Browsing by Author "Annan, E."

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Ag2CO3-halloysite nanotubes composite with enhanced removal efficiency for water soluble dyes
(Heliyon, 2019-06-13) Nyankson, E.; Agyei-Tuffour, B.; Annan, E.; Yaya, A.; Mensah, B.; Onwona-Agyeman, B.; Amedalor, R.; Kwaku-Frimpong, B.
The release of water soluble dyes into the environment is an utmost concern in many countries. This paper presents the effects of Ag2CO3-halloysite composites on the efficient removal of water soluble dyes. In this study, NaHCO3 solution was added dropwisely to halloysite nanotubes (HNTs) dispersed in aqueous AgNO3 to form Ag2CO3-HNTs composite. The synthesized Ag2CO3-HNTs composite was characterized with Diffused Reflectance Spectroscopy (DRS), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), Scanning Electron Microscopy- Energy Dispersive Spectroscopy (SEM-EDX) and Fourier Transform Infra-Red (FT-IR) spectroscopy. The photocatalytic activity and the adsorption capacity of Ag2CO3-HNTs on methylene blue and rhodamine b dyes were dependent on pH and the amount of HNTs used in the synthesis. The photodegradation efficiency of Ag2CO3 was lower when compared with that of the composite material. This observation is due to the reduction in the electron-hole recombination with the HNTs acting as electron trapping site and the enhanced aqueous dispersity of Ag2CO3-HNTs. The enhanced adsorption of water soluble dyes by the Ag2CO3-HNTs resulted from the electrostatic attraction of cationic dyes to the surface of the HNTs (negatively charged). The Ag2CO3-HNTs therefore removed dye pollutants through a combination of photocatalytic and adsorption processes. The results obtained during the study confirmed the potential application of Ag2CO3-HNTs composite in water treatment technologies.
Application of clay ceramics and nanotechnology in water treatment: A review
(Cogent Engineering, 2018-07) Annan, E.; Agyei-Tuffour, B.; Bensah, Y.D.; Konadu, D.S.; Yaya, A.; Onwona-Agyeman, B.; Nyankson, E.
The increasing demand to provide clean water for drinking has brought to the fore the importance of seeking other materials with the ability or combined effect with other materials to purify water. Clay ceramics are known to be natural and also easily engineered porous-structured materials. Review papers on water filtration over the last decade have been on specific mechanisms or technologies. This review paper presents a single platform which provides information encapsulating all these technologies. This paper highlights water contaminants, and their various treatment technologies. The effectiveness of these technologies are evaluated via scholarly documented peer-reviewed papers. Moreover, the discussions are interspersed with the World Health Organization’s (WHO) standard for various contaminants along with the exploration of the efficiency of clay minerals as potent water filtration material. Finally, current trends in application of nanotechnology in water purification systems are also highlighted. These technologies include adsorption, microbial disinfection, and photocatalysis.
Characteristics Of Stabilized Shrink-Swell Deposits Using Eggshell Powder
(2013) Nyankson, E.; Agyei-Tuffour, B.; Annan, E.; et al.
Shrink-swell soils expand and heave or contract and crack during periods of high and low moisture content. The expansion and contraction cause the lifting and or sinking of structures, crack development, and eventual collapse of engineering structures. The need to stabilize such plastic soils to improve their load-carrying capacities cannot be overemphasized. Therefore in this article, the effect of lime contained in eggshells and its application in the stabilization of shrink-swell soils have been explored. 4wt% and 8wt% of eggshell powder were mixed with equal masses of two different soil samples from Dodowa (DD) and Adalekope (AD) in Ghana. The samples were characterized with X-ray fluorescence (XRF), Plasticity Index analysis (PI), Free Swell Index (FSI), pH test, and a grading test. The x-ray fluorescence results showed that eggshell contains about 52wt% of CaO, which is largely responsible for soil stabilization. The sample mixed with 8wt% eggshell powder showed a decreased PI, FSI, and a high silt/clay fraction. The results obtained have been discussed and can influence the application of eggshell powders for large-scale stabilization of expansive soils.
Dispersion and functionalization of single-walled carbon nanotubes (SWCNTS) for nanocomposite applications
(EDP Sciences, 2016) Yaya, A.; Tekley, A.; Annan, E.; Efavi, J.K.; Tiburu, E.K.; Onwona-Agyema, B.; Jensen, L.R.
