Showing papers by "Adama University published in 2016"

Application of biosurfactants in environmental biotechnology; remediation of oil and heavy metal

Abstract: Many toxic substances have been introduced into environment through human activities. These compounds are danger to human health when they are ultimately or immediately in contact with soil particles. A conventional method to reduce, degrade and remove these substances is associated with some risk. In recent years, microorganisms have proved a unique role in the degradation and detoxification of polluted soil and water environments and, this process has been termed bio reclamation. The diversity of bioemulsifiers/biosurfactants makes them an attractive group and important key roles in various fields of industrial as well as biotechnological applications such as enhanced oil recovery, biodegradation of pollutants, and pharmaceutics. Environmental application of microbial surfactant has been shown as a promising due to solubilization of low solubility compounds, low toxicity observed and efficacy in improving biodegradation. However, it is important to note that full scale tests and more information is require to predict the behavior and model of surfactant function on the remediation process with biosurfactants. The purpose of this review is to describe the state of art in the potential applications of biosurfactants in remediation of environmental pollution caused by oil and heavy metal.

Behavior of Expansive Soil Treated with Steel Slag, Rice Husk Ash, and Lime

Abstract: This paper presents the stabilization of expansive soil (C) with steel slag (SS), rice husk ash (RHA), and quick lime (L). The geotechnical properties, shearing strength characteristics, and dynamic properties of stabilized soil have been studied. The optimum mix is found to be in the proportion of 65C+20SS+5L+10RHA. The unconfined compressive test shows that strength of treated soil increases about 45 and 90% for uncured and cured samples at 30 days. The soaked California bearing ratio (CBR) test shows that the strength increases with increasing curing periods from 7 to 30 days. Laboratory strain-controlled cyclic triaxial tests have been carried out under undrained conditions to study the dynamic properties of stabilized soil for different strain amplitudes and frequencies. The stiffness of stabilized soil increases to 58–78% as compared to clay soil. This study discussed the suitability of stabilized material for subgrade pavement.

Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques

Abstract: The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non-fluorescent CF-CFA and CF-CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (KSV), quenching rate constant (kq), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (KSV) between CF and CGA, CFA are 1.84 × 10(4) and 1.04 × 10(4) L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA.

Liver Enzymes Abnormalities among Highly Active Antiretroviral Therapy Experienced and HAART Naïve HIV-1 Infected Patients at Debre Tabor Hospital, North West Ethiopia: A Comparative Cross-Sectional Study

Abstract: Liver disease has emerged as the most common non-AIDS-related cause of death in HIV patients. However, there is limited data regarding this condition including our setting in Ethiopia. Hence, liver enzyme abnormalities among highly active antiretroviral therapy (HAART) experienced and HAART naive patients were assessed in this study. A total of 164 HAART experienced and 164 HAART naive patients were studied. Blood specimen was collected to determine alanine aminotransferase (ALT) and aspartate aminotransferase (AST), CD4 count, and viral hepatitis. The prevalence of liver enzyme abnormality was 20.1% and 22.0% among HAART experienced and HAART naive patients, respectively. The HAART experienced patients had higher mean ALT than HAART naive patients (P = 0.002). Viral hepatitis (AOR = 6.02; 95% CI = 1.87-19.39), opportunistic infections (AOR = 2.91; 95% CI = 1.04-8.19), current CD4 count <200 cells/mm(3) (AOR = 2.16; 95% CI = 1.06-4.39), and male sex (AOR = 1.83; 95% CI = 1.001-3.33) were associated with elevated ALT and/or AST. In conclusion, liver enzyme abnormalities were high in both HAART experienced and HAART naive HIV-1 infected patients. Hence, monitoring and management of liver enzyme abnormalities in HIV-1 infected patients are important in our setting.

Effects of solvent polarity on the absorption and fluorescence spectra of chlorogenic acid and caffeic acid compounds: determination of the dipole moments.

