Microfluidic devices have been widely used in mechanical, biomedical, chemical, and materials res... more Microfluidic devices have been widely used in mechanical, biomedical, chemical, and materials research. As a result, it is becoming increasingly important to have a cheap, fast, and reliable method for rapid microfabrication. However, prototyping of microfluidic devices typically suffers from the high initial cost, low resolution, rough surface finish, and long turn-around time. Here we present a strategic approach to closed-loop control of deterministic fabrication process based on in-situ image analysis called image-guided in-situ maskless lithography (IGIs-ML). Using the closed-loop control along with flush-flow functionality and leveraging the swelling behavior of the photocurable polymer, we demonstrate the fabrication of sub-micron high aspect ratio channels (800 nm width and >10 µm height) close to the light diffraction limit. This outperforms any reported rapid prototyping platforms which can typically reach tens of µm in channel width. Such dimensional capability is even...
<jats:title>Abstract</jats:title> <jats:p>Germanene, a two-dimensional honeycom... more <jats:title>Abstract</jats:title> <jats:p>Germanene, a two-dimensional honeycomb structure consisting of germanium atoms, has been reported to possess excellent mechanical, optical, thermal and electronic properties. Recently, it has been revealed that covalent bonding between two germanene sheets leads to integration of intrinsic magnetism and spontaneous band gap opening that makes it attractive to future nanoelectronics as well as spin-based computation and data storage. In order to use the captivating features of germanene sheets coupled by covalent bonding, its mechanical characterization needs to be studied. In this study, molecular dynamics simulations have been performed using optimized tersoff potential to analyze the effect of chirality, temperature and strain rate on the uniaxial tensile properties of this structure. This study suggests that uniaxial loading in armchair direction shows higher strength and fracture strain compared to the zigzag direction. The results reveal that with the increasing temperature both the ultimate tensile strength and fracture strain of the structure get reduced. These reductions are more significant in case of armchair loading than zigzag loading. The nature of failure is more brittle in armchair loading. Furthermore, the UTS increases with increasing strain rate. These results are expected to provide significant insight to the investigation of this structure as a potential nanoelectronics substitute.</jats:p>
Intracellular drug delivery by rapid squeezing is one of the most recent and simple cell membrane... more Intracellular drug delivery by rapid squeezing is one of the most recent and simple cell membrane disruption-mediated drug encapsulation approaches. In this method, cell membranes are perforated in a microfluidic setup due to rapid cell deformation during squeezing through constricted channels. While squeezing-based drug loading has been successful in loading drug molecules into various cell types, such as immune cells, cancer cells, and other primary cells, there is so far no comprehensive understanding of the pore opening mechanism on the cell membrane and the systematic analysis on how different channel geometries and squeezing speed influence drug loading. This article aims to develop a three-dimensional computational model to study the intracellular delivery for compound cells squeezing through microfluidic channels. The Lattice Boltzmann method, as the flow solver, integrated with a spring-connected network via frictional coupling, is employed to capture compound capsule dynamics over fast squeezing. The pore size is proportional to the local areal strain of triangular patches on the compound cell through mathematical correlations derived from molecular dynamics and coarse-grained molecular dynamics simulations. We quantify the drug concentration inside the cell cytoplasm by introducing a new mathematical model for passive diffusion after squeezing. Compared to the existing models, the proposed model does not have any empirical parameters that depend on operating conditions and device geometry. Since the compound cell model is new, it is validated by simulating a nucleated cell under a simple shear flow at different capillary numbers and comparing the results with other numerical models reported in literature. The cell deformation during squeezing is also compared with the pattern found from our compound cell squeezing experiment. Afterward, compound cell squeezing is modeled for different cell squeezing velocities, constriction lengths, and constriction widths. We reported the instantaneous cell center velocity, variations of axial and vertical cell dimensions, cell porosity, and normalized drug concentration to shed light on the underlying physics in fast squeezing-based drug delivery. Consistent with experimental findings in the literature, the numerical results confirm that constriction width reduction, constriction length enlargement, and average cell velocity promote intracellular drug delivery. The results show that the existence of the nucleus increases cell porosity and loaded drug concentration after squeezing. Given geometrical parameters and cell average velocity, the maximum porosity is achieved at three different locations: constriction entrance, constriction middle part, and outside the constriction. Our numerical results provide reasonable justifications for experimental findings on the influences of constriction geometry and cell velocity on the performance of cell-squeezing delivery. We expect this model can help design and optimize squeezingbased cargo delivery.
