In contrast to austenitic and martensitic stainless steels, ferritic stainless steels have a lowe... more In contrast to austenitic and martensitic stainless steels, ferritic stainless steels have a lower hardness and wear resistance but exhibit excellent corrosion resistance. Due to this fact, their use in the aerospace, automobile, and house construction industries is restricted. Several methods have been utilized to enhance the tribological characteristics of ferritic stainless steels. In this work, titanium nitride coating has been carried out by using a cathodic cage of titanium material, and later on, the titanium cathodic cage is replaced by an AISI-304 cathodic cage in a CCPN chamber to form iron nitride coating on AISI-430 ferritic stainless steel coupons through a plasma nitriding process for 4 h at a fixed temperature of 400 °C. The microstructures and mechanical traits of all processed and control coupons were analyzed using scanning electron microscopy, X-ray diffraction, ball-on-disc wear tester, and microhardness tester techniques. The results showed that hardness increas...
Novel composite comprising of Kulkual fibers and Titanium diboride (TiB2) filler reinforced epoxy... more Novel composite comprising of Kulkual fibers and Titanium diboride (TiB2) filler reinforced epoxy composites is investigated in the current work. Kulkual also known as Opuntia ficus‐indica is a plant abundantly found throughout Ethiopia are utilized in the form fibers in combination with TiB2 as reinforcement to synthesize epoxy matrix composites. Six types of composites including neat epoxy are fabricated using varying content of Kulkual fibers (0, 2.5, 5, 7.5, and 10 vol%) and fixed TiB2 content of 5 vol%. The fibers were obtained by drying the leaf‐like stem of Kulkual and collecting the skeleton structure found in cladodes. Alkaline treatment of Kulkual fiber to study its physical properties was also investigated. All composites' tensile moduli rise with increasing fiber content and are between 21% and 162% higher than the pure epoxy. All the composites tensile strength increase in the range from 43% to 211% compared to neat epoxy with EK‐10 composite revealing the greatest improvement. Flexural properties of all the composites increase with increase in Kulkual fiber content in comparison with neat epoxy. Good bonding of constituents and alkaline treatment of fibers results in enhanced properties of composites. Finally, fractured surfaces are analyzed with scanning electron micrographs to recognize structure property correspondences.
Methods for testing the presence of a virus in the blood are of interest to researchers and docto... more Methods for testing the presence of a virus in the blood are of interest to researchers and doctors because they determine how rapidly a virus is detected. In general, virus detection is a major scientific problem due to the serious effects of viruses on the human body. At present, only one virus can be detected in a single test. This potentially costs the medical establishment more time and money that could be saved if blood testing was more efficient. This study presents a qualitative method to enable doctors and researchers to detect more than one virus simultaneously. This was performed using quartz nanoparticles. Using polymer thin films of polydimethylsiloxane (PDMS), each chip emits a different frequency for each specific type of virus on the chip. The multiplicity of these chips allows for the detection of a number of viruses with the same number of nanoscale chips simultaneously. Blood flow around quartz nanoparticles was modelled. In this model, several conventional Quartz Crystal Microbalance (QCM) with nanostructures (Nano-QCM) particles are inserted into the three main types of blood vessels. The results showed that the best location for the Nano-QCM is the large artery and that it is possible to test for a number of viruses in all types of blood vessels.
Arrhythmia is a dangerous disease in which the heart rhythm varies and it may be very fast or ver... more Arrhythmia is a dangerous disease in which the heart rhythm varies and it may be very fast or very slow. Rapid heartbeats can lead to shortness of breath, chest pain, and sudden weakness, whereas slow heartbeats can lead to dizziness, problems with concentration, and constant stress. Finding an effective treatment for arrhythmia has become a very important endeavor for researchers and clinicians. In this article, we review the latest methodologies used in arrhythmia diagnosis and treatment. They include the application of five different types of artificial neural networks trained by machine learning and powered by artificial intelligence: convolutional, recurrent, feedforward, radial basis function, and modular neural network. Some of these methodologies are merged to enhance accuracy and efficacy. This review suggests that more research needs to be carried out in merging neural network types for their application in electrocardiogram (ECG).
