St. Stephens College
Recent publications
Heavy metals and plastic pollutants are the two most disastrous challenges to the environment requiring immediate actions. In this work, a techno-commercially feasible approach to address both challenges is presented, where a waste polypropylene (PP) based reversible sensor is produced to selectively detect copper ions (Cu2+) in blood and water from different sources. The waste PP-based sensor was fabricated in the form of an emulsion-templated porous scaffold decorated with benzothiazolinium spiropyran (BTS), which produced a reddish colour upon exposure to Cu2+. The presence of Cu2+ was checked by naked eye, UV-Vis spectroscopy, and DC (Direct Current) probe station by measuring the current where the sensor's performance remained unaffected while analysing blood, water from different sources, and acidic or basic environment. The sensor exhibited 1.3 ppm as the limit of detection value in agreement with the WHO recommendations. The reversible nature of the sensor was determined by cyclic exposure of the sensor towards visible light turning it from coloured to colourless within 5 min and regenerated the sensor for the subsequent analysis. The reversibility of the sensor through exchange between Cu2+- Cu+ was confirmed by XPS analysis. A resettable and multi-readout INHIBIT logic gate was proposed for the sensor using Cu2+ and visible light as the inputs and colour change, reflectance band and current as the output. The cost-effective sensor enabled rapid detection of the presence of Cu2+ in both water and complex biological samples such as blood. While the approach developed in this study provides a unique opportunity to address the environmental burden of plastic waste management, it also allows for the possible valorization of plastics for use in enormous value-added applications.
The availability of appropriate research corpora is a fundamental concern in music information retrieval research. This paper addresses the design, development, and evaluation of a poetic corpus, POMET, for the meter estimation task. Poems, which communicate through rhythm and apparent meaning, have a vital role in many literary traditions. Metrical rhythm generally involves periodic arrangements of sequences of stressed and unstressed syllables in each line of poems. It has already been proved that poetry’s aesthetic and emotional perception can be studied well using poetic meter analysis. A corpus with eight meters is designed and recorded in a studio environment for Malayalam, one of the prominent languages in South India. Using deep neural network architectures, a pilot evaluation is performed with musical texture features and spectrograms. We hope that the corpus can be used as a benchmark dataset for poetic meter estimation, rhythmic analysis, and corpus-based prosody analysis.
The model discussed in this paper provides an efficient mechanism for the selection and allocation of available limited spectra for transmission of heterogeneous data in a network. The data packets (customers), belonging to different classes, arrive according to a batch marked the Markovian arrival process (BMMAP). The inventory considered is of multi-type (different types of channels becoming available) and are generated according to a marked Markovian arrival process (MMAP). The number of distinct types of inventory and that of the customers are the same. Arriving customers are allowed to wait in finite buffers of each category which are reserved for distinct classes of customers except for the most general class, which is provided with an infinite waiting space. The number of servers also equals the number of distinct types of inventory. When items of a particular type arrive in the inventory, the service starts, providing the buffer of customers of the corresponding class is non-empty. The service can be viewed as a selection process with Coxian distributed service times. The system is analyzed using the matrix analytic method and performance measures are obtained. The model is illustrated with suitable numerical examples.
Drug development is a tedious, expensive and time consuming process that is accompanied with huge amount of uncertainty due to very low success rate using conventional methods. However, in‐silico techniques have helped society in drug designing and repurposing at minimal cost by shortlisting potentially hit compounds from huge libraries in a short span of time. This computational methodology has made a prominent contribution in the virtual screening of therapeutically relevant drugs for various viral diseases. It has helped in providing relevant information regarding drug‐target interaction and mechanism through which we can modify our drug compound for better efficiency. In‐silico tools additionally helps in predicting toxicity and pharmacokinetics, which can further help in clearing trials and approval. The recent outbreak of novel coronavirus (COVID‐19) has resulted in a huge number of deaths and affected the economy of the world adversely. Computational methods have played a major role in shortlisting compounds that can inhibit viral infection by targeting various components of this virus which are essential in spreading the infection and replication mechanism. The repurposing of the drug against coronavirus has become a lot easier and efficient with the advancement in these computational techniques. Hence, this review covers the recent developments in the virtual screening of potentially hit compounds against COVID‐19. The proteins and enzymes of Coronavirus that are responsible for the replication and spreading of infection are targeted using various computational techniques. The potential target structure is subjected to docking and simulations analysis through virtual screening to screen‐out hit compounds from huge drug libraries that can inhibit the infection. A literature review is provided where the promising results of drug repurposing has been shown that helped in reducing both time and cost.
