University of Delhi
  • Delhi, DELHI, India
Recent publications
Adventitious roots (AR) arise from nonroot parts of plants, in response to stress and wounding. Gas transport and mineral-nutrient uptake are the key functions of adventitious rooting. Phytohormones play a significant role in the formation of adventitious roots. While auxin and ethylene promote AR formation, cytokinin, gibberellin, jasmonic acid, and abscisic acid inhibit AR formation. Strigolactones are a special class of phytohormones, earlier classified as the repressors of AR development, are now known to modulate species-specific responses. The interaction of strigolactones (SL) with the other hormones regulates the development of AR. Besides regulating AR formation, SL is important for hyphal branching, seed germination, leaf shape and senescence, and secondary growth of plants. Furthermore, SLs act by imparting tolerance to biotic stress conditions, like root-knot nematode and leafy gall syndrome, and abiotic stress responses to drought, chilling, and salinity stress. Therefore, the present chapter is primarily focused on strigolactones-mediated adventitious roots formation.
In various woody and herbaceous plants, vegetative propagation is achieved mainly through stem cuttings. Under appropriate conditions, cuttings show potential to produce new adventitious root systems and subsequently regenerate into new plants. These roots develop as a wound response involving a series of anatomical events concomitant with several physiological, biochemical, and molecular changes. Adventitious roots may arise directly from preformed or newly induced primordia or through an intervening callus phase. The major anatomical rearrangements remain largely conserved across species. These comprise repeated cell divisions concurrent with differentiation and enlargement of the determined cells, now called root initials, and their gradual organization into the defined structure of a root primordium. The root primordium continuously grows and eventually emerges out of the epidermis. The various stages of AR formation are controlled by phytohormones, particularly auxin, signaling molecules, and coordinated gene regulation, bringing about changes necessary for the switch of cellular fate for AR initiation. The formation of ARs is a prerequisite for the establishment of the cutting into a plant and ensuring the success of propagation activity. Therefore, the present chapter attempts to comprehensively collate existing information on changes facilitating the development of adventitious roots in cuttings, with specific emphasis on the anatomical alterations accompanying the process.
Adventitious root organization is crucial process during the clonal proliferation of numerous plant types. Its role is indispensable in the preservation and propagation of rare and finest germplasm of forest and horticulture plant varieties. Induction of adventitious roots requires a systemic expression of multiple genes, which are regulated via a convoluted network of various internal and external (environmental) factors. Among all the limiting factors, the level of maturity has the most severe impact on the regenerative ability of trees, i.e., their regenerative ability decreases with increasing age. The rooting capacity is often relinquished during the process of juvenile (immature)-phase to mature-phase transition in forest plants. This decline in regeneration potential reduces the rooting ability and vigor of excised plants. Maturation-stimulated alteration (decline) of rooting potential is one of the prime reasons, which restricts the clonal proliferation of woody plant varieties. However, the exact mechanism that stimulates cells to induce or lose developmental (rooting) competence is still unknown. In this regard, this chapter describes the aspects of phase changes and their effects on clonal forestry.
Root-knot nematodes possess a major threat to agricultural production of various crops worldwide. The intensive use of chemical nematicides to control plant parasitic nematodes has adverse effects on our environment and human health. Owing to the importance of developing new strategies, an experiment was conducted to reveal the influence of arbuscular mycorrhizal fungus, Rhizoglomus fasciculatum and nematophagous fungus, Paecilomyces lilacinus alone or in combination with various organic amendments such as superphosphate, green and organic manure to control the infection of root-knot, nematode Meloidogyne incognita in a vegetable crop Capsicum annuum. These two fungi along with soil amendments significantly improved plant growth and fruit yield and effectively controlled infection of M. incognita. The dual inoculation of P. lilacinus and R. fasciculatum reduced the number of galls and egg masses, thereby revealing the controlled proliferation of M. incognita infection in C. annuum roots. The beneficial effect of these fungi further increased on supplementation of soil with organic or green manures. Inoculation of C. annuum with these two fungi showed a significant increase in egg parasitization; however, maximum effect was detected on dual inoculation. Amongst the soil amendments, the best response was obtained in case of green manure along with mycorrhizal fungus and P. lilacinus. Present study revealed that nematophagous and AM fungi, in combination with green manure were effective in controlling M. incognita, thus suggesting the use of such agents for biocontrol of plant parasitic nematodes in agriculture.
