Browsing by Author "Vimal Singh"

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Automatic Voltage Regulation of DC Shunt Generators
(1973) Vimal Singh; S.K. Kak; Srinivasan Rangarajan
In a dc shunt generator, as the load increases the terminal voltage falls, giving a drooping characteristic. The regulation of voltage involves the adjustment of field excitation. A simple method of voltage regulation by automatic adjustment of field excitation making use of transistor circuitry is discussed. The added advantage of this method is that by the simple adjustment of circuit parameters, the characteristics of a compound generator can be achieved. Experimental results prove the effectiveness of the method. Copyright © 1973 by The Institute of Electrical and Electronics Engineers, Inc.
Diversity of Azotobacter and Azospirillum in rhizosphere of different crop rotations in eastern Uttar Pradesh of India
(2012) B.R. Maurya; Ashok Kumar; Richa Raghuwanshi; Vimal Singh
Azotobacter and Azospirillum are known as non symbiotic free living nitrogen fixing biofertilizer microorganisms which actively participate in nutrients cycles. In eastern Uttar Pradesh of India, there is a great diversity in various cropping systems that may possess variation in these important biofertilizer microorganisms. The present study was conducted in order to chalk out the diversity of Azotobacter and Azospirillum sp. in different districts of eastern Uttar Pradesh in India with respect to the prevailing cropping system. Sixty two soil samples were collected from different crop rotations namely rice-wheat, vegetables, agroforestry and grassland for enumerating the diversity of Azotobacter and Azospirillum. The result showed that the Azotobacter population in rice-wheat, vegetables, agroforestry and grassland based crop rotations varied from 10×105 -13×105, 12×105-16.5×105, 9×105-15.5×105 and 7×105-10.5×105 CFU g-1 soil, respectively. Population of Azospirillum in rice-wheat, vegetables, agroforestry and grassland based crop rotations varied from 5.5×105-10.5×105, 6.5×105-12×105, 5×105-13×105 and 4.5×105-10×105 CFU g-1 soil, respectively. The diversity in population density of Azotobacter was maximum in soil of agroforestry followed by vegetables, grassland and lowest in rice-wheat based crop rotations, while in case of Azospirillum diversity was maximum in agroforestry and the lowest was observed in the rice-wheat but similar diversity present in vegetables and grassland crop rotations soil of eastern Uttar Pradesh. Overall maximum diversity of both the biofertilizer micro-organisms occurred in agroforestry based crop rotation. © 2012 Academic Journals Inc.
Effect of copper sulphate on seed germination, plant growth and peroxidase activity of mung bean {vigna radiata)
(2011) Jay Prakash Verma; Vimal Singh; Janardan yadav
The aim of this study was to find the effect of copper as a micronutrient for enhanced plant growth, protein content and antioxidant enzyme activity of mungbean (Vigna radiata) under the influence of different concentrations of copper. The effect of various copper sulphate solution has insignificant effect on the percent germination of mungbean while plumule and radicle length decreased with increase in copper concentration (50, 200, 500 and 1000 μM copper sulphate solution). Total protein content in root was significantly higher (127.7%) than shoot (83.7%) as compared to control. Peroxidase activity, in case of shoot, increases with increase in copper sulphate concentration i.e., (1.423 of control to 1.713, 2.29, 2.52, 2.88 and 3.02 OD/min/mg protein in different copper sulphate solutions treatments after 72 h) while for the root copper sulphate solution has negative effect on the peroxidase activity i.e., (11.41 of control to 11.19, 10.85, 10.04, 9.73 and 9.40 OD/min/mg protein in different copper sulphate solutions treatments after 72 h). The present experiment revealed that copper is an essential micronutrient which promoted the seedlings growth at less than 50 μM concentration. Higher concentration significantly decreases shoot and root length. The protein concentration in both shoot and root of the seedling was recorded to be enhanced with increase in the concentration of copper sulphate as compared to control. POD activity in root decreased at higher levels of copper concentration while POD activity in shoot increased with increasing concentration. © 2011 Asian Network for Scientific Information.
