Institutional Repository

Scholar@UOC is the primary academic repository of the University of Calicut.

This repository is aimed to collect, preserve and distribute the research output of the members of our University. This is an open access system hosted and managed by the University Library.

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Now showing 1 - 5 of 38

Recent Submissions

A study on the shoal structure interaction and behavioural phenomics of social isolation in zebrafish
(Christ College , Inrinjalakuda, University of Calicut, 2026) Aswathy Sivaraman; Binu Ramachandran
Chronic social isolation is a widely used environmental stress model: however, its behavioural consequences across sexes and levels of social organisation remain insufficiently understood. The present study investigated the effects of prolonged social isolation in zebrafish (Danio rerio) using a multi-level behavioural framework integrating individual assays, stimulus-based social tests. collective shoaling dynamics, dyadic interactions. and descriptive gut microbiome profiling. Open field and light—dark assessments revealed increased locomotor activity and altered anxiety-like responses in isolated fish, with strong bascline sex differences becoming masked under isolation. In three-chamber paradigms, isolation reduced social preference and modified predator- and mirror-induced behaviours in a sex-dependent manner. with partial stress buffering observed in males and reduced buffering efficiency in females. Shoal and dyad analyses demonstrated disrupted spatial cohesion, alignment, and emergent state stability in isolated groups. Descriptive microbiome analysis further indicated sex-specific shifts in gut microbial composition. These findings provide translational insight into how chronic social isolation may contribute to behavioural dysregulation relevant to neurodevelopmental and stress-related conditions.
Synthesis characterization and studies on multicomponent oxide materials based on vanadium pentoxide
(MES Ponnani, University of Calicut, 2026) Sabna, M; Jayaram, P
This study investigates the synthesis and characterization of multi-cation-incorporatedV2O5 compounds, specifically Sb-and Ni-incorporated V2O5, to enhance theirstructural, electronic, and photocatalytic properties for advanced applications inenergy storage, environmental remediation, and antimicrobial therapies. Thecompounds V(1-x)2Ni3xO5-δ, V2-xSb2xO5-δ, and V2-xNi2xSbxO5-δ were synthesized viahigh-temperature solid-state reactions, and their structural integrity and phase stabilitywere confirmed using X-ray diffraction, Raman spectroscopy, and X-rayphotoelectron spectroscopy. These analyses revealed the coexistence of orthorhombicV2O5, monoclinic NiV2O6, and tetragonal SbVO4 phases, with varying degrees oflattice distortion and mixed oxidation states (V4+/V5+, Ni2+/Ni3+, Sb3+/Sb0), whichsignificantly enhanced their defect densities and redox behavior.The incorporation of Sb and Ni ions into the V2O5 lattice altered the materials'electronic properties, including their band gap restructuring, explained with Burstein-Moss effect. These modifications were supported by photoluminescence spectra,which showed defect-induced emissions. The compounds demonstrated substantialimprovements in dielectric properties, with frequency-dependent behavior suitable forenergy storage applications such as capacitors. AC conductivity was enhanced bypolaronic hopping mechanisms, although higher doping concentrations led to areduction in charge mobility due to increased structural defects.The photocatalytic activity of Sb-Ni-V2O5/g-C3N4 heterostructures was significantlyimproved, facilitating efficient visible-light-driven reactions for organic MethyleneBlue dye degradation. The Z-scheme photocatalysts exhibited enhanced chargeseparation, leading to effective generation of reactive oxygen species, crucial forpollutantmineralization.Additionally,theSb-Ni-V-Ocompoundsandheterostructures displayed broad-spectrum antimicrobial activity, inhibiting bothGram-positive and Gram-negative bacteria and fungal strains, attributed to oxidativestress and membrane disruption. Overall, the incorporation of Sb and Ni into V2O5yields multi-functional materials with enhanced electronic, photocatalytic, andantimicrobial properties, paving the way for their application in energy storagedevices, environmental remediation, and biomedical fields. Future research shouldfocus on optimizing dopant concentrations, exploring their use in energy storageapplications, and assessing their cytotoxicity for potential biomedical use.
Unravelling the adaptive mechanisms of Alternanthera Tenella colla to heavy metal stress through physiological biochemical and molecular analyses
(Sri NeelakandaGovt. Sanskrit College, University of Calicut, 2025) Firdous, K A; Resmi, M S
