Ashoka Institute of Technology and Management

Ābu Road, India

Ashoka Institute of Technology and Management

Ābu Road, India
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Srivastava G.,Babu Banarasi Das University | Gupta A.,CSIR - Central Electrochemical Research Institute | Singh M.P.,Babu Banarasi Das University | Mishra A.,Ashoka Institute of Technology and Management
Pharmacognosy Journal | Year: 2017

Introduction: Plumeria rubra f. rubra commonly known as Lal Gulachin has wide horizon of medicinal possessions. Plant is found in India and in its tropical regions. Though the plant and its extracts have been indigenously valued as folklore medicine diversely in India, yet literature lacks somewhere in reverse pharmacognostical approach of this plant which reflects that plant have not been evidently explored therapeutically. There are several forms of Plumeria rubra among which P. rubra f. rubra is much appraised in India than its other forms. Method: In Present study the anticipated potential of this plant has been validated by laying down its pharmacognostical standards along with measurement of its active therapeutic constituent Ursolic acid and Lupeol via. HPTLC, information from organized search of published literature remarks that Ursolic acid and lupeol is ubiquitous to this plant. Results: Microscopic features revealed the presence of paracytic type of stomata, crescent bicollateral vascular bundle, calcium oxalate crystal and clothing trichomes in leaves whereas bark showed the presence of distinct periderm with cork and phellogen, sclereids, bast tissue with parenchymatous cells. Methanolic extract of both parts of plant was subjected to HPTLC. In HPTLC studies the Ursolic acid content in leaves was found to be 0.96% whereas in bark was detected as 0.051%, lupeol content in leaves and stem was found to be 0.014% and 0.018%. Conclusion: The data generated could be significantly used as reference for the standardization and quality control of Plumeria. rubra f. rubra, as no such work has been reported yet. © 2017 Phcog.Net.


Chandra B.P.,Ashoka Institute of Technology and Management | Tiwari C.S.,Government Postgaduate College | Sharma R.,Arts and Commerce Girls College
Luminescence | Year: 2013

When an γ-irradiated Dy-, Tm-, Sm- or Mn-doped CaSO4 crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post-deformation region of the crystals. In this study, intensities Im1 and Im2 corresponding to first and second ML peaks, respectively, increased linearly with an impact velocity v0 of the piston used to deform the crystals, and times tm1 and t m2 corresponding to the first and second ML peaks, respectively, decreased with impact velocity. Total ML intensity initially increased with impact velocity and then reached a saturation value for higher values of impact velocity. ML intensity increased with increasing γ-doses and size of crystals. Results showed that the electric field produced as a result of charging of newly-created surfaces caused tunneling of electrons to the valence band of the hole-trapping centres. The free holes generated moved in the valence band and their subsequent recombination with electron trapping centres released energy, thereby resulting in excitation of luminescent centres. Copyright © 2012 John Wiley & Sons, Ltd.


Chandra B.P.,Disha Institute of Management and Technology | Chandra B.P.,Ashoka Institute of Technology and Management | Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Mahobia S.K.,Rani Durgavati University | And 3 more authors.
Sensors and Actuators, A: Physical | Year: 2012

The present paper reports the real-time sensing of the amplitude and duration of impact stress using mechanoluminescence (ML) of the films such as ZnS:Mn and SrAl 2O 4:Eu. After the impact of a small ball from a low height onto the film, initially the elastico mechanoluminescence (EML) intensity increases with time, attains a peak value and then it decreases with time, initially at a fast rate and later on at a slow rate. The fast decay time of the EML intensity is related to the rate constant for the rise of impact stress and the slow decay time of EML is equal to the lifetime of electrons in the shallow traps lying in the normal piezoelectric region of the crystals, which get filled during the detrapping of thermally stable traps at the time of the increase of pressure. Both the peaks of EML intensity and total EML intensity increase linearly with the height through which the ball is dropped onto the films. The EML spectra are similar to the corresponding photoluminescence and electroluminescence spectra. On the basis of the localized piezoelectrically induced electron detrapping model, expressions are derived for different parameters of the impact stress-induced EML of the films, whereby a good agreement is found between the experimental and theoretical results. As the EML intensity depends on the impact stress, the impact stress can be sensed by measuring the EML intensity. Furthermore, the duration of stress is related to the time t m corresponding to the peak of the EML intensity versus time curve; hence, the pulse duration of the impact stress can be monitored by measuring the value of time t m. © 2011 Elsevier B.V. All rights reserved.


