This investigation consists of results of the studies on dielectric properties and a.c. conductivity of Li
2
O-Ga
2
O
3
-SiO
2
(LGS) glass with 2.0 mol% of Cr
2
O
3
, MoO
3
, WO
3
across 0.01 Hz to ...1 MHz and 20 °C to 240 °C. Structural analysis using optical absorption and IR spectra indicated dopant ions predominantly in Cr
3+
, Mo
6+
/Mo
5+
, W
6+
states, and occupied
T
d
and
O
h
positions. Dielectric constant and conductivity were found to be the maximal for LGSMo glass, with the lowest impedance, while LGSCr glass exhibited the opposite trend. From the analysis of dipolar relaxation effects probable dipoles were identified in each glass. Studies on conductivity revealed that contribution of ionic components is very low and a substantial polaronic contribution in LGSMo glass, whereas, LGSCr glass showed a larger ionic component, specifically Li
+
ion diffusion and hence more useful material for solid-state batteries with respect to the other two glasses.
Zinc selenium phosphate glasses added with the traces of Au
2
O
3
were prepared and heat-treated. XRD, TEM, DSC, FT-IR and optical absorption (OA) spectroscopy methods were used for the structural ...assessment of these samples. Later, different dielectric parameters viz., dielectric constant (
ε′
), electric moduli (
M
), impedance (
Z
) and a.c. conductivity (
σ
ac
) were measured over wide regions of frequency (
ω
) and temperature (
T
) as functions of Au
2
O
3
concentration. Dielectric breakdown strength (DBS) of these samples was also measured at ambient conditions. The characterization studies indicated that multiple crystal grains were entrenched in the residual amorphous phase of the samples. The X-ray diffraction studies revealed that the bulk glasses consisted of Au
2
(SeO
3
)
3
crystal phase and Au
0
metallic particles (MPs). As Au
2
O
3
content was raised, the intensity of the XRD peak related to Au
3+
crystal phase indicated a growing trend, whereas that of Au
0
MPs showed a decreasing trend. The results of XPS studies revealed similar inferences. The FT-IR results pointed out an improved degree of augmentation of the glass network as the content of Au
2
O
3
was increased. Optical absorption (OA) - spectra of the glasses indicated a broad absorption band in the spectral range of 500–600 nm due to the surface plasmon resonance (SPR) of Au
0
MPs. The intensity of the band was observed to decrease as Au
2
O
3
content was increased and indicated decreasing proportion of Au
0
metallic particles in the samples. The dielectric parameters exhibited a decreasing trend, whereas the dielectric breakdown strength (DBS) and electrical impedance indicated a substantial hike due to the increasing concentration of Au
2
O
3
. Overall, the presence of Au
2
O
3
caused a significant improvement in the insulating strength of the ZnO added SeO
2
-P
2
O
5
glasses and hence such glasses may be considered as insulating layers in the display panel devices.
•Impact of HgO on dielectric properties and σac of Li2O-P2O5 glasses was explored.•ε′, σac exhibited increase with HgO upto 5 mol% w.r.t. pure sample.•Up to 5 mol% HgO ionic contribution to σac is ...predominant.•Beyond 5 mol% HgO polaronic tunneling became more significant.•Lithium phosphate glasses with 5 mol% HgO are suitable as solid electrolytes.
This study investigates the impact of HgO concentration on the dielectric properties and a.c. conductivity of the Li2O-P2O5 glass system. XRD, SEM, DSC and FT-IR spectral techniques were employed to analyze the structural variations of the samples due to the varying contents of HgO. The dielectric properties and σac were studied across wide temperature (T) and frequency (ω) ranges to understand the conduction phenomenon. The results revealed that the presence of 5 mol% HgO led to an increase in dielectric parameters and a.c. conductivity compared to those of pure sample. Variation of σac with HgO content indicated that up to 5 mol% HgO, the ionic contribution to σac was predominant, while beyond that, polaronic tunneling became more significant. Therefore, lithium phosphate glasses with 5 mol% HgO are suitable as solid electrolytes, while glasses doped with higher HgO concentrations are better suited as electrodes in ionic batteries.
