Computer simulations of realistic ion channel structures have always been challenging and
a subject of rigorous study. Simulations based on continuum electrostatics have proven to
be computationally cheap and reasonably accurate in predicting a channel’s behavior. In
this paper we discuss the use of a device simulator, SILVACO, to build a solid-state model for
KcsA channel and study its steady-state response. SILVACO is a well-established program,
typically used by electrical engineers to simulate the process flow and electrical characteristics
of solid-state devices. By employing this simulation program, we have presented an
alternative computing platform for performing ion channel simulations, besides the known
methods of writing codes in programming languages. With the ease of varying the different
parameters in the channel’s vestibule and the ability of incorporating surface charges,
we have shown the wide-ranging possibilities of using a device simulator for ion channel
simulations. Our simulated results closely agree with the experimental data, validating our
model.
Ion Channel Simulations for Potassium, Sodium, Calcium, and Chloride Channels...Iowa State University
Computer simulations of realistic ion channel structures have always been challenging and a subject of rigorous study. Simulations based on continuum electrostatics have proven to be computationally cheap and reasonably accurate in predicting a channel's behavior. In this paper we discuss the use of a device simulator, SILVACO, to build a solid-state model for KcsA channel and study its steady-state response. SILVACO is a well-established program, typically used by electrical engineers to simulate the process flow and electrical characteristics of solid-state devices. By employing this simulation program, we have presented an alternative computing platform for performing ion channel simulations, besides the known methods of writing codes in programming languages. With the ease of varying the different parameters in the channel's vestibule and the ability of incorporating surface charges, we have shown the wide-ranging possibilities of using a device simulator for ion channel simulations. Our simulated results closely agree with the experimental data, validating our model.
https://www.sciencedirect.com/science/article/abs/pii/S0169260706002276
Ion Channel Fluctuations in Transmemembrane Proteins within Cell MembranesIowa State University
The transmembrane proteins known as ion channels play a role in controlling and preserving the ionic concentrations across the cell membrane. Modeling the flux of ions in and out of these channels on an atomic level is essential for understanding several neurological diseases and related pharmaceutical discoveries. Recent experimental research has provided information on the channel's physical structure which can be used to create realistic ion transport models. Different trajectories exist for the ions entering the channel, each having its own probability of occurrence. Variables that measure these trajectories are the translocation and return probabilities, average lifetime, and spectral density of the ion number fluctuations. Theoretical analysis of ion transport has been restricted to low-resolution continuum diffusion-based or kinetic-based models which do not consider important factors that have an effect on ionic conduction. This paper extends previous models by an electro-diffusion model which takes into account the effects of electric fields, energy barriers, and rate-limited association/dissociation of ions with surface charges present inside the channel. Derived from the analytical model are the survival probability and spectral density.
The Effect of High Zeta Potentials on the Flow Hydrodynamics in Parallel-Plat...CSCJournals
This paper investigates the effect of the EDL at the solid-liquid interface on the liquid flow through a micro-channel formed by two parallel plates. The complete Poisson-Boltzmann equation (without the frequently used linear approximation) was solved analytically in order to determine the EDL field near the solid-liquid interface. The momentum equation was solved analytically taking into consideration the electrical body force resulting from the EDL field. Effects of the channel size and the strength of the zeta-potential on the electrostatic potential, the streaming potential, the velocity profile, the volume flow rate, and the apparent viscosity are presented and discussed. Results of the present analysis, which are based on the complete Poisson-Boltzmann equation, are compared with a simplified analysis that used a linear approximation of the Poisson-Boltzmann equation.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Pentacene-Based Organic Field-Effect Transistors: Analytical Model and Simula...IDES Editor
Organic Field-Effect Transistors, OFETs, attract
much interest recently and their proficiency and hence
applications are being enhanced increasingly. However, only
analytical model of old field-effect transistors, developed for
silicon-based transistors, and their relevant numerical
analyses have been used for such devices, so far. Increasing
precision of such models and numerical methods are essential
now in order to modify OFETs and propose more effective
models and methods. This study pegs at comparing current
analytical model, simulation methods and experiment data
and their fitness with each other. Certainly, four aspects of
results of three abovementioned approaches were examined
comparatively: sub-threshold slope, on-state drain current,
threshold voltage and carrier mobility. We embark to analyze
related experiment data of OFETs made by pentacene, as the
organic material, along with various organic gate insulators
including CyEP, PVP, PMMA, Parylene-C and Polyimide and
then to offer their results, comparatively.
Ion Channel Simulations for Potassium, Sodium, Calcium, and Chloride Channels...Iowa State University
Computer simulations of realistic ion channel structures have always been challenging and a subject of rigorous study. Simulations based on continuum electrostatics have proven to be computationally cheap and reasonably accurate in predicting a channel's behavior. In this paper we discuss the use of a device simulator, SILVACO, to build a solid-state model for KcsA channel and study its steady-state response. SILVACO is a well-established program, typically used by electrical engineers to simulate the process flow and electrical characteristics of solid-state devices. By employing this simulation program, we have presented an alternative computing platform for performing ion channel simulations, besides the known methods of writing codes in programming languages. With the ease of varying the different parameters in the channel's vestibule and the ability of incorporating surface charges, we have shown the wide-ranging possibilities of using a device simulator for ion channel simulations. Our simulated results closely agree with the experimental data, validating our model.
https://www.sciencedirect.com/science/article/abs/pii/S0169260706002276
Ion Channel Fluctuations in Transmemembrane Proteins within Cell MembranesIowa State University
The transmembrane proteins known as ion channels play a role in controlling and preserving the ionic concentrations across the cell membrane. Modeling the flux of ions in and out of these channels on an atomic level is essential for understanding several neurological diseases and related pharmaceutical discoveries. Recent experimental research has provided information on the channel's physical structure which can be used to create realistic ion transport models. Different trajectories exist for the ions entering the channel, each having its own probability of occurrence. Variables that measure these trajectories are the translocation and return probabilities, average lifetime, and spectral density of the ion number fluctuations. Theoretical analysis of ion transport has been restricted to low-resolution continuum diffusion-based or kinetic-based models which do not consider important factors that have an effect on ionic conduction. This paper extends previous models by an electro-diffusion model which takes into account the effects of electric fields, energy barriers, and rate-limited association/dissociation of ions with surface charges present inside the channel. Derived from the analytical model are the survival probability and spectral density.
The Effect of High Zeta Potentials on the Flow Hydrodynamics in Parallel-Plat...CSCJournals
This paper investigates the effect of the EDL at the solid-liquid interface on the liquid flow through a micro-channel formed by two parallel plates. The complete Poisson-Boltzmann equation (without the frequently used linear approximation) was solved analytically in order to determine the EDL field near the solid-liquid interface. The momentum equation was solved analytically taking into consideration the electrical body force resulting from the EDL field. Effects of the channel size and the strength of the zeta-potential on the electrostatic potential, the streaming potential, the velocity profile, the volume flow rate, and the apparent viscosity are presented and discussed. Results of the present analysis, which are based on the complete Poisson-Boltzmann equation, are compared with a simplified analysis that used a linear approximation of the Poisson-Boltzmann equation.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Pentacene-Based Organic Field-Effect Transistors: Analytical Model and Simula...IDES Editor
Organic Field-Effect Transistors, OFETs, attract
much interest recently and their proficiency and hence
applications are being enhanced increasingly. However, only
analytical model of old field-effect transistors, developed for
silicon-based transistors, and their relevant numerical
analyses have been used for such devices, so far. Increasing
precision of such models and numerical methods are essential
now in order to modify OFETs and propose more effective
models and methods. This study pegs at comparing current
analytical model, simulation methods and experiment data
and their fitness with each other. Certainly, four aspects of
results of three abovementioned approaches were examined
comparatively: sub-threshold slope, on-state drain current,
threshold voltage and carrier mobility. We embark to analyze
related experiment data of OFETs made by pentacene, as the
organic material, along with various organic gate insulators
including CyEP, PVP, PMMA, Parylene-C and Polyimide and
then to offer their results, comparatively.
