53 results on '"Kumar, Mahesh"'
Search Results
2. Induction heating of sugarcane juice: thermo-enviro-economic analyses.
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Grewal, Rahul and Kumar, Mahesh
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INDUCTION heating , *SUGARCANE , *ENERGY dissipation , *HEAT flux , *INDUSTRIAL costs , *VALUE (Economics) - Abstract
Heating of sugarcane juice gives concentrated sugarcane juice (CSJ) which becomes raw material for the production of a variety of value added products. Conventional ways of CSJ production are environment polluting and indulge in huge amount of energy losses. In this study, an attempt is made to obtain final CSJ (98°B) by induction heating (IH) which is environment friendly and causes minimum energy losses. The experiments are performed at constant heat flux (9947.5 W m−2) on samples of sugarcane juice having 14.2°B, 18.8°B, 23.9°B, and 27.4°B values of initial brix contents. Thermo-enviro-economic analyses are carried out for the experiments conducted on given samples. The results concluded that time required for obtaining final CSJ decreases and evaporation rate increases with increase in initial brix value of sugarcane juice. The energy required for obtaining final CSJ from sugarcane juice of 27.4°B is 683.43 kJ which is 154.3% less as compared to that of fresh sugarcane juice heating with 14.2°B. The environmental parameters have no discernible effects of initial brix value while economic factors were improved. IH is observed thermally and environmentally beneficial with lower costs of CSJ production from the juice of higher initial brix contents. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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3. Experimental forced convection greenhouse and indirect cabinet drying of date fruits: a comparative study.
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Kumar, Mahesh, Shimpy, Sahdev, Ravinder Kumar, Sansaniwal, Sunil Kumar, Bhutani, Vijay, and Manchanda, Himanshu
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DATES (Fruit) , *FORCED convection , *FRUIT drying , *HEAT convection , *HEAT transfer coefficient , *GREENHOUSE plants - Abstract
This article is a comparison of the date fruits drying performance of two most simple and common type of solar dryers. A simple even span type forced convection greenhouse dryer (FCGHD) and a forced convection cabinet solar dryer (FCCSD) were developed and tested under the climate of Hisar, India. The average values of convective heat transfer coefficients (HTC) were calculated as 0.46 and 0.53 W m−2 °C−1 for FCGHD and FCCSD, respectively. The respective average evaporative HTC was evaluated as 64.58 and 276.06 W m−2 °C−1. The drying efficiency and specific energy consumption for date fruits drying under FCCSD were, respectively, 55.2% higher and 37.87% lower than that of FCGHD. Amongst seven considered thin layer drying models, Midilli–Kucuk model showed the highest commensuration to the experimentally evaluated drying data of moisture ratio for date fruits. Higher values of effective moisture diffusivity and lower values of activation energy were observed under FCCSD. The economic prospective of both the drying arrangements has also been presented. [ABSTRACT FROM AUTHOR]
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- 2023
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4. Relativistic modeling of stellar objects in a Schwarzschild's coordinates with embedded class one spacetime.
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Prasad, Amit Kumar, Kumar, Mahesh, and Kumar, Jitendra
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EINSTEIN field equations , *COMPACT objects (Astronomy) , *SPACETIME , *SPEED of sound , *ANALYTICAL solutions , *GEOMETRIC modeling - Abstract
In this study, we investigate a new relativistic anisotropic Einstein field equations solution for compact stars under embedding class 1 conditions. In order to do this, we apply the Karmarkar condition and the embedding class one technique. By taking Buchdahl type metric potential g rr into consideration, the precise analytical solution has been investigated. We have studied physical characteristics of various compact star using this analytical solution. Central singularities are absent from the solution. We have explored thermodynamic observables inside the stellar models, such as radial and tangential pressures, matter density, anisotropic factor, energy conditions, TOV, red-shift, and the speed of sound, etc., after establishing this space-time geometry for the stellar models. From the graphical representation of various physical characteristics, it is demonstrated that our model meets all the specification for ultra-high density compact bodies. [ABSTRACT FROM AUTHOR]
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- 2023
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5. Effect of seasons and photoperiods on seminal attributes and sperm morphology in Holstein Friesian × Sahiwal crossbred dairy bulls.
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Mandal, Dilip Kumar, Kumar, Mahesh, and Tyagi, Shrikant
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SEMEN , *SPERMATOZOA , *AUTUMNAL equinox , *SEMEN analysis , *BULLS , *VERNAL equinox - Abstract
Cattle being non-seasonal breeding species, effects of photoperiods on sperm traits and morphology had been reported inadequately in breeding bulls. To elucidate the plausible existence of effects of photoperiods and seasons, seminal traits of Holstein Friesian × Sahiwal crossbred dairy bulls (N = 557) were analysed using different statistical models. A present study revealed that the biological rhythm of reproduction oscillated almost in parallel to the annual changes of natural photoperiods even in non-seasonal breeding species like cattle bulls. Semen traits diminished to the lowest in winter solstice (WS ± 45 days), progressively increased with the rising day length of spring (vernal equinox ± 45 days), reached a peak in summer solstice (SS ± 45 days), and then gradually reduced with decreasing photoperiod of the autumn equinox (AE ± 45 days). From summer solstice to winter solstice, sperm concentration reduced by 90.53 million/ml (8.85%), total sperm count/ejaculate decreased by 785 million (13.87%), total motile sperm count/ejaculate reduced by 17.59%, and total post-thaw motile sperm counts/ejaculates diminished by 38.64%. In short-duration photoperiods (≤ 12 h), bulls had a significantly (P < 0.01) higher incidence of major, minor, tail abnormality and total aberrant sperm% compared to that of long-duration photoperiods (> 12 h). Solstice equinox–based seasonal classification provided better insight into photoperiodicity on bulls' semen quality and sperm traits as compared to conventional meteorological classification of seasons. It was concluded that photoperiods affect sperm productivity, semen quality, and sperm morphology in non-seasonal breeding species like dairy bulls, maintained at transitional latitude (29° N) tropical climate. Bulls' reproductive ability was more influenced by the phases of increasing/decreasing day length duly primed by climax/trough of photoperiods, compared to mere long/short duration of photoperiods. [ABSTRACT FROM AUTHOR]
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- 2022
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6. Performance evaluation of a locally designed stepped solar distillation-cum-active drying unit.
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Manchanda, Himanshu and Kumar, Mahesh
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HEAT transfer coefficient , *SOLAR collectors , *HEAT convection , *SOLAR stills , *FLOW coefficient , *POTATOES , *ENERGY consumption , *COST analysis - Abstract
Experiments have been performed on an innovative stepped solar distillation-cum-active drying unit (SSD-ADU). The basin of the distillation unit is made in the stepped form and its underneath part works as a drying unit which is integrated with a solar flat plate collector. Thermal analysis of the SSD-ADU has been performed at water flow rates of 50 and 65 mL min−1 in the distillation unit for drying ginger. The developed unit has been found to perform better at lower water flow rate for which the drying of bitter gourd and potato slices has also been tested. The average values of internal and external heat transfer coefficients at lower flow rate for distillation unit are found to be 121.20 and 18.95 Wm−2 °C, respectively. The average values of convective heat transfer coefficients for the drying of ginger, bitter gourd and potato slices have been evaluated as 5.24, 4.67 and 5.46 Wm−2 °C, respectively. The energy efficiency, exergy efficiency and daily distillate output of the distillation system at lower flow rate have been observed 15%, 28% and 12% higher than at other given flow rate. Experimental uncertainty, efficiency of solar collector and cost analysis of SSD-ADU have also been evaluated. [ABSTRACT FROM AUTHOR]
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- 2022
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7. Image processing techniques to estimate weight and morphological parameters for selected wheat refractions.
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Sharma, Rohit, Kumar, Mahesh, and Alam, M. S.
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IMAGE processing , *FEATURE extraction , *ESTIMATION theory , *DEEP learning , *PYTHON programming language , *GRAIN , *WHEAT - Abstract
The geometric and color features of agricultural material along with related physical properties are critical to characterize and express its physical quality. The experiments were conducted to classify the physical characteristics like size, shape, color and texture and then workout the relationship between manual observations and using image processing techniques for weight and volume of the four wheat refractions i.e. sound, damaged, shriveled and broken grains of wheat variety PBW 725. A flatbed scanner was used to acquire the images and digital image processing method was used to process the images and output of image analysis was compared with the actual measurements data using digital vernier caliper. A linear relationship was observed between the axial dimensions of refractions between manual measurement and image processing method with R2 in the range of 0.798–0.947. The individual kernel weight and thousand grain weight of the refractions were observed to be in the range of 0.021–0.045 and 12.56–46.32 g respectively. Another linear relationship was found between individual kernel weight and projected area estimated using image processing methodology with R2 in the range of 0.841–0.920. The sphericity of the refractions varied in the range of 0.52–0.71. Analyses of the captured images suggest ellipsoid shape with convex geometry while the same observation was recorded by physical measurements also. A linear relationship was observed between the volume of refractions derived from measured dimensions and calculated from image with R2 in the range of 0.845–0.945. Various color and grey level co-variance matrix texture features were extracted from acquired images using the open-source Python programming language and OpenCV library which can exploit different machine and deep learning algorithms to properly classify these refractions. [ABSTRACT FROM AUTHOR]
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- 2021
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8. Novel and known miRNAs in zebu (Tharparkar) and crossbred (Karan-Fries) cattle under heat stress.