Enhanced Osteogenesis by Molybdenum Disulfide Nanosheet Reinforced Hydroxyapatite Nanocomposite Scaffolds
(American Chemical Society, 2019) Umakant Yadav; Himanshu Mishra; Vimal Singh; Sunayana Kashyap; Anchal Srivastava; Sanjay Yadav; Preeti S. Saxena
The advances in the arena of biomedical engineering enable us to fabricate novel biomaterials that provide a suitable platform for rapid bone regeneration. Herein, we have investigated the in vitro and in vivo osteogenic differentiation, proliferation, and bone regeneration capability of molybdenum disulfide nanosheets (MoS2NSs) reinforced HAP nanocomposite scaffolds. The MG-63 cells were incubated with HAP and HAP/MoS2NSs nanocomposite and followed for various cellular activities. The cells incubated with HAP@2 shows higher cell adhesion, cell proliferation, and alkaline phosphatase activity (ALP) in contrast to HAP. The in vivo and in vitro results of the increased ALP level confirm that HAP@2 promotes osteogenic differentiation. This improved osteogenesis was validated with upregulation of osteogenic marker viz. transcription factor, RUNX-2 (∼34 fold), collagen-1 (∼15 fold), osteopontin (∼11 fold), osteocalcin (∼20 fold), and bone morphogenetic protein-2 (∼12 fold) after 12 week postimplantation in comparison to drilled. The X-ray imaging demonstrates that HAP@2 implants promote rapid osteogenesis and bioresorbability than HAP and drilled. The outcomes of the present study provide a promising tool for the regeneration of bone deformities, without using any external growth factor. © 2019 American Chemical Society.
Enzymatic activities and microbial population in agric-soils of Almora district of central Himalaya as influenced by altitudes
(2011) B.R. Maurya; Vimal Singh; P.P. Dhyani
Abundance of various kind of microorganisms and their activity in soil is a presumptive of fertility status of that soil. Hence, the present study was designed to assess the impact of altitudes on activity of two important soil health bioindicators in agricultural soils of Almora district of Central Himalaya. Seventy two soil samples were collected from agricultural lands at different altitudes of Almora, Uttarakhand, India and were assayed for their electro-chemical properties microbial colony forming unit (cfu) and microbial activities such as dehydrogenase and phosphatase following the standard procedures. It was recorded that soil was acidic in range with nitrogen, phosphorous and potassium in middle to high range. Also their content in soil increased at high altitude as compared to low altitude. Dehydrogenase and phosphatase activities varied with altitudes and these were high at higher altitudes. Dehydrogenase possessed a significant and positive correlation with nitrogen (r=0.83) and phosphorous (r = 0.64) while phosphatase showed significant and positive correlation with organic carbon (r=0.66). It was concluded that activity of dehydrogenase and phosphatase in soil would be an effective tool to assess the soil health. © 2011 Academic Journals Inc.
Facile, rapid and upscaled synthesis of green luminescent functional graphene quantum dots for bioimaging
(Royal Society of Chemistry, 2014) Vinod Kumar; Vimal Singh; Sima Umrao; Vyom Parashar; Shiju Abraham; Anand K. Singh; Gopal Nath; Preeti S. Saxena; Anchal Srivastava
We report here the upscaled synthesis of green luminescent functionalized graphene quantum dots (FGQDs) by using an inexpensive and commonly occurring natural precursor viz. graphite powder. We observed in our sample that photoluminescence increases for excitation wavelengths of 300 nm to 350 nm and then decreases when excited at 375 to 425 nm for FGQDs at neutral pH. We found that the synthesized FGQDs do not show a drastic change in emission properties when kept under different pH conditions, which makes them a potential candidate for in vivo imaging, where the pH of the culture media plays a crucial role in the maintenance of the fluorescence. Water solubility, and excellent photostability along with low cytotoxicity of FGQDs are manifested as a remarkable bioimaging material. This journal is © the Partner Organisations 2014.