Abstract: The effects of solvent polarity on absorption and fluorescence spectra of biologically active compounds (chlorogenic acid (CGA) and caffeic acids (CA)) have been investigated In both spectra pronounced solvatochromic effects were observed with shift of emission peaks larger than the corresponding UV-vis electronic absorption spectra From solvatochromic theory the ground and excited-state dipole moments were determined experimentally and theoretically The differences between the excited and ground state dipole moment determined by Bakhshiev, Kawski–Chamma–Viallet and Reichardt equations are quite similar The ground and excited-state dipole moments were determined by theoretical quantum chemical calculation using density function theory (DFT) method (Gaussian 09) and were also similar to the experimental results The HOMO-LUMO energy band gaps for CGA and CFA were calculated and found to be 41119 and 18732 eV respectively The results also indicated the CGA molecule is more stable than that of CFA It was also observed that in both compounds the excited state possesses a higher dipole moment than that of the ground state This confirms that the excited state of the hydroxycinnamic compounds is more polarized than that of the ground state and therefore is more sensitive to the solvent Copyright © 2015 John Wiley & Sons, Ltd

Benthic foraminiferal response to relative sea-level changes in the Maastrichtian–Danian succession at the Dakhla Oasis, Western Desert, Egypt

Abstract: The Maastrichtian–Danian benthic foraminiferal diversity and assemblages through sequence stratigraphy were studied at Dakhla Oasis, Egypt. Benthic foraminifera numbers (BFN), high-flux species and characteristic benthic foraminiferal species and genera distribution are also incorporated to assess palaeobathymetry, palaeoenvironment and palaeoproductivity. All these proxies are then taken together to construct a sea-level curve and interpreted in terms of regional tectonics, climate and eustasy. Data suggest a remarkably highly equitable benthic environment deposited in a brackish littoral and/or marsh setting with moderate (?) to low oxygen conditions and reduced salinity (oligotrophic), possibly due to increased precipitation and terrestrial runoff. The interrupted dominance of calcareous forms and high-organic-flux species suggests occasional marine incursions and high palaeoproductivity, due to local upwelling. The inferred sea-level curve replicates the global eustatic curve and suggests that the curve is more influenced by the prevailing climate and global eustasy rather than by regional tectonics. The post-Cretaceous–Palaeogene boundary displays improvement in the environment in terms of diversity and number of species and specimens, with a marked reduction in the abundance of high-organic-flux species during early Paleocene (Danian) time, indicating a shift from a more mesotrophic open marine environment to much reduced oligotrophic conditions.

A flexible lead-free piezoelectric nanogenerator based on vertically aligned BaTiO3 nanotube arrays on a Ti-mesh substrate

Abstract: A uniform piezoelectric film on a flexible substrate is highly desirable for the construction of mechanical energy harvesting devices and self-powered sensors. In this study, we synthesized piezoelectrically active tetragonal phase BaTiO3 (BTO) nanotube arrays uniformly coated on a flexible Ti-mesh substrate by in situ conversion of anodized TiO2 nanotubes using a low temperature hydrothermal process. The direct conversion of the TiO2 nanotube to tetragonal phase BTO provides an excellent way to make flexible composites with a uniform distribution and enhanced volume fraction of piezoelectrically active BTO film. Based on the merits of the tetragonal phase BTO film on a Ti-mesh substrate, a novel fully bendable and mechanically robust piezoelectric nanogenerator (PENG) was fabricated. The oriented tetragonal phase BTO nanotube film on the Ti-mesh substrate was encapsulated in a polydimethylsiloxane (PDMS) elastomeric layer and assembled between two indium tin oxide (ITO) coated polyethylene terephthalate (PET) electrodes to form a flexible PENG. The PENG device can harvest mechanical energy from repeated bending and releasing motions. The resulting output voltage and current reached up to 10.6 V and 1.1 μA, respectively. The output power generated was sufficient to instantaneously light a full screen liquid crystal display (LCD). The Ti-mesh/BTO-based PENG device is lead-free and does not have a toxic dispersion enhancer. It is a promising candidate for self-powered sensors and biomedical device applications.