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Kumar, Mahesh, Noyonika, Aggarwal, Anjali, and Kaul, Gautam
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MICRORNA , *MITOGEN-activated protein kinases , *NON-coding RNA , *ZEBUS , *CATTLE crossbreeding , *CATTLE - Abstract
MicroRNAs (miRNAs) are small single-stranded non-coding RNAs that act as the master regulator of animal growth and development. RNA-RNA interaction is an important mechanism of gene regulation during biotic and abiotic stress. Heat stress (HS) is one of the most important abiotic factors which affect the growth, milk yield and reproductive health of the dairy animals. In the present investigation, we identified 387 known and 77 novel miRNAs from Tharparkar (TH) and Karan Fries (KF) cattle under HS condition. Family distribution analysis showed the identified miRNAs belong to more than 15 different families in which miR-2284 was the most abundant. We identified 42,350 targets for the known miRNAs reported in cattle. Pathway analysis of the identified targets showed most of the target genes were involved in cancer, mitogen-activated protein kinase (MAPK) signaling, calcium signaling, Ras signaling, and cAMP signaling pathways. Differential gene expression showed more than 344 miRNAs changed their expression significantly between control and HS condition. Heat map was generated for the top 20 most up and downregulated miRNAs. Ten miRNAs were validated using qRT-PCR to be heat responsive, based on read count value and differential gene expression. These novel miRNAs are new addition to the miRNA database of cattle. This study provides an overview of miRNA profile and their interaction with the target genes which leads to further understanding in deciphering the thermotolerance mechanism in cattle. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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9. Topological insulator Bi2Se3 as a tunable crystal for terahertz frequency generation.
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Sharma, Prince, Kumar, Mahesh, and Awana, V. P. S.
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TOPOLOGICAL insulators , *HOT carriers , *TERAHERTZ materials , *CRYSTALS , *SINGLE crystals , *REFLECTANCE spectroscopy - Abstract
The dynamical behavior of carrier electrons varies from metals to insulators depending upon their intrinsic energy levels. The anomalous behavior of carriers in topological insulators makes it a prior candidate for numerous applications in the field of spintronics, optoelectronics, terahertz generation, and detection. This article reports the excited state dynamics of a thin shining flake of Bi2Se3 single crystal in which the kinetic profile is extensively analyzed. The ultrafast carrier dynamics of this crystal were studied over a wide NIR spectral range with several optical excitations using ultrafast transient reflectance spectroscopy. The thermalization of generated hot carriers due to the implication of pump beam and their relaxation pathways through different energy levels are predicted. The signal comprises optical (1–10 ps) and acoustic (10–50 ps) coherent phonon vibrations in the crystal. The FFD (filtering high-frequency component followed by fitting data) analysis is carried out to investigate the terahertz frequency generation dependence. This article has clearly shown the tunability of terahertz generation with external electromagnetic excitations and probe radiations. [ABSTRACT FROM AUTHOR]
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- 2021
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10. A systematic experimental study of pre-compound emission in α-particle induced reactions on odd mass nuclei A = 103–123.
- Author
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Sharma, Manoj Kumar, Kumar, Mahesh, Shuaib, Mohd., Majeed, Ishfaq, Asnain, M. Shariq, Sharma, Vijay R., Yadav, Abhishek, Singh, Pushpendra P., Singh, Devendra P., Singh, B. P., and Prasad, R.
- Abstract
The compound and pre-compound emission processes have been established as two main competing de-excitation modes of an excited nucleus by-dint-of evaporation and emission of light fast particles in low energy α -induced reactions, respectively. An existence of the plenty experimental data on above established processes for a wide range of mass nuclei coerces to drive for some systematic trends in such reactions with excitation energy and mass number (A). Present work is an attempt to develop a systematics on the pre-compound emission process by analysing consistent experimental cross-section data of α -particle induced reactions on odd Z and odd A isotopic target nuclei viz., 103 Rh, 107 Ag, 109 Ag, 113 In, 115 In, 121 Sb, and 123 Sb, respectively. The analysis of data indicates sarcastic deviation in the experimental cross-section data with respect to calculations performed by the statistical Monte-Carlo code pace4 beyond the peak region. Such deviation becomes more prominent towards tail portion of excitation functions, which is regarded as a significant contribution of the pre-compound emission process. Observed energy dependent uniformity of such deviation for all studied reactions gives a clue for existing some systematics on concerning process with atomic mass number (A). Present study is an extension of previous work [Eur. Phys. J. A 54, 205 (2018)], but rather in more precise way for nearby isotopic target mass nuclei 107 Ag, 109 Ag, 113 In, 115 In, 121 Sb, and 123 Sb, respectively, where role of the Coulomb barrier V b and target deformation is found to be significantly important in the systematic decay of excited nuclei through emission of light fast particles in pre-compound process with mass number (A). [ABSTRACT FROM AUTHOR]
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- 2020
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11. Transient analysis of viscoelastic fluid past a semi-infinite vertical cylinder with respect to the Deborah and Hartmann numbers.
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Kumar, Mahesh, Reddy, G. Janardhana, and Ragoju, Ravi
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NEWTONIAN fluids , *TRANSIENT analysis , *FLOW visualization , *NATURAL heat convection , *CRANK-nicolson method , *ENTHALPY , *NON-Newtonian flow (Fluid dynamics) , *HYDRAULIC cylinders - Abstract
This article investigates the visualizations of heatlines in a natural convection magnetohydrodynamic flow from a vertical cylinder via heat function concept. Fluid is electrically conducting in the existence of an applied magnetic field. The constitutive equations of time-dependent, coupled and highly nonlinear Jeffrey fluid model are evaluated mathematically by utilizing well-organized unconditionally stable finite-difference Crank–Nicolson method. Simulated results are given for several values of Deborah number and Hartmann number to present interesting aspects of the solution of the flow variables, friction factor and heat transfer rate. Results specify that required time to achieve time-independent state rapidly rises with the boosting values of Hartmann number. Boundary-layer flow visualization has been made using heatlines, isotherms and streamlines to perceive the understanding of heat and fluid flow. It is noticed that heat function value reduces for augmenting Hartmann number and also for all smaller physical parameter values and these heatlines become closer to the hot wall. It is also remarked that the hydromagnetic flow-field profiles concerning the Newtonian fluid show a different pattern from that of non-Newtonian Jeffrey fluid. [ABSTRACT FROM AUTHOR]
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- 2020
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12. Bejan flow visualization of free convection in a Jeffrey fluid from a semi-infinite vertical cylinder: Influence of Deborah and Prandtl numbers.
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Kumar, Mahesh, Reddy, G. Janardhana, and Bég, O. Anwar
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FLOW visualization , *PRANDTL number , *FREE convection , *ENTHALPY , *NEWTONIAN fluids , *FINITE difference method - Abstract
This article studies the pattern of heat lines in free convection non-Newtonian flow from a semi-infinite vertical cylinder via Bejan's heat function concept. The viscoelastic Jeffrey fluid model is employed. The time-dependent, coupled, nonlinear conservation equations for momentum and energy (heat) are solved computationally with the unconditionally stable finite difference Crank–Nicolson method. Extensive graphical results are presented for the influence of Deborah number (viscoelastic parameter) and Prandtl number (with ranges 0–0.8 and 0.68–7.2, respectively) on thermal and flow characteristics including time histories of overall skin friction and heat transfer rate. Lower values of Deborah number indicate that the material acts in a more fluid-like manner, whereas the higher values of Deborah number correspond to the material showing characteristics more associated with a solid. The solutions indicate that the time taken for the flow-field variables to achieve the steady state is increased with higher values of Deborah number. Boundary flow visualization is presented using heat lines, isotherms and streamlines. It is observed that as Deborah number increases the intensity of heat lines increases and they tend to deviate from the hot cylindrical wall. Furthermore, the flow-field variables for the Newtonian fluid case exhibit a significantly different pattern from that of Jeffrey fluid. [ABSTRACT FROM AUTHOR]
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- 2019
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13. Paediatric parenchymal neurocysticercosis with pleomorphic clinico-radiological presentations: a case series.
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Kumar, Sanjay, Rana, Radhamohan, Kumar, Mahesh, and Yadav, Aakash
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NEUROCYSTICERCOSIS , *NUCLEAR magnetic resonance spectroscopy , *HELMINTHIASIS , *CHILD patients , *ETHNICITY ,CENTRAL nervous system infections - Abstract
Background: Neurocysticercosis (NCC) is thought to be the most common helminthic infection of central nervous system in India. In children, it has pleomorphic clinical and radiological presentations depending on location and stage of lesion. Solitary cystic granuloma appearing as a single ring enhancing lesion is the most frequently encountered neuroimaging finding in patients with neurocysticercosis or tuberculoma in India. This series reports unusual clinico-radiological aspects of pediatric neurocysticercosis patients of Asian ethnicity. Case presentation: In the present case series, we have described socio-demographic and clinico-radiological profile of eight cases of neurocysticercosis with parenchymal lesions in varying stages of development. Among these two had single discrete ring enhancing lesion (SDREL), two had single conglomerated ring enhancing lesion (SCREL), and five cases reported to have multiple ring enhancing lesions (MREL). Two cases with recurrent neurocysticercosis have been reported which is quite rare. Magnetic resonance spectroscopy helps to differentiate between neurocysticercosis and tuberculoma and may avoid brain biopsies or unnecessary anti-tubercular treatment. Magnetic resonance spectroscopy (MRS) was done in three cases with findings of absence of lipid peak and choline/creatinine ratio less than 1.2. Conclusion: Despite the advances in neuroimaging, accurate diagnosis of NCC is still sometimes difficult, which is related to the pleomorphic nature of disease and significant overlapping features with tuberculoma. A combination of proper diagnostic criteria and neuroimaging findings are helpful in making the diagnosis without invasive and potentially harmful investigations in paediatric patients. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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14. Assimilates mobilization, stable canopy temperature and expression of expansin stabilizes grain weight in wheat cultivar LOK-1 under different soil moisture conditions.
