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TEMPO mediated electrocatalytic oxidation of pyridyl carbinol using palladium nanoparticles dispersed on biomass derived porous nanoparticles
Remarkable electrocatalytic property of Pd nanostructures dispersed on CNSareca coated CFP electrode towards TEMPO mediated electrooxidation of pyridyl carbinol was reported for the first time. Carbon nanospheres (CNSs) derived from Areca catechu decorated with Pd nanoparticles were coated on carbon fiber paper (CFP) and was employed for electrooxidation of pyridyl carbinol in aqueous acidic medium. An environmentally benign and economic strategy was utilized for the preparation of CNSs obtained from Areca catechu. The physical characterizations, electronic state and chemical composition of the modified electrode were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) techniques were used for analyzing the morphology of modified electrode. The electrochemical characterizations of the modified electrodes were performed by Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS). Pd decorated CNSareca dispersed on CFP electrode has exhibited strong electrocatalytic activity towards TEMPO mediated oxidation of pyridyl carbinol. 2020 Elsevier Ltd -
MnO2-Pi on biomass derived porous carbon for electro-catalytic oxidation of pyridyl carbinol
A facile electrochemical oxidation of pyridyl carbinol based on Manganese dioxide-Phosphate (MnO2-Pi) was fabricated by electro-deposition of MnO2-Pi on Porous carbon nanospheres (PCN) modified carbon fiber paper (CFP) electrode. A simple working electrode was developed initially by coating Monkey Pod (MP) derived PCN on carbon fiber paper (CFP) electrode. Voltammetric deposition of MnO2-Pi on PCN/CFP electrode was carried out in an electrolyte containing phosphate buffer and KMnO4. The modified electrodes (PCN/CFP and MnO2-Pi-PCN/CFP) were characterized by different physicochemical methods and electroanalytical techniques like cyclic voltammetry and AC impedance spectroscopy. Inorganic phosphate (Pi) and MnO2 centers present on PCN/CFP electrode plays a major role towards oxidation of pyridyl carbinol electrochemically. The proposed MnO2-Pi-PCN/CFP electrode was effectively applied for the electrochemical oxidation of pyridyl carbinol in TEMPO medium. 2020 The Author(s). -
An aqueous phase TEMPO mediated electrooxidation of 2-thiophenemethanol using MnO2-Pi dispersed nanocarbon spheres on a carbon fiber paper electrode
An environmentally benign and economic method was developed for the electrocatalytic oxidation of 2-thiophenemethanol in an aqueous acidic medium. Nanocarbon spheres (NCS) coated on carbon fiber paper (CFP) were used as a host matrix to disperse manganese dioxide nanoparticles from phosphate buffer solution through electrochemical deposition. The developed electrode (MnO2-Pi-NCS/CFP) was used as a working electrode for electrochemical oxidation of 2-thiophenemethanol in the presence of a mediator TEMPO in 0.01 M H2SO4 medium. Different analytical methods were used to characterize the modified electrodes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties of the modified electrodes. The electrochemically active surface area values calculated for bare CFP, NCS coated CFP and MnO2-Pi-NCS/CFP electrodes were found to be 1.43 cm2, 2.86 cm2, and 6.72 cm2 respectively for the geometric area of 0.7 cm2 of the electrodes. Coating of NCS and MnO2-Pi resulted in porosity and roughness of the CFP electrode which enhances the surface area. MnO2-Pi-NCS/CFP demonstrated higher electrocatalytic activity for oxidation of 2-thiophenemethanol to 2-thiophenemethanal in aqueous acidic media with a TEMPO mediator compared to unmodified electrodes. This journal is 2021 The Royal Society of Chemistry. -
Spectroscopic Study Of Selected Be Stars In Our Galaxy
The optical spectroscopic monitoring observation of two Be stars namely 4 Hercules and 88 Hercules was observed with 1.02m telescope at the VBO, Tamil Nadu, India over a period of six months. The spectra were reduced using standard routines in IRAF. The equivalent width of the lines were identified have been measured. The line profile variability exhibited by H? H?and HeI lines are studied to understand the emission mechanism in the Classical Be-stars. The properties of the process can be well constrained, leaving only few options, most importantly, but not exclusively, non-radial pulsation and small scale magnetic fields. In different stars different processes may be acting. This is not only true for the disk structure, but as well for its variability, both cyclic and secular. Be stars, at lower metallicities, seem more common and more rapidly rotating. The Be phenomenon, linked with one or more mass ejection processes, acts on top of a rotation rate of about 75% of critical or above. In this work, first the definition of Be-stars is contrasted to similar classes, and common observables obtaind for Be-stars are introduced and the respective formation mechanism explained. The current state of knowledge concerning the central stars as non-radially pulsating objects and non-magnetic stars, as far as it concerns large scale. The weak magnetic fields remain possible, but are of yet unproven. In this dissertation Chapter 1 discusses the features of Be- stars and reviewed the progress made in understanding Be-stars in the recent past. Chapter 2 discusses the literature review. Chapter 3 describes the methodology carried out to study the objective. Chapter 4 explains the result and analysis part of the research. Chapter 5 is about the conclusions. -
