Showing papers by "University of Madras published in 2022"

Selective room temperature ammonia gas sensor using nanostructured ZnO/CuO@graphene on paper substrate

Abstract: In this work, we have grown ZnO/CuO nanoflowers on graphene printed paper substrates by the hydrothermal method. The hypothesis of the present work is the role of ZnO and CuO composited graphene structures as affordable substrates for room temperature ammonia gas sensor. To fabricate the conductive substrate, the biomass derived graphene has been formulated as conductive ink and printed (20 µm) on the paper substrate. The optical, structural, and morphological studies confirm the formation of hierarchical nanoflower like ZnO/CuO@graphene substrate. The chemiresistive gas sensor studies evident that, the ZnO/CuO@graphene substrates have higher sensing performance in the presence of ammonia (4.9%) for the concentration as low as 5 ppm at room temperature. It also shows a quick response and recovery time of 4.1 s and 2 s, respectively. Our present method will be an effective methodology for the fabrication of cost-effective and rapid detection of ammonia gas in the ambient environment and can be also further suitable for non-invasive earlier diagnosis of diseases from exhaled breath.

Novel pure α-, β-, and mixed-phase α/β-Bi2O3 photocatalysts for enhanced organic dye degradation under both visible light and solar irradiation

Abstract: Combining the pure α- and β-phases of bismuth oxide enhances its photocatalytic activity under both visible and solar irradiation. α-Bi2O3, β-Bi2O3, and α/β-Bi2O3 were synthesized by a solvothermal calcination method. The structural, optical, and morphological properties of the as-synthesized catalysts were analyzed using XRD, UV-DRS, XPS, SEM, TEM, and PL. The bandgaps of α/β-Bi2O3, α-Bi2O3, and β-Bi2O3 were calculated to be 2.59, 2.73, and 2.34 eV, respectively. The photocatalytic activities of the catalysts under visible and solar irradiation were examined by the degradation of carcinogenic reactive blue 198 and reactive black 5 dyes. The kinetic plots of the degradation reactions followed pseudo-first-order kinetics. α/β-Bi2O3 exhibited higher photocatalytic activity (∼99%) than α-Bi2O3 and β-Bi2O3 under visible and solar irradiation. The TOC and COD results confirmed the maximum degradation ability of α/β-Bi2O3, and the decolorization percentage remained above 90%, even after five cycles under visible irradiation. The photocatalytic dye degradation mechanism employed by α/β-Bi2O3 was proposed based on active species trapping experiments.

Impact of Hygrophila auriculata supplementary diets on the growth, survival, biochemical and haematological parameters in fingerlings of freshwater fish Cirrhinus mrigala (Hamilton, 1822).

Abstract: The present study investigates the effects of Supplementary diet Hygrophila auriculata on the growth, survival, biochemical and haematological parameters of Cirrhinus mrigala. The seaweed was administered to the fish possessing an initial average weight of 14.063 ± 1.828 g. Fish were fed with supplementary diet H. auriculata exhibited significant difference (P < 0.05) in the growth performance, haematological indices such as RBC count, haematocrit volume, haemoglobin, WBC, MCV, MCH and MCHC concentration in contrast to the control after a period of 8 weeks. Also, there were significant differences in biochemical parameters (P < 0.05), between the fish supplemented with dietary H. auriculata extract and the control group. These findings suggest that the administration of H. auriculata extract has a positive effect on the immunological indices and the immune system activity in Mrigal fish.

Role of bioglass in enamel remineralization: Existing strategies and future prospects-A narrative review.