Effect of Capital Structure on the Performance of Listed Consumer Goods Companies in Nigeria

Abstract: Managers of corporate entities are mostly in confrontation with the problem of; what combination of capital structure (equity and debt) will maximize returns and value of their firms? The study, therefore, aims at assessing the effect of capital structure on the financial performance of listed Consumer goods companies in Nigerian. All consumer goods companies quoted on the Nigerian Stock Exchange are considered the population for this study while seven (7) out of these firms whose accounting year-ends 31 December are considered as the sample. Secondary data was utilized from the annual financial reports of the sampled firms from the year 2008-2013, which was obtained from African Financial website and official website of Nigerian Stock Exchange. The study used ex-post facto research design to examine the relationship between independent and dependent variables while controlling for other variables. Descriptive statistics, correlation, and hierarchical multiple regression analyzes were carried out to test the hypotheses developed in the study. The study found that there is a positive and significant relationship between firm’s capital structure and corporate financial performance. The study specifically found that short-term debt (STD) has no significance positive effect on return on equity (ROE) while Long-term debt (LTD) has positive relation and significant effect on ROE. The study recommends that firms should consider the mixture of equity and debt since they are major determinants of corporate performance. Authorities concerned should create an enabling business environment for companies (especially those with low capital) so as to have access to long-term debts to finance their operations and improve performance in the shortrun, instead of using high short-term debts to cushions for financing and profitability problems.

Probing the interaction of caffeic acid with ZnO nanoparticles.

Abstract: The binding of ZnO nanoparticles (NPs) and caffeic acid (CFA) was investigated using fluorescence quenching, UV/vis absorption spectrscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) at different temperatures. The study results indicated fluorescence quenching between ZnO NPs and CFA rationalized in terms of a static quenching mechanism or the formation of non-fluorescent CFA-ZnO. From fluorescence quenching spectral analysis, the binding constant (K(a)), number of binding sites (n) and thermodynamic properties were determined. Values of the quenching (K(SV)) and binding (K(a)) constants decrease with increasing temperature and the number of binding sites n = 2. The thermodynamic parameters determined using Van't Hoff equation indicated that binding occurs spontaneously involving the hydrogen bond, and van der Waal's forces played a major role in the reaction of ZnO NPs with CFA. The FTIR, TEM and DLS measurements also indicated differences in the structure, morphology and size of CFA, ZnO NPs and their corresponding CFA-ZnO.

Design and Analysis of Deep Drawing Process on angular Deep Drawing Dies for Different Anisotropic Materials

Abstract: Deep drawing process is a significant metal forming process used in the sheet metal forming operations. From this process, complex shapes can be manufactured with fewer defects. Deep drawing process has different effectible process parameters from which an optimum level of parameters can be identified so that an efficient final product with required mechanical properties will be obtained. The present work is to evaluate the formability of different metal sheets using deep drawing process. In which effects of different sheets and die/blank holder angle on deep drawing process observed for sheet metal of 0.8mm of SS304 and Brass and 0.9 mm of Al. The experiments were performed by designing the deep drawing tools such as die, blank holder, and punch. In addition, the numerical simulations are performed for deep drawing of cylindrical cups using three levels of previously mentioned. Punch forces and dome heights are evaluated for all the conditions. From this work, the formability for different metal sheets is observed for angular geometries of deep drawing tools. Moreover, it is observed that strain formation is more for the brass sheet and stress is more for aluminium sheets.

Anti-mycobacterial, Antimicrobial and Phytochemical Evaluation of Pulicaria crispa and Scoparia dulcis Plant Extracts

