Bhawna Verma - Academia.edu (original) (raw)

Papers by Bhawna Verma

Diamond and Related Materials

International Journal of Energy Research

Journal of Molecular Structure

Journal of Materials Science: Materials in Electronics

Ternary composites were prepared by varying the weight ratio of the individuals, and their electr... more Ternary composites were prepared by varying the weight ratio of the individuals, and their electrochemical performances were recorded by cyclic voltammetry, charging-discharging, and electrochemical impedance spectroscopy. Polyaniline-acetylene black-cobalt ferrite having the weight ratio of 4:1:2 (aniline:acetylene black:cobalt ferrite) gave outstanding electrochemical outputs. The corresponding system (4:1:2 ratio based system) had 294.49 F/g of specific capacitance at 1 mA of current for the two-electrode configuration. It exhibited the maximum coulombic efficiency of 99.1%. Specific energy and power values are the highest for this system, which are 40.9 Wh/kg and 125 W/kg, respectively. It has quite good capacitance retention of 83.5% after 8000 cycles. The charge transfer resistance is only 1 Ω for this system.

SSRN Electronic Journal, 2022

Materials Technology, 2022

Today, patients suffering from atrial arrhythmias like atrial flutter (AFlut) or atrial fibrillat... more Today, patients suffering from atrial arrhythmias like atrial flutter (AFlut) or atrial fibrillation (AFib) are examined in the EP-lab (electrophysiology lab) in order to understand and treat the disease. Multichannel catheters are advanced into the atria in order to measureelectric signals at manyintracardiacpositions simultaneously. Complementary to clinical learning,comprehension of the disease and therapeutic strategies can be improved with computer modeling of the heart. This way, hypotheses about initiation and perpetuation of the arrhythmia can be tested and ablation strategies can be assessed in-silico. Modeling and biosignal analysis can benefit from mutual fertilization. On the one hand, modeling can be improved and personalization can be achieved via high density mapping of the atria. On the other hand, new algorithms for the interpretation of multichannel electrograms can be developed and evaluated with synthetic signals from computer models of the atria. This article il...

Enzymes play an imminent role as biocatalyst for various biotechnological applications as well as... more Enzymes play an imminent role as biocatalyst for various biotechnological applications as well as production of biodiesel. Here, we focused on the preparation of biosupport materials (polyvinyl alcohol/AlgNa) and their use in immobilization of lipase from Pseudomonas cepacia . Lipase was successfully immobilized onto polyvinyl alcohol/AlgNa in the form of biosupport materials by entrapment method. The mechanical strength, swelling ratio, thermal properties, optimum temperature and pH, lipase loading, leaching, immobilization yields and activity, characterization of the support materials were performed. The optimized pH and temperature for free lipase were 8.0 and 40°C, respectively, while the best pH and temperature for polyvinyl alcohol/AlgNa immobilized lipase were 8.0 and 50°C. 73.12% of the initial activity was retained for the immobilized biosupport catalyst in 6 cycles. The biosupport catalyst beads showed a fascinating degree of immobilized lipase activity along with high imm...

International Journal of Polymer Analysis and Characterization, 2021

International Journal of Energy Research, 2019

A new system based on Polyaniline-Acetylene black-Copper cobaltite composite has been prepared an... more A new system based on Polyaniline-Acetylene black-Copper cobaltite composite has been prepared and affirmed by XRD, UV, SEM, FTIR, and EDS characterizations. The rod-like texture of ternary hybrid system offered excellent electrochemical activity in comparison to single and binary systems. CV and CD results revealed outstanding redox behavior of the ternary hybrid electrodes. Ternary electrode (PACC) presented the highest specific capacitance value of 690 F/g at 1 mA/cm 2 current density. PACC electrode based symmetric supercapacitor had a specific capacitance of 137.25 Fg-1 at 1 mA/cm 2 of current density. PACC symmetric supercapacitor had the highest specific power and specific energy of 3308.85 W.kg-1 and 19.064 Wh.kg-1 , respectively. The ternary system provides less charge transfer resistance values compared to all other systems. Thermal stability of the ternary composite is way better than polyaniline, which is due to the contribution of copper cobaltite and acetylene black. The overwhelming characteristics of the ternary hybrid composite bring it to the limelight as an excellent candidate in the field of supercapacitors.

Chemical Physics Letters, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of Energy Storage, 2019

A novel ternary composite system (polyaniline-acetylene black-manganese cobaltite) was prepared a... more A novel ternary composite system (polyaniline-acetylene black-manganese cobaltite) was prepared and various analysis like XRD, FTIR, UV, SEM, EDS confirmed their successful formation. The EDLC nature of AB and pseudocapacitive nature of PANI and MC provide excellent electrochemical activity to the hybrid system. The calculated areal capacitance of ternary electrode at 1 mA/cm 2 is 1.51 F/cm 2. The areal capacitance of ternary composite based symmetric supercapacitor at 1 mA/cm 2 is 0.35 F/cm 2. Specific power and specific energy achieved by PAMC based symmetric supercapacitor are 2352 W/kg and 18.203 Wh/kg, respectively. Ternary electrode has the least charge transfer resistance i.e. 3.29 Ω. The promising results of ternary hybrid system make it a suitable candidate for supercapacitor applications.