TENCON 2017 - 2017 IEEE Region 10 Conference, 2017
Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these proper... more Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these properties on temperature, strain rate, and the inclusion of vacancy defects have been explored with molecular dynamics simulations using Tersoff potential. The ultimate tensile strength of pristine hexagonal boron nitride nanoribbon of 26 nm x 5 nm with armchair chirality is found to be 100.5 GPa. The ultimate tensile strength and strain have been found decreasing with increasing the temperature while an opposite trend has been observed for increasing the strain rate. Furthermore, the vacancy defects reduce ultimate tensile strength and strain where the effect of bi-vacancy is clearly dominating over point vacancy.
In this paper, we propose a multiscale numerical algorithm to simulate the hemolytic release of h... more In this paper, we propose a multiscale numerical algorithm to simulate the hemolytic release of hemoglobin (Hb) from red blood cells (RBCs) flowing through sieves containing micropores with mean diameters smaller than RBCs. Analyzing the RBC damage in microfiltration is important in the sense that it can quantify the sensitivity of human erythrocytes to mechanical hemolysis while they undergo high shear rate and high deformation. Here, the numerical simulations are carried out via lattice Boltzmann method and spring connected network (SN) coupled by an immersed boundary method. To predict the RBC sublytic damage, a sub-cellular damage model derived from molecular dynamic simulations is incorporated in the cellular solver. In the proposed algorithm, the local RBC strain distribution calculated by the cellular solver is used to obtain the pore radius on the RBC membrane. Index of hemolysis (IH) is calculated by resorting to the resulting pore radius and solving a diffusion equation considering the effects of steric hinderance and increased hydrodynamic drag due to the size of the hemoglobin molecule. It should be mentioned that current computational hemolysis models usually utilize empirical fitting of the released free hemoglobin (Hb) in plasma from damaged RBCs. These empirical correlations contain ad hoc parameters that depend on specific device and operating conditions, thus cannot be used to predict hemolysis under different conditions. In contrast to the available hemolysis model, the proposed algorithm does not have any empirical parameters. Therefore, it can predict the IH in microfilter with different sieve pore sizes and filtration pressures. Also, in contrast to empirical correlations in which the Hb release is related to shear stress and exposure time without considering the physical processes, the proposed model links flow-induced deformation of the RBC membrane to membrane permeabilization and hemoglobin release. In this paper, the cellular solver is validated by simulating optical tweezers experiment, shear flow experiment as well as an experiment to measure RBC deformability in a very narrow microchannel. Moreover, the shape of a single RBC at the rupture moment is compared with corresponding experimental data. Finally, to validate the damage model, the results obtained from our parametric study on the role of filtration pressure and sieve pore size in Hb release are compared with experimental data. Numerical results are in good agreement with experimental data. Similar to the corresponding experiment, the numerical results confirm that hemolysis increases with increasing the filtration pressure and reduction in pore size on the sieve. While in experiment, the RBC pore size cannot be measured, the numerical results Yaling Liu,
Comment on "Multiphoton induced photoluminescence during time-resolved laser-induced incandescenc... more Comment on "Multiphoton induced photoluminescence during time-resolved laser-induced incandescence experiments on silver and gold nanoparticles" [
Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), 2021
Solder joints, an integral part in electrical appliances, undergo steady or fluctuating strain th... more Solder joints, an integral part in electrical appliances, undergo steady or fluctuating strain throughout their lifetime for which the components develop cracks and the components become susceptible to failure. Uniaxial and cyclic loading have different outcomes of damage accumulation, eventually making the electrical components susceptible to failure. In this study, the effects of two parameters (temperature and solder-alloy composition) on the uniaxial and also, for the first time, on the cyclic stress-strain behavior of lead-free solders at nanoscale were observed. A rectangular-box model of SAC (alloy of Sn, Ag and Cu), a lead-free solder, was subjected to uniaxial and cyclic (tension and compression) loading at nanoscale. The effects of uniaxial loading on SAC alloys were also observed through