A Novel Method to Monitor Sequential Displacement of Capped Ligands in Gold Nanoparticles [abstract]

Nanoscience Poster SessionNanochemistry of ligand displacement reactions has attracted much attention in recent years for the development of myriad of new gold nanomaterials. Gold nanoparticles have shown applications ranging from tumor imaging agent in nanomedicine to single electron devices in information technology. New gold materials are synthesized by exchange of neutral or anionic ligands with thiolated molecules. Completion of ligand substitution reactions in gold nanoparticles are monitored by using UV-Vis spectrometry. However, there are no methods available to monitor the sequence of the ligand substitution reactions. Monitoring and predicting the sequence of ligand substitutions would provide a convenient handle for the design and development of hybrid nanomaterials containing two or more ligands. In this context, we have developed a novel technique utilizing disc centrifuge systems to monitor the sequential displacement of ligands in various gold nanoconstructs. In our studies, we have used gold nanoparticles stabilized with both anionic and neutral ligands. Gold nanoparticles of various different substitutions have been identified and characterized by disc centrifuge systems. Details of substitution reactions and mechanism on monitoring the sequential displacement using strong ligands will be presented

Impact of land use changes and management practices on groundwater resources in Kolar district, Southern India

Study region: This study analyzes the impact of land use changes on the hydrology of Kolar district in the state of Karnataka, India. Kolar receives on average 565 mm (σ = 130) rainfall during June to October and has a wide gap between its water supply and demand. Study focus: This research identifies the reasons and causes of the gap. A water balance model was successfully calibrated and validated against measurements of groundwater level, recharge and surface runoff. New hydrological insights for the region: The study revealed that between 1972 and 2011, there was a major shift from grass and rainfed crop lands to eucalyptus plantation and irrigated cultivation. About 17.7 % and 18 % of the district area converted into eucalyptus plantation and irrigated lands during this period, respectively. Eucalyptus plantations tended to cause large losses by ET leading to increase in soil moisture deficit and reduction in the recharge to groundwater and in surface runoff (approx. 30 %). The irrigation demand of the district increased from 57 mm (1972) to 140 mm (2011) which resulted in increased groundwater abstraction by 145 %. The expansion of the irrigated area is the major contributing factor for widening the demand-supply gap (62 %) of the freshwater availability. Results could help various stakeholders, including district and national authorities to develop the most suitable water management strategies in order to close the gap between water supply and demand

An assessment of future climatic and anthropogenic impacts on the hydrological system of a semi-arid catchment

Climate and catchment characteristics, particularly land and water use and management, may vary according to the population growth rate, future food habits and water demands. Three climate simulations corresponding to the Intergovernmental Panel on Climate Change, Special Report on Emissions Scenarios (A1B) were downscaled using the ‘Providing Regional Climates for Impact Studies’ (PRECIS) for the period 1961–2098, and bias correction was performed using the quantile mapping (QM) method. A semi-distributed integrated model (Modified Soil and Water Assessment Tool, SWAT) was used to predict the impacts of dynamic changes in catchment characteristics in the Himayat Sagar (HS) catchment and the effects of future climate change on future streamflow and groundwater storage. Simulations predicted that if this trend continues in the future, future climate and anthropogenic changes will lead to a more than 50% reduction in streamflow and a 50% increase in actual evaporation in the HS catchment. This would reduce groundwater storage to a depth of 15 m compared to current conditions, and by the end of the century, there would be no contribution from the base flow to the streamflow. Overall, unless current policies are modified to stabilize land and water management practices, anthropogenic changes will have greater importance than climate change

An assessment of climatic and anthropogenic impacts on the hydrological system of Himayat Sagar Catchment, India