Chandra B.P.,Ashoka Institute of Technology and Management | Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Jha P.,Rani Durgavati University | Patel R.,Rani Durgavati University | And 3 more authors.
Journal of Luminescence | Year: 2012

The present paper explores the correlation between fracto- mechanoluminescence and fracture of solids and thereby provides a clear understanding of the physics of fracto-mechanoluminescence. When a fluorescent or non-photoluminescent crystal is fractured impulsively by dropping a load on it, then initially the mechanoluminescence (ML) intensity increases linearly with time, attains a maximum value I m at a particular time t m and later on it decreases exponentially with time. However, when a phosphorescent crystal is fractured impulsively by dropping a load on it, then initially the ML intensity increases linearly with time, attains a maximum value I m at a particular time t m and later on it decreases initially at a fast rate and then at a slow rate. For low impact velocity the value of t m is constant, however, for higher impact velocity t m decreases logarithmally with the increasing impact velocity. Whereas the peak ML intensity I m increases linearly with the impact velocity, the total ML intensity I T, initially increases linearly with the impact velocity and then it tends to attain a saturation value for higher values of the impact velocity. The value of t m increases logarithmally with the thickness of crystals, I m increases linearly with the area of cross-section of crystals and I T increases linearly with the volume of crystals. Generally, the ML of non-irradiated crystals decreases with increasing temperature of crystals. Depending on the prevailing conditions the ML spectra consist of either gas discharge spectra or solid state luminescence spectra or combination of the both. On the basis of the rate of generation of cracks and the rate of creation of new surface area of crystals, expressions are derived for the ML intensity and they are found to explain satisfactorily the temporal, spectral, thermal, crystal-size, impact velocity, surface area, and other characteristics of ML. The present investigation may be useful in designing of damage sensors, fracture sensors, ML-based safety management monitoring system, fuse-system for army warheads, milling machine, etc. The present study may be helpful in understanding the processes involved in earthquakes, earthquake lights and mine-failure as they basically involve fracture of solids. © 2012 Elsevier B.V. All rights reserved.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Ashoka Institute of Technology and Management | Tiwari M.,Rani Durgavati University | Baghel R.N.,Pandit Ravishankar Shukla University | Ramrakhiani M.,Rani Durgavati University
Journal of Luminescence | Year: 2012

When a voltage pulse is applied under forward biased condition to a spin-coated bilayer organic light-emitting diode (OLED), then initially the electroluminescence (EL) intensity appearing after a delay time, increases with time and later on it attains a saturation value. At the end of the voltage pulse, the EL intensity decreases with time, attains a minimum intensity and then it again increases with time, attains a peak value and later on it decreases with time. For the OLEDs, in which the lifetime of trapped carriers is less than the decay time of the EL occurring prior to the onset of overshoot, the EL overshoot begins just after the end of voltage pulse. The overshoot in spin-coated bilayer OLEDs is caused by the presence of an interfacial layer of finite thickness between hole and electron transporting layers in which both transport molecules coexist, whereby the interfacial energy barrier impedes both hole and electron passage. When a voltage pulse is applied to a bilayer OLED, positive and negative space charges are established at the opposite faces of the interfacial layer. Subsequently, the charge recombination occurs with the incoming flux of injected carriers of opposite polarity. When the voltage is turned off, the interfacial charges recombine under the action of their mutual electric field. Thus, after switching off the external voltage the electrons stored in the interface next to the anode cell compartment experience an electric field directed from cathode to anode, and therefore, the electrons move towards the cathode, that is, towards the positive space charge, whereby electronhole recombination gives rise to luminescence. The EL prior to onset of overshoot is caused by the movement of electrons in the electron transporting states, however, the EL in the overshoot region is caused by the movement of detrapped electrons. On the basis of the rate equations for the detrapping and recombination of charge carriers accumulated at the interface expressions are derived for the transient EL intensity I, time t m and intensity I m corresponding to the peak of EL overshoot, total EL intensity I t and decay of the intensity of EL overshoot. In fact, the decay prior to the onset of EL overshoot is the decay of number of electrons moving in the electron transporting states. The ratio I m/I s decreases with increasing value of the applied pulse voltage because I m increases linearly with the amplitude of applied voltage pulse and I s increases nonlinearly and rapidly with the increasing amplitude of applied voltage pulse. The lifetime τ t of electrons at the interface decreases with increasing temperature whereby the dependence of τ t on temperature follows Arrhenius plot. This fact indicates that the detrapping involves thermally-assisted tunneling of electrons. Using the EL overshoot in bilayer OLEDs, the lifetime of the charge carriers at the interface, recombination time of charge carriers, decay time of the EL prior to onset of overshoot, and the time delay between the voltage pulse and onset time of the EL overshoot can be determined. The intense EL overshoot of nanosecond or shorter time duration may be useful in digital communication, and moreover, the EL overshoot gives important information about the processes involving injection, transport and recombination of charge carriers. The criteria for appearance of EL overshoot in bilayer OLEDs are explored. A good agreement is found between the theoretical and experimental results. © 2012 Elsevier B.V.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Disha Institute of Management and Technology | Chandra B.P.,Ashoka Institute of Technology and Management
Organic Electronics: physics, materials, applications | Year: 2012

