This study investigates the fabrication, thermal conductivity and rheological characteristics eva... more This study investigates the fabrication, thermal conductivity and rheological characteristics evaluation of nanofluids consisting of copper nanoparticles in diethylene glycol base liquid. The fabri ...
A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engi... more A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engineered nanoparticles (ENPs) in biodegradable vegetable-based fluids, has been developed for integration into material processing technologies. This new product exhibits tribological properties superior to those of conventional metalworking fluids. The major innovation is the ability to create a stable nCLF through the modification of ENP surfaces. Functionalized MoS2 nanotube ENPs were successful used as low friction additives. The experimental work, required for the proof-of-concept and technology validation, was carried out on three different levels to quantify the improved tribological behavior of nCLF. These experiments include standard tribological tests, mock-up tests to simulate machining, and actual machining tests. It is demonstrated that the specific properties of ENPs, fluid design and composition, as well as specific lubrication mechanisms, exhibit superior performance of nCLF in terms of friction and wear. The objective of this paper is to demonstrate how recent nanotechnology developments support innovation needed for transitioning to sustainable production via new product development and integrated industrial applications.
Stability of nanofluids is one of the critical assessments for the efficient systems that the sol... more Stability of nanofluids is one of the critical assessments for the efficient systems that the solid content of nanofluid should be stable and well dispersed for longer time. Production of a homogen ...
Advanced substrate engineering is gaining new applications for nano-scaled devices where such sub... more Advanced substrate engineering is gaining new applications for nano-scaled devices where such substrates offer unique possibility to tailor the strain and the carrier transport. In general, XOI is a notation for wafers with a semiconductor-on-insulator where X is any alloy from SiGeSnC materials or III-V compounds. In special, strained XOI substrates (s-XOI) are widely used to manufacture nanowire transistors where the carrier mobility is enhanced by strain. So far, wafer bonding or condensation methods have been applied to manufacture XOI wafers. In case of SiGe-on-insulator (SGOI), a thin SiGe layer is grown on SOI and subsequently oxidized to create a single SiGe layer on oxide. During oxidation the Si atoms are preferably consumed and Ge atoms are driven toward the oxide box acting as a diffusion barrier. Therefore SGOI wafers suffer from point defects which have a strong influence on the carrier mobility, thermal conductivity and even optical properties. Post annealing may improve the layer quality and majority of the defects could be disappeared. The wafer bonding is more complicated and sensitive method. This relates to the requirements e.g. surface flatness, layer quality of the semiconductor and the amount of exerting bonding force. In manufacturing of Ge-on-insulator wafers, a high quality Ge layer is grown at 700-750 °C on a low quality Ge (grown at 300-400 °C). The Ge layers are transferred and bonded to oxide wafers by using a uniform force of few kNs. Afterwards, the wafers are annealed at 500-600 °C before etch back step (see Fig.1). It is important to mention here that the annealing step has to be decreased for bonding of GeSn-on-insulator wafers in order to avoid strain relaxation. In this work, manufacturing methods for different sizes of XOI and s-XOI wafers are presented and an attention is paid for using the manufactured XOI wafers for the thermoelectric application, where lateral nanowires are formed. As an example, for SiGe nanowires the seebeck coefficient is enhanced in presence of defects, however, any kind of defects in XOI wafers degrade the channel mobility in the processed MOSFETs. Characterization techniques e.g. high-resolution reciprocal maps using synchrotron x-ray beam, high resolution transmission electron microscopy, and photoluminescence were applied to detect the defects and estimate the strain relaxation. The experimental data is linked to explain the electrical properties of XOI wafers and finally to nanowires and MOSFETs. Figure 1
An effective, eco-friendly and easily scalable nanosilver-based technology offers affordable and ... more An effective, eco-friendly and easily scalable nanosilver-based technology offers affordable and broad-spectrum antimicrobial solutions against SARS-CoV-2 and Escherichia coli.
Bioconversion of organic materials is the foundation of many applications in chemical engineering... more Bioconversion of organic materials is the foundation of many applications in chemical engineering, microbiology and biochemistry. Herein, we introduce a new methodology to quantitatively determine conversion of biomass in viral infections while simultaneously imaging morphological changes of the host cell. As proof of concept, the viral replication of an unidentified giant DNA virus and the cellular response of an amoebal host are studied using soft X-ray microscopy, titration dilution measurements and thermal gravimetric analysis. We find that virions produced inside the cell are visible from 18 h post infection and their numbers increase gradually to a burst size of 280–660 virions. Due to the large size of the virion and its strong X-ray absorption contrast, we estimate that the burst size corresponds to a conversion of 6–12% of carbonaceous biomass from amoebal host to virus. The occurrence of virion production correlates with the appearance of a possible viral factory and morph...