Abstract: Enamel, once formed, loses the ability to regenerate due to the loss of the formative ameloblasts. It is subjected to constant damaging events due to exposure to external agents and oral microbiomes. An enamel remineralization process targets to replenish the lost ionic component of the enamel through a multitude of methods. Enamel remineralization is highly challenging as it has a complex organized hierarchical microstructure. Hydroxyapatite nanocrystals of the enamel vary in size and orientation along alignment planes inside the enamel rod. The inability of the enamel to remodel unlike other mineralized tissues is another substantial deterrent. One of the well-known biomaterials, bioglass (BG) induces apatite formation on the external surface of the enamel in the presence of saliva or other physiological fluids. Calcium, sodium, phosphate, and silicate ions in BG become responsive in the presence of body fluids, leading to the precipitation of calcium phosphate. Studies have also demonstrated the bactericidal potential of BG against Streptococcus mutans biofilms. The anticariogenicity and antibacterial activity were found to be enhanced when BG was doped with inorganic ions such as F, Ag, Mg, Sr, and Zn. Due to the versatility of BG, it has been combined with a variety of agents such as chitosan, triclosan, and amelogenin to biomimic remineralization process. Key strategies that can aid in the development of contemporary enamel remineralization agents are also included in this review.

Hardware-Based Document Image Thresholding Techniques Using DSP Builder and Simulink

Abstract: This paper presents the basic thresholding techniques using Simulink and DSP builder tool for removing the show-through noise from Document images using Altera Cyclone® V FPGA kit. Initially, show-through noise from the document images was removed using the thresholding method in the OpenCV environment and compared the results with the FPGA results. Then, we created a library file for Cyclone® V 5CSEMA5F31C6N series, as board block in DSP builder. We have designed, developed and implemented four methods of thresholding techniques using Simulink and DSP builder. The OpenCV software and Altera DE1-SoC board hardware results were compared qualitatively and quantitatively. DSP builder and Simulink make complex tasks like image processing and reduce the complications in designing the structure of algorithm, which pave the way for hardware co-simulation.

Anticancer effect of marine bivalves derived polysaccharides against human cancer cells

Abstract: In recent decades, studies on cancer prophylactics and therapeutics with development of novel anticancer drugs have garnered interest on a global scale. The diverse marine environment is a major source of biocompounds and has been acknowledged as an important platform for drug discovery. A wide variety of novel agents in the form of protein, polysaccharide, polypeptide and steroid from marine microbes, plants and animals are under preclinical and clinical evaluation as potential anticancer drugs. Polysaccharides, with their manifold structures and side groups, have been extensively investigated in biomedical and pharmaceutical fields. The present study investigates the potential of polysaccharides extracted by enzyme hydrolysis from five marine bivalves to inhibit human cancer cells. Cytotoxicity of crude polysaccharides was analyzed using a normal cell line (vero). Antiproliferative effect of polysaccharides on the breast (MDA-MB-231), cervical (HeLa), liver (HepG2) and colon (HT-29) cancer was evaluated by 3-(4, 5 dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide assay (MTT). The polysaccharides from different bivalve species showed varied results on different cell lines but highest inhibitory activity was observed in the polysaccharide of Donax variabilis with IC50 at the concentration 350 μg/mL in MDA-MB-231 and HeLa cells, 400 μg/mL in HepG2 cells and 200 μg/mL in HT-29 cells. Apoptosis-related characteristics were observed by cell morphological observation and nuclear morphological analysis by propidium iodide staining. The late stages of apoptosis were detected by dual acridine orange/ethidium bromide staining and confirmed by DNA fragmentation assay and MMP using Rhodamine 123 stainings. The results obtained substantiate that novel polysaccharides from marine bivalves are potent antiproliferative agents and further studies might unveil a promising anticancer drug.

Upconversion, MRI imaging and optical trapping studies of silver nanoparticle decorated multifunctional NaGdF4:Yb,Er nanocomposite.