Abstract: Aim: To examine the antimicrobial activity and evaluate the anti-mycobacterial potency of Pulicaria crispa and Scoparia dulcis whole plant extracts in solvents of different polarities (n-hexane, ethyl acetate and methanol. Study Design: Assessing the anti-microbial and anti-Mycobacterium tuberculosis activity of two Nigerian medicinal plants which have been reported according to folklore for treatment of various Original Research Article Adebiyi et al.; JAMPS, 7(4): 1-11, 2016; Article no.JAMPS.25199 2 ailments including respiratory tract infections. Place and Duration of Study: The experiment was conducted at the Chemistry Department of Ahmadu Bello University, Zaria, Nigeria and at the National Institute for Pharmaceutical Research and Development, Abuja, Nigeria between November 2014 and September 2015. Methodology: The standard pan sensitive tuberculosis reference strain (H37Rv), eleven bacterial and four fungal clinical isolates were used. Methanol, Ethyl Acetate and Hexane extracts of Scoparia dulcis and Pulicaria crispa (whole plants) were tested at 0, 20 and 40 μg/ml using the Microplate Alamar Blue Assay. The minimum inhibitory, minimum bactericidal and minimum fungicidal concentrations of each solvent extract were assessed. Phytochemical analysis was also performed. Results: Phytochemical compounds obtained in the methanol extract fractions where alkaloids, balsams, cardiac glycosides, glycosides, phenols, steroids and tannins in Scoparia dulcis (Linn), while extracts of Pulicaria crispa showed the presence of alkaloids, balsams, cardiac glycosides, flavonoids, glycosides, phenols, tannins and terpenoids. Saponins were detected in the n-hexane fractions for both plants but only appeared in the semi-polar fractions of Scoparia dulcis (Linn). Microplate Alamar Blue Assay (MABA) used for sensitivity study of Mycobacterium tuberculosis with 10 μg/ml rifampicin revealed that the n-hexane extract of Puliaria crispa and Scoparia dulcis gave 48.44±0.75, 12.14±0.02 mm zones of inhibition respectively, whereas the methanol and ethyl acetate extracts gave a 24.10±1.35 mm and 17.00±0.91 zones of inhibition for Puliaria crispa and Scoparia dulcis respectively in comparison to 33.70±0.64 mm obtained from the control. The minimal inhibitory content (MIC) of the methanol and n-hexane extracts for Pulicaria crispa were recorded at 8.01±1.70 and 10.03±1.33, while the MIC values for the ethyl acetate and n-hexane extracts of Scoparia dulcis was 12.03±0.86 and 20.40±0.24. The MIC value recorded for rifampicin was 0.38±1.40. Conclusion: The results obtained suggested that the studied plants possess anti-tuberculosis and selective antimicrobial activities with the major activity tailored to the phyto-constituents.

Seasonal Rainfall–Runoff Variability Analysis, Lake Tana Sub-Basin, Upper Blue Nile Basin, Ethiopia

Abstract: Lake Tana sub-basin of Abbay (Blue Nile) River Basin is located in the high land areas with unimodal rainy season with spatial and temporal variation of rainfall and runoff. Depending on available resources, there are many developmental plans and projects which seek the wise planning and management of water resources considering both low flows and floods. The seasonal streamflow variability analysis of the basin was performed with recorded meteorological and hydrological data. The four seasons of the year are considered for seasonality analysis. The rainfall variability is analysed using seasonality and variability measures of coefficient of variation, seasonal relative rainy days and seasonal rainfall intensity. The rainfall variability is more related with latitude and longitude. Spatial and temporal seasonal rainfall variation is analysed from daily rainfall data. Seasonal runoff and streamflow variations are also analysed using HEC-HMS hydrological model to generate runoffs at required and selected points to detect spatial variation. Runoff variation for catchments with gauged stations was analysed from recorded time series streamflow data. Runoff coefficient is taken as a variability index for both generated and recorded streamflows. The runoff coefficient ranges from 0 to 1. The range is high in the dry seasons and less in the wet seasons. The average runoff coefficient value of the basin is 0.28 ranging from 0.18 to 0.36. The average seasonal runoff coefficient value from generated runoffs is 0.45, 0.3 for dry and 0.6 for wet seasons. From the results, it is shown that runoff coefficient is more dependent on antecedent soil wetness condition, land use and land covers. Catchments were categorised spatially and temporally as vulnerable, moderately vulnerable and less vulnerable to runoff based on the analysis. From hydrological data variability tests, it is clearly observed that seasonal time series data are not homogeneous, stationary and independent. Minimum flows are more stationary and homogeneous than mean and maximum flows.

