•DFT has been performed to study the spin interactions on electronic structures, magnetic moments, and optical properties of CoFe2O4.•High DOS at Fermi level manifests strong electron-electron ...interactions.•The calculated total spin magnetic moments 6.98μB is a results of high spin polarization.•The highly spin polarized CoFe2O4 material can be used as spintronic devices as well as optical reflector.
This report demonstrates the structural, electronic, magnetic, elastic, and optical properties of spinel CoFe2O4 using generalized gradient approximation (GGA). Both the spin and non-spin polarized density functional theory (DFT) have been used to study the influence of spin interactions on electronic structures, spin magnetic moments, and optical properties. The calculated magnetic moments of CoFe2O4 from spin density of states are 6.98 μB per formula unit. The Fe and Co ions prefer high spin orientations owing to the cationic polarization because of crystal field strength and intra-atomic exchange interactions, which induces large spin magnetic moments. The high values of spin magnetic moments confirm strong spin orbit coupling due to strong electron-electron interactions and can be a promising for spintronic application. Moreover, the calculated high reflectivity of CoFe2O4 material (~100%) in the Infrared-Visible-Ultraviolet region up to ~30 eV, which suggesting that the CoFe2O4 can also be a good candidate for solar reflector.
Despite being simpler, cheaper, and less energy-intensive than other desalination processes, solar stills have apparent shortcomings in terms of productivity. Such a limitation has been prompting the ...researchers to strive in upgrading this renewable-driven technology through innovative add-ons. With a similar goal, the present study looks into the combined effect of unique modifications of internal sidewall reflector (ISR), hollow circular fin (HCF), phase change material (PCM), and nanoparticle mixed PCM (nano-PCM) on the thermodynamic performance of double slope solar stills. One passive (conventional) and one active (modified) double slope stills are constructed to experimentally evaluate and compare selected energy, exergy, exergo-economic, environmental, and sustainability metrics. The results indicate that the cumulative action of ISR, HCF, and PCM (Case II) leads up to 51.8% augmented productivity compared to the conventional case (Case I) where there is an additional increase of 21.5% when PCM is mixed with nanoparticles (Case III). While both the modified cases experience sizeable improvements in energy and exergy efficiencies compared to the conventional one, nano-PCM, in particular, boosts these quantities by 20.1% and 25%, respectively. Furthermore, nano-PCM induces around 2% additional cost-saving per unit of water production while mitigating a maximum CO2 emission of 3.65 ton. In addition to these assessments, the exergetic sustainability of the stills is discussed using vital indicators such as waste exergy ratio, improvement potential, sustainability index, etc. For the three experimental cases, the values of improvement potential, environmental effect factor, and sustainability index are attained within the ranges of 1374–1469 kWh/yr, 0.529–1.137, and 1.006–1.016, respectively.
To develop a spore inactivation strategy, the effect of 15-min hydrostatic pressure treatments (550 and 650 MPa) at 55 and 75 °C in citric acid buffer (4.75 and 6.5 pH) on spores of 5 isolates of ...Clostridium perfringens type A carrying the gene that encodes the C. perfringens enterotoxin (cpe) on the chromosome (C-cpe), 4 isolates carrying the cpe gene on a plasmid (P-cpe), and 2 strains of C. sporogenes were investigated. Treatments at 650 MPa, 75 °C and pH 6.5 were moderately effective against spores of P-cpe (approximately 3.7 decimal reduction, DR) and C. sporogenes (approximately 2.1 DR) but not for C-cpe (approximately 1.0 DR) spores. Treatments at pH 4.75 were moderately effective against spores of P-cpe (approximately 3.2 DR) and C. sporogenes (approximately 2.5 DR) but not of C-cpe (approximately 1.2 DR) when combined with 550 MPa at 75 °C. However, when pressure was raised to 650 MPa under the same conditions, high inactivation of P-cpe (approximately 5.1 DR) and C. sporogenes (approximately 5.8 DR) spores and moderate inactivation of C-cpe (approximately 2.8 DR) spores were observed. Further advances in high-pressure treatment strategies to inactivate spores of cpe-positive C. perfringens type A and C. sporogenes more efficiently are needed.
