry paint which was sprinkled on the upstream of the unit  was moving past the piers 
and was creating a large wake zone on its downstream.This unit of two piers had a single 
but larger horse shoe vortex wrapping around the combined unit. When the spacing 
between the piers kept was 1.5 times the diameter of the pier. It showed two horseshoe 
vortices wrapping around each of the two piers. These two individual horse-shoe vortices 
were smaller in size in comparison to the previous discussed case and theirarms were 
getting compressed as they competed to enter the space between the two piers. The 
‘compression of the horse-shoe vortices’ was very conspicous at smaller inter pier 
spacing. At the same time the outer arms of the horseshoe vortex exhibited shedding of 
the vortices. 
c) Staggered arrangement 
In order to study the mechanism involved in this type of geometry of three piers, two 
staggered arrangements of spacing, S equal to zero and 2.5 times the diameter of the pier 
had been tried. When the three piers are touching each other, their centers when joined 
together, make an equilateral triangle of sides 1D. Now size of the obstruction facing the 
flow is equal to twice the diameter of the pier. For the front portion of this arrangement it 
is the same as the side-by-side arrangement with zero spacing. The flow can be observed 
to be traversing from the outside of the two front piers and forming a large single 
horseshoe vortex. The wake zone created at the downstream of the arrangement is also 
larger in comparison to the wake zone of a single pier. The converging of the wake zone 
is not occurring immediately after passing the two piers as there is another pier forming 
xiii 
 
an extension of this obstruction. This arrangement of three piers in a staggered pattern 
showed the mechanics of compression of the horseshoe vortices, shedding of vortices. 
While the effect of ‘reinforcing’ could not be established with these techniques, the effect 
of ‘shielding’ was certainly absent. 
 The pictorial views obtained with the aid of ANSYS 17.2 and 18.0, gave information 
of velocity vectors, streamlines and velocity contours. This was used to have an insight 
into the mechanism. The results indicated that the mechanism of flow around groups of 
piers is much different as compare to the mechanism of flow around an isolated pier. 
4.2 Mobile bed studies 
The phenomena were collaborated with a series of experiments conducted on a mobile 
bed of different grades of sediment. 
a) Tandem arrangement 
In the tandem arrangement, it was observed that for all values of T/D = 16 that were 
experimented upon; the scour depth at the upstream pier was more than that of the 
downstream pier. When the two piers are attached to each other or the spacing between 
the piers is zero, it is analogous to the case of a single pier and the scour depth is also 
same. As the spacing shifts to one time the diameter of the pier, the downstream pier also 
registers its own scour depth. Individually, the scour at upstream pier shows a rising trend 
up to a T/D of 4, beyond which it shows a gradually decreasing trend. Interestingly, the 
scour depth at T/D = 0 and T/D = 16 are the same at the upstream pier. With increasing 
(T/D), initially, the downstream pier shows more scour depth. But when (T/D > 4) times, 
it shows a decrease in scour depth. In the initial stage, when the spacing (T/D) between 
the piers increases from 0 to 8 times the diameter of the pier, then the scour depth is very 
high and reaches up-to maximum and after that when T/D> 10, it decreases. At T/D >10 
the scour depth becomes constant.  
 The shed vertices from the shielding pier tend to deposit the sediment on the 
downstream of it (front pier). In this case, the deposition is taking place on the upstream 
of the downstream pier. Thus, with the downstream pier also causing scour of its own, 
does not allow the sediment to deposit in front of it and thus act as a conveyor belt and 
the upstream pier has to experience more scour.  
This arrangement verifies the two mechanisms of ‘shielding’ and ‘reinforcing’. The 
increase in scour depth of u/s pier in the presence of a d/s pier exhibits the conveyor belt 
phenomenon. 
xiv 
 