Failure Prediction in Fiber Metal Laminates for Next Generation Aero Materials

Abstract: In aerospace industry, there is huge demand for low density and low cost materials with better mechanical properties. In this view, there are many researchers developed new materials interms of composites. Similar manner, the present paper also aimed to produce a new approach for cost effective materials of 3D weaved glass fiber metal laminates (FML) with different compositions using a numerical study. A method for the simulation of progressive delamination based on de-cohesion elements has been presented. De-cohesion elements are placed between layers of solid elements that open and shear in response to the loading situation. The onset of damage and the growth of delamination are simulated without previous knowledge about the location, the size, or the direction of propagation of the de-laminations. A softening law for mixed-mode delamination that can be applied to any interaction criterion is also proposed. The constitutive equation proposed uses a single variable, the maximum relative displacement, to track the damage at the interface under general loading conditions. The material properties required to define the element constitutive equation are the inter-laminar fracture toughness's, the penalty stiffness, and the strengths.

Formability analysis of aluminum alloys through deep drawing process

Abstract: Deep drawing process is a significant metal forming process used in the sheet metal forming operations. From this process complex shapes can be manufactured with fewer defects. Deep drawing process has different effectible process parameters from which an optimum level of parameters should be identified so that an efficient final product with required mechanical properties will be obtained. The present work is to evaluate the formability of Aluminum alloy sheets using deep drawing process. In which effects of punch radius, lubricating conditions, die radius, and blank holding forces on deep drawing process observed for AA 6061 aluminum alloy sheet of 2 mm thickness. The numerical simulations are performed for deep drawing of square cups using three levels of aforesaid parameters like lubricating conditions and blank holding forces and two levels of punch radii and die radii. For numerical simulation a commercial FEM code is used in which Hollomon's power law and Hill's 1948 yield criterions are implemented. The deep drawing setup used in the FEM code is modeled using a CAD tool by considering the modeling requirements from the literature. Two different strain paths (150x150mm and 200x200mm) are simulated. Punch forces, thickness distributions and dome heights are evaluated for all the conditions. In addition failure initiation and propagation is also observed. From the results, by increasing the coefficient of friction and blank holding force, punch force, thickness distribution and dome height variations are observed. The comparison has done and the optimistic parameters were suggested from the results. From this work one can predict the formability for different strain paths without experimentation.

New idea of suppressing free surface vortex during tapping liquid steel from converter

Abstract: During tapping liquid steel from a converter to a ladle, slag may carry over due to a formation of free surface vortex. Such vortex should be suppressed in order to minimize contamination of the steel by slag. In the present study, a new idea is proposed to minimize the vortex formation by applying dual tapping hole system. The idea was tested using a rectangular shape water vessel with dual tapping holes, supplemented by a numerical simulations, in order to evaluate feasibility of the dual tapping hole system. Both the water model experiment and the numerical simulation showed similar tendencies that the dual tapping hole system is promising to prevent the vortex formation. Experimental results showed that the free surface vortex formation is highly sensitive to shape and configuration of the nozzle. From the numerical simulation, flow characteristics were obtained, and vortex canceling between two nozzles is confirmed. Effect of dual tapping hole increased with increasing distance between two holes in the present experimental condition. Finally, a 1/7.8 scale-down water vessel simulating a real converter was employed in order to confirm the validity of the above findings. The result showed almost the same tendencies with the previous findings.

Combining EDF and LST to enhance the performance of real-time task scheduling

Abstract: Real time system is a system in which the computation not only depends on producing a correct output, but the output should be delivered within predetermine timing constraint called deadline. As humans, we handle scheduling issues every day. For example, a student must accomplish homework by the appropriate due date, a professor must complete the rough draft of a paper by the submission date, etc., where we have only one task to accomplish, meeting that deadline probably would be very simple. Our lives, however, contain many tasks that have deadlines tax forms, car inspections, meetings, classes, etc. Thus, we must use some sort of scheduling technique to “juggle” our various tasks, so that they all are completed by their appropriate deadlines. As a result, many scholars develop different static and dynamic scheduling algorithms, which are best suited for both uniprocessor and multiprocessors. This paper work will focus on proposing a new dynamic scheduling algorithm. Because, it is found that the well-known uniprocessor dynamic scheduling (EDF (earlier deadline first) and LLF (least slack time first)) algorithms have many context switching and many probability of overhead occurrence (deadline-tie and laxity-tie respectively) which will degrade the performance of the whole system. The paper proposes a dynamic scheduling algorithm that has low context switching and totally reduce the probability of overhead occurrence by combining the deadline and slack to give priority for each task in the ready queue.