the simulations and the failure criterion was also observed as to get a better view on the cracks. A negative correlation between temperature and UTS (Ultimate Tensile Strength) was observed. Also, the nanoscale model was cyclically loaded under strain-controlled conditions (constant positive and negative strain limits). The study aims at determining the hysteresis loop size (area), for a stable cycle, that was calculated for a given solder alloy and varying temperature. This area represents the strain energy density dissipated per cycle, which can be correlated to the damage accumulation in the joint. In this study, most simulations were performed with SAC305. However, simulations were also performed for four SAC alloys in total (105,205,305,405) with varying silver content (1-4%) under strain-controlled cyclic loading and uniaxial loading. In addition, the effect of the temperature has also been studied by performing simulations of cyclic loading of SACN05 (N=1,2,3,4) models at six different temperatures (300, 323, 348, 373, 398 and 423K). An increase in the plastic strain range and a drop of the peak stress and loop area were found at higher temperatures.
Transient pore formation on the membrane of red blood cells (RBCs) under high mechanical tensions... more Transient pore formation on the membrane of red blood cells (RBCs) under high mechanical tensions is of great importance in many biomedical applications, such as RBC damage (hemolysis) and mechanoporation-based drug delivery. The dynamic process of pore formation, growth, and resealing is hard to visualize in experiments. We developed a mesoscale coarse-grained model to study the characteristics of transient pores on a patch of the lipid bilayer that is strengthened by an elastic meshwork representing the cytoskeleton. Unsteady molecular dynamics was used to study the pore formation and reseal at high strain rates close to the physiological ranges. The critical strain for pore formation, pore characteristics, and cytoskeleton effects were studied. Results show that the presence of the cytoskeleton increases the critical strain of pore formation and confines the pore growth. Moreover, the pore recovery process under negative strain rates (compression) is analyzed. Simulations show that pores can remain open for a long time during the high-speed tank-treading induced stretching and compression process that a patch of the RBC membrane usually experiences under high shear flow. Furthermore, complex loading conditions can affect the pore characteristics and result in denser pores. Finally, the effects of strain rate on pore formation are analyzed. Higher rate stretching of membrane patch can result in a significant increase in the critical areal strain and density of pores. Such a model reveals the dynamic molecular process of RBC damage in biomedical devices and mechanoporation that, to our knowledge, has not been reported before.
The mechanical properties of Cadmium Selenide (CdSe) nanowire is an emerging issue due to its app... more The mechanical properties of Cadmium Selenide (CdSe) nanowire is an emerging issue due to its application in semiconductor and optoelectronics industries. In this paper, we conducted molecular dynamics (MD) simulations to investigate the temperature-dependent mechanical properties and failure behavior of Zinc-Blende (ZB) CdSe nanowire under uniaxial tensile deformation. We employed Stillinger-Weber (SW) potential to describe the inter-atomic interactions. The effect of variation of temperatures (100 K-600 K), sizes, and crystal orientation on the tensile response of the CdSe nanowires is investigated. Our simulation results suggest that both ultimate tensile strength and Young's modulus of CdSe have an inverse relationship with temperature. From 100K to 600K, the ZB CdSe exhibits brittle type failure thus there is no brittle to ductile transition temperature found. Results also suggest that size has a significant effect on the mechanical properties of CdSe nanowire. It has been found that as the cross-sectional area increases both ultimate tensile stress and Young's modulus increases as well. The [111] oriented ZB CdSe shows the largest ultimate tensile strength, Young's modulus and fracture toughness whereas the values are lowest for [100] orientation. The [110] orientation shows the largest failure strain compared to other orientations. Finally, failure mechanisms of CdSe nanowire are also investigated at 100K and 600K. We noticed that at 100K temperature [100] oriented ZB CdSe fails along {111} cleavage plane however in the case of 600 K temperature, both {111} and {100} planes are activated and cause fracture of CdSe nanowire at lower strain value. This study can guide to design ZB CdSe based solar cell, optoelectronic and semiconductor devices by presenting a comprehensive understanding of the mechanical and fracture characteristics of this nanowire.
