Amarish Dubey

Nano iron pyrite (FeS2) exhibits bi-functional electrode character

Sustainable charge storage devices require materials that are environmentally benign, readily moldable, easily synthesizable, and profitable for applications in the electronics industry. Nano iron pyrite (FeS2) is one such material, which is applicable in diverse areas like photovoltaic devices to seed dressing in agriculture. In this work, we propose an innovative application of nano FeS2viz., as a symmetric charge storage device that is flexible, portable, and lightweight; along with its fabrication details. The device consists of a (H3PO4)/polyvinyl alcohol (PVA) electrolyte gel sandwiched between two similar electrodes made up of FeS2/poly-aniline (PA), upon which graphite sheets are used as current collectors. Electrodes were characterized by XRD, FTIR and SEM. The device was calibrated by cyclic voltammetry and charge–discharge cycle. In its present laboratory prototype form, it powers solid-state electronic devices and electric motors. Further refinements of this device will open up new avenues in the field of sustainable charge storage devices and low power electronics.

Soft magnetic memory of silk cocoon membrane.

Silk cocoon membrane (SCM), a solid matrix of protein fiber, responds to light, heat and moisture and converts these energies to electrical signals. Essentially it exhibits photo-electric and thermo-electric properties; making it a natural electro-magnetic sensor, which may influence the pupal development. This raises the question: ‘is it only electricity?’, or ‘it also posses some kind of magnetic memory?’ This work attempted to explore the magnetic memory of SCM and confirm its soft magnetism. Fe, Co, Ni, Mn, Gd were found in SCM, in traces, through energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS). Presence of iron was ascertained by electron paramagnetic resonance (EPR). In addition, EPR-spectra showed the presence of a stable pool of carbon-centric free radical in the cocoon structure. Carbon-centric free radicals behaves as a soft magnet inherently. Magnetic-Hysteresis (M-H) of SCM confirmed its soft magnetism. It can be concluded that the soft bio-magnetic feature of SCM is due to the entrapment of ferromagnetic elements in a stable pool of carbon centric radicals occurring on the super-coiled protein structure. Natural soft magnets like SCM provide us with models for developing eco-friendly, protein-based biological soft magnets.

The seed stimulant effect of nano iron pyrite is compromised by nano cerium oxide: regulation by the trace ionic species generated in the aqueous suspension of iron pyrite

A brief seed pretreatment of 12 hours, in an aqueous suspension of synthesized nano iron pyrite (FeS2), significantly increases the yield of spinach and other crops. The effector mechanism is not clear. An aqueous suspension of FeS2, produces very trace amounts of H2O2, Fe2O3, FeS, FeSO4, Fe(SO4)3, SO2, S and H+ ionic species. Thus for 12 hours, seeds are exposed to this complex aqueous suspension. Among these trace species, H2O2 and Fe2O3 are known seed stimulants and plant growth promoters respectively. In this work, an attempt has been made to quench one of these trace compounds generated in the aqueous suspension of FeS2, viz., H2O2; and the long-term effect on the mature plant was monitored. To test this, along with FeS2, an agriculturally relevant inorganic peroxide scavenger viz., nano cerium oxide (CeO2) was introduced into this system. Four seed pretreatment regimens were followed for the spinach viz., (i) control (water), (ii) FeS2 + water, (iii) CeO2 + water, (iv) FeS2 + CeO2 + water; and growth was monitored for the next 80 days. It was found that, at maturity, CeO2 and FeS2 + CeO2, resulted in significantly smaller leaves, as compared to the control and FeS2; furthermore, FeS2 resulted in leaves with increased chlorophyll and carbohydrate. Thus, the data indicates that by quenching the H2O2, the seed-stimulant effect of FeS2 is compromised. So, while the FeS2 + water suspension functions as a seed vigor enhancer, CeO2 + water on the contrary, functions as a ‘seed vigor reducer’. It is noteworthy, that CeO2 is used by Chinese farmers, as a micro-nutrient to increase crop production. Current data indicates that, it delays germination of seeds, whereas FeS2 hastens germination. Thus such an approach could be used for hastening or delaying germination, manipulating weed population, seed storage in critical conditions, timing the life-cycle of a plant and developing more energy-efficient plants, especially in regions, where there is limited sunlight during significant parts of the year.