The action potential signal of nerve and muscle is produced by voltage sensitive channels that include a specialized device to sense voltage. Gating currents of the voltage sensor are now known to depend on the back-and-forth movements of positively charged arginines through the hydrophobic plug of a voltage sensor domain. Transient movements of these permanently charged arginines, caused by the change of transmembrane potential, further drag the S4 segment and induce opening/closing of ion conduction pore by moving the S4-S5 linker. The ion conduction pore is a separate device from the voltage sensor, linked (in an unknown way) by the mechanical motion and electric field changes of the S4-S5 linker. This moving permanent charge induces capacitive current flow everywhere. Everything interacts with everything else in the voltage sensor so everything must interact with everything else in its mathematical model, as everything does in the whole protein. A PNP-steric model of arginines and a mechanical model for the S4 segment are combined using energy variational methods in which all movements of charge and mass satisfy conservation laws of current and mass. The resulting 1D continuum model is used to compute gating currents under a wide range of conditions, corresponding to experimental situations. Chemical-reaction-type models based on ordinary differential equations cannot capture such interactions with one set of parameters. Indeed, they may inadvertently violate conservation of current. Conservation of current is particularly important since small violations (<0.01%) quickly (<< 10-6 seconds) produce forces that destroy molecules. Our model reproduces signature properties of gating current: (1) equality of on and off charge in gating current (2) saturating voltage dependence in QV curve and (3) many (but not all) details of the shape of gating current as a function of voltage.
Multi Qubit Transmission in Quantum Channels Using Fibre Optics Synchronously...researchinventy
A quantum channel can be used to transmit classical information as well as to deliver quantum data from one location to another . Classical information theory is a subset of Quantum information theory which is fundamentally richer, because quantum mechanics includes so many more elementary classes of static and dynamic resources. Quantum information theory contains many more facts other than described here, including the study of quantum data processing, manipulation and Quantum data compression. Here we consider quantum channel as Bosonic channels, which are a quantum-mechanical model for free space or fibre optic communication. In this paper the overview of theoretical scenario of quantum networks in particular to multiple user access to the quantum communication channel is considered. Multiple qubits are generated in different system, the proper alignment of qubits is a must it can be first come first serve or round robin fashion. The received data are grouped into codewords each of n qubits and quantum error correction is performed. These codewords are agreed between the transmitter and the receiver before transmitting over the quantum channel known as valid codewords.
Numerical Simulation and Prediction for Steep Water Gravity Waves of Arbitrar...CSCJournals
Nonlinear permanent progressive wave is one of the most important applications in water waves. In this study, analytic formulation of the steep water gravity waves is presented. Abohadima and Isobe [1] showed that Cokelet solution [2] is the most accurate among many other solutions. Due to the nonlinearity of analytic equations, the need to numeric simulation is raised up. In the current paper, consequence numerical models, using one of the artificial intelligence techniques, are designed to simulate and then predict the non linear properties of permanent steep water waves. Artificial Neural Network (ANN), one of the artificial intelligence techniques, is introduced in the current paper to simulate and predict the wave celerity, momentum, energy and other wave integral properties for any permanent waves in water of arbitrary uniform depth. The ANN results presented in the current study showed that ANN technique, with less effort, is very efficiently capable of simulating and predicting the non linear properties of permanent steep water waves.
The name PNP was introduced by Eisenberg and Chen because it has important physical meaning beyond being the first letters of Poisson-Nernst-Planck. PNP also means Positive-Negative-Positive, the signs of majority current carriers in different regions of a PNP bipolar transistor. PNP transistors are two diodes in series PN + NP that rectify by changing the shape of the electric field. Transistors can function as quite different types of nonlinear devices by changing the shape of the electric field. Those realities motivated Eisenberg and Chen to introduce the name PNP.
The pun “PNP = Poisson-Nernst-Planck = Positive-Negative-Positive” has physical content. It suggests that Poisson-Nernst-Planck systems like open ionic channels should not be assumed to have constant electric fields. The electric field should be studied and computed because its change of shape is likely to be important in the function of biological systems, as it is in semiconductor systems.
A Hybrid Model to Predict Electron and Ion Distributions in Entire Interelect...Fa-Gung Fan
Atmospheric direct current (dc) corona discharge
from thin wires or sharp needles has been widely used as an ion
source in many devices such as photocopiers, laser printers, and
electronic air cleaners. Existing numerical models to predict the
electron distribution in the corona plasma are based on charge
continuity equations and the simplified Boltzmann equation. In
this paper, negative dc corona discharges produced from a thin
wire in dry air are modeled using a hybrid model of modified
particle-in-cell plus Monte Carlo collision (PIC-MCC) and a
continuum approach. The PIC-MCC model predicts densities of
charge carriers and electron kinetic energy distributions in the
plasma region, while the continuum model predicts the densities of
charge carriers in the unipolar ion region. Results from the hybrid
model are compared with those from prior continuum models.
Superior to the prior continuum model, the hybrid model is able
to predict the voltage–current curve of corona discharges. The
PIC-MCC simulation results also suggest the validity of the local
approximation used to solve the Boltzmann equation in the prior
continuum model.
Wireless power transfer (WPT) is a technique introduced to transfer power wirelessly. Generally, WPT systems are characterized by low efficiency and low output power. Since WPT process depends mainly on mutual coupling between transmitting and receiving coils in addition to load requirements, it is focused in this work toward enhancing the mutual coupling and conditioning the receiving circuit so as to optimally satisfy the load demand. The mutual coupling between transmitting and receiving nodes is enhanced via inserting three resonating circuits along with energy transmission path and conditioning the receiving circuit such that it accomplishes delivering maximum power to the load node. In this work, an adaptive efficient WPT system is introduced. This system is carried out on PSpice and validated experimentally. Both simulative and experimental WPT systems have accomplished significant enhancement in efficiency. The proposed WPT system has three resonators and three parallel connected identical receiving coils located at 6.61m from the power transmitter. The efficiency enhancement approaches thousands of times the efficiency of a conventional WPT system having similar power transmitter located at the same distance from the receiving circuit, which has a single coil identical to those in the proposed efficient WPT system.
Effect of mesh grid structure in reducing hot carrier effect of nmos device s...ijcsa
This paper presents the critical effect of mesh grid that should be considered during process and device
simulation using modern TCAD tools in order to develop and optimize their accurate electrical
characteristics. Here, the computational modelling process of developing the NMOS device structure is
performed in Athena and Atlas. The effect of Mesh grid on net doping profile, n++, and LDD sheet
resistance that could link to unwanted “Hot Carrier Effect” were investigated by varying the device grid
resolution in both directions. It is found that y-grid give more profound effect in the doping concentration,
the junction depth formation and the value of threshold voltage during simulation. Optimized mesh grid is
obtained and tested for more accurate and faster simulation. Process parameter (such as oxide thicknesses
and Sheet resistance) as well as Device Parameter (such as linear gain “beta” and SPICE level 3 mobility
roll-off parameter “ Theta”) are extracted and investigated for further different applications.