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Kumar, Mahesh, Raina, Susheel, Govindasamy, Venkadasamy, Singh, Ajay, Choudhary, Ram, Rane, Jagadish, and Minhas, Paramjit
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GRAIN development , *WHEAT yields , *DEFOLIATION , *GENE expression , *WHEAT varieties , *EXPANSINS - Abstract
Background: Grain yield of wheat is primarily determined by both grain number and grain weight, which often influence each other in response to environmental stimuli. Some of the genotypes are capable of maintaining high single grain weight (SGW) across the environments. Understanding mechanisms and factors associated with the superiority of such genotypes over others is necessary to enhance productivity of wheat. Results: Experiments were conducted to elucidate the physiological basis of high SGW of LOK-1, a wheat cultivar grown in dry and hot environments in the central and peninsular zones of India. SGW of LOK-1 was least affected by removal of spikelets indicating little competition between the grains within the spike for assimilates. Reduction in SGW due to defoliation was less and the contribution of stem reserves to the grain development was high in LOK-1 relative to other cultivars. It seems that high level of expression of genes such as expansin (TaExpA6) contributes to the high SGW of LOK-1. Conclusions: Source was not a limiting factor for grain growth of LOK-1 in contrast to other cultivars, whereas sink appeared to be a limiting factor in recently released/identified cultivars. Differences in the amounts of water soluble stem carbohydrate reserves translocated to grain could be one of the factors contributing to higher grain weight in LOK-1. High level expression of TaExpA6, one of the genes contributing to the elongation of endosperm, seems to be crucial for grain growth in wheat. [ABSTRACT FROM AUTHOR]
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- 2017
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15. Gamma radiation protects fruit quality in tomato by inhibiting the production of reactive oxygen species (ROS) and ethylene.
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Kumar, Mahesh, Ahuja, Sumedha, Dahuja, Anil, Kumar, Raj, and Singh, Bhupinder
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GAMMA rays , *FRUIT quality , *REACTIVE oxygen species , *ETHYLENE , *ELECTROMAGNETIC waves , *MAGNETIC fields , *SHELF-life dating of food - Abstract
Experiments were conducted to examine the individual and combined effect of two different electromagnetic energies, i.e., gamma ray viz 0.1, 0.5 and 1 kGy and static magnetic field (50 mT for 1 h) and their combination (0.5 kGy + 50 mT) on the shelf life of tomato and evaluates the biochemical attributes that influence the fruit ripening and fruit quality. Magnetic field application either alone or in combination with gamma irradiation was not effective in delaying the ripening process. Gamma ray exposed fruits at 0.5 and 1 kGy showed an extended shelf life due to delayed fruit ripening and reduced lycopene synthesis and ethylene production. Efficient ROS scavenging ability and consequent reduction in oxidative damage in the irradiated treatment may cause favorable biochemical changes to facilitate delayed ripening of the tomato fruits. [ABSTRACT FROM AUTHOR]
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- 2014
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16. Metabolic and biochemical changes caused by gamma irradiation in plants.
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Ahuja, Sumedha, Kumar, Mahesh, Kumar, Pankaj, Gupta, V., Singhal, R., Yadav, Achchelal, and Singh, Bhupinder
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BIOCHEMISTRY , *RADIOISOTOPES , *NUCLEAR accidents , *PHYSIOLOGICAL effects of gamma rays , *FOOD chains , *RADIATION workers - Abstract
Applications involving radioisotopes and radiations reveal a great promise particularly for the welfare of the society. However, in the event of a nuclear accident, the direct and indirect effect of radionuclide and radiation transfers in soil-plant-air environment are envisaged on almost all the components of the food chain. It also assumes significance as we often overlook the fact that radiations, emitted by any radioisotope although cannot be seen or felt, interacts with matter and could alter its biochemical, biophysical and biological characteristics. The interaction of ionizing radiation with human body and consequent biological effects are well characterized and quantified using data derived from the radiation workers and/or the nuclear accidents around the world. However, radiation impact on agriculture viz a viz economic productivity are not well understood and available data is scanty, scattered and inconclusive. At the plant level the effects could be visualized at morphological, biochemical, physiological and/or biophysical levels, where the magnitude of the effected change depends heavily on the exposure dose, soil, farm management and other environmental variables. This review attempts to collate and critically analyze the available researches on how the ionizing radiation might interact with crops at the whole plant or tissue or cell level to affect economic yield under various edaphic variables where not only the productivity but also the quality of the agri-produce may become vulnerable. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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17. Catalytic effect of bases in impregnation of guanidine nitrate on Poplar ( Populus) wood.
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Arora, Sanjiv, Kumar, Mahesh, and Kumar, Mahender
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CATALYSTS , *GUANIDINES , *AQUEOUS solutions , *POPLARS , *FLAMMABILITY , *SCANNING electron microscopy , *THERMAL analysis - Abstract
Wood, one of the flammable material, was treated with aqueous solution of guanidine nitrate (GUN) and also with small amount of bases like N, N-dimethylformamide, 4-dimethylaminopyridine, pyridine, and triethylamine in the treating solution. These bases catalyze the impregnation of GUN as indicated by increase in mass gain percentage, elemental analysis, and scanning electron microscopy. To study their thermal behavior, dynamic thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis under nitrogen atmosphere have been applied from ambient temperature to 973 K on all samples, at multiple linear heating rates 2.5, 5, 10, and 20 K min. Non-isothermal, 'model free' iso-conversional multiple heating rate methods, Ozawa-Flynn-Wall (O-F-W) and modified Coats-Redfern are used to calculate activation energy of samples. The activation energy of samples is found in the range 109-208 kJ mol. Thermal parameters like overall pyrolysis duration, maximum mass loss rate, corresponding to DTG peak maximum and percentage char yield calculated at 873 K from TG curves are used to appraise the flammability of samples. Also, flammability of samples is determined by reliable methods namely limiting oxygen index and underwriters laboratories 94 (UL 94) test. The aforesaid study indicates that base catalyzed impregnated samples are less flammable than those impregnated with only GUN and untreated ones. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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18. Phase evolution studies of sol-gel derived lead zirconate titanate (PZT) nanopowder using X-ray diffraction and X-ray photoelectron spectroscopy.
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Sachdeva, Anupama, Kumar, Mahesh, Luthra, Vandna, and Tandon, R.
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PHASE equilibrium , *CHEMICAL processes , *TITANATES , *NANOSTRUCTURED materials , *POWDER metallurgy , *X-ray diffraction , *X-ray photoelectron spectroscopy , *TEMPERATURE effect , *PEROVSKITE - Abstract
We report here the formation of single phase lead zirconate titanate (PZT) nanopowder with composition Pb(ZrTi)O and average crystallite size 12-20 nm, synthesized by sol-gel process. The phase evolution of PZT gel powder, heat treated at temperatures 550, 650 and 800°C was monitored by X-ray diffraction (XRD) and X-ray photo-electron spectroscopy (XPS). The high resolution XPS spectra of Pb4f, Zr3d, Ti2p and O1s show that PZT with pure perovskite structure is obtained at 800°C while at lower temperatures pyrochlore phase co-exists with perovskite phase. The XRD results also support this analysis. We have also identified the pyrochlore phase using XPS by analyzing the corresponding variations in the FWHM values, peak positions and the separation between the spin doublets of Pb, Zr and Ti associated with it. The composition of the final powder obtained with pure perovskite structure is calculated and is close to the designed value. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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19. Kinetics of self-assembled InN quantum dots grown on Si (111) by plasma-assisted MBE.
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Kumar, Mahesh, Roul, Basanta, Bhat, Thirumaleshwara, Rajpalke, Mohana, Sinha, Neeraj, Kalghatgi, A., and Krupanidhi, S.
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CHEMICAL kinetics , *MOLECULAR self-assembly , *INDIUM compounds , *QUANTUM dots , *NITRATES , *MOLECULAR beam epitaxy , *PHOTOLUMINESCENCE , *SEPARATION (Technology) - Abstract
One of the scientific challenges of growing InN quantum dots (QDs), using Molecular beam epitaxy (MBE), is to understand the fundamental processes that control the morphology and distribution of QDs. A systematic manipulation of the morphology, optical emission, and structural properties of InN/Si (111) QDs is demonstrated by changing the growth kinetics parameters such as flux rate and growth time. Due to the large lattice mismatch, between InN and Si (~8%), the dots formed from the Strannski-Krastanow (S-K) growth mode are dislocated. Despite the variations in strain (residual) and the shape, both the dot size and pair separation distribution show the scaling behavior. We observed that the distribution of dot sizes, for samples grown under varying conditions, follow the scaling function. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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20. Self-assembled flower-like nanostructures of InN and GaN grown by plasma-assisted molecular beam epitaxy.