Thermal transport in defected graphene/stanene hetero-bilayer nanostructures has been investigate... more Thermal transport in defected graphene/stanene hetero-bilayer nanostructures has been investigated to encourage the optimal design of thermal and nanoelectronic devices.
COVID-19 has challenged the world’s public health and led to over 4.5 million deaths. A rapid, se... more COVID-19 has challenged the world’s public health and led to over 4.5 million deaths. A rapid, sensitive, and cost-effective point-of-care virus detection device is crucial to the control and surveillance of the contagious severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. Here we demonstrate a solid phase isothermal recombinase polymerase amplification coupled CRISPR-based (spRPA-CRISPR) assay for on-chip multiplexed, sensitive and visual COVID-19 DNA detection. By targeting the SARS-CoV-2 structure protein encoded genomes, two specific genes were simultaneously detected with the control sample without cross-interaction with other sequences. The endpoint signal can be directly visualized for rapid detection of COVID-19. The amplified target sequences were immobilized on the one-pot device surface and detected using the mixed Cas12a-crRNA collateral cleavage of reporter released fluorescent signal when specific genes were recognized. The system was tested with sa...
The constant thickness in the microfluidic channel is used for controlled absorption of red and b... more The constant thickness in the microfluidic channel is used for controlled absorption of red and blue light to measure red blood cell hemoglobin and height mapping. High speed recording of the height mapping provides us the membrane fluctuation.
Microfluidic devices have been widely used in mechanical, biomedical, chemical, and materials res... more Microfluidic devices have been widely used in mechanical, biomedical, chemical, and materials research. As a result, it is becoming increasingly important to have a cheap, fast, and reliable method for rapid microfabrication. However, prototyping of microfluidic devices typically suffers from the high initial cost, low resolution, rough surface finish, and long turn-around time. Here we present a strategic approach to closed-loop control of deterministic fabrication process based on in-situ image analysis called image-guided in-situ maskless lithography (IGIs-ML). Using the closed-loop control along with flush-flow functionality and leveraging the swelling behavior of the photocurable polymer, we demonstrate the fabrication of sub-micron high aspect ratio channels (800 nm width and >10 µm height) close to the light diffraction limit. This outperforms any reported rapid prototyping platforms which can typically reach tens of µm in channel width. Such dimensional capability is even...