In phosphorescent organic light-emitting diodes (PHOLEDs), both the rise time and decay time decrease with increasing amplitude of the applied voltage pulse. The rise time τ r of the transient electroluminescence (TEL) increases linearly with increasing value of the ratio of voltage V to the current j, that is, with V/j. Using the equations for the dynamics of charge carriers an expression is derived for the rise time τ r of the TEL in OLEDs. It is shown that τ r should increase with increasing values of the ratio (V/j), dielectric constant , and area of cross-section of the emission layer, however, it should decrease with the thickness of emission layer. For higher values of the applied voltage nonlinearity occurs in the τ r versus V/j plot because the increase in mobility of carriers at high electric field causes increase in the current flowing through the OLEDs. In fact, the rise time of TEL is related to the product of capacitance and effective resistance of the OLED. Considering the rate of generation and decay of radiative triplet excitons in the emission layer, an expression is derived for the decay time of TEL in PHOLEDs and it is shown that, for higher values of the time-constant of OLED, the decay time should be equal to the time-constant, however, for lower values of the time-constant, the decay time should be equal to the lifetime of radiative triplet excitons in the emission layer. A good agreement is found between the theoretical and experimental results. © 2011 Elsevier B.V. All rights reserved.


Pervez Y.,Chhatrapati Shivaji Institute of Technology | Janghel E.K.,Ashoka Institute of Technology and Management | Sar S.K.,Bhilai Institute of Technology
Asian Journal of Chemistry | Year: 2016

Flow injection spectrophotometric method is developed for the determination of cypermethrin insecticide. The method is based on alkaline hydrolysis of cypermethrin is converted into 2-diphenyl ether cyano ethane and hydrolyzed with HCl and resulting product was diazotized with nitrate and coupled with aniline. The absorption maxima of the azo dye formed is measured at 535 nm in acidic medium. Beer's law is obeyed over the concentration range of 5.5 to 36 μg/25 mL. The molar absorptivity and Sandell's sensitivity were found to be 5.3 × 104 L mol-1 cm-1 and 0.066 μg cm-2, respectively. The standard deviation and relative standard deviation were found to be ± 0.003 and 0.56 %, respectively. The % recovery for the determination of cypermethrin was found to be 92 %. The sampling frequency was 80 samples per hour for flow injection analysis. The method is simple sensitive and free from interferences of other pesticides and diverse ions. Other pyrethroid insecticides do not interfere in the proposed method. The method is simple, fast and has been satisfactorily applied to the determination of cypermethrin in commercial formation, food and environmental sample.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Disha Institute of Management and Technology | Chandra B.P.,Ashoka Institute of Technology and Management
Journal of Luminescence | Year: 2012