Molecular Mean-Field Theory of Ionic Solutions: a Poisson-Nernst-Planck-Biker...Bob Eisenberg
We have developed a molecular mean-field theory — fourth-order Poisson-
Nernst-Planck-Bikerman theory — for modeling ionic and water flows in biological ion channels
by treating ions and water molecules of any volume and shape with interstitial voids,
polarization of water, and ion-ion and ion-water correlations. The theory can also be used to
study thermodynamic and electrokinetic properties of electrolyte solutions in batteries, fuel
cells, nanopores, porous media including cement, geothermal brines, the oceanic system, etc.
The theory can compute electric and steric energies from all atoms in a protein and all ions
and water molecules in a channel pore while keeping electrolyte solutions in the extra- and
intracellular baths as a continuum dielectric medium with complex properties that mimic
experimental data. The theory has been verified with experiments and molecular dynamics
data from the gramicidin A channel, L-type calcium channel, potassium channel, and
sodium/calcium exchanger with real structures from the Protein Data Bank. It was also
verified with the experimental or Monte Carlo data of electric double-layer differential capacitance
and ion activities in aqueous electrolyte solutions. We give an in-depth review of
the literature about the most novel properties of the theory, namely, Fermi distributions of
water and ions as classical particles with excluded volumes and dynamic correlations that
depend on salt concentration, composition, temperature, pressure, far-field boundary conditions
etc. in a complex and complicated way as reported in a wide range of experiments.
The dynamic correlations are self-consistent output functions from a fourth-order differential
operator that describes ion-ion and ion-water correlations, the dielectric response (permit2
tivity) of ionic solutions, and the polarization of water molecules with a single correlation
length parameter.
1. INTRODUCTION
Water and ions give life. Their electrostatic and kinetic interactions play essential roles
in biological and chemical systems such as DNA, proteins, ion channels, cell membranes,
The Effect of RF Power on ion current and sheath current by electrical circui...irjes
Plasma is very important in the development of technology as it is applied in many electronic devices
such as global positioning system (GPS). In addition, fusion and process of plasma requires important elements,
namely, the electron energy distribution. However, plasma glow is a relatively new research field in physics.
There has not been found any previous study on the electric plasma modeling. Thus, this study was aimed to
study plasma modeling especially to find out what was the difference in the number of density and the
temperature of the electron in the plasma glow before and after heated and to discover how was the distribution
of electron and ion in the plasma. This research was conducted at Brawijaya University, Malang, Indonesia in
the Faculty of Science. This exploration began in the middle of June 2013. The data collection and data analysis
were done during a year around until August 2014. In this research, characteristics of plasma were studied to
build model of plasma. It utilized MATLAB dialect program examination framework which result in the
distribution of temperature and current density. The findings show that there has been a large increase in the
number of U, U2 with power, while figures of U1 is stable until middle of curve and then decrease as u but u2
after increase at point then stable. The differences appearing are probably due to the simplifying assumptions
considered in the present model. There was a curve between current in sheath and plasma. And time and sheath
current increased in the beginning then decreased before they experienced another increase.
High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon‐Opti...xingangahu
High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon‐Optical and Plasmon‐Electrical Effects from Plasmonic Asymmetric Modes of Gold Nanostars
In this review, we focus on the hardware and software technologies used for the purpose of gastrointestinal tract monitoring in a safe and comfortable manner. We review the FDA guidelines for ingestible wireless telemetric medical devices, and the features incorporated in capsule systems such as microrobotics, closed-loop feedback, physiological sensing, nerve stimulation, sampling and delivery, panoramic imaging and rapid reading software. Both experimental and commercialized capsule systems with their sensors, devices, and circuits are discussed. Furthermore, the advances in biocompatible materials and batteries, edible electronics and alternative energy sources for ingestible capsule systems are presented. The clinical studies are reviewed to examine the safety and effectiveness of capsule procedures and the current challenges and outlook are summarized.
Dylan Miley*, Leonardo Bertoncello Machado*, Calvin Condo, Albert E. Jergens, Kyoung-Jin Yoon, Santosh Pandey, “Video Capsule Endoscopy and Ingestible Electronics: Emerging Trends in Sensors, Circuits, Materials, Telemetry, Optics, and Rapid Reading Software“, Advanced Devices & Instrumentation, (Science Partner Journal), Volume 2021, Article ID 9854040, 2021. https://spj.science.org/doi/10.34133/2021/9854040?permanently=true
https://doi.org/10.34133/2021/9854040
Antimicrobial resistance studies in low-cost microfluidic chipsIowa State University
By utilizing a low-cost engineering tool, we have created a microfluidic platform to study bacteria at the single cell level, allowing us to unlock insights into microbial physiology and genetics that would otherwise not be possible. The platform is composed of 3D devices made of adhesive tapes, an agarose membrane as the resting substrate, a temperature-controlled environmental chamber, and an autofocusing module. With this technology, we have been able to observe Escherichia coli morphological changes during ampicillin exposure and measure the minimum inhibitory concentration of the antibiotic. Additionally, we have been able to use CRISPR interference (CRISPRi) to evaluate gene regulation in a concentration gradient. Overall, our microfluidic platform provides a powerful, low-cost tool to uncover new genetic determinants of antibiotic susceptibility and assess the long-term effectiveness of antibiotics in bacterial cultures.
Adhesive Tape Microfluidics with an Autofocusing Module That Incorporates CRISPR Interference: Applications to Long-Term Bacterial Antibiotic Studies, Taejoon Kong, Nicholas Backes, Upender Kalwa, Christopher Legner, Gregory J. Phillips, and Santosh Pandey, ACS Sensors 2019 4 (10), 2638-2645
https://doi.org/10.1021/acssensors.9b01031
https://pubs.acs.org/doi/full/10.1021/acssensors.9b01031
The action potential signal of nerve and muscle is produced by voltage sensitive channels that include a specialized device to sense voltage. Gating currents of the voltage sensor are now known to depend on the back-and-forth movements of positively charged arginines through the hydrophobic plug of a voltage sensor domain. Transient movements of these permanently charged arginines, caused by the change of transmembrane potential, further drag the S4 segment and induce opening/closing of ion conduction pore by moving the S4-S5 linker. The ion conduction pore is a separate device from the voltage sensor, linked (in an unknown way) by the mechanical motion and electric field changes of the S4-S5 linker. This moving permanent charge induces capacitive current flow everywhere. Everything interacts with everything else in the voltage sensor so everything must interact with everything else in its mathematical model, as everything does in the whole protein. A PNP-steric model of arginines and a mechanical model for the S4 segment are combined using energy variational methods in which all movements of charge and mass satisfy conservation laws of current and mass. The resulting 1D continuum model is used to compute gating currents under a wide range of conditions, corresponding to experimental situations. Chemical-reaction-type models based on ordinary differential equations cannot capture such interactions with one set of parameters. Indeed, they may inadvertently violate conservation of current. Conservation of current is particularly important since small violations (<0.01%) quickly (<< 10-6 seconds) produce forces that destroy molecules. Our model reproduces signature properties of gating current: (1) equality of on and off charge in gating current (2) saturating voltage dependence in QV curve and (3) many (but not all) details of the shape of gating current as a function of voltage.