Background Cancer is considered one of the primary illnesses that cause morbidity and mortality in millions of people worldwide and due to its prevalence, there is undoubtedly an unmet need to discover novel anticancer drugs. As most of the target-specific anticancer drugs failed to achieve the expected result so far, new multi-targeted therapies using natural products have become significant. Natural products are readily applicable, inexpensive, accessible and acceptable therapeutic approaches with minimum cytotoxicity. This review explores the relationship between dietary factors and the probability of development of gastric cancer. Over the years, it has been proven that there are many natural products that have chemo-preventative effects such as vitamins, probiotics and prebiotics, green tea, and resveratrol on gastric cancer. Many investigations have looked into the links between dietary components and the risk of stomach cancer and a variety of protective and deleterious factors have been identified in our diet that is associated with gastric cancer. In this study, we have summarized the preventive and injurious components that affect the incidence of gastric cancer. Conclusion Based on the potential of natural products for the discovery of new compounds for the treatment of diseases, the purpose of the present review was to investigate the importance of dietary products mitigating the impacts due to the development of gastric cancer. The current analysis proves the protective as well as harmful roles of many elements which are found in our diet in the development of gastric cancer. Our findings can have significant public health implications in terms of gastric cancer prevention. There is an inherent need to offer an insight into benefits and risks, clinical trial designs future translational and cohort studies before effectively clinically translated.
Background and objectives India, the country with the largest market availability of antimicrobial fixed-dose combinations (FDCs), banned certain antimicrobial FDCs in September 2018. Our objective was to examine the impact of Government ban on the sales of antimicrobial FDCs. Methods The sales patterns of 14 of the 26 banned antimicrobial FDCs were analyzed using monthly private sector drug sales data from IQVIA (a comprehensive and nationally representative drug sales database) between January 2018 and December 2019. We carried out descriptive analyses to evaluate the trend in sales over time for banned and non-banned antimicrobial FDCs using cumulative sales volumes. Results Overall, the cumulative sales volume of banned antimicrobial FDCs declined by 75% between January and September 2018 and the same months of 2019, although some banned FDCs continued to be available in significant volumes. The effectiveness of the ban was offset by several pathways. First, the sales of combinations containing moieties belonging to the same drug-classes as the antimicrobials in the banned FDCs increased after the ban. Second, while certain formulations of particular combinations were banned, the sales of other non-banned formulation of these combinations increased. Third, in some cases, products containing new non-antimicrobial components added to the banned combinations remained available. Interpretation and conclusions While sales of the banned antimicrobial FDCs decreased in 2019, we identified several mechanisms that counterbalanced the ban, including implementation failure, rising sales of congeners, and products with additional non-antimicrobial components.
Silicon wet bulk micromachining is the most widely used technique for the fabrication of diverse microstructures such as cantilevers, cavities, etc. in laboratory as well as in industry for micro-electromechanical system (MEMS) application. Although, increasing the throughput remains inevitable, and can be done by increasing the etching rate. Furthermore, freestanding structure release time can be reduced by the improved undercutting rate at convex corners. In this work, we have investigated the etching characteristics of a non-conventional etchant in the form of hydroxylamine (NH 2 OH) added sodium hydroxide (NaOH) solution. This research is focused on Si{100} wafer as this orientation is largely used in the fabrication of planer devices (e.g., complementary metal-oxide semiconductors) and microelectromechanical systems (e.g., inertial sensors). We have performed a systematic and parametric analysis without and with 12% NH 2 OH in 10 M NaOH for improved etching characteristics such as etch rate, undercutting at convex corners, and etched surface morphology. 3D scanning laser microscope is used to measure average surface roughness ( R a ), etch depth (d), and undercutting length ( l ). Morphology of the etched Si{100} surface is examined using optical and scanning electron microscopes. The addition of NH 2 OH in NaOH solution remarkably exhibited a two-fold increment in the etching rate of a Si{100} surface. Furthermore, the addition of NH 2 OH significantly improves the etched surface morphology and undercutting at convex corners. Undercutting at convex corners is highly prudent for the quick release of microstructures from the substrate. In addition, we have studied the effect of etchant age on etching characteristics. Results presented in this article are of large significance for engineering applications in both academic and industrial laboratories.