We present an easy and reliable method of functionalizing and dispersing single-walled carbon nanotubes (SWCNTs) for nanocomposite production. This was achieved via a mixture of the concentrated acids HNO3/H2SO4, followed by sonication in appropriate solvents (Ethanol, Acetone and/or Dimethylformamide). SWCNTs were functionalized to attach carboxylic moieties on the walls of the nanotubes, which aided in the production of SWCNTs suspensions in acetone, ethanol and dimethylformamide in which nanotubes remained dispersed for a period of two (2) weeks. Energy dispersion analysis (EDS), scanning electron microscopy (SEM) and Raman spectroscopy were used to characterize the functionalized SWCNTs. © EDP Sciences, 2017
Eco-friendly green composites reinforced with recycled polyethylene for engineering applications
(Springer link, 2023) Annan, E.; Mensah, J.K.; Arthur, E.K.; et al.
Abstract Polyethylene (PE) and cement are industrial products that promote environmental pollution. These products when exposed on the landfill have tremendous effects on the lives of humanity and other living creatures, including animals. Therefore, this research presents the results of experimental and theoretical modeling of green composites (without the inclusion of cement) reinforced with recycled polyethylene waste for applications in the Mechanical and Civil Engineering industry. The composites are produced using different weight fractions of laterite and molten PE mixed homogeneously to produce unique green composites with excellent mechanical properties. The green composite with 40 wt.% laterites and 60 wt.% PE exhibited the highest compressive strength, flexural strength and fracture toughness of 25 MPa, 7.3 MPa and 0.6M Pa√m, respectively. Additionally, the green composite recorded maximum yield stress of ∼2MP. The maximum yield stress of the green composites falls under the minimum range of yield stress for traditional concrete structures. The SEM images reveal evidence of bonding and ligament bridging in the green composites reinforced with 40 wt.% laterites and 60 wt.% PE. The probability distribution plots show that the polyethylene in the green composites follows the Weibull distribution with low Anderson Darling Statics and p-values greater than significance level of 5%.
Fabrication, Properties, and Performance of Polymer-Clay Nanocomposites for Organic Dye Removal from Aqueous Media
(Adsorption Science & Technology, 2023) Tsekpo, Y.M.; Appiah, A.N.S.; Damoah, L.N.W.; Amusah, D.; Annan, E.
Methylene blue dye (MB dye) is a harmful contaminant for wastewater streams of industries and is harmful to human and aquatic life. An ecofriendly sugar templating process was used to generate porous bentonite/polydimethylsiloxane (PB) and porous magnetite nanoparticles/bentonite/polydimethylsiloxane (PBNP) composite absorbents to remove MB dye in this study. During the infiltration of PDMS solution into the sugar template in the vacuum chamber, bentonite and magnetite particles were integrated on the surface of the PDMS, and the porous structure was generated during the leaching out of sugar particles in water. The absorbents were characterized using Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The absence of the methyl bond at 2924 cm-1 and phenol bond at 3325 cm-1 in the FTIR spectra of the formed membrane proves that the food grade sugar was completely removed. The SEM images confirm that porosity was achieved as well as uniform mixing of the in the formation of composite. MB dye was effectively removed from wastewater using the as-prepared composite as absorbent. The removal efficiencies of the composite PBNP and PB were ~91% and ~85%, respectively. The experimental data was applied to pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models as well as the Dubinin-Radushkevich, Harkins-Jura, and Elovich models for the adsorption isotherm. The data was found to fit the pseudosecond-order and Elovich models, respectively. The results show that the presence of magnetite nanoparticles improved MB dye removal significantly.
Industrial Applications of Clay Materials from Ghana - A Review
(Oriental Journal of Chemistry, 2018-08) Asamoah, R.B.; Nyankson, E.; Annan, E.; Agyei-Tuffour, B.; Efavi, J.K.; Kan-Dapaah, K.; Apalangya, V.A.; Damoah, L.N.W.; Dodoo-Arhin, D.; Tiburu, E.K.; Kwofie, S.K.; Onwona-Agyeman, B.; Yaya, A.
Clay minerals are phyllosilicate groups naturally found in soils in all parts of the world. They have proven to be among the most essential industrial minerals because of their unique physicochemical properties and versatile applications within a wide range of fields including ceramics, construction, and environmental remediation, biomedical as well as cosmetics. Clay minerals are also primary to the production of other materials such as composite for secondary applications. In Ghana, clay mineral deposits are commonly found in several areas including soil horizons as well as geothermal fields and volcanic deposits, and are formed under certain geological conditions. This review seeks to explore the geographical occurrence and discusses the current uses of various local clay materials in Ghana in order to highlight opportunities for the utilization of these materials for other applications.