Multi Qubit Transmission in Quantum Channels Using Fibre Optics Synchronously...researchinventy
A quantum channel can be used to transmit classical information as well as to deliver quantum data from one location to another . Classical information theory is a subset of Quantum information theory which is fundamentally richer, because quantum mechanics includes so many more elementary classes of static and dynamic resources. Quantum information theory contains many more facts other than described here, including the study of quantum data processing, manipulation and Quantum data compression. Here we consider quantum channel as Bosonic channels, which are a quantum-mechanical model for free space or fibre optic communication. In this paper the overview of theoretical scenario of quantum networks in particular to multiple user access to the quantum communication channel is considered. Multiple qubits are generated in different system, the proper alignment of qubits is a must it can be first come first serve or round robin fashion. The received data are grouped into codewords each of n qubits and quantum error correction is performed. These codewords are agreed between the transmitter and the receiver before transmitting over the quantum channel known as valid codewords.
Numerical Simulation and Prediction for Steep Water Gravity Waves of Arbitrar...CSCJournals
Nonlinear permanent progressive wave is one of the most important applications in water waves. In this study, analytic formulation of the steep water gravity waves is presented. Abohadima and Isobe [1] showed that Cokelet solution [2] is the most accurate among many other solutions. Due to the nonlinearity of analytic equations, the need to numeric simulation is raised up. In the current paper, consequence numerical models, using one of the artificial intelligence techniques, are designed to simulate and then predict the non linear properties of permanent steep water waves. Artificial Neural Network (ANN), one of the artificial intelligence techniques, is introduced in the current paper to simulate and predict the wave celerity, momentum, energy and other wave integral properties for any permanent waves in water of arbitrary uniform depth. The ANN results presented in the current study showed that ANN technique, with less effort, is very efficiently capable of simulating and predicting the non linear properties of permanent steep water waves.
The name PNP was introduced by Eisenberg and Chen because it has important physical meaning beyond being the first letters of Poisson-Nernst-Planck. PNP also means Positive-Negative-Positive, the signs of majority current carriers in different regions of a PNP bipolar transistor. PNP transistors are two diodes in series PN + NP that rectify by changing the shape of the electric field. Transistors can function as quite different types of nonlinear devices by changing the shape of the electric field. Those realities motivated Eisenberg and Chen to introduce the name PNP.
The pun “PNP = Poisson-Nernst-Planck = Positive-Negative-Positive” has physical content. It suggests that Poisson-Nernst-Planck systems like open ionic channels should not be assumed to have constant electric fields. The electric field should be studied and computed because its change of shape is likely to be important in the function of biological systems, as it is in semiconductor systems.
A Hybrid Model to Predict Electron and Ion Distributions in Entire Interelect...Fa-Gung Fan
Atmospheric direct current (dc) corona discharge
from thin wires or sharp needles has been widely used as an ion
source in many devices such as photocopiers, laser printers, and
electronic air cleaners. Existing numerical models to predict the
electron distribution in the corona plasma are based on charge
continuity equations and the simplified Boltzmann equation. In
this paper, negative dc corona discharges produced from a thin
wire in dry air are modeled using a hybrid model of modified
particle-in-cell plus Monte Carlo collision (PIC-MCC) and a
continuum approach. The PIC-MCC model predicts densities of
charge carriers and electron kinetic energy distributions in the
plasma region, while the continuum model predicts the densities of
charge carriers in the unipolar ion region. Results from the hybrid
model are compared with those from prior continuum models.
Superior to the prior continuum model, the hybrid model is able
to predict the voltage–current curve of corona discharges. The
PIC-MCC simulation results also suggest the validity of the local
approximation used to solve the Boltzmann equation in the prior
continuum model.
Wireless power transfer (WPT) is a technique introduced to transfer power wirelessly. Generally, WPT systems are characterized by low efficiency and low output power. Since WPT process depends mainly on mutual coupling between transmitting and receiving coils in addition to load requirements, it is focused in this work toward enhancing the mutual coupling and conditioning the receiving circuit so as to optimally satisfy the load demand. The mutual coupling between transmitting and receiving nodes is enhanced via inserting three resonating circuits along with energy transmission path and conditioning the receiving circuit such that it accomplishes delivering maximum power to the load node. In this work, an adaptive efficient WPT system is introduced. This system is carried out on PSpice and validated experimentally. Both simulative and experimental WPT systems have accomplished significant enhancement in efficiency. The proposed WPT system has three resonators and three parallel connected identical receiving coils located at 6.61m from the power transmitter. The efficiency enhancement approaches thousands of times the efficiency of a conventional WPT system having similar power transmitter located at the same distance from the receiving circuit, which has a single coil identical to those in the proposed efficient WPT system.
Effect of mesh grid structure in reducing hot carrier effect of nmos device s...ijcsa
This paper presents the critical effect of mesh grid that should be considered during process and device
simulation using modern TCAD tools in order to develop and optimize their accurate electrical
characteristics. Here, the computational modelling process of developing the NMOS device structure is
performed in Athena and Atlas. The effect of Mesh grid on net doping profile, n++, and LDD sheet
resistance that could link to unwanted “Hot Carrier Effect” were investigated by varying the device grid
resolution in both directions. It is found that y-grid give more profound effect in the doping concentration,
the junction depth formation and the value of threshold voltage during simulation. Optimized mesh grid is
obtained and tested for more accurate and faster simulation. Process parameter (such as oxide thicknesses
and Sheet resistance) as well as Device Parameter (such as linear gain “beta” and SPICE level 3 mobility
roll-off parameter “ Theta”) are extracted and investigated for further different applications.
Molecular Mean-Field Theory of Ionic Solutions: a Poisson-Nernst-Planck-Biker...Bob Eisenberg
We have developed a molecular mean-field theory — fourth-order Poisson-
Nernst-Planck-Bikerman theory — for modeling ionic and water flows in biological ion channels
by treating ions and water molecules of any volume and shape with interstitial voids,
polarization of water, and ion-ion and ion-water correlations. The theory can also be used to
study thermodynamic and electrokinetic properties of electrolyte solutions in batteries, fuel
cells, nanopores, porous media including cement, geothermal brines, the oceanic system, etc.
The theory can compute electric and steric energies from all atoms in a protein and all ions
and water molecules in a channel pore while keeping electrolyte solutions in the extra- and
intracellular baths as a continuum dielectric medium with complex properties that mimic
experimental data. The theory has been verified with experiments and molecular dynamics
data from the gramicidin A channel, L-type calcium channel, potassium channel, and
sodium/calcium exchanger with real structures from the Protein Data Bank. It was also
verified with the experimental or Monte Carlo data of electric double-layer differential capacitance
and ion activities in aqueous electrolyte solutions. We give an in-depth review of
the literature about the most novel properties of the theory, namely, Fermi distributions of
water and ions as classical particles with excluded volumes and dynamic correlations that
depend on salt concentration, composition, temperature, pressure, far-field boundary conditions
etc. in a complex and complicated way as reported in a wide range of experiments.
The dynamic correlations are self-consistent output functions from a fourth-order differential
operator that describes ion-ion and ion-water correlations, the dielectric response (permit2
tivity) of ionic solutions, and the polarization of water molecules with a single correlation
length parameter.
1. INTRODUCTION
Water and ions give life. Their electrostatic and kinetic interactions play essential roles
in biological and chemical systems such as DNA, proteins, ion channels, cell membranes,
The Effect of RF Power on ion current and sheath current by electrical circui...irjes
Plasma is very important in the development of technology as it is applied in many electronic devices
such as global positioning system (GPS). In addition, fusion and process of plasma requires important elements,
namely, the electron energy distribution. However, plasma glow is a relatively new research field in physics.
