Deposition and Characterisation of SnS Thin Films for Application in Photovoltaic Solar Cell Devices

Thin films of SnS have been deposited onto heated glass substrates using the thermal evaporation method and the chemical and physical properties of the layers determined and correlated to the deposition conditions and to post-deposition heat treatments. In particular scanning electron microscopy, energy dispersive X-ray analysis, X-ray di.ractrometry and Raman studies were used to determine the material properties, transmittance and reflectance spectroscopy to determine the optical constants and 4-probe and van der Pauw measurements to determine the electrical properties. The results indicate that for a wide range of deposition conditions it is possible to produce high quality layers of SnS that are free from pin-holes and cracks, that are made of densely packed grains, and that adhere strongly to the substrate. For substrate temperatures between 280°C to 360°C it is possible to produce single phase SnS layers. The energy bandgap of these layers was in the range 1.3eV to 1.35eV, was direct, and had an optical absorption coefficient α > 105 cm-1 for photons with energies greater than the energy bandgap. The electrical properties indicate that all the layers are p-conductivity type with resistivities in the range 40Ωcm to 100Ωcm. Solar cell devices were fabricated in the superstrate and substrate configurations using n-type cadmium sulphide (CdS) and zinc indium diselenide (ZIS) buffer layers to partner the p-type SnS. The devices were investigated by measuring the I-V characteristics in the dark, to determine the predominant conduction mechanisms, the I-V characteristics under illumination to determine the open-circuit voltage V, the short circuit current density Jsc, the fill factor FF and solar conversion efficiency of the devices, C-V studies to determine the doping profile in the SnS and the built-in voltage at the junction and spectral response measurements to determine the minority carrier diffusion length in the p-SnS. Devices made with CdS as the n-type partner had a high density of interface states (1.36 x 1011 F C-1cm-2) with low photovoltaic parameters and a negative band offset of -0.36 eV obtained (as measured using x-ray photoelectron spectroscopy). The best devices made were substrate configuration solar cells in which the back contact on glass was molybdenum and the bu.er layer was ZIS. These devices have Voc = 472 mV, Jsc = 16.1 mA/cm2 , FF = 0.38 and a solar conversion efficiency of 2.9%. This is a world record efficiency for SnS-based solar cells at the time of submission of this PhD thesis

Technical Training Skills Needs of Youth for Sustainable Job Security in Rice Production in Ebonyi State, Nigeria

The study identifies technical training skills needs of youth for sustainable job security in rice production in Ebonyi State, Nigeria. This study was carried out in secondary schools in three educational zones in Ebonyi State, Nigeria. Ebonyi state is one of the states in the southeast geopolitical zone in Nigeria. Descriptive survey design was adopted for this study. Target population was 317 made up of 300 registered rice farmers, 5 Agricultural education lecturers and 12 Agricultural extension agents. Sample for the study was 267. Simple random sampling technique was used in selecting the respondents. Four research questions guided the study. The instrument used for data collection was structured questionnaire developed by the researchers. Three experts validate the instrument, one expert from Measurement and Evaluation, Department of science education and two from Agricultural education option, in Technology Vocational Education in the same Ebonyi State University Abakaliki. The Cronbach Alpha reliability coefficient was used to test the internal consistency of the item statement and the reliability co-efficient of 0.78 was found. Instruments were administered to respondents. Data collected were analyzed using mean and standard deviation,  result revealed that  table 2, 3 and 4 all the items statement were needed with 2.50 and above while table 1 item 10 and 11 statements were not needed with mean score below 2.50. Among the recommendations made was that the technical training skills identified should be used in train youth for maximum rice production in Ebonyi State. Keywords: Job Security, Needs, Sustainable, Training Skill, Youth

Hepatoprotective activity of n-hexane and ethyl acetate fractions of Sida acuta on thioacetamide induced liver injury in rats

This study investigated the hepatoprotective effects of n-hexane and ethylacetate fractions of Sida acuta against thioacetamide (TAA) induced hepatotoxicity in rats. Thirty-five adult male albino wistar rats, grouped into seven groups (n=5 each) were used. Groups A-D served as the tests, while E-G served as control. The rats were fed as discussed in the methodology. Phyto-chemical analysis of Sida acuta was done using standard methods. Acute toxicity test revealed an oral LD50 of >3000 mg/kg. Test administration was oral for 7 days prior to TAA intoxication. On the 8th day, after an 18-hour fast, TAA (200mg/kg) was injected subcutaneously to all the groups except group G (normal control). Blood samples were collected 24hrs after TAA administration to assess the liver function of the rats (ALT, AST, ALP and Albumin levels). Results revealed a significant increase in the serum levels of ALP, AST and ALT, as well as a significant decrease in the serum Albumin levels due to TAA induced liver damage. Pre-treatment with both n-hexane and ethyl acetate fractions of Sida acuta reduced the toxic effect of TAA as indicated by a decrease in the levels of previously elevated liver parameters and an increase in the level of Albumin.Keyswords: Hepatoprotective, n-Hexane, Ethyl acetate, Sida acuta, Thioacetamide, liver functio