Intravenous delivery is the fastest conventional method of delivering drugs to their targets in s... more Intravenous delivery is the fastest conventional method of delivering drugs to their targets in seconds, whereas intramuscular and subcutaneous injections provide a slower continuous delivery of drugs. In recent years, nanoparticle-based drug-delivery systems have gained considerable attention. During the progression of nanoparticles into the blood, the sound waves generated by the particles create acoustic pressure that affects the movement of nanoparticles. To overcome this issue, the impact of sound pressure levels on the development of nanoparticles was studied herein. In addition, a composite nanostructure was developed using different types of nanoscale substances to overcome the effect of sound pressure levels in the drug-delivery process. The results demonstrate the efficacy of the proposed nanostructure based on a group of different nanoparticles. This study suggests five materials, namely, polyimide, acrylic plastic, Aluminum 3003-H18, Magnesium AZ31B, and polysilicon for the design of the proposed structure. The best results were obtained in the case of the movement of these molecules at lower frequencies. The performance of acrylic plastic is better than other materials; the sound pressure levels reached minimum values at frequencies of 1, 10, 20, and 60 nHz. Furthermore, an experimental setup was designed to validate the proposed idea using advanced biomedical imaging technologies. The experimental results demonstrate the possibilities of detecting, tracking, and evaluating the movement behaviors of nanoparticles. The experimental results also demonstrate that the lowest sound pressure levels were observed at lower frequency levels, thus proving the validity of the proposed computational model assumptions. The outcome of this study will pave the way to understand the interaction behaviors of nanoparticles with the surrounding biological environments, including the sound pressure effect, which could lead to the useof such an effect in facilitating directional and tactic movements of the micro-and nano-motors.
Both micro electro mechanical systems (MEMS) based and lab-on-a chip (LoC) devices demand efficie... more Both micro electro mechanical systems (MEMS) based and lab-on-a chip (LoC) devices demand efficient micro-scale mixing mechanisms for its effective control which necessitates the quality research towards more efficient designs. A new venture is investigated in those direction with mixing micro-channel constricted with rectangular block under pressure-driven electro-osmotic flow and is numerically simulated by a modified immersed boundary method (IBM), an alternative technique in computational fluid dynamics (CFD). The electro-osmotic flow elucidated by electrical double layer theory when simultaneously considered with pressure driven flow in micro channels can be effectively figured out by the solution of Navier-Stokes equations linked with Nernst-Planck and Poisson equations for transportation of ion and electric field respectively. In this study, the effect of varying the height of rectangular block on the flow and mixing performance are analyzed. A hybrid method, which is a combination of active and passive techniques, is introduced simultaneously in the microchannel by the electro-osmotic effects and channel constriction. The approach is on the basis of finite volume methodology on a staggered mesh. The governing equations are solved by a time-integration technique based on a fractional step method. The velocity fields are corrected by a pseudo-pressure term to ensure the continuity in each computational time step. The extent of mixing in every cross section of the micro channel is assessed by a suitable mixing efficiency parameter. This study has shed light on the most predominant factors that influence mixing efficiency in a micro-channel, such as geometry of the block, non-dimensional numbers (Reynolds number, Re and Peclet number, Pe), zeta potential, external electric field strength and electrical double layer (EDL) thickness. The maximum efficiency in this micro mixer design is found to be 51.3% for Reynolds number of 0.05 and Peclet number of 450 with the rectangular block height of 0.75. It is clear that both electro osmotic effects and flow perturbations due to channel constriction caused a remarkable improvement in mixing efficiency. The outcomes of this investigation are widely applicable in cooling of microchips, heat sinks of MEMS based devices, drug delivery applications and Deoxyribonucleic acid (DNA) hybridization. The present IBM model is validated by experimental and numerical results from the literature.
