Browsing by Author "Ajay Kumar Singh"

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Biochar's multifaceted role in bioremediation of emerging contaminants and heavy metals in complex rhizospheric ecosystem
(Elsevier Ltd, 2025) Shiv Vendra Singh; Shivangi Raghuvanshi; Yogeshwar V. Singh; Krishna Kumar Yadav; Amel Gacem; Tony Manoj K. Nandipamu; Mohammad Khalid; Rashida Hameed; Rashmi Sharma; Debarati Datta; Saurabh Ghosh; Arpna Kumari; Ajay Kumar Singh; Biswajit Pramanick; Xiuxiu Zhang; Chongqing Wang; Maha Awjan Awjan Alreshidi
Rising prevalence of emerging contaminants (ECs) and priority heavy metals (PHMs) poses grave threats to the health of the environment and humankind, majorly resulting from human activity such as mining, disposal of industrial wastes, and use of chemicals. These pollutants drastically reduce soil biodiversity, fertility, and crop yield, rendering agricultural goods hazardous. Biochar has recently received attention as a sustainable bioremediation solution for ECs and PHMs through diverse physical, chemical, and biological processes. Biochar has demonstrated significant bioremediation efficiency for PAHs, antibiotics, microplastics, and pesticides varied from 50 to 95% and 60–90% for PHMs in a wide range of ecosystems. The interactive mechanisms of complexation, precipitation, ion exchange, surface sorption, and electrostatic interaction, hydrophobic interaction electron donor and acceptor interaction altogether enhance contaminant immobilization and biodegradation. Furthermore, biochar has been shown to aid in the breakdown of contaminants while lowering the transportation and accessibility of heavy metals. Besides remediation, biochar improves the rhizospheric environment by enhancing plant growth, nutrient uptake, and soil vitality. Its ability to remove both heavy metals and organic pollutants from wastewater and soil matrices, and its influence on their bioavailability and transport, show the dual nature of biochar in restoring environments. This manuscript attempts to provide in-depth insight into the challenges that ECs and PHMs pose, the role of biochar in their removal, and delicate soil-plant-biochar interactions. The work here discusses these interacting effects, thus giving insight into the potential of biochar in the immobilization of ECs and PHMs through many interspecific reactions, and also the soil-plant-biochar interactions and possibilities for successful remediation. © 2025 Elsevier Ltd
Curious structural characteristics from the carbon deposits on the graphitic electrodes subjected to arc evaporation
(Japan Society of Applied Physics, 1997) Radha Kamalakaran; Ajay Kumar Singh; Onkar Nath Srivastava
We report the transmission electron microscopic investigations made on the tips of the graphite electrodes used for production of C60-buckminsterfullerene. This was achieved by triggering an electrical arc (150 A, 20V, ac) in helium (100 Torr) atmosphere between the graphite electrodes and then scraping the tip of the electrode to prepare sample for electron microscopy. The scraped material was investigated in the CM-12 Philips transmission electron microscope both in diffraction and imaging modes. An abundance of tubules were found and the diffraction patterns from them exhibited sharp diffraction spots arranged along elliptical rings. On tilting the specimen the major axis of the ellipse varied in definite was depending on the relative orientations of electron beam, tubule axis and tilt axis. A detailed geometrical exemplification has been proposed which explains the observed features in the diffraction patterns. The occurrence of possibly a new form of carbon corresponding to primitive cubic with a = 2.14 Å and nucleation of diamond on ac electrical arc treated graphite electrode are also mentioned.
Effect of integrated nutrient management on physico-chemical properties of soil, growth, yield and quality of rice under irrigated ecosystem of Uttar Pradesh
(Ecological Society of India, 2014) M. Hasan; D.K. Singh; Amitesh Kumar Singh; Ajay Kumar Singh
Higher organic carbon, electrical conductivity, bulk density and growth attributes viz. plant height, tillerand dry matter were recorded in 50 % N through carpet waste + 50% N through urea + PSB + 20 kg S ha-1 and this treatment was significantly higher over all other treatments but which was at par with 50 % N through FYM + 50% N through urea + PSB + 20 kg S ha-1 at all stages of crop. Higher pH was recorded at 50 % N through carpet waste + 50% N through urea + PSB + 20 kg S ha-1 and minimum pH was recorded at control treatment. Maximum grain and straw yield were recorded (4.6 and 6.41 ha-1) with 50 % N through carpet waste + 50% N through urea + PSB + 20 kg S ha-1 and which was significantly superior to all others treatment. Nutrient uptake and nutrient available in soil were found in 50 % N through carpet waste + 50% N through urea + PSB + 20 kg S ha-1 and this treatment was significantly to all others treatment but which was at par with 50 % N through FYM + 50% N through urea + PSB + 20 kg S ha-1 at all stages of crop.