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Kumar, Mahesh, Bhat, T., Rajpalke, M., Roul, B., Misra, P., Kukreja, L., Sinha, Neeraj, Kalghatgi, A., and Krupanidhi, S.
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MOLECULAR self-assembly , *GALLIUM nitride , *INDIUM , *NITRIDES , *PHOTOLUMINESCENCE , *NANOSTRUCTURES , *MOLECULAR beam epitaxy , *X-ray photoelectron spectroscopy , *EXCITON theory - Abstract
Nanosized hexagonal InN flower-like structures were fabricated by droplet epitaxy on GaN/Si(111) and GaN flower-like nanostructure fabricated directly on Si(111) substrate using radio frequency plasma-assisted molecular beam epitaxy. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the crystallinity and morphology of the nanostructures. Moreover, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to investigate the chemical compositions and optical properties of nano-flowers, respectively. Activation energy of free exciton transitions in GaN nano-flowers was derived to be ∼28.5 meV from the temperature dependent PL studies. The formation process of nano-flowers is investigated and a qualitative mechanism is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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21. Growth and characterization of high resistivity c-axis oriented ZnO films on different substrates by RF magnetron sputtering for MEMS applications.
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Singh, Ravindra, Kumar, Mahesh, and Chandra, Sudhir
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ZINC oxide thin films , *MAGNETRONS , *RADIO frequency , *SCANNING electron microscopy , *PIEZOELECTRIC materials , *MICROELECTROMECHANICAL systems , *ANNEALING of crystals - Abstract
In the present work, we report the deposition of high resistivity c-axis oriented ZnO films by RF magnetron sputtering. The deposition parameters such as RF power, target-to-substrate spacing, substrate temperature, and sputtering gas composition affect the crystallographic properties of ZnO films, which were evaluated using XRD analysis. The self-heating of the substrate in plasma during film deposition was investigated and we report that highly “c-axis oriented” ZnO thin films can be prepared on different substrates without any external heating under optimized deposition parameters. The post-deposition annealing of the film at 900 °C for 1 h in air ambient increases the intensity of (002) peak corresponding to c-axis orientation in addition with the decrease in full width at half maxima (FWHM). Bond formation of ZnO was confirmed by FTIR analysis. Grains distribution and surface roughness have been analyzed using SEM and AFM. The DC resistivity of the films prepared under different deposition conditions was measured using MIS/MIM structures and was found to be in the range of 1011–1012 Ω cm at low electric field of 104 V/cm. The ZnO film of 1 μm thickness has transmittance of over 85% in the visible region. Applications of these films in MEMS devices are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
22. Proton magnetic resonance spectroscopy with a body coil in the diagnosis of carcinoma prostate.
- Author
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Kumar, Rajeev, Kumar, Mahesh, Jagannathan, N. R., Gupta, Narmada P., and Hemal, Ashok K.
- Subjects
- *
PROTON magnetic resonance spectroscopy , *PROSTATE cancer , *HYPERTROPHY , *DIAGNOSIS , *BIOPSY , *DIFFERENTIAL diagnosis - Abstract
We evaluate the feasibility of proton magnetic resonance spectroscopy (1H MRS) using a spine coil receiver (body coil) in the diagnosis of carcinoma prostate. Seventeen patients with biopsy-proven prostate carcinoma, five patients of benign prostatic hyperplasia (BPH) and five healthy young volunteers underwent 1H MRS investigation. MRS was performed at 1.5 Tesla using a spine receiver coil for signal reception. In vivo citrate levels are reported as a ratio of citrate peak area to the sum of the areas of choline and creatine peak. MRS spectrum with good sensitivity and signal to noise (S/N) ratio was obtained in all 27 subjects. The citrate to creatine plus choline ratio was 0.31±0.25 in patients with cancer, 1.43±0.58 in BPH and 2.16±0.56 in controls. The difference in ratios between cancer and BPH and cancer and control was statistically significant (p<0.01). Within the cancer group, there was a statistically significant decline in levels with higher-grade malignancy (p<0.05). There were no complications of the procedure. There is a statistically significant decline in the ratio of citrate to choline plus creatine in the regions of cancer prostate when compared with BPH or normal control. The study demonstrates that MRS data can be reliably acquired using a spine coil receiver. MRS may also play a role in differentiating well-differentiated tumors from the anaplastic variety. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
23. DB-CMT: A New Concurrent Multi-path Stream Control Transport Protocol.
- Author
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Verma, Lal Pratap, Sharma, Varun Kumar, Kumar, Mahesh, Kanellopoulos, Dimitris, and Mahanti, Aniket
- Abstract
Stream Control Transmission Protocol (SCTP) exploits multiple network interfaces to provide multi-streaming and data chunk ordering in a stream. An extended feature of SCTP, i.e., Concurrent Multi-path Transfer (CMT), bids concurrent data transmission in a multi-path data transfer environment and guarantees bandwidth aggregation, load sharing, robustness, and reliability. In such an environment, the paths usually have distinct characteristics (i.e., delay, Packet Loss Rate (PLR), and bandwidth). Thus, data chunks are received out-of-ordered at the destination. As a result, CMT causes excessive receiver buffer blocking and unnecessary congestion window (cwnd) reductions. Also, during the selection of the retransmission destination path (to resend a lost data chunk), CMT does not take into account vital Quality of Service (QoS) parameters such as the PLR of a path under consideration. This paper introduces a new Delay-Based Concurrent Multi-path Transfer (DB-CMT) approach that transmits data on multiple paths according to their delay. In this scheme, we present a Delay-Based Data chunk Scheduling Policy (DB-DSP), a Retransmission Path Selection Policy (RTX-CL), and a new Delay-Based Fast Retransmission Policy (DB-FRP). The simulation results show that the DB-CMT’s RTX-CL policy performs better than the well-known RTX-CWND and RTX-LOSSRATE retransmission schemes. Also, the overall performance of DB-CMT witnesses improved throughput, fewer timeouts, and reduced File Transfer Time (FTT) performances. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. Insight into the Biomass-Based Briquette Generation from Agro-Residues: Challenges, Perspectives, and Innovations.
- Author
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Ali, Arshad, Kumari, Meena, Manisha, Tiwari, Sumit, Kumar, Mahesh, Chhabra, Deepak, and Sahdev, Ravinder Kumar
- Subjects
- *
BRIQUETS , *RENEWABLE energy sources , *WASTE products as fuel , *LITERATURE reviews , *MATHEMATICAL optimization , *HYDRAULIC presses - Abstract
Turning biomass waste into briquettes using densification techniques is one of the most promising steps toward mitigating biomass waste pollution and fuel issues in developing countries. Despite the continuous growth of scientific output over the past few decades, only a limited amount of information is available in the literature on biomass briquette optimization and mathematical modeling, as well as the physiochemical characterization of biomass feedstocks and briquette operating variables. In light of this gap in the current literature, this study summarizes the current state of the art and recent advances in biomass-based briquettes generated from agro-residues as an alternative source of clean energy. The primary research method for this study is literature review and conceptual modeling. First, many densification processes, such as piston press, screw press, roller press, hydraulic press, and quality variables such as ash content, calorific value, moisture content, density, compressive strength, shatter index, etc., are thoroughly discussed and compared. Then characteristics of different biomass wastes are studied, together with process parameters, including temperature, type of binder used, particle size, and influence on densification process choice. The current evaluation concentrated on the mathematical modeling and optimization of the briquetting technology and the usefulness of briquettes in applications for heating, cooking, and energy production. Overall, this manuscript will help new researchers understand the basic methodology, classification, limitations, and future perspective of briquetting technology in the production of solid biofuels. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. An adaptive multi-path data transfer approach for MP-TCP.
- Author
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Verma, Lal Pratap, Sharma, Varun Kumar, Kumar, Mahesh, and Mahanti, Aniket
- Subjects
- *
TCP/IP , *FILE transfer (Computer science) , *DIGITAL signal processing , *INTERNET protocols - Abstract
Multi-path Transmission Control Protocol (MP-TCP) Coupled Congestion Control algorithm focuses on amalgamating the increased BandWidth (BW) of multiple available links while avoiding MP-TCP's higher aggressiveness in comparison to usual TCP flows on every utilized link. Therefore, this leads to exceedingly conventional behavior when the network paths do not share a congested link. Further, the situation worsens when the network paths possess varying characteristics (i.e., available BW, Packet Loss Rate (PLR), and delay), leading to incurring overheads such as higher re-ordering, buffer-blocking, and needless retransmissions in the network. We observe that the presently implemented MP-TCP scheduler suffers from lower channel utilization due to its conventional congestion window (cwnd) adaptation scheme. As a result, the protocol compromises application-level throughput performance. To address these issues, we propose an Adaptive-Data Scheduling Policy (A-DSP), which dynamically adjusts the cwnd growth according to the paths' Round Trip Time (RTT) variations. To regulate the transmission rate of each path concerning its assessed RTT variation, we design and implement an adaptive fast retransmission policy as well. The evaluations indicate that A-DSP decreases the File Transfer Time by over 50% compared to the MP-TCP scheduler. We also observe throughput performance gains of up to 46%, 19%, and 34% for different PLR, BW, and path delay values, respectively, compared to MP-TCP. Moreover, A-DSP also offers considerable performance improvement compared to other multi-path approaches. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
26. Study of entropy generation in transient hydromagnetic flow of couple stress fluid due to heat and mass transfer from a radiative vertical cylinder.