Industrial development has resulted in widespread heavy metal contamination across ecosystems and pose serious risks to biodiversity, plant and human health. Despite this, the phytoremediation potential of riparian vegetation in industrial zones remains underexplored. The present study was conducted to identify a potential phytoremediator and to investigate its adaptive mechanisms in response to heavy metal stress. The study was conducted in three interconnected chapters, each addressing a specific aspect of heavy metal tolerance and detoxification. The first chapter focused on the phytosociological assessment of riparian vegetation in the industrial zone of Kanjikode along Walayar Riverbank to identify potential phytoremediators of heavy metal contamination. A total of 97 species belonging to 32 families were recorded, with Poaceae and Asteraceae being the most dominant. Therophytes were prevalent indicating their ability to survive in disturbed environments. Among the flora, invasive species such as Alternanthera tenella, Persicaria barbata and Croton bonplandianus showed high abundance. A. tenella emerged as dominant based on its Importance Value Index (IVI), wide distribution and high efficiency to accumulate and translocate heavy metals like chromium and zinc, demonstrating its strong phytoremediation potential. These characteristics make it a promising candidate for phytoremediation in contaminated riparian areas. The second chapter involved hydroponic studies to evaluate the morphological, anatomical, physiological and biochemical responses of A. tenella to cadmium (Cd), chromium (Cr) and lead (Pb) exposure. Rooted plants were treated with Cd (170 µM), Cr (240 µM) and Pb (680 µM) in Hoagland nutrient medium. Morphological assessments revealed gradual reductions in root and shoot growth, leaf area and biomass under heavy metal stress. Cr caused relatively higher inhibitory effects compared to Cd and Pb. Anatomical observations showed adaptive modifications such as thickened xylem walls, reduced xylem diameter and deposition of electron dense granules in cortical and vascular tissues. These changes indicate metal sequestration and restricted translocation of metals to aerial parts. Physiological analyses exhibited significant decline in photosynthetic pigments, stomatal conductance, and water content. Antioxidant enzymes and stress metabolites like proline and phenol were accumulated under heavy metal exposure, indicating activation of reactive oxygen species scavenging and osmotic adjustment. FTIR spectral shifts confirmed metal binding with functional groups such as hydroxyl, carboxyl, and amide groups in the plant tissues. A comparison of biomass, root- shoot distribution and metal accumulation potential indicated that A. tenella possesses high bioconcentration and bioaccumulation factors. This reflects the plant’s selective accumulation of Cd and Pb in roots (phytostabilization) and efficient Cr translocation to shoots (phytoextraction). Among the three heavy metals tested, chromium triggered the strongest transcriptional and metabolic changes in A. tenella. This led to a detailed transcriptomic and metabolomic profiling presented in chapter three. Metabolomic analysis showed significant accumulation of flavonoids, organic acids, amino acids, polyols, and fatty acids, which likely contribute to metal chelation, oxidative stress mitigation, and maintenance of redox balance. Transcriptomic profiling revealed the upregulation of genes associated with metal transport, chelation, antioxidant defence, and stress signalling and downregulation of photosynthetic and cell wall remodelling genes. RT-PCR validation of eight selected genes across leaves, stems, and roots supported these results. A strong induction of HIPP39, ABCC2, GST, YSL1, and PCS was observed in roots and leaves, while XTH, LAC6, and CASP were downregulated under prolonged Cr exposure. Together, these findings offer better understanding of the molecular and physiological basis of Cr tolerance in A. tenella and understanding of plant-metal interactions. The ability of A. tenella for chromium phytoextraction and its ecological dominance in polluted riparian habitats makes it a promising species for phytoremediation and ecosystem restoration.
A statistical and analytical exploration of some generalized queueing systems with phase type distribution
(Department of Statistics, University of Calicut, 2026) Salima, P; Manoharan, M
Queueing systems with vacation policies effectively model service systems where servers may be temporarily unavailable due to rest, maintenance, or operational interruptions. These manufacturing, models computer are widely systems, and applicable in service communication networks, industries. Incorporating vacation mechanisms enhances realism and allows for better performance analysis, making such models critical for understanding and improving real world service systems. This thesis presents a comprehensive analytical and inferential investigation of single server queueing models with phase-type service and vacation time distributions. A Geo/PH/1 queue with multiple adaptive vacations is analyzed in discrete time, while an M/PH/1 queue with random vacations is examined in continuous time. Phase-type distributions provide flexibility while retaining analytical tractability. Both classical and Bayesian inference approaches are developed for parameter estimation. Classical inference is performed using maximum likelihood estimation via the expectation–maximization algorithm, while Bayesian inference is carried out using Markov chain Monte Carlo techniques with Gibbs sampling. Sensitivity analysis is conducted to assess the robustness of Bayesian estimates. Numerical investigations based on simulated data, along with real data applications, validate the analytical results. Key performance measures, including system utilization, queue length, waiting time, and busy period, are evaluated to demonstrate the impact of vacation policies. The thesis concludes by emphasizing the importance of vacation queueing models in practical service systems and by providing meaningful insights and directions for future research. Keywords: Vacation queueing models, Phase-type distributions, Discrete and continuous time queues, Performance measures, Maximum likelihood estimation, Bayesian inference.