Investigating Triaxial Electrical Properties of Ceramic Composites for Electroporcelain Insulators
(Journal of Ceramic Processing Research, 2018-04) Dowuona, A.N.N.; Yaya, A.; Nyankson, E.; Efavi, J.K.; Damoah, L.N.W.; Dodoo-Arhin, D.; Apalangya, V.; Annan, E.; Tiburu, E.K.; Onwona-Agyeman, B.; Tomiczek, B.
Four porcelain composites comprising kaolin (27-37%), beach sand (20-24%), ball clay (13-18%) and feldspar (25-40%), were formulated and characterized using powder XRD, SEM and particle size distribution analysis in order to determine their potential for use as electroporcelain insulators. Chemical, mechanical and electrical properties were also evaluated. Each of the formed samples were compressed at 200 MPa and sintered at 1250 o C for 1 hour. Bending strength results of the porcelain bodies showed increase in bending strength with reduction in particle sizes. An increase in dielectric strength was found for samples with a higher felspar content. The XRD pattern for all the sintered samples showed the presence of quartz and mullite phases in the body at different intensities. Samples with lower particle sizes showed similar electrical and mechanical properties to commercially available electroporcelains albeit at a cheaper cost of production.
Nanostructured TiO2 and their energy applications-a review
(ARPN Journal of Engineering and Applied Sciences, 2013-10) Nyankson, E.; Agyei-Tuffour, B.; Asare, J.; Annan, E.; Rwenyagila, E.R.; Konadu, D.S.; Yaya, A.; Dodoo-Arhin, D.
Environmental sustainability and reliable energy sources are major challenges facing the world in the 21st century. Ironically, the solution to these taunting problems may lie in something small. Nanomaterials with attractive chemical and physical properties are being explored for potential uses in energy and environmental applications. Nanostructured Titanium dioxide (TiO2) has gained considerable attention in the energy and environment sectors due to their brilliant prospects in photo catalysis, solar cells, environmental pollution treatment and its use in solar water splitting for the production of H2. There are many processing techniques such as; the Sol gel (SG), the hydro-thermal (HT), the solvothermal (ST) and chemical vapor deposition (CVD) which are used in the production of nanostructured TiO2 for the applications stated above. This review aims at examining the general characteristics of nanostructured TiO2 and its application in dye sensitized solar cells, photocatalytic splitting of water and solid state hydrogen storage devices. The analysis is meant to demystify the anxiety associated with the application of nanomaterials in solving everyday challenges in the energy and environmental sectors. © 2006-2013 Asian Research Publishing Network (ARPN).
Perspectives of nurses regarding pain assessment and management during routine infant vaccination in Ghana
(John Wiley and Sons Inc, 2023) Annan, E.; Ramukumba, T.S.; Stevens, B.J.
Abstract Aim To explore the perspectives of nurses regarding pain and its management during routine infant vaccination at the Child Welfare Clinics in Ghana. Design Qualitative descriptive design. Methods Qualitative in depth, in-person interviews using a semistructured interview guide were conducted with 19 Registered Nurses who were were purposively sampled from three selected Child Welfare Clinics in hospitals in the Greater Accra Region of Ghana, The Tesch cotent analysis procedure was followed for the analysis of interview data. Results Nurses were aware that the injections they give infants are painful. They described how infants exhibit certain behaviours to express pain. Although nurses support infant pain management during vaccination, they rarely use evidenced-based pain interventions.
The physico-mechanical influence of dehydroxylized activated local kaolin: A supplementary cementitious material for construction applications
(Case Studies in Construction Materials, 2019-11-05) Marfo, N.K.; Dodoo-Arhin, D.; Agyei-Tuffou, B.; Nyankson, E.; Obada, D.O.; Damoah, L.N.W.; Annan, E.; Yaya, A.; Onwona-Agyeman, B.; Bediako, M.
