Advances in Perovskite-Based Solar Cells

The increase in energy demand due to increase in population and reduction of fossil fuels has led to the search of alternative energy sources. Solar energy, which is an alternative source of energy, has been in the fore front of this research. Various methods of converting solar energy into electricity has been attained by silicon solar cells, thin film solar cells, dye sensitized solar cells and perovskite solar cells. Unlike dye sensitized solar cells, perovskite solar cells based on lead halide perovskite or organic-inorganic halide perovskite have had a significant impact on photovoltaic devices. A power conversion efficiency of approximately 20.1% has been attained by perovskite solar cells compared to organic solar cells. Also, several fabrication techniques, hole and electron transport materials have been developed for high performance. Although, some issues need to be addressed before commercialization is possible. Issues like stability of the cells under moisture and temperature. In this review, fundamental aspects of the perovskite device and recent breakthroughs are illustrate

Archetypes of remnant West African forest patches, their main characteristics and geographical distribution

Remnant West African forest patches provide crucial ecosystem functions and services while contributing to sustaining the livelihoods of vast numbers of people. The vast majority lie outside of protected areas, although relatively few are managed as sacred forests, which limits their access and use. This lack of protection, together with a growing demand for arable land and forest resources, have accentuated their fragmentation, degradation, and deforestation. There is therefore an urgent need to generate knowledge on their social-ecological characteristics and change pressures to support their conservation. This study investigates what are i) the main biophysical and social-ecological characteristics of remnant forest patches, and ii) the potential change pressures and drivers. Within this scope, we apply archetype analysis to discern processes affecting remnant forest patches. Biophysical and socio-ecological indicators were selected from a published dataset via expert consultation, and nine archetypes were developed by applying a cluster analysis. Evaluating the results in relation to ecoregions and landscape features using high resolution imagery, we identify common underlying social-ecological change pressures and characteristics. The most common archetype (2) is characterized by being close to protected areas and having a low average annual precipitation and cluster along the northern fringe of the study area. The second most common archetype (5) is characterized by lying in highly disturbed landscapes, having undergone biomass losses, and widely distributed throughout central and western Nigeria. Patches of archetype 8 found predominantly in mangrove and swamp forests, exhibit positive above-ground biomass changes and greening trends; we propose that these vegetation changes could benefit conservation measures and carbon sequestration programs. In contrast, archetype 10 patches show both forest and biomass losses and gains and are often encompass fragmented forests in urban/arable landscapes. Identifying such common patterns of anthropogenic and ecological change provides a means of prioritizing regionalized strategies for their conservation and sustainable use

A Remote Sensing-Based Inventory of West Africa Tropical Forest Patches: A Basis for Enhancing Their Conservation and Sustainable Use

The rate of tropical deforestation is increasing globally, and the fragmentation of remaining forests is particularly high in arable landscapes of West Africa. As such, there is an urgent need to map and monitor these remnant forest patches/fragments and so identify their multiple benefits and values. Indeed, recognizing their existence will help ensure their continued provision of ecosystem services while facilitating their conservation and sustainable use. The aim of this study is therefore to inventory and characterise the current extent and change of remnant forest patches of West Africa, using multi-source remote sensing products, time-series analyses, and ancillary datasets. Specifically, we collate and analyse descriptive and change metrics to provide estimates of fragment size, age, biophysical conditions, and relation to social-ecological change drivers, which together provide novel insights into forest fragment change dynamics for over four decades. We map forests patches outside protected areas with a tree cover ≥30%, a tree height of ≥5 m, an area ≥1 km2 and ≤10 km2. Appended to each patch are descriptive and change dynamics attributes. We find that most fragments are small, secondary forest patches and these cumulatively underwent the most forest loss. However, on average, larger patches experience more loss than smaller ones, suggesting that small patches persist in the landscape. Primary forest patches are scarce and underwent fewer losses, as they may be less accessible. In 1975 most patches were mapped as secondary, degraded forests, savanna, woodland, and mangrove, and relatively few comprised cropland, settlements, and agriculture, suggesting that new forest patches rarely emerged from arable land over the past 45 years (1975–2020), but rather are remnants of previously forested landscapes. Greening is widespread in larger secondary fragments possibly due to regrowth from land abandonment and migration to urban areas. Forest loss and gain are greater across fragments lying in more modified landscapes of secondary forests, while forest loss increases with distance to roads. Finally, larger forest patches harbour a denser tree cover and higher trees as they may be less impacted by human pressures. The number and extent of West African forest patches are expected to further decline, with a concurrent heightening of forest fragmentation and accompanying edge effects. Lacking any conservation status, and subject to increasing extractive demands, their protection and sustainable use is imperative

