Dr. D. K. Tiwari | Consejo Nacional de Ciencia y Tecnología (original) (raw)

Papers by Dr. D. K. Tiwari

Microscopy and Microanalysis, 2018

Journal of the Chilean Chemical Society, 2019

All technological innovation that influences research to achieve yields and counteract biotic and... more All technological innovation that influences research to achieve yields and counteract biotic and abiotic stress in crops should be a priority for governments and scientists around the world. Silicon nanoparticles (NpSi) in the production and protection of crops are used as a sustainable strategy. In addition to NpSi, other nanoparticles have been applicable in areas such as environmental remediation, medicine and smart sensors. There are plants that accumulate high concentrations of Si in their tissues, such as "horsetail" (Equisetum arvense). A recent analysis of the elemental composition of E. arvense in a cross section, epidermis, and total biomass indicated that the Si concentration was higher in comparison with macro and micronutrients. Elemental mapping showed that all polymerized silicon (SiO2 • nH2O) is available in the epidermis of Equisetum. Currently, our team is investigating the extraction, purification and quantification of SiNp. The lines of emerging research should be those related to the interaction of SiNp in the cell wall, concentration and intelligent application with aerial equipment in crops such as vegetables, cereals, and fruits.

We present the results of searches for dipolar-type anisotr opies in di fferent energy ranges abo... more We present the results of searches for dipolar-type anisotr opies in di fferent energy ranges above 2.5×1017 eV with the surface detector array of the Pierre Auger Observ ato y, reporting on both the phase and the amplitude measurements of the fir st harmonic modulation in the right-ascension distribution. Upper limits on the am plitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99%C.L. for EeV energies. We also compare our results to those of previous experi ments as well as with some theoretical expectations.

Microscopy and Microanalysis, Jul 22, 2022

Currently there is a high demand for materials that exhibit multifunctional properties, that is, ... more Currently there is a high demand for materials that exhibit multifunctional properties, that is, synthesized compounds with a unique property and an adequate effect that meets various applications in the industrial world. The present study is focused on the synthesis and characterization of two types of nanomaterials: metal oxides and nanomaterial nanocomposites (ferrite and garnet), which were synthesized under the solid state reaction method, using citric acid (C 6 H 8 O 7) as an oxidizing agent in each reaction. On the one hand, the green route was used in the manufacture of metal oxide nanoparticles, where two natural extracts and two different precipitating agents were handled. On the other hand, the garnet and ferrite nanocomposites were made using different doping concentrations. The synthesis of the nanoparticles was carried out at an approximate temperature of 180ºC until crystalline powders were formed. For the elimination of unwanted residues, the samples were subjected to a temperature between 400ºC-600ºC for 4 hours. The characterization of the nanomaterials was carried out using the following techniques: X-ray Diffraction (XRD) (Bruker, D8 Advance), Scanning Electron Microscopy (SEM) / Energy Dispersive X-rays (EDX) (JSM-6390VL SEM-EDX), Fourier transform infrared (FTIR) spectroscopy (PerkinElmer, Frontier), and Raman spectroscopy (Thermo Scientific). The results obtained show hexagonal structures for the metal oxide nanoparticles and a crystal size between 24.44 to 33.74 nm. The garnet nanocomposites present a cubic structure and a crystallite size equal to 57.42 nm. Finally, the ferrite nanocomposites exhibit both cubic and rhombohedral-type structures and have a size ranging from 12.48 nm to 67.73 nm.

Microscopy and Microanalysis, 2018

The growing demands technology and industrial applications catch the interest of researchers for ... more The growing demands technology and industrial applications catch the interest of researchers for developing new materials in application to different areas like communications, computations, automations, biomedical, space. Considering the physical parameters (conductivity, permittivity, skin depth and permeability) of the developing material we focused to work with ferrites because of its easy design versatility with many types of material compounds and also installation alternatives. The properties of ferrites are also dominated by chemical composition, crystalline structure, grain size and nature of porosity. In this study, series of Ba ferrite (BaFe(2-x)MnxO4, at x = 0, 0.2, 0.4 , 0.6, 0.8, 1.0) samples with a substitution of Mn with Fe were prepared by solid state reaction method. The crystalline nature and phase formation were confirmed by XRD measurements. The lattice constant and h, k, l values were obtained using powd software analysis and the prepared material showed the cu...

