Showing items 1 - 20 of 6463

Your selections:

Biomimetic strategies for climate change mitigation in the built environment

- Aanuoluwapo, Oguntona Olusegun, Aigbavboa, Clinton Ohis

  • Authors: Aanuoluwapo, Oguntona Olusegun , Aigbavboa, Clinton Ohis
  • Date: 2017
  • Subjects: Biomimicry , Built environment , Climate change
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/247631 , uj:25716 , Citation: Aanuoluwapo, O.O. & Aigbavboa, C.O. 2017. Biomimetic strategies for climate change mitigation in the built environment.
  • Description: Abstract: Out of the numerous challenges facing mankind globally, the impact of climate change poses more threat. These impacts include sea-level rise, more frequent floods from heavy rainfall and notably among others, intense droughts. Despite the United Nations anchored events and conferences geared towards tackling climate change, little success has been recorded till date. Biomimicry, a novel science and method that studies nature’s models and then emulates their forms, processes, and strategies offer a sustainable approach to this menace of climate change. It also has the potential to offer efficient alternatives to the human activities that contribute to the depletion and pollution of the environment. Hence, the objective of this paper is to evaluate and present the potential of biomimicry in for climate change mitigation in the built environment. An extant literature review was conducted on biomimicry and its roles in tackling climate change through mitigation and adaptation. The result explores various Biomimetic innovations and applications with their potential to sustainably mitigate the menace of climate change if adopted. This study is expected to refocus human efforts towards biomimicry where it is believed that nature, during its 3.8 billion years of existence has evolved with highly efficient processes and systems, with the potential to produce solutions to the environmental challenges facing mankind, especially climate change.
  • Full Text:

Herding behaviour in financial markets : empirical evidence from the Johannesburg Stock Exchange

- Ababio, Kofi A., Muteba Mwamba, John W.

Empirical examination of herding behaviour in the Johannesburg stock exchange : a sectoral analysis

- Ababio, Kofi A., Mwamba, John M.

Test of herding behaviour in the Johannesburg stock exchange : application of quantile regression model

- Ababio, Kofi Agyarko, Mwamba, John Muteba

Optimisation of mixed assets portfolio using copula differential evolution : a behavioural approach

- Ababio, Kofi Agyarko, Mba, Jules Clement, Koumba, Ur

A deep gold mine metagenome as a source of novel esterases.

- Abbai, Nathlee S., Van Heerden, Esta, Piater, Lizelle A., Litthauer, Derek

  • Authors: Abbai, Nathlee S. , Van Heerden, Esta , Piater, Lizelle A. , Litthauer, Derek
  • Date: 2011
  • Subjects: Lipolytic activity , Biofilms , Esterases
  • Type: Article
  • Identifier: uj:5843 , ISSN 1684–5315 , http://hdl.handle.net/10210/7898
  • Description: New sources of enzymes for biotechnological applications are continually being sought for. While diverse microbial ecosysyems have been demonstrated in the deep subsurfaces, deep mines provide easy access to these specialist communities. Therefore, the aim of this study was to assess a deep mine biofilm as a source of novel esterase enzymes. Biofilm was collected from the Beatrix Mine in South Africa, at a depth of 808 m. Assessment of the diversity revealed a group of previously uncultured bacteria and archaea. A metagenome library was screened for esterolytic activity, producing two esterolytic clones: a phospholipase patatin protein and an isochorismatase family protein. The isochorismatase family protein contained the catalytic Asp and Cys but not the Arg, which is considered as important for catalysis. The patatin showed 55% similarity to its closest relative; the patatin family protein from Plesiocystis pacifica. The expressed patatin displayed a preference for the C6 ester and was maximally active at pH 8 and 30°C. This study reported that screening of a relatively small metagenome library from the deep mine biofilm provided two esterolytic clones, which differed from their known counterparts. This indicates that the deep mine ecosystems contain an untapped resource of novel and potentially useful enzymes which may have applications in chemical syntheses.
  • Full Text:

Predictive mathematical modeling and computer simulation of direct ethanol fuel cell

- Abdulkareem, A. S., Jimoh, A., Afolabi, A. S., Muzenda, E., Okeke, A. C.