•Pb3O4 mixed Li2O-SiO2:Au2O3 glasses were synthesized and characterized.•Different dielectric parameters viz., ε′, M, Z and σac were measured as functions of Au2O3 content.•ε′ was decreased with ...Au2O3 upto 0.04 mol% due to growing presence of PbO4 units.•Observed dipolar relaxation effects were evaluated using Cole-Cole diagrams.•σac exhibited a decreasing trend with Au2O3 content up to 0.04 mol%.•Overall, the presence of red lead was found to reduce the conductivity in these glasses.
Studies on dielectric properties viz., ε′ (dielectric permittivity), M, Z and σac as functions of frequency and temperature (over wide ranges), of glasses/glass-ceramics give quantitative information on their insulating character. Such studies are also useful for understanding structural aspects of these glasses to a great extent. In this work Pb3O4 mixed Li2O-SiO2:Au2O3 glasses were synthesized and heat-treated. Analysis of the results of various characterization techniques indicated increased degree of internal augmentation between various structural groups of the glass network. Observed decrease of ε′ with Au2O3 content up to 0.04 mol% was attributed to the decreased magnitude of space charge polarization due to growing presence of PbO4 units in the glass network. Dipolar relaxation effects of these samples were evaluated using Cole-Cole plots. Variation of conductivity with Au2O3 concentration was analyzed using polaronic tunneling model. Conclusions of these results were found to be in in concurrence with spectroscopic studies. Overall, the presence of Pb3O4 caused reduction the conductivity of these glasses.
•Dinuclear and mononuclear molybdenum(VI) complexes with aroylhydrazonato ligands were tested as catalysts for cyclooctene and oct-1-ene epoxidation.•TBHP in decane provided outstanding results in ...terms of cyclooctene epoxidation: TOF2.5 min >9000 with 0.25 mol % Mo loading.•DFT calculations confirmed the relationship between the ligand nature and reactivity with TBHP and H2O2 as oxidant agents.
Dinuclear and mononuclear molybdenum(VI) complexes with aroylhydrazonato ligands were studied as catalysts for cyclooctene and oct-1-ene epoxidation. Different isomers of the OH and NH2 functionalised aroylhydrazones led to four specific MoO2L units showing different catalytic activity. Three oxidants have been investigated: tert-butylhydroperoxide (TBHP) in water or in decane, and hydrogen peroxide (H2O2). Catalytic processes with TBHP in decane provided outstanding results in the case of cyclooctene epoxidation: TOF2.5 min > 9000 with 0.25 mol % Mo loading. DFT calculations confirmed the relationship between the ligand nature and reactivity with TBHP and H2O2 as oxidant agents. In the case of TBHP as oxidant, calculations considered the solvent in which the oxidant is delivered to the olefin. A plausible mechanism with H2O2 has been proposed after considering various pathways.
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Clostridium perfringens type B and D strains produce epsilon toxin (ETX), which can lead to enterotoxemia, an extremely lethal disease that has significant consequences for the farming of domestic ...ruminants, specifically sheep and goats. The bacterin-toxoids/toxoids enterotoxemia vaccines need time-consuming detoxification steps. Genetically derived toxoids (GTs) can be the alternative vaccines against ETX-associated enterotoxemia. This study was aimed to design, synthesize, and evaluate of five epsilon toxin mutants of C. perfringens by site-directed mutagenesis (SDM).
In this study, five ETX mutants (H106P, I51C, V56C, A114C, and F118C), as ETX-GTs, were designed and synthesized by SDM, which were then cloned in pET-26b (+) and expressed in Escherichia coli /BL21 (DE3). The expression of recombinant ETX-GTs was evaluated by SDS-PAGE, blotting, and ELISA and their toxicity was evaluated by the residual toxicity test based on BP Pharmacopoeia, 2021.
The findings showed that the ETX-GTs could be considered alternative vaccine candidates against ETX-associated enterotoxemia.
These data suggest that I51C mutant could form the basis of an improved recombinant vaccine against enterotoxemia.