Graphene Oxide Synergistically Enhances Antibiotic Efficacy in Vancomycin-Resistant Staphylococcus aureus
(American Chemical Society, 2019) Vimal Singh; Vinod Kumar; Sunayana Kashyap; Ajay Vikram Singh; Vimal Kishore; Metin Sitti; Preeti S. Saxena; Anchal Srivastava
The current study highlights a new polyvalent inhibitor approach based on Vancomycin conjugated with graphene oxide (Van@GO) against a Vancomycin-resistant Staphylococcus aureus (VRSA) strain. Physicochemical characteristics of the prepared Van@GO composites were studied using UV-vis and FTIR spectroscopy techniques. Characterization results confirm the attachment of Vancomycin to the graphene oxide. A significant inhibition of VRSA growth is achieved by Vancomycin when presented as Van@GO. The polyvalent inhibition activity of Van@GO was characterized by performing bacteriological experiments along with scanning electron microscopy. Results clearly exhibit the enhanced inhibition activity of Van@GO compared to Vancomycin alone against VRSA. The high surface area of GO facilitates high loading and multivalent interaction of conjugated Vancomycin leading to polyvalent inhibition. Further, we found that Van@GO significantly reduces the motility of VRSA via inducing oxidative stress compared with untreated samples. Our findings highlight the importance of Van@GO as an effective polyvalent inhibition recipe for VRSA. © 2019 American Chemical Society.
Natural gamma-ray spectrometry as a rapid sensing method for detecting variations in soil shrinking and cracking behaviour: An application case study
(Elsevier Ltd, 2023) Argha Basu; Varun Narayan Mishra; Nirmal De; Vimal Singh
Soils which develop desiccation cracks after drying are unsuitable for the making of earthenware. The present work was carried out to demonstrate the use of Natural Gamma-ray Spectrometry (NGS) as a rapid sensing method to detect the variation of cracking behaviour and types of clay dominant in soil using samples collected from the study region. Natural gamma-ray intensities due to potassium (K) and equivalent thorium (eTh) radioisotopes present in soil were recorded using an NGS device. Circular soil cakes of set diameter were sun-dried to find shrinking and cracking variations. Other tests included measurement of particle size distribution, Atterberg indices, basic soil physico-chemical properties, exchangeable cation contents using ICP-OES and XRD identification of clays. 6 soil varieties were identified from the distribution of data points in the binary plots of gamma-ray potassium (GR-K) and thorium (GR-eTh) counts per sec (C/s). Variation of GR-K was observed to be wider (2.14 C/s to 2.54 C/s) than GR-eTh (0.44 C/s to 0.63 C/s). The measured GR-K counts reflect changes in illite content. The soils displayed 3 categories of shrinking and cracking behaviour. The soil variety which displayed maximum mild shrinkage without fine desiccation cracks on the set surface area has the highest GR-K counts. The soil shrinking and cracking variations were not clearly defined by the classification based on the texture and plasticity chart, though the latter indicated dominant smectites. A strong linear relationship between GR-K and exchangeable K (R2 = 0.84) indicates K+ contribution mainly from illite and dominance of other clay types in outliers. Higher levels of polyvalent cations known for binding clay aggregates were observed in the non-cracking soils. Concomitant higher GR-K levels indicate that shrinking soils lacking fine desiccation cracks are associated with fluvial sediments of the recent past with parental mica. This research concludes that NGS-based portable devices can be used for rapid sensing of soils to detect variation in shrinking and cracking behaviour and dominant clay type and thus can be used for identification of soil suitable for earthenware making. © 2023 Elsevier Ltd
Nitrogen doped carbon quantum dots demonstrate no toxicity under: In vitro conditions in a cervical cell line and in vivo in Swiss albino mice
(Royal Society of Chemistry, 2019) Vimal Singh; Sunayana Kashyap; Umakant Yadav; Anchal Srivastava; Ajay Vikram Singh; Rajesh Kumar Singh; Santosh Kumar Singh; Preeti S. Saxena
Carbon quantum dots (CQDs) and their derivatives have potential applications in the field of biomedical imaging. Toxicity is one of the critical parameters that can hamper their success in biological applications. In this context, our goal was to systematically investigate both in vivo and in vitro toxicity of nitrogen doped carbon quantum dots (NCQDs). In vivo toxic effects were evaluated for 30 days in Swiss albino mice at two different concentrations (5.0 mg per kg body weight (BW) and 10.0 mg per kg BW) of NCQDs. Results of haematological, serum biochemical, antioxidant and histopathological parameters showed no noteworthy defects at both of these concentrations. An in vitro assessment was performed against the human cervical cancer cell line (HeLa cells) at the concentration of 0-400 μg ml-1. The LDH profile, DNA fragmentation, apoptosis, and growth cycle of cells showed no apparent toxicity of NCQDs. The overall study offers highly biocompatible N-doped carbon quantum dots, which may be considered as an attractive material for future biomedical applications. © 2019 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
