Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can be manipulated. Photonic crystals provide such an environment: they strongly modify the vacuum fluctuations, causing the decay of emitted light to be accelerated or slowed down, to reveal unusual statistics, or to be completely inhibited in the ideal case of a photonic bandgap. Here we study spontaneous emission from semiconductor quantum dots embedded in inverse opal photonic crystals. We show that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal. Modified emission is observed over large frequency bandwidths of 10%, orders of magnitude larger than reported for resonant optical microcavities. Both inhibited and enhanced decay rates are observed depending on the optical emission frequency, and they are controlled by the crystals’ lattice parameter. Our experimental results provide a basis for all-solid-state dynamic control
of optical quantum systems.

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals

A review of the multi-component utilisation of coal fly ash

Utilization of rice husk ash as silica source for the synthesis of mesoporous silicas and their application to CO2 adsorption through TREN/TEPA grafting

. Silica, SiO2, in dissolved (DSi) and particulate (PSi) form, is both a major product of continental weathering as well as an essential nutrient in terrestrial and aquatic systems. Here we present estimates of the spatial distribution of riverine silica fluxes under natural conditions, i.e. without human influence, to ~140 segments of the global coastal zone. Focussing on the construction of the DSi budget, natural DSi concentration is multiplied with discharge of rivers for each segment for documented basins and segments. Segments with no documentation available are estimated using clustered information based mainly on considerations of local lithology, climate, and lake retention. We approximate fluxes of particulate silica in various forms (PSi) from fluxes of suspended matter, calculated from existing models. Results have been established for silica fluxes, concentrations and yields for drainage basins of the different continents, oceans basins as well as coastal segment basins. For the continental surfaces actually draining into the oceans (exorheic regions, representing 114.7 million (M) km2), 371 M t y−1 of DSi and 8835 M t y−1 of PSi are transported, corresponding to a mean concentration of 9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1 and 77 t km−2 y−1, respectively. DSi yields exceeding 6.6 t km−2 y−1, i.e. >2× the global average, represent 17.4% of the global continental ice-free exorheic area but correspond to 56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active areas (>5× global average), suggesting a close connection between tectonic activity and DSi fluxes resulting from silicate weathering. The macro-filters of regional and marginal seas intercept 33% and 46% of the total dissolved and particulate silica fluxes. The mass of DSi received from rivers per unit square area of various oceans ranges over more than one order of magnitude. When expressed per unit volume and when individual regional seas are considered this figure ranges over two to three orders of magnitude, an illustration of the heterogeneity of the land to sea connection.

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Global spatial distribution of natural riverine silica inputs to the coastal zone

Utilization is one of the prominent strategies for the management of hazardous industrial wastes like fly ash. As fossil-based power is expected to remain a major source of global electricity supply in the coming years, the absence of effective management strategies will exacerbate the problem of fly ash waste in the environment. Global fly ash utilization rates remain low due to limited utilization opportunities outside the construction industry. This necessitates the development of new pathways for its utilization as a means of diverting it from landfills where it poses a significant threat to the environment. Carbon capture, utilization, and storage presents opportunities to utilize fly ash in various ways; as a capture material, as a medium for permanent CO2 storage via mineralization, and as a catalyst or catalyst support for CO2 utilization processes. This study reviews the different technologies through which fly ash and materials derived from fly ash are applied in the CO2 capture, utilization, and storage technology while highlighting some challenges and opportunities for further research and development.

Applications of fly ash for CO2 capture, utilization, and storage

Processing of mesoporous silica materials (MCM-41) from coal fly ash

Techno-economic analysis of electricity generation from biogas using palm oil waste

Corrosion is the deterioration of materials due to chemical reaction with the environment. It is reverse extractive metallurgy, which is dependent on temperature and concentration of environment. Other factors such as stress and erosion also affect the corrosion rate. This article is limited on reviewing different types of corrosion for metals and its alloys. The annual corrosion costs range from 1 to 5% of GNP for any nations. The impact of corrosion is not only related with cost but also with safety hazards and life losses. Hence, proper action must be taken to control and prevent corrosion.

Corrosion of Metals: Overview

One of the most efficient and effective solutions for sustainable energy supply to supplement the increasing energy demand and reducing environment pollution is renewable energy resources. Malaysia is currently the world's second largest producer and exporter of palm oil and 47% of the world's supply of palm oil is produced by this country. Nearly 80 million tonnes of Fresh Fruit Bunches (FFB) are processed annually in 406 palm oil mills and are generating approximately 54 million tonnes of palm oil mill effluent (POME), known to generate biogas consisting of methane – a Green House Gas (GHG) identifiable to cause global warming. This is 21 times more potent GHG than CO2. These two major oil palm wastes are a viable renewable energy (RE) source for production of electricity. If the two sources are used in harnessing the renewable energy potential the pollution intensity from usage of non-renewable sources can also be reduced significantly. This study focused on the pollution mitigation potential of biogas as biogas is a renewable energy. Utilization of this renewable source for the production of electricity is believed to reduce GHG emissions to the atmosphere.

https://iopscience.iop.org/article/10.1088/1755-1315/16/1/012026/pdf

Use of Oil Palm Waste as a Renewable Energy Source and Its Impact on Reduction of Air Pollution in Context of Malaysia

This paper exclusively describes the biocompatibility evaluation of biodegradable PLA–HA-based composites as temporary bone scaffolds for bone tissue engineering in orthopaedic applications. For th...

Shahida Begum

Papers

Processing of mesoporous silica materials (MCM-41) from coal fly ash

Techno-economic analysis of electricity generation from biogas using palm oil waste

Corrosion of Metals: Overview

Use of Oil Palm Waste as a Renewable Energy Source and Its Impact on Reduction of Air Pollution in Context of Malaysia

Effect of compatibilizers on in vitro biocompatibility of PLA–HA bioscaffold