Exogenous gibberellic acid does not induce early flowering in mungbeans [vigna radiata (L.) Wilczek.]
(Agricultural Research Communication Centre, 2020) Susheel Kumar Raina; Punam Singh Yadav; Ajay Kumar Singh; Nikhil Raskar; Jagadish Rane; Paramjit Singh Minhas
Gibberellic acid (GA) is an important phyto-hormone mediating plant growth. In present study, we evaluated the impact of GA treatment on morphological, phenological and molecular aspects of five mungbean genotypes. GA treatment caused a significant increase in plant height and branch angle in most of the genotypes. However, there was no impact of GA treatment on days to first anthesis, days to 50% flowering and pod length. Genotypes SML-859 and EC-48 revealed no change in their plant height and branch angle respectively upon GA treatment, suggestive of their probable GA insensitivity. Expression of flowering associated gene-VrSOC1 remained unaffected by GA treatment, validating thereby that exogenously supplied GA does not induce early flowering in mungbeans. © 2020, Agricultural Research Communication Centre. All rights reserved.
High resolution electron microscopic studies of HoAl3, Er0·5Gd0·5Al3 and Y0·91Er0·09Al3 in thin film form
(Springer India, 1984) Anand Kumar Singh; Ajay Kumar Singh; M.S. Gupta; O.N. Srivastava
Rare earth trialuminides (RAl3) exhibit an interesting series of structures changing from 2H to 3C in the bulk form. Many of the rare earth trialuminides have been recently found to exhibit curious structural characteristics such as the occurrence of the modulated phases. A detailed investigation of the formation synthesis and characterization of some binary and ternary alloys of the rare earth-aluminium system has been carried out. High resolution microscopic technique has been employed to study the modulated phases for some alloys e.g. HoAl3, Er0·5Gd0·5Al3 and Y0·91Er0·09Al3. With the help of lattice imaging technique, several new modulated phases have been investigated. A possible mechanism for the formation of these phases has been suggested. The details of the results obtained by lattice imaging technique are discussed. © 1984 Indian Academy of Sciences.
Metal Organic Frameworks Based Nanomaterial: Synthesis and Applications; Removal of Heavy Metal Ions from Waste Water
(Springer Nature, 2022) Ravindra Singh; Rama Kanwar Khangarot; Ajay Kumar Singh; Kamlesh Kumar
Heavy metals in the water are a global environmental issue. Heavy metals in the wastewater are increasing day by day which is mainly caused by various industrial effluents. Heavy metal ions including, Cadmium (II), Arsenic (III and V), Chromium (III and VI), Copper (II), Lead (II), and Mercury (II) are accumulated readily in the environment. It has been created a lot of serious problem to the human health. Thus, removal of heavy metals from the wastewater is one of the major challenges for the scientific community. Various techniques and materials have been developed for removal of heavy metals from the waste water. Recently, Metal organic frameworks (MOFs) based nanomaterial has been synthesized and used for removal of heavy metal ions from waste water. Electrochemical, photochemical energy conversion and storage, biomedical imaging, drug delivery and catalysis, have been investigated. Its unique characteristic properties are accountable for the waste water treatment like easily synthesizable, various size cavities with different-different functional group, surface functional groups, various functionality where host–guest interaction takes place and high surface area which responsible for high absorption capacity. In this chapter, the attention is given to understand the synthesis, chemistry of MOF based nano-composites and its various applications especially, and removal of heavy metals from waste water has been discussed. It is expected that this chapter can be helpful to understand the synthesis of MOF-based nano-materials and its application towards the elimination of heavy metal ions from waste water. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
On the occurrence of modulated phases in binary and ternary rare earth metal trialuminides
(1983) Ajay Kumar Singh; Anand Kumar Singh; O.N. Srivastava
The investigations made on the synthesis and structural characterization of rare earth metal binary and ternary trialuminides are reported. These alloys were made by suitable homogenization using solid state interdiffusion and were tested by X-ray diffraction. Thin films from the initial agglomerate of the alloys were made by thermal vapour deposition in vacuum. These thin films were studied using transmission electron microscopy. High resolution transmission electron microscopy was also employed for the detailed structural characterization. The as-grown thin films were found to be amorphous. When the films were annealed, they underwent an amorphous-to-crystalline transformation accompanied by the formation of modulated phases. © 1983.