This work presents the effect of partially replacing metakaolin with Portland limestone cement to produce mortars for construction. Teleku Bokazo kaolin was explored as a SCM in the production of mortars. The hydration product between Portland limestone and metakaolin was studied. The kaolin was heat treated to form metakaolin and partially used to replace Portland limestone cement (PLC) in mortars to explore the optimum replacement and its mechanical and durability effect. The samples were characterized using X-ray diffraction (XRD) for phases and crystallinity of the kaolin. Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) gave information on the functional groups formed during the hydration and structure and surface morphology respectively. The pastes and mortars produced were subjected to setting time, water absorption, flexure and compression strength test. The mechanical properties were observed to increase with increasing metakaolin replacements. Therefore, from the results obtained, it is suggested that 20 % replacement of Portland limestone cement with Teleku Bokazzo metakaolin can be very suitable for construction applications.
Physico-mechanical properties of bauxite residue-clay bricks
(ARPN Journal of Engineering and Applied Sciences, 2012-12) Annan, E.; Agyei-Tuffour, B.; Damoah, L.N.W.; Konadu, D.S.; Mensah, B.
This study is focused on consolidating knowledge on the application of Bauxite residue in the building industry. X-Ray fluorescence (XRF) reports of the bauxite and bauxite residue are given. Physico-mechanical properties of red mud (RM)-Clay (AC) bricks are also presented. The RM-AC bricks have compositions; 90%-10%, 80%-20%, 70%-30%, 60%- 40%, 50%-50%, 40%-60% prepared and fired at sintering temperatures 800°C, 900°C and 1100°C. The experimental results obtained showed that ateach of the three stated sintering temperatures, bulk density increases as apparent porosity and water of absorption reduces. Bulk densities computed were within the range (1.3-1.8)g/cm3 at 11000°C sintering temperature. Maximum flexural strength was found to be associated with 50%-50% (Red mud-clay) composition at 1100°C. And the compressive strength (3.2-12.5) MPa range found for all batches at 1100°C sintering temperature. Generally, flexural and compressive strengths were increased with higher sintering temperature. The results obtained for various characterization analysis compares well with literature and hold potential in bauxite residue eco-friendly application as fired brick ©2006-2012 Asian Research Publishing Network (ARPN).
Recent Trends in The Use of Nanomaterials for Wastewater Treatment: A Minireview
(The 2nd International Conference on Multidisciplinary Engineering and Applied Sciences, 2023) Saliu, H.; Annan, E.; Bello, A.
Man’s life depends on water in many ways. Worldwide industrialization and water resource exploitation have accelerated during the past few decades. Heavy metals and other pollutants, including effluent wastewater, are released into water streams as a result of industrial activity all over the world. Due to their toxicity, these contaminants are thought to be hazardous to both man and the environment and lower the quality of water. Even in low concentrations, heavy metals can be extremely harmful to living things. Numerous methods have been investigated for treating wastewater for many years. However, the discipline of nanotechnology has recently shown the world how to solve the issue of wastewater treatment using creative and practical methods.
Reinforcement of cement mortar with recycled polyethylene waste for construction applications
(JOURNAL OF COMPOSI T E MATERIALS, 2021) Flomo, M.K.; Azeko, S.T.; Arthur, E.K.; Kukurah, J-D.; Mustapha, K.; Annan, E.; Agyei-Tuffour, B.
This current research work combines both experimental and theoretical study of the impact of cement mortar reinforced with recycled polyethylene waste for applications in the construction industry. The work explores incorporating low density polyethylene (LDPE) waste into cement mortar to improve its fracture toughness and flexural strength with balanced compressive strength. Different volume fractions (0, 5, 10, 15, 20, 30, and 40%) of the powdered LDPE were mixed with cement and the density, compressive strength, flexural strength, and the fracture toughness were observed under different testing conditions. All specimens were tested after curing of 7, 14, and 28 days. The results show that there was 6% increase in the fracture toughness at 5 vol. %, 7% increase at 10 vol. %, and 24% increases at 20 vol. % of LDPE. Also, it was observed that the weight and compressive strength decreased with increasing volume fraction up to 40 vol. % of LDPE waste. The results for the survival/failure probability show that the PE-mortar composites with PE volume percentages up to 20 vol. % had the highest survival probability. The composite with this volume percentage can withstand crack up to 6mm, with a survival probability of 0.6.
A Review of a Collaborative Online International Learning
(International Journal of Engineering Pedagogy, 2020-05-21) Annan, E.; Appiah-Kubi, P.