This study investigates the fabrication, thermal conductivity and rheological characteristics eva... more This study investigates the fabrication, thermal conductivity and rheological characteristics evaluation of nanofluids consisting of copper nanoparticles in diethylene glycol base liquid. The fabri ...
A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engi... more A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engineered nanoparticles (ENPs) in biodegradable vegetable-based fluids, has been developed for integration into material processing technologies. This new product exhibits tribological properties superior to those of conventional metalworking fluids. The major innovation is the ability to create a stable nCLF through the modification of ENP surfaces. Functionalized MoS2 nanotube ENPs were successful used as low friction additives. The experimental work, required for the proof-of-concept and technology validation, was carried out on three different levels to quantify the improved tribological behavior of nCLF. These experiments include standard tribological tests, mock-up tests to simulate machining, and actual machining tests. It is demonstrated that the specific properties of ENPs, fluid design and composition, as well as specific lubrication mechanisms, exhibit superior performance of nCLF in terms of friction and wear. The objective of this paper is to demonstrate how recent nanotechnology developments support innovation needed for transitioning to sustainable production via new product development and integrated industrial applications.
Stability of nanofluids is one of the critical assessments for the efficient systems that the sol... more Stability of nanofluids is one of the critical assessments for the efficient systems that the solid content of nanofluid should be stable and well dispersed for longer time. Production of a homogen ...
Advanced substrate engineering is gaining new applications for nano-scaled devices where such sub... more Advanced substrate engineering is gaining new applications for nano-scaled devices where such substrates offer unique possibility to tailor the strain and the carrier transport. In general, XOI is a notation for wafers with a semiconductor-on-insulator where X is any alloy from SiGeSnC materials or III-V compounds. In special, strained XOI substrates (s-XOI) are widely used to manufacture nanowire transistors where the carrier mobility is enhanced by strain. So far, wafer bonding or condensation methods have been applied to manufacture XOI wafers. In case of SiGe-on-insulator (SGOI), a thin SiGe layer is grown on SOI and subsequently oxidized to create a single SiGe layer on oxide. During oxidation the Si atoms are preferably consumed and Ge atoms are driven toward the oxide box acting as a diffusion barrier. Therefore SGOI wafers suffer from point defects which have a strong influence on the carrier mobility, thermal conductivity and even optical properties. Post annealing may improve the layer quality and majority of the defects could be disappeared. The wafer bonding is more complicated and sensitive method. This relates to the requirements e.g. surface flatness, layer quality of the semiconductor and the amount of exerting bonding force. In manufacturing of Ge-on-insulator wafers, a high quality Ge layer is grown at 700-750 °C on a low quality Ge (grown at 300-400 °C). The Ge layers are transferred and bonded to oxide wafers by using a uniform force of few kNs. Afterwards, the wafers are annealed at 500-600 °C before etch back step (see Fig.1). It is important to mention here that the annealing step has to be decreased for bonding of GeSn-on-insulator wafers in order to avoid strain relaxation. In this work, manufacturing methods for different sizes of XOI and s-XOI wafers are presented and an attention is paid for using the manufactured XOI wafers for the thermoelectric application, where lateral nanowires are formed. As an example, for SiGe nanowires the seebeck coefficient is enhanced in presence of defects, however, any kind of defects in XOI wafers degrade the channel mobility in the processed MOSFETs. Characterization techniques e.g. high-resolution reciprocal maps using synchrotron x-ray beam, high resolution transmission electron microscopy, and photoluminescence were applied to detect the defects and estimate the strain relaxation. The experimental data is linked to explain the electrical properties of XOI wafers and finally to nanowires and MOSFETs. Figure 1
An effective, eco-friendly and easily scalable nanosilver-based technology offers affordable and ... more An effective, eco-friendly and easily scalable nanosilver-based technology offers affordable and broad-spectrum antimicrobial solutions against SARS-CoV-2 and Escherichia coli.
Bioconversion of organic materials is the foundation of many applications in chemical engineering... more Bioconversion of organic materials is the foundation of many applications in chemical engineering, microbiology and biochemistry. Herein, we introduce a new methodology to quantitatively determine conversion of biomass in viral infections while simultaneously imaging morphological changes of the host cell. As proof of concept, the viral replication of an unidentified giant DNA virus and the cellular response of an amoebal host are studied using soft X-ray microscopy, titration dilution measurements and thermal gravimetric analysis. We find that virions produced inside the cell are visible from 18 h post infection and their numbers increase gradually to a burst size of 280–660 virions. Due to the large size of the virion and its strong X-ray absorption contrast, we estimate that the burst size corresponds to a conversion of 6–12% of carbonaceous biomass from amoebal host to virus. The occurrence of virion production correlates with the appearance of a possible viral factory and morph...
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Papers by Muhammet S Toprak