There has not been found any previous study on the electric plasma modeling. Thus, this study was aimed to
study plasma modeling especially to find out what was the difference in the number of density and the
temperature of the electron in the plasma glow before and after heated and to discover how was the distribution
of electron and ion in the plasma. This research was conducted at Brawijaya University, Malang, Indonesia in
the Faculty of Science. This exploration began in the middle of June 2013. The data collection and data analysis
were done during a year around until August 2014. In this research, characteristics of plasma were studied to
build model of plasma. It utilized MATLAB dialect program examination framework which result in the
distribution of temperature and current density. The findings show that there has been a large increase in the
number of U, U2 with power, while figures of U1 is stable until middle of curve and then decrease as u but u2
after increase at point then stable. The differences appearing are probably due to the simplifying assumptions
considered in the present model. There was a curve between current in sheath and plasma. And time and sheath
current increased in the beginning then decreased before they experienced another increase.
High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon‐Opti...xingangahu
High Efficiency Organic Solar Cells Achieved by the Simultaneous Plasmon‐Optical and Plasmon‐Electrical Effects from Plasmonic Asymmetric Modes of Gold Nanostars
In this review, we focus on the hardware and software technologies used for the purpose of gastrointestinal tract monitoring in a safe and comfortable manner. We review the FDA guidelines for ingestible wireless telemetric medical devices, and the features incorporated in capsule systems such as microrobotics, closed-loop feedback, physiological sensing, nerve stimulation, sampling and delivery, panoramic imaging and rapid reading software. Both experimental and commercialized capsule systems with their sensors, devices, and circuits are discussed. Furthermore, the advances in biocompatible materials and batteries, edible electronics and alternative energy sources for ingestible capsule systems are presented. The clinical studies are reviewed to examine the safety and effectiveness of capsule procedures and the current challenges and outlook are summarized.
Dylan Miley*, Leonardo Bertoncello Machado*, Calvin Condo, Albert E. Jergens, Kyoung-Jin Yoon, Santosh Pandey, “Video Capsule Endoscopy and Ingestible Electronics: Emerging Trends in Sensors, Circuits, Materials, Telemetry, Optics, and Rapid Reading Software“, Advanced Devices & Instrumentation, (Science Partner Journal), Volume 2021, Article ID 9854040, 2021. https://spj.science.org/doi/10.34133/2021/9854040?permanently=true
https://doi.org/10.34133/2021/9854040
Antimicrobial resistance studies in low-cost microfluidic chipsIowa State University
By utilizing a low-cost engineering tool, we have created a microfluidic platform to study bacteria at the single cell level, allowing us to unlock insights into microbial physiology and genetics that would otherwise not be possible. The platform is composed of 3D devices made of adhesive tapes, an agarose membrane as the resting substrate, a temperature-controlled environmental chamber, and an autofocusing module. With this technology, we have been able to observe Escherichia coli morphological changes during ampicillin exposure and measure the minimum inhibitory concentration of the antibiotic. Additionally, we have been able to use CRISPR interference (CRISPRi) to evaluate gene regulation in a concentration gradient. Overall, our microfluidic platform provides a powerful, low-cost tool to uncover new genetic determinants of antibiotic susceptibility and assess the long-term effectiveness of antibiotics in bacterial cultures.
Adhesive Tape Microfluidics with an Autofocusing Module That Incorporates CRISPR Interference: Applications to Long-Term Bacterial Antibiotic Studies, Taejoon Kong, Nicholas Backes, Upender Kalwa, Christopher Legner, Gregory J. Phillips, and Santosh Pandey, ACS Sensors 2019 4 (10), 2638-2645
https://doi.org/10.1021/acssensors.9b01031
https://pubs.acs.org/doi/full/10.1021/acssensors.9b01031
Flexible chip for long-term antimicrobial resistance experimentsIowa State University
By creating a low-cost, three-dimensional microfluidic platform, we have improved our ability to study bacterial cells at the single cell level. This technology allows for prolonged culturing of bacteria in a controlled environment, as well as high resolution observation and imaging of cells. We have used this platform to examine morphological changes in Escherichia coli exposed to ampicillin and to quantify the minimum inhibitory concentration of the antibiotic. Additionally, we demonstrated the potential for precise gene regulation using CRISPR interference (CRISPRi) in a concentration gradient. Ultimately, this engineering tool should be useful for uncovering new genetic factors that influence antibiotic susceptibility and evaluating the long-term effectiveness of antibiotics.
Adhesive Tape Microfluidics with an Autofocusing Module That Incorporates CRISPR Interference: Applications to Long-Term Bacterial Antibiotic Studies, Taejoon Kong, Nicholas Backes, Upender Kalwa, Christopher Legner, Gregory J. Phillips, and Santosh Pandey, ACS Sensors 2019 4 (10), 2638-2645
https://doi.org/10.1021/acssensors.9b01031
https://pubs.acs.org/doi/full/10.1021/acssensors.9b01031
In this paper, we explore the use of microfluidic paper-based analytical devices (PADs) to study the behavior of Caenorhabditis elegans. We show how these devices can be fabricated on paper and plastic substrates, as well as how to load, visualize, and transfer single and multiple nematodes. We also demonstrate the use of anthelmintic drug, levamisole, to perform chemical testing on C. elegans. Furthermore, we provide a custom program that is able to recognize individual worms on the PADs in real-time and extract their locomotion parameters. This combination of PADs and the nematode tracking program creates a low-cost, easy-to-fabricate imaging and screening assay that is superior to standard agarose plates or polymeric microfluidic devices for non-microfluidic, nematode laboratories.
Zach Njus, Taejoon Kong, Upender Kalwa, Christopher Legner, Matthew Weinstein, Shawn Flanigan, Jenifer Saldanha, and Santosh Pandey, "Flexible and disposable paper- and plastic-based gel micropads for nematode handling, imaging, and chemical testing", APL Bioengineering 1, 016102 (2017)
https://doi.org/10.1063/1.5005829
https://aip.scitation.org/doi/10.1063/1.5005829
The resistance of parasites to existing drugs and the availability of better technology platforms has driven the discovery of new drugs. Microfluidic devices have been used to facilitate faster screening of compounds, controlled sampling/sorting of whole animals, and automated behavioral pattern recognition. In most cases, drug effects on small creatures (e.g., Caenorhabditis elegans) are measuredelegant by a single parameter such as worm velocity or stroke frequency. We present a multi-parameter extraction method to characterize modes of paralysis in C. elegans over a longer duration. This was done using a microfluidic device featuring real-time imaging, exposing worms to four anthelmintic drugs at EC75, where 75% of the worm population is affected. We monitored the worms' behavior with metrics such as curls per second, types of paralyzation, mode frequency, and number/duration of active/immobilization periods. Differences were observed in how the worms paralyzed in the various drug environments at equivalent concentrations. This study highlights the importance of assessing drug effects on small animals with multiple parameters, measured at regular intervals over a prolonged period, to accurately detect resistance and adaptability in chemical environments.
Roy Lycke, Archana Parashar, and Santosh Pandey, "Microfluidics-enabled method to identify modes of Caenorhabditis elegans paralysis in four anthelmintics", Biomicrofluidics 7, 064103 (2013).
https://doi.org/10.1063/1.4829777
https://aip.scitation.org/doi/10.1063/1.4829777
Melanoma is a particularly dangerous type of skin cancer and is hard to treat in its later stages. Therefore, early detection is key in reducing mortality rates. In order to assist dermatologists in doing this, computer-aided systems have been designed for desktop computers. However, there is a desire for the development of mobile, at-home diagnostics for melanoma risk assessment. Here, we introduce a smartphone application that captures images and extracts ABCD features to classify skin lesions as either malignant or benign. The algorithms used are adaptive to make the process light and user-friendly, as well as reliable in diagnosis. Images can be taken with the phone's camera or imported from public datasets. The entire process of taking the image, performing preprocessing, segmentation and classification is completed on an Android smartphone in a short time. Our application is evaluated on a dataset of 200 images, and achieved either comparable or better performance metrics than other methods. Additionally, it is easy-to-download and easy-to-navigate for the user, which is important for the widespread use of such diagnostics.
