Browsing by Author "Singh, D"
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Item Bioacetoin Production by Bacillus subtilis subsp. subtilis Using Enzymatic Hydrolysate of Lignocellulosic Biomass(2023-07) Saini, M; Rapoport, A; Tiwari, S; Singh, DAbstract: Acetoin is an important bio-product useful in the chemical, food and pharmaceutical industries. Microbial fermentation is the major process for the production of bioacetoin, as the petroleum resources used in chemical methods are depleting day by day. Bioacetoin production using wild microorganisms is an easy, eco-friendly and economical method for the production of bioacetoin. In the present study, culture conditions and nutritional requirements were optimized for bioacetoin production by a wild and non-pathogenic strain of B. subtilis subsp. subtilis JJBS250. The bacterial culture produced maximum bioacetoin (259 mg L−1 ) using peptone (3%) and sucrose (2%) at 30 ◦C, 150 rpm and pH 7.0 after 24 h. Further supplementation of combinatorial nitrogen sources, i.e., peptone (1%) and urea (0.5%), resulted in enhanced titre of bioacetoin (1017 mg L−1 ) by the bacterial culture. An approximately 46.22–fold improvement in bioacetoin production was achieved after the optimization process. The analysis of samples using thin layer chromatography confirmed the presence of bioacetoin in the culture filtrate. The enzymatic hydrolysate was obtained by saccharification of pretreated rice straw and sugarcane bagasse using cellulase from Myceliophthora thermophila. Fermentation of the enzymatic hydrolysate (3%) of pretreated rice straw and sugarcane bagasse by the bacterial culture resulted in 210 and 473.17 mgL−1 bioacetoin, respectively. Enzy matic hydrolysates supplemented with peptone as a nitrogen source showed a two to four-fold improvement in the production of bioacetoin. Results have demonstrated the utility of wild type B. subtilis subsp. subtilis JJBS250 as a potential source for economical bioacetoin production by making use of renewable and cost-effective lignocellulosic substrate. Therefore, this study will help in the sustainable management of agricultural waste for the industrial production of bioacetoin, and in combating environmental pollution.Item Cool green-emissive Y2Si2O7:Tb3+ nanophosphor: auto-combustion synthesis and structural and photoluminescence characteristics with good thermal stability for lighting applications†(2024-05) Kumar, P; Singh, D; Kadyan, S; Kumar, H; Kumar, RA cheap, versatile, sustainable and energy-efficient gel-combustion method was applied to develop a series of green-emitting down-converted Y2Si2O7:Tb3+ (YPS:Tb3+) nanophosphors. Employing XRD-based Rietveld refinement approach, the phase purity and crystallographic evaluation of the produced phosphor were conducted, revealing a triclinic crystal with P 1 space group. EDX and TEM analyses were performed on the synthesized samples to determine their elemental composition and morphological properties. Diffuse reflectance spectra yielded 5.61 eV and 5.79 eV optical energy band gaps for the host and the optimized (0.04 mole of Tb3+) sample, respectively. UV light has the ability to excite the nanocrystalline phosphor in an efficient manner, leading to significant luminosity qualities attributed to the radiative relaxation of 5 D4 / 7 FJ (J = 6, 5, 4, 3). The bi-exponential decay function was derived by the PL decay curves. With an activation energy of 0.2206 eV, the Y1.96Si2O7:0.04Tb3+ phosphor exhibits good thermal quenching capabilities. Improved photometric attributes including CIE coordinates, CCT and color purity confirmed the green glow, indicating a strong competitor for cool-green emission in lighting applicationsItem Developments in conducting polymer-, metal oxide-, and carbon nanotube-based composite electrode materials for supercapacitors: a review(2024-03) Tundwal, A; Kumar, H; Binoj, B; Sharma, R; Kumar, G; Kumari, R; Dhayal, A; Yadav, A; Singh, D; Kumar, PSupercapacitors are the latest development in the field of energy storage devices (ESDs). A lot of research has been done in the last few decades to increase the performance of supercapacitors. The electrodes of supercapacitors are modified by composite materials based on conducting polymers, metal oxide nanoparticles, metal–organic frameworks, covalent organic frameworks, MXenes, chalcogenides, carbon nanotubes (CNTs), etc. In comparison to rechargeable batteries, supercapacitors