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•A high yield vacuum-type pyramid-solar-still was investigated experimentally.•Hourly and daily productivity enhanced by 22.3 % and 63 % respectively.•Distillation and exergy ...efficiencies were improved by 28.7 % and 22.4 % respectively.•Incorporation of PCM with vacuum condition outperformed conventional solar stills.
In this study, a solar-energy-driven high performance water purification system is designed, fabricated, and examined, which may be useful for remote areas with limited access to grid electricity and underground freshwater. This research aims to enhance the performance of a conventional solar still (double-slope type) by creating vacuum inside the chamber and using paraffin wax (PCM) as energy storage material. The performance of the modified solar still (SS) is investigated and compared with the conventional solar still (CSS) in terms of productivity, distillation efficiency, and exergy efficiency. The performance analyses show that the hourly productivity and daily cumulative productivity are increased by 22.33 % and 63 % (from 5.46 L/m2 to 7.03 L/m2) respectively for the modified still compared to the conventional still. Nearly 28.72 % distillation efficiency and 22.43 % exergy efficiency enhancement are recorded for the modified system compared to the conventional system. This study also reveals that the thermal performance of the modified system is significantly improved under vacuum condition and using paraffin wax as heat storage material, which enables the still to operate at low solar intensities. The economic analysis shows that the cost of freshwater produced per liter in the modified SS is 41.4 % less than that of the conventional SS.
Cadmium oxide (CdO) and yttrium (Y) doped CdO (Y: CdO) thin films have been prepared onto glass substrate at temperature 300 °C by spray pyrolysis technique. The effects of yttrium (Y) doping on the ...structural, morphology, optical and electrical properties were studied systematically. The X-ray diffraction (XRD) study confirms that CdO films are polycrystalline in nature with cubic structure having lattice parameter of 0.4658 nm. Surface topographic and nano-structural analysis indicates cluster grain size and porosity decreased substantially with increase of yttrium (Y) content in CdO films. The optical transmittance exhibits excellent optical transparency, with an average transmittance of >70% in the visible range for 2 to 4% yttrium (Y) doping. The optical band gap widens in Y: CdO film from 2.24 to 2.62 eV through Burstein- Moss shift. Hall measurement confirms that material is of n type with a minimum resistivity of 4.7 × 10−4 Ω-cm with carrier concentration of 4.2 × 1021 cm−3 were achieved for 2% yttrium (Y) doping.
BaTiO3 exhibits promising photocatalytic characteristics and has the potential to be employed in photocatalytic water splitting and pollutant degradation. Herein, we have investigated the structural, ...electronic, and optical properties of BaTiO3 in the framework of density functional theory (DFT). The obtained results are found to be consistent with theoretical results. However, using hybrid HSE06 functional, the calculated bandgap values are 3.254, 3.894, 3.694, 3.519, and 3.388 eV corresponding to cubic, rhombohedral, orthorhombic, tetragonal, and hexagonal phase of BaTiO3 polymorphs. This is the first time a DFT calculation touched over the experimental bandgap values of BaTiO3 polymorphs.
Electronic band structure analysis revealed that all the BaTiO3 polymorphs exhibit semiconducting character with indirect bandgap except hexagonal structure which possesses direct bandgap. The density of states (DOS), Mulliken bond analysis and charge density distribution indicates considerable hybridization between O-2p and Ti-3d states caused to the formation of upper valence band (VB) and lower conduction band (CB). The wide bandgap and suitable redox potential of BaTiO3 polymorphs will be effective for water splitting as well as breakdown organic contaminants under UV–vis irradiation. The lower electron effective mass of the polymorphs indicates higher electrical conductivity. The energy dependent optical parameters show close agreement with the underlying electronic band structure. The high absorptivity, lower reflectivity and optical anisotropy (orthorhombic and tetragonal) of the polymorphs suggested that these could be a potential candidate for UV based optical device applications as well as to design wave guides, dielectric condensers and optical display devices.