Arsenic (As 3+) is the most carcinogenic and abundantly available heavy metal present in the envi... more Arsenic (As 3+) is the most carcinogenic and abundantly available heavy metal present in the environment. Vertically aligned ZnO nanorod (ZnO-NR) growth was achieved on metallic nickel foam substrate via a wet chemical route and it was used as an electrochemical sensor towards As(III) detection in polluted water. Crystal structure confirmation, surface morphology observation and elemental analysis of ZnO-NRs were conducted using X-ray diffraction, field-emission scanning electron microscopy and energydispersive X-ray spectroscopy, respectively. Electrochemical sensing performance of ZnO-NRs@Ni-foam electrode/substrate was investigated via linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in a carbonate buffer solution of pH = 9 and at different As(III) molar concentrations in solution. Under optimum conditions, the anodic peak current was found proportional to the arsenite concentration from 0.1 mM to 1.0 mM. The achieved values for limit of detection and limit of quantification were 0.046 ppm and 0.14 ppm, respectively, which are far lower than the recommended limits for As(III) detection in drinking water as suggested by the World Health Organization. This suggests that ZnO-NRs@Ni-foam electrode/substrate can be effectively utilized in terms of its electrocatalytic activity towards As 3+ detection in drinking water.
Journal of materials research and technology, May 1, 2019
This paper embodies the findings of a study on improving the surface tribology of Al alloy 6082-T... more This paper embodies the findings of a study on improving the surface tribology of Al alloy 6082-T6 through plasma electrolytic oxidation (PEO) process. The surface macro/microstructure and composition were investigated. Electrochemical measurements were performed at temperatures of 20 and 80 • C using an inductively coupled plasma and open circuit potential tests after immersion in 3.5%NaCl solution. The erosion tests were performed with water carrying sand particles at different sand loadings (200 and 1000 mg/l) and temperatures (20 and 80 • C). After erosion experiments, the weight loss measurements were recorded, and the worn surfaces were assessed through SEM study and profilometry analysis. The micro-hardness of the coated layer and the substrate were measured before and after the erosion test. The formed PEO layer of 40 m thick was almost sound, uniform, well adhered to the substrate and consisted mainly of alumina phases (␣-Al 2 O 3 , ␥-Al 2 O 3). The relative proportions of ␣-Al 2 O 3 to ␥-Al 2 O 3 were 31: 79%. The PEO coating shows much better corrosion and erosion resistance and less surface damage compared to the aluminum substrate, especially at elevated temperature and high sand loading. The PEO hardness increases as the distance from the substrate increases until near the middle of the coating.
This study communicates the theoretical investigations on the cubic double perovskite compounds C... more This study communicates the theoretical investigations on the cubic double perovskite compounds Cs 2 XCrCl 6 (X = K or Na). Density functional theory (DFT) calculations were carried out using the TB-mBJ approximation. These compounds were found to be stable in the cubic perovskite structure having lattice constants in the range of 10.58-10.20. The stability of the investigated materials was assessed by the Gold-Schmidt tolerance method, which resulted in the tolerance factor values of 0.891 and 0.951 for Cs 2 KCrCl 6 and Cs 2 NaCrCl 6 , respectively. The calculated values of the elastic constants C 11 , C 12 , and C 44 of the cubic compounds studied by our research team confirm the elastic stability. The values of the formation energies were also calculated for both the compounds and were found in the range from −2.1 to −2.3. The electronic behavior of the presently investigated materials was examined by inspecting their band structures and the density of states. It was observed that both the materials have half-metallic nature. To check the suitability of the studied compounds in optical applications, we determined the real and imaginary parts of their respective dielectric functions, absorption coefficients, optical conductivities, refractive index, and reflectivity as a function of a wide range of incident photon energies up to 40 eV.