Excitation Mechanism of Oi Lines in Herbig Ae/Be Stars
We have investigated the role of a few prominent excitation mechanisms viz. collisional excitation, recombination, continuum fluorescence, and Lyman beta fluorescence on the O i line spectra in Herbig Ae/Be stars. The aim is to understand which of them is the central mechanism that explains the observed O i line strengths. The study is based on an analysis of the observed optical spectra of 62 Herbig Ae/Be stars and near-infrared spectra of 17 Herbig Ae/Be stars. The strong correlation observed between the line fluxes of O i ?8446 and O i ?11287, as well as a high positive correlation between the line strengths of O i ?8446 and H? suggest that Lyman beta fluorescence is the dominant excitation mechanism for the formation of O i emission lines in Herbig Ae/Be stars. Furthermore, from an analysis of the emission line fluxes of O i ??7774, 8446, and comparing the line ratios with those predicted by theoretical models, we assessed the contribution of collisional excitation in the formation of O i emission lines. 2018 The American Astronomical Society. All rights reserved.. -
Accumulation of lead (Pb II) metal ions by Bacillus toyonensis SCE1 species, innate to industrial-area ground water and nanoparticle synthesis
Groundwater samples were collected from Peenya Industrial area of Bengaluru, India to check its inherent bacterial population. After the isolates were grown in lead-induced media, the bacteria that could resist lead were further isolated, identified, and grown. The isolated bacterium was identified as Bacillus toyonensis SCE1 species, and the maximum amount of lead taken up by it to sustain itself as a live biomass was 8ppm. Lead accumulation was studied based on different factors such as pH, concentration, and time. Bacterial characterization through scanning electron microscopy showed there was lead sorption on the bacterial cells. Transmission electron microscopy revealed that accumulated lead ions inside the bacteria were in the range of 180190nm, this was found to correlate with the data obtained by the particle size analyzer. The optimum pH for highest lead accumulation was 7.2, for a time period of 160min. It was observed that the stable production of homogenous nanoparticles using biomass could be achieved by optimizing factors such as incubation period, agitation, pH, temperature, and contact time. 2018, Springer-Verlag GmbH Germany, part of Springer Nature. -
Role of Bioadsorbents in Reducing Toxic Metals
Industrialization and urbanization have led to the release of increasing amounts of heavy metals into the environment. Metal ion contamination of drinking water and waste water is a serious ongoing problem especially with high toxic metals such as lead and cadmium and less toxic metals such as copper and zinc. Several biological materials have attracted many researchers and scientists as they offer both cheap and effective removal of heavy metals from waste water. Therefore it is urgent to study and explore all possible sources of agrobased inexpensive adsorbents for their feasibility in the removal of heavy metals. The objective was to study inexpensive adsorbents like various agricultural wastes such as sugarcane bagasse, rice husk, oil palm shell, coconut shell, and coconut husk in eliminating heavy metals from waste water and their utilization possibilities based on our research and literature survey. It also shows the significance of developing and evaluating new potential biosorbents in the near future with higher adsorption capacity and greater reusable options. 2016 Blessy Baby Mathew et al. -
Composites based on natural polymers
Polymers are composed of macromolecules of high molecular weight formed by the repeated union of small molecules known as monomers. Polymer materials over other materials such as metals and ceramics, are of light weight and hence extensively used. The use of renewable raw materials can provide a substantial activity for a sustainable society and environment. Natural polymer composites can provide an alternative to increasingly scarce raw materials from plants and animals. 2017 Nova Science Publishers, Inc. -
Classification, source, and effect of environmental pollutants and their biodegradation