In this present work, a simple chemical co-precipitation method was used to synthesize deoxyribonucleic acid (DNA) capped CuO-NiO bimetallic nanocomposite. The morphology and structure related properties of the samples were analyzed using Energy Dispersive X-Ray Analysis, X-Ray Diffraction, Transmission Electron Microscopy and Scanning Electron Microscopy. Widely used Agar well diffusion method evaluated the antimicrobial activity of the sample. DPPH and FRAP assays were applied to test the antioxidant activity of the sample. Average crystallite size of 16.218 nm NiO and 15.871nm CuO were confirmed within CuO- NiO bimetallic oxide nanoparticles by means of XRD technique. EDAX studies confirmed the purity of the sample. The grain size obtained from TEM studies matches with the XRD results. The free radical scavenging activity of sample was higher in lower concentrations, viz. 0.1, 1, 5 and 10 µg/ml of the sample and activity decreased after that. The IC50 value in FRAP assay shows the potential of this mixed metal oxide nanoparticle in radical scavenging. In agar well cut method, the sample showed moderate antibacterial activity against Mycobacterium smegmatis and Salmonella typhimurium. The results also showed that the CuO-NiO bimetallic nanoparticles are biologically compatible, environmentally benign and economical material having potential applications in biomedical industry.
Soft, flexible and conductive interfaces, which can be used as electrode materials integrated with commercial electronic components and the human body for continuous monitoring of different analytes are in high demand in wearable electronics. In the present work, we explore the development of a functionalized multi-walled carbon nanotube‡‡Functionalized multi-walled carbon nanotube (f-MWCNT). –parafilm§§Parafilm-M (PF). nanocomposite (f-MWCNT–PF) for the fabrication of a flexible electrochemical platform for glucose detection. The f-MWCNT–PF nanocomposite was characterized by transmission electron microscopy, energy dispersive X-ray analysis, Fourier-transform infrared spectroscopy, Raman spectroscopy, and electrochemical techniques. A bioelectrode fabricated by immobilization of glucose oxidase at the f-MWCNT–PF surface was further characterized by atomic force microscopy and tested for glucose. The bioelectrode provides two linear regions of glucose detection: a linear range from 0.08 mM to 3 mM, with a correlation coefficient of 0.982 and a sensitivity of 35.322 μA mM⁻¹; and a linear range from 5 mM to 25 mM, with a correlation coefficient of 0.964 and a sensitivity of 9.346 μA mM⁻¹. The proposed method was successfully applied to measure glucose in blood serum samples, differentiating healthy and diabetic persons. Additionally, the lower detection region could be effectively applicable for glucose sensing in sweat or interstitial fluid samples. The flexible, water-repellant sensing platform can be used as a universal platform for analyte detection, demanding waterproof, conductive platforms for biosensing applications, as it is suitable for protein/enzyme immobilization.
Trace metal concentrations in two species of mysids, Mesopodopsis orientalis and Rhopalophthalmus indicus, from the Cochin estuary, were investigated during the monsoon and pre-monsoon periods. Metal concentration (ppm, dry weight) ranges in mysids during the monsoon and pre-monsoon periods were: Fe (775.75 to 1254.12), Mn (7.85 to 14.57), Co (0.76 to 1.75), Ni (11.19 to 20.00), Cu (20.02 to 47.42), Zn (66.83 to 106.62), Cr (14.30 to 28.45), Cd (0.53 to 1.70) and Pb (7.16 to 14.19). Trace metal bioaccumulation in mysids was found to be species-specific with higher metal concentrations in R. indicus than M. orientalis. Data on trace metal concentrations in mysids are important for environmental forensic investigations, useful for bio-monitoring (i.e., tracing) sources of contaminants (i.e., metal pollutants) and their impacts, and valuable for tracking the dispersal pathways of contaminants in estuarine environments.
Two new species of apseudomorphan tanaidaceans, Pagurapseudopsis kochindica and Ctenapseudes indiana are described as new to science. Specimens used in this study are based on an extensive sampling (79 locations) in the Kochi Backwaters during the Southwest Monsoon and Post-Southwest Monsoon periods. A total of 109 individuals of P. kochindica and 180 individuals of C. indiana were examined. P. kochindica and C. indiana are distinguished from all the known species of their respective congeners by the structure and shape of chelipeds.