In contrast to austenitic and martensitic stainless steels, ferritic stainless steels have a lowe... more In contrast to austenitic and martensitic stainless steels, ferritic stainless steels have a lower hardness and wear resistance but exhibit excellent corrosion resistance. Due to this fact, their use in the aerospace, automobile, and house construction industries is restricted. Several methods have been utilized to enhance the tribological characteristics of ferritic stainless steels. In this work, titanium nitride coating has been carried out by using a cathodic cage of titanium material, and later on, the titanium cathodic cage is replaced by an AISI-304 cathodic cage in a CCPN chamber to form iron nitride coating on AISI-430 ferritic stainless steel coupons through a plasma nitriding process for 4 h at a fixed temperature of 400 °C. The microstructures and mechanical traits of all processed and control coupons were analyzed using scanning electron microscopy, X-ray diffraction, ball-on-disc wear tester, and microhardness tester techniques. The results showed that hardness increas...
Novel composite comprising of Kulkual fibers and Titanium diboride (TiB2) filler reinforced epoxy... more Novel composite comprising of Kulkual fibers and Titanium diboride (TiB2) filler reinforced epoxy composites is investigated in the current work. Kulkual also known as Opuntia ficus‐indica is a plant abundantly found throughout Ethiopia are utilized in the form fibers in combination with TiB2 as reinforcement to synthesize epoxy matrix composites. Six types of composites including neat epoxy are fabricated using varying content of Kulkual fibers (0, 2.5, 5, 7.5, and 10 vol%) and fixed TiB2 content of 5 vol%. The fibers were obtained by drying the leaf‐like stem of Kulkual and collecting the skeleton structure found in cladodes. Alkaline treatment of Kulkual fiber to study its physical properties was also investigated. All composites' tensile moduli rise with increasing fiber content and are between 21% and 162% higher than the pure epoxy. All the composites tensile strength increase in the range from 43% to 211% compared to neat epoxy with EK‐10 composite revealing the greatest improvement. Flexural properties of all the composites increase with increase in Kulkual fiber content in comparison with neat epoxy. Good bonding of constituents and alkaline treatment of fibers results in enhanced properties of composites. Finally, fractured surfaces are analyzed with scanning electron micrographs to recognize structure property correspondences.
Methods for testing the presence of a virus in the blood are of interest to researchers and docto... more Methods for testing the presence of a virus in the blood are of interest to researchers and doctors because they determine how rapidly a virus is detected. In general, virus detection is a major scientific problem due to the serious effects of viruses on the human body. At present, only one virus can be detected in a single test. This potentially costs the medical establishment more time and money that could be saved if blood testing was more efficient. This study presents a qualitative method to enable doctors and researchers to detect more than one virus simultaneously. This was performed using quartz nanoparticles. Using polymer thin films of polydimethylsiloxane (PDMS), each chip emits a different frequency for each specific type of virus on the chip. The multiplicity of these chips allows for the detection of a number of viruses with the same number of nanoscale chips simultaneously. Blood flow around quartz nanoparticles was modelled. In this model, several conventional Quartz Crystal Microbalance (QCM) with nanostructures (Nano-QCM) particles are inserted into the three main types of blood vessels. The results showed that the best location for the Nano-QCM is the large artery and that it is possible to test for a number of viruses in all types of blood vessels.
Arrhythmia is a dangerous disease in which the heart rhythm varies and it may be very fast or ver... more Arrhythmia is a dangerous disease in which the heart rhythm varies and it may be very fast or very slow. Rapid heartbeats can lead to shortness of breath, chest pain, and sudden weakness, whereas slow heartbeats can lead to dizziness, problems with concentration, and constant stress. Finding an effective treatment for arrhythmia has become a very important endeavor for researchers and clinicians. In this article, we review the latest methodologies used in arrhythmia diagnosis and treatment. They include the application of five different types of artificial neural networks trained by machine learning and powered by artificial intelligence: convolutional, recurrent, feedforward, radial basis function, and modular neural network. Some of these methodologies are merged to enhance accuracy and efficacy. This review suggests that more research needs to be carried out in merging neural network types for their application in electrocardiogram (ECG).
