SK Chakarvarti

MRIU, RESEARCH & DEVELOPMENT, Emeritus

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Former Pofessor and Dean Academic at National Institute of Technology,Kurukshetra,India

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Papers by SK Chakarvarti

Investigation of Ionic Transport Through Track-Etched Conical Nanopores of PET Membrane

Nano, 2018

The control of ionic transportation inside the multi asymmetric conical nanopores in polyethylene... more The control of ionic transportation inside the multi asymmetric conical nanopores in polyethylene terephthalate (PET) membrane was investigated. The conical nanopores were prepared by chemical etching in irradiated PET foil using etchant (9 M NaOH) and stopping solution (1 M NaCl [Formula: see text] 1 M HCOOH). The behavior of ionic current was recorded under stepping voltage [Formula: see text]2[Formula: see text]V to [Formula: see text]2[Formula: see text]V at different molar concentrations of potassium halides (KCl, KBr and KI) under symmetric bathing condition in electrochemical cell. It is found that the presence of multiple ionic species and the occurrence of counterion condensation of charge regulated polyelectrolyte play an effective role in ionic current rectification (ICR). The electrical conductance of conical nanopores may be estimated by measuring the ionic current rectification properties of track-etched nanopores. The charge transport properties vary with molar concen...

Synthesis of Microwires of Polypyrrole via Chemical Polymerization using Track Etch Membrane as Template

American Journal of Materials Science and Technology, 2014

Low dimensional structures of conducting polymers, particularly polypyrrole, have attracted a gre... more Low dimensional structures of conducting polymers, particularly polypyrrole, have attracted a great attention of researchers and engineers in recent years because of their diverse potential application on account of their unique properties of large aspect ratio, good electrical conductivity, environmental stability and biocompatibility. The present work describes synthesis of polypyrolle microwires by template assisted chemical polymerization at room temperature using FeCl3 as an oxidant. In this technique, the track etch membrane used as a template was fitted between two chambers in a chemical cell in such a way that the template acts as a separating wall between the chambers. One chamber was filled with an aqueous monomer pyrrole solution and other was filled with oxidant reagent of ferric chloride. Chemical polymerization takes place within the pores of the template as the monomer and the oxidant reagent diffuse towards each other, react to yield the conductive polymer which grows as microstructure in the shape of pores of host template. Synthesized samples have been characterized by Scanning Electron Microscopy (SEM), which reveals that the morphology of the microwires matches with the morphology of pores as mould in host template. Diameter, orientation and direction of growth of microwires were almost uniform because of the confined growth of microwires in the ordered and symmetric pores of TEM template. Conductivity of polypyrrole microwires was estimated equal 20.152 S/m form current-voltage characteristics measured using a two-probe-method.

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IONIC CURRENT RECTIFICATION THROUGH pH-REGULATED NANOPORES

This research article reports the pH dependent ionic current rectification (charge transport) in ... more This research article reports the pH dependent ionic current rectification (charge transport) in track-etched cylindrical nanopores of polycarbonate (PC). For preparation of cylindrical nanopores, irradiated PC foil was chemically etched with 6M NaOH solution on both sides in electrochemical cell. The behavior of ionic transportation was recorded with stepping voltage at different ionic concentrations and the pH of electrolytic solution under symmetric and asymmetric condition in an electrolytic cell. The results revealed that bulk concentration and pH of electrolytic solution significantly influence the ionic conductance. Under highly asymmetric pH condition, the nanopores behaves like solid state p-n junction diode and rectification through the nanopores was observed. The functional carboxylic group (-COOH) and movable ions of electrolytic solution inside the nanopores wall are found responsible for ionic current transportation (ICT) but for ionic current rectification (ICR), asym...

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Morphology of etched pores and microstructures fabricated from nuclear track filters

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1991

Of the many potent technological applications c`nuclear track filters (NTFs), fabrication of micr... more Of the many potent technological applications c`nuclear track filters (NTFs), fabrication of micro and ultramicrostructures is one of the most useful spin-offs finding immediate use in awide range of fields including microelectronics. We report here simple methods of fabrication and morphological investigations on such microstructures and the pores of NTFs. Electrodeposition of copper metal into the etched pores of Makrofol KG, Makrofol N, Kapton-H, and Polyester NTFs with different thickness and porosity hasbeen used to fab,icate and reveal the profiles of the structural element3 as well as of the pores which actas templates for such structural growths. Some comparative investigations are also presented otti non-electrochemical methods of replication .