Mobile healthcare services adoption

Abstract: Recent penetration of mobile technologies opens exciting potential for e-healthcare in low-income countries - e-healthcare services can now reach the populations of rural and far away locations in a cost effective and timely manner. The final challenge however rests on successful user acceptance of the technologies of e-healthcare, which we investigate in this work. Our research enhance the basic TAM model with two additional context appropriate constructs from extant research to arrive at an extended TAM model that is suitable for understanding e-healthcare adoption in low-income countries. We operationalise the model with the help of a validated survey questionnaire in the health extensions workers of Ethiopia, a Sub-Saharan low-income country. Our result shows that compatibility positively affects adoption intention. These results demonstrate that inclusion of additional constructs of compatibility and network quality enhances the richness of the model and explain adoption intention in a more effective manner.

From 3GPP LTE to 5G: An Evolution

Abstract: All-IP network architecture is fast becoming a norm in mobile telecommunications. The International Telecommunications Union—Radio communication sector (ITU-R) recognizes a technology as 4G after haven met the International Mobile Telecommunications Advanced (IMT-A) specification of a minimum of 100 Mb/s downlink data rate for high mobility and 1 Gb/s for low mobility. The Long Term Evolution specified by the 3GPP, provides a minimum downlink data rate of 100 Mb/s and marks a new beginning in Radio Access Technologies (RATs). It also notably implements an all-IP network architecture, providing higher data rates, end-to-end Quality of Service (QoS) and reduced latency. Since the first release of the LTE standard (3GPP release 8), there have been a number of enhancements in subsequent releases. Significant improvements to the standard that enabled LTE to meet the IMT-A specifications were attained in release 10, otherwise known as LTE-Advanced. Some of the enhancements such as the use of small cells (known as femtocells) are envisioned to be the basis of fifth generation (5G) wireless networks. Thus, it is expedient to study the LTE technology and the various enhancements that will shape the migration towards 5G wireless networks. This paper aims at providing a technical overview of 3GPP LTE. With a brief overview of its architecture, this paper explores some key features of LTE that places it at the forefront in achieving the goals of wireless access evolution, enabling it to become a key element of the ongoing mobile internet growth. The migration to 5G may be radical, thus some enabling technologies that will shape the 5G cellular networks are also examined.

Ordered Successive Interference Cancellation for Maximum Throughput in Multi Stream MIMO using different Modulation Schemes

Abstract: Objective: In this article performance evaluation of Multi Input Multi Output (MIMO) system using Alamouti and Spatial multiplexing with different modulation schemes is studied and in case of multi stream MIMO interference is suppressed by means of interference cancellation. Methods: In communication systems without any additional bandwidth MIMO offer considerable increase in data throughput and link range. In this paper performance of MIMO with Almouti code and spatial multiplexing is evaluated by means of BER (Bit Error Rate) performance under PSK and QAM modulation schemes. Findings: In this paper Minimum Mean Square Equalizer (MMSE) and Zero Force (ZF) equalizers are used for the estimation of received symbols. Estimates of MMSE and ZF are used for the Successive Interference Cancellation (SIC). In this article based on the received signal power an ordered successive interference cancellation is developed for maximum throughput. Improvements: The developed OSIC is tested with different modulation schemes and the performance are figured out for both SIC and OSIC.

Queueing Technique for Ebola Virus Disease Transmission and Control Analysis

Abstract: Objective: The outbreak of Ebola Virus Disease (EVD) in different countries, especially the West African nations has been ravaging human lives and the economy. The ugly situation calls for urgent provision of sound EVD control measures. Methods/ Statistical Analysis: This paper proposes the queueing technique as a promising and efficient mathematical approach for the study of EVD transmission and control. It highlights the queueing theory governing equation and applies the theory to EVD problem. Findings: The application of the technique to the Guinea 2014 EVD outbreak indicates that the use of two quarantine centres to combat the outbreak would have served as an adequate control measure. This technique can be used to manage the manpower and material resources in the combat against EVD outbreak. Applications/Improvements: This approach brings to fore the possible use of queueing technique in the analysis of EVD outbreak. Transmission and control in other countries ravaged by EVD could be studied using queueing network models.