Any foreign chemical substance that is unusually present within an organism or is unexpectedly found in the environment at a higher concentration than the permissible limits can be termed a xenobiotic or a pollutant. Such substances include carcinogens, drugs, food additives, hydrocarbons, dioxins, polychlorinated biphenyls, pesticides or even some natural compounds. Pollutants are known for their higher persistence and pervasiveness, and along with their transformed products, they can remain in and interact with the environment for prolonged periods. In this article, the classification of such substances based on their nature, use, physical state, pathophysiological effects, and sources is discussed. The effects of pollutants on the environment, their biotransformation in terms of bioaccumulation, and the different types of remediation such as in situ and ex situ remediation, are also presented. 2017 Begell House, Inc. -
Human behavior analysis of BBC-news comments posted on facebook using lexicon-rule based approach
Today people spend a considerable part of their time on online platforms say, social media than with the real world. Social media, particularly Facebook is the platform for the users to post, share, like, tag and comment any photos and videos. This paper deals with the Facebook platform to study the human behavior based on the comments of five posts from BBC-news Facebook page. For every post in Facebook we can get different opinion or emotional behavior by different users. The behavior of people to the same event need not be similar, they can be different. A response through comments and smileys for a post portrays behaviors of people. Here the behavior analysis is performed on comments of the BBC news Facebook posts. The comments of the post are fetched by the online extractor named Socialfy [12]. This paper considered five news from unique from BBC-news Facebook page. The human behavior analysis performed using Python VADER (Valence Aware Dictionary and Sentiment Reasoner) package. This work uses the Lexicon approach to assign scores for the words and rule-based approach used to find the polarity type of words. The polarity of a post is the sentimental behavior of the people towards the post. The total polarity of this work tends towards neutral so, we could conclude that for each situation behavior of man can take positive or negative poles. 2019, Institute of Advanced Scientific Research, Inc. All rights reserved. -
Evaluation of morpho-cellular and spectroscopic characteristics of Myristica fragrans Houtt mace across three different maturation stages (juvenile, raw and ripe)
This study was based on comprehensive analysis of Myristica fragrans Houtt mace samples across various stages of maturation (juvenile, raw and ripe). The anatomical analysis was performed using SEM coupled EDX spectroscopy that revealed distinct cellular changes and the presence of oil-storage structures in the mace. The EDX analysis further confirmed the presence of key elements such as carbon (C), oxygen (O) and potassium (K) which contribute to mace's pharmacological properties. Spectrophotometric analysis revealed a steady increase in chlorophyll content as the mace matures, with total chlorophyll content rising from 1.02 during the juvenile stage to 1.25 at the raw stage and reaching 3.29 at the ripe stage. The Plant Senescence Reflectance Index (PSRI) shows a rise in carotenoid content, increasing from 0.15 in the juvenile stage to 0.17 at the raw stage and reaching 0.82 at the ripe stage. This increase correlates with the mace's colour transformation to crimson red during ripening. The FTIR spectroscopy analysis provided a detailed chemical characterization of the mace, identified various functional groups (carboxylic acid, aldehyde, alkanes, azides) and organic molecules. The presence of multiple functional groups across the maturation stages suggested a complex composition that likely contributes to the mace's sensory and pharmacological qualities. 2024 World Researchers Associations. All rights reserved. -
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Enhancement of the Electrochemical behaviour of Carbon Black via a defect induced approach
In order to address the rising global concern of energy storage, carbon-based materials have established themselves due to their distinct features. Despite the demand for the fabrication of supercapacitors from natural, inexpensive carbonaceous materials is on the rise, the intrinsic disorders present in such materials hinder their performance, and hence, tuning these defects can aid in the improvement of their electrochemical performance. In this study, carbon black is introduced with defects in the form of oxygen functional groups via oxidation and thermal exfoliation and the impact on its electrochemical performance is studied. Careful tuning of the type of oxygen functional moieties at the basal plane of the carbon lattice is observed to be the contributing factor for the electrochemical behaviour. The distortion in the graphitic lattice caused by the epoxy and hydroxyl groups alters the specific surface area, porosity, and thermal stability, facilitating easier ion diffusion rates and enhanced faradaic reactions. The obtained specific capacitance of the thermally exfoliated carbon black is as high as 246.49 Fg?1 in a three-electrode system and 82.85 F/g in a two-electrode setup, owing to an energy density of 5.63 Whkg?1 and a power density of 189.75 Wkg?1. It has also exhibited excellent cyclic stability and capacitance retention up to 4000 cycles. The equivalent series resistance is found to decrease from 5.67 to 4.96 ? making the material conductive. As a result, the electrochemical properties of carbon black can be enhanced by tuning the oxygen functional groups, making it a promising supercapacitive material. Graphical Abstract: (Figure presented.). Qatar University and Springer Nature Switzerland AG 2024. -