Intravenous delivery is the fastest conventional method of delivering drugs to their targets in s... more Intravenous delivery is the fastest conventional method of delivering drugs to their targets in seconds, whereas intramuscular and subcutaneous injections provide a slower continuous delivery of drugs. In recent years, nanoparticle-based drug-delivery systems have gained considerable attention. During the progression of nanoparticles into the blood, the sound waves generated by the particles create acoustic pressure that affects the movement of nanoparticles. To overcome this issue, the impact of sound pressure levels on the development of nanoparticles was studied herein. In addition, a composite nanostructure was developed using different types of nanoscale substances to overcome the effect of sound pressure levels in the drug-delivery process. The results demonstrate the efficacy of the proposed nanostructure based on a group of different nanoparticles. This study suggests five materials, namely, polyimide, acrylic plastic, Aluminum 3003-H18, Magnesium AZ31B, and polysilicon for the design of the proposed structure. The best results were obtained in the case of the movement of these molecules at lower frequencies. The performance of acrylic plastic is better than other materials; the sound pressure levels reached minimum values at frequencies of 1, 10, 20, and 60 nHz. Furthermore, an experimental setup was designed to validate the proposed idea using advanced biomedical imaging technologies. The experimental results demonstrate the possibilities of detecting, tracking, and evaluating the movement behaviors of nanoparticles. The experimental results also demonstrate that the lowest sound pressure levels were observed at lower frequency levels, thus proving the validity of the proposed computational model assumptions. The outcome of this study will pave the way to understand the interaction behaviors of nanoparticles with the surrounding biological environments, including the sound pressure effect, which could lead to the useof such an effect in facilitating directional and tactic movements of the micro-and nano-motors.
Both micro electro mechanical systems (MEMS) based and lab-on-a chip (LoC) devices demand efficie... more Both micro electro mechanical systems (MEMS) based and lab-on-a chip (LoC) devices demand efficient micro-scale mixing mechanisms for its effective control which necessitates the quality research towards more efficient designs. A new venture is investigated in those direction with mixing micro-channel constricted with rectangular block under pressure-driven electro-osmotic flow and is numerically simulated by a modified immersed boundary method (IBM), an alternative technique in computational fluid dynamics (CFD). The electro-osmotic flow elucidated by electrical double layer theory when simultaneously considered with pressure driven flow in micro channels can be effectively figured out by the solution of Navier-Stokes equations linked with Nernst-Planck and Poisson equations for transportation of ion and electric field respectively. In this study, the effect of varying the height of rectangular block on the flow and mixing performance are analyzed. A hybrid method, which is a combination of active and passive techniques, is introduced simultaneously in the microchannel by the electro-osmotic effects and channel constriction. The approach is on the basis of finite volume methodology on a staggered mesh. The governing equations are solved by a time-integration technique based on a fractional step method. The velocity fields are corrected by a pseudo-pressure term to ensure the continuity in each computational time step. The extent of mixing in every cross section of the micro channel is assessed by a suitable mixing efficiency parameter. This study has shed light on the most predominant factors that influence mixing efficiency in a micro-channel, such as geometry of the block, non-dimensional numbers (Reynolds number, Re and Peclet number, Pe), zeta potential, external electric field strength and electrical double layer (EDL) thickness. The maximum efficiency in this micro mixer design is found to be 51.3% for Reynolds number of 0.05 and Peclet number of 450 with the rectangular block height of 0.75. It is clear that both electro osmotic effects and flow perturbations due to channel constriction caused a remarkable improvement in mixing efficiency. The outcomes of this investigation are widely applicable in cooling of microchips, heat sinks of MEMS based devices, drug delivery applications and Deoxyribonucleic acid (DNA) hybridization. The present IBM model is validated by experimental and numerical results from the literature.
