In this work, the exceptionally improved sensing capability of highly porous three-dimensional (3-D) hybrid ceramic networks toward reducing gases is demonstrated for the first time. The 3-D hybrid ...ceramic networks are based on doped metal oxides (Me x O y and Zn x Me1–x O y , Me = Fe, Cu, Al) and alloyed zinc oxide tetrapods (ZnO-T) forming numerous junctions and heterojunctions. A change in morphology of the samples and formation of different complex microstructures is achieved by mixing the metallic (Fe, Cu, Al) microparticles with ZnO-T grown by the flame transport synthesis (FTS) in different weight ratios (ZnO-T:Me, e.g., 20:1) followed by subsequent thermal annealing in air. The gas sensing studies reveal the possibility to control and change/tune the selectivity of the materials, depending on the elemental content ratio and the type of added metal oxide in the 3-D ZnO-T hybrid networks. While pristine ZnO-T networks showed a good response to H2 gas, a change/tune in selectivity to ethanol vapor with a decrease in optimal operating temperature was observed in the networks hybridized with Fe-oxide and Cu-oxide. In the case of hybridization with ZnAl2O4, an improvement of H2 gas response (to ∼7.5) was reached at lower doping concentrations (20:1), whereas the increase in concentration of ZnAl2O4 (ZnO-T:Al, 10:1), the selectivity changes to methane CH4 gas (response is about 28). Selectivity tuning to different gases is attributed to the catalytic properties of the metal oxides after hybridization, while the gas sensitivity improvement is mainly associated with additional modulation of the electrical resistance by the built-in potential barriers between n-n and n-p heterojunctions, during adsorption and desorption of gaseous species. Density functional theory based calculations provided the mechanistic insights into the interactions between different hybrid networks and gas molecules to support the experimentally observed results. The studied networked materials and sensor structures performances would provide particular advantages in the field of fundamental research, applied physics studies, and industrial and ecological applications.
The deterioration of water quality by pollutants is a major health issue. Actual remediation methods are limited, and, as a consequence, there is a need for new remediation technologies. In ...particular, nanomaterials of unique properties have been recently developed for remediation. Here, we review mechanisms and applications of carbon-based nanomaterials for the adsorption and photocatalytic removal of organic and inorganic pollutants in wastewaters. Nanomaterials allow enhanced adsorption due to strong interactions between pollutants and adsorption sites. In photocatalysis, enhanced efficiency is attributed to the improved light harvesting and reduced recombination of photo-induced electrons and holes.
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•Designing of novel thiazole Schiff base ligands (EVTA(HL)).•Condensation of metal (Co+2/Ni+2/Cu+2/Zn+2) salts with EVTA to synthesize metal complexes (EVTA (A-D)).•Characterization ...of synthesized compounds by FT-IR, UV–Visible, Mass spectral, P-XRD, Cyclic voltammetry and TGA for thermal stability.•Theoretical computational studies utilizing the DFT/B3LYP at the 6-31G basic set for novel Schiff base ligand and LANL2DZ basis set for metal complexes.•Significant antifungal, DNA cleaving,DNA binding and antioxidant activities and fluorescence property by all metal complexes and ligand.
Cobalt, Copper, Nickel and Zinc coordinated metal complexes were synthesized by novel thiazole Schiff base ligand 2-ethoxy-4-((5-methylthiazol-2-ylimino)methyl) phenol derived from 3-ethoxy-4-hydroxybenzaldehyde and 2-amino- 5-methylthiazol. The synthesized compounds were spectrochemically characterized by elemental analysis, molar conductance, FT-IR, UV–Vis, Mass spectral analysis, Powdered-XRD and cyclic voltammetry. The thermal stability of synthesized complexes were investigated by using thermogravimetric analysis (TGA). Theoretical computational study were performed for all the synthesized compounds utilizing the DFT/B3LYP method at the 6-31G basic set for Schiff base ligand whereas LANL2DZ basis set for metal complexes. Molecular Electrostatic Potential (MEP), HOMO-LUMO, Mulliken charges and global reactivity descriptors, including chemical potential (μ), global softness (S), chemical hardness (η), and electrophilicity index (ω) were measured and correlated with antimicrobial activity. The synthesized thiazole Schiff base ligand and its coordinated metal complexes shows good antifungal agreement against Fusarium Oxysporum and Aspergillus Niger species. These compounds also exhibit DNA binding, DNA cleaving and antioxidant activity. All the synthesized molecules indicate potential fluorescence property.
The application of nanomaterials as nanosorbents in solving environmental problems such as the removal of heavy metals from wastewater has received a lot of attention due to their unique physical and ...chemical properties. These properties make them more superior and useful in various fields than traditional adsorbents. The present mini-review focuses on the use of nanomaterials such as dendrimers, mesoporous silicas and chitosan nanosorbents in the treatment of wastewater contaminated with toxic heavy-metal ions. Recent advances in the fabrication of these nanoscale materials and processes for the removal of heavy-metal ions from drinking water and wastewater are highlighted, and in some cases their advantages and limitations are given. These next-generation adsorbents have been found to perform very well in environmental remediation and control of heavy-metal ions in wastewater. The main objective of this review is to provide up-to-date information on the research and development in this particular field and to give an account of the applications, advantages and limitations of these particular nanosorbents in the treatment of aqueous solutions contaminated with heavy-metal ions.