- Author
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Reddy, G Janardhana, Kumar, Mahesh, and Rani, H P
- Subjects
- *
MASS transfer , *RADIATIVE transfer , *HYDRAULIC couplings , *ENTHALPY , *ENTROPY - Abstract
Radiative–convective flow studies find wide range of applications in furnace design, solar fans, photochemical reactors, turbid water bodies, etc. The present article focusses on unsteady radiative–convective hydromagnetic couple stress fluid (CSF) flow from a vertical cylinder using the thermodynamic concept. The obtained governing equations of the present model are resolved by a well-organised numerical scheme. The unsteady nature of friction, entropy, coefficients of heat and mass transfer (HMT) along with the time-independent state pattern of flow-field profiles, are shown graphically for distinct values of governing radiation parameter, magnetic parameter, concentration parameter, and constant parameter to display important aspects of the solution. To analyse the HMT process in a 2D domain, Bejans flow visualisation is considered along with isotherms, streamlines, and isoconcentration lines. The Bejans HMT flow visualisation shows that the heat and mass function contours are denser in the foremost verge of the hot surface of the cylinder compared to other contours. The result indicates that the entropy generation (EG) parameter increases with decreasing values of radiation and magnetic parameters. Also, the entropy parameter increases for increasing values of concentration parameter or constant parameter. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
27. Thermo-physical properties of paraffin/TiO2 and sorbitol/TiO2 nanocomposites for enhanced phase change materials: a study on the stability issue.
- Author
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Saroha, Jyoti, Mehra, Sonali, Kumar, Mahesh, and Sharma, Shailesh Narain
- Subjects
- *
LATENT heat of fusion , *PHASE change materials , *HEAT storage , *THERMAL conductivity , *HEAT capacity , *LATENT heat - Abstract
Recently, the demand for an accurate and precise determination of the properties of phase change materials (PCM) has increased considerably owing to the dependence of various applications based on latent heat storage (LHS). As reported earlier, PCM has a higher latent heat of fusion and is the cheapest material to store thermal energy. Still, it has poor thermal conductivity and less heat storage retentivity. For this reason, there is a significant interest in PCM-nanoparticles composites because the incorporation of nanoparticles can enhance the thermal properties of PCM. In the present work, TiO2 NPs were synthesized and incorporated with paraffin and sorbitol (PCM) by varying their mass concentration (0, 5, 10, and 20%) to study and compare the thermal properties of NCs. Different characterizations such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and melting temperature testing of nanocomposites by temperature variation method were studied and analyzed. An appreciable decrement in melting point of 19.19, 27.59, 18.57, and 23.89% from 0 to 20% TiO2 concentrations in paraffin and sorbitol was observed from the temperature variation and DSC results, respectively. TGA/DTG results show minimum wt% loss of 57.76% at 316.24 °C and 90.88% at 317.27 °C calculated for 20 and 10% TiO2 concentrations in sorbitol and paraffin, respectively, which corresponds to the thermal stability of NCs. It was verified by both the methods that melting point decreases linearly with an increase in the concentration of NPs in PCM, which further corresponds to the increment in thermal conductivity and thermal storage capacity. Sorbitol exhibits better stability with TiO2 than paraffin as it consists of low strain, less weight loss, and more thermal compatibility. Uncertainty in the determination of the melting point temperature from temperature variation test method and DSC measurements can mainly be ascribed to the difference in the polarity of paraffin/TiO2 and Sorbitol/TiO2 nanocomposites and on the boundary conditions during heating and cooling which markedly affects the dispersion quality of TiO2 nanoparticles within the PCM (paraffin, sorbitol) matrix and these aspects have been modeled pictorially. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
28. Drone remote sensing of wheat N using hyperspectral sensor and machine learning.
- Author
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Sahoo, Rabi N., Rejith, R. G., Gakhar, Shalini, Ranjan, Rajeev, Meena, Mahesh C., Dey, Abir, Mukherjee, Joydeep, Dhakar, Rajkumar, Meena, Abhishek, Daas, Anchal, Babu, Subhash, Upadhyay, Pravin K., Sekhawat, Kapila, Kumar, Sudhir, Kumar, Mahesh, Chinnusamy, Viswanathan, and Khanna, Manoj
- Subjects
- *
ARTIFICIAL neural networks , *REMOTE sensing , *MACHINE learning , *WHEAT , *SPECTRAL imaging , *PRECISION farming , *MICROBIAL inoculants - Abstract
Plant nitrogen (N) is one of the key factors for its growth and yield. Timely assessment of plant N at a spatio-temporal scale enables its precision management in the field scale with better N use efficiency. Airborne imaging spectroscopy is a potential technique for non-invasive near real-time rapid assessment of plant N on a field scale. The present study attempted to assess plant N in a wheat field with three different irrigation levels (I1–I3) along with five nitrogen treatments (N0–N4) using a UAV hyperspectral imager with a spectral range of 400 to 1000 nm. A total of 61 vegetative indices were evaluated to find suitable indices for estimating plant N. A hybrid method of R-Square (R2) and Variable Importance Projection (VIP) followed by Variance Inflation Factor was used to limit the best suitable N-sensitive 13 spectral indices. The selected indices were used as feature vectors in the Artificial Neural Network algorithm to model and generate a spatial map of plant N in the experimental wheat field. The model resulted in R2 values of 0.97, 0.84, and 0.86 for training, validation, and testing respectively for plant N assessment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Investigations of effect of hydroxyl-terminated polybutadiene-based polyurethane binders containing various curatives on thermal decomposition behaviour and kinetics of energetic composites.
- Author
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Kumar, Rajesh, Singh, Arjun, Kumar, Mahesh, Soni, Pramod Kumar, and Singh, Vasundhara
- Subjects
- *
METHYLENE diphenyl diisocyanate , *TOLUENE diisocyanate , *ACTIVATION energy , *FURAZANS , *THERMAL stability , *POLYBUTADIENE , *POLYURETHANES - Abstract
An energetic composite of an octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine with a polymer matrix is generally developed to reduce sensitivity, improve mechanical strength and furnish engineering shape. A hydroxyl-terminated polybutadiene (HTPB) and various curatives, namely methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI) and trimethyl-hexamethylene diisocyanate (TMDI), were mixed in 1:1 [NCO]/[OH] equivalent ratio to form polyurethane, and these samples were designated by HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI, respectively. The four kinds of energetic composites were prepared by mixing of an energetic HMX with various HTPB/MDI, HTPB/IPDI, HTPB/TDI and HTPB/TMDI matrices. These composites were studied for the thermal stability by employing thermogravitry analysis (TGA) and found to be almost similar. The kinetic parameters of all kinds of composites were investigated through the isoconversional Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods for the first and second stages of the thermal decomposition using TGA data. The results of the activation energy obtained from the FWO method were analogous to those values obtained from the isoconversional KAS method. In addition, the kinetic parameters were also investigated through isoconversional KAS method using DSC data. The overall values of the activation energy of the HMX/HTPB/MDI, HMX/HTPB/IPDI, HMX/HTPB/TDI and HMX/HTPB/TMDI samples were varied in a range of 168–263, 277–409, 210–421 and 206–324 kJ mol−1 at a constant value of conversion (α = 0.1–0.9), respectively. The results indicated that there was significant variation in the activation energy with varying curative groups in the HTPB-based PU matrices. The compensation effect method was used to calculate the pre-exponential factor. The energetic composites were also investigated for the thermodynamic parameters for formation of the activated complexes and are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
30. Transient entropy analysis of the magnetohydrodynamics flow of a Jeffrey fluid past an isothermal vertical flat plate.
- Author
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Kumar, Mahesh, Reddy, G Janardhana, and Dalir, Nemat
- Subjects
- *
MAGNETOHYDRODYNAMICS , *ENTROPY , *NUSSELT number , *SHEARING force , *GRASHOF number - Abstract
This study presents the analysis of entropy generation concept for unsteady magnetohydrodynamics Jeffrey fluid flow over a semi-infinite vertical flat plate. This physical problem is constituted by transient coupled highly nonlinear equations and is evaluated numerically by using an implicit scheme. The average values of wall shear stress and Nusselt number, entropy generation number and Jeffrey fluid-flow variables are analysed for distinct values of physical parameters at both transient and steady states. The results show that the time needed for achieving a steady state pertaining to the temperature and velocity gets augmented with the increased values of Jeffrey fluid parameter. The results also specify that the entropy generation number increases with the increasing values of Jeffrey fluid parameter, group parameter and Grashof number while the opposite trend is seen for the magnetic parameter. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
31. Proximity induced band gap opening in topological-magnetic heterostructure (Ni80Fe20/p-TlBiSe2/p-Si) under ambient condition.