Arsenic (As 3+) is the most carcinogenic and abundantly available heavy metal present in the envi... more Arsenic (As 3+) is the most carcinogenic and abundantly available heavy metal present in the environment. Vertically aligned ZnO nanorod (ZnO-NR) growth was achieved on metallic nickel foam substrate via a wet chemical route and it was used as an electrochemical sensor towards As(III) detection in polluted water. Crystal structure confirmation, surface morphology observation and elemental analysis of ZnO-NRs were conducted using X-ray diffraction, field-emission scanning electron microscopy and energydispersive X-ray spectroscopy, respectively. Electrochemical sensing performance of ZnO-NRs@Ni-foam electrode/substrate was investigated via linear sweep voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy in a carbonate buffer solution of pH = 9 and at different As(III) molar concentrations in solution. Under optimum conditions, the anodic peak current was found proportional to the arsenite concentration from 0.1 mM to 1.0 mM. The achieved values for limit of detection and limit of quantification were 0.046 ppm and 0.14 ppm, respectively, which are far lower than the recommended limits for As(III) detection in drinking water as suggested by the World Health Organization. This suggests that ZnO-NRs@Ni-foam electrode/substrate can be effectively utilized in terms of its electrocatalytic activity towards As 3+ detection in drinking water.
Journal of materials research and technology, May 1, 2019
This paper embodies the findings of a study on improving the surface tribology of Al alloy 6082-T... more This paper embodies the findings of a study on improving the surface tribology of Al alloy 6082-T6 through plasma electrolytic oxidation (PEO) process. The surface macro/microstructure and composition were investigated. Electrochemical measurements were performed at temperatures of 20 and 80 • C using an inductively coupled plasma and open circuit potential tests after immersion in 3.5%NaCl solution. The erosion tests were performed with water carrying sand particles at different sand loadings (200 and 1000 mg/l) and temperatures (20 and 80 • C). After erosion experiments, the weight loss measurements were recorded, and the worn surfaces were assessed through SEM study and profilometry analysis. The micro-hardness of the coated layer and the substrate were measured before and after the erosion test. The formed PEO layer of 40 m thick was almost sound, uniform, well adhered to the substrate and consisted mainly of alumina phases (␣-Al 2 O 3 , ␥-Al 2 O 3). The relative proportions of ␣-Al 2 O 3 to ␥-Al 2 O 3 were 31: 79%. The PEO coating shows much better corrosion and erosion resistance and less surface damage compared to the aluminum substrate, especially at elevated temperature and high sand loading. The PEO hardness increases as the distance from the substrate increases until near the middle of the coating.
This study communicates the theoretical investigations on the cubic double perovskite compounds C... more This study communicates the theoretical investigations on the cubic double perovskite compounds Cs 2 XCrCl 6 (X = K or Na). Density functional theory (DFT) calculations were carried out using the TB-mBJ approximation. These compounds were found to be stable in the cubic perovskite structure having lattice constants in the range of 10.58-10.20. The stability of the investigated materials was assessed by the Gold-Schmidt tolerance method, which resulted in the tolerance factor values of 0.891 and 0.951 for Cs 2 KCrCl 6 and Cs 2 NaCrCl 6 , respectively. The calculated values of the elastic constants C 11 , C 12 , and C 44 of the cubic compounds studied by our research team confirm the elastic stability. The values of the formation energies were also calculated for both the compounds and were found in the range from −2.1 to −2.3. The electronic behavior of the presently investigated materials was examined by inspecting their band structures and the density of states. It was observed that both the materials have half-metallic nature. To check the suitability of the studied compounds in optical applications, we determined the real and imaginary parts of their respective dielectric functions, absorption coefficients, optical conductivities, refractive index, and reflectivity as a function of a wide range of incident photon energies up to 40 eV.
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Papers by Ali Algahtani