<jats:title>Abstract</jats:title> <jats:p>Germanene, a two-dimensional honeycom... more <jats:title>Abstract</jats:title> <jats:p>Germanene, a two-dimensional honeycomb structure consisting of germanium atoms, has been reported to possess excellent mechanical, optical, thermal and electronic properties. Recently, it has been revealed that covalent bonding between two germanene sheets leads to integration of intrinsic magnetism and spontaneous band gap opening that makes it attractive to future nanoelectronics as well as spin-based computation and data storage. In order to use the captivating features of germanene sheets coupled by covalent bonding, its mechanical characterization needs to be studied. In this study, molecular dynamics simulations have been performed using optimized tersoff potential to analyze the effect of chirality, temperature and strain rate on the uniaxial tensile properties of this structure. This study suggests that uniaxial loading in armchair direction shows higher strength and fracture strain compared to the zigzag direction. The results reveal that with the increasing temperature both the ultimate tensile strength and fracture strain of the structure get reduced. These reductions are more significant in case of armchair loading than zigzag loading. The nature of failure is more brittle in armchair loading. Furthermore, the UTS increases with increasing strain rate. These results are expected to provide significant insight to the investigation of this structure as a potential nanoelectronics substitute.</jats:p>
Intracellular drug delivery by rapid squeezing is one of the most recent and simple cell membrane... more Intracellular drug delivery by rapid squeezing is one of the most recent and simple cell membrane disruption-mediated drug encapsulation approaches. In this method, cell membranes are perforated in a microfluidic setup due to rapid cell deformation during squeezing through constricted channels. While squeezing-based drug loading has been successful in loading drug molecules into various cell types, such as immune cells, cancer cells, and other primary cells, there is so far no comprehensive understanding of the pore opening mechanism on the cell membrane and the systematic analysis on how different channel geometries and squeezing speed influence drug loading. This article aims to develop a three-dimensional computational model to study the intracellular delivery for compound cells squeezing through microfluidic channels. The Lattice Boltzmann method, as the flow solver, integrated with a spring-connected network via frictional coupling, is employed to capture compound capsule dynamics over fast squeezing. The pore size is proportional to the local areal strain of triangular patches on the compound cell through mathematical correlations derived from molecular dynamics and coarse-grained molecular dynamics simulations. We quantify the drug concentration inside the cell cytoplasm by introducing a new mathematical model for passive diffusion after squeezing. Compared to the existing models, the proposed model does not have any empirical parameters that depend on operating conditions and device geometry. Since the compound cell model is new, it is validated by simulating a nucleated cell under a simple shear flow at different capillary numbers and comparing the results with other numerical models reported in literature. The cell deformation during squeezing is also compared with the pattern found from our compound cell squeezing experiment. Afterward, compound cell squeezing is modeled for different cell squeezing velocities, constriction lengths, and constriction widths. We reported the instantaneous cell center velocity, variations of axial and vertical cell dimensions, cell porosity, and normalized drug concentration to shed light on the underlying physics in fast squeezing-based drug delivery. Consistent with experimental findings in the literature, the numerical results confirm that constriction width reduction, constriction length enlargement, and average cell velocity promote intracellular drug delivery. The results show that the existence of the nucleus increases cell porosity and loaded drug concentration after squeezing. Given geometrical parameters and cell average velocity, the maximum porosity is achieved at three different locations: constriction entrance, constriction middle part, and outside the constriction. Our numerical results provide reasonable justifications for experimental findings on the influences of constriction geometry and cell velocity on the performance of cell-squeezing delivery. We expect this model can help design and optimize squeezingbased cargo delivery.
TENCON 2017 - 2017 IEEE Region 10 Conference, 2017
Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these proper... more Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these properties on temperature, strain rate, and the inclusion of vacancy defects have been explored with molecular dynamics simulations using Tersoff potential. The ultimate tensile strength of pristine hexagonal boron nitride nanoribbon of 26 nm x 5 nm with armchair chirality is found to be 100.5 GPa. The ultimate tensile strength and strain have been found decreasing with increasing the temperature while an opposite trend has been observed for increasing the strain rate. Furthermore, the vacancy defects reduce ultimate tensile strength and strain where the effect of bi-vacancy is clearly dominating over point vacancy.