- Author
-
Singh, Roshani, Maurya, Gyanendra Kumar, Gautam, Vidushi, Kumar, Rachana, Kumar, Mahesh, Suresh, K. G., Panigrahi, Brahmaranjan, Murapaka, Chandrasekhar, Haldar, Arbinda, and Kumar, Pramod
- Subjects
- *
BAND gaps , *QUANTUM interference , *PHYSICAL vapor deposition , *QUANTUM computing , *SPIN-orbit interactions , *ELECTRIC conductivity - Abstract
The broken time reversal symmetry states may result in the opening of a band gap in TlBiSe2 leading to several interesting phenomena which are potentially relevant for spintronic applications. In this work, the quantum interference and magnetic proximity effects have been studied in Ni80Fe20/p-TlBiSe2/p-Si (Magnetic/TI) heterostructure using physical vapor deposition technique. Raman analysis shows the symmetry breaking with the appearance of A21u mode. The electrical characteristics are investigated under dark and illumination conditions in the absence as well as in the presence of a magnetic field. The outcomes of the examined device reveal excellent photo response in both forward and reverse bias regions. Interestingly, under a magnetic field, the device shows a reduction in electrical conductivity at ambient conditions due to the crossover of weak localization and separation of weak antilocalization, which are experimentally confirmed by magnetoresistance measurement. Further, the photo response has also been assessed by the transient absorption spectroscopy through analysis of charge transfer and carrier relaxation mechanisms. Our results can be beneficial for quantum computation and further study of topological insulator/ferromagnet heterostructure and topological material based spintronic devices due to high spin orbit coupling along with dissipationless conduction channels at the surface states. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Pedotransfer functions to estimate soil water content at field capacity and permanent wilting point in hot Arid Western India.
- Author
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Santra, Priyabrata, Kumar, Mahesh, Kumawat, R N, Painuli, D K, Hati, K M, Heuvelink, G B M, and Batjes, N H
- Subjects
- *
SOIL moisture measurement , *ARID regions , *DRY farming , *IRRIGATION water , *LANDSCAPES - Abstract
Characterization of soil water retention, e.g., water content at field capacity (FC) and permanent wilting point (PWP) over a landscape plays a key role in efficient utilization of available scarce water resources in dry land agriculture; however, direct measurement thereof for multiple locations in the field is not always feasible. Therefore, pedotransfer functions (PTFs) were developed to estimate soil water retention at FC and PWP for dryland soils of India. A soil database available for Arid Western India (
N =370) was used to develop PTFs. The developed PTFs were tested in two independent datasets from arid regions of India (N =36) and an arid region of USA (N =1789). While testing these PTFs using independent data from India, root mean square error (RMSE) was found to be 2.65 and 1.08 for FC and PWP, respectively, whereas for most of the tested ‘established’ PTFs, the RMSE was >3.41 and >1.15, respectively. Performance of the developed PTFs from the independent dataset from USA was comparable with estimates derived from ‘established’ PTFs. For wide applicability of the developed PTFs, a user-friendly soil moisture calculator was developed. The PTFs developed in this study may be quite useful to farmers for scheduling irrigation water as per soil type. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
33. Flexible perylenediimide/GaN organic–inorganic hybrid system with exciting optical and interfacial properties.
- Author
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Kumar, Rachana, Kushvaha, Sunil Singh, Kumar, Mahesh, Kumar, Muthusamy Senthil, Gupta, Govind, Kandpal, Kavindra, and Kumar, Pramod
- Subjects
- *
ELECTRON-deficient compounds , *ELECTRON transport , *CHARGE transfer , *OPTOELECTRONICS , *BAND gaps - Abstract
We report the band gap tuning and facilitated charge transport at perylenediimide (PDI)/GaN interface in organic–inorganic hybrid nanostructure system over flexible titanium (Ti) foil. Energy levels of the materials perfectly align and facilitate high efficiency charge transfer from electron rich n-GaN to electron deficient PDI molecules. Proper interface formation resulted in band gap tuning as well as facilitated electron transport as evident in I–V characteristics. Growth of PDI/GaN hybrid system with band gap tuning from ultra-violet to visible region and excellent electrical properties open up new paradigm for fabrication of efficient optoelectronics devices on flexible substrates. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
34. Development of ZnO nanostructure film for pH sensing application.
- Author
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Sharma, Prashant, Bhati, Vijendra Singh, Kumar, Mahesh, Sharma, Rishi, Mukhiya, Ravindra, Awasthi, Kamlendra, and Kumar, Manoj
- Subjects
- *
ZINC oxide synthesis , *ZINC oxide films , *ATOMIC force microscopy , *SCANNING electron microscopes , *ZINC oxide , *RADIOFREQUENCY sputtering , *SURFACE roughness - Abstract
Nanostructured zinc oxide sensing film was deposited on the Si/SiO2/Pt substrate by the RF magnetron sputtering process. The film was characterized by FESEM (field-emission scanning electron microscope) and XRD (X-ray diffraction) for their morphology and structural analysis. The FESEM results show that the film morphology is in nanophase with an average nanostructure size of ~ 50 nm. XRD results show that the film is polycrystalline. The AFM (atomic force microscopy) and Raman spectroscopy were done to analyze the surface roughness and the structural properties of the film, respectively. FTIR (Fourier-transform infrared spectroscopy) was used to analyze the presence of ZnO. Further, the ZnO nanostructure film has been explored for pH sensing for pH (4–12). The sensitivity of the film was found to be 31.81 mV/pH. The drift characteristics of the film were also done to find out the stability of the film. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
35. Multi-trait PGP rhizobacterial endophytes alleviate drought stress in a senescent genotype of sorghum [Sorghum bicolor (L.) Moench].
- Author
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Govindasamy, Venkadasamy, George, Priya, Kumar, Mahesh, Aher, Lalitkumar, Raina, Susheel Kumar, Rane, Jagadish, Annapurna, Kannepalli, and Minhas, Paramjit Singh
- Subjects
- *
SORGHUM , *ENDOPHYTES , *DROUGHTS , *ENTEROBACTER cloacae , *GENOTYPES , *PSYCHOLOGICAL stress , *EFFECT of herbicides on plants , *DROUGHT management - Abstract
Root-tissue colonizing bacteria demonstrated with multiple PGP traits from sorghum plants were identified as Ochrobactrum sp. EB-165, Microbacterium sp. EB-65, Enterobacter sp. EB-14 and Enterobacter cloacae strain EB-48 on the basis of 16S rRNA gene sequencing. Here, the in vivo experiments using ½-MS media and ½-MS media + 15% PEG 8000 (for inducing drought stress) indicated stress tolerance imparting ability of these rhizobacterial endophytes in a non-stay green and senescent genotype (R-16) of sorghum. In the experiment with sterile soilrite mix base, seed bacterization with these isolates showed improved plant growth specifically the roots, in terms of root length (~ 44.2 to 50.8% over controls), root dry weight (~ 91.3 to 99.8% over controls) and root surface area (~ 1 to 1.5 fold over controls) under drought stress. Rhizobacterial endophytes were successful, not only in providing better cellular osmotic adjustment in leaves (≥ 1-fold increase in proline accumulation over controls), but favorable physiological responses like Relative Water Content (RWC) and cell Membrane Stability Index (MSI) in the inoculated plants during the drought stress induction. Up-regulation of drought responsive genes like sbP5CS2 and sbP5CS1 was observed in these endophytes-treated plants as compared to untreated control and Escherichia coli DH5α (negative control)-treated plants. Interestingly, the stress imparting traits of rhizobacterial endophytes, including up-regulation of specific genes, were observed during sorghum seedling growth only under drought stresses. The results of this study lead to the conclusion that the potential endophytic rhizobacterial interactions can contribute to plant growth promotion as well as induced stress tolerance in sorghum. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
36. Research hotspots and development trends in the rubber industry wastewater treatment: a quantitative analysis of literature.
- Author
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Ullah, Ibrar, Naseer, Muhammad Nihal, Zaidi, Asad A., Kumar, Mahesh, Rasool, Urfa, and Kim, Bumjoo
- Subjects
- *
WASTEWATER treatment , *RUBBER industry , *QUANTITATIVE research , *INDUSTRIAL wastes , *WASTE management , *CRUMB rubber - Abstract
Waste management and water scarcity are two unprecedented challenges to humanity. In recent years, steady growth has been observed in the development of different technologies for the treatment of industrial wastewater. However, conducting a quantitative analysis of literature published on rubber wastewater treatment is still a novelty. In this study, bibliometric and content analysis techniques are used to analyse literature related to rubber wastewater, published during the last 5 decades to unearth research trends in this field. For this, the Web of Science database was used to extract 462 relevant records. The parameters analysed in this analysis are annual publication output, publication patterns, leading countries and leading organisations. Furthermore, to map the research trends of the field, content analysis was also performed and the most frequent keywords, as well as research fronts of the field, were highlighted. Results show that about 48% of the literature was published during the last 5 years. Water Science & Technology and Bioresource Technology were spotted as the most famous journals. Furthermore, conducting kinetic studies and using silver nanoparticles, due to their exceptional antimicrobial properties, to enhance overall wastewater treatment performance are found research fronts in this field. The use of membranes to treat rubber wastewater has emerged as a promising option. However, some key challenges such as high installation and maintenance cost, membrane fouling and low membrane efficacy still need to be resolved. Furthermore, mathematical modeling and simulation of membrane technologies require further attention from the research community. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. RETRACTED ARTICLE: Monoaminergic and Nitriergic Modulation for Antidepressant-like Activity of Naringin in Unstressed and Acute Immobilization-Induced Stressed Mice.