Kalwa, U.; Legner, C.; Kong, T.; Pandey, S. Skin Cancer Diagnostics with an All-Inclusive Smartphone Application. Symmetry 2019, 11, 790. https://doi.org/10.3390/sym11060790
https://www.mdpi.com/2073-8994/11/6/790
A CMOS biosensor with a folded floating-gate is created to detect charged biochemical molecules. It contains a FET, a control-gate and a sensing area. The floating-gate spans the whole device, allowing the sensing area to be placed on top of the FET, resulting in a decrease of the device's total area. The device is sensitive to the polarity and quantity of charged poly amino acids and could be used for electronic recognition of temporal and spatial migration of charges, such as in biological phenomena.
B. Chen, A. Parashar and S. Pandey, "Folded Floating-Gate CMOS Biosensor for the Detection of Charged Biochemical Molecules," IEEE Sensors Journal, vol. 11, no. 11, pp. 2906-2910, Nov. 2011, doi: 10.1109/JSEN.2011.2149514.
https://ieeexplore.ieee.org/document/5762313
We attempt to offer an innovative solution to the issues of long response times, large volumes of actuation fluid, and external control circuitry that have been associated with past approaches in creating switches in paper microfluidics. Our method consists of a device created from chromatography paper and featuring folds which, when selectively wetted with an actuation fluid, will either raise or lower the actuator's tip and thus engage or break the desired fluidic connections. As a result, response time is drastically reduced (2 seconds) and the volume of actuation fluid consumed is extremely small (4 microliters). We have tested this approach with six switch configurations, ranging from single-pole single-throw (normally OFF and normally ON) to single-pole double-throw (with single and double break). We further demonstrate its potential with a colorimetric assay involving six actuators in parallel, which can detect the presence of three analytes (glucose, protein, and nitrite) in artificial saliva. Finally, this work brings in the concept of origami to paper microfluidics, combining multiple-fold geometries for programmable switching of fluidic connections.
"A fast, reconfigurable flow switch for paper
microfluidics based on selective wetting of folded
paper actuator strips",
Lab on Chip, 2017, 17, 3621
A method to create smart and flexible switches for the regulation of liquid flow across multiple channels is essential in paper microfluidics. Prior approaches are hampered by long response times, high actuation fluid volumes, and external control circuitry. To diminish these problems, we designed a distinctive actuator device fashioned entirely from chromatography paper and featuring folds. The fold can be selectively wetted by an actuation fluid at either the crest or trough, resulting in the raising or lowering of the actuator's tip and thus bringing about the connection or severance of fluidic channels. This actuation principle reduces the response time to only two seconds and the amount of fluid used to merely four microliters. We have also added six switch arrangements which can be divided into single-pole single-throw (normally OFF and normally ON) and single-pole double-throw (with single and double break). The utilization of six actuators in a parallel system allowed us to construct an autonomous colorimetric assay for the detection of three analytes - glucose, protein, and nitrite - in artificial saliva. This study has brought the concept of origami to paper microfluidics, allowing the use of multiple-fold geometries for the programmable switching of fluidic connections.
Taejoon Kong et al, "A fast, reconfigurable flow switch for paper
microfluidics based on selective wetting of folded
paper actuator strips", Lab on Chip, 2017, 17, 3621
The transmembrane proteins known as ion channels play a role in controlling and preserving the ionic concentrations across the cell membrane. Modeling the flux of ions in and out of these channels on an atomic level is essential for understanding several neurological diseases and related pharmaceutical discoveries. Recent experimental research has provided information on the channel's physical structure which can be used to create realistic ion transport models. Different trajectories exist for the ions entering the channel, each having its own probability of occurrence. Variables that measure these trajectories are the translocation and return probabilities, average lifetime, and spectral density of the ion number fluctuations. Theoretical analysis of ion transport has been restricted to low-resolution continuum diffusion-based or kinetic-based models which do not consider important factors that have an effect on ionic conduction. This paper extends previous models by an electro-diffusion model which takes into account the effects of electric fields, energy barriers, and rate-limited association/dissociation of ions with surface charges present inside the channel. Derived from the analytical model are the survival probability and spectral density.
:Analytical Modeling of the Ion Number Fluctuations in Biological Ion Channels"
Journal of Nanoscience and Nanotechnology; Vol. 12, 2489–2495, 2012
This paper presents a remote monitoring tool for the objective measurement of behavioral indicators that can help in assessing the health and welfare of pigs in precision swine production. The multiparameter electronic sensor board can measure posture, gait, vocalization, and external temperature, and has been characterized through laboratory measurements and animal tests. Machine learning algorithms and decision support tools can be implemented to detect animal lameness, lethargy, pain, injury, and distress. The adoption of this technology could lead to more efficient management of farm animals, better targeting of sick animals, lower medical costs, and fewer antibiotics being used. Challenges and a road map for technology adoption are discussed, along with suggestions for future improvements.
Animals 2021, 11(9), 2665; https://doi.org/10.3390/ani11092665
We propose a remote monitoring device for measuring behavioral indicators like posture, gait, vocalization, and external temperature which can help in evaluating the health and welfare of pigs. The multiparameter electronic sensor board was tested in a laboratory and on animals. Machine learning algorithms and decision support tools can be used to detect lameness, lethargy, pain, injury, and distress. The roadmap for technology adoption, potential benefits, and further challenges are discussed. This technology could help in efficient management of farm animals, providing targeted attention to sick animals, saving medical costs, and reducing the use of antibiotics.
"Behavioral Monitoring Tool for Pig Farmers: Ear Tag Sensors,
Machine Intelligence, and Technology Adoption Roadmap",
Animals 2021, 11, 2665.
https://doi.org/10.3390/ani11092665
In this study, two sets of experiments were conducted in order to investigate the impact of static magnetic fields on the growth and ethanol production of Saccharomyces cerevisiae. The first experiment ran for 25 hours with a 2% dextrose loading rate, while the second ran for 30 hours with a 6% dextrose loading rate. The magnetic fields used were homogeneous and non-homogeneous, with strengths of 100 mT and 200 mT, respectively. The results showed that the homogenous magnetic field had no significant effect on cell growth, whilst the non-homogeneous field yielded an increase of approximately 8% in peak ethanol concentration compared to the control.
Deutmeyer, A. , Raman, R. , Murphy, P. and Pandey, S. (2011) Effect of magnetic field on the fermentation kinetics of Saccharomyces cerevisiae. Advances in Bioscience and Biotechnology, 2, 207-213.
doi: 10.4236/abb.2011.24031.
https://www.scirp.org/journal/paperinformation.aspx?paperid=6857
Magnetic field to improve fermentation kinetics for ethanol production Iowa State University
Two experiments were conducted to analyze the influence that magnetic fields have on cell growth and ethanol production during fermentation. The first experiment was conducted for 25 hours at a 2% dextrose loading rate with a homogeneous and non-homogeneous static magnetic field of 100 mT and 200 mT, respectively. The second experiment was conducted for 30 hours at a 6% dextrose loading rate with a non-homogeneous static magnetic field of 200 mT. The results indicated that homogeneous magnetic fields did not have a significant effect on the yeast cell growth. However, the non-homogeneous static magnetic field resulted in about 8% more peak ethanol concentration than the control for the 2% dextrose loading rate.