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Implementation and Analysis of Reversible logic Based Arithmetic Logic Unit

TELKOMNIKA (Telecommunication Computing Electronics and Control), 2016

There is a tremendous growth in fabrication from small scale integration (SSI) to giant scale int... more There is a tremendous growth in fabrication from small scale integration (SSI) to giant scale integration (GSI). It however raises a question of sustainability of Moore's law due to almost intolerable levels of power consumption. Researchers have invented a lot of methods to reduce power consumption and recent technologies are switching to reversible logic. Reversible logic has various applications in fields of computer graphics, optical information processing, quantum computing, DNA computing, ultra low power CMOS design and communication. ALU is considered to be the basic building block of a CPU in the computing environment and portability in computing system highly demands reversible logic based ALU. Modern processors usually have a word length of 32 or 64 bits. Divide and conquer approach principle cascades n number of 1 bit ALU to implement n bit ALU. Several researchers have proposed 1-bit ALU design using various reversible logic gates. This paper aims at categorizing various ways of implementation in VHDL using Xilinx ISE design suit 14.2 tool and comparative analysis of existing 1 bit ALU designs in terms of optimization metrics like power consumption, number of gates, number of constant inputs, number of garbage outputs and quantum cost .ALU realized using carry save adder block is found to be most optimum design in terms of gate count and quantum cost.

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A Review on Wireless Body Area Network (WBAN) for Health Monitoring System: Implementation Protocols

Communications on Applied Electronics, 2016

As in the present era use of wireless networks is increasing day by day and the electrical device... more As in the present era use of wireless networks is increasing day by day and the electrical devices are getting smaller; both factors expand the research area of Wireless Body Area Networks(WBAN).The devices used in WBAN can record various physiological parameters like the body temperature, the BP or to take ECG, EEG, etc. With the use of WBAN, a patient experiences a greater physical mobility. The patients need not stay longer in the hospital as WBANs are placed on the human body and often transport private data; Security is considered as an important issue. It will in turn increase the quality of patient care and the productivity of hospital staff. Field of Wireless Body Area Networks comes up as a major research area in past few years as it is beneficial in health monitoring even in remote areas and patient's care can be done in real time. However, if the security of patient's data is concerned with WBANs, design issues should be taken care of. In the present paper, a short review on various aspects of Wireless Body area Network, various implementation techniques and MAC protocols are discussed. The technique which is best suited to the user is also presented.

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Activity concentration and annual effective ingestion dose assessment due to natural radionuclides present in cereal samples consumed by inhabitants of India

International Journal of Low Radiation, 2015

In the present study, activity concentration and annual effective ingestion dose assessment was c... more In the present study, activity concentration and annual effective ingestion dose assessment was carried out in cereal samples using gamma spectrometry. In the studied samples the activity of 226Ra, 238U, 232Th, and 40K varied from 10.25±0.94 Bq/kg to 29.13±0.69 Bq/kg, 7.04±0.13 Bq/kg to 20.08±1.32 Bq/kg, 22.20±2.46 Bq/kg to 58.21±1.15 Bq/kg and 1158.4±26.05Bq/kg to 1962.2±18.17 Bq/kg with an average value of 20.06±4.82 Bq/kg, 13.08±1.31 Bq/kg, 41.53±3.77 Bq/kg, and 1639±75.55 Bq/kg respectively. The average value of annual effective ingestion dose from ingested food was 0.62±0.08 mSv/y, 0.07±0.006 mSv/y, 1.20±0.11 mSv/y, and 1.28±0.06 mSv/y from 226Ra, 238U, 232Th, and 40K, respectively. The average value of total ingestion dose and cancer risk was found to be 3.18±0.14 mSv/y and (79.5±3.55) × 10−4 respectively.

Use of Non-Invasive Ultrasonic Techniques in Process Instrumentation and Measurements

IETE Technical Review, 1986

ABSTRACT Instrumentation and measurement technology embrace undoubtedly the techniques which offe... more ABSTRACT Instrumentation and measurement technology embrace undoubtedly the techniques which offer various attractive features like non-invasive use. Ultrasonic sensors are adorned with this quality and hence offer most of the measurements non-invasively. The applications of ultrasonic sensors broadly classified into three categories viz power ultrasonic tools; signal processing devices and ultrasonic instruments exploiting ultrasonic frequency stress waves, are given here for the measurement of various physical parameters. Based upon one or more variabilities of these categories, ultrasonic sensors are used in the chemical and process industries.

Radiation hormesis: the validity of the linear no-threshold hypothesis

International Journal of Low Radiation, 2006

Through various researches and investigations it has been established that high doses of ionising... more

Bulk-etching behaviour of Kapton and Thermalimide track detectors

International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements, 1992

Polyimides and polyetherimides have recently been recognized as materials with unique properties ... more Polyimides and polyetherimides have recently been recognized as materials with unique properties which are essential for the production of more efficient and useful nuclear track filters. We report here the bulk-etch characteristics of Kapton-H (polyimide) and Thermalimide foils using etchants NaOCl (4% Cl w/v) and NaOCl + ethanol (1: 1) at different temperatures and under ambient light and dark conditions, with and without stirring. The activation energy values for etching are also reported.