Plant—based antimicrobials and antioxidants represent a vast untapped source for medicines and food supplements and hence have enormous therapeutic potential. Present work reports the fungicidal ...potential of Cinnamomum tamala Nees & Eberm (Lauraceae) leaf oil against five food spoilage and pathogenic fungi. In addition antioxidant efficacy of seven different solvent extracts derived from leaf was also evaluated using in vitro models. The oil demonstrated potent antifungal activity against Aspergillus niger, A. fumigatus, Candida albicans, Rhizopus stolonifer and Penicillium spp. in agar diffusion assay. Zone of inhibition ranged from 17-25 mm. The MFC values of oil against all the test fungi were found to be 230μg/ml. Phytochemicals present in C. tamala leaf were extracted in several solvents for assessing their effect in oxidative defense. The extracts exhibited appreciable antioxidant activity in β-carotene bleaching assay and reducing power assay. The antioxidative activities of extracts were compared with the activities of standard antioxidant compounds BHA and ascorbic acid. Petroleum ether, ethanol, acetone and chloroform extracts exhibited about 30-67% antioxidant activity in β-carotene bleaching assay. Aqueous and ethanol extracts exhibited better reducing power which increased gradually with increasing amount of the extract concentration showing dose dependent response. Results indicated that natural phytochemicals present in C. tamala leaf extracts have potential to prevent growth of food spoilage/pathogenic fungi. In addition they also have capability to mitigate the oxidative stress by antioxidant response.
This paper reviews dissimilatory nitrate reduction to ammonium (DNRA) in soils - a newly appreciated pathway of nitrogen (N) cycling in the terrestrial ecosystems. The reduction of NO3− occurs in two ...steps; in the first step, NO3− is reduced to NO2−; and in the second, unlike denitrification, NO2− is reduced to NH4+ without intermediates. There are two sets of NO3−/NO2− reductase enzymes, i.e., Nap/Nrf and Nar/Nir; the former occurs on the periplasmic-membrane and energy conservation is respiratory via electron-transport-chain, whereas the latter is cytoplasmic and energy conservation is both respiratory and fermentative (Nir, substrate-phosphorylation). Since, Nir catalyzes both assimilatory- and dissimilatory-nitrate reduction, the nrfA gene, which transcribes the NrfA protein, is treated as a molecular-marker of DNRA; and a high nrfA/nosZ (N2O-reductase) ratio favours DNRA. Recently, several crystal structures of NrfA have been presumed to producee N2O as a byproduct of DNRA via the NO (nitric-oxide) pathway. Meta-analyses of about 200 publications have revealed that DNRA is regulated by oxidation state of soils and sediments, carbon (C)/N and NO2−/NO3− ratio, and concentrations of ferrous iron (Fe2+) and sulfide (S2−). Under low-redox conditions, a high C/NO3− ratio selects for DNRA while a low ratio selects for denitrification. When the proportion of both C and NO3− are equal, the NO2−/NO3− ratio modulates partitioning of NO3−, and a high NO2−/NO3− ratio favours DNRA. A high S2−/NO3− ratio also promotes DNRA in coastal-ecosystems and saline sediments. Soil pH, temperature, and fine soil particles are other factors known to influence DNRA. Since, DNRA reduces NO3− to NH4+, it is essential for protecting NO3− from leaching and gaseous (N2O) losses and enriches soils with readily available NH4+-N to primary producers and heterotrophic microorganisms. Therefore, DNRA may be treated as a tool to reduce ground-water NO3− pollution, enhance soil health and improve environmental quality.
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•DNRA is a novel and shortest biological pathway of N-cycling in terrestrial ecosystems where NO3- is reduced to NH4+ in soils•This pathway has potential to reduce N2O emissions and protect NO3- from leaching losses•It outcompetes the denitrification process under limited NO3- availability in the system•It enriches soil with NH4+-N and make available to primary producers as N-fertilizer•Meta-analyse revealed that DNRA is mainly regulated by C/N ratio, NO2- / NO3- ratio and S2-
The present analysis describes the effect of dissipative heat energy transfer in Ethylene–Glycol (EG) based on conducting nanofluid over a heated semi-infinite vertical plate past through a porous ...medium. Uniform magnetic field, heat source/sink, and the effect of particle concentration also have been discussed by incorporating in the energy and solutal transfer equations, respectively. In addition to that, the thermal properties of the nanofluid are affected by the thermal slip boundary condition since; the temperature slip is favorable for the reduction in the heat transfer. Assuming self-similar transformations, the governing PDEs are transformed into non-linear coupled ODEs. These transformed equations are solved by using semi-analytical techniques such as Adomian Decomposition Method (ADM). The characteristics of different parameters on the flow phenomena are obtained and presented via graphs. The numerical values of the thermophysical properties of both the nanoparticles and the base fluid are shown in the table. Validation of the present work is obtained by comparing our result with the earlier established result and it is found that both the results are coinciding with each other. However, the main quantified results are the following: due to heavy density of the Cu nanoparticles, increasing volume fraction in ethylene–glycol base fluid resists the fluid motion and the inclusion of dissipative heat energy is favorable to enhance the nanofluid temperature.
