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Dams have been built in many parts of the world since the earliest human civilizations, but currently there is a significant program of dam building underway in the tropics. Despite general awareness of the likely detrimental impacts of dams, the limited number of empirical tropical studies means that specific effects of dams on these important but imperilled ecosystems are hard to predict. Although the Functional Flows (FFs) concept is now prominent in the scientific and river management literature, it has been applied only to some very specific cases in tropical areas to guide dam operation (e.g. to support periodic flooding of floodplain areas). In these and many other cases, FFs have been applied retrospectively, to design operational flows for existing dams. The work presented in this thesis concerns development of flow recommendations prior to the construction of a large tropical hydropower dam on Baleh River, Sarawak. Specific objectives of the thesis are to: (i) develop a full statistical understanding of the natural hydrological regime of Baleh River, (ii) identify critical habitat forming discharges (those responsible for coarse sediment entrainment and transport) and relations between discharge magnitude and hydraulic habitat heterogeneity, (iii) to assess the impact of the dam and other land use changes on sediment connectivity, and (iv) provide specific recommendations for dam operation to support sediment entrainment and maintenance of habitat heterogeneity, and for management of lake levels to limit changes in connectivity. The work involved analyses of historical data along with a number of empirical field data collection, modelling and remote sensing approaches. For Objective (i), a 51-year hydrological and hydro-climatological dataset was analysed in order to characterise the natural hydrological regime of the Baleh River. The analyses focussed on understanding the frequency, magnitude, duration, and timing of natural high and low flow events. For Objective (ii), HEC-RAS® models were built for 3 study reaches. These models were used to simulate hydraulic conditions across the range of discharges extending from high to low flows. The output from the hydraulic models was combined with information on critical entrainment thresholds of sediment at the 3 reaches in order to understand which flows are capable of entraining sediment. The focus of these analyses was to understand whether the expected hydropower regime is likely to cause sediment entrainment in the way that occurs currently under the natural regime. The analyses also used HEC-RAS® to evaluate hydraulic habitat heterogeneity at low flow conditions. The HEC-RAS® modelling was integrated with Soil and Water Assessment Tool (SWAT® or ArcSWAT®) to understand flow magnitude in the river under different conditions of hydropower operation and rainfall (which would lead to tributaries downstream from the dam discharging high flows to the mainstem Baleh). In addition, the model coupled with the DEMs was used to look at the extent of exposure of gravel bars during low flow conditions. The SedInConnect model was used to understand patterns of sediment connectivity across the Baleh catchment. This model computes the sediment connectivity index (IC). For the modelling, it was necessary to develop DEMs and collate information on landcover in order to calculate topographic roughness and IC. Information on sediment entrainment was used to make recommendations about flows needed to maintain the geomorphic processes (i.e. bedload transport) post-impoundment that occur currently in the natural river. The low flow analyses were used to understand whether hydraulic conditions became more or less heterogeneous at low flows. The hydrological analyses identified 5 distinct classes of high flow event in the Baleh (defined as 'Event Types'). These types have distinct magnitudes and durations. HEC-RAS® modelling indicated that the smallest of these events led to sediment entrainment of D16 and greater at the study sites, and that larger events resulted in increasing areas of the bed across the study reaches experiencing entrainment. The maximum likely hydropower releases are smaller in discharge magnitude than the smallest of these natural events. The modelling indicated that more or less no sediment entrainment would occur during normal hydropower operations. However, integration of the HEC-RAS® and ArcSWAT® models indicated that when the catchment is wet, tributaries are contributing enough flow to result in sediment entrainment at the study sites that equates to that under some of the higher natural event types. Hydraulic habitat heterogeneity was relatively high during low flows and dropped at moderate and high flows. Moreover, at low flows, gravel bars became exposed at some of the study sites adding to overall habitat heterogeneity. According to the IC models, the impact of historical landcover changes on connectivity between the Baleh and the Rajang has not been pronounced. However, the models predicted that future forest clearance and roads will have observable impacts on the connectivity between the Baleh and Rajang. The models indicated that the construction of the dam would result in a significant impact on connectivity, with the effects of impoundment being greater than those of road and landcover changes, leading to a large portion of the Baleh catchment being almost completely disconnected from the Rajang. The operation of the dam will affect IC upstream of the dam due to the changes in connectivity caused by different lake levels. The HEC-RAS® modelling suggested that over time, in the absence of significant bed entrainment and transport of material, the bed could be expected to become progressively armoured and coarser, as seen in dammed rivers worldwide. However, the modelling also indicated that when the catchment is wet and downstream tributaries are contributing much additional water, flows in the Baleh will greatly exceed turbine releases and appreciable entrainment of bed material can be expected. Recommendations for geomorphic functional flows are made on the basis of these findings. Recommendations are to ensure that hydropower releases using the maximum number of turbines are made during times when the catchment is already wet, to ensure entrainment of bed sediment. Based on analyses of the natural regime, the recommendations include suggestions for timing and duration of such releases. They should last around 20 days, occurring 8 to 15 times per year, predominantly during the wet season. Low flow recommendations were made to occasionally allow dam releases to drop to 1 to 3 turbines to mimic natural low flow events. The recommendation for these events was to allow flow to drop to the natural respective monthly baseflows; these flows should last around 3 days with a frequency of at least 3 times per month during the wet season, and 2 times per month during the dry season. The dam will disconnect a major part of the Baleh catchment from the Rajang. The modelling suggested that the effects of the dam on connectivity will swamp the effects of landcover change and road construction on connectivity. Nevertheless, localised impacts of the road were predicted by the model, with an increase in connectivity on the upslope areas. It is recommended that measures to mitigate this are implemented as part of road construction and management. The model suggested that careful management of lake levels could be used to reduce the impact of the dam on connectivity in the upper part of the basin. The study of functional flows presented in this thesis is of growing importance for sustainable catchment management, particularly in Southeast Asia, where rapid dam construction and vulnerability to the impacts of climate change are prevalent. It is one of few studies globally that has explicitly considered fluvial processes when developing functional flow recommendations. It is also novel in integrating reach scale HEC-RAS® models with catchment scale SWAT® models to help in the design of functional flow recommendations. As far as the author is aware, it is the only study globally to have used the SedInConnect model to understand the combined and interactive effects of damming, landcover change and road construction on structural connectivity at a catchment scale. These approaches can be applied to large rivers in Southeast Asia and other Global South regions, aiding sustainable catchment and water management. It is one of few functional flow studies to have been undertaken before dam closure, allowing us to implement functional recommendations in advance of construction, rather than retrofitting them to a river that has been regulated for some time. It is recommended that a program of monitoring is implemented in the Baleh in order to understand how the river changes in response to impoundment and the success of flow recommendations for maintaining sediment dynamics and habitat heterogeneity. This monitoring will provide the basis for adaptive management.

