12 research outputs found
“A legacy of troubles. Bengal Partition as long-lasting narration”
No full textThis essays analyses Indian Partition Literature, focusing on the Eastern border and the novel East/West by the Bengali author Gangopadhyay
Multi-technique photoelectron spectrometer for micro-area spectroscopy and imaging
No full textIn this note we present the new multipurpose photoelectron spectroscopy facility installed recently at the CSIR-Central Glass and Ceramic Research Institute, Kolkata. Apart from the possibility of performing conventional X-ray and ultraviolet photoemission spectroscopic measurements, this instrument is also equipped with the necessary sources facilitating the performance of macro- as well as micro-area spectroscopy at varying temperatures along with the possibility of X-ray beam-induced secondary electron and chemical state imaging. We present here the details of the instrument along with some experimental results from various samples assessing the system performance
Localization of electrons in internal frame
No full textLocalization of electrons in the internal frame of reference is well established in one dimension in the presence and absence of Coulomb interaction. We start from quasi-one-dimensional (Q1D) ring and show the possibility of such a transition by going to a regime where it can be shown for electrons that just interact via Fermi statistics. We then give a proof that when the Q1D ring is made infinitely wide, then there will be such a localization even when Coulomb interaction is included. Finally, we also comment on dimensions greater than two
Removal of trivalent metal ions from aqueous solution via cross-flow ultrafiltration system using zeolite membranes
No full textThis study aimed to assess the performance of three zeolite membranes in the removal of trivalent metal ions from aqueous solution using a cross-flow mode of operation. Three types of zeolite membrane, MCM-41, MCM-48 and FAU, were prepared on a low-cost, circular ceramic support by hydrothermal treatment. The three zeolite membranes were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and contact angle measurements. The XRD results confirmed the formation of zeolites. The deposition of zeolite on the ceramic support and hydrophilicity of zeolite membranes were monitored by FESEM and contact angle measurement, respectively. The pore size of the MCM-41, MCM-48 and FAU membrane was found to be 0.173 μm, 0.142 μm, and 0.153 μm, respectively, which was lower than that of the support (1.0 μm). The fabricated zeolite membranes were used to investigate the separation behavior of trivalent metal ions (Al3+ and Fe3+) from aqueous solution at various applied pressures. It was observed that an increase of applied pressure leads to a slight decrease in the removal efficiency. Among the various zeolite membranes, the FAU membrane showed the maximum rejection of 88% and 83% for Fe3+ and Al3+ separation, respectively
Effect of mechanical milling on the structural and dielectric properties of BaTiO3 powders
No full textBarium titanate (BaTiO3) is a well-known ferroelectric material and widely used in electronic industries for the multi-layer ceramic capacitor. In this reported work, commercially available tetragonal BaTiO3 (BT) powders were taken to study the size effect on the structural and dielectric properties of the BT ceramics during high-energy ball milling (0-110 h). The same perovskite when kept under a normal atmospheric condition after milling shows gradual increase of additional crystalline phase that occurred because of the absorption of atmospheric CO2 gas, which is characterised as orthorhombic BaCO3. The milled BT samples were characterised by X-ray diffraction and small-angle X-ray scattering and a dielectric analyser. The purpose of this work was to study how the dielectric property of nanoBT ceramics varies with reduction of particle size, structural changes and the absorption of carbon by these nanopowders. It was observed that the dielectric constant of the BT powders increases with particle size reduction during milling. The dielectric behaviour of the BT ceramics significantly changes with polymorphic phase transformation in nanocrystalline BT at different stages of milling. The capacitance of nanoBT powders is significantly changed with the absorption of carbon by the nanoBT powders in a humid atmosphere
Activating ZnO nanorods photoanodes in visible light by CdS surface sensitiser
Get PDFThin films of c-axis aligned uniform ZnO nanorods (NRs) were fabricated on to fluorine-doped tin oxide-coated soda lime glass substrate by a two-step chemical route. Thereafter ZnO NRs/CdS core shell structures were successfully synthesised by depositing CdS layer on top of vertically aligned ZnO NRs using less hazardous nanocrystal layer deposition technique. The presence of CdS in ZnO NRs/CdS core shell structures was confirmed by energy dispersive X-ray analysis. Examination of structure and morphology of the fabricated films by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) revealed that both films have one-dimensional hexagonal wurtzite structure. Optical properties evaluated from ultraviolet–visible and photoluminescence spectra demonstrated better photo response of ZnO NRs/CdS core shell structure with respect to bare ZnO NR structure. Optical to chemical conversion efficiency of ZnO NRs/CdS photoanode was found to be ∼1.75 times higher than bare ZnO NRs photoanode in photo electrochemical water splitting under visible light
Effects of Mg% on open circuit voltage and short circuit current density of Zn1-xMgxO/Cu2O heterojunction thin film solar cells, processed using electrochemical deposition and spin coating