Nano-iron pyrite seed dressing: a sustainable intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops

AbstractContinuous agricultural innovations are required to feed the exploding human population through natural or artificial resources. Though light is ample on earth, two-third of unavailable ocean and one-third of available soil are major limiting factors to free growth. Excessive fertilizer usage is irreversibly altering the chemical ecology of soil, further reducing the available area. Seed metabolism might be a potential answer to this resource crunch. Without genetic modification and thus maintaining the existing biodiversity, manipulation of seed metabolism at the very onset of germination is a sustainable alternative. The current work presents seed priming with iron pyrite (FeS2) prior to sowing as one such sustainable and innovative intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops. A 12-h seed pretreatment in an aqueous suspension of nano-iron disulfide/pyrite (FeS2) resulted in significant yield increase in the above crops. While agriculturists aim to restore the natural genomic diversity of different domesticated crops, environmental engineers require technologies to reduce fertilizer consumption without compromising agricultural yields, thereby making the planet more sustainable. This nanoscale seed pretreatment approach using FeS2, otherwise a benign earth abundant mineral, suggests the sustainable opportunity to translate this technology to other crops thereby enhancing the global agricultural production.

Water mediated dielectric polarizability and electron charge transport properties of high resistance natural fibers

Recent studies showed that silk and human hair fibers develop thermoelectric properties at optimal water, temperature and light conditions. The nature of charge carriers and the role of water in mediating charge conduction in these fibers is an unexplored issue. By studying four different classes of natural fibers, viz., silk cocoon, human hair, jute and corn silk, we uncover their common electrical transport properties and its dependence on water concentration and temperature. All these fibers uniformly exhibit nonlinear, hysteretic current - voltage characteristics, which scale with water concentration. The optimal electrical conductivity shows thermally activated hopping transport mechanism. Scanning tunneling microscope (STM) and dielectric measurements of silk cocoon fibers showed the electronic density of states and dielectric properties of the hydrated medium enhances with water concentration. Electron paramagnetic resonance (EPR) study reveals that the charge carriers in these membranes are electronic in nature. Our results are explained through the mechanism of hopping of a Polaron, which is an electron surrounded by positive charge fluctuations created by water molecules. The mechanism unravels the peculiar role water plays in mediating electrical activity in these membranes and also opens the possibility for exploring such charge transport mechanism in other biological membranes.

Biocharring of natural fibers of insect and plant origin: a green route for the production of ‘carbon-based charge storage nanomaterials’

Futuristic energy materials are expected to be biocompatible, green, sustainable and economical. One of the ways to develop such energy storage materials is by utilizing natural sources such as plants, animals, and insects. Autotrophs fix nitrogen and carbon in the atmosphere through rhizobium and photosynthesis, respectively, which are later consumed by animals and insects as energy sources. Biocharring these plants and insects derived products that could help us regain this carbon and nitrogen in the form of biocharred energy materials. Insect-derived Tassar cocoon, Mulberry cocoon, and Tassar silk thread give N-doped carbon matrix upon biocharring which is further processed to obtain reduced graphene oxide, whereas plant-derived Jute gives a pure carbon matrix on biocharring, all four materials show typical properties of charge storage. Exploring further on these natural charge storage materials will help the energy industries to design green charge storage systems. Further, such an approach in future will open up new avenues of business for silk and jute farmers of the world.

Cellulosic fibers from Lotus (Nelumbo nucifera) peduncle

ABSTRACT Lotus (Nelumbo nucifera), an aquatic monocotyledonous plant, is highly valued for cut flower and plant parts containing medicinal properties. The paper presents the method of drawing out cellulosic fibers from lotus peduncles. Mechanical properties of lotus fibers were evaluated and compared with other common natural fibers. Morphology and characteristics of lotus fiber and peduncle were studied using scanning electron micrograph. Fiber characterization was done to identify the elements present and chemical composition in the lotus fiber by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Results reveal that lotus fiber is one of the finest (0.22 tex) natural fibers with helical structure and promising quality. Chemical characterization of the lotus fiber shows presence of cellulose and similarity with cotton fibers.

A Sustainable, Eco-friendly Charge Storage Device from Bio-charred Jute: An Innovative Strategy to Empower the Jute Farmers of India

Jute is a major fiber crop of India, which is used extensively as packaging material. Recently, jute industry is facing stiff challenges from synthetic fibers and plastics; resulting in major decline in the revenue of jute growers. This necessitates the quest for alternative and innovative design avenues where jute can be used to fulfill the need of the jute growers. This paper describes one such alternative where a sustainable, eco-friendly charge storage device is developed using bio-charred jute; thereby opening new avenues for jute industry in the energy storage sector. Implementing similar innovative strategies at national level could revive the interest in jute farming among Indian jute growers and other cash crop growers.