Alginate microparticles and nanoparticles crosslinked with Ca⁺² ions are frequently employed in biomedical applications. Here we use microemulsion polymerization to prepare alginate nanoparticles (nanogels) using different crosslinking ions (Ca⁺², Sr⁺², Ba⁺²) to encapsulate a model protein, urease enzyme (jackbeans). With alginate concentrations of 0.2 wt% in the aqueous phase, emulsion droplets showed good stability and narrow, monomodal distributions with radii ∼ 65 ± 10 nm.The size of the nanogel varies with the crosslinking cation and its affinity for the mannunronate and guluronoate units in the linear alginate chain. The nanogels were further characterized using dynamic light scattering, scanning electron microscopy, energy dispersive X-ray spectrometry and zeta potential. This work demonstrates the potential application of Ba-alginate as an alternative matrix for nano-encapsulation of proteins and its use for biomedical applications.
Latonopsis australis is a rare Cladocera inhabiting the entire stretch of the Cochin backwaters, the largest monsoonal estuary along the West Coast of India, during the summer monsoon, but restricted to the upper reaches during the non-monsoon periods. Here, we present the results of an experimental study, which assessed the influence of salinity on the life table demography of the species at different salinity levels. The life table demographic parameters such as net reproduction rate, generation time, intrinsic growth rate, gross reproductive rate, and survivorship of the species were measured in different salinities ranging from freshwater to mesohaline levels (salinity 14). The study showed that higher salinity had a significant negative effect on all life table demography parameters of the species, whereas freshwater to low saline conditions (salinity up to 8) favored the survivorship, life expectancy, net production, and growth rate. It was also noticed that salinity above 8 caused a significant decrease in the survivorship, life expectancy, and reproduction rate of the species, which clearly explained the seasonal distribution pattern of the species in the Cochin backwaters. The present study suggests salinity 2 to 6 as the optimum range for the large-scale production of L. australis for purposes like live feed in aquaculture.
Photoconductivity due to Ultra-violet (UV) rays has been studied in pure ZnO, Au overlayer/ZnO and Au nanodots/ZnO thin film photodetector structures synthesized by sol–gel technique. The prepared photodetector structures were studied for their response towards the illumination of UV radiations (λ = 365 nm and intensity = 24 μwatt/cm2). Incorporation of 20 nm thick gold (Au) on the ZnO film surface in continuous form of layer and nano-dots leads to an enhanced photoresponse (K = I on/I off) of 3.0×103 and 5.5×103 respectively as compared to 1.52×102 obtained for the pure ZnO film based structure. The existence of Au on ZnO surface which makes a schottky barrier at the Au–ZnO interface leads to the significant drop in dark current (I off) and is contributing for enhancing the photoresponse characteristics. In addition, well known plasmon propagating properties exhibited by Au nanoclusters are proved to be helpful in absorbing large amount of UV photons resulting in high photocurrent and hence enhanced response parameters. The physical and optical properties of the prepared photodetector structures are studied using XRD, UV-visible spectrophotometer and SEM respectively and have been correlated with the observed enhanced photoconducting response.
Ultraviolet (UV) photodetectors based on pure Zinc oxide (ZnO) thin film and metal doped ZnO (M:ZnO) thin film (M: Co, Mn, Ni, Pb, Ag and Au) have been prepared by sol–gel technique. The photoresponse characteristics have been studied for UV radiations of λ = 365 nm and intensity = 24 μwatt/cm2. The Au:ZnO thin film based photodetector exhibits a high photocoductive gain (K = 3.7×102) in comparison to other prepared photodetectors. Au doping in ZnO through substitution of Au+ ions at the Zn2+ sites in ZnO and also through occupation of Au at interstitial sites. A very low dark current is observed (0.06 μA) for the Au:ZnO photodetector which may be related to the formation of Au–ZnO schottky contacts inside the ZnO bulk. Besides, substituted Au+ at Zn2+ ions creates traps for free electrons which also decrease the dark current of the film. Upon UV illumination, these trapped electrons are released and contribute in photocurrent. Gold is known to be possessing plasmon propagating properties in a semiconducting medium. Increased absorption cross section of Au clusters in the presence of UV rays leads to increased absorption of UV rays and hence enhanced photoresponse characteristics.
