In the present study, electrochemical impedance analysis in terms of electrical conductivity, dielectric permittivity, and electrical modulus has been carried out of prepared sodium ion-conducting ...nanocomposite gel polymer electrolyte. To study ion conduction behavior, frequency-dependent AC conductivity has also been analyzed. Dielectric constant (
ε′
) and dielectric loss (
ε′′
) as a function of frequency with different nanofiller SiO
2
concentrations as well as at different temperatures ranging from 303 to 333 K have been discussed. The low-frequency region showed high values of dielectric constant due to polarization at the electrode–electrolyte interface. Frequency-dependent real (
M′
) and imaginary part (
M′′
) of modulus reveal large capacitance associated with it at lower frequency whereas dispersion (conductivity relaxation) at a higher frequency. The tangent loss (tan
δ
) of the electrolyte systems has been determined for different frequencies and concentrations of fumed silica nanoparticles. The high conducting nanocomposite gel polymer membrane exhibited an electrochemical stability window of ≈ 3.3 V which is sufficient to apply this material as a separator for electrochemical device application. The conductivity, dielectric, modulus, and electrochemical stability studies reveal that sodium ion-conducting nanocomposite gel polymer electrolytes offer good electrochemical properties and are suitable for application in any electrochemical/power conversion device. The optimized flexible nanocomposite gel polymer electrolyte films have been used in a prototype sodium battery, which shows a stable open-circuit potential of ~ 2.1 V and a significant first specific discharge capacity of ~ 500 mAh g
−1
at a drain current of 14 mA g
−1
.
•Microwave-assisted hydrothermal synthesis of NiO nanostructures with Li-doping at low temperature.•p-Type dye-sensitized solar cell based on NiO photocathode.•Study on the effect of Li doping ...concentration on the cell performance.
Nickel oxide (NiO) nanostructures are synthesized using a microwave-assisted hydrothermal method. The hydrothermal bath has a solution of nickel salt mixed with precipitating agent. During the synthesis the microwave temperature, the concentration of nickel salt and precipitating agent along with the pH of the reaction solutions are changed and different morphologies of nickel oxide are obtained. The resulting nickel oxide nanostructures are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller method and X-ray photoelectron spectroscopy. Thus formed NiO has been used as a photocathode in dye-sensitized solar cell. Lithium doped NiO showed better IPCE as well as solar to electrical conversion efficiency than the undoped NiO.
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► CeO2–CaO nanocomposite oxides are synthesized by the amorphous citrate method. ► The composite oxide contains a substitutional solid solution of the type Ce1−xCaxO2−x. ► Presence of ...low coordinated surface Ce4+ sites is seen in the nanocomposite oxide. ► The particle size of the mixed oxide phase is in the range of 5–25nm. ► CeO2–CaO nanocomposite is a highly efficient catalyst for the synthesis of 2-amino-2-chromenes.
A series of CeO2–CaO nanocomposite oxides were synthesized by the amorphous citrate method and characterized by TGA, XRD, UV–Vis-DRS, SEM and TEM experimental techniques. The XRD analysis indicated the presence of a substitutional type solid solution for ceria rich composite oxides whereas for the calcium oxide rich composite oxides, the presence of crystalline CaO was observed along with the solid solution phase. Fourier line profile analysis of the broadened X-ray diffraction profiles revealed the presence of small nanocrystallites of the mixed oxides with size in the range of 5–25nm. UV–Vis-DRS study of the composite oxide showed well dispersion of the ceria in the CaO matrix. The characteristic reflections from the low coordinated surface Ce4+ ions were observed in the UV study along with a blue shift in the absorption edge for samples containing up to 20mol% ceria. The direct band gaps calculated from the UV spectra were found to be in the range of 3.45–3.66eV. The composite oxide materials were found to be porous and spongy in nature observed from the SEM analysis. TEM study of the CeO2(20%)–CaO material indicated the presence of well dispersed mixed oxide nanoparticles in a continuous CaO matrix. The Ce–Ca–O nanocomposite oxides were used as an environmentally benign catalyst for the multicomponent one pot synthesis of 2-amino-2-chromenes by multicomponent condensation of aryl aldehydes, α-naphthol and malononitrile in aqueous media. The nanocomposite oxides were found to be highly efficient for the synthesis of structurally diverse aminochromenes with excellent yield and purity.