  • Authors: Abdulkareem, A. S. , Jimoh, A. , Afolabi, A. S. , Muzenda, E. , Okeke, A. C.
  • Date: 2016
  • Subjects: Fuel cell , Direct ethanol fuel cell , Predictive mathematical modeling
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/213692 , uj:21184 , Citation: Abdulkareem, A.S. et al. 2016. Predictive mathematical modeling and computer simulation of direct ethanol fuel cell.
  • Description: Abstract: The challenges of finding a better substitute of energy as well as the short comings identify with direct ethanol fuel cell, this includes; high anode over potential and crossover necessitate the need to investigate the influence operating parameters on the performance of fuel through computer simulation. This study focus on the development of a predictive mathematical modeling for direct ethanol fuel cell for the purpose of investigating the influence pressure, temperature cathode and reactants concentration on the performance, efficiency and heat generated by the cell. Results obtained indicate that increase in operating temperature resulted led to decrement in output voltage and cell efficiency, while same condition of increasing the temperature positively favour the heat generated from the cell. Simulated results also show that cell performance is improved with increase in concentration of the fuel (ethanol) and oxidant (oxygen). It can be inferred from this study that the cell performance of DEFC can be theoretically predicted with the developed model.
  • Full Text:

The need to incorporate senior caregivers in health education relating to malaria in rural areas

- Abdullahi, Ali Arazeem, Senekal, Anton, Van Zyl-Schalekamp, Cecilia

  • Authors: Abdullahi, Ali Arazeem , Senekal, Anton , Van Zyl-Schalekamp, Cecilia
  • Date: 2012
  • Subjects: Caregivers - Nigeria , Malaria -Treatment - Nigeria , Child health services - Nigeria
  • Type: Article
  • Identifier: uj:5986 , http://www.bangladeshsociology.org , http://hdl.handle.net/10210/8615
  • Description: Using a combination of qualitative research techniques this study has investigated the place and the roles of senior caregivers in the management of malaria in children in rural communities of Nigeria. The study was conducted in Okanle and Fajeromi in Ifelodun Local Government Area of Kwara State. The study shows that a variation may exist between young and older caregivers with respect to desire for modern or traditional medicines in the treatment of malaria. While most senior caregivers continued to rely on herbal treatment regimens, younger parents seemed to have preference for modern treatment but not without difficulties. Given their important position within the extended family structure, senior caregivers seemed to also possess tremendous influence on health care decision making process. The study suggests the need to incorporate senior caregivers in health promotion strategy related to malaria control in rural communities.
  • Full Text:

Equilibria and isosteric heat of adsorption of methane on activated carbons derived from South African coal discards

- Abdulsalam, Jibril, Mulopo, Jean, Bada, Samson Oluwaseyi, Oboirien, Bilainu

  • Authors: Abdulsalam, Jibril , Mulopo, Jean , Bada, Samson Oluwaseyi , Oboirien, Bilainu
  • Date: 2020
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/461783 , uj:41143 , Citation: Abdulsalam J, Mulopo J, Bada SO, Oboirien B. Equilibria and Isosteric Heat of Adsorption of Methane on Activated Carbons Derived from South African Coal Discards. ACS Omega. 2020 Dec;5(50):32530-32539. DOI: 10.1021/acsomega.0c04744.
  • Description: Abstract: Isosteric heat of adsorption (Hst) is critical for evaluating the thermal effects of adsorption-based storage systems. Poor management of the thermal effects of an adsorptive storage system often alters the overall performance of the storage system. In this study, methane equilibrium uptake on activated carbons derived from coal discards and isosteric heat of adsorption were evaluated. The methane adsorption capacity of the produced activated carbons was measured using a high-pressure volumetric analyzer. The isotherm results in temperature ranges of 0−50 °C and pressure of up to 40 bar are analyzed using the Langmuir, Tóth, and Dubinin−Astakhov (DA) isotherm models. The results showed that, for the two activated carbons, the DA model was the best fit. In addition, we evaluated the isosteric heat of adsorption using two theoretical frameworks, Maxwell’s thermodynamic relations and the modified Polanyi potential function. The Tóth potential function and Clausius−Clapeyron equations were applied to the Dubinin−Astakhov adsorption model to obtain an analytical expression of Hst. Both methods were compared, and the result showed an overall error margin between 6 and 12%. The values of Hst obtained are over a range of 10−17 kJ/mol. It was observed that Hst decreases with an increase in methane fractional load. The Hst values obtained are useful in designing an efficient thermodynamic scheme for the ANG storage system.
  • Full Text:

