Food is the essential foundation for sustainable and healthy communities. Increasing population and urbanization, limited resources, and complexities of interactions necessitate a comprehensive and in-depth understanding of the dynamics of the global trend of urbanization. The key objective of this paper is to generate new environmental, social and economic perspectives and practices that are responsive to the rapidly urbanizing agricultural food system. We used the sustainability paradigm in the context of environmental, social, and economic sustainability to outline the three transitioning states and perspectives (unconnected/silos; interconnected/linkages; and interdependent/nested/systems) for urban agricultural food systems. We sought to ferret out the key driver/response variables and their cross-scale interactions in the urbanizing food-energy-water nexus. We used a five-step qualitative analytical method to develop a conceptual model to capture the interacting variables and their responses. The complexity in the driver/response variables and their cross-scale interactions were identified. Then three hypothetical scenarios were used to represent complexity modeling: least, medium and most complex. These variables were combined with outside dimensions (e.g., innovation, stakeholders, urbanization) for selected scenarios and deconstructed using spider web and causal loop models. The urbanizing socio-ecological systems, across various spatial (local to global) and temporal scales (days to millennium) as well as smaller temporal scales (days to decades) are described. The iterative multidimensionality of the model makes clear new ways of seeing social issues and opens opportunities for policy solutions, resources and stakeholders to be brought to bear on the issues.

A simple colorimetric method has been developed for the detection of lead (Pb2+) in water samples using lipoic acidfunctionalized gold nanoparticles. The lipoic acid-functionalized gold nanoparticles are induced to aggregate in the presence of the Pb2+ which results in a change in the color of the functionalized gold nanoparticles. The change in color and the amount of Pb2+ producing the change could be monitored via UV-visible spectrophotometry. A good correlation coefficient of 0.9927 was obtained for the calibration curve of the colorimetric method. The method was applied in the determination of Pb2+ in water samples and the results compared to that of measurement carried out with Atomic Absorption Spectroscopy.

This research study focused on improving the methodology of producing dye-sensitized solar cells (DSSC) by the process of amalgamation with natural dyes. This research is done with the hope of maximizing cell efficiency and sustainable power production for mass manufacturing processes at the most economical cost. The construction of DSSC is a three-step process comprising: dye extraction, TiO 2 paste application, and solar cell structure. These important factors contribute significantly to the efficiency maximization of a dye-sensitized solar cell. This research work conducted specifically explored different ways of improving the current-voltage potential of the solar cells. The solar cell's performance in terms of efficiency and power output (voltage vs. current) was tested under an indoor room light, a halogen lamp and direct sunlight. The experimental results show that the dye extract from Green Cabbage produced the greatest photoelectric conversion efficiency (η) of up to 0.1%, an open-circuit voltage (V OC) of 532 mV, and a short-circuit current density (Jsc) of 1.2 mA/cm 2 .

Coal-fired power plants emit greenhouse gases (GHG) that cause global warming. Coal, being one of the most important fossil fuel, emits three times as much GHG as natural gas. The combustion of coal (fossil fuels at large) discharge different kinds of chemical substances that affect ecosystems and human health. Some of the most important by-products include Nitrous oxides, Sulfur oxides, Carbon dioxide, Fly ash and Mercury. Various studies have confirmed that fly ash contains high levels of carcinogens causing more incidences of cancer, albeit data on ecosystems health is scanty and little is understood. The Author designed a greenhouse study to investigate the effects of coal by-products on the health of immediate ecosystems by growing tomatoes in potted soils collected from two coal-fired power plants. The first site (Chalk Point generating station), is located in Prince George's County (MD) while the second one (Brandon Shore generating Station) is located in Anne Arundel County near Curtis Bay (MD). Three replicate samples were taken within 1 mile and 4 miles radius of these coal-fired power plants. Measurements were made on the soils physico-chemical (pH, soil texture) and plant morphological (leaf-area-index, color, stalk diameter and height) characteristics. Results of the analysis show that plants growing in close proximity to the coal-fired power plants exhibit a very low leaf-area-index, stunted growth and overall low performance. The study concluded that coal-fired power plants do exert undesirable ecological impacts and in the long-run can have a detrimental effect on the health of ecosystems.

Micro and nanoplastics, pervasive environmental pollutants, pose significant threats to ecosystems and human health, necessitating urgent research and innovative solutions. Several research groups have investigated the uptake of synthetic microplastics (MPs) and nanoplastics (NPs) using various model organisms. We investigated the uptake and the growth inhibitory effect of polystyrene (PS) and polymethacrylate (PMA)-based MPs and NPs in Tetrahymena pyriformis. Carboxyl-modified PS-MPs showed a greater growth inhibitory effect than amine-modified PS-MPs and PMA-based MPs. We also studied the impact of these particles on the transcriptomics of T. pyriformis and observed that PS-MPs directly impact various signaling pathways related to oxidative stress. PMA-based MPs showed differential expressions of signaling pathways related to cancer and some related to oxidative stress. Using a fluorescent probe, we measured the reactive oxygen species (ROS) generated by carboxyl-modified PS-MPs and PMA-MPs and observed that PS-MPs generated greater ROS than PMA-MPs. This study suggests that it is important to understand the type and the nature of chemical modification of various MPs and the specific signaling pathways in particular oxidative-related pathways they target on diverse groups of organisms, as this will provide key information related to the effect of various modified MPs and NPs on human health.