Development and Characterisation of a Whole Hybrid Sol-Gel Optofluidic Platform for Biosensing Applications

This work outlines, for the first time, the fabrication of a whole hybrid sol-gel optofluidic platform by integrating a microfluidic biosensor platform with optical waveguides employing a standard photolithography process. To demonstrate the suitability of this new hybrid sol-gel optofluidic platform, optical and bio-sensing proof-of-concepts are proposed. A photoreactive hybrid sol-gel material composed of a photopolymerisable organically modified silicon alkoxide and a transition metal complex was prepared and used as the fabrication material for the entire optofluidic platform, including the optical waveguides, the sensing areas, and the microfluidic device. The most suitable sol-gel materials chosen for the fabrication of the cladding and core of the waveguides showed a RIC of 3.5 × 10-3 and gave thicknesses between 5.5 and 7 μm. The material was optimised to simultaneously meet the photoreactive properties required for the photolithography fabrication process and the optical properties needed for the effective optical operability of the microstructured waveguides at 532 and 633 nm with an integrated microfluidic device. The optical proof-of-concept was performed using a fluorescent dye (Atto 633) and recording its optical responses while irradiated with a suitable optical excitation. The biosensing capability of the platform was assessed using a polyclonal primary IgG mouse antibody and a fluorescent labelled secondary IgG anti-mouse antibody. A limit of detection (LOD) of 50 ug/mL was achieved. A correlation between the concentration of the dye and the emission fluorescence was evidenced, thus clearly demonstrating the feasibility of the proposed hybrid sol-gel optofluidic platform concept. The successful integration and operability of optical and microfluidic components in the same optofluidic platform is a novel concept, particularly where the sol-gel fabrication material is concerned

Effects of varying organic matter content on the development of green roof vegetation: a six year experiment

Green roofs can potentially be used to tackle a variety of environmental problems, and can be used as development mitigation for the loss of ground-based habitats. Brown (biodiversity) roofs are a type of green roof designed to imitate brownfield habitat, but the best way of engineering these habitats requires more research. We tested the effects of altering organic matter content on the development of vegetation assemblages of experimental brown (biodiversity) roof mesocosms. Three mulch treatments were tested: (1) Sandy loam, where 10mm of sandy loam mulch (about 3% organic matter by dry weight) was added to 100mm of recycled aggregate; (2) Compost, where the mulch also contained some garden compost (about 6% organic matter by dry weight); and (3) No mulch, where no mulch was added. Mesocosms were seeded with a wildflower mix that included some Sedum acre, and vegetation development was investigated over a six-year period. Species richness, assemblage character, number of plants able to seed, and above-ground plant biomass were measured. Drought disturbance was an important control on plant assemblages in all mulch treatments, but there were significant treatment response interactions. The more productive Compost treatment was associated with larger plant coverage and diversity before the occurrence of a sequence of drought disturbances, but was more strongly negatively affected by the disturbances than the two less productive treatments. We suggest that this was due to the over-production of plant biomass in the more productive treatment, which made the plants more vulnerable to the effects of drought disturbance, leading to a kind of 'boom-bust' assemblage dynamic. The 'ideal' amount of added organic matter for these green roof systems was very low, but other types of green roof that have a larger water holding capacity, and/or more drought resistant plant floras, will likely require more organic matter or fertiliser. Nonetheless, nutrient-supported productivity in green roof systems should be kept low in order to avoid boom-bust plant assemblage dynamics. Research into the best way of engineering green roof habitats should take place over a long enough multi-year time period to include the effects of temporally infrequent disturbances

The influence of substrate and vegetation configuration on green roof hydrological performance

A four-year record of rainfall and runoff data from nine different extensive (80 mm substrate) green roof test beds has been analysed to establish the extent to which the substrate composition and vegetation treatment affect hydrological performance. The test beds incorporated three different substrate components with different porosity and moisture retention characteristics, and three different vegetation treatments (Sedum, Meadow Flower and unvegetated). Consistent differences were observed, with the vegetated beds showing higher levels of rainfall retention and better detention compared with unvegetated beds. The seasonal Meadow Flower beds had similar hydrological performance to Sedum-vegetated beds. There was a 27% performance reduction in annual volumetric retention attributable to differences in substrate and vegetation. The beds with the most porous/permeable substrates showed the lowest levels of both retention and detention. As with previous studies, retention efficiency in all nine beds showed a strong dependency on rainfall depth (P), with retention typically >80% for events where P < 10 mm, but significantly lower when P > 10 mm. The effects of vegetation and substrate were most evident for rainfall events where P > 10 mm, with the mean per-event retention varying between beds from 26.8% to 61.8%. On average, the test beds were able to retain the first 5 mm of rainfall in 65% of events where P > 5 mm, although this ranged from 29.4% to 70.6% of events depending on configuration. In terms of detention, all but one of the test beds could achieve runoff control to a green field runoff equivalent of 2 l/s/ha for more than 75% of events. Detention was also characterised via the calibration of a reservoir-routing modelthatlinked net rainfall to the measured runoff response. The parameter values identified here – when combined with a suitable evapotranspiration/retention model – provide a generic mechanism for predicting the runoff response to a time-series or design rainfall for any unmonitored system with comparable components, permitting comparison against local regulatory requirements