Microstructural characterization of friction stir lap welds of aluminium incorporated with titanium carbide

- Abegunde, O. O., Akinlabi, Esther Titilayo, Madyira, D. M.

  • Authors: Abegunde, O. O. , Akinlabi, Esther Titilayo , Madyira, D. M.
  • Date: 2015-07-01
  • Subjects: Aluminium , Friction stir welding , Titanium carbide , Aluminum
  • Type: Article
  • Identifier: uj:5123 , ISBN 9789881404701 , http://hdl.handle.net/10210/14085
  • Description: In this research study, the characterization of the microstructure evolution of friction stir lap welds (FSLW) of Aluminium incorporated with Titanium Carbide powder to form Aluminium based composites is presented. The Titanium Carbide powder was infused at the weld interface to produce a composite. The FSLW were conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS). Different welding parameters were used for the welding process. Rotational speeds of 1600 rpm and 2000 rpm and transverse speeds of 100 mm/min, 200 mm/min and 300 mm/min were employed. The process parameters were carefully selected to represent a low, medium and high setting for the feed rates. The microstructural evolution of the samples were studied. Optical microscope and scanning electron microscopy (SEM) techniques were used to investigate the particle distribution of the welded samples. The results obtained revealed the influence of the welding parameters on the particle distribution of the welded samples. A homogenous mixture of the materials was observed at higher rotational speed of 2000 rpm.
  • Full Text:

Microstructural evolution and mechanical characterizations of AL-TiC matrix composites produced via friction stir

- Abegunde, Olayinka O., Akinlabi, Esther Titilayo, Madyira, Daniel M.

  • Authors: Abegunde, Olayinka O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
  • Date: 2017
  • Subjects: Friction stir welding , Metal matrix composite , Aluminium
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/236151 , uj:24161 , Citation: Abegunde, O.O., Akinlabi, E.T. & Madyira, D.M. 2017. Microstructural evolution and mechanical characterizations of AL-TiC matrix composites produced via friction stir.
  • Description: Abstract: In this research work, ample study was conducted on the material characterization of aluminium (Al) and titanium carbide (TiC) metal matrix composites produced via friction stir welding. Different process parameters were employed for the welding process. Rotational speeds of 1600 rpm to 2000 rpm at an interval of 200 rpm and traverse speeds of 100 to 300 mm/min at an interval of 100 mm/min were employed for the welding conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS) platform. The characterizations carried out include optical microscopy and the scanning electron microscopy analyses combined with Energy Dispersive Spectroscopy (SEM/EDS) techniques to investigate the particle distribution, microstructural evolution and the chemical analysis of the welded samples. Vickers microhardness tests were used to determine the hardness distribution of the welded zone and tensile testing was conducted to quantify the strength of the welded area to the base metal in order to establish the optimal process parameters. Based on the results obtained from the characterization analysis, it was found that the process parameters played a major role in the microstructural evolution. Homogenous distribution of the TiC particles was observed at high rotational speed of 2000 rpm and low traverse speed of 100 mm/min. The highest hardness value was measured at the stir zone of the weld due to the presence of the TiC reinforcement particles. The tensile strength also increased as the rotational speed increased and 92% joint efficiency was recorded in a sample produced at 2000 rpm and 100 mm/min. The EDS analysis revealed that Al, Ti and C made up the composition formed at the stir zone. The optimum process parameter setting was found to be at 2000 rpm and 100 mm/min and can be recommended.
  • Full Text:

Comparative study of 3G and 4GLTE network

- Abioye, A. D., Joseph, M. K., Ferreira, Hendrik C.