b) Side by side arrangement 
In the side by side arrangement, at zero spacing, the two individual piers join together to 
form a single united obstruction and yield a high value of scour equal to 2D. In terms of 
the scour depth of an individual pier of size D, the scour depth at this stage is 1.66 times. 
Infect, the combined unit shows a common scour hole. When the spacing between the 
piers was one time the diameter, the scour depth dropped to 0.9 and 0.85 times the scour 
depth of the zero spacing position, for the left and right piers, respectively. 
 For the present experimentation, the maximum spacing tried was 4D at which the 
scour depths for the left and right piers were 1.08 times and 1.10 times that of the scour of 
an individual pier. Taking the zero spacing as the reference, it was equal to 0.65 to 0.66 
times. Furthermore, a semi empirical equation in the form of Deq is developed to predict 
the maximum scour depth as a function of the spacing between two bridge Piers. This 
arrangement also verified the mechanism of compression of the inner arms of developed 
around the two piers in close proximity of the ‘side by side’ arrangement. This 
compression generates higher velocity thus resulting in higher scour depth. 
c) Staggered arrangement 
Experiments in the staggered arrangement were conducted for two orientations, ie. A 
triangular geometry of three piers, once it was the single pier facing the flow first and 
then it was the two piers facing the flow first. In the latter geometry of staggered 
arrangement, it was observed that the arrangement experienced the maximum scour depth 
when spacing between the piers is zero. It is easy to perceive that in this geometry the 
size of the unit has enlarged and now the effective size facing the flow is 2D. There is 
only a single horseshoe vortex system formed at this stage. Thereafter, as the spacing S 
increases, the scour depth decreases. The decrease in scour depth is because the flow is 
now not fully blocked and its pressure difference becomes favorable between the piers in 
the spacing region. In the former arrangement shedding of vortices of the front pier 
combines with the activity of the rear piers and the sediment from the front pier is likely 
to be conveyed to its rear and to the rear of the rear piers. In that arrangement, all the 
three piers are generally having a decreasing trend of scour depth. The slope of the 
decreasing trend of scour of the front pier was high. At a spacing close to 4 and above, 
the front pier starts showing the scour associated with a single pier. Furthermore, a semi 
empirical equation in the form of Deq is developed to predict the maximum scour depth as 
a function of the spacing between the three bridge piers. The staggered arrangements 
xv 
 
exhibit the mechanisms of compression of the horseshoe vortices and shedding of 
vortices besides showing partial existence of the reinforcing effect. In all the three 
arrangements, the phenomena were corroborated with the help of ANSYS 17.2 and 18.0. 
d) Miscellaneous arrangements 
Under this category group of five arrangements namely, a row with three piles equilateral 
triangle with three piles, equilateral triangle with five piles, an arc with five piles and 
staggered arrangement with nine piles in two rows (4+5) were used on the upstream of a 
pier. Out of the five arrangements, an arc of five piles was least effective and shows the 
maximum scour depth (1.04D) at the pier and the staggered arrangements with nine piles 
in two rows was most effective and show the minimum scour depth (0.65D).Other 
experiments in this chapter pipeline that has been placed on the upstream side of the 
bridge pier. From the observation it can be concluded that, if the distance between the 
pipeline and bridge pier is small the scour depth was found to be more. After that, when 
the spacing between the piers and pipeline greater than 3 times the diameter of the pier, 
both the pier and pipeline does not affect each other. 
The interaction of a pipeline of diameter 62mm with a pier was also experimented upon 
under uniform and non-uniform flow conditions. 
A groyne with different angular orientations varying from 30∙to 150∙w.r.t the side walls of 
the flume were tried and the effective change in scour at the bridge pier was noted. 
5. Outcomes of the study 
The study, besides filling up the gaps in information has been useful in generating 
laboratory data. It could be helpful to the planners in deciding the suitable sites for the 
bridges and other structures which could otherwise interference and be dangerous to the 
stability of piers. The visualization techniques have been useful in having an insight into 
the modification of flow. 
 