- Author
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kumar, Mahesh, Gupta, Arun, Bansal, Vaibhav, Singh, Rajeshwar, and Kumar, Varun
- Subjects
- *
ANTIDEPRESSANTS , *NARINGIN , *LABORATORY mice , *IMMOBILIZATION stress , *DATA analysis ,ANIMAL models of stress - Published
- 2012
- Full Text
- View/download PDF
38. Thermal studies of some biological active oxadiazoles.
- Author
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Arora, Sanjiv, Aneja, Deepak, Kumar, Mahesh, Sharma, Chetan, and Prakash, Om
- Subjects
- *
THERMAL analysis , *BIOACTIVE compounds , *OXADIAZOLES , *SYMMETRY (Physics) , *ORGANIC compounds , *HEATING , *CHEMICAL kinetics , *ANTIBACTERIAL agents , *DRUG activation - Abstract
A series of new unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles ( 3a- d) has been synthesized to evaluate their antibacterial and thermal properties. All compounds have been tested for their in vitro antibacterial activity against two Gram-positive bacteria namely, Staphylococcus aureus and Bacillus subtilis. Among the tested compounds, compound 2-(4-chlorophenyl)-5-(thiophen-2-yl)-1,3,4-oxadiazole ( 3c) has been found to be most potent member having minimum inhibitory concentration. Thermal stability and melting point of compounds have been studied by TG and DSC analysis in air atmosphere at heating rate of 10 °C min. Thermal degradation kinetics of the most potent antibacterial compound 3c has been carried out by multiple heating rate model free kinetic methods namely, Ozawa-Flynn-Wall, modified Coats-Redfern, and Kissinger. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
39. Optimization of deficit irrigation and nitrogen fertilizer management for peanut production in an arid region.
- Author
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Rathore, Vijay Singh, Nathawat, Narayan Singh, Bhardwaj, Seema, Yadav, Bhagirath Mal, Kumar, Mahesh, Santra, Priyabrata, Praveen Kumar, Reager, Madan Lal, Yadava, Narendra Dev, and Yadav, Om Parkash
- Subjects
- *
NITROGEN fertilizers , *PEANUTS , *DEFICIT irrigation , *ARID regions - Abstract
Deficit irrigation (DI) has been emerging as an important technique for enhancing crop water productivity (WP). However, advantage of DI under varying nitrogen (N) application rates remains unclear. Field experiments were conducted during 2012–2014 to investigate the impacts of six irrigation levels[FI (full irrigation), DI10, DI20, DI30, DI40 and DI50, with irrigation amount of 100, 90, 80, 70, 60 and 50% of ETc, respectively) and four N application rates (N0, N10, N20 and N30, with 0, 10, 20 and 30 kg N ha−1, respectively) on WP, yield, quality, and net economic return of peanut in hot arid region of India. We used Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method to obtain the optimal combination of irrigation and N rates. Both irrigation level and nitrogen dose had significant effects on yield and quality parameters examined in the study. Relative to FI, DI40 and DI50 significantly reduced yield (40.2–62.1%), economic benefit (70.8–118.5%), WP (8.2–33.0%), and kernel oil content (7.5–11.9%), but DI20 increased WP by 17.1% with only marginal reduction in economic benefit (2.6%), and yield (3.2%). Compared to N0, the N30 had 1.7, 1.1, and 1.6-folds increased yield, oil content in the kernel, and WP, respectively. Among all treatments, DI0N30 had the greatest yield and net return; DI20N30 had greatest WP and oil content in the kernel. TOPSIS analysis showed that DI20N30 was optimal in balancing of WP, yield, net return, and quality of peanut in northwestern arid India. The results have direct implications for improving irrigation water and N management for irrigated crops in arid regions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
40. Excited-state dynamics of structurally characterized crystal of SnxSb1-x.
- Author
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Sharma, Prince, Sharma, M. M., Kumar, Kapil, Kumar, Mahesh, and Awana, V. P. S.
- Subjects
- *
ALLOYS , *HEAVY metals , *CRYSTALS , *ANALYSIS of heavy metals , *CHARGE carriers , *OPTICAL properties - Abstract
The topological behavior of heavy metal alloys opens a vast area for incredible research and future technology. Here, we extend our previous report about the superconducting properties of Sn0.4Sb0.6 along with the compositional variation of Sn and Sb in SnxSb1-x (with (X = 0.5 and 0.6)) to study the detailed optical properties. Structural and morphological details of grown crystal are carried from the previous study. Further, the samples are excited by a pump of 2.61 eV with a broad probe of 0.77–1.54 eV in the NIR regime for transient reflectance ultrafast studies (TRUS) measurements. The differential reflectance profile shows an unprecedented negative magnitude, and the average power-dependent analysis of this negative trend has been analyzed. This article not only provides evidence of band filling phenomenon in the samples but also shows that with the variation of average power, there is a definite increase in the excited charge carriers, and thereby enhancing the band filling response. The estimated value of the bandgap between the band filled states and valence state is also determined from these studies. The nonlinear properties and bandgap analysis of the studied topological alloys and similar materials help in the advancement of various nonlinear optical applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
41. Room-Temperature Gas Sensors Under Photoactivation: From Metal Oxides to 2D Materials.
- Author
-
Kumar, Rahul, Liu, Xianghong, Zhang, Jun, and Kumar, Mahesh
- Abstract
Highlights: Operations of metal oxide semiconductors gas sensors at room temperature under photoactivation are discussed. Emerging two-dimensional (2D) materials-based gas sensors under light illumination are summarized. The advantages and limitations of metal oxides and 2D-materials-based sensors in gas sensing at room temperature under photoactivation are highlighted.Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap, low power consumption and portable sensors for rapidly growing Internet of things applications. As an important approach, light illumination has been exploited for room-temperature operation with improving gas sensor’s attributes including sensitivity, speed and selectivity. This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field. First, recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted. Later, excellent gas sensing performance of emerging two-dimensional materials-based sensors under light illumination is discussed in details with proposed gas sensing mechanism. Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics. Finally, the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
42. Gallium nitride nanocrystal formation in Si3N4 matrix by ion synthesis.
- Author
-
RAJBHAR, MANOJ KUMAR, RAJAMANI, SARAVANAN, SINGH, S K, SURODIN, SERGEY, NIKOLICHEV, DMITRY, KRYUKOV, RUSLAN, KOROLEV, DMITRY, NIKOLSKAYA, ALYONA, BELOV, ALEXEY, NEZHDANOV, ALEXEY, MIKHAYLOV, ALEXEY, TETELBAUM, DAVID, and KUMAR, MAHESH
- Abstract
Synthesis of nanoparticles in insulators attracts tremendous attention due to their unique electrical and optical properties. Here, the gallium (Ga) and gallium nitride (GaN) nanoclusters have been synthesized in the silicon nitride matrix by sequential ion implantation (gallium and nitrogen ions) followed by either furnace annealing (FA) or rapid thermal annealing (RTA). The presence of Ga and GaN nanoclusters has been confirmed by Fourier-transform infrared, Raman and X-ray photoelectron spectroscopy. Thereafter, the effect of RTA and FA on the conduction of charge carriers has been studied for the fabricated devices. It is found from the current–voltage measurements that the carrier transport is controlled by the space charge limited current conduction mechanism, and the observed values of parameter m (trap density and the distribution of localized state) for the FA and RTA devices are ~2 and ~4.1, respectively. This reveals that more defects are formed in the RTA device and that FA provides better performance than RTA from the viewpoint of opto- and nano-electronic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
43. Growth mechanism and optical properties of Ge nanocrystals embedded in a GeOx matrix.
- Author
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Kalimuthu, Vijayarangamuthu, Kumar, Praveen, Kumar, Mahesh, and Rath, Shyama
- Subjects
- *
OPTICAL properties of nanocrystals , *NANOCRYSTALS , *GERMANIUM , *ANNEALING of metals , *GERMANIUM oxide films - Abstract
Quantum confined germanium (Ge) nanocrystals were synthesized by a thermal annealing of germanium oxide thin films fabricated by an e-beam evaporation method. The nanocrystal formation, structure, and sizes upon annealing are evaluated by a combination of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy studies. Spherical nanocrystals with sizes of around 3 nm and having both diamond and tetragonal phases are formed for an annealing temperature of 500 °C. The thermally induced transformation and phase separation of amorphous germanium oxide to nanocrystalline Ge is discussed using X-ray photoelectron spectroscopy. The bandgap agrees with the calculated values using effective mass approximation. The visible photoluminescence is investigated as a function of the annealing temperature. This disproportionation mechanism of germanium oxide films showing favorable optical properties suggests its scope for forming quantum confined Ge nanocrystals embedded in its amorphous matrix relevant for both electronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
44. Population dynamics of soybean stem fly Melanagromyza sojae (Diptera: Agromyzidae) and its parasitoids in Maharashtra State of India.
- Author
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Fand, Babasaheb B., Gaikwad, Mahesh B., Sul, Nitin T., Kumar, Mahesh, Bhagat, Kiran P., Bal, Santanu K., and Minhas, P.S.