Effect of functionalization on the energy storage performance of super capacitors derived from wood charcoal
The electrochemical performance of wood charcoal is investigated with respect to the disorders in the system after subjecting to oxidation and exfoliation conditions. The Cyclic voltammetry and galvanostatic charge discharge curves indicate an improvement in the electrochemical behavior, resulting in a marginal increase in the specific capacitance values at higher exfoliation temperatures. The improvement is predominantly due to the change in the structural disorder in the system accompanied by the incorporation of oxygen functional groups which act as electrochemical active species. The exfoliation of wood charcoal at 160 and 200C yield a specific capacitance of 6.23 and 12.24 F/g at a current density of 0.01 A/g. The ESR values representing the overall resistance of the system are observed to be 6.07 ? for 200C as opposed to 10.41 ? of the bare material, making the material more conducting. The drastic change in the structural morphology along with the optimal amount of oxygen functional groups can be the reason for this behavior. The acquired results offer useful information for investigating the possibilities of fabricating supercapacitors with wood charcoal by tuning the defects of the system. 2024 American Institute of Chemical Engineers. -
Crumpled and porous graphene for supercapacitor applications: a short review
Research on Graphene and its importance in the field of energy conversion and storage devices such as fuel cells, batteries, supercapacitors and solar cells has gained momentum recently. It is studied to be the most suitable electrode material for enhanced performance of supercapacitors in terms of chargedischarge cycles, specific capacitance, high power and energy densities and so on, specifically due to its high conductivity and large theoretical surface area. Unfortunately, it posits lot of challenges due to its irreversible stacking between the individual sheets resulting in the decrease in the Specific Surface Area (SSA) compared to the theoretically reported values. Numerous studies have been carried out to prevent this stacking in order to increase the surface area, thereby being a more suitable material for the manufacture of electrodes for supercapacitors as its capacitance greatly depends on the electrode material. To solve this problem, the conversion of two-dimensional graphene sheets to three-dimensional crumpled graphene structure has been verified to be the most effective approach. The study of crumpled graphene has been one of the recent trends in the field of energy storage applications in consumer electronics and hybrid vehicles as the process of crumpling can be controlled to suit the prospective device applications. 2021, Korean Carbon Society. -
Augmentation of the energy storage potential by harnessing the defects of charcoal for supercapacitor application
The depletion of fossil fuel reserves coupled with an avalanche in the global energy demand has driven the need for developing facile techniques for energy storage devices to a large extent. Supercapacitors, has emerged as one of the most promising energy storage devices to address the demands of providing high energy density, quick charge discharge cycles and long cyclic stability. Although carbon based materials play an imperative role in the fabrication of electrode material of this device, the inherent defects are known to hinder the performance of the system. Even so, these defects can be engineered in a way to improve its overall functionality. The present work reports the tuning of the inherent defects of wood charcoal by surface functionalisation and doping via thermal annealing in order to incorporate substitutional impurities such as Nitrogen and Sulfur resulting in the improvement of the surface area and porosity of the system. The specific surface area of the system is observed to increase significantly from 4.2 m2/g of the bare material to 411.19 m2/g and 865.36 m2/g with the addition of Nitrogen and Sulfur respectively at a pyrolysis temperature of 900 C. Furthermore, the incorporation of Nitrogen exhibits a remarkable specific capacitance of 567 F/g and 193.24 F/g, and the addition of Sulfur exhibits 644 F/g and 255.1 F/g in the three-electrode and two-electrode systems respectively at a current density of 1 A/g. They also exhibit an energy density of 26.83 Whkg?1 and 17.36 Whkg?1 respectively with a capacitance retention of 88.5 % and 86.1 % for 5000 cycles. 2024 Elsevier Ltd -
Disorders in graphene: types, effects and control techniquesa review