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A Model for Cu-Se Resonant Tunneling Diodes Fabricated by Negative Template Assisted Electrodeposition Technique

Communications and Network, 2010

In this paper, the authors present and discuss a model for Cu-Se nano resonant tunneling diodes (... more

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Alpha radioactivity measurements in tobacco leaves

Radon diffusion studies through building construction materials using solid state nuclear track detectors

Radium concentration and radon exhalation rates from some soil samples using solid state nuclear track detectors

MODIFIED SWITCHING CHARACTERISTICS OF CARBON NANOTUBES BLENDED WITH TYPE II CdTe QUANTUM DOTS

We have investigated the electrical properties of the hetero structures deposited on conductive g... more We have investigated the electrical properties of the hetero structures deposited on conductive glass. The hetero structures made with type II CdTe quantum dots present interesting peculiarities. Low frequency (20Hz ≤ f≤ 200kHz; f= 8804) dielectric properties of type II CdTe, type II CdTe blended with Single-wall carbon nano tubes SWNTs functionalized with poly (ethylene glycol ) hetero junctions, were investigated in details at room temperature. Negative capacitance was observed at low frequencies under forward dc biases. . By using frequency dependent capacitance spectroscopy, the tunnelling effects of holes and electrons were investigated. Peaks were observed In capacitance curves measured at low frequency, which could be attributed to the resonant tunnelling of charge carries into discrete energy levels of nanocrystalline CdTe and exhibit quantum confinement and coulomb blockade effects. A clear (positive/negative) shift in capacitance-voltage(C-V) and conductance-voltage (G-V) suggests (electron/hole) trapping in nanocrystalline quantum dots.

Environmental radon monitoring in gas turbine power station in Haryana

Measurement of inhalation dose due to radon and its progeny in an oil refinery and its dwellings

Background: Radon, an invisible, odorless, heaviest (nine times heavier than air) and radioactive... more Background: Radon, an invisible, odorless, heaviest (nine times heavier than air) and radioactive gas is an aberration (the only gas in the long decay chain of heavy metal elements). It is ubiquitously present in dwellings and in the environment. Humans receive the greatest radiation dose in their homes. That's where they spend most time-typically 70%, more for small children. Recent worldwide surveys reveal that an average person receives each year more radiation from radon than from all other natural or man-made sources combined. Over the years, the radiation exposure accumulated at home may exceed the exposure of uranium miners and lead to lung disorders. Therefore it is fundamental and justified to make a quantitative assessment of the radon in dwellings and the environment of work place. In this study, measurement of radon and its progeny levels was carried out in the environment of an oil refinery. Besides, radon and its progeny levels were also measured in the dwellings situated on the refinery premises and the dwellings in the city for comparison. Materials and Methods: LR-115, Type-II (Kodak Pathe, France), plastic track detectors commonly known as solid state nuclear track detectors (SSNTDs) were used to measure the radon concentration over long integrated times. Alpha particles emitted from radon cause radiation damage tracks, which were subsequently revealed by chemical etching in NaOH. These alpha tracks registered were counted by optical microscope at suitable magnification and converted into radon concentration. Results: The geometric means (GM) of potential alpha energy concentration (PAEC), Equilibrium Equivalent Concentration of radon (EEC value), annual exposure and annual effective dose in the environment of refinery premises was 10.09 mWL, 93.43 Bq m-3 , 0.41 WLM and 1.61 mSv, in refinery dwellings 12.21 mWL, 112.96 Bq m-3 , 0.50 WLM and 1.94 mSv and in city dwellings 8.24 mWL, 76.23 Bq m-3 , 0.34 WLM and 1.31 mSv respectively. Conclusion: The dose levels in the refinery premises were found to be marginally below the ICRP recommendations. The radon and its progeny levels were higher in the dwellings of refinery township as compared to the city dwellings. While studying seasonal variation, it was found that the measured values of radon and its progeny levels were higher in winter (November to February) than in summer (May to August). This study showed that the presence of fossil fuels like natural gas, LPG etc. in the environment had resulted into higher levels of radon and its progeny in the refinery dwellings.

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Electrical Properties of Electrodeposited ZnCuTe Ternary Nanowires Embedded in Polycarbonate Membrane

Nanomaterials and Nanotechnology, 2012

The electrical properties of electrodeposited zinc-copper-telluride (ZnCuTe) nanowires embedded i... more The electrical properties of electrodeposited zinc-copper-telluride (ZnCuTe) nanowires embedded in polycarbonate track-etch membrane (Whatman) having pore-diameters of 200, 100 and 50nm have been studied and reported in this paper. Scanning electron microscopy (SEM) confirmed the formation of the nanowires of uniform diameter equal to the diameter of the templates used. I-V measurements at room temperature (303K) reveal that the nanowires of diameter 200, 100 and 50nm have linear and ohmic characteristics. Higher electron transport was observed in larger diameter nanowires compared to smaller ones which may be attributing to size effect. The temperature-dependent electrical transport measurements over a temperature range 308-423K reveal that the temperature dependence of electrical conductivity increases with increasing temperature and decreases as the nanowires size decreases. The study reveals that ZnCuTe nanowires have negative temperature coefficient of resistance (TCR).

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Electrochemical synthesis of metallic micro-rose having petals in nanometer dimensions

Superlattices and Microstructures, 2008

Nature plays a big role through chemico-physical phenomenon in defining the morphological feature... more

Study of radon diffusion from RHA-modified ordinary Portland cement using SSNTD technique

Radiation Measurements, 2013

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SK Chakarvarti

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