Abstract—Globalization has exacerbated the need for engineers who are capable of working in a cross-cultural environment. Multinational companies continuously seek for engineers who are interculturally competent and capable of conducting business successfully in a cross-cultural environment. However, the skills required to be successful in a multicultural environment are difficult to be taught in the traditional classroom. One of the most effective approaches to acquiring intercultural competency skills is through experiential learning. It is, therefore, not surprising that most colleges all over the world are devoting resources towards the internationalization of their classrooms and the campus community. This ensures that students are provided with a diverse environment, so they can learn from, and about diverse cultures to enhance their intercultural competency skills. Another effective approach is the study abroad programs, which require students to travel to different countries. However, these approaches require a lot of resources that may not be available to the less fortunate students. Therefore, a more cost-effective approach, such as Collaborative Online International Learning (COIL), is receiving a lot of attention in recent years. In this study, some engineering technology students participated in a 8-week long COIL program with materials engineering students from different languacultural and geographical regions. This study reviews the results and compares the performance of the COIL students with those who were not involved in the study. It was observed that the COIL teams performed significantly better on the project work. In addition, 70% (of the 11 students from the University of Ghana) and 85% (of the 20 students from the University of Dayton) respectively reported that the collaboration was either effective or very effective
Statistics of flow and the scaling of ceramic water filters
(Journal of Environmental Engineering (United States), 2014-07) Annan, E.; Mustapha, K.; Odusanya, O.S.; Malatesta, K.; Soboyejo, W.O.
According to the World Health Organization (WHO), there was an increase in the number of people that have access to safe drinking water between 2006 and 2010. Such trends can be accounted for partly by the increasing usage of ceramic water filters that can remove microbial pathogens from water. However, the initial flow rates in such filters are often limited to ranges between 1 and 3 L/h. In this paper, six frustum-shaped ceramic water filters of the same clay:sawdust composition were tested. Each ceramic water filter was filled with water and allowed to filter 20 times. Each time, the flow rate and water level were measured for a consecutive 12 h. Permeability values were estimated for each run of the ceramic water filters. Statistical analysis was performed on flow rates (in the first hour), mean flow rates, and estimated permeability values. The flow rate values (in the first hour) for the six ceramic water filters were found to be between 1.4 and 3.0 L/h. An effective permeability was obtained for ceramic water filters with a range of microscale and nanoscale pore sizes. The statistical variations in the flow rates and effective permeabilities were elucidated along with the potency of a multiple ceramic water filter system for scale-up studies in serving communities that need portable water. © 2014 American Society of Civil Engineers.
Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment
(Hindawi, 2021) Annan, E.; Arkorful, G.K.; Konadu, D.S.; Asimeng, B.; Dodoo-Arhin, D.; Egblewogbe, M.
Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be removed to get clean water. Hydroxyapatite (HAP) was synthesized from eggshells using the wet precipitation process. 'e as-synthesized HAP was characterized using Fourier Transform Infrared (FTIR) and X-ray powder diffraction (XRD). 'e synthesized HAP was mixed with three different clays: halloysite (HNT), kaolinite (KAO), and bentonite (BENT). 'e removal efficiency values of methylene blue (MB) from the data showed that HAP-BENT adsorbents had higher values, followed by HAP-HNT and then HAP-KAO adsorbents. 'e combined masses of 24 mg, 34.5 mg, and 33 mg (representing 20%, 15%, and 10% of HAP-BENT mass) had average adsorption capacity values of 20.7 mg/g, 17.2 mg/g, and 17.9 mg/g, respectively. For each mass percentage, the adsorption capacity values were found to decrease with adsorbent dosage. 'e HAP-BENT composites had removal efficiency values of 98.4, 91.9%, and 91.9%, respectively. Adsorption data for the HAP-BENT adsorbents were found to be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. 'e effect of temperature on adsorption capacity was evaluated and thermodynamical modeling was undertaken. 'e thermodynamical modeling predicts that based on the value of the change in enthalpy and Gibbs free energy the process was exothermic and spontaneous. 'is work confirms the potential of HAP-clay composites in removing MB from water.
Synthesis and Characterization of Modified Kaolin-Bentonite Composites for Enhanced Fluoride Removal from Drinking Water
(Hindawi, 2021) Annan, E.; Nyankson, E.; Agyei-Tuffour, B.; Armah, S.K.; Nkrumah-Buandoh, G.; Hodasi, J.A.M.; Oteng-Peprah, M.