 
 
 
 
 
 


Interference Studies around Bridge Piers

Gupta, Chainika

IDENTIFICATION OF CAUSAL SNPs IN PROMOTER

SEQUENCE OF Co-2 AND DEVELOPMENT OF FUNCTIONAL MARKERS FOR ANTHRACNOSE RESISTANCE IN COMMON BEAN (Phaseolus vulgaris L.)

Upadhyay, Sharad Kumar

Study of Coulomb drag in non- homogeneous dielectric medium 
 
This thesis aims to study the Coulomb drag (CD) phenomena of charge 
carriers in the bilayer system of a non-homogeneous dielectric medium 
(NHDM). Several years ago, a non-homogeneous bilayer state was first 
predicted theoretically, this thesis is based on its discovery and 
exploration. Transport measurements allow for the direct detection of 
the interaction in the Fermi-liquid regime. Furthermore, drag resistivity 
(𝜌𝐷) is an excellent tool for predicting the phase transition, such as out 
of phase of the bilayer quantum state. It expands the phase diagram's 
mapping to include the temperature and density imbalance of the 
planes. For that purpose, a carrier transport model has been formulated 
and implemented using the Boltzmann Transport Equation (BTE) solution 
for the weakly interacting regime, at low-temperature limit, large 
interlayer separation regime and Boltzmann/Ballistic regime.  
 
The net screening between the electron and/or holes is assumed 
short/long range and weakly interactive as the distance between the 
carriers is long. The behavior of charge carriers in the layer is non-
interactive and assumed Fermi-liquid regime, the interaction between 
the interlayer and intralayer is assumed. The effective interlayer 
interaction (net screening) between the charge carriers of the system is 
studied within the model of random phase approximation (RPA). The RPA 
method consists very good and consistent results for the high-density 
regime. At low-density regime exchange and correlation (XC) effects 
become more influenced and impacted, therefore the static local field 
correction (LFC) considering going beyond the RPA method. XC effects 
enhanced the effective interaction and drag resistivity (𝜌𝐷) by assuming 
the static LFC.  
 
The layer width and interlayer distance dependent local form factors 
(LFF) is also obtained from the Poisson equation's solution for a 
multilayer dielectric medium (NHDM). The LFF's impact are key function 
for predicting the inter- and intralayer potential, which explore and 
enhances the 𝜌𝐷 compared to simply measured results of bilayer 
systems. The impacts of LFF are the co-functions of bare inter and 
intralayer potential, which yields the dependency of layer separation and 
dielectric constants of the materials. Generally, the drag resistivity is 
directly proportional to the square of the temperature (T) and dielectric 
constant of the barrier (𝜖), inversely proportional to the third power of 
concentration (n) and the fourth power of interlayer separation (d), may 
be shown as, 𝜌𝐷 =
𝑇2𝜖2
2
𝑛3𝑑4
 for weak interaction, at low-temperature, 
low/high-density and large interlayer separation limit. 
 
Graphene-based fermions are chiral and having linear and quadratic 
dispersion relation. Graphene/GaAs based hybrid bilayer system extract 
more numerical results than bilayer system of 2D-GaAs DQW, cause of 
chiral fermions and having much better effective mass, mobility, and 
density of states (DOS), etc... The carriers in the BLG are massive chiral 
fermions with effective mass 𝑚∗ and a parabolic dispersion relationship 
𝐸𝐹
𝐵𝐿𝐺 =
ℏ2𝑘𝐹
2
2𝑚∗
 around the Dirac points. Where BLG have greater effective 
mass than GaAs layer. Hence BLG/GaAs have enhanced results compared 
to bilayer of GaAs DQW Coulomb drag study of SLG/GaAs hybrid bilayer 
system extracted more better results compare to BLG/GaAs hybrid bilayer 
system. The reason for its size in the monolayer system can largely be 
traced to the vanishing density of states at the Dirac point, implying weak 
screening of the interlayer potential. The carriers in the SLG are massless 
chiral fermions with an effect of the linear dispersion (𝐸𝐹
𝐵𝐿𝐺 = ℏ𝜐𝐹|𝑘|) 
around Dirac points. 


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