Magnesia stabilized zirconia-alumina composite were processed by auto-combustion method followed by solid-state sintering. Tetragonal zirconia with orthorhombic alumina phase has been ensured from ...XRD patterns and from Raman spectra. The optical band gap energy for 2%, 4% and 6% magnesium oxide substituted zirconia-alumina composites are 4.91, 5.03 and 3.48 eV, respectively. The dielectric behavior between the frequency range of 1 kHz-1 MHz shows frequency independent nature of dielectric constant with low loss tangent at various temperatures. The non-Debye type and grain-grain boundary effects were confirmed from Nyquist plot. Both PTCR and NTCR behavior were observed from AC conductivity study.
Of late researchers are putting stress on the active utilisation of solar energy to promote the use of renewable energy. Solar water heating is considered as an environmental friendly technique to ...harness the solar energy for heating application. In this research, the effects of using Phase Change Materials (PCM) doped CuO nanocomposite as storage medium on the performance of a solar water heater have been experimentally investigated. By varying the wt% of nano CuO, the gap between the absorber plate and the glazing, the effect on the outlet temperature is examined. The maximum temperature of outlet water has been recorded as 60.1 °C using nano CuO-PCM composite over base PCM under similar conditions. As the mass fraction/wt% of nano CuO increases in PCM, the thermal conductivity, heat flow and thermal efficiency increases. It has been found that better results have been achieved while using 1.00 wt% CuO-PCM nanocomposite. The thermal conductivity of pure wax is found to be about 0.21 W/mK while 1.00 wt% PCM CuO- nanocomposite has thermal conductivity of 0.36 W/mK. It is noticed that there is an appreciable increment in the efficiency of solar water heater under the variation of three observed parameters i.e. time, temperature and solar intensity.
•Nano CuO particles synthesis via economically viable and eco-friendly process.•Band gap energy of PCM increases due to the presence of nanoparticles.•Heat transfer enhancement by nanoparticles.•Thermal efficiency increment as solar intensity and temperature difference increases.
Abstract
For solar system objects, ultraviolet spectroscopy has been critical in identifying sources of stratospheric heating and measuring the abundances of a variety of hydrocarbon and ...sulfur-bearing species, produced via photochemical mechanisms, as well as oxygen and ozone. To date, fewer than 20 exoplanets have been probed in this critical wavelength range (0.2–0.4
μ
m). Here we use data from Hubble’s newly implemented WFC3 UVIS G280 grism to probe the atmosphere of the hot Jupiter HAT-P-41b in the ultraviolet through optical in combination with observations at infrared wavelengths. We analyze and interpret HAT-P-41b’s 0.2–5.0
μ
m transmission spectrum using a broad range of methodologies including multiple treatments of data systematics as well as comparisons with atmospheric forward, cloud microphysical, and multiple atmospheric retrieval models. Although some analysis and interpretation methods favor the presence of clouds or potentially a combination of Na, VO, AlO, and CrH to explain the ultraviolet through optical portions of HAT-P-41b’s transmission spectrum, we find that the presence of a significant H
−
opacity provides the most robust explanation. We obtain a constraint for the abundance of H
−
,
, in HAT-P-41b’s atmosphere, which is several orders of magnitude larger than predictions from equilibrium chemistry for a ∼1700–1950 K hot Jupiter. We show that a combination of photochemical and collisional processes on hot hydrogen-dominated exoplanets can readily supply the necessary amount of H
−
and suggest that such processes are at work in HAT-P-41b and the atmospheres of many other hot Jupiters.