have advantages such as quick charging and high power density. This review is focused on the progress in the development of electrode materials for supercapacitors using composite materials based on conducting polymers, graphene, metal oxide nanoparticles/nanofibres, and CNTs. Moreover, we investigated different types of ESDs as well as their electrochemical energy storage mechanisms and kinetic aspects. We have also discussed the classification of different types of SCs; advantages and drawbacks of SCs and other ESDs; and the use of nanofibres, carbon, CNTs, graphene, metal oxide– nanofibres, and conducting polymers as electrode materials for SCs. Furthermore, modifications in the development of different types of SCs such as pseudo-capacitors, hybrid capacitors, and electrical double-layer capacitors are discussed in detail; both electrolyte-based and electrolyte-free supercapacitors are taken into consideration. This review will help in designing and fabricating high-performance supercapacitors with high energy density and power output, which will act as an alternative to Li-ion batteries in the future.Item A green light emissive LaSr2AlO5:Er3+ nanocrystalline material for solid state lighting: crystal phase refinement and down-conversion photoluminescence with high thermal stability(2024-09) Kumar, P; Singh, D; Kumar, HThe present study reveals the structural and optoelectronic characteristics of a down-converted (DC) green luminous Er3+ doped LaSr2AlO5 phosphor that was produced by employing an efficient and reliable gel combustion process assisted with urea as a fuel. Using Rietveld refinement of diffraction data, the crystal structure and phase formation were examined. The surface morphology and elemental configuration of the phosphor were analyzed via TEM and EDX spectroscopy, respectively. The band gap of LaSr2AlO5 (5.97 eV) and optimized La0.96Sr2AlO5:4 mol% Er3+ (5.51 eV) classify the optimized sample as a direct band-gap material. The PL peaks located in the visible range corresponding to transitions 2 H9/2 / 4 I15/2 (406 nm), 2 H11/2 / 4 I15/2 (520 nm), 4 S3/2 / 4 I15/2 (550 nm), and 4 F9/ 2 / 4 I15/2 (665 nm) were revealed by photoluminescence spectroscopy under 377 nm excitation. Above 4 mol% Er3+ doping, concentration quenching was observed, which was controlled by the quadrupole–quadrupole interaction. Based on the findings of the double exponential fitting of lifetime curves acquired from the emission spectra at lex = 377 nm and lem = 550 nm, the average lifetime of the excited levels of considered nanomaterials was estimated. The temperature-dependent emission spectra of the La0.96Sr2AlO5:4 mol% Er3+ sample were collected in the range 298–498 K. The considered phosphor was found to have a high thermal stability as evidenced by the luminous intensity being sustained at 74.29% at 498 K compared to the intensity at ambient temperature (298 K) with an activation energy of 0.1453 eV. The calculated color purity and superb chromaticity coordinates indicates that the phosphors have a high degree of color purity, which further supports its applicability as a green component in solid-state lighting.Item Green mycosynthesis of silver nanoparticles exhibiting antimalarial activity(2024-07) Shankar, A; Kaushik, N; Kumar, V; Malik, V; Singh, DIn the present study, different parameters, affecting the growth of Thermomyces lanuginosus BJMDU1 and extracellular synthesis of silver nanoparticles (AgNPs), were studied. Culture extract of thermophilic mould Thermomyces lanuginosus BJMDU1 showed potential in green synthesis of silver nanoparticles when the fungus was grown in a sucrose yeast extract medium (pH 8.0) at 45°C. Mycosynthesis of AgNPs was enhanced in the presence of light using 2 mM AgNO3 and 200 µl of culture extract at 50°C. The reaction parameters significantly improved the synthesis of AgNPs. Techniques like UV-Vis & FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy and dynamic light scattering were used to characterise AgNPs. Biogenic nanoparti cles showed an absorption peak at 430 nm having 80 nm size. Biogenic AgNPs showed potent antibacterial and antiplasmodial activity with no haemolysis up to 40 µg/ml. The p-nitrophenol was catalytically reduced to p-aminophenol by AgNPs. Therefore, green mycosynthesised AgNPs could be used in the therapeutics and remediation of environmental pollutants.Item Molecular changes associated with migratory departure from