The development of graphene and graphene-like materials has been a breakthrough in the field of nanotechnology for its exceptional properties. It exhibits extraordinary properties owing to its unique, regular arrangement of carbon atoms in it. However, graphene is usually modified for specific applications, by introducing disorder in the system. Since disorders are ubiquitous during the synthesis of graphene and graphene-like materials, it is best to exploit the defects for tuning its exceptional properties for suitable device applications. Like in any material, the disorder can drastically affect the properties, and hence they are deliberately incorporated into the material. In this review, we discuss topics related to the creation and configuration of disorders in graphene such as corrugations, topological defects, vacancies, adatoms and sp3-defects. The effects of these disorders on the electrical, thermal, chemical and mechanical properties of graphene are analysed subsequently. Finally, we review earlier works on the modulation of structural defects in graphene for specific applications. 2021, Korean Carbon Society. -
Drivers of Customer Retention: An Introspection Into Indian Retail Customers
There is a wide variety of choices for the modern retail customer including multiple retail formats. The success of the retail establishments has a great reliance of customer retention, which is an essential attribute to achieve profitability. This study takes in to consideration to extract the factors responsible for customer retention which in turn assists in increasing the customer base. The prime objective of the study is to ascertain the influence of customer satisfaction, switching costs and customer loyalty on customer retention. Whereas, the second one is to explore the effect of demographic factors on customer retention. The sample size of this study was 600 respondents who were chosen for the full-fledged study. The statistical techniques used for final analysis were structural equation modelling and regression. The findings subsequent to the statistical analysis and interpretation concluded that customer loyalty, customer satisfaction and switching cost have the strongest effect on customer retention in retails. Customer satisfaction alone is not every time an indicator of customer loyalty. A loyal customer will spread positive word of mouth to other prospective customers about the retail. Occupation of respondent has a major influence on customer retention dimensions. 2021 Management Development Institute. -
Women entrepreneurs vs. women employees: a comparative study of personality traits and success factors of women in India
In the current study, the researchers evaluate the relationship between personality traits, as defined by the Big Five personality traits, and success factors of women: as entrepreneurs and employees. The findings are based on data collected from 100 women employees and 100 women entrepreneurs. Data was collected using structured questionnaires and analysed using IBM SPSS. The findings suggest that there are statistically significant differences between women entrepreneurs and women employees on certain dimensions of personality. The evaluation of the relationship between the personality traits and success factors revealed that in the case of entrepreneurs, personality traits were significant in predicting success. As nations work to improve gender ratios in the labour force and as the number of women entrepreneurs grows, a better understanding of what constitutes success and the factors that could influence success are critical in supporting female participation in the economy, as entrepreneurs and employees. Copyright 2024 Inderscience Enterprises Ltd. -
Metalsemiconductormetal visible photodetector based on Al-doped (Cd:Zn)S nano thin films by hydrothermal synthesis
High quality undoped and Al-doped nanocrystalline (Cd:Zn)S films [CZS and ACZS] were deposited on glass substrates by hydrothermal assisted chemical bath deposition. The Al concentration was varied from 0.5 mol.% to 2 mol.% in steps of 0.5 mol.% replacing cadmium while keeping other deposition parameters constant. XRD, SEM, and EDX were used to observe crystallinity, morphology and composition of the as prepared samples. X-ray diffraction revealed the hexagonal phase of CZS films with prominent orientation along the (002) plane. XPS analysis was used to confirm the doping concentration of Al in to CZS lattice. Repeatable photoresponse was recorded under 100 s cycle light-on and light-off conditions. 1 mol.% Al doped film being optimised as good photoconductor; a photodetector was fabricated with Ag/ACZS/Ag device structure. The ACZS photodetector exhibits similar time response, good photocurrent reproducibility and a sharp photoresponse at blue radiation with high photo-dark current ratio of 95. The device exhibits peak responsivity of 3.48 mA W?1 and detectivity of 1.26 1011 Jones at 470 nm. These properties suggest that the ACZS photodetector holds great potential for application in high-performance visible photodetectors, especially in the blue region. 2021 Elsevier GmbH