Attalea Phalerata and Biodiesel; Potential for Local and Regional Sustainabilty

OCN 499 - Undergraduate Thesi

Enhanced ethanol sensing performance of gel calcined Cd-Sn oxide nanocomposites

Cd-Sn oxide nanocomposite powders were synthesized by a facile gel calcination method, starting from precursor sol having Cd: Sn ratio as 2: 1. The powders were characterized in terms of their phase formation behaviour and morphological features using X-ray diffractometer, FTIR, UV-visible spectra and FESEM analyses. Sensor fabricated from nanocomposite calcined at 1050 degrees C exhibited excellent ethanol sensing performance, similar to 86 % for 50 ppm ethanol vapour. It also revealed quite a good sensitivity at concentration down to 5 ppm vapour. Sensors were quite stable and selective towards ethanol vapour. A possible mechanism for enhanced performance due to formation of preferential perovskite cadmium stannite phase has been discussed

Nutrient Management Practices on Growth and Yield of Finger Millet Influcened by Different Factors

A field experiment was conducted during Rabi season of 2022-23 in field no new plot 1 at South farm of Karunya Institute of Technology and Sciences, Coimbatore. This study was conducted to assess the growth and yield of finger millet using nutrient management practices. The treatment consists of seven different parameters with control. Results revealed that growth parameters, yield attributes, yield of finger millet were significantly influenced by different treatments of nutrient management. In finger millet, plant height at 90 DAS, LAI at 60 DAS and dry matter accumulation per m2 at harvest were maximum with 125% seed rate and 100% N through vermicompost. Yield attributes namely, effective tillers per m2, number of fingers per ear, ear weight, test weight, number of grains per ear, grain yield and straw yield of finger millet were also recorded maximum in the same treatment

Use of a nitrification inhibitor reduces nitrous oxide (N2O) emissions from compacted grassland with different soil textures and climatic conditions

Grassland accounts for 70 % of the global agricultural area. Grassland amended with N fertiliser, although increasing productivity, encourages the emission of the greenhouse gas nitrous oxide (N2O). Soil compaction can result in impeded water movement and the development of anaerobic conditions that favour N2O production and emissions from denitrification. Soil compaction has become more prevalent in grassland with the use of increasingly heavy machinery and the extension of seasonal animal grazing periods, especially when soil moisture is high; close to field capacity. The effect of a nitrification inhibitor - dicyandiamide (DCD) on emissions of N2O from grassland moderately compacted from animal trampling or a tractor were investigated at two experimental field sites in the UK; a silt clay loam soil in a wet climate (SRUC) and a sandy loam in a drier climate (HAU). Compaction treatments repeated annually over three years (2011–2013) gave an overall increase in soil bulk density for the tractor compaction and animal trampling at both sites but to different degrees related to soil texture. Cumulative N2O emissions from tractor compaction for both SRUC and HAU were significantly greater than from the uncompacted control over the three years, with changing climate, soil texture and soil pH influencing the magnitude of N2O emissions. The use of DCD decreased cumulative N2O emissions at both sites, with the reduction greatest under tractor compaction, especially for the drier, sandier soil with the greater porosity. DCD appeared to decrease soil nitrate (NO3−) concentrations and decreased potential NO3− losses from leaching and run-off. Extrapolating from these data, the presence of moderate compaction, as identified in grasslands in England and Wales, could result in an estimated annual increase in N2O emissions of between 0.10 and 0.78 Mt of N2O, but these emissions could be reduced by up to 16 % and 51 % through the use of DCD, depending on compaction depth and soil texture. Although no yield increases were seen from the use of the DCD at both sites, N2O emissions were reduced

A systematic review of how social connectedness impacts associations between racism and discrimination on health outcomes

Racial discrimination is a well-known risk factor of racial disparities in health. While progress has been made in identifying multiple levels through which racism and racial discrimination influences health, less is known about social factors that may buffer racism\u27s associations with health. We conducted a systematic review of the literature with a specific focus on social connectedness, racism, and health; retrieving studies conducted in the United States published between January 1, 2012 and July 30, 2022, in peer-reviewed journals. Of the 787 articles screened, 32 were selected for full-text synthesis. Most studies (72%) were individual-level, cross-sectional, and among community/neighborhood, school, or university samples. Studies had good methodological rigor and low risk of bias. Measures of racism and racial discrimination varied. Discrimination scales included unfair treatment due to race, schedule of racist events, experiences of lifetime discrimination, and everyday discrimination. Measures of social connectedness (or disconnectedness) varied. Social connectedness constructs included social isolation, loneliness, and social support. Mental health was the most frequently examined outcome (75%). Effect modification was used in 56% of studies and mediation in 34% of studies. In 81% of studies, at least one aspect of social connectedness significantly buffered or mediated the associations between racism and health. Negative health associations were often weaker among people with higher social connectedness. Social connectedness is an important buffering mechanism to mitigate the associations between racial discrimination and health. In future studies, harmonizing metrics of social connectedness and racial discrimination can strengthen causal claims to inform interventions