wintering areas in obligate songbird migrants(2021-04) Sharma, A; Singh, D; Gupta, P; Bhardwaj, S; Kaur, I; Kumar, VDay length regulates the development of spring migratory and subsequent reproductive phenotypes in avian migrants. This study used molecular approaches, and compared mRNA and proteome wide expression in captive redheaded buntings that were photostimulated under long-day (LD) conditions for 4 days (early stimulated, LD-eS) or for ∼3 weeks until each bird had shown 4 successive nights of Zugunruhe (stimulated, LD-S); controls were maintained under short days. After ∼3 weeks of LD, photostimulated indices of the migratory preparedness (fattening, weight gain and Zugunruhe) were paralleled with upregulated expression of acc, dgat2 and apoa1 genes in the liver, and of cd36, fabp3 and cpt1 genes in the flight muscle, suggesting enhanced fatty acid (FA) synthesis and transport in the LD-S state. Concurrently, elevated expression of genes involved in the calcium ion signalling and transport (camk1 and atp2a2; camk2a in LD-eS), cellular stress (hspa8 and sod1, not nos2) and metabolic pathways (apoa1 and sirt1), but not of genes associated with migratory behaviour (adcyap1 and vps13a), were found in the mediobasal hypothalamus (MBH). Further, MBH-specific quantitative proteomics revealed that out of 503 annotated proteins, 28 were differentially expressed (LD-eS versus LD-S: 21 up-regulated and 7 down-regulated) and they enriched five physiological pathways that are associated with FA transport and metabolism. Thesefirst comprehensiveresults ongene and protein expression suggest that changes in molecular correlates of FA transport and metabolism may aid the decision for migratory departure from wintering areas in obligate songbird migrants.Item Novel archetype in cancer therapeutics: exploring prospective of phytonanocarriers(2022-10) Yadav, N; Singh, D; Rawat, M; Sangwan, NThis paper reports various types of cancer, their incidence, and prevalence all over the globe. Along with the discovery of novel natural drugs for cancer treatment, these present a promising option which are eco-friendly, safe, and provide bet ter acceptability in comparison to synthetic agents that carries multiple side effects. This paper provides an idea about various nanocarriers and phytochemicals, along with how their solubility and bioavailability can be enhanced in nanocar rier system. This report combines the data from various literature available on public domain including PubMed on research articles, reviews, and along with report from various national and international sites. Specialized metabolites (polyphenols, alkaloids, and steroids etc) from medicinal plants are promising alternatives to existing drugs. Studies have suggested that the treatment of cancer using plant products could be an alternative and a safe option. Studies have shown with the several cell lines as well as animal models, that phytomolecules are important in preventing/treating cancer. Phytochemicals often outperform chemical treatments by modulating a diverse array of cellular signaling pathways, promoting cell cycle arrest, apoptosis activation, and metastatic suppression, among others. However, limited water solubility, bioavailability, and cell penetration limit their potential clinical manifestations. The development of plant extract loaded nanostructures, rendering improved specificity and efficacy at lower concentrations could prove effective. Nanocarriers, such as liposomes, nanostruc tured lipids, polymers, and metal nanoparticles, have been tested for the delivery of plant products with enhanced effects. Recent advances have achieved improvement in the the stability, solubility, bioavailability, circulation time, and target specificity by nanostructure-mediated delivery of phytochemicals. Nanoparticles have been considered and attempted as a novel, targeted, and safe option. Newer approaches such as phyto-nanocarriers with carbohydrates, lignin, and polymers have been considered even more selective and effective modes of drug delivery in biomedical or diagnostic applications.Item Realization of a green-emitting pyrosilicate structured Er3+-activated Y2Si2O7 phosphor: a systematic study of opto-electronic characteristics and thermal stability for lighting applications(2024-05) Kumar, P; Singh, D; Singh, S; Kumar, H; Kumar, RA series of green-emitting Y2−xSi2O7:xEr3+ phosphors (x = 1–7 mol%) have been successfully