  • Authors: Abioye, A. D. , Joseph, M. K. , Ferreira, Hendrik C.
  • Date: 2015-09
  • Subjects: Mobile communication networks , Wireless networks , 3G networks , 4GLTE networks
  • Type: Article
  • Identifier: uj:5231 , ISSN 17938244 , http://hdl.handle.net/10210/14575
  • Description: The area of mobile communication is fast developing as a result of the technological advancement in the field of mobile and wireless communication. Obviously, 3G was once acclaimed as a recent technology in the field of wireless and mobile communication until the arrival of 4GLTE. The quest for a faster speed, lower latency, better QoS and ability to interoperate with all existing network are some of the factors that brought up the emergence of 4GLTE network. In this paper we provide an overview of all network generations from the first generation to the fourth generation as well as the differentiating features that supports the superiority of the 4GLTE network to the 3G network are well stated. We use self-analytical tools like bar charts to compare the features of 4GLTE and 3G networks. The concluding part of this paper presents improvements needed in 4GLTE.
  • Full Text:

Design of energy efficient hybrid VLC/RF/PLC communication system for indoor networks

- Aboagye, Sylvester, Ibrahim, Ahmed, Ngatched, Telex M. N., Ndjiongue, Alain R., Dobre, Octavia A.

  • Authors: Aboagye, Sylvester , Ibrahim, Ahmed , Ngatched, Telex M. N. , Ndjiongue, Alain R. , Dobre, Octavia A.
  • Date: 2019
  • Subjects: Energy efficiency , Visible light communication , Power line communication
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/399299 , uj:33275 , Citation: Aboagye, S. et al. 2019. Design of energy efficient hybrid VLC/RF/PLC communication system for indoor networks.
  • Description: Abstract: Integrating visible light communication (VLC) system with indoor radio frequency (RF) network is seen as a possible way of increasing the capacity and coverage of indoor networks. In such a hybrid network, the traffic generated at the indoor RF and VLC access points must be backhauled to the core network. Power line communication (PLC) technology is seen as a cost-effective backhaul (BH) solution due to its infrastructure availability in every home. In this letter, a novel system model that captures the joint effect of power and BH flow optimization for hybrid VLC/RF/PLC indoor communication network is proposed. For the proposed system model, the problem of energy efficiency (EE) maximization via power and BH flow optimization is formulated as a non-convex problem, and then transformed into a convex problem via the Dinkelbach’s approach. An energy efficient algorithm is proposed to solve this joint problem to optimality. Simulation results are used to verify the superiority of the proposed hybrid VLC/RF/PLC system and algorithm over a conventional indoor RF system and equal power allocation benchmark scheme, respectively, in terms of network throughput, power consumption, and EE.
  • Full Text:

A longitudinal assessment of Nigeria’s research output for evidence based science policy development

- Abodunde, Olufikayo, Jegede, Oluseye O., Oyebisi, Timothy

R&D productivity for science, technology and innovation policy development in Nigeria : a scientometric analysis of academic literature

- Abodunde, Olufikayo O., Jegede, Oluseye O.