Protein-templated gold nanoclusters (AuNCs) are emerging nanomaterials with diverse applications in biomedical fields. AuNCs display discrete energy levels, large Stokes shift, good water solubility, distinctive fluorescence properties, high photostability and biocompatibility. These features make AuNCs a perfect candidate for imaging, biosensing and theranostics in the cellular and molecular level. This project aims to develop AuNCs-based platform tools for biosensing applications. First, a facile and optimised protocol for the fabrication of BSA/AuNCs is developed. The protocol requires shorter synthesis time (only 6 h) and lower protein amount (only 20 mg mL-1 ), while giving higher QY (10.62 %). Functionalisation of reduced graphene oxide (rGO) with folic acid (FA) is performed using EDC/NHS cross-linking agents and their interaction after loading with BSA/AuNCs is demonstrated. Finally, a fluorescence "turnoff" sensing strategy is developed using the as-synthesised FA-rGO-BSA/AuNCs for sensitive and selective detection of glutathione. The strategy requires incubation time as short as 2 min only to observe a linear range from 0 to 1.75 µM and LOD of 0.1 µM towards GSH under pH 7.4. Following this, RNase A/AuNCs is synthesised using the optimised protocol. An RNase A/AuNCs-based platform is used to detect the presence of metal ions in aqueous solution. Besides, the activity of RNase A protein after the formation of RNase A/AuNCs is studied. It is found that 50.8 % of RNase A remain active in RNase A/AuNCs. The addition of FArGO onto RNase A/AuNCs serve as a "turn-on" and "turn-off" fluorescence sensor for biosensing of sodium and potassium ions. Lastly, since electroanalytical methods are fast, simple, sensitive and cost-effective, electrochemical approaches have been used, as a proof-of-concept, to investigate the interaction between FA and folate receptor, on a graphene platform. With this, laser scribed graphene oxide (GO) and GO-FA electrodes have been prepared using different approaches for the studies. Ru(NH3)6Cl3 is found to be more suitable to be used as the redox probe in the present electrochemical measurements than Fe2+/Fe3+. Meanwhile, different GO platforms have been studied using various substrates. Overall, these facile fabricated AuNCs-based biosensors pave the way and highlight the possibilities to detect important biomarkers in cancer cells, presenting potential nanotheranostic applications in biological detection and clinical diagnosis.

The dispersion of powders in water is a key step in many process industries. During dispersion, the powder grains often form heterogeneous lumps that are wet outside and dry inside, the presence of which reduces the efficiency of the overall dispersion process. Often, it is difficult to predict and control the conditions under which lump formation occurs. This study considers the consequences of adding insoluble grains to a static air-liquid interface from a funnel. By continuing to add grains, the stacks grow until either the lower grains disperse in the liquid, or the complete stack breaks free from the surface and sinks as a lump. Herein, the effects of grain contact angle, density, size and mass flow rate on these processes are studied experimentally and a theoretical analysis given. The maximum number of grains scales with the Bond Number (Bo) as Bo-1.82 when stack detachment is observed and with an exponent -2.0 when grains disperse into the liquid. As a result of these different scaling exponents, a critical Bond number above which grains wet and disperse can be identified. Moreover, the formation of a jet, entraining air into the liquid occurs when the kinetic energy of the grains are sufficiently high. In the case of a moving liquid, stack formation is also assessed in a purpose-built 2-D flow cell. The understanding gained from the foregoing analysis of dispersion or lump formation of insoluble grains is used to study the rehydration performance of soluble food powders. The subsequent discussion also considered the factors influencing the rehydration process of food powders, focussing on powder properties, including moisture content, molecular weight, grain size and density, as well as the agitation speed, liquid temperature and the mass flow rate of powders added to the liquid. The present findings have identified conditions under which lump formation occurs, and hence how these undesired phenomena can be avoided in applications requiring the efficient dispersion of grains across a liquid interface such as in the reconstitution of dehydrated food powders.