To evaluate the severity of SCN infections in the field, population densities of nematode eggs must be calculated. A method utilizing OptiPrep as a density gradient medium has been shown to provide more effective separation and recovery of extracted eggs compared to sucrose centrifugation. Furthermore, computerized processes have been established to facilitate the discernment and enumeration of eggs from processed samples. A high-resolution scanner was employed to capture static images of eggs and debris on filter papers, and a deep learning network was trained to distinguish and count the eggs from the debris. Additionally, a lensless imaging setup was established using standard components, and the egg samples were allowed to pass through a microfluidic flow chip created from double-sided adhesive tape. Holographic videos were then recorded of the eggs and debris as they moved through, which were reconstructed and processed by a custom software program to obtain the egg counts. The software programs' efficacy for egg counting was validated using soil samples obtained from two farms, and the results were compared to those obtained through manual counting.
Kalwa U, Legner C, Wlezien E, Tylka G, Pandey S (2019) New methods of removing debris and high-throughput counting of cyst nematode eggs extracted from field soil. PLOS ONE 14(10): e0223386.
https://doi.org/10.1371/journal.pone.0223386
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223386
To evaluate the level of infestation of the soybean cyst nematode (SCN), Heterodera glycines, in the field, egg population densities are determined from soil samples. Sucrose centrifugation is a common technique for separating debris from the extracted SCN eggs. We have developed a procedure, however, that employs OptiPrep as a density gradient medium, with improved extraction and recovery of the eggs compared to the sucrose centrifugation technique. Also, we have built computerized methods to automate the identification and counting of the nematode eggs from the processed samples. One approach uses a high-resolution scanner to capture static images of the eggs and debris on filter papers and a deep learning network is trained to detect and count the eggs. The second approach utilizes a lensless imaging setup with off-the-shelf components and the egg samples flow through a microfluidic flowchip. Holographic videos are taken of the passing eggs and debris, which are then reconstructed and processed by a custom software program to calculate egg counts. To evaluate the performance of the software programs, SCN-infested soils were collected from two farms and the results were compared with manual counts.
Kalwa U, Legner C, Wlezien E, Tylka G, Pandey S (2019), New methods of removing debris and high-throughput counting of cyst nematode eggs extracted from field soil. PLOS ONE 14(10): e0223386.
https://doi.org/10.1371/journal.pone.0223386
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223386
Effect of Static Magnetic Field on Parasitic Worms in MicroChipsIowa State University
This study uses the model organism, C. elegans, to investigate its sensitivity and response to static magnetic fields. Wild-type C. elegans are put into microfluidic channels and exposed to permanent magnets for five cycles of thirty-second time intervals at field strengths ranging from 5 milli Tesla to 120 milli Tesla. Recorded and analyzed with custom software, the results of the worm's movement - the average velocity, turning and curling percentage - were compared to control experiments. Surprisingly, the results did not show any significant difference, indicating that C. elegans may not be able to sense static magnetic fields at the range of field strengths tested.
Njus, Z. , Feldmann, D. , Brien, R. , Kong, T. , Kalwa, U. and Pandey, S. (2015) Characterizing the Effect of Static Magnetic Fields on C. elegans Using Microfluidics. Advances in Bioscience and Biotechnology, 6, 583-591.
doi: 10.4236/abb.2015.69061.
https://www.scirp.org/journal/paperinformation.aspx?paperid=59434
The integration of physical and chemical sensing mechanisms found in nature has been harnessed to enable the development of wearable devices that can track the biochemical and physiological signals of the human body. Numerous consumer electronics have been developed to measure activity, posture, heart rate, respiration rate, and blood oxygen level. Sweat sampling provides a source of biomarkers that is accessible in a continuous, on-the-go, and non-invasive way, allowing for unique developments in wearable sweat sensing. This review focuses on recent trends in material science, device development, sensing mechanisms, power generation, and data management related to these devices. Additionally, exemplary wearable sweat sensors and commercialization efforts in this area are discussed, with an emphasis on the multifunctional sensing platforms that integrate data from both physical and biochemical sweat sensors.
Recent developments in wearable physical sensors have enabled the development of a number of consumer electronics products which measure parameters related to activity, posture, heart rate, respiration rate, and blood oxygen level. However, progress in the development of wearable chemical sensors has been slower due to the inherent challenges in retrieving and processing bodily fluids. Sweat is a valuable source of biomarkers which can be accessed continuously, on-the-go, and non-invasively. This review provides an overview of recent trends in the area of wearable sweat sensing, looking at topics such as material science, device development, sensing mechanisms, power generation, and data management. Examples of wearable sweat sensors published in recent years, as well as commercialization efforts in this field are also presented. The review highlights the trends in multifunctional sensing platforms which incorporate flexible electronics to integrate data from both physical and biochemical sensors.
This paper explores how the adaptability of Caenorhabditis elegans locomotion behavior can be assessed through a movement-based assay. This assay is set up with a series of sinusoidal microchannels, featuring a fixed wavelength and modulating amplitude. These channels are comparable to the body diameter of the organism, and worms are allowed to travel from the input port to the output port. In regions that closely fit the worms' natural undulations, progress is quick and steady. As the channel amplitude changes along the device, the worm struggles to generate propulsive force, slows down, and eventually is unable to move forward. An array of locomotion parameters (average forward velocity, number and duration of pauses, range of contact angle, and cut-off region) are generated from the recorded videos to measure how the worm moves in the modulated sinusoidal channels. The device is tested on wild-type (N2) and two mutant (lev-8 and unc-38) C. elegans. We suggest that this passive, movement-based assay can be used to differentiate between nematodes with distinct locomotion phenotypes.
"Amplitude-modulated sinusoidal microchannels
for observing adaptability in C. elegans locomotion",
Biomicrofluidics 5, 024112 (2011)
https://doi.org/10.1063/1.3604391
As Europe's leading economic powerhouse and the fourth-largest hashtag#economy globally, Germany stands at the forefront of innovation and industrial might. Renowned for its precision engineering and high-tech sectors, Germany's economic structure is heavily supported by a robust service industry, accounting for approximately 68% of its GDP. This economic clout and strategic geopolitical stance position Germany as a focal point in the global cyber threat landscape.
In the face of escalating global tensions, particularly those emanating from geopolitical disputes with nations like hashtag#Russia and hashtag#China, hashtag#Germany has witnessed a significant uptick in targeted cyber operations. Our analysis indicates a marked increase in hashtag#cyberattack sophistication aimed at critical infrastructure and key industrial sectors. These attacks range from ransomware campaigns to hashtag#AdvancedPersistentThreats (hashtag#APTs), threatening national security and business integrity.
🔑 Key findings include:
🔍 Increased frequency and complexity of cyber threats.
🔍 Escalation of state-sponsored and criminally motivated cyber operations.
🔍 Active dark web exchanges of malicious tools and tactics.
Our comprehensive report delves into these challenges, using a blend of open-source and proprietary data collection techniques. By monitoring activity on critical networks and analyzing attack patterns, our team provides a detailed overview of the threats facing German entities.
This report aims to equip stakeholders across public and private sectors with the knowledge to enhance their defensive strategies, reduce exposure to cyber risks, and reinforce Germany's resilience against cyber threats.