When a composite of suitable dimension formed by mixing the microcrystalline or nanocrystalline persistent luminescent materials in epoxy resin is deformed at a fixed pressing rate, then the elastico mechanoluminescence (EML) emission takes place after a threshold pressure, in which the EML intensity increases linearly with the applied pressure. When the applied pressure is kept constant or decreased linearly, then the EML intensity decreases with time, in which depending on the prevailing condition, the EML intensity initially decreases at a fast rate and then at a slow rate or sometimes it decreases exponentially having only one decay time. When a small ball is dropped from a low height onto the film of a persistent luminescent material, then initially the EML intensity increases with time, attains a peak value and then it decreases initially at a fast rate and later on at a slow rate. In this case, both the peak EML intensity and the total EML intensity increase linearly with the height through which the ball is dropped onto the film. Considering the piezoelectrically induced detrapping model based on successive detrapping of exponentially distributed traps a theoretical approach is made to the dynamics of light emission induced by elastic deformation of persistent luminescent crystals and thin films. It is shown that the EML intensity depends on several parameters such as pressure, pressing rate or strain rate, temperature, density of filled electron traps, piezoelectric constant near defect centers, etc. Both, in the case of slow deformation and impact stress, the fast decay time is related to the time-constant for the decrease of pressing rate of the samples and the slow decay time of EML is related to the lifetime of electrons in the shallow traps lying in the normal piezoelectric region of the crystals. Both, the EML produced during the release of pressure and the EML produced during the successive applications of pressure take place due to the detrapping of retrapped electrons in the vacant electron traps near activator ions, in which retrapping is caused by the thermally released electrons from the filled shallow traps lying in the normal piezoelectric region of the crystals, which get filled during the detrapping of stable traps at the time of increase of pressure. On the basis of the proposed model, the dependence of EML intensity on different parameters, dynamics of EML and physical concepts of the threshold pressure, characteristic piezoelectric field for detrapping, coefficient of deformation detrapping, nonlinear increase of the EML intensity of some crystals at high pressure and higher EML intensity in the crystals having higher coefficient of deformation detrapping can be satisfactorily understood. A good agreement is found between the theoretical and experimental results. It is shown that the present study may be helpful in tailoring the intense persistent elastico mechanoluminescent materials having long lasting time. © 2011 Elsevier B.V. All rights reserved.


Singh D.,Ashoka Institute of Technology and Management | Singh B.,Indian Institute of Technology BHU Varanasi | Singh N.,Motilal Nehru National Institute of Technology
International Journal of Power Electronics and Drive Systems | Year: 2014

This paper presents a framework to carry out a simulation to tune the speed controller gains for known input of DC drive system. The objective is to find the optimal controller gains (proportional and integral) in a closed loop system. Various performance indices have been considered as optimal criterion in this work. The optimal gain values have been obtained by conventional and Genetic Algorithm (GA) based optimization methods. The study has been conducted on a simulink model of three phase converter controlled direct current (DC) drive with current and speed control strategy. The results show that the GA based tunning provided better solutions as compared to conventional optimization methods based tunning. © 2014 Institute of Advanced Engineering and Science. All rights reserved.


PubMed | Ashoka Institute of Technology and Management
Type: Journal Article | Journal: Luminescence : the journal of biological and chemical luminescence | Year: 2013

When an -irradiated Dy-, Tm-, Sm- or Mn-doped CaSO4 crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post-deformation region of the crystals. In this study, intensities Im1 and Im2 corresponding to first and second ML peaks, respectively, increased linearly with an impact velocity v0 of the piston used to deform the crystals, and times tm1 and tm2 corresponding to the first and second ML peaks, respectively, decreased with impact velocity. Total ML intensity initially increased with impact velocity and then reached a saturation value for higher values of impact velocity. ML intensity increased with increasing -doses and size of crystals. Results showed that the electric field produced as a result of charging of newly-created surfaces caused tunneling of electrons to the valence band of the hole-trapping centres. The free holes generated moved in the valence band and their subsequent recombination with electron trapping centres released energy, thereby resulting in excitation of luminescent centres.

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