Optimisation of Doped Antimony Sulphide (Sb2S3) Thin Films for Enhanced Device Applications

Energy scarcity is ubiquitous, and more acute in developing nations. Diversification of energy sources toward renewable energy is one of the world major approach in solving this problem. Thin film solar cells is universally recognized as one of the best way forward, thus investigation of low cost, non toxic inorganic materials for use in absorber and window layers in thin film photovoltaic solar cell devices will play a significant role in that regard. Thin films of antimony sulphide were grown using the solution growth technique. The films were doped with nickel impurities and annealed at annealing temperatures in the range 50 °C to 200 °C, with the annealing time fixed for 1 hour. The films were characterised using X-ray diffractometry to investigate the structural properties and UV-spectroscopy to investigate the optical properties, thus enabling to evaluate the optical constants (optical absorption coefficient, energy bandgap, refractive index, extinction coefficient, optical density, dielectric constants etc). The results from the structural analysis indicate that the films are mostly amorphous, and exhibited a polycrystalline form at an annealing temperature of 150 °C. The optical analysis show that the optical absorption coefficient were > 104 cm – 1, the energy bandgap was direct with values in the range 2.26 eV to 2.52 eV. The results of the optical studies (direct energy bandgap, values of the energy bandgap and low resistivity) indicate that the films will be utilised as window layers in solar cell devices and in other optoelectronic applications

Dengue virus is hyperendemic in Nigeria from 2009 to 2020: A contemporary systematic review

Backround: Data on Dengue virus (DENV) infection prevalence, geographic distribution and risk factors are necessary to direct appropriate utilization of existing and emerging control strategies. This study aimed to determine the pooled prevalence, risk factors of DENV infection and the circulating serotypes within Nigeria from January 1, 2009 to December 31, 2020. Materials and methods: Twenty-one studies out of 2,215 available articles were eligible and included for this systematic review. Relevant articles were searched, screened and included in this study according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria. The risk of bias in primary studies was assessed by Cochrane's method. Heterogeneity of pooled prevalence was calculated using the chi-square test on Cochrane's Q statistic, which was quantified by I-square values. The random-effects analyses of proportions were used to determine the pooled prevalence of DENV antibodies, antigen and RNA from eligible studies. Results: Of these, 3 studies reported co-circulation of all the 4 serotypes, while 2 separately reported co-circulation of DENV-1 &2 and DENV-1 to -3. All the antibody-based studies had significantly high heterogeneity (I2 >90%, P 0.05). The pooled prevalence of DENV IgM, IgG, RNA, NS1 and neutralizing antibodies were 16.8%, 34.7%, 7.7%, 7.7% and 0.7%, respectively. Southeast Nigeria had the highest pooled DENV-IgG seropositivity, 77.1%. Marital status, gender, educational level and occupation status, the proximity of residence to refuse dumpsite, frequent use of trousers and long sleeve shirts were significantly associated with DENV IgG seropositivity (P <0.05). Conclusion: Based on these findings, it can be inferred that Nigeria is hyperendemic for Dengue fever and needs concerted efforts to control its spread within and outside the country

Humoral immunological kinetics of severe acute respiratory syndrome coronavirus 2 infection and diagnostic performance of serological assays for coronavirus disease 2019: an analysis of global reports

