Choosing a Better Delay Line Medium between Single-Mode and Multi-Mode Optical Fibers: the Effect of Bending

Optical fiber cables are materials whose core is made of silica and other materials such as chalcogenide glasses; they transmit a digital signal via light pulses through an extremely thin strand of glass. The light propagates and is being guided by the core which is surrounded by the cladding. Light travels in the optical fiber in the form of total internal reflection in the core of the fibers. The flexibility, low tensile strength, low signal loss, high bandwidth and other characteristics of optical fibers favors it for use as a delay medium in many applications. Another favorable characteristic of optical fiber delay lines is are their relative insensitivities to environmental effects and electromagnetic interferences. The immunity of optical fibers to interferences and their less weight added advantages to it for use as delay medium. Single-mode and multi-mode are the two most popular types of optical fibers. Single-mode fibers have good propagation and delay properties with a minimal loss that allows the signal to propagate in a large distance with insignificant distortion or attenuation. The percentage of power transmission of single-mode fibers is found to be higher than that of the multi-mode fibers. It is, therefore, a preferred type for use as a delay line. In this paper, relative studies of the two optical fibers modes, and the results of power input/output measurement of the two modes are presented with a view to coming up with a better type for use as a delay medium

Model evaluation of proton exchange membrane fuel cell performance utilizing platinum catalyst

Designing a more efficient and cost effective proton exchange membrane fuel cell (PEMFC) is highly required. This is due to its enormous potentials in portable and transportation applications. The main component that needs to be optimally design to achieve this purpose is the catalyst layer (CL) of the fuel cell. Recent studies have focused in effective utilization of the precious metal, usually platinum (Pt) which is used as the most effective catalyst so far. Two ways are employed to achieve this. Firstly, is by reducing the Pt mass loading and secondly is reducing the Pt to smaller nanoparticles to get more access surface area for the reacting fuel while at the same time reducing the overall cost of the system. Despite several experimental, complex model and simulation studies, simple ways of studying more effective utilization of the Pt catalyst are still inadquate. As a result, a simple model is developed by combining the effects of Pt catalyst particle size, Pt mass loading and Pt/C ratio in order to determine their influence on PEMFC performance. This was done by modeling the CL in the low current density of the fuel cell polarization curve only using the well known Butler-Volmer kinetics. The influence of nanoparticles of diameters between 1.5 nm to 6.5 nm, Pt mass loadings (0.4 mgPt/cm2, 0.35 mgPt/cm2, 0.05 mgPt/cm2 and 0.03 mgPt/cm2) and Pt/C ratio are examined. It is observed that the reduction in particle size increased the PEMFC performance. Furthermore, reduction of Pt mass loading increased the performance to certain limit of around 0.03 mgPt/cm2 loading. Supporting the Pt on carbon helped to reduce the amount of Pt used while improving fuel cell performance. The results are compared with other experiment and model findings. An important feature of this simple model suggests that it can be used to evaluate PEMFC performance without performing highly complex model calculations

Model evaluation of proton exchange membrance fuel cell performance utilizing platinum catalyst

Designing a more efficient and cost effective proton exchange membrane fuel cell (PEMFC) is highly required. This is due to its enormous potentials in portable and transportation applications. The main component that needs to be optimally design to achieve this purpose is the catalyst layer (CL) of the fuel cell. Recent studies have focused in effective utilization of the precious metal, usually platinum (Pt) which is used as the most effective catalyst so far. Two ways are employed to achieve this. Firstly, is by reducing the Pt mass loading and secondly is reducing the Pt to smaller nanoparticles to get more access surface area for the reacting fuel while at the same time reducing the overall cost of the system. Despite several experimental, complex model and simulation studies, simple ways of studying more effective utilization of the Pt catalyst are still inadquate. As a result, a simple model is developed by combining the effects of Pt catalyst particle size, Pt mass loading and Pt/C ratio in order to determine their influence on PEMFC performance. This was done by modeling the CL in the low current density of the fuel cell polarization curve only using the well known Butler-Volmer kinetics. The influence of nanoparticles of diameters between 1.5 nm to 6.5 nm, Pt mass loadings (0.4 mgPt/cm2, 0.35 mgPt/cm2, 0.05 mgPt/cm2 and 0.03 mgPt/cm2) and Pt/C ratio are examined. It is observed that the reduction in particle size increased the PEMFC performance. Furthermore, reduction of Pt mass loading increased the performance to certain limit of around 0.03 mgPt/cm2 loading. Supporting the Pt on carbon helped to reduce the amount of Pt used while improving fuel cell performance. The results are compared with other experiment and model findings. An important feature of this simple model suggests that it can be used to evaluate PEMFC performance without performing highly complex model calculations