In this paper, we propose a multiscale numerical algorithm to simulate the hemolytic release of h... more In this paper, we propose a multiscale numerical algorithm to simulate the hemolytic release of hemoglobin (Hb) from red blood cells (RBCs) flowing through sieves containing micropores with mean diameters smaller than RBCs. Analyzing the RBC damage in microfiltration is important in the sense that it can quantify the sensitivity of human erythrocytes to mechanical hemolysis while they undergo high shear rate and high deformation. Here, the numerical simulations are carried out via lattice Boltzmann method and spring connected network (SN) coupled by an immersed boundary method. To predict the RBC sublytic damage, a sub-cellular damage model derived from molecular dynamic simulations is incorporated in the cellular solver. In the proposed algorithm, the local RBC strain distribution calculated by the cellular solver is used to obtain the pore radius on the RBC membrane. Index of hemolysis (IH) is calculated by resorting to the resulting pore radius and solving a diffusion equation considering the effects of steric hinderance and increased hydrodynamic drag due to the size of the hemoglobin molecule. It should be mentioned that current computational hemolysis models usually utilize empirical fitting of the released free hemoglobin (Hb) in plasma from damaged RBCs. These empirical correlations contain ad hoc parameters that depend on specific device and operating conditions, thus cannot be used to predict hemolysis under different conditions. In contrast to the available hemolysis model, the proposed algorithm does not have any empirical parameters. Therefore, it can predict the IH in microfilter with different sieve pore sizes and filtration pressures. Also, in contrast to empirical correlations in which the Hb release is related to shear stress and exposure time without considering the physical processes, the proposed model links flow-induced deformation of the RBC membrane to membrane permeabilization and hemoglobin release. In this paper, the cellular solver is validated by simulating optical tweezers experiment, shear flow experiment as well as an experiment to measure RBC deformability in a very narrow microchannel. Moreover, the shape of a single RBC at the rupture moment is compared with corresponding experimental data. Finally, to validate the damage model, the results obtained from our parametric study on the role of filtration pressure and sieve pore size in Hb release are compared with experimental data. Numerical results are in good agreement with experimental data. Similar to the corresponding experiment, the numerical results confirm that hemolysis increases with increasing the filtration pressure and reduction in pore size on the sieve. While in experiment, the RBC pore size cannot be measured, the numerical results Yaling Liu,
Comment on "Multiphoton induced photoluminescence during time-resolved laser-induced incandescenc... more Comment on "Multiphoton induced photoluminescence during time-resolved laser-induced incandescence experiments on silver and gold nanoparticles" [
Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019), 2021
Solder joints, an integral part in electrical appliances, undergo steady or fluctuating strain th... more Solder joints, an integral part in electrical appliances, undergo steady or fluctuating strain throughout their lifetime for which the components develop cracks and the components become susceptible to failure. Uniaxial and cyclic loading have different outcomes of damage accumulation, eventually making the electrical components susceptible to failure. In this study, the effects of two parameters (temperature and solder-alloy composition) on the uniaxial and also, for the first time, on the cyclic stress-strain behavior of lead-free solders at nanoscale were observed. A rectangular-box model of SAC (alloy of Sn, Ag and Cu), a lead-free solder, was subjected to uniaxial and cyclic (tension and compression) loading at nanoscale. The effects of uniaxial loading on SAC alloys were also observed through the simulations and the failure criterion was also observed as to get a better view on the cracks. A negative correlation between temperature and UTS (Ultimate Tensile Strength) was observed. Also, the nanoscale model was cyclically loaded under strain-controlled conditions (constant positive and negative strain limits). The study aims at determining the hysteresis loop size (area), for a stable cycle, that was calculated for a given solder alloy and varying temperature. This area represents the strain energy density dissipated per cycle, which can be correlated to the damage accumulation in the joint. In this study, most simulations were performed with SAC305. However, simulations were also performed for four SAC alloys in total (105,205,305,405) with varying silver content (1-4%) under strain-controlled cyclic loading and uniaxial loading. In addition, the effect of the temperature has also been studied by performing simulations of cyclic loading of SACN05 (N=1,2,3,4) models at six different temperatures (300, 323, 348, 373, 398 and 423K). An increase in the plastic strain range and a drop of the peak stress and loop area were found at higher temperatures.
