Constituting plasmonic-metal nanostructures is an efficient way in the design and development of active photocatalytic systems. Here we demonstrate a simple one-step reduction process that can in ...situ grow plasmonic silver nanoparticles on the surface of AgTaO3. The exsolution of silver out of AgTaO3 does not seem to have a significant impact on the crystal integrity, whilst its visible light sensitivity is greatly enhanced. Such Ag nanoparticles decorated AgTaO3 system showed improved photocatalytic hydrogen evolution both under visible and full range irradiation.
•We have performed in-situ growth of uniform silver nano-particles on AgTaO3.•The Ag@AgTaO3 shows Enhanced photocatalytic performance under UV and visible light.•The Ag@AgTaO3 microstructure is important for the improved activity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We present a novel approach of antireflection coating using metamaterials. It dramatically reduces the reflection and greatly enhances the transmission near a specifically designed frequency over a ...wide range of incidence angles for both transverse magnetic and transverse electric polarizations. A classical interference mechanism is identified through analytical derivations and numerical simulations. It elucidates that the tailored magnitude and phase of waves reflected and transmitted at boundaries of metamaterial coating are responsible for the antireflection.
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In the last few decades, photocatalysis has been found to be a practical, environmentally friendly approach for degrading various pollutants into non-toxic products (e.g., H2O and CO2) and generating ...fuels from water using solar light. Mainly, traditional photocatalysts (such as metal oxides, sulfides, and nitrides) have shown a promising role in various photocatalysis reactions. However, it faces many bottlenecks, such as a wider band gap, low light absorption nature, photo-corrosion issues, and quick recombination rates. Due to these, a big question arises of whether these traditional photocatalysts can meet increasing energy demand and degrade emerging pollutants in the future. Currently, researchers view heteroanionic materials as a feasible alternative to conventional photocatalysts for future energy generation and water purification techniques due to their superior light absorption capacity, narrower band gap, and improved photo-corrosion resistance. Therefore, this article summarizes the recent developments in heteroanionic materials, their classifications based on anionic presence, their synthesis techniques, and their role in photocatalysis. In the end, we present a few recommendations for improving the photocatalytic performance of future heteroanionic materials.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, Stigonematales sp. microalgae were collected from drain water and characterized for its' morphological edifice, elemental composition, thermal condition and energy generation capacity ...by using scanning electron microscopy, energy dispersive X-ray, thermogravimetric analyzer and bomb calorimeter, respectively. Scanning electron micrographs revealed the top view of microalgae and ash pellet with carbon coated specimens at low voltage (5.0 kV) through the secondary electron image detector. Elemental analysis revealed all the major and minor constituents of this microalgae species and its' ash in terms of dry weight (%) and atomic weight (%). Thermogravimetric analysis was conducted at heating rate, 10 °C/min and this experimental results determined moisture content, volatile matter, ash content and fixed carbon of the sample with 4.5%, 35%, 39.5% and 21%, respectively. Microalgae powder blended with bituminous coal by 75%, 50% and 25% measured calorific value 14.07 MJ/kg, 19.88 MJ/kg and 26.42 MJ/kg, respectively. Microalgae (75%) -coal (25%) blend showed excellent amount of energy content, 24.59 MJ/kg. Microalgae blended with coal unveiled an outstanding outcome with elevation of the volatile matter and drop of the ash content. Optimization of microalgae-coal blend in large-scale application can initiate bright future in renewable energy exploration.
•Stigonematales sp. microalgae collected from drain water as feedstock for bioenergy generation.•30.30%C, 40.87%O and O/C ratio 1.34 as elemental composition.•Improved energy value of microalgae with different ratios of bituminous coal blend.•Thermal profile analysis at heating rate, 10 °C/min.•Increased value of microalgae-coal combustion for optimization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this Letter, we present resonance properties in terahertz metamaterials consisting of a split-ring resonator array made from high-temperature superconducting films. By varying the temperature, we ...observe efficient metamaterial resonance switching and frequency tuning. The results are well reproduced by numerical simulations of metamaterial resonance using the experimentally measured complex conductivity of the superconducting film. We develop a theoretical model that explains the tuning features, which takes into account the resistive resonance damping and additional split-ring inductance contributed from both the real and imaginary parts of the temperature-dependent complex conductivity. The theoretical model further predicts more efficient resonance tuning in metamaterials consisting of a thinner superconducting split-ring resonator array, which are also verified in subsequent experiments.
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Switching the handedness, or the chirality, of a molecule is of great importance in chemistry and biology, as molecules of different handedness exhibit dramatically different physiological properties ...and pharmacological effects. Here we experimentally demonstrate handedness switching in metamaterials, a new class of custom-designed composites with deep subwavelength building blocks, in response to external optical stimuli. The metamolecule monolayer flips the ellipticity and rotates the polarization angle of light in excess of 10° under optical excitation, a much stronger electromagnetic effect than that of naturally available molecules. Furthermore, the experimentally demonstrated optical switching effect does not require a structural reconfiguration, which is typically involved in molecular chirality switching and is inherently slow. The handedness switching in chiral metamolecules allows electromagnetic control of the polarization of light and will find important applications in manipulation of terahertz waves, such as dynamically tunable terahertz circular polarizers and polarization modulators for terahertz radiations.