A Geochemical Analytical Scheme for the Appraisal of Partitioning and Mobility of Major elements in Weathered Dry Disposed Coal Fly Ash

South Africa is endowed with significant deposits of coal which is utilized in electricity generation to meet the nation’s energy demand. A large volume of waste solid residue from the combustion of pulverized feed coal in power stations is dry disposed in stock piles or dumps. Chemical interactions of dry disposed fly ash with ingressed CO2 from the atmosphere and infiltrating rain water would cause dissolution of the soluble components in the fly ash matrix. Chemical partitioning and mobility of major elements in samples from cores drilled into serially stacked weathered dry disposed fly ash were investigated using a modified five steps sequential extraction scheme. A total acid digestion was carried out on the original ash core samples prior to extraction to validate the extraction procedure. The geochemical distribution of the investigated major elements in 59 drilled core samples was determined by x-ray fluorescence and inductively coupled plasma mass spectrometry. The relationship between SiO2 and chemical index of alteration (CIA) showed 8 year and 20-year-old core samples have a moderate to high degree of weathering. Conversely, 1-year-old cores samples showed characteristics between low and moderate-high degrees of weathering. A cluster and discriminant analysis of the major elements was also able to reveal the subtle chemical alteration differences of the core samples. Functional analysis revealed the disparities in the dissolution patterns of major soluble components in the matrix of the drilled core samples. Modified sequential extractions revealed high concentration of the major species in the leachates for every mineralogical fraction; although the bulk of the major elements are locked up in the insoluble phase of the core samples (i.e. residual fraction) which would not be released under normal environmental conditions. It is noteworthy that the concentration of major elements in the labile fractions (water soluble + exchangeable + carbonate) was high and this has implications for the long-term durability of residual mineral phases. Relative enrichment and depletion trends of major elements are promoted by heterogeneity in the ash dump (i.e. moisture content), gradual reduction of pore water pH and continuous brine and water irrigation.Key words: Coal fly ash; Weathering; Sequential extraction scheme; Cluster analysis; Factor Analysis

COMPARATIVE STUDY OF CORROSION PERFORMANCE OF ALUMINIUM- ZINC COATED, GALVANIZED AND ELECTROPLATED STEELS IN TOMATO JUICE

Metallic materials are given prominent considerations in agro-based machinery especially in fruit juice processing, storage and use as disposable cans. Such metallic materials include Electroplated Steel (ES), Galvanized Steel (GS) and Aluminum-zinc coated steel (Aluzinc). This study evaluated the corrosion performance of Aluzinc, GS and ES in tomato juice. The medium was chosen due to its social and economic importance. Samples of Aluzinc, GS and ES were prepared by cutting into 3 x 3 cm2 from 1 mm thick plate. Three of each of the prepared samples were used for Potentiostatic Polarization Experiments (PPE) while 18 samples each were used for Weight Loss Method (WLM). Each of the prepared samples for WLM was cleaned, weighed and immersed in the media for 30 days. The samples were removed at the end of immersion, cleaned and reweighed. The results obtained for the corrosion rates in mm/y using PPE in tomato juices were 0.0061, 0.0065 and 0.0148 for Aluzinc, GS and ES respectively. The measured pH values for the media ranged from 4.1 to 8.3. Aluzinc had the lowest corrosion rate in tomato juice followed by GS and ES after 30 days of immersion using WLM

Short-duration exposure to 2.45 GHz microwave radiation induces DNA damage in Sprague Dawley rat's reproductive systems

The genotoxic effects of 2.45 GHz microwave (MW) radiation on the testis and ovary of Sprague Dawley rats was investigated. The animals were exposed to varying levels of specific absorption rat