As the coronavirus disease 2019 (COVID-19) pandemic continues to rise and second waves are reported in some countries, serological test kits and strips are being considered to scale up an adequate laboratory response. This study provides an update on the kinetics of humoral immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and performance characteristics of serological protocols (lateral flow assay [LFA], chemiluminescence immunoassay [CLIA] and ELISA) used for evaluations of recent and past SARS-CoV-2 infection. A thorough and comprehensive review of suitable and eligible full-text articles was performed on PubMed, Scopus, Web of Science, Wordometer and medRxiv from 10 January to 16 July 2020. These articles were searched using the Medical Subject Headings terms 'COVID-19', 'Serological assay', 'Laboratory Diagnosis', 'Performance characteristics', 'POCT', 'LFA', 'CLIA', 'ELISA' and 'SARS-CoV-2'. Data from original research articles on SARS-CoV-2 antibody detection >= second day postinfection were included in this study. In total, there were 7938 published articles on humoral immune response and laboratory diagnosis of COVID-19. Of these, 74 were included in this study. The detection, peak and decline period of blood anti-SARS-CoV-2 IgM, IgG and total antibodies for point-of-care testing (POCT), ELISA and CLIA vary widely. The most promising of these assays for POCT detected anti-SARS-CoV-2 at day 3 postinfection and peaked on the 15th day; ELISA products detected anti-SARS-CoV-2 IgM and IgG at days 2 and 6 then peaked on the eighth day; and the most promising CLIA product detected anti-SARS-CoV-2 at day 1 and peaked on the 30th day. The most promising LFA, ELISA and CLIA that had the best performance characteristics were those targeting total SARS-CoV-2 antibodies followed by those targeting anti-SARS-CoV-2 IgG then IgM. Essentially, the CLIA-based SARS-CoV-2 tests had the best performance characteristics, followed by ELISA then POCT. Given the varied performance characteristics of all the serological assays, there is a need to continuously improve their detection thresholds, as well as to monitor and re-evaluate their performances to assure their significance and applicability for COVID-19 clinical and epidemiological purposes

New Media and Social Movements. How the Indigenous People of Biafra Movement Has Used the Internet to Mobilise for an Independent Biafran State

This study has examined the implications of the internet for the IPOB movement, focusing on the extent to which it has empowered the movement to engage in collective action mobilisation, enhance identity construction, framing and discourses for an independent Biafran state against multiple forms of state repressions. The thesis adopted a flexible approach that incorporated three level analysis including a macro-level analysis, which looked at the socio political and institutional environment; a meso-level, which examined the organisational infrastructure; and a micro-level exploring how the social movement made sense of their reality. The thesis addresses the debate between technology and society, and between the agency and political opportunity structures in Nigeria. It discussed the radical and agnostic democratic potential of the internet for African social movements and the dialectic between Biafra activism and the socio-political rootedness of Nigerian democracy. This approach allowed for providing analogies and new perspectives from the research and interpreting implications of human action. The thesis has found inconsistent, sometimes contradicting, data on the implication of internet technology for the IPOB movement. While there is some clear and robust evidence suggesting that new media technology has enhanced the movement's capabilities to organise, coordinate and mobilise for Biafran cause on many levels. The study reveals some severe limitations in the appropriation of internet technology in IPOB’s collective action objectives. The implication of the findings is discussed

Effect of Deposition Time on the Optical Properties of Cadmium Sulphide Thin Films

In this study, we report on the effect of deposition time on the optical properties of SILAR (successive ionic layer and reaction) grown cadmium sulphide thin films. The films were characterised using a UV spectrophotometer to investigate the absorbance, transmittance, and reflectance versus wavelength measurements, to enable the determination of some important optical constants. The results show that deposition time had a strong influence on the properties of the films. The optical constants such as the energy bandgap, refractive index, extinction coefficient and the dielectric constants were found to vary with the deposition time. In particular, the energy bandgap was found to increase with an increase in the deposition time. The refractive index was in the range 1.2 to 1.8 while the extinction coefficient varied between 0.010 to 0.038. The values of the refractive index and extinction coefficient were slightly higher at the lower deposition time

New Media and Social Movements. How the Indigenous People of Biafra Movement Has Used the Internet to Mobilise for an Independent Biafran State

This study has examined the implications of the internet for the IPOB movement, focusing on the extent to which it has empowered the movement to engage in collective action mobilisation, enhance identity construction, framing and discourses for an independent Biafran state against multiple forms of state repressions. The thesis adopted a flexible approach that incorporated three level analysis including a macro-level analysis, which looked at the socio political and institutional environment; a meso-level, which examined the organisational infrastructure; and a micro-level exploring how the social movement made sense of their reality. The thesis addresses the debate between technology and society, and between the agency and political opportunity structures in Nigeria. It discussed the radical and agnostic democratic potential of the internet for African social movements and the dialectic between Biafra activism and the socio-political rootedness of Nigerian democracy. This approach allowed for providing analogies and new perspectives from the research and interpreting implications of human action. The thesis has found inconsistent, sometimes contradicting, data on the implication of internet technology for the IPOB movement. While there is some clear and robust evidence suggesting that new media technology has enhanced the movement's capabilities to organise, coordinate and mobilise for Biafran cause on many levels. The study reveals some severe limitations in the appropriation of internet technology in IPOB’s collective action objectives. The implication of the findings is discussed