In this present paper, we obtain hyperbolic, exponential, trigonometric function, other soliton solutions, and their combinations for the cold bosonic atoms in a zig-zag optical lattice model based on two efficient methods, such as the generalized Riccati equation mapping (GREM) method and generalized Kudryashov (GK) method. The used techniques are very reliable and effective tools and provide numerous exact soliton solutions of the nonlinear PDE. The zig-zag optical lattice model, widely used to represent the nonlinear wave and the soliton dynamics in fluid dynamics and plasma physics, is examined in this article to obtain exact optical soliton solutions and study their physical properties. For this, we first convert a partial differential equation (PDE) into an ordinary differential equation (ODE) by employing wave transformation and then split the equation into imaginary and real parts. The derived optical soliton solutions are illustrated graphically using Mathematica software to distinguish constant parameter values. Consequently, bell-shape, anti-bell-shape, traveling wave, periodic, mix periodic, singular soliton, and some new types of solitons demonstrate to validate these acquired outcomes with physical phenomena and make the results worthy. Furthermore, the 3D, 2D, and contour graphs are sketched to assign suitable constant parameters to illustrate the physical phenomena of the obtained solutions. The accomplished soliton solutions indicate that the applied computational system is a direct, reliable, productive, and more complex physical phenomenon. Symbolic computation is used in the software package Mathematica to obtain the various soliton solutions and different dynamical behavior of the newly formed solutions
Electrocaloric effect has been investigated in lanthanum doped lead zirconium titanate (PLZT) thick films for potential application in cooling devices. Modified sol gel technique has been used for the preparation of PLZT thick films. Dielectric constant has been enhanced from 497 to 1048 with minimum dielectric losses varying from 0.04 to 0.07 measured at 1 MHz with increase in La doping from 2% to 6%, respectively. The maximum and remnant polarizations have been observed to vary from 23 μC/cm² to 62 μC/cm² and from 18 μC/cm² to 49 μC/cm² with increase in the lanthanum doping level from 2% to 6%, respectively, measured at 20 Hz frequency. The recoverable energy storage density of 1.05 J/cm³ and an efficiency of 21% has been obtained for 2% lanthanum doping. The electrocaloric temperature change (ΔT) of 4.26K has been measured at 310K with an electrocaloric efficiency of 0.28 × 10⁻⁶ Km/V in the 6% La doped PZT film. These properties indicate that PZT thick films with 6% La doping have potential for application in cooling devices.
The objective of this study is to examine the influence of double dispersion on mixed convection flow over a vertical cone of an incompressible viscous fluid saturated porous medium. The mathematical model of the problem is designed in forms of governing equations and the non-dimensionalization is performed via appropriate transformations, to employ the numerical technique; the obtained non-similarity equations are solved numerically by the bivariate Chebyshev spectral collocation quasi-linearization method. The outcomes are reflected graphically and numerically for variation of the governing parameters Prandtl number, Schmidt number, buoyancy parameter, thermal and Solutal dispersion parameters on the velocity, temperature, and concentration profiles at the various stream-wise locations, respectively. Further, skin friction, heat, and mass transfer coefficients are also reflected. To authenticate the accuracy of the present computations, we have enclosed a comparison with a prior published results and it found in great consent. The residual analysis study is also pictured in the results and discussion section, which reflects the convergence and stability of the present computations.
This paper adopts and extends the theoretical lens of institutional imprinting to international business research. It analyses a secondary data set on Indian and Chinese foreign direct investment (FDI) flows to Africa, compiled for the period ranging from 2008 to 2018, to highlight the distinctiveness of Indian FDI. It argues that Indian FDI streams into better governed host countries with controlled corruption and high standards of accountability. This is in striking contrast with Chinese FDI, which is impervious to host country governance standards in its geopolitical quest for gaining economic supremacy in the region. India’s membership of the Commonwealth (CW) plays a vital role in the location and volume of its investments to Africa, whereas the Chinese Belt and Road Initiative (BRI) wields no influence on the location of its investment.