DDoS Attacks and Their Types

Abstract: Billions of people rely on internet to discover and share ideas with the world. However, the websites are vulnerable to deliver the attacks, preventing people to access them. The recent study of global surveys showed that DDoS Attacks evolved in strategy and tactics. A Distributed Denial of Service (DDoS) attack is a new emerging bigger threat that target organization’s business critical services such as e-commerce transactions, financial trading, email or web site access. A DDoS attack is a large-scale, coordinated attack on the availability of services of a victim system or network resource, launched indirectly through many compromised computers on the Internet. To create attacks, attackers first discover vulnerable sites or hosts on the network. Then vulnerable hosts are exploited by attackers who use their vulnerability to gain access to these hosts. This chapter deals with the introduction, architecture and classification of DDoS Attacks.

Some applications via fixed point results in partially ordered S b $S_{b}$ -metric spaces

Abstract: In this paper we give some applications to integral equations as well as homotopy theory via fixed point theorems in partially ordered complete $S_{b}$ -metric spaces by using generalized contractive conditions. We also furnish an example which supports our main result.

Effect of Ba Co-Doping on Sr5(PO4)3Cl:Ce3+ Blue Emitting Phosphor Application for White Light Emitting Diodes

Abstract: Ce3+-activated Sr5-2x-yBay(PO4)3Cl:xCe3+,xNa+ phosphors were synthesized via the solid statereaction methods. The substitution of Ba2+ for Sr2+ ions was confirmed by Raman spectra. The broadest Raman width in Sr2.45Ba2.45(PO4)3Cl:Ce3+ phosphor supported its highest disorder of the host lattice, leading to the emission spectral broadening with a half width of 95.5 nm due to the larger variation in crystal filed strength. The thermal stability of the luminescence was evaluated by the temperature-dependent luminescence intensity. The simulating a spectra of blue-emitting Sr2.45Ba2.45(PO4)3Cl:0.05Ce3+,0.05Na+ and orange emitting Sr3SiO5:Eu2+ phosphors as light converters, an intense white GaN-based near-UV-LED (400 nm) was exhibit good color-rendering index Ra of 90.8 at a correlated color temperature of 6473 K and CIE coordinates of (0.3165, 0.3051). These characteristics makes Sr2.45Ba2.45(PO4)3Cl: 0.05Ce3+,0.05Na+ should be a promising blue-emitting phosphors for the production of white light in phosphor conversion white-LEDs.

Credit Risk Management and Customer Satisfaction in Tier-one Deposits Money Banks: Evidence from Nigeria

Abstract: This study investigates the effect of credit risk management on customer satisfaction in tier-one deposits money banks in Adamawa state, Nigeria. The objectives of the study were to examine relationship between credit risk management and customers’ satisfaction and to assess the relationship between credit risk management and credit appraisal process. The study surveyed 384 selected customers from three tier-one deposits money banks in Adamawa state, Nigeria. Purposive sampling was used in selecting the banks and simple random sampling was used in administering the questionnaire to the customers. Descriptive and inferential statistics were used to analyze and interpret the data collected. The study found that there is positive and significant relationship between credit risk management and customer satisfaction and the regression results showed that 49% of the variability in customer satisfaction can be explained by credit risk management. The study also found significant positive correlation between credit appraisal process and credit risk management, with 81% of the variability in credit appraisal process explained by credit risk management. The study recommends that despite the positive relationship between credit risk management and customer satisfaction, there is need for banks’ management to pay attention to other factors that will contribute to customer satisfaction other than granting of credit facilities. At intervals, Banks should conduct seminars or training to update their staff on current credit guidelines issued by the regulatory authorities to enhance their knowledge on credit risk management with a view of ensuring customer satisfaction. Keywords: Credit Risk Management; Customer Satisfaction; Deposits Money Banks; Tier-one; JEL Classifications: M400, M30