•Intermediate pyrolysis A. cincinnata &A. holosericea species was studied at 500 °C.•Bio-oils and biochars produced were characterised using standard analysis methods.•Highest yield of bio-oil was ...52.95% from the trunk of A. cincinnata species.•Highest biochar yield was 38.78% from the phyllodes of A. holosericea species.•CVs of bio-oils and biochars were in the range of 23.46–30.65 and 25.57–27.53 MJ/kg.
Ever-increasing energy requirements coupled with the desire to cope with global warming have motivated researchers to look for alternative energy resources. Lignocellulosic biomass is an abundant renewable energy resource which can be exploited to reduce the dependency on fossil fuel resources. Acacia cincinnata and Acacia holosericea are fast-growing tree species which produce large quantities of biomass within short span of time and does not require major agricultural inputs to grow. This study is aimed at the intermediate pyrolysis process of Acacia cincinnata and Acacia holosericea species to produce biofuels such as bio-oil, biochar and gaseous product. Mass balance was done to calculate the yields of different products along with the characterisation of bio-oil and biochar produced. Experiments were carried out in a fixed-bed reactor at the pyrolysis temperature of 500 °C, heating rate of 25 °C/min and nitrogen gas flowrate of 100 cm3/min for the biomass feedstock having particle size between 0.5 and 1 mm. Comprehensive thermochemical characterisation of biomass samples was carried out prior to pyrolysis experiments. The chemical composition of bio-oil samples produced was determined using Gas Chromatography-Mass Spectroscopy (GC–MS) technique. Ultimate analysis, calorific values, pH values and the ash contents in the bio-oil samples were also determined. Bio-oil produced were reported to be complex mixtures of heterocyclic and phenolic compounds resulting from the thermal degradation of basic components of biomass with the calorific values obtained in the range of 23.46–30.65 MJ/kg. Biochar samples produced in the study were characterised with the help of ultimate analysis, FTIR analysis, calorific values, pH values and SEM and EDX analysis. Properties of biochars indicated suitability for energy as well as other applications such as soil remediation and adsorption purposes. Study revealed a decent potential of Acacia cincinnata and Acacia holosericea species as biofuels resources.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Protonic ceramic fuel cells (PCFCs) are one of the promising and emerging technologies for future energy generation. PCFCs are operated at intermediate temperatures (450–750 °C) and exhibit many ...advantages over traditional high-temperature oxygen-ion conducting solid oxide fuel cells (O-SOFCs) because they are simplified, have a longer life, and have faster startup times. A clear understanding/analysis of their specific working parameters/processes is required to enhance the performance of PCFCs further. Many physical processes, such as heat transfer, species transport, fluid flow, and electrochemical reactions, are involved in the operation of the PCFCs. These parameters are linked with each other along with internal velocity, temperature, and electric field. In real life, a complex non-linear relationship between these process parameters and their respective output cannot be validated only using an experimental setup. Hence, the computational fluid dynamics (CFD) method is an easier and more effective mathematical-based approach, which can easily change various geometric/process parameters of PCFCs and analyze their influence on its efficiency. This short review details the recent studies related to the application of CFD modeling in the PCFC system done by researchers to improve the electrochemical characteristics of the PCFC system. One of the crucial observations from this review is that the application of CFD modeling in PCFC design optimization is still much less than the traditional O-SOFC.
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Recently reported metamaterial analogues of electromagnetically induced transparency enable a unique route to endow classical optical structures with aspects of quantum optical systems. This method ...opens up many fascinating prospects on novel optical components, such as slow light units, highly sensitive sensors and nonlinear devices. In particular, optical control of electromagnetically induced transparency in metamaterials promises essential application opportunities in optical networks and terahertz communications. Here we present active optical control of metamaterial-induced transparency through active tuning of the dark mode. By integrating photoconductive silicon into the metamaterial unit cell, a giant switching of the transparency window occurs under excitation of ultrafast optical pulses, allowing for an optically tunable group delay of the terahertz light. This work opens up the possibility for designing novel chip-scale ultrafast devices that would find utility in optical buffering and terahertz active filtering.
Deploying a multi-hop underwater acoustic sensor network (UASN) in a large area brings about new challenges in reliable data transmissions and survivability of network due to the limited underwater ...communication range/bandwidth and the limited energy of underwater sensor nodes. In order to address those challenges and achieve the objectives of maximization of data delivery ratio and minimization of energy consumption of underwater sensor nodes, this paper proposes a new underwater routing scheme, namely AURP (AUV-aided underwater routing protocol), which uses not only heterogeneous acoustic communication channels but also controlled mobility of multiple autonomous underwater vehicles (AUVs). In AURP, the total data transmissions are minimized by using AUVs as relay nodes, which collect sensed data from gateway nodes and then forward to the sink. Moreover, controlled mobility of AUVs makes it possible to apply a short-range high data rate underwater channel for transmissions of a large amount of data. To the best to our knowledge, this work is the first attempt to employ multiple AUVs as relay nodes in a multi-hop UASN to improve the network performance in terms of data delivery ratio and energy consumption. Simulations, which are incorporated with a realistic underwater acoustic communication channel model, are carried out to evaluate the performance of the proposed scheme, and the results indicate that a high delivery ratio and low energy consumption can be achieved.
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