This paper determines the high energy cosmic rays and their composition. It gives a brief informa... more This paper determines the high energy cosmic rays and their composition. It gives a brief information about the source of origin, flux generation, composition and energy distribution of cosmic rays. This also explains the interactions and particle production of the cosmic ray air showers. The paper also analyzes the energy spectrum which relates to the source of cosmic rays and their propagation to earth over many orders of magnitude in energy. Research also discusses the correlation and interpretation of different observatories. The main analysis is based on the Pierre auger observatory analysis and highest energy cosmic rays with nearby extra galactic matters.

The fast growth of electronic industries advances in the technology and its widespread uses are l... more The fast growth of electronic industries advances in the technology and its widespread uses are leading serious problems due to Electromagnetic interference (EMI). EMI Shielding makes plastic enclosures to protect equipments with EMI; also, increases the protection and safe transmission of data. Looking the design versatility, environmental reliability and good signal/noise ratio, we worked with Nickel-Cobalt Ferrite (Ni1/2Co1/2Fe2O4) materials, which is easy to design with good signal/noise ratio. In the present work, we synthesized the nickel-cobalt ferrite (Ni1/2Co1/2Fe2O4) via citrate route method at room temperature. The crystal structure was verified by the X-Ray Diffraction (XRD) Pattern and dielectric behavior analyzed by using Impedance Analyzer at 100 kHz to 100MHz frequency range with variation of temperature up to 2000C. This material has very good absorption as well as reflection behavior that makes it very useful for high temperature and high frequency applications (EM...

It is well known that, Iron is one of the most important elements of life. Soluble iron is availa... more It is well known that, Iron is one of the most important elements of life. Soluble iron is available to living organisms, iron deficiencies are widespread, and the factors that influence iron solubility are important to understand ecosystem function. Photosynthesis is particularly dependent on iron availability, in part due to the high iron requirements needed to produce chlorophyll [1]. Iron is also essential to animal life and necessary for the health of plants [2], the human body contains 0.006% iron, the majority of which is in the blood. In a healthy adult male total body iron content is 3-5 grams, of which nearly 60% is present in haemoglobin. Every two ml of blood contains one mg of elemental iron [3]. Lack of iron also lowers a person’s resistance to infection. Looking for all these aspects we find that the iron is the most important naturally material and also important of its charge states (Fe2+ & Fe3+), because each charge state has a different role in redox driven metabo...

Microscopy and Microanalysis

Carbon Letters, 2020

Recent years have witnessed remarkable development in the field of nanotechnology and it has been... more Recent years have witnessed remarkable development in the field of nanotechnology and it has been affirmed that carbonbased nanomaterials have wide applications in agriculture, industrial, biomedical and environmental sectors. Due to distinctive physicochemical properties of the carbon nanotubes (CNTs), they have been extensively utilized in plant science as a growth promoter, and thus, could be a boon for biomass production of agricultural products. Studies suggest that CNTs help increase the plant's ability to absorb water and essential nutrients, thereby increasing growth. Apart from this, CNTs have been scrutinized for their utilization in genetic engineering for the delivery of genes, proteins or drugs. However, the literature discloses mixed effects of CNTs exposure on plants like in inducing oxidative stress by generating reactive oxygen species (ROS). Moreover, studies concerning CNTs interaction with plant system is at a nascent stage and needs further investigations to explore the mechanisms influencing the growth and toxicity in plants. Therefore, this review attempts to highlight the current literature on CNTs (including both single walled and multi walled) exposure on plants. It also explores unresolved challenges, as well as recommendations to ensure sustainable development of CNTs while minimizing any possible adverse health impacts.

Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated ca... more Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated carbon (AC), have been seen to significantly increase the growth indices of certain plant species such as maize (Zea mays L.). Seed imbibition is the stage where environmental factors that affect water transport across the seed coat barrier, make a large impact. This work explores the effect on water imbibition by maize seeds when the aqueous environment surrounding the seed is diluted by small concentrations (10 and 20 mg/l) of pristine MWCNT (p-MWCNT), carboxylate functionalized MWCNT (COO-MWCNT) and AC. The degree of sensitivity of the process to (i) large structural changes is seen by utilizing the nano (the MWCNT) and the micro (the AC) allotropic forms of carbon; (ii) to small changes in the purity and morphology of the p-MWCNT by utilizing 95% pure and 99% pure p-MWCNTs of slightly differing morphologies; and (iii) to MWCNT functionalization by using highly pure (97%) COO-MWCNT. Wat...

Microscopy and Microanalysis, 2018

MRS Advances, 2017

Nanocrystalline MnxZn1-xFe2O4 with the varying concentration of Mn (x= 0.25, 0.50) have been synt... more Nanocrystalline MnxZn1-xFe2O4 with the varying concentration of Mn (x= 0.25, 0.50) have been synthesized by citrate route method. The effect of annealing temperature on structural and magnetic properties of as-synthesized materials was studied. The X-ray diffraction (XRD) analysis revealed the improved crystallinity and purity of the samples at high temperature annealing. Also, the increase in the annealing temperature yielded nanocrystals with bigger crystallite size. The samples annealed at higher temperature were analyzed by TEM which showed the formation of irregular polycrystalline particles with average size in the range of 150-180 nm. The magnetic measurements were taken using vibrating sample magnetometer and displayed the superparamagnetic behavior of the prepared materials. Also, the increase in magnetization was observed with Mn substitution.

Instrumentation Science & Technology, 2016

Mn 0.75 Zn 0.25 Fe 2 O 4 nanoparticles were used to characterize magnetic fields using an all fib... more Mn 0.75 Zn 0.25 Fe 2 O 4 nanoparticles were used to characterize magnetic fields using an all fiber Fabry-Perot interferometer. The 20 nm nanoparticles were fabricated with citrate and displayed a coercive field of approximately 10 mT. The nanoparticles were dispersed in oleic acid to prepare a magnetic fluid to fill a Fabry-Perot structure fabricated by arc splicing with conventional single mode and hollow core photonic crystal fibers. This device provided sensitivity and resolution of 0.11 dB/mT and 0.09 mT respectively. Thermal analysis indicated that the magnetic measurements are weakly depending on temperature (0.7 pm/ºC and 7 x 10-3 dB/ºC). This device offers low-cost fabrication, simple implementation, and may be used in several industrial applications.

Journal of Nanobiotechnology, 2016

A recent review article entitled "Carbon and fullerene nanomaterials in plant system" published i... more A recent review article entitled "Carbon and fullerene nanomaterials in plant system" published in this journal, misinterprets a component of our (published) work on the interactions of carbon nanotubes with plants. In this comment, we provide the rationale to counter this misconstruction.

Microscopy and Microanalysis, 2018

Journal of the Chilean Chemical Society, 2019

Microscopy and Microanalysis, Jul 22, 2022

Microscopy and Microanalysis, 2018

Microscopy and Microanalysis

Carbon Letters, 2020

Microscopy and Microanalysis, 2018

MRS Advances, 2017

Instrumentation Science & Technology, 2016

Journal of Nanobiotechnology, 2016

The fast growth of electronic industries advances in the technology and its widespread uses are l... more The fast growth of electronic industries advances in the technology and its widespread uses are leading serious problems due to Electromagnetic interference (EMI). EMI Shielding makes plastic enclosures to protect equipments with EMI; also, increases the protection and safe transmission of data. Looking the design versatility, environmental reliability and good signal/noise ratio, we worked with Nickel-Cobalt Ferrite (Ni1/2Co1/2Fe2O4) materials, which is easy to design with good signal/noise ratio.
In the present work, we synthesized the nickel-cobalt ferrite (Ni1/2Co1/2Fe2O4) via citrate route method at room temperature. The crystal structure was verified by the X-Ray Diffraction (XRD) Pattern and dielectric behavior analyzed by using Impedance Analyzer at 100 kHz to 100MHz frequency range with variation of temperature up to 2000C. This material has very good absorption as well as reflection behavior that makes it very useful for high temperature and high frequency applications (EMI Shielding) and room temperature too. The shielding property of ferrite is strongly influenced by the process parameters and microstructure.