Abstract
This study was planned with the aim of identifying the nature and circumstances of the high-graded central core and increasing trend of copper content through depth of 1000 m in Miduk PCD. ...Mechanisms of high-grading, refer to hypogene enrichment (HE), in PCDs poorly understood. Two main hypotheses for hypogene enrichment formation assumed addition of extra copper to the system, alternatively hypogene leaching and enrichment. In order to obtain alteration-mineralization-geochemical pattern both horizontally and vertically, all macroscopic data extracted from relogging of 6800 m’ drill core along an east–west profile, compiled with microscopic observations from studying of 550 thin-polished sections and copper grades of 3400 samples analyzed by XRF and ICP-OES. Our findings proved hypogene enrichment events at deposit. HE evidences in macroscopic and microscopic scales identified almost as various replacement textures between Fe-Cu sulphides and also vein-reopening by later Cu-mineralization and new generation of disseminated or vein type mineralization. In addition, appearance of dark halo, as consuming intermediate chalcocite phase, around pyrite and chalcopyrite which gradually evolves as bornite, also extruding extra iron as fibrous hematite at the outer edge of bornite product replaced chalcopyrite, partially replacement of bornite and chalcopyrite to hypogene chalcocite and covellite-digenite in deep potassic are other HE evidences in the case study. Here, we draw on microscopic observations and SEM-BSE-EDS results, secondary hypogene genesis for some of bornite and chalcopyrite as a hypogene enrichment evidence. Observations from relogging show that potassic alteration has a relatively good preservation in the center of the deposit from depth to surface, but affected by intense overprinting of subsequent alterations towards margins. Evident function of ore-leaching at margins, also elevated copper grades in central parts of the deposit strongly suggest leaching-fixation mechanism. Where buffer potential of the rock is preserved copper fixation and where it totally eliminated almost complete leaching of copper happened. Consequently, we introduce leaching-fixation as index processes in hypogene enrichment at the case study. We suggest that identifying the nature of hypogene enrichment processes and its characterizations not only improve understanding about PCD’s hydrothermal evolution, but also achieve exploration indicators, furthermore, industrial benefits in the production line.
Effects of cell shape and size, and relative density of aluminum foam on its compressive behavior have been investigated. Aluminum foams were produced via aluminum powder-Carbamide spacer route. The ...results show that angular cells significantly reduce mechanical properties of the foam. They also indicate that compressive properties of the foams, including plateau stress ( sigma pl), densification strain ( epsilon D), and energy absorption, increase by cell size and relative density of the foams. Experimental results were compared with theoretical predictions; they were fairly corresponded to theoretical conceptions; this arises from near-ideal architecture of the foams with almost spherical cells, in this study. Constant values of C, n and alpha in theoretical modulus and densification strain equations wear calculated as 1.22, 2.09 and 0.95, respectively. The values indicate compressive behavior approaches to ideal morphology foam via employing spherical space holder.
Actual evapotranspiration (ETa) plays a crucial role in the water and energy cycles of the earth. An accurate estimate of the ETa is essential for management of the water resources, agriculture, and ...irrigation, as well as research on atmospheric variations. Despite the importance of accurate ETa values, estimating and mapping them remains challenging due to the physical and biological complexity of the ET process. As a novel approach for rapid and reliable estimation of ETa, the present study develops automated deep learning (AutoDL) models that incorporate a metaheuristic optimization algorithm for image processing, architectural design, and hyperparameter tuning. The proposed AutoDL models integrate three different spatial and channel attention mechanisms, including a novel activated spatial attention mechanism (ASPAM), with the U-Net architecture. Bypassing the need for meteorological inputs, the proposed framework uses Moderate Resolution Imaging Spectrometer (MODIS) products and Digital Elevation Model (DEM) data as inputs. To evaluate the performance of the models, they are applied to three study areas in the United States with various climatic characteristics. According to the results, during the spring and summer, when the target values have higher certainty, the estimations are highly promising, with R2 as high as 0.91 and MAPE as low as 6.40%. Furthermore, the proposed ASPAM module improves the accuracy of ETa estimations compared to attention gate (AG) and squeeze and excitation (SE) attention modules. The results also indicate that the MODIS raw products and derived vegetation and water indices can predict ETa within a reliable range of accuracy, with the addition of DEM data marginally enhancing the models' performance. The automatic workflow of this model makes it significantly easy to use, contributing to its applicability and generalizability for enhancing atmospheric research.
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