On the occurrence of polytypism in gadolinium aluminide thin films
(1979) Ajay Kumar Singh; O.N. Srivastava
[No abstract available]
On the structural characterization of the rare-earth-metal-based alloys ReAl3, Re1-xRe′xAl3, ReNi5, ReNi5-xAlx and ReNixAl3-x
(1982) Ajay Kumar Singh; Anand Kumar Singh; O.N. Srivastava
Crystallographic characteristics are known to influence the hydrogen absorption (desorption) and storage characteristics of intermetallic alloys. The disordered and amorphous phases are of particular importance. There is evidence that these phases absorb significantly more hydrogen than their crystalline counterparts. The growth, synthesis and structural characterization of the rare-earth-metal-based alloys ReAl3, Re1-xRe′xAl3, ReNi5, ReNi5-xAlx and ReNixAl3-x (Re, Re′ rare earth) were investigated using both bulk and thin film samples. Extensive structural characterization revealed that the as-grown thin film phases are amorphous. The transformation from the amorphous to the crystalline phase leads to the formation of several modulated phases. The importance of the results in regard to the hydrogen storage characteristics is outlined. © 1982.
On the synthesis of the Mg2Ni alloy by mechanical alloying
(1995) Arvind Kumar Singh; Ajay Kumar Singh; O.N. Srivastava
The synthesis of the hydrogen-storage alloy Mg2Ni has been carried out through a single-step mechanical alloying employing an energy ball mill. The synthesized ball-milled Mg2Ni alloy has been found to exist in the form of fine (nano) particles with sizes of about 40 Å. The nanoparticle form has been found to lead to easy activation for hydrogenation by annealing at 300 °C (about 10-4 Torr vacuum) for 30 min and hydrogen uptake has been found to commence from the first cycle itself. © 1995.
Preventing Microplastic Pollution in Surface Waters: Legal Frameworks and Strategic Actions
(John Wiley and Sons Inc, 2025) Monika Mahajan; Ajay Kumar Singh; Rajeev Pratap Singh; Pankaj Kumar Gupta; Sonu Singh; Mayank Pratap
Microplastic contamination of surface water is another looming environmental issue driven by fast industrialization, urbanization, and the rampant use of plastics. Microplastics are plastic particles smaller than 5 mm in size, and there are a variety of origins, including broken pieces of plastic waste, synthetic fibers, or industrial effluents. They are one of the pollutants that pose significant threats to aquatic ecosystems and human well-being because they carry toxic substances, disrupt aquatic food webs, and degrade water quality. This situation led India to formulate a series of regulatory frameworks for the reduction of plastic pollution. Other important policies are the 2016 Plastic Waste Management Rules, with a focus on recyclability and reduction of plastic waste at the source level, and the 2022 countrywide single-use plastic ban, which targets the spread of high-volume plastics that lead to microplastic pollution. India also works with international groups like the Global Partnership on Marine Litter and has integrated EPR into its plastic waste management to make it more long-lasting. In some states, incomplete or nonexistent waste management infrastructure and a lack of specific legislation on microplastics combine to raise concerns about enforcement. This review discusses the source and implications of microplastic contamination in the surface water, evaluates the effectiveness of the current legal regime, and highlights what could be done to strengthen the legislation and reduce microplastic contamination. Strengthened surveillance, state-of-the-art wastewater treatment technology, and awareness programs are essential before such elements can prevent the entry of microplastic contaminants and protect water bodies. © 2025 Wiley Periodicals LLC.
Spontaneous Common Bile Duct Perforation Presenting as Acute Abdomen
(Springer, 2010) Rahul Khanna; Nikhil Agarwal; Ajay Kumar Singh; Seema Khanna; Som Prakas Basu
Spontaneous common bile duct (CBD) perforation is an unusual cause of acute abdomen. It is rarely suspected or correctly diagnosed preoperatively. Clinical presentation is as biliary peritonitis. The common causes are CBD calculus disease, tumors of the bile duct, choledochal cyst and sometimes idiopathic. Treatment is surgical and consists of CBD exploration and repair over a T tube. © 2010 Association of Surgeons of India.