In this work, ZnO nanoparticles (NPs – L5 and L10) are biosynthesized using 5 mL and 10 mL leaf extract of Azadirachta indica, respectively. As-prepared L5/L10 NPs revealed hexagonal wurtzite structure while their surface is attached with phytochemicals coating. FESEM micrographs confirmed 50 – 120 and 30 – 70 nm rod-shaped L5/L10 ZnO nanoparticles. DLS study showed hydrodynamic sizes 580.41/356.2 nm and zeta potential values of −47.17/−51.70 mV for L5/L10, respectively indicating their good colloidal stability. The anticancer activity of L5/L10 NPs is evaluated via MTT assay which confirmed that the cell viability of A549 cells is significantly reduced depending on the dosage of L5/L10 NPs. Moreover, IC50 values are obtained as 125.64 and 115.63 μg/mL for L5 and L10, respectively. Furthermore, flow cytometry reveals 88 % and 89.3 % arrest of the G1 phase of the cell cycle due to the anticancer effect of L5 and L10 NPs, respectively.
Advances in conducting polymer-based nanocomposites (CPNCs) as sensing materials offer unique prospects to apprehend previously inaccessible sensing properties and applications. In this review article, the synthesis and properties of CPNCs are highlighted as pioneer transducers for designing advanced sensing devices. Synthetic strategies of CPNC are also discussed in the brief and classified into ex-situ and in-situ categories employing (1) chemical; (2) electrochemical; (3) photochemical; and (4) hybrid approach. The composite structure of conducting polymers (CPs), with inorganic and organic compounds, has enhanced surface adsorption, responsiveness, catalytic, and/or electron transport behavior for sensing applications. Thus, CPNCs are explored to sense atmospheric gases, humidity, explosives, water pollutants, and food adulterants. The literature reveals that sensor technology has been effectively improved in terms of sensitivity and selectivity due to progress in CPNCs. However, there are still several technical challenges that need to be solved for CPNCs based sensor technology. Herein, the key issues regarding the use of CPNC based materials in the development of state-of-the-art sensors are discussed. Furthermore, a perspective on the next-generation sensor technology concerning materials has been demonstrated with exclusive examples of conducting polymers based nano composite.
This paper is based on the study of structural, electronic, magnetic, elastic, phonon dynamics and thermodynamic properties of d0 half-Heusler alloys GeKZ (Z = Ca, Sr) using the Density Functional Theory (DFT) approach. The investigation is carried out using the spin-polarized calculations with pseudopotential approach using Generalized Gradient Approximation by Perdew–Burke–Ernzerhof (GGA-PBE). Both the compounds GeKCa and GeKSr are found to be structurally stable in the ferromagnetic α-phase. The electronic properties in the form of spin-polarized band-structures and density of states of the compounds GeKCa and GeKSr show that they are half-metallic in nature with a finite and large half-metallic band-gap of 0.37 eV and 0.29 eV respectively in the spin-up states and a metallic behavior in the spin-down states with 100 % spin-polarization at the Fermi-level. Integral magnetic moment of 1.00 μB is obtained for both the compounds which is in accordance with the Slater–Pauling Rule for half-Heusler alloys. The elastic properties show that the compounds are mechanically stable following Born stability criteria for cubic compounds and are found to be ductile in nature. The compounds have also been found to be dynamically stable against lattice vibrations on the basis of phonon dispersion calculations. They have also been explored regarding their thermodynamic properties using the quasi-harmonic approximation. They are also examined for the preservation of the integral magnetic moment against the lattice compression and expansion. The observed properties points towards the suitability of these compounds in the spintronics applications.
In this article, the problem of reliability inference of multicomponent stress–strength (MSS) from Kumaraswamy-G (Kw-G) family of distributions under progressive first failure censoring is considered. The reliability of MSS is considered when both the stress and strength variables follow Kw-G distributions with different first shape parameters and common second shape parameter. The maximum likelihood (ML) and Bayes estimators of reliability are derived when all the parameters are unknown. Also, the ML, uniformly minimum variance unbiased and Bayes estimators of reliability are derived in case of common shape parameter is known. The Bayesian credible and HPD credible intervals of reliability are developed using Gibbs sampling method. The performance of various estimates developed are discussed by a Monte Carlo simulation study. At last, two real life examples are considered for illustrative purposes.
A novel soy chhurpi product was developed by fermentation of soymilk using proteolytic Lactobacillus delbrueckii strains isolated from traditional chhurpi production of Sikkim Himalaya. Soymilk fermentation by L. delbrueckii WS4 was associated with the hydrolysis of globulin proteins, with observed antioxidant, and ACE-inhibitory activity which further increased upon simulated in vitro gastrointestinal digestion. Peptidomics analysis of soy chhurpi and its gastrointestinal digest resulted in the identification of bioactive peptides with ACE-inhibitory and antioxidant properties. In silico antihypertensive property prediction followed by molecular docking study demonstrated strong binding affinity of selected peptides with ACE. The glycinin-derived peptide, SVIKPPTDE escaped gastrointestinal digestion and demonstrated strong non-bond interactions with ACE catalytic residues. QSAR models predicted an ACE-inhibitory IC50 of 21.29 µM for SVIKPPTDE. This is the first report on the production of novel functional soy chhurpi cheese using defined starter strains and the identification of bioactive peptides in undigested and gastrointestinal digested soy chhurpi.