Abstract: The multifunctional upconversion nanoparticles (UCNPs) are fascinating tool for biological applications. In the present work, photon upconverting NaGdF4:Yb,Er and Ag nanoparticles decorated NaGdF4:Yb,Er (NaGdF4:Yb,Er@Ag) nanoparticles were prepared using a simple polyol process. Rietveld refinement was performed for detailed crystal structural and phase fraction analysis. The morphology of the NaGdF4:Yb,Er@Ag was examined using high-resolution transmission electron microscope, which reveals silver nanoparticles of 8 nm in size were decorated over spherical shaped NaGdF4:Yb,Er nanoparticles with a mean particle size of 90 nm. The chemical compositions were confirmed by EDAX and inductively coupled plasma-optical emission spectrometry analyses. The upconversion luminescence (UCL) of NaGdF4:Yb,Er at 980 nm excitation showed an intense red emission. After incorporating the silver nanoparticles, the UCL intensity decreased due to weak scattering and surface plasmon resonance effect. The VSM magnetic measurement indicates both the UCNPs possess paramagnetic behaviour. The NaGdF4:Yb,Er@Ag showed computed tomography imaging. Magnetic resonance imaging study exhibited better T1 weighted relaxivity in the NaGdF4:Yb,Er than the commercial Gd-DOTA. For the first time, the optical trapping was successfully demonstrated for the upconversion NaGdF4:Yb,Er nanoparticle at near-infrared 980 nm light using an optical tweezer setup. The optically trapped UCNP possessing paramagnetic property exhibited a good optical trapping stiffness. The UCL of trapped single UCNP is recorded to explore the effect of the silver nanoparticles. The multifunctional properties for the NaGdF4:Yb,Er@Ag nanoparticle are demonstrated.

Biosynthesised Silver Nanoparticles Loading onto Biphasic Calcium Phosphate for Antibacterial and Bone Tissue Engineering Applications

Abstract: Biphasic calcium phosphate (BCP) serves as one of the substitutes for bone as it consists of an intimate mixture of beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) in different ratios. BCP, because of its inbuilt properties such as osteoconductivity, biocompatibility, and biostability in several clinical models serves as a bone substituent for orthopedic applications. Therefore, the present study aimed to assess the effectiveness of silver (Ag) nanoparticles (NPs) combined with BCP composites for the orthopedic sector of bone tissue regeneration and growth. In this regard, we first synthesized Ag-BCP microclusters by the double-emulsion method and then characterized the composite for various physicochemical properties, including the crystallinity and crystal structure, bonding and functionality, porosity, morphology, surface charges, topography, and thermal stability. In addition, the antibacterial activity of Ag-BCP was tested against gram-positive and gram-negative microorganisms such as Staphylococcus aureus, Candida albicans, and Escherichia coli. Finally, the cytocompatibility of Ag-BCP was confirmed against the fibroblast cells in vitro.

Anthocyanin: A Natural Dye Extracted from Hibiscus Sabdariffa (L.) for Textile and Dye Industries

Abstract: Environmental pollution is one of the major issues facing all countries throughout the world. Environmental degradation is occurring and creating crises in day-to-day life due to the increasing amount of chemicals used in industries, where even the effluents processed out after treatment also contain some trace elements. Hence the extraction of enzymes using natural methods is an alternative for the production of dye in order to reduce pollution, which in turn helps to nourish and protect the environment for future generations. Hibiscus sabdariffa (L.) is a rich source of anthocyanins that is further enhanced by callus formation and accumulated by increasing the sucrose concentration. Anthocyanin pigments were extracted using acidified ethanol. The dye obtained was screened by GC-MS analysis and its dyeing process used in the textile industry. The study showed certain properties affected the coloring nature depending on the cloth used. The color of anthocyanin pigment depends on the pH maintained and also shows adaptability to varied environmental conditions.

Deep Convolutional Networks in Gender Classification Using Dental X-Ray Images

Abstract: The process of gender classification is mostly done in dental biometrics. Dental biometrics is useful when there is an occurrence of massive calamity. In this study, a new method is proposed for the human classification of male and female using panoramic X-ray images. The proposed model is built using sequential deep convolutional neural networks, to execute binary classification. The training of the model was done using panoramic X-ray images and the model was able to attain an accuracy of 95%.