© 2018 Dr. Rajesh NuneMany regions of the world face water shortages that are likely to become more severe in the future. Multiple drivers are responsible for the hydrological change in catchments and these can be exogenous (change in climate variability and mean), endogenous (anthropogenic changes in catchment characteristics) or both. Water shortages, especially streamflow and groundwater storage, lead to impacts on water users within and outside the catchment, which are typically more severe for downstream users. Both exogenous and endogenous changes can have a large impact on catchment hydrology and they need to be considered together. This research aims to understand such changes in the Himayat Sagar (HS) catchment, India, where significant reductions in streamflow and declining groundwater storage have been observed for a couple of decades. This thesis aims first, to examine different changes that have taken place in HS climate and catchment characteristics, apply statistical, conceptual and hydrological modelling approaches to relate and attribute the observed changes to the trends in both the streamflow and groundwater storage and then examine potential future changes through scenario analysis. To support that analysis a field investigation was undertaken to collect information on various catchment characteristics. An analysis of the available data showed that HS streamflow has declined at a rate of 3.6 mm/y without significant changes in rainfall, over the period 1980 to 2007. Analysis indicated that evapotranspiration from the catchment have increased significantly due to landuse change. Different approaches to estimate evaporation based on the different catchment changes were used. Evapotranspiration estimates based on well inventories suggested an increase of 7.2 mm/y, whereas changes in irrigation area combined with typical irrigation practices suggests applied water increased by 9.0 mm/y. Estimates of evapotranspiration using remote sensing data showed an increasing rate of 4.1 mm/y. Changes in surface water storage capacity and interception of various small watershed development structures have also occurred and these increased by 2 mm over 7 years. These changes have likely increased recharge while reducing the streamflow of the catchment. Overall, the expansion of agricultural irrigation area led to an increase in groundwater extractions and decrease in groundwater levels, which effected the contribution of groundwater discharge (baseflow) to streamflow of the HS catchment. The second major analysis step aimed to detangle the individual and combined impacts of HS climate and catchment changes on hydrology in the past through modelling. A coupled semi-distributed surface and groundwater model, the Modified SWAT was used to model the hydrologic impacts of changes in Himayat Sagar catchment characteristics. The model was able to predict the trends in streamflow and groundwater levels well. Simulations including various subsets of catchment changes were used to separate different impacts; notably changes in hydrological structures that aim to intercept runoff and increase recharge, changes in land use, especially irrigation expansion and changes in meteorological forcing. A reduction in average annual simulated streamflow for the validation period of 2 mm or less was found when hydrological structure changes were added into a simulation. Nearly 50% of the total amount of water harvested by the hydrologic structures ultimate contributed to simulated streamflow as baseflow from the groundwater storage. Land use change and associated water extractions led to an increase of 44 mm in simulated catchment average annual irrigation amount. Which led to a net water withdrawal of 25 mm and to a decrease in streamflow of 19 mm, primarily baseflow (15 mm). Groundwater storage declined at a rate of 5 mm/y due to land use impacts and this was offset by a net addition of 2 mm/y by hydrological structures. Overall the simulations suggest that the land use change impacts on streamflow are an order of magnitude larger than the impact of hydrological structures and about 2.5 time higher in terms of groundwater impacts. The total irrigation requirement, which is met by groundwater extraction, was completely met by recharge during the wet years. During the remainder of the time, (dry and normal years), the irrigation requirement was met from a combination of recharge and existing groundwater storage (50% during dry years and 30% during normal years). Overall this is leading to moderate and unsustainable declines in groundwater over time. Finally, to examine the relative impacts of potential future land and water management changes and climate change on the catchment hydrologic cycle and its sustainability, a scenario analysis was undertaken. Providing REgional Climates for Impacts Studies – a Regional Climate Model (PRECIS RCM) future climate data was used to analyse the impact of future climate changes on streamflow and groundwater storage of HS catchment. The water storage capacity of large village drinking water storage tanks and naturally formed lakes were assumed to increase by 50% by 2020 and then remain the same until the end of the century (2098). This reflects a program referred to as Mission Kakateeya, which started in 2015 in Telangana State to rejuvenate or desilt existing village water tanks to increase the capture of rainwater over the next five years, i.e by 2020. The irrigated area in the catchment was assumed to increase at the rate of 100 km2 for every 30 years by assuming that the government of Telangana would continue to subsidise farmers, whereas past growth rates have been higher (1990-2000: 85 km2; 2000-2010: 95 km2, an average of 90 km2). Irrigation is assumed to be supported by groundwater alone. Given that the HS catchment falls in a drought prone area of India, it was also assumed that the watershed development program would continue in the future, and therefore that the water storage capacity of small watershed structures would continue to increase at a constant rate over the study period. Capacity was assumed to increase 2km2 by 2040, 4km2 by 2070 and 1.7 km2 by 2098. During early-century, streamflow were predicted to reduce by an average of 49%, increases AEt by 20% and groundwater storage decreases by 3 m across the catchment compared to the baseline period. During mid-century, streamflow were predicted to decrease by 64%, AEt increases by 36% and groundwater storage declines by 7 m compared with the baseline period. During end-century, streamflow were predicted to decrease by 65%, AEt would increase by 45%, and groundwater storage could decrease by 10 m and stores will increase from -8 to 3 mm as compared to baseline period. The contribution of base flow to streamflow plays a key role in the future, it is observed that the base flow contribution is around 20-30% during low rainfall events and 60-70% during high rainfall events as compared with baseline period