QPRTase modified N-doped carbon quantum dots: A fluorescent bioprobe for selective detection of neurotoxin quinolinic acid in human serum
(Elsevier Ltd, 2018) Ranjana Singh; Sunayana Kashayap; Vimal Singh; Arvind M. Kayastha; Hirdyesh Mishra; Preeti Suman Saxena; Anchal Srivastava; Ranjan K. Singh
Highly fluorescent nitrogen doped carbon quantum dots (NCQDs) were synthesized using microwave assisted green method. It was characterized by Transmission Electron Microscopy (TEM), FTIR, UV–Visible absorption and Photoluminiscence (PL) techniques. The NCQDs were immobilized with an enzyme named quinolinate phoshphoribosyl transferase (QPRTase). The NCQDs immobilized by QPRTase was used as a fluorescent bioprobe for the selective detection of endogenous neurotoxin quinolinic acid (QA) whose elevated level in serum is marker of many neurological disorders such as Alzheimer's, Huntington's and HIV associated dementia (HAD) as well as deficiency of vitamin B6. Steady state PL studies were carried out to measure the PL response of the fabricated fluorescent bioprobe as a function of QA concentrations in human serum samples. This probe was found applicable in linear range [3.22–51 µM] with the limit of detection ~ 6.51 µM. It has desirable sensitivity ~ (0.02340±0.0001) µM−1, excellent stability for ~ 7 weeks and good reproducibility. The similar response of this fluorescent bioprobe for QA detection in triple distilled water and human serum shows that it is unaffected by variation in media. Hence, this fluorescent bioprobe can be employed for QA detection in serum sample for the early detection of many diseases. © 2017
Speed and voltage regulation of d.c. shunt machines using power transistor in field circuit
(1974) Vimal Singh; S.K. Kak
A simple method for speed and voltage regulation of d.c. shunt machines is presented. The method is based on the use of a power transistor circuit which automatically adjusts the field current Such that the Speed or output voltage, as the case may be, is maintained constant with increasing load on the machine. An added advantage of this inothod is that, by the simple adjustment of circuit parameters, the characteristics of a compound generator can be achieved from a shunt generator without using a series field winding. Experimental results prove the effectiveness of the method. © 1974 Taylor & Francis Ltd.
Sustainable extraction and conservation of soil resources: New insights through Natural Gamma-ray Spectrometry based Proximal Sensing Method
(Elsevier Ltd, 2024) Argha Basu; Varun Narayan Mishra; Nirmal De; Vimal Singh
Soil is one the most extracted natural raw materials. The vast expanses of fertile alluvial soils of the Indo Gangetic Plains have long remained as abundant soil resource pool for brick manufacturing and construction sectors. Unmonitored continuous removal of soil is reported to cause depletion of soil reserves, loss of soil fertility and affect crop yield. Excavation and removal of soil from isolated patches of land creates low lying and elevated degraded areas which disrupts normal crop cultivation pattern. Natural gamma-ray spectrometry (NGS) can be used as a non-destructive and rapid geophysical sensing method, for identification and delineation of areas with suitable soils. During this work brick kiln areas were visited to understand soil's availability and extraction pattern. NGS measurements of samples from soil profiles were carried out to find if gamma-ray intensities varied with soil clay content. Soil texture and plasticity of the same samples were obtained following standard testing procedures. Winkler and Plasticity charts were used to assess suitability of the soils. A strong linear relationship between gamma-ray potassium (K) intensity and clay contents of soil profile samples (R2 = 0.88) was observed. NGS based devices can be used to scan soil samples rapidly and log shallow depth boreholes in grid sampling design. The gathered spectral gamma-ray data can be then used to predict and generate high resolution 3D models of soil properties, based on which resource areas of suitable soils can be delineated for long term soil extraction without affecting cultivated areas. This will help in delineating areas restricted for soil extraction, which will not only make soil mining sustainable but also address soil conservation by setting aside large cultivated fertile soil areas untouched. Adopting NGS methods will prevent unsystematic removal of fertile soil and creation of degraded lands. This will ultimately result in efficient soil resource management. © 2024 Elsevier Ltd