- Subjects
- *
SOYBEAN diseases & pests , *AGROMYZIDAE , *BIOLOGICAL pest control , *PARASITOIDS , *POPULATION dynamics - Abstract
The cryptic nature and lack of consistent biological control of the stem fly, Melanagromyza sojae Zehntner, an emerging pest of soybean, Glycine max (L.) Merrill, necessitated the monitoring and assessment of the impact of the parasitoid complex on seasonal regulation of the pest population. In this paper, we measure and relate, using the host density as a predictor variable, the seasonal density dependence of M. sojae parasitoids and the level of parasitism in soybean fields. The results revealed density dependence of parasitioids. The populations built up concomitant with the host insect, reached their peak during the mid-season, and declined towards the end of the crop season. A complex of 10 species of hymenopteran parasitoids comprising six species from Pteromalidae and one species each from the families Eurytomitidae, Eucoilidae, Braconidae and Eulopidae had a significant impact on M. sojae populations with a peak parasitism of ~50%. The seasonality and relative abundance of parasitoids were explored. Eurytoma sp. (Eurytomitidae) and Gronotoma sp. (Eucoilidae) were the most prevalent parasitoids throughout the season, whereas the pteromalid Sphegigaster sp. was dominant during the mid-season. The modulation of management practices aimed at conservation of these bioagents could improve the biological control of M. sojae populations. We discuss the practicality of several management options aimed at achieving this goal. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
45. SNPs at exonic region of aquaporin-7 ( AQP7) gene may affect semen quality parameters among crossbred bulls.
- Author
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KUMAR, SUSHIL, DEB, RAJIB, SINGH, UMESH, GANGULY, INDRAJIT, MANDAL, D., SINGH, RUPALI, SHARMA, SHEETAL, SENGAR, GYANENDRA, SINGH, RANI, KUMAR, MAHESH, and SHARMA, ARJAVA
- Subjects
- *
AQUAPORINS , *SINGLE nucleotide polymorphisms , *BULLS , *DNA , *SEMEN , *ALLELES , *CATTLE - Abstract
The article focuses on a study which examines the link between the single nucleotide polymorphism located in bovine aquaporins gene with semen quality parameters including semen volume, concentration, motility, post-thaw motility, viability, and hypoosmotic swelling response of Frieswal bull semen. Information about the materials and methods used in the study is presented such as DNA samples and semen collection.
- Published
- 2015
- Full Text
- View/download PDF
46. Performance evaluation of self-breakdown-based single-gap plasma cathode electron gun.
- Author
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KUMAR, NIRAJ, PAREEK, NALINI, PAL, UDIT, VERMA, DEEPAK, PRAJAPATI, JITENDRA, KUMAR, MAHESH, MEENA, BHARAT, and PRAKASH, RAM
- Subjects
- *
ELECTRON gun , *ARGON , *ELECTRON beams , *GLOW discharges , *MAGNETIC fields , *PLASMA gases - Abstract
This paper presents the experimental studies on self-breakdown-based single-gap plasma cathode electron (PCE) gun (5-20 kV/50-160 A) in argon, gas atmosphere and its performance evaluation based on particle-in-cell (PIC) simulation code 'OOPIC-Pro'. The PCE-Gun works in conducting phase (low energy, high current) of pseudospark discharge. It produces intense electron beam, which can propagate more than 200 mm in the drift space region without external magnetic field. The profile of this beam in the drift space region at different breakdown conditions (i.e., gas pressures and applied voltages) has been studied and the experimental results are compared with simulated values. It is demonstrated that ∼30% beam current is lost during the propagation possibly due to space charge neutralization and collisions with neutral particles and walls. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
47. Nodulation of legumes from the Thar desert of India and molecular characterization of their rhizobia.
- Author
-
Gehlot, Hukam, Panwar, Dheeren, Tak, Nisha, Tak, Alkesh, Sankhla, Indu, Poonar, Neetu, Parihar, Rashmita, Shekhawat, Narpat, Kumar, Mahesh, Tiwari, Ravi, Ardley, Julie, James, Euan, and Sprent, Janet
- Subjects
- *
PROKARYOTES , *ANNUALS (Plants) , *RHIZOBIACEAE , *FUNGUS-bacterium relationships - Abstract
Aims: To survey the occurrence of nodulated legumes in the arid and semi-arid areas of Western Rajasthan and to characterize their associated symbiotic bacteria. Methods: Herbaceous annual species were excavated whole, while tree species were studied as seedlings in the field or as trap plants in pot experiments. Nodules were examined by microscopy to confirm their effectiveness and to determine their internal structure. Bacteria isolated from the nodules were authenticated on their original hosts and were identified on the basis of 16S rRNA sequencing. Phylogenetic trees were inferred using the neighbour-joining method. Results: We studied 35 of more than 50 species of native legume reported from these areas. Legumes are drought escaping (annual species), drought tolerant perennials or trees possessing deep root systems and other adaptations to arid conditions. Nodulation was recorded in all members of the Papilionoideae and Mimosoideae, but only one species of Caesalpinioideae. Internal structure of nodules varied within these groups, especially with respect to the presence or absence of uninfected cells in the infected region. Full 16S rRNA gene sequencing revealed that the nodules harboured a range of nodulating bacteria belonging to the genera Sinorhizobium, Rhizobium and Bradyrhizobium, within which they formed separate sub clades. Conclusions: This study extends the range of legumes known to grow and nodulate in semi-arid regions, and provides information about their endosymbionts. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
48. Role of surface modification of colloidal CdSe quantum dots on the properties of hybrid organic–inorganic nanocomposites.
- Author
-
Kumar, Umesh, Kumari, Kusum, Sharma, Shailesh N., Kumar, Mahesh, Vankar, V. D., Kakkar, Rita, and Kumar, Vikram
- Subjects
- *
PHOSPHINE , *QUANTUM dots , *POLYMERS , *SOLAR cells , *CHARGE transfer - Abstract
In this work, tri-octyl phosphine/tri-octyl phosphine oxide (TOPO)-capped cadmium selenide (CdSe) quantum dots (QDs) of varied sizes (5–9 nm), prepared by varying the input Cd:Se precursor ratio using chemical route, were dispersed in conducting polymer matrices viz. poly[2-methoxy, 5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and poly(3-hexylthiophene) (P3HT). By using a binary solvent mixture (pyridine–chloroform), homogeneous dispersion of CdSe nanocrystals in polymers (MEH-PPV, P3HT) could be realized. The properties of the resulting dispersions could be tailored by the composition and concentration of QDs in polymer. The emission and structural properties of polymer–CdSe nanocomposites are found to be dependent on the crystallite size and morphology of CdSe nanocrystallites. An effective quenching of photoluminescence emission in the polymer nanocomposite was observed for smaller CdSe quantum dots (size ∼6 nm) as compared to larger CdSe quantum dots (size ∼9 nm), thus ensuring efficient charge transfer process across the polymer–CdSe interface in the former case. The incomplete quenching, particularly for MEH-PPV:CdSe nanocomposites, could be as a result of insufficient coverage of polymers on the surface of CdSe nanocrystallites, mainly due to phase segregation for TOPO-stripped CdSe nanocrystallites. The superior morphology and optical properties of polymer nanocomposite (P3HT:CdSe QDs) could play a pivotal role for the realization of effective charge separation and transport in hybrid solar cells. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
49. Field assessment of an H5N1 inactivated vaccine in chickens and ducks in Lao PDR.
- Author
-
Boltz, David A., Douangngeun, Bounlom, Sinthasak, Settha, Phommachanh, Phouvong, Midouangchanh, Phetlamphone, Walker, David, Keating, Rachael, Khalenkov, Alexey M., Kumar, Mahesh, and Webster, Robert G.
- Subjects
- *
INFLUENZA vaccines , *VACCINATION , *BLOOD agglutination , *NEUTRALIZATION (Chemistry) - Abstract
Despite the extensive use of poultry vaccines to control the spread of H5N1 influenza in poultry, H5N1 outbreaks continue to occur in domestic birds. Our objective was to determine the duration of the neutralizing antibody response under field conditions after vaccination with a laboratory-tested inactivated reverse genetics-derived H5N3 vaccine. H5N3 hemagglutination inhibition (HI) and virus neutralization (VN) antibodies were observed 40 weeks after vaccination of chickens with two doses and vaccination of ducks with one dose. Cross-clade antibodies to an H5N1 virus (A/chicken/Laos/A0464/07) antigenically distinct from the vaccine strain were detected in ducks after a single vaccination and were sustained for 28 weeks (for 40 weeks when a boost vaccination was given). Our results indicate that this inactivated H5N3 vaccine can produce long-lasting antibodies to homologous and heterologous viruses under field conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
50. Room-Temperature Gas Sensors Under Photoactivation: From Metal Oxides to 2D Materials.
- Author
-
Kumar, Rahul, Liu, Xianghong, Zhang, Jun, and Kumar, Mahesh
- Subjects
- *
METALLIC oxides , *METAL oxide semiconductors , *PHOTOACTIVATION , *DETECTORS , *MATERIALS - Abstract
Highlights: Operations of metal oxide semiconductors gas sensors at room temperature under photoactivation are discussed. Emerging two-dimensional (2D) materials-based gas sensors under light illumination are summarized. The advantages and limitations of metal oxides and 2D-materials-based sensors in gas sensing at room temperature under photoactivation are highlighted. Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap, low power consumption and portable sensors for rapidly growing Internet of things applications. As an important approach, light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity, speed and selectivity. This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field. First, recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted. Later, excellent gas sensing performance of emerging two-dimensional materials-based sensors under light illumination is discussed in details with proposed gas sensing mechanism. Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics. Finally, the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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