Antiproliferative potentials of chitin and chitosan encapsulated gold nanoparticles derived from unhatched Artemia cysts

Abstract: The recent increase in the usage of metallic nanoparticles (NPs) individually or the one coated with polymeric shells in the biomedical sector are helpful to control the unwanted toxicities, non-targeted localizations, enhance the probe-cellular interactions etc. Herein, we report the synthesis, characterization, and testing of photon-induced gold (Au) NPs encapsulated chitin and chitosan, which are derived from unhatched Artemia cysts. In this, the chitin and chitosan biopolymers are formed by a biosynthetic route and then subjected to a reaction in the presence of HAuCl4 for the encapsulation of AuNPs. Thus formed NPs are thoroughly studied for the surface morphology, functionality, and crystallinity using SEM/TEM, DLS, and FTIR respectively. Further, the antiproliferative capacity of as-synthesized chitin and chitosan stabilized AuNPs are being tested using two different cell types of human colon cancer (HT-29) and lung cancer (A549). The human tumor cell lines confirm the specific cytotoxicity. The optimized concentration of chitin and chitosan-loaded AuNPs showed a maximum anticancer activity in human lung cancer cells (A549) as compared with colon cancer (HT-29). Also, the chitosan-AuNPs have a potential cytotoxic effect against the human lung cancer cell line (A549) than that of the corresponding chitin-AuNPs. Finally, the study utilizes chitin and chitosan biopolymers generated from uncharted Artemia cysts for the formation of useful anticancer agents that has specific applications in the biomedical sector as bioimaging and drug delivering candidates.

Effects of material properties of band‐gap‐graded Cu(In,Ga)Se ₂ thin films on the onset of the quantum efficiency spectra of corresponding solar cells

Abstract: Polycrystalline Cu(In,Ga)Se2 (CIGSe) thin-film solar cells exhibit gradual onset in their external quantum efficiency (EQE) spectra whose shape can be affected by various CIGSe material properties. Apart from influences on the charge-carrier collection, a broadening of the EQE onset leads to enhanced radiative losses in open-circuit voltage (Voc). In the present work, Gaussian broadening of parameters describing the EQE onset of thin-film solar cells, represented by the standard deviation, 𝜎total, was evaluated to study the impacts of the effective band-gap energy, the electron diffusion length, and the Ga/In gradient in the CIGSe absorber. It is shown that 𝜎total can be disentangled into contributions of these material properties, in addition to a residual component 𝜎residual. Effectively, 𝜎total depends only on a contribution related to the Ga/In gradient as well as on 𝜎residual. The present work highlights the connection of this compositional gradient, the microstructure in the polycrystalline CIGSe absorber, and the luminescence emission with the residual component 𝜎residual. It is demonstrated that a flat band-gap with no compositional gradient in the bulk of the CIGSe absorber is essential to obtain the lowest 𝜎total values and thus result in lower recombination losses and gains in Voc.

Carbon dot–V2O5 layered nanoporous architectures for electrochemical detection of Bisphenol A: An analytical approach

Abstract: A novel carbon dot–Vanadium pentoxide (C–dot–V2O5) nanoporous material was synthesised by thermal decomposition method. C–dot was prepared from cow milk by hydrothermal treatment followed by thermal treatment with ammonium metavanadate (NH4VO3) to achieve C–dot–V2O5 nanoporous structure. The C–dot incorporation into the V2O5 lattice was confirmed by various spectroscopic and microscopic characterization. Cyclic voltammetry (CV) and electrochemical impedance studies (EIS) were carried out to study the electrochemical behaviour a of as fabricated C–dot–V2O5 nanoporous modified glassy carbon electrode (C–dot–V2O5/GCE). The electrochemical analysis confirmed that C–dot–V2O5/GCE exhibited high electrochemical surface area, uniform pore size and electron transfer rate constant. Further, the fabricated C–dot–V2O5/GCE utilized Bisphenol A (BPA) detection in the concentration range of 5 × 10–9 M to 9.2 × 10–3 M using ampe riometric technique. The electrochemical results clears the C–dot–V2O5/GCE electrode was able to detection the BPA at 8.0 × 10–10 M level with the maximum sensitivity of 0.0681 µAµM–1. Finally the developed C–dot–V2O5/GCE for BPA sensor was evaluated in drinking water and milk samples which confirms analytical applicability of the sensor.