Evaluation of a new, perforated heat flux plate design

Accurate measurement of heat flux is essential to optimize structural and process design and to improve understanding of energy transfer in natural systems. Laboratory and field experiments evaluated the performance of a new, perforated heat flux plate designed to reduce flow distortion for environmental applications. Laboratory tests involving dry and saturated sand showed that performance of the new CAPTEC plate is comparable to a solid, standard REBS plate. Very low thermal gradients may have however led to poor performance of the CAPTEC plate in saturated sand. Water infiltration and redistribution experiments using clayey and sandy soils showed an apparent reduced disruption of liquid water and vapour in the soil surrounding the CAPTEC plate as compared to solid Hukseflux and standard REBS plates. Surface area of REBS plate, though smaller than that of CAPTEC, did not lead to any significantly improved evaporation, due to perforations on CAPTEC plate. Field tests in a loam soil indicated that the CAPTEC plates were durable and produced daily total flux values within ~ 0.15 MJ m− 2 of independent estimates

Progress on Organic Solar Cells: A Short Review

Thin film organic solar cells have emerged as a replacement to inorganic solar cells based on silicon. Organic solar cells offer several advantages compared to silicon-based devices. In the last 10 years, concentrated research attempts towards accomplishing the mandatory power conversion efficiency of 10 % and environmental stability of the device still remain a main challenge. In order to influence the efficiency, polymers are frequently utilized to fabricate the absorber and buffer layers. Also, binary and tenary polymer blends have been devised to influence the performance in micro/nanostructures. In addition, the advantages of organic solar cells for realistic application, and potential solutions are also considered

Cost of Corrosion of Metallic Products in Federal University of Agriculture, Abeokuta

The cost of corrosion has been increasing drastically due to the degradation of the metallic materials. This study was carried out to estimate the “Cost of Corrosion of Metallic Products in Federal University of Agriculture, Abeokuta (FUNAAB)”. Questionnaires were administered and interviews were also conducted to gather necessary information. The cost of corrosion from 2013-2015 was estimated and analysed with the aid of engineering economy method and statistical analysis method. For the cost of corrosion prevention methods, cleaning gave the highest cost contribution (69%), followed by the use of oil (30%), use of grease (1%), and painting gave zero percent of the total cost. While on the cost of corrosion maintenance methods, repair gave the highest cost contributions (66%), and prevention gave (34%) of the total cost. The overall cost of corrosion from (2013-2015) gave an upward trend, but a downward trend in future value and the annualized value. While the forecast cost from (2013-2016) at (95%) confidence level and (5%) significance level gave an upward trend. The present value, future value, and annualized value from (2013-2016) increased by (66%, 43%, and 75%) respectively. The total cost and the total annualized value of corrosion from (2013-2015) were estimated to be N 166,955,641 and N 93,791,024, and with the forecast (2013-2016) were found to be N 277,650,388 and N 163,672,460 respectively. Under the corrosion prevention methods and corrosion maintenance methods, cleaning and repair gave highest cost contribution respectively. Corrosion prevention methods need to be added to bring down the repair cost of those facilities for saving cost

Biological sample donation and informed consent for neurobiobanking: Evidence from a community survey in Ghana and Nigeria

Copyright: \ua9 2022 Singh et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Introduction Genomic research and neurobiobanking are expanding globally. Empirical evidence on the level of awareness and willingness to donate/share biological samples towards the expansion of neurobiobanking in sub-Saharan Africa is lacking. Aims To ascertain the awareness, perspectives and predictors regarding biological sample donation, sharing and informed consent preferences among community members in Ghana and Nigeria. Methods A questionnaire cross-sectional survey was conducted among randomly selected community members from seven communities in Ghana and Nigeria. Results Of the 1015 respondents with mean age 39.3 years (SD 19.5), about a third had heard of blood donation (37.2%, M: 42.4%, F: 32.0%, p = 0.001) and a quarter were aware of blood sample storage for research (24.5%; M: 29.7%, F: 19.4%, p = 0.151). Two out of ten were willing to donate brain after death (18.8%, M: 22.6%, F: 15.0%, p<0.001). Main reasons for unwillingness to donate brain were; to go back to God complete (46.6%) and lack of knowledge related to brain donation (32.7%). Only a third of the participants were aware of informed consent (31.7%; M: 35.9%, F: 27.5%, p<0.001). Predictors of positive attitude towards biobanking and informed consent were being married, tertiary level education, student status, and belonging to select ethnic groups. Conclusion There is a greater need for research attention in the area of brain banking and informed consent. Improved context-sensitive public education on neurobiobanking and informed consent, in line with the sociocultural diversities, is recommended within the African sub region