This paper reports the comparative studies on polymer gel electrolytes (PGEs) comprising liquid electrolytes of the triflate salts of Li, Na, and Mg in tetraethylene glycol dimethyl ether (TEGDME) ...solvent and poly(vinylidene fluoride-hexafluoropropylene) and poly(vinylpyrroliddone), i.e., PVdF(HFP)/PVP polymer blend matrix. The effect of different cations is investigated using various structural, thermal, and electrochemical techniques. The ionic conductivity and the ion-transport behavior are investigated using electrochemical impedance spectroscopy (EIS) over wide range of frequency. The XRD studies indicate the prominent structural variation after the immobilization of Li, Na, and Mg triflate salts in the PVdF(HFP)/PVP/TEGDME matrix. The Li
+
ion conducting PGE composition displays the maximum room temperature ionic conductivity of ~ 6.5 × 10
−3
S cm
−1
. Further, it exhibits a high dielectric constant value and superior ion-dynamics as compared to Na
+
and Mg
2+
based electrolytes. The PGEs display translational ion-dynamics and conductivity relaxation clubbed with polarizing effects and long-range mobility/migration of the cations (Na
+
, Mg
2+
, Li
+
). The morphological and structural studies reveal that Li
+
ion conducting PGE offers a porous structure with smooth surface facilitating faster ionic motion. The PGEs possess considerable electrochemical stability window (≥ 4.0 V) and thermal stability, which prove them worthy for developing ion-batteries, super-capacitors and other next-generation electrochemical devices.
•BMImCF3SO3 ionic liquid based TiO2 dispersed porous PVDF-HFP electrolyte membrane.•Flexible electrolyte membranes prepared by phase inversion technique.•Enhanced ionic conductivity and Na+ ...transference number on dispersion of TiO2.•Proto-type sodium battery utilizing optimized electrolyte membrane.
A nanocomposite gel polymer electrolyte system comprising porous membrane of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/TiO2 immobilizing a liquid electrolyte of sodium trifluoromethanesulfonate (NaCF3SO3) in 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMImCF3SO3) ionic liquid is reported in the paper. The porous gel polymer electrolyte membranes are prepared by phase-inversion technique. The electrolyte membranes are characterized by various physical and electrochemical techniques. The TiO2 nanoparticles display interaction with the anion (CF3SO3−) of the liquid electrolyte and enhance amorphicity in the polymer network. The optimized membrane displays maximum room temperature ionic conductivity as ~0.4 mS cm−1 with improved electrochemical stability window of ~4.3 V and Na+ ion transport number as ~0.27. A proto-type sodium battery using the optimized membrane is fabricated and characterized. The battery delivers a stable open circuit potential of ~2.2 V and shows a discharge capacity ~200 mA h g−1 at 25 mA g−1 drain current.
ABSTRACT Neuroblastomas are the most common extracranial solid tumor in the pediatric age group (~8%–10% of childhood neoplasms). Most cases of intracranial neuroblastomas occur due to metastasis ...from some primary extracranial sites and are known as secondary neuroblastomas. However, the occurrence of primary central nervous system neuroblastomas (PCN-NB) is very rare, and only a few cases and case series have been reported in the literature. PCN-NB is mainly an intra-axial pathology, and extra-axial involvement is mainly due to metastasis from some extracranial primary site with involvement of the skull bone. Herein we report a case of a 23-year-old female having a large extra-axial space-occupying lesion in the right frontal region that was mimicking a meningioma, and surprisingly the histopathology was suggestive of a supratentorial neuroblastoma. A right frontal craniotomy was made, and Simpson’s grade 1 excision of the tumor was done. The excised tissue was sent for histopathological examination. PCN-NB located extra-axially are extremely rare to occur. Due to inconsistent radiological imaging, it becomes very difficult to diagnose these tumors preoperatively, and these should be kept in mind as one of the differential diagnoses of extra-axial intracranial space-occupying lesions. Histopathological examination is crucial in diagnosing the intracranial neuroblastomas.
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