Isoprene, formaldehyde and acetaldehyde are important reactive organic compounds which strongly impact atmospheric oxidation processes and formation of tropospheric ozone. Monsoon meteorology and the ...topography of Himalayan foothills cause surface emissions to get rapidly transported both horizontally and vertically, thereby influencing atmospheric processes in distant regions. Further in monsoon, Indo-Gangetic Plain is a major rice growing region of the world and daytime hourly ozone can frequently exceed phytotoxic dose of 40 ppb O3. However, the sources and ambient variability of these compounds which are potent ozone precursors are unknown. Here, we investigate the sources and photochemical processes driving their emission/formation during monsoon season from a sub-urban site at the foothills of the Himalayas. The measurements were performed in July, August and September using a high sensitivity mass spectrometer. Average ambient mixing ratios (±1σ variability) of isoprene, formaldehyde, acetaldehyde, and the sum of methyl vinyl ketone and methacrolein (MVK+MACR), were 1.4 ± 0.3 ppb, 5.7 ± 0.9 ppb, 4.5 ± 2.0 ppb, 0.75 ± 0.3 ppb, respectively, and much higher than summertime values in May. For isoprene these values were comparable to mixing ratios observed over tropical forests. Surprisingly, despite occurrence of anthropogenic emissions, biogenic emissions were found to be the major source of isoprene with peak daytime isoprene driven by temperature (r ≥ 0.8) and solar radiation. Photo-oxidation of precursor hydrocarbons were the main sources of acetaldehyde, formaldehyde and MVK+MACR. Ambient mixing ratios of all the compounds correlated poorly with acetonitrile (r ≤ 0.2), a chemical tracer for biomass burning suggesting negligible influence of biomass burning during monsoon season. Our results suggest that during monsoon season when radiation and rain are no longer limiting factors and convective activity causes surface emissions to be transported to upper atmosphere, biogenic emissions can significantly impact the remote upper atmosphere, climate and ozone affecting rice yields.
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•First monsoon time in-situ measured dataset of isoprene, formaldehyde and acetaldehyde from India.•Evidence of strong biogenic isoprene emission during monsoon season.•Temperature was the main driving factor for biogenic isoprene.•Photo-oxidation of hydrocarbons were the main source of formaldehyde and acetaldehyde.
The objective of investigation was to prepare nanoemulsion containing risperidone (RSP) to accomplish the delivery of drug to the brain via nose. Risperidone nanoemulsion (RNE) and mucoadhesive ...nanoemulsion (RMNE) were characterized for drug content, pH, percentage transmittance, globule size and zeta potential. Biodistribution of RNE, RMNE, and risperidone solution (RS) in the brain and blood of Swiss albino rats following intranasal (i.n.) and intravenous (i.v.) administration was examined using optimized technetium labeled (
99mTc-labeled) RSP formulations. Gamma scintigraphy imaging of rat brain following i.v. and i.n. administrations were performed to ascertain the localization of drug in brain. The brain/blood uptake ratio of 0.617, 0.754, 0.948, and 0.054 for RS (i.n.), RNE (i.n.), RMNE (i.n.), and RNE (i.v.), respectively, at 0.5
h are indicative of direct nose to brain transport bypassing the blood–brain barrier. Higher drug transport efficiency (DTE%) and direct nose to brain drug transport (direct transport percentage, DTP%) for mucoadhesive nanoemulsions indicated more effective and best brain targeting of RSP amongst the prepared nanoemulsions. Studies conclusively demonstrated rapid and larger extent of transport of RSP by RMNE (i.n.) when compared to RS (i.n.), RNE (i.n.) and RNE (i.v.) into the rat brain.
Juvenile nasopharyngeal angiofibroma often attaches firmly to the adjoining bony region around the sphenopalatine foramina-sphenopalatine fossa-pterygomaxillary fissure. This can result in ...hourglass-shaped constriction and predispose to incomplete resection (residual disease) with a transpalatal approach. This paper describes attempts to address this 'inaccessible' area with a novel instrument, used since 2012.
Measurements of the sphenopalatine foramen, nasal septum, posterior nasopharyngeal wall and hard palate were undertaken in 20 skulls and 10 computed tomography scans (lateral extension). A device was designed (in terms of angulation and length) following several trials with malleable wire. A search of patents was also undertaken. Recurrence rates were compared in cases of device use and non-use.
The novelty of the sphenopalatine fossa dissector was established and the device was patented. This device has significantly improved our 17.59 per cent recurrence rate of the past 4 decades; of 63 cases over 3 years, there were only 3 recurrences and 2 residual disease cases. Findings of our previous studies with or without the device are compared.
Existing evidence supports the incorporation of this inexpensive instrument in the armamentarium for resecting lateral extension of juvenile nasopharyngeal angiofibroma during a transpalatal approach.
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