Antioxidant and Antimicrobial Activities of Green Synthesized Silver Nanoparticle Using Moringa Oleifera Seeds Extracts

Nanotechnology deals with materials in nanoscale that exhibit incredible chemical, physical and biological properties. This study is aimed at synthesizing silver nanoparticles from Moringa oleifera seed using aqueous and ethanol as solvents and compare their antioxidant as well as antimicrobial activities of these two synthesized nanoparticles. The synthesized nanoparticles were subjected to preliminary characterization using UV- spectroscopy to ensure their formation which were confirmed by attaining the plasmon resonance surface of both particles at 320nm. Standard assay for antioxidant scavenging of ferric ion and DDPH were employed and standard methods for drop plate technique, minimum inhibition concentration and minimum bactericidal/fungicidal concentrations were used. The results indicate that silver nanoparticles synthesized from ethanol extract (EEMS) has excellent ferric ion scavenging activity compared to silver nanoparticles synthesized from aqueous extract (AEMS), while AEMS has 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging potential compared to EEMS. Both nanoparticles show the antimicrobial efficiency were dose dependent but more inhibition zone was observed on EEMS using drop plate technique at 25mg/dl against all the organisms used (S. aureus, E. coli and C. albican). And in minimum inhibition concentrations, the result shows both particles inhibit the growth of all organisms at 6.25 µg/dl except against E. coli which is at 12.5 µg/ml by EEMS. Similarly, minimum bactericidal / fungicidal concentrations were the same in all organisms at 12.5 µg/ml except against C. albican which was at 6.25 µg/ml by EEMS. The finding revealed that both EEMS and AEMS are good antioxidants and antimicrobial agents and their activities are concentration dependent

Web-Based Collaborative Learning: A proposed Learning Platform for the School of ICT, Auchi Polytechnic

Technological advancements in the World Wide Web continue to gain widespread adoption, with various kinds of applications finding their use  in education, including those for 'digital collaboration'. The term has become widely known for its extension of our traditional means of distributed learning and workflow. In present-day Nigeria, collaboration between students and educators in most tertiary institutions still involves the most basic use of instant messaging tools provided via online chat forums, google groups, WhatsApp, for knowledge sharing over the internet. However, these tools come with their limitations. Take 'Yahoo' and 'google' groups for example; yahoo groups are meant solely for students possessing yahoo mail accounts, and the same applies for google groups. Overall, the user-access convention on these platforms makes it difficult for students to enjoy any cross-platform privileges in the absence of email ownership on the particular service domain. Owing to this, our research project sought to bridge this identified gap, with a pilot project in the School of ICT, Federal Polytechnic, Auchi. We proposed the development and implementation of this unified platform to meet the salient and underlying collaborative need within our learning community. The system (PolyCollab) is a cross-platform web application, hosted on an online server and designed using MVC model architecture. The framework was developed using PHP, CSS3, HTML5, and MySQL for the database. The system was subjected to evaluation by potential users within the institution, and on the whole met with predefined user-specific requirements. Keywords: Web-Based Learning, Collaborative Learning, Distributed Learning Environment DOI: 10.7176/CEIS/12-2-05 Publication date: April 30th 202

The Mediating Effect of Work Engagement in the Link between Affective Commitment and Employee Competence in Nigeria Universal Basic Education system