Self-powered photodetectors have attracted enormous attention for their high sensitivity, fast response with low power consumption. The unique set properties defined for various polymorphs of In2Se3 offers wide range of potential applications for optoelectronic and memory devices. Here, three phases of In2Se3 including, layered α-In2Se3 and β-In2Se3, and non-layered γ-In2Se3, are grown using pulsed laser deposition (PLD) technique. Deposition gas pressure is found to govern the formation of In2Se3 phases attributed to flux of Se atoms reaching the heated substrate. Band structure, density of states and work function for each phase is calculated using first principles calculations to understand their electronic properties. Based on the obtained work functions, it is found that Schottky junction based ultraviolet photodetectors using as grown In2Se3 films exhibit high performance with photo-responsivity of 1310 mA/W for α-In2Se3, 260 mA/W for β-In2Se3 and 240 mA/W for γ-In2Se3 in self-powered mode under an illumination of ultraviolet radiation. The obtained high self-powered photodetection is attributed to the non-centrosymmetric structure of α-In2Se3 and γ-In2Se3, which produce a built-in field due to in-plane spontaneous polarization. Thus, In2Se3 based self-powered photodetector prepared using PLD technique pave the way for low power optoelectronic device applications, environmental monitoring and military applications.
Nonstoichiometric titanium-oxide (TiOx) films are being extensively studied for MEMS bolometer applications. To have superior bolometer performance, the TiOx layers should have a high value of temperature coefficient of resistivity (TCR) and a low value of thermal conductivity. This paper presents the evolution of the electrical and thermal properties of RF sputtered TiOx films with the film thickness and stoichiometry. A series of amorphous TiOx films of 100 nm, 200 nm, and 400 nm thickness are deposited with different oxygen flow rates. X-ray photoelectron spectroscopy (XPS) study revealed the presence of only Ti⁴⁺ and Ti³⁺ oxidation states in the deposited films, and no TiO phase exists (no Ti²⁺ state). The oxygen-titanium atomic ratios (O/Ti) of the films are 1.5, 1.7, and 1.9. The TCR of the films is increased (from -1.1 %/K to -4.8%/K) with the increased oxygen content. The cross-plane thermal conductivities of the films are by the 3-ω technique. The thermal conductivity of the TiOx films is increased (0.5 W/m-K to 2.4 W/m-K) with the increase in film thickness and is independent of its ‘x’ values. Characteristics of MEMS bolometer pixel (17 mm pitch) are simulated based on the measured properties of the TiOx films. The film having 2.75 %/K TCR and 1.12 W/m-K thermal conductivity, exhibited minimum NETD (37.3 mK) with decent voltage responsivity (1.62x10⁶ V/W).
Present work reports the growth and optimisation of thin films of Gallium nitride (GaN) with preferred c-axis (0002) orientation on Si (111) substrate using the Laser Molecular Beam Epitaxy technique. For the development of optically efficient GaN thin film, the nitrogen gas flow during film deposition has been optimised and film properties are measured using the highly sensitive Surface Plasmon Resonance (SPR) technique in OTTO configuration. Structural, morphological and optical properties of the GaN thin films were studied using XRD, AFM, PL and FTIR spectroscopy. Varying the deposition gas flow from 1.3 sccm to 4 sccm led to a decrease in refractive index values from 2.77 to 2.21. By using the SPR technique, the refractive index (n) dispersion of GaN thin films was also analysed with the incident radiated wavelength.
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10,457 members
Anita Kamra Verma
  • Department of Zoology (Kirori Mal College)
Iqbal Singh
  • Department of Surgery(Urology Div)
Sumati Varma
  • Department of Commerce (Sri Aurobindo College Eve)
Rina Chakrabarti
  • Department of Zoology (Faculty of Science)
NORTH CAMPUS, 110007, Delhi, DELHI, India
Head of institution
P. C. Joshi