Journal of Cleaner Production, 2019

Fuel, 2019

The main objective of this research was to check the feasibility of producing biodiesel from hybr... more The main objective of this research was to check the feasibility of producing biodiesel from hybrid (Karanja and Castor) oil using bio-support beads immobilized with lipase from Pseudomonas cepacia. Karanja and Castor oil having an acid quantity of 14.71 mg KOH/g and 13.12 mg KOH/g, respectively, were added in equal amounts (50:50%). The fatty acid composition of the hybrid oil contained palmitic (13.4%), linoleic (2.9%), oleic (44.5%), stearic (2.2%) and ricinoleic acid (35.3%). Under the optimized conditions of enzymatic transesterification conditions, i.e. 2-propanol to oil molar ratio-6:1, time-24 h, enzyme (lipase) loading-10% (w/w) and temperature-50 ± 1°C, the biodiesel yield was ∼78%. The reusability of immobilized lipase was tested for 12 cycles by taking 2-propanol as an acyl acceptor under standard conditions in the absence of solvent. After 9 cycles, the bio-support beads could retain up to ∼52% of its initial biodiesel yield. Furthermore, the properties the produced biodiesel were estimated using ASTM D6751 and confirmed by 1 H NMR and FTIR analysis.

Synthetic Metals, 2019

A novel ternary polyaniline-acetylene black-cobalt ferrite hybrid system was synthesized and conf... more A novel ternary polyaniline-acetylene black-cobalt ferrite hybrid system was synthesized and confirmed by XRD, FTIR, UV, SEM, EDS analysis. Ternary composite electrode (PACOF) and the corresponding symmetric supercapacitor had high specific capacitance of 747.64 and 282.35 F/g, respectively at 1 mA. The ternary electrode based symmetric system had 39.218 Wh/kg and 3042.77 W/kg of specific energy and specific power, respectively. The ternary system has the least charge transfer resistance value of 2.3 Ω. Ternary hybrid system has the highest specific capacitance retention (81%) after 6000 cycles. The superior performance of ternary composite was due to the synergistic effects between individual components.

Computers in Biology and Medicine, 2018

Background: During atrial fibrillation, heterogeneities and anisotropies result in a chaotic prop... more Background: During atrial fibrillation, heterogeneities and anisotropies result in a chaotic propagation of the depolarization wavefront. The electrophysiological parameter called conduction velocity (CV) influences the propagation pattern over the atrium. We present a method that determines the regional CV for deformed catheter shapes, which result due to the catheter movement and changing wall contact. Methods: The algorithm selects stable catheter positions, finds the local activation times (LAT), considers the wall contact and calculates all CV estimates within the area covered by the catheter. The method is evaluated with simulated data and then applied to four clinical data sets. Both sinus rhythm activity as well as depolarization wavefronts initiated by stimulation are analysed. The regional CV is compared with the fractionation duration (FD) and peak-to-peak (P2P) voltages. A speed of 0.5m/s was defined to create the simulated LAT. Results: After analyzing the simulated LAT with clinical catheter spatial coordinates, the median CV of 0.5m/s with an interquartile range of 0.22 and exact CV direction vectors were obtained. For clinical cases, the CV magnitude range of 0.08m/s to 1.0m/s was obtained. The P2P amplitude of 0.7mV to 3.7mV and the mean FD from 40.79ms to 48.66ms was obtained. The correlation of 0.86 was observed between CV and P2P amplitude, and 0.62 between CV and FD. Conclusion: In this paper, a method is presented and validated which calculates the CV for the deformed catheter and changing wall contact. In an exemplary clinical data set correlation between regional CV with FD and the P2P voltage was observed. Highlights: • Regional CV calculated for stable catheter positions and individual cardiac excitation. • The algorithm works for different catheter shapes and changing wall contact. • The algorithm has been benchmarked with simulated data. • A novel method to identify critical, slow conducting substrate.

Heat Pipe Science and Technology, An International Journal, 2014

Procedia Technology, 2016

In this paper, we present experimental investigation of convective heat transfer characteristic i... more In this paper, we present experimental investigation of convective heat transfer characteristic in the inner tube fluid of miniature concentric double tube Hairpin heat exchanger with constant heat flux. This work is carried out for distilled water and a mixture of distilled water and ethylene glycol (10%, 20% and 25% by volume) as heat transfer cold fluid flowing in inner tube to carry away heat from the annulus hot fluid. The obtained Friction factor and heat transfer coefficient are compared with the existing conventional correlations. The present experimental results show that mixing of ethylene glycol in distilled water enhances the thermal performance of the miniature heat exchanger considerably for both laminar and turbulent flow in counter flow arrangements. From the experimental results obtained it's also found that thermal performance is better in laminar region than turbulent region.