Employing the solid-state reaction route, good quality polycrystalline sample NiV
2
O
6
is prepared that has effective application in rechargeable Li-ion batteries. The raw materials NiO and V
2
O
5
...(purity >99%) were used for the fabrication of NiV
2
O
6
. The phase formation and thermal stability of this sample were measured by thermogravimetric analyzer. The micro-structural feature of this sample was measured by scanning electron microscopy (SEM). The SEM images ensured that the product NiV
2
O
6
is very uniform and well-separated and consists of large grain size of about 1–5 μm. The crystal structure and bonding characteristics of NiV
2
O
6
were obtained by XRD diffractometer and FTIR spectroscopy. The X-ray diffraction data revealed the triclinic structure of NiV
2
O
6
with space group P-1 and lattice parameters:
a
= 7.162 Å,
b
= 8.816 Å,
c
= 4.789 Å, and axial angles α = 90.13°, β = 93.78°, and γ = 101.72°. The temperature-dependent electrical resistivity of NiV
2
O
6
was measured by two-probe method which ensured the semiconducting nature of this phase. The electronic and optical properties were investigated by impedance analyzer and UV-Visible spectrophotometer. The calculated optical band gap of NiV
2
O
6
is found to be 2.38 eV.
A hard magnetic system of SrFe
O
nanomaterial was modified according to the composition of Sr
Gd
Fe
Cu
O
with
= 0.0, 0.30, and 0.60 using the sol-gel technique. The structures of the samples were ...evaluated using X-ray diffraction (XRD) along with Rietveld refinement, and an M-type hexaferrite with a hexagonal structure was confirmed with a trace amount of the α-Fe
O
phase. In addition, transmission electron microscopy (TEM) analysis revealed polycrystalline nanoplates in all samples. Furthermore, the bond structures of the octahedral and tetrahedral sites along with the thermodynamic properties of these ferrites were extracted from the FTIR spectra at room temperature. The Debye temperature (
) decreased from 755.9 K to 749.3 K due to the co-substitution of Gd
at Sr
and Cu
at Fe
. The magnetic hysteresis (
-
) measurements revealed that the coercivity decreased from 5.3 kOe to 1.5 kOe along with the highest magnetization saturation (
) of 65.2 emu g
for the composition Sr
Gd
Fe
Cu
O
, which is suitable for industrial application. The effect of local crystalline anisotropy in magnetization was explored using the law of approach to saturation (LAS). Finally, thermo-magnetization was recorded in the range from 400 K to 5 K for cooling under zero field and in the presence of a 100 Oe field, and magnetic transitions were tracked due to the introduction of the foreign atoms of Gd and Cu into SrFe
O
.
In the present study, the heat transfer performance and friction factor characteristics in a circular tube fitted with twisted wire brush inserts were investigated experimentally. The twisted wire ...brush inserts were fabricated with four different twisted wire densities of 100, 150, 200, and 250 wires per centimeter by winding a 1mm diameter of the copper wire over a 5mm diameter of two twisted iron core-rods. Heat transfer and friction factor data in tubes were examined for Reynolds number ranging from 7,200 to 50,200. The results indicated that the presence of twisted wire brush inserts led to a large effect on the enhancement of heat transfer with corresponding increase in friction factor over the plain tube. The Nusselt number and friction factor of using the twisted wire brush inserts were found to be increased up to 2.15 and 2.0 times, respectively, than those over the plain tube values. Furthermore, the heat transfer performance was evaluated to assess the real benefits of using those type of inserts and the performance was achieved 1.85 times higher compared to the plain tube based on the constant blower power. Finally, correlations were developed based on the data generated from this work to predict the heat transfer, friction factor, and thermal performance factor for turbulent flow through a circular tube fitted with the twisted wire brush inserts in terms of wire density (y), Reynolds number (Re), and Prandtl number (Pr).
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