No full textZn1-xMgxO/Cu2O/Ag solar cells were fabricated upon fluorine doped tin oxide coated soda lime glass substrate with varying percentage of Mg mol% doping in zinc oxide (ZnO) layer. Short circuit current density & open circuit voltages of the fabricated cells were investigated. Optimum doping with Mg improved the transparency of ZnO layer which helped in increasing the short circuit current density of solar cells. An enhancement of open circuit voltage was observed with increase in x, which was investigated using X-ray photoelectron spectroscopy and the results revealed that with increase in x, there was a decrease in conduction band offset between Zn1-xMgxO and cuprous oxide layers. From UV-Visible transmittance spectra, it was observed that with Mg doping in ZnO nanostructure, optical losses were reduced which resulted in increase in Short circuit current density. The objective of this study was to investigate and develop a technology for fabrication of solar cells that is both cost effective and easy to produce
Low-temperature synthesis of strain sensor based on flexible ZnO nanowire-cellulose paper composite
No full textZnO nanowire was synthesised chemically at low temperature on a flexible three-dimensional and porous cellulose paper. The morphology and crystallography of the composite was characterised by field emission scanning electron microscope and X-ray diffraction. Performance of the developed ZnO nanowire-cellulose paper composite as strain sensor demonstrated good stability, high gauge factor and good repeatability. The results indicate the possible use of this sensitive and robust strain sensor in the fields of biomedical sciences, MEMS devices and structural health monitoring and other fields
Biochar potentially enhances maize tolerance to arsenic toxicity by improving physiological and biochemical responses to excessive arsenate
No full text© 2023, The Author(s). cc-byMetalloid pollution, including arsenic poisoning, is a serious environmental issue, plaguing plant productivity and quality of life worldwide. Biochar, a carbon-rich material, has been known to alleviate the negative effects of environmental pollutants on plants. However, the specific role of biochar in mitigating arsenic stress in maize remains relatively unexplored. Here, we elucidated the functions of biochar in improving maize growth under the elevated level of sodium arsenate (Na2AsO4, AsV). Maize plants were grown in pot-soils amended with two doses of biochar (2.5% (B1) and 5.0% (B2) biochar Kg−1 of soil) for 5 days, followed by exposure to Na2AsO4 ('B1 + AsV'and 'B2 + AsV') for 9 days. Maize plants exposed to AsV only accumulated substantial amount of arsenic in both roots and leaves, triggering severe phytotoxic effects, including stunted growth, leaf-yellowing, chlorosis, reduced photosynthesis, and nutritional imbalance, when compared with control plants. Contrariwise, biochar addition improved the phenotype and growth of AsV-stressed maize plants by reducing root-to-leaf AsV translocation (by 46.56 and 57.46% in ‘B1 + AsV’ and ‘B2 + AsV’ plants), improving gas-exchange attributes, and elevating chlorophylls and mineral levels beyond AsV-stressed plants. Biochar pretreatment also substantially counteracted AsV-induced oxidative stress by lowering reactive oxygen species accumulation, lipoxygenase activity, malondialdehyde level, and electrolyte leakage. Less oxidative stress in ‘B1 + AsV’ and ‘B2 + AsV’ plants likely supported by a strong antioxidant system powered by biochar-mediated increased activities of superoxide dismutase (by 25.12 and 46.55%), catalase (51.78 and 82.82%), and glutathione S-transferase (61.48 and 153.83%), and improved flavonoid levels (41.48 and 75.37%, respectively). Furthermore, increased levels of soluble sugars and free amino acids also correlated with improved leaf relative water content, suggesting a better osmotic acclimatization mechanism in biochar-pretreated AsV-exposed plants. Overall, our findings provided mechanistic insight into how biochar facilitates maize’s active recovery from AsV-stress, implying that biochar application may be a viable technique for mitigating negative effects of arsenic in maize, and perhaps, in other important cereal crops. Graphical Abstract: [Figure not available: see fulltext.
Exploration of Diverse Interactions of l‑Methionine in Aqueous Ionic Liquid Solutions: Insights from Experimental and Theoretical Studies
No full textHere, we have investigated some physicochemical parameters
to understand
the molecular interactions by means of density (ρ) measurement,
measurement of viscosity (η), refractive index(nD) measurement, and conductance and surface tension measurements
between two significant aqueous ionic liquid solutions: benzyl trimethyl
ammonium chloride (BTMAC) and benzyl triethyl ammonium chloride (BTEAC)
in an aqueous l-methionine (amino acid) solution. The apparent
molar volume (Φv), coefficient of viscosity (B), and molar refraction (RM) have been used to analyze the molecular interaction behavior associated
in the solution at various concentrations and various temperatures.
With the help of some important equations such as the Masson equation,
the Jones–Doles equation, and the Lorentz–Lorenz equation,
very significant parameters, namely, limiting apparent molar volumes
(Φv0), coefficient of
viscosity (B), and limiting molar refraction (RM0), respectively, are obtained.
These parameters along with specific conductance (κ) and surface tension (σ) are very much helpful to reveal the
solute–solvent interactions by varying the concentration of
solute molecules and temperature in the solution. Analyses of Δμ10#, Δμ20#, TΔS20#, ΔH20#, and thermodynamic data provide
us valuable information about the interactions. We note that l-Met in 0.005 molality BTEAC ionic liquid at 308.15 K shows maximum
solute–solvent interaction, while l-Met in 0.001 molality
BTMAC aqueous solution of ionic liquid at 298.15 K shows the minimum
one. Spectroscopic techniques such as Fourier transform infrared (FTIR), 1H-NMR, and UV–vis also provide supportive information
about the interactions between the ionic liquid and l-methionine
in aqueous medium. Furthermore, adsorption energy, reduced density
gradient (RDG), and molecular electrostatic potential (MESP) maps
obtained by the application of density functional theory (DFT) have
been used to determine the type of interactions, which are concordant
with the experimental observations
