Remarkable attention has been committed to the recently discovered cost effective and solution processable lead-free organic-inorganic halide perovskite solar cells. Recent studies have reported that, within five years, the reported efficiency has reached 9.0%, which makes them an extremely promising and fast developing candidate to compete with conventional lead-based perovskite solar cells. The major challenge associated with the conventional perovskite solar cells is the toxic nature of lead (Pb) used in the active layer of perovskite material. If lead continues to be used in fabricating solar cells, negative health impacts will result in the environment due to the toxicity of lead. Alternatively, lead free perovskite solar cells could give a safe way by substituting low-cost, abundant and non toxic material. This review focuses on formability of lead-free organic-inorganic halide perovskite, alternative metal cations candidates to replace lead (Pb), and possible substitutions of organic cations, as well as halide anions in the lead-free organic-inorganic halide perovskite architecture. Furthermore, the review gives highlights on the impact of organic cations, metal cations and inorganic anions on stability and the overall performance of lead free perovskite solar cells.

The various efforts of the Federal Government and its agencies together with international institutions at integrating the Almajiri education into contemporary education in Nigeria or mainstreaming the Almajiri system into the nation’s educational system have not achieved the desired objectives. The failure of relevant policy makers could be traced to their solution-strategies, which did not give adequate considerations to the historical realities of the Almajiri system; to the constitutional obligation of government to provide free and compulsory basic education to its school age citizens; and to a genuine stakeholder buy-in of Almajiri school operators. Using a doctrinal research methodology that leaned more on official narrative, institutional publications as well as Internet resources and online blogs, the paper looked at Almajiri concept, reviewed the legal framework underpinning basic education rights in Nigeria, and explored the various attempts at mainstreaming the Almajiri system. The paper discovered that the solution-strategies to deal with the Almajiri challenge are premised on a jaundiced notion of the Almajiri system, which is commonly viewed as a source of terrorists and criminal gangs recruitments, and the underestimation of the capacity of Almajiri school operators to lead the process. The paper found that the risk analyses of the solution strategies were not adequate and comprehensive enough with the attendant consequence of increased suspicion between the government and Almajiri school operators. The paper therefore recommended a partnership arrangement built on mutual respect among the three stakeholders, namely, the government, the Almajiri school operators and the Almajiri parents as well as a partnership on the basis of shared responsibilities, shared resources and shared rewards under which the operators or their immediate communities will take a commanding heights in the operation and management of the Almajiri schools. This type of arrangement is a good candidate for Pro-Poor Public Private Partnership (PPPPP), which is commonly used in many jurisdictions to serve the neglected part of the populations. In this respect, the paper recommends the Charter School model, which the United States established to cater for the educationally underserved and neglected among its citizens. If implemented, the twin incidences of out-of-school children and Almajiri Street begging will greatly reduced, thereby positively impacting to the social, political and economic sectors of the Nigerian society.

Geo-electrical Resistivity Survey of BayeroUniversity Kano New Campus, Nigeria IntroductionAccess to clean water is a human right and a basic requirement for economic development. The safest source of water supply is the groundwater. Since groundwater normally has a natural protection against pollution by the covering layers, only minor water treatment is required. Detailed knowledge on the extent, hydraulic properties and vulnerability of groundwater reservoirs is necessary to enable a sustainable resource, (Kirsch, 2009). As groundwater becomes more important and a source of uncontaminated water, methods for locating good aquifers must become more efficient. Partly for this reason, geophysical methods are playing an increasingly important role in groundwater investigations. Of all surface geophysical methods, the electrical resistivity method has been the most widely used in groundwater investigations, (Walter and William, 1981).Considering the area extent of BUK New Site and the number of boreholes available in the site and even the way water is being distributed daily within the campus by the use of tankers, there is the need to carry out an investigation of this kind in order to strategize drilling of boreholes for optimal supply rather than indiscriminate water exploitation activities.Another important issue in this study is the determination of the subsurface lithology, which will help in delineating the depth to which the borehole(s) can be sunk to obtain maximum, portable and consumable water, thus determining the depth of each layer and also the need for detailed evaluation of subsurface condition to guide civil engineering activities The geology of the study area is the same as that of Kano in general. The Bayero University, Kano permanent site is underlain by the basement complex rock of the north-western Nigeria. The rock types in the area are older granites sediments and older basement (www.kanostate.net, 2011) as cited by Oritsejolonsan and Saleh (2011). TheoryThe purpose of electrical resistivity surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface. From this measurement, the true resistivity of the subsurface can be estimated. The ground resistivity is related to various geological parameters such as the mineral and fluid content, porosity and degree of water saturation in the rock.

Substrates used in perovskite solar cells as front contact are usually transparent conductive oxide (TCO) to allow light to pass through the device. The dominating TCO employed in perovskite solar cells are indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO). However, it is imperative to investigate alternative TCOs due to the scarcity of indium metal, relatively low electrical conductivity and high leakage current in ITO and FTO. In this study, simulation has been carried out using Solar Capacitance Simulator (SCAPS) to investigate the efficiency of methyl-ammonium tin iodide (CH3NH3SnI3) based solar cells including various TCOs such as boron-doped zinc oxide (BZO), molybdenum trioxide (MoO3) and zinc oxide (ZnO). TCO parameters such as thickness, donor concentration and operating temperature were varied to study their influence on device performance. The best device performance was achieved using MoO3 with power conversion efficiency of 25.83 % and Jsc, Voc and FF of 32.44 mA/cm2, 0.979 V and 81.38 % respectively. The work shows the potential of fabricating an improved CH3NH3SnI3 perovskite solar cell with MoO3 as front contact.

The paper sets out to determine the adequacy or otherwise of the definition of Public Private Partnership (PPP) in Nigeria. As a result of paucity of public funds, Nigeria introduced the concept of PPP in its public procurement strategy so as to tackle its glaring infrastructure deficit, which presently, is put at 70% -75% of GDP. Despite the enthusiasm of stakeholders in this respect, the fundamental challenge is the capacity, within the extant legal framework that used the term 'concession', to identify the scope, parameters and limitations of the concept in exploring available options for successful delivery of PPP projects in Nigeria. The significance of correct identification of PPP parameters for the participation of the private sector in the delivery of public infrastructure and services cannot therefore be underestimated considering Nigeria's aspiration and the role of infrastructure to economic growth and national prosperity. Using a doctrinal research methodology and a purposive sampling technique, the paper reviewed extant definitions of the concept in many PPP national jurisdictions, international organizations and relevant academic writers to conclude that the definition of PPP under section 36 of the Infrastructure Concession Regulatory Commission (ICRC) Act is inadequate. Such a definition is incapable of capacitating public authorities to explore all available PPP options in their effort to achieve Nigeria's desire for private financing of public infrastructure and services. Out of the five legal parameters identified by this paper for any standard definition of PPP, the definition under section 36 of the ICRC Act met only two parameters. It therefore recommended that the ICRC Act should be amended to be more expansive as to accommodate the different types, classifications and parameters of the PPP definitions propounded in the guidelines of many Multilateral and Development Banks (MDBs).