Deepu Philip

Seed treatment with iron pyrite (FeS2) nanoparticles increases the production of spinach

Certain nano-materials are known to have plant growth promoting effects, which could find applications in agriculture. We drew inspiration from the nano-factories of deep-sea hydrothermal vents; where iron pyrite nanoparticles serve as fertilizer to sustain chemoautotrophic life forms. We synthesized such iron pyrite nanoparticles in a controlled environment and used them as seed treatment agent (Pro-fertilizer). For us, the term ‘pro-fertilizers’ represents those materials that cause enhanced plant growth with minimum interference to the soil ecosystem when used for seed treatment. We conducted multi-location field trials on spinach crops, since it is a globally popular crop, consumed as both fresh (salads) and processed food. The spinach seeds were treated for 14 hours in an aqueous suspension of iron pyrite nanoparticle (FeS2 + H2O) and thereafter directly sown in the field setup for the experiment. The control seeds were only treated in water for the same duration and sown directly in the field. After 50 days, the crop yields from iron-pyrite nanoparticle treated seeds and control seeds were evaluated. The plants developed from iron pyrite nanoparticle treated seeds exhibited significantly broader leaf morphology, larger leaf numbers, increased biomass; along with higher concentration of calcium, manganese and zinc in the leaves when compared to the plants developed from control seeds. We further investigated the possible mechanism resulting in the biomass enhancement following seed-treatment. Our results indicate that there is an enhanced breakdown of stored starch in the iron pyrite treated seeds resulting in significantly better growth. This raises the possibility of developing iron pyrite nanoparticles as a commercial seed-treatment agent (pro-fertilizer) for spinach crops.

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.

The role of photo-electric properties of silk cocoon membrane in pupal metamorphosis: A natural solar cell.

Silkworm metamorphosis is governed by the intrinsic and extrinsic factors. One key intrinsic factor is the temporal electrical firing of the neuro-secretory cells of the dormant pupae residing inside the silk cocoon membrane (SCM). Extrinsic factors are environmental like temperature, humidity and light. The firing pattern of the cells is a function of the environmental factors that eventually controls the pupal development. How does the nervous organization of the dormant pupae sense the environment even while enclosed inside the cocoon shell? We propose that the SCM does this by capturing the incident light and converting it to electricity in addition to translating the variation in temperature and humidity as an electrical signal. The light to electricity conversion is more pronounced with ultraviolet (UV) frequency. We discovered that a UV sensitive fluorescent quercetin derivative that is present on the SCM and pupal body surface is responsible for generating the observed photo current. Based on these results, we propose an equivalent circuit model of the SCM where an overall electrical output transfers the weather information to pupae, directing its growth. We further discuss the implication of this electrical energy conversion and its utility for consumable electricity.

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.

Escalation of commitment in entrepreneurship-minded groups

Purpose – The purpose of this paper is to investigate commitment escalation tendencies and magnitude in groups of entrepreneurship-minded decision makers. Design/methodology/approach – The paper uses a software-based management simulation to expose 447 graduate business students in the USA and India to research stimuli under conditions that resemble important aspects of entrepreneurs’ business environment, such as a focus on overall firm performance. Unlike most previous escalation research that studied individuals, the primary unit of analysis is a three-person group. Findings – The paper demonstrates a positive relationship between the groups’ entrepreneurial intentions and escalation magnitude. The paper also finds a direct relationship between sunk costs and subsequent investment amounts, suggesting an additional route through which sunk costs may impact escalation behavior – anchoring and insufficient adjustment. Practical implications – The authors hope that the findings will stimulate further resea...

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.

Nano-pyrite seed dressing: a sustainable design for NPK equivalent rice production

AbstractThe use of fertilizers has been the cornerstone in ensuring the global food security. However, the continuous use of excess fertilizers is polluting the water resources and damaging the fragile ecosystem. The key question is ‘how farmers could use lesser fertilizers without reducing crop yields?’ This is a challenge for the sustainable agriculture. Here we showed, in rice crop, seed dressing with nano-pyrite (FeS2), without any addition of NPK (nitrogen, phosphorous and potash) fertilizer, resulted in a comparable yield as obtained following standard fertilizer application. The total grain yields from control (no fertilizer application), standard NPK fertilizer application, ‘FeS2 seed pre-treatment only’ without any application of NPK, NPK + FeS2 treatment were recorded as 1.32 ± 0.0, 1.61 ± 0.1, 1.63 ± 0.1 and 1.68 ± 0.1 [mean (in kg) ± SD], respectively. Interestingly, simultaneous application of FeS2 seed pre-treatment plus fertilizer did not show any significant additive effect. Thus, nano-pyrite seed pre-treatment opens up an ‘NPK equivalent’ strategy for rice production, which could setup a new sustainable paradigm for rice growers.

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.