Competency is seen as the fundamental feature of individuals which described their job skill, attitude and knowledge. The main aim of this paper is to explore the mediating effect of work engagement (WE) in the link between affective commitment and employee competence (EC) in Nigerian Universal Basic Education system Administration (UBESA). In spite of the importance of affective commitment as an essential practice impelling EC in organisations, prior studies mainly consider other internal factors such as leadership, management practices, and job satisfaction among others. Studies that attempt to examine the influence of affective commitment on EC as well as the mechanism through which it influences EC seem to be scarce in the literature. The current study used WE as a mediating variable in explaining the relationship between affective commitment and EC as well as establishing the link between the given variables. The paper employed the Ability Motivation Opportunity (AMO) theory and Social Exchange theory (SET) in emphasizing the impact of practices that are capable of enhancing EC, as well as understanding employee’s behaviour and their relationship with their organisation in the quest for achieving success. A quantitative survey method was used, while data were collected within six states UBESA (Jigawa, Kano, Kaduna, Katsina, Sokoto and Zamfara states) in North Western region of Nigeria. Data was analysed with a total number of 387 questionnaires using SPSS-AMOS software-24. The findings indicated that WE mediate the relationship between affective commitment and EC. In conclusion, the study made some vital suggestions for future studies.  

A model study of surface state on optical bandgap of silicon nanowires

A theoretical approach is carried out to study the role of surface state in silicon nanowires. The influences of size and surface passivation on the bandgap energy and photoluminescence spectra of silicon nanowires with diameter between 4 to 12nm are examined. It is observed that visible PL in silicon nanowires is due to quantum confinement and surface passivation. But the energy recombination of electron and holes in the quantum confined nanostructures is responsible for the visible PL. In this work, models from quantum bandgap and photoluminescence intensity are adopted to explain the size dependent surface luminescence. Investigation show that the nanowires of smaller size with surface impurities revealed higher bandgap energy. Oxygenated surface is found to have higher energy than hydrogenated surface. The features of PL spectra of Si nanowires suggest that these models are significant for understanding the mechanism of visible PL from SINWs.Keywords: Photoluminescence, Surface State, Band gap, Quantum Confinemen

Structural and luminescence characterization of lithium-borosulfophosphate glasses containing dysprosium ions

Rare earth doped glasses have been a great deal of research interest due to their prominent applications in laser lighting technology. However, achieving highly efficient yellow light emission from these materials require the collective efforts of many researchers across the world. Hence, a series of high optical quality dysprosium doped lithium-borosulfophosphate glasses with chemical composition of 15Li2O-30B2O3-15SO3-(40-x)P2O5-xDy2O3 (where x = 0.1, 0.3, 0.5, 0.7 and 1.0 in mol%) were prepared by convectional melt quenching technique and characterized by X-Ray diffraction (XRD), Fourier Transform Infrared (FTIR) and Photoluminescence (PL) measurements. XRD pattern of the host glass confirms its amorphous nature while the results from FTIR spectra analysis indicates the presence of BO3, BO4, PO4 and SO42- groups in the host network structure. The photoluminescence spectral analysis revealed three emission bands at 494 nm, 585 nm and 673 nm attributed to the electronic transitions of 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H15/2,respectively, under the excitation of 386 nm. Among all the prepared glass samples, 1.0 mol% Dy3+ contained glass sample exhibits an intense yellow emission at 585 nm which specifies its prospective suitability for yellow laser applications.Keywords: Borosulfophosphate glasses, Dysprosium ions, Fourier transform infrared spectroscopy, Photoluminescence analysi

Digital Entrepreneurship in the Last Decade: A Systematic Review

The objective of this paper is to investigate the effects ICT has on the sustainability of Digital Entrepreneurship in Nigeria.  Furthermore, this paper seeks to determine if the utilization of ICT can forecast the rate of start-ups in the Digital Entrepreneurship sector and interrogate the characteristics and inter-relationships inherent in Digital Entrepreneurship.   To achieve this objective, a systematic literature review using the Systematic Quantitative Assessment Technique (SQAT) was the methodology used to review 45 DE articles published over the last decade (2012 – 2021).   To provide a thorough, impartial amalgam of the reviewed articles, this paper analysed the time distribution, geographic distribution, types and data collection methods of the 45 DE articles.  The review revealed that existing research has been both empirical and conceptual in equal measure with only one instance in mixed mode.  The parity suggests that future researchers should endeavour to conduct more conceptual research to underpin the envisaged accelerated growth of DE