  • Authors: Abodunde, Olufikayo O. , Jegede, Oluseye O.
  • Date: 2020
  • Subjects: STI Policy , Research outputs , Researchers
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/457986 , uj:40663 , Citation: Abodunde, O.O. & Jegede, O.O. 2020. R&D productivity for science, technology and innovation policy development in Nigeria : a scientometric analysis of academic literature.
  • Description: Abstract: The study purposively selected the 148 Science and Engineering Journals out of the 221 Journals registered on the African Journal Online (AJOL) directory. Data harvested was analyzed on a year-wise basis from 2012 to 2016, to identify the positive or negative growth trend of research outputs. The open source software “Publish or Perish” was used to query metrical data for the purposively selected journals by accessing the Google scholar database over the internet. Data was obtained to determine the degree of Collaboration based on the 19 thematic areas as identified in the Nigerian science, technology and innovation (STI) Policy document. It was further examined by measuring the Authorship Pattern and Co-Authorship Index (CAI). The analysis from the study provided information on the productivity of research that has been carried out in the various thematic areas in the Nigerian Science Technology and Innovation (STI) Policy. It also provided information on the nature and extent of collaboration for research among the actors of the research and development system. It thus also served as a reference tool for policymakers to reviewing science, technology and innovation policy in Nigeria.
  • Full Text:

A holistic assessment of construction and demolition waste management in the Nigerian construction projects

- Aboginije, Ademilade, Aigbavboa, Clinton, Thwala, Wellington

The use of laser irradiation to stimulate adipose derived stem cell proliferation and differentiation for use in autologous grafts

- Abrahamse, H.

  • Authors: Abrahamse, H.
  • Date: 2009
  • Subjects: Autologous grafts , Laser irradiation , Adipose derived stem cell proliferation , Adipose derived stem cell differentiation , Smooth muscle cell
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/375285 , uj:6216 , ISBN 978-0-7354-0711-4 , http://hdl.handle.net/10210/5306
  • Description: Stem cells are characterized by the qualities of self-renewal, long term viability, and the ability to differentiate into various cell types. Historically, stem cells have been isolated from the inner cell mass of biastocysts and harvesting these cells resulted in the death of the embryo leading to religious, political and ethical issues. The identification and subsequent isolation of adult stem cells from bone marrow stroma have been welcomed as an alternate source for stem cells. The clinical use of Mesenchymal Stem Cells (MSCs) presented problems such as limited cell number, pain and morbidity upon isolation. Adipose tissue is derived from the mesenchyme, is easily isolated, a reliable source of stem cells and able to differentiate into different cell types including smooth muscle. Over the past few years, the identification and characterization of stem cells has led the potential use of these cells as a promising alternative to cell replacement therapy. Smooth muscle is a major component of human tissues and is essential for the normal functioning of many different organs. Low intensity laser irradiation has been shown to increase viability, protein expression and migration of stem cells in Vitro, and to stimulate proliferation of various types of stem cells. In addition, the use of laser irradiation to stimulate differentiation in the absence of growth factors has also been demonstrated in normal human neural progenitor cells (NHNPCs) in vitro where NHNPCs are not only capable of being sustained by light in the absence of growth factors, but that they are also able to differentiate normally as assessed by neurite formation. Our work has focused on the ability of laser irradiation to proliferate adipose derived stem cells (ADSCs), maintain ADSC character and increase the rate and maintenance of differentiation of ADSCs into smooth muscle and skin fibroblast cells. Current studies are also investigating the effect of different irradiation wavelengths and fluences on ADSC viability and proliferation. This paper reviews the development of MSCs as potential therapeutic interventions such as autologous grafts as well as the contribution 0 f low intensity laser irradiation on the maintenance of these cells.
  • Full Text:

Genetic aberrations associated with photodynamic therapy in colorectal cancer cells