Fluoride-contaminated drinking waters are known to cause severe health hazards such as fluorosis and arthritis. This paper presents the encapsulation of iron oxide nanoparticles in kaolin-bentonite composites adsorbents (KBNPs) for the removal of fluoride from drinking water by adsorption compared with kaolin-bentonite composite (KB). Adsorbents with an average weight of ∼200 mg and ∼7 mm diameter (granules) were prepared in the ratio of 10 :10 : 0.1 for kaolinite, bentonite, and magnetite nanoparticles, respectively. The granules were air-dried and calcined at 750°C and contacted with 2 mg/L sodium fluoride solution at varying time periods. .e adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) formulation, and Brunauer–Emmett–Teller (BET), whereas the adsorption mechanism and the kinetics were explained using the Langmuir isotherm, Freundlich models, and pseudo-first-order and pseudo-second-order models. The results showed that the BET surface areas for the granules were 10 m2 /g and 3 m2 /g for KBNPs and KB, respectively. The SEM images for the adsorbents before and after adsorption confirm the plate-like morphology of kaolin and bentonite. The FTIR analyses of bentonite (3550 cm−1 –4000 cm−1 ) and kaolin (400–1200 cm−1 ) correspond to the structural hydroxyl groups and water molecules in the interlayer space of bentonites and the vibrational modes of SiO4 tetrahedron of kaolin, respectively. The KBNPs composites also recorded a fluoride removal efficiency of ∼91% after 120 minutes compared with 64% for KB composites without Fe3O4 nanoparticles. .e adsorptions of fluoride by the KBNPs and KB granules were found to agree with the Freundlich isotherm and a pseudo-second-order kinetic model, respectively. .e results clearly show that the impregnation of clays with magnetite nanoparticles has significant effect in the removal of fluoride, and the implication of the results has been discussed to show the impact of clay-magnetite nanoparticles composites in the removal of fluoride from contaminated water.
Synthesis and characterization of zinc and copper oxide nanoparticles and their antibacteria activity
(Results in Materials, 2020) Asamoah, R.B.; Yaya, A.; Mensah, B.; Nbalayim, P.; Apalangya, V.; Bensah, Y.D.; Damoah, L.N.W.; Agyei-Tuffour, B.; Dodoo-Arhin, D.; Annan, E.
Inorganic nano-metal oxides can be effective alternatives to drug resistant organic antibiotics due to their broad spectrum antimicrobial activity against pathogenic and mutagenic gram-negative and positive bacteria. In this study, zinc and copper oxides (ZnO and CuO) were synthesised using a wet chemical reduction method. The oxide nanoparticles were characterized using X-ray diffraction (XRD), UV–Vis spectrometer, Fourier Transformed Infrared spectrometer and Transmission electron microscopy (TEM). The antibacterial activities of the nanoparticles were investigated against e. coli and s. aureus using disk diffusion and microdilution tests. The TEM micrographs showed that copper oxide nanoparticles assumed a nanorod shape of average length of 100 nm whiles zinc oxide nanoparticles were spherical of average diameter of 15 nm. The FTIR results showed that the nanoparticles were free of impurities and organic surfactants, which was confirmed by XRD. For the antibacteria tests, the minimum inhibition concentration (MIC) of CuO against e. coli and s. aureus were 1 mg/ml and 0.25 mg/ml respectively whiles it was 0.1 mg/ml for ZnO against s. aureus with ZnO producing no inhibition against e. coli. With the microdilution test, both nanoparticles exhibited activity against both bacterias at all varying concentrations. The results concluded that CuO had higher antibacteria activity compared to ZnO.
Ultra-short laser pulse interaction with nickel films
(ARPN Journal of Engineering and Applied Sciences, 2011-03) Annan, E.; Snelling, H.V.
Laser induced forward transfer method involves three sequence of events (i) laser pulse heats up the front surface of the film until it melts (ii) the melt front propagates through the film until it reaches the back surface and finally (iii) at or close to melt-through the metal vapour pressure at the front propels the molten film to the substrate. Many authors have shown potentials of this method in direct writing and photo-mask repair. In this paper, laser induced forward technique is applied to nickel films of thicknesses 98nm, 200nm and 322nm by using Ti: Sapphire femtosecond laser. Threshold energies for both direct and backside ablations are calculated. The feasibility of the transfer process is also demonstrated on nickel film on silicon wafer. Elevated features observed on some films during transfer process have been explained. © 2006-2011 Asian Research Publishing Network (ARPN).