Data analysis of common dyslipidemias for better clinical interpretation calculations of reference or cut off levels and relative prevalence
(Amala Cancer Research Centre, 2026) Shaima C M; Jose Jacob
Dyslipidemias are characterized by abnormal concentrations of cholesterol and triglycerides in plasma lipoproteins, typically resulting from disorders in lipoprotein metabolism. In this study, we are collecting clinical biochemistry data related to dyslipidemia from hospital. The data are analyzed and interpreted clinically by dividing them into gender and age-specific groups. This partitioning helps determine (a) proportion of patients with abnormal lipid profile, (b) gender-based differences, (c) reference intervals, and (d) the distribution patterns among the various subgroups. Lipid profiles were categorized into normal, isolated increases or decreases, and combined increases or decreases of four lipid components: serum triglycerides, total cholesterol, LDL-cholesterol, and HDL- Cholesterol. Our analysis includes assessing correlations, distributions, and variance to establish reference levels and the relative prevalence of common dyslipidemias observed in this hospital population. Data analyses of 15,603 lipid profile samples were done. Out of total 15,603 samples; there were 97 male samples and 86 female samples <18 years of age. There were 369 samples between age group 18 – 25 years. Out of which, there were 210 male samples and 159 female samples. The number of samples between 26 – 50 years was 5168. Out of which, there were 3247 male samples and 1921 female samples in the age group 26 – 50 years. The number of samples in age group >50 years was 9883. Out of which, there were 5925 male samples and 3958 female samples. Approximately 84% of general population in age group between 26 – 50 years, covered in this study have abnormalities in at least one of the lipid profile parameters analyzed. Most prevalent dyslipidemia is Isolated HDL- C decrease in males and females of all age groups except 26 – 50 years. In 26 – 50 years males, the most prevalent dyslipidemia is Isolated Serum triglyceride increase. But in females, Combined LDL-C and Total Cholesterol increase is the most prevalent dyslipidemia. Triglycerides >885mg/dL is the rare form of dyslipidemia. The proportion of patients with dyslipidemia is highest in males of 26 – 50 years. The healthiest lipid profile was observed in the age group females <18years. The study employed statistical and graphical methods, including Histograms, Box-Whisker plots, and Normal Q-Q plots, to analyze and classify lipid profile parameters such as Total Cholesterol (TC), Serum Triglycerides (TG), HDL Cholesterol (HDL-C), and LDL Cholesterol (LDL–C). Histograms and Normal Q-Q plots revealed a positive skew in Total Cholesterol and Triglyceride distributions, and Box-Whisker plots helped identify outliers, which were furthercategorized into near and far outliers. These graphical tools were used not only for statistical interpretation but also to clinically differentiate common, multifactorial dyslipidemias from rare, severe monogenic forms. Correlation analysis showed that triglycerides positively correlated with glucose, Total Cholesterol, LDL–C, TSH, and BMI in adult males. While in females, Triglycerides positively associated with liver enzymes AST and ALKP, possibly due to sex-related hormonal differences. Triglyceride was inversely correlated with HDL – C in both sexes. Total Cholesterol positively correlated with LDL–C. The reference intervals for various lipid profile analytes across different gender and age groups were analysed. Due to the positive skewness of the data, the 90% reference interval calculation was deemed the most appropriate. For example, In female individuals aged 18 to 25 years, the 90% reference interval values were as: Total Cholesterol: 119.83 mg/dL (lower limit) to 235.55 mg/dL (upper limit); Serum Triglycerides: 32.75 mg/dL to 170.67 mg/dL; LDL Cholesterol: 62.08 mg/dL to 149.35 mg/dL; HDL Cholesterol: 23.59 mg/dL and 61.23 mg/dL These values reflect the range within which 90% of the population in this subgroup is expected to fall. We had collected second set of fasting, 2-hr post breakfast and 2-hr post lunch blood samples (n=312) from healthy individuals of various age groups. Samples were analysed by partitioning and by comparing fasting, 2-hr post breakfast and 2-hr post lunch lipid data. Regarding fasting versus postprandial measurements, Total Cholesterol showed no significant difference, there were Significant mean difference between fasting and post lunch Serum triglyceride in all gender-age groups. HDL-C showed no significant variation with meal timing, whereas LDL-C demonstrated significant changes in both sexes aged 26–50 years. The study underlines the importance of age- and gender-specific reference ranges and shows how graphical and statistical techniques can effectively classify and analyse lipid disorders.