- Abrahamse, Heidi, Houreld, Nicolette Nadene

  • Authors: Abrahamse, Heidi , Houreld, Nicolette Nadene
  • Date: 2019
  • Subjects: Photodynamic therapy, Colorectal cancer, Zinc phthalocyanine;
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/396389 , uj:32909 , Citation : Abrahamse, H. 2019. Genetic aberrations associated with photodynamic therapy in colorectal cancer cells @ Houreld, N.N. , http://dx.doi.org/10.3390/ijms20133254
  • Description: Abstract : Photodynamic therapy (PDT) is a cancer treatment modality that utilizes three components: light (λ 650–750 nm), a photosensitizer (PS) and molecular oxygen, which upon activation renders the modality effective. Colorectal cancer has one of the highest incident rates as well as a high mortality rate worldwide. In this study, a zinc (Zn) metal-based phthalocyanine (ZnPcSmix) PS was used to determine its efficacy for the treatment of colon adenocarcinoma cells (DLD-1 and Caco-2). Photoactivation of the PS was achieved by laser irradiation at a wavelength of 680 nm. Dose responses were performed to establish optimal PS concentration and irradiation fluence. A working combination of 20 µM ZnPcSmix and 5 J/cm2 was used. Biochemical responses were determined after 1 or 24 h incubation post-treatment. Since ZnPcSmix is localized in lysosomes and mitochondria, mitochondrial destabilization analysis was performed monitoring mitochondrial membrane potential (MMP). Cytosolic acidification was determined measuring hydrogen peroxide (H2O2) levels in the cytoplasm. Having established apoptotic cell death induction, an apoptosis PCR array was performed to establish the apoptotic mechanism. In DLD-1 cells, expression of genes included 3 up-regulated and 20 down-regulated genes while in Caco-2 cells, there were 16 up-regulated and 22 down-regulated genes. In both cell lines, in up-regulated genes, there was a combination of pro- and anti-apoptotic genes that were significantly expressed. Gene expression results showed that more tumorigenic cells (DLD-1) went through apoptosis; however, they exhibit increased risk of resistance and recurrence, while less tumorigenic Caco-2 cells responded better to PDT, thus being suggestive of a better prognosis post-PDT treatment. In addition, the possible apoptotic mechanisms of cell death were deduced based on the genetic expression profiling of regulatory apoptotic inducing factors.
  • Full Text:

New photosensitizers for photodynamic therapy

- Abrahamse, Heidi, Hamblin, Michael R.

  • Authors: Abrahamse, Heidi , Hamblin, Michael R.
  • Date: 2016
  • Subjects: Naturally occurring photosensitizers , Photochemical mechanisms , Photodynamic therapy
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/215235 , uj:21381 , Citation: Abrahamse, H & Hamblin, M.R. 2016. New photosensitizers for photodynamic therapy.
  • Description: Abstract: Photodynamic therapy (PDT) was discovered more than 100 years ago, and has since become a well-studied therapy for cancer and various non-malignant diseases including infections. PDT uses photosensitizers (PSs, non-toxic dyes) that are activated by absorption of visible light to initially form the excited singlet state, followed by transition to the long-lived excited triplet state. This triplet state can undergo photochemical reactions in the presence of oxygen to form reactive oxygen species (including singlet oxygen) that can destroy cancer cells, pathogenic microbes and unwanted tissue. The dual-specificity of PDT relies on accumulation of the PS in diseased tissue and also on localized light delivery. Tetrapyrrole structures such as porphyrins, chlorins, bacteriochlorins and phthalocyanines with appropriate functionalization have been widely investigated in PDT, and several compounds have received clinical approval. Other molecular structures including the synthetic dyes classes as phenothiazinium, squaraine and BODIPY (boron-dipyrromethene), transition metal complexes, and natural products such as hypericin, riboflavin and curcumin have been investigated. Targeted PDT uses PSs conjugated to antibodies, peptides, proteins and other ligands with specific cellular receptors. Nanotechnology has made a significant contribution to PDT, giving rise to approaches such as nanoparticle delivery, fullerene-based PSs, titania photocatalysis, and the use of upconverting nanoparticles to increase light penetration into tissue. Future directions include photochemical internalization, genetically encoded protein PSs, theranostics, two-photon absorption PDT, and sonodynamic therapy using ultrasound.
  • Full Text: false

Photobiomodulation : an accepted therapeutic modality?

- Abrahamse, Heidi

  • Disclaimer
  • Privacy
  • Copyright
  • Contact