A comprehensive assessment framework for attributing trends in streamflow and groundwater storage to climatic and anthropogenic changes: a case study in the typical semi‐arid catchments of Southern India

The clearest signs of hydrologic change can be observed from the trends in streamflow and groundwater levels in a catchment. During 1980-2007, significant declines in streamflow (-3.03 mm/year) and groundwater levels (-0.22 m/year) were observed in Himayat Sagar (HS) catchment, India. We examined the degree to which hydrologic changes observed in the HS catchment can be attributed to various internal and external drivers of change (climatic and anthropogenic changes). This study used an investigative approach to attribute hydrologic changes. First, it involves to develop a model and test its ability to predict hydrologic trends in a catchment that has undergone significant changes. Second, it examines the relative importance of different causes of change on the hydrologic response. The analysis was carried out using Modified SWAT, a semi-distributed rainfall-runoff model coupled with a lumped groundwater model for each sub- catchment. The model results indicated that the decline in potential evapotranspiration (PET) appears to be partially offset by a significant response to changes in rainfall. Measures that enhance recharge, such as watershed hydrological structures, have had limited success in terms of reducing impacts on the catchment-scale water balance. Groundwater storage has declined at a rate of 5 mm/y due to impact of land use changes and this was replaced by a net addition of 2 mm/y by hydrological structures. The impact of land use change on streamflow is an order of magnitude larger than the impact of hydrological structures and about is 2.5 times higher in terms of groundwater impact. Model results indicate that both exogenous and endogenous changes can have large impacts on catchment hydrology and should be considered together. The proposed comprehensive framework and approach demonstrated here is valuable in attributing trends in streamflow and groundwater levels to catchment climatic and anthropogenic changes

Fostering Κ-carrageenan Hydrogels with the Power of Natural Crosslinkers: A Comparison between Tender Coconut Water and Potassium Chloride for Antibacterial Therapy

Hydrogels have emerged as a promising solution to combat infections in various biomedical applications by acting as antibacterial drug carriers, but they lack mechanical strength and must be crosslinked before use. Herein, we investigated whether tender coconut water can be used as a natural alternative to KCl to crosslink κ-carrageenan hydrogels for antibacterial therapy. Κ-carrageenan hydrogels crosslinked with tender coconut water, KCl, and their combination were fabricated, and their morphology, chemical bonding, compressive strength, water uptake capacity, degradation resistance, and cytotoxicity were assessed. The results showed that crosslinking with tender coconut water and KCl increased the compressive strength of κ-carrageenan hydrogels by 450%, rendered an excellent water retention capacity, and degraded by just about 5% after 20 days! The scanning electron micrographs show that crosslinking with tender coconut water and KCl compacted the hydrogel morphology with narrow cracks for efficient diffusion, and such were biocompatible when tested against 3T3 cells. The infrared analysis confirmed that diclofenac sodium remained inert when introduced into the hydrogel matrices. Also, the in-vitro release behavior and antibacterial activity of the hydrogels were assessed by loading them with diclofenac sodium nanoemulsified to increase hydrophilicity, in which the release of the hydrogels crosslinked with tender coconut water and KCl was steady and sustained. Such hydrogels also showed a unique antibacterial activity against Staphylococcus aureus and Escherichia coli, with the latter much more prominent than the former. These results confirm that crosslinking with tender coconut water and KCl is a superior alternative to KCl for κ-carrageenan hydrogels

Impact of agricultural water management interventions on upstream–downstream trade-offs in the upper Cauvery catchment, southern India:a modelling study*

The Cauvery basin in southern India is experiencing transboundary issues due to increasing water demand. This study analysed water balance components and the impact of agricultural water management (AWM) interventions in the upper Cauvery catchment of the Cauvery basin. Results showed that the study catchment receives an average of 1280 mm of annual rainfall. Of this, 29% (370 mm) flows downstream, 54% (700 mm) contributes to evapotranspiration (ET) and 17% (215 mm) contributes to groundwater recharge and surface storage. Rainfall varies from 700 to 5400 mm and the Western Ghats (mountain pass) are the main source of freshwater generation. The estimated ET in different catchments ranged from 500 to 900 mm per annum. An increase in the allocation of fresh water supplied by all three reservoirs (Hemavathi, Harangi and KRS) was observed in the canal command areas, from 1450 million cubic metres (MCM) yr‾¹ in 1971–1980 to 3800 MCM yr‾¹ in 2001–2010. AWM interventions harvested 140–160 MCM (13–20 mm) of surface runoff upstream of the upper Cauvery and reduced inflow into the Krishnaraja Sagar reservoir by 2–6%. The study findings are useful for designing and planning suitable water management interventions at basin scale