The study addresses the coupled spatial scales in the physico-chemical variables and chaetognaths in the upwelling system of the eastern Arabian Sea during the 2005 summer monsoon. We studied the taxon between 0 and 1,000 m depth along seven zonal sections between 8° and 19°N and especially observed the vertical stratification of the animals. In the upwelling regions, higher chaetognath abundance was observed resulted by the local population growth and advection of the upwelling preferred epipelagic species. Abundance weight (Aw) value further helped to understand the mode of distribution of the chaetognath community around the upwelling locations. The variation in the depth-weighted average values of different species between the upwelling and non-upwelling sites helped to identify the dissimilarity in their coupling with the abiotic components. As this eastern boundary current region further draws research interest as one of the major natural oxygen deficient system in the global ocean, the role of this hypoxia was shelved separately from the influence of upwelling in the heterogeneity of distribution of chaetognaths. In our study, two mesopelagic species Eukrohnia fowleri and E. minuta were identified as the indicator species of this upwelling process. Our observation suggests that the temporal physical event (upwelling) plays a decisive role in the heterogeneity of the spatial abundance, community composition and diversity of chaetognaths in this least studied eastern boundary current system.
The Paper examines the adoption and use of linux operating system by Library and Information Science (LIS) Professionals in India.The study shows that there is a steady increase in LIS professionals’ curiosity and interest in adopting Linux based operating systems for Library automation, Content Management and Digital Library services. Library Professionals from South Indian states,with Kerala at the top,are found to be more familiar with Linux.The support from library authorities is also a pivotal factor for Indian libraries to switch over to linux flavours.
The theory of Special Relativity has been a centre of interest for the scientific community for more than a century now. In recent times, people have worked on various aspects of the subjects, besides attempting to disprove some of the postulates of Special Relativity and the emergence of ideas such as that of Doubly Special Relativity, one effort is especially noteworthy: Dr. Moshe Carmeli’s attempt at extending the concept of Special Relativity to the larger picture - our Cosmos. In his famous paper‘Cosmological Special Relativity: The Large-Scale Structure of Space, Time and Velocity’ published in 1997, Dr.Carmeli has laid the framework for Cosmological Special Relativity. This paper is an attempt at understanding the nuances of the subject and trying to work on certain key ideas put forth by the theory. I have focussed on the explanations provided by Cosmological Special Relativity for the accelerated expansion of the universe and the existence of Dark Matter, as per Galaxy Rotation Curves.
A potentially tridentate Schiff base has been prepared by condensing 2-amino-3-carboxyethyl-4,5-dimethylthiophene with 2-hydroxy-1-naphthaldehyde under well defined condition. The ligand is versatile in forming a series of metal complexes with transition metal ions such as manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II). The ligand and the metal complexes have been characterized on the basis of elemental analyses, molar conductance values, magnetic susceptibility data, NMR, UV-Visible, IR and EPR spectral studies wherever possible and applicable. The spectral studies reveal that the Schiff base behaves as monobasic tridentate, coordinating to the metal ion through azomethine nitrogen, ester carbonyl oxygen and the naphtholate oxygen after deprotonation. Analytical data reveal that nickel(II), copper(II) and zinc(II) complexes possess 1 : 1 metal-ligand ratios while manganese(II), iron(II) and cobalt(II) complexes exhibit 1 : 2 ratios. Molar conductance values support the non-electrolytic nature of the complexes. The electrochemical behaviour of the copper(II) complex has been investigated by cyclic voltammetry. The ligand and the metal complexes have been subjected to antibacterial studies and it has been observed that the complexes arc more potent bactericides than the ligands.
Electrical switching in bulk Ge20Te80-xInx(x = 0,6,10,14 & 16) glasses has been investigated. The glasses studied are found to exhibit current controlled negative-resistance behaviour and memory switching. Further, the switching voltage (Vt) is found to increase linearly with sample thickness in the range of 0.2mm to 0.45mm. It is observed that the variation of switching voltage (Vt) of Ge-Te-In glasses show a maximum value at an average coordination number = 2.52 (at x = 6, onset of rigidity percolation), there after decreases and a minimum is seen in the switching voltage at an average coordination number = 2.68 (at x = 14), which is likely to be the chemical threshold of the system. Beyond x = 14, switching voltage is found to increase again with composition.
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65 members
Karen Gabriel
  • Department of English
Geetanjali Sethi
  • Department of Physics
Priyanka Thakral
  • Department of Chemistry
Prashanto Chatterjee
  • Department of Mathematics
Chaitanya Varma
  • Department of Physics
Delhi, India