synthesized using a straightforward gel-combustion method facilitated by urea. X-ray diffraction analysis provided specific patterns for samples, confirming a consistent triclinic phase across erbium-doped structures compared to undoped structures. Studies using TEM and EDX were conducted to identify the surface related characteristics and chemical composition of the synthesized nanophosphor, respectively. The band gap was determined to be 5.55 eV and 5.80 eV for the host material and optimal sample, respectively. The primary peak of excitation, observed at 379 nm, represents the highly sensitive electric dipole transition from the 4 I15/2 state to the 4 G11/2 level, suggesting that the prepared phosphors could effectively absorb NUV light for activation. The PL profiles of Y2−xSi2O7:xEr3+ (x = 1–7 mol%) phosphors demonstrate characteristic emissions at 409 nm (2 H9/2 / 4 I15/2), 522 nm (2 H11/2 / 4 I15/2), 553 nm (4 S3/2 / 4 I15/2) and 662 nm (4 F9/2 / 4 I15/2). In accordance with Dexter's theory, luminescence quenching observed at a concentration of 4 mol% Er3+ is attributed to dipole-quadrupole interactions. The optimal sample demonstrates excellent thermal stability, indicated by its luminescence at different temperatures and activation energy of 0.2641 eV. Additionally, the CIE, color purity and CCT values of the fabricated nanomaterials make it ideal for use in lighting applications.Item Remediation of toluidine blue O dye from aqueous solution using surface functionalized magnetite nanoparticles(2024) Jangra, A; Kumar, R; Singh, D; Kumar, H; Kumar, J; Kumar, P; Kumar, SIn the current study, tannic acid-functionalized iron oxide nanoparticles have been synthesized using a cost-effective co-pre cipitation method and subsequently characterized using various instrumentation techniques such as Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, and thermal gravimetric analysis. Further, these surface-modified magnetite nanoparticles have been used for the adsorption of toluidine dye from an aqueous solution. The adsorption process was accompanied using batch procedure, and influences of several factors such as adsorbent dose, contact time, pH, temperature, and initial concentration of adsorbate were inspected concurrently. The maximum adsorp tion capacity of tannic acid-functionalized magnetite nanoparticles was found to be 50.68 mg/g. The adsorption process was observed to follow the Temkin isotherm model, whereas the kinetic study was well described by pseudo-second order. The thermodynamic study revealed the adsorption process to be endothermic and spontaneous in nature with a high degree of freedom between adsorbent and adsorbate. Therefore, the study indicated that the tannic acid-functionalized magnetite nano particles have promising adsorption capability and can be used as an excellent adsorbent for the removal of toluidine blue O dye from the aqueous solution.Item Sporotrichum thermophile culture extract-mediated greener synthesis of silver nanoparticles: Eco-friendly functional group transformation and anti-bacterial study(2020-10) Shankar, A; Kumar, V; Kaushik, N; Kumar, A; Malik, V; Singh, D; Singh, BThermophilic mould Sporotrichum thermophile BJTLRMDU7 played the role in greener synthesis of the silver nanoparticles (AgNPs) extracellularly using silver nitrate. The change in colour from transparent to dark brown primarily indicated the formation of AgNPs due to reduction of Ag (I) ions to Ag by the fungal culture extract. Nanoparticles synthetic process was optimized using “one variable at a time” approach. Sucrose containing medium having pH 8.0 supported the synthesis of AgNPs by the mould at 45 C. Furthermore, presence of light significantly accelerated the formation of silver nanoparticles. AgNPs were characterized by various techniques like UV–vis & FT-IR spectroscopy, dynamic light scattering (DLS) and X-ray diffraction (XRD). Appearance of a band at 426 nm in UV–vis spectrum revealed the reduction of Ag(I) ions to Ag (0) by mould’s culture filtrate. DLS data showed that AgNPs bear an average size of 70 nm, while XRD data revealed particle size of 40 nm. The application of AgNPs with their functional group transformation has successfully reduced p-nitrophenol into p aminophenol in an eco-friendly manner in the presence of light and NaBH4. Further, the synthesized AgNPs showed anti-bacterial potential against Gram positive and Gram negative bacteria.