Transient pore formation on the membrane of red blood cells (RBCs) under high mechanical tensions... more Transient pore formation on the membrane of red blood cells (RBCs) under high mechanical tensions is of great importance in many biomedical applications, such as RBC damage (hemolysis) and mechanoporation-based drug delivery. The dynamic process of pore formation, growth, and resealing is hard to visualize in experiments. We developed a mesoscale coarse-grained model to study the characteristics of transient pores on a patch of the lipid bilayer that is strengthened by an elastic meshwork representing the cytoskeleton. Unsteady molecular dynamics was used to study the pore formation and reseal at high strain rates close to the physiological ranges. The critical strain for pore formation, pore characteristics, and cytoskeleton effects were studied. Results show that the presence of the cytoskeleton increases the critical strain of pore formation and confines the pore growth. Moreover, the pore recovery process under negative strain rates (compression) is analyzed. Simulations show that pores can remain open for a long time during the high-speed tank-treading induced stretching and compression process that a patch of the RBC membrane usually experiences under high shear flow. Furthermore, complex loading conditions can affect the pore characteristics and result in denser pores. Finally, the effects of strain rate on pore formation are analyzed. Higher rate stretching of membrane patch can result in a significant increase in the critical areal strain and density of pores. Such a model reveals the dynamic molecular process of RBC damage in biomedical devices and mechanoporation that, to our knowledge, has not been reported before.
The mechanical properties of Cadmium Selenide (CdSe) nanowire is an emerging issue due to its app... more The mechanical properties of Cadmium Selenide (CdSe) nanowire is an emerging issue due to its application in semiconductor and optoelectronics industries. In this paper, we conducted molecular dynamics (MD) simulations to investigate the temperature-dependent mechanical properties and failure behavior of Zinc-Blende (ZB) CdSe nanowire under uniaxial tensile deformation. We employed Stillinger-Weber (SW) potential to describe the inter-atomic interactions. The effect of variation of temperatures (100 K-600 K), sizes, and crystal orientation on the tensile response of the CdSe nanowires is investigated. Our simulation results suggest that both ultimate tensile strength and Young's modulus of CdSe have an inverse relationship with temperature. From 100K to 600K, the ZB CdSe exhibits brittle type failure thus there is no brittle to ductile transition temperature found. Results also suggest that size has a significant effect on the mechanical properties of CdSe nanowire. It has been found that as the cross-sectional area increases both ultimate tensile stress and Young's modulus increases as well. The [111] oriented ZB CdSe shows the largest ultimate tensile strength, Young's modulus and fracture toughness whereas the values are lowest for [100] orientation. The [110] orientation shows the largest failure strain compared to other orientations. Finally, failure mechanisms of CdSe nanowire are also investigated at 100K and 600K. We noticed that at 100K temperature [100] oriented ZB CdSe fails along {111} cleavage plane however in the case of 600 K temperature, both {111} and {100} planes are activated and cause fracture of CdSe nanowire at lower strain value. This study can guide to design ZB CdSe based solar cell, optoelectronic and semiconductor devices by presenting a comprehensive understanding of the mechanical and fracture characteristics of this nanowire.
Thermal transport in defected graphene/stanene hetero-bilayer nanostructures has been investigate... more Thermal transport in defected graphene/stanene hetero-bilayer nanostructures has been investigated to encourage the optimal design of thermal and nanoelectronic devices.
COVID-19 has challenged the world’s public health and led to over 4.5 million deaths. A rapid, se... more COVID-19 has challenged the world’s public health and led to over 4.5 million deaths. A rapid, sensitive, and cost-effective point-of-care virus detection device is crucial to the control and surveillance of the contagious severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. Here we demonstrate a solid phase isothermal recombinase polymerase amplification coupled CRISPR-based (spRPA-CRISPR) assay for on-chip multiplexed, sensitive and visual COVID-19 DNA detection. By targeting the SARS-CoV-2 structure protein encoded genomes, two specific genes were simultaneously detected with the control sample without cross-interaction with other sequences. The endpoint signal can be directly visualized for rapid detection of COVID-19. The amplified target sequences were immobilized on the one-pot device surface and detected using the mixed Cas12a-crRNA collateral cleavage of reporter released fluorescent signal when specific genes were recognized. The system was tested with sa...
The constant thickness in the microfluidic channel is used for controlled absorption of red and b... more The constant thickness in the microfluidic channel is used for controlled absorption of red and blue light to measure red blood cell hemoglobin and height mapping. High speed recording of the height mapping provides us the membrane fluctuation.
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Papers by Ratul Paul