Levelwise PageRank with Loop-Based Dead End Handling Strategy : SHORT REPORT ...Subhajit Sahu
Abstract — Levelwise PageRank is an alternative method of PageRank computation which decomposes the input graph into a directed acyclic block-graph of strongly connected components, and processes them in topological order, one level at a time. This enables calculation for ranks in a distributed fashion without per-iteration communication, unlike the standard method where all vertices are processed in each iteration. It however comes with a precondition of the absence of dead ends in the input graph. Here, the native non-distributed performance of Levelwise PageRank was compared against Monolithic PageRank on a CPU as well as a GPU. To ensure a fair comparison, Monolithic PageRank was also performed on a graph where vertices were split by components. Results indicate that Levelwise PageRank is about as fast as Monolithic PageRank on the CPU, but quite a bit slower on the GPU. Slowdown on the GPU is likely caused by a large submission of small workloads, and expected to be non-issue when the computation is performed on massive graphs.
StarCompliance is a leading firm specializing in the recovery of stolen cryptocurrency. Our comprehensive services are designed to assist individuals and organizations in navigating the complex process of fraud reporting, investigation, and fund recovery. We combine cutting-edge technology with expert legal support to provide a robust solution for victims of crypto theft.
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We guide you through the process of filing a valid police report. Our support team provides detailed instructions on which police department to contact and helps you complete the necessary paperwork within the critical 72-hour window.
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Our team of experienced lawyers can initiate lawsuits on your behalf and represent you in various jurisdictions around the world. They work diligently to recover your stolen funds and ensure that justice is served.
At StarCompliance, we understand the urgency and stress involved in dealing with cryptocurrency theft. Our dedicated team works quickly and efficiently to provide you with the support and expertise needed to recover your assets. Trust us to be your partner in navigating the complexities of the crypto world and safeguarding your investments.
Chatty Kathy - UNC Bootcamp Final Project Presentation - Final Version - 5.23...John Andrews
SlideShare Description for "Chatty Kathy - UNC Bootcamp Final Project Presentation"
Title: Chatty Kathy: Enhancing Physical Activity Among Older Adults
Description:
Discover how Chatty Kathy, an innovative project developed at the UNC Bootcamp, aims to tackle the challenge of low physical activity among older adults. Our AI-driven solution uses peer interaction to boost and sustain exercise levels, significantly improving health outcomes. This presentation covers our problem statement, the rationale behind Chatty Kathy, synthetic data and persona creation, model performance metrics, a visual demonstration of the project, and potential future developments. Join us for an insightful Q&A session to explore the potential of this groundbreaking project.
Project Team: Jay Requarth, Jana Avery, John Andrews, Dr. Dick Davis II, Nee Buntoum, Nam Yeongjin & Mat Nicholas
Opendatabay - Open Data Marketplace.pptxOpendatabay
Opendatabay.com unlocks the power of data for everyone. Open Data Marketplace fosters a collaborative hub for data enthusiasts to explore, share, and contribute to a vast collection of datasets.
First ever open hub for data enthusiasts to collaborate and innovate. A platform to explore, share, and contribute to a vast collection of datasets. Through robust quality control and innovative technologies like blockchain verification, opendatabay ensures the authenticity and reliability of datasets, empowering users to make data-driven decisions with confidence. Leverage cutting-edge AI technologies to enhance the data exploration, analysis, and discovery experience.
From intelligent search and recommendations to automated data productisation and quotation, Opendatabay AI-driven features streamline the data workflow. Finding the data you need shouldn't be a complex. Opendatabay simplifies the data acquisition process with an intuitive interface and robust search tools. Effortlessly explore, discover, and access the data you need, allowing you to focus on extracting valuable insights. Opendatabay breaks new ground with a dedicated, AI-generated, synthetic datasets.
Leverage these privacy-preserving datasets for training and testing AI models without compromising sensitive information. Opendatabay prioritizes transparency by providing detailed metadata, provenance information, and usage guidelines for each dataset, ensuring users have a comprehensive understanding of the data they're working with. By leveraging a powerful combination of distributed ledger technology and rigorous third-party audits Opendatabay ensures the authenticity and reliability of every dataset. Security is at the core of Opendatabay. Marketplace implements stringent security measures, including encryption, access controls, and regular vulnerability assessments, to safeguard your data and protect your privacy.
2. 2 computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7
molecules are treated as a continuum. Collisions between the
ions and the surrounding water molecules are mimicked by
random fluctuating forces plus an average frictional force. A
major advantage of Brownian dynamic approach is the ability
to allow direct simulation of ion–ion interaction and calculate
an ion’s interaction energy with respect to the system during
each time step [7]. But this has always been an involved, time-
consuming process [9].
Using a mean field approximation, continuum electrostat-
ics provides a rather simplistic alternative to ion channel mod-
eling [10]. It involves solving the Poisson–Nernst–Planck (PNP)
equations for the charge distribution inside the channel, and
has proven to be very computationally cheap. Even though
the PNP method uses a major approximation of reducing the
ion–ion interactions to an interaction between an ion and a
mean field, its results have shown to be in good agreement
with the experimental data [11,12].
In this paper we present a novel method of simulating
ion channels based on continuum electrostatics. We have
attempted to represent the structure of a KcsA channel as a
solid-state device, with its intrinsic material properties similar
to that in the realistic case [13,14]. Simulations are performed
on a solid-state device simulator, SILVACO International, pro-
viding us with the steady-state behavior of the KcsA channel.
The simulation results agree well with the available experi-
mental data.
2. Methods
2.1. Poisson–Nernst–Planck (PNP) theory
The PNP approach to ion permeation in membrane channels
has been studied in numerous works [10,11,15]. The PNP equa-
tions are similar to the drift–diffusion equations that describe
the carrier dynamics in semiconductors [16]. The flux J of each
ion species is described by the Nernst–Planck (NP) equation,
which combines the diffusion due to a concentration gradient
with the potential gradient [16,17]:
J = −D
∇n +
zen
kT
∇
(1)
where D is the diffusion coefficient, z the valency of the ion,
e the electronic charge, k the Boltzmann constant, T the tem-
perature, n the concentration of the ion, and ˚ is the potential.
Also, the Poisson’s equation is written as [16,17]:
ε0∇[ε(r)∇(r)] = −
ions
zen − ex (2)
where ε(r) is the dielectric constant at an axial distance, r the
sum over all ions gives the total mobile charge, ε0 the dielectric
constant of free space, and ex represents all the external fixed
and induced charges. It is to be noted that, realistically, all the
quantities in Eqs. (1) and (2) are varying along the ion chan-
nel axis [12,13]. This makes it notoriously difficult to obtain
any analytical solution of the PNP equations, besides in some
very specific cases [10]. However, it is possible to solve Eqs.
(1) and (2) iteratively and obtain self-consistent solutions for
the potential, concentrations and fluxes of the ions along the
channel axis [17]. Even though this paper deals with 1D PNP
computations, it has been shown that the PNP equations can
be extended to 3D with a more realistic channel representa-
tion and even closer fits to the experimental data [12].
2.2. The SILVACO simulator
SILVACO is a solid-state process and device simulator that
has the general capabilities for numerical, physically based,
2D and 3D simulations of semiconductor devices [18]. It has
two components: ATHENA, which is a 2D process simulation
framework with software tools for modeling semiconductor
fabrication processes, and ATLAS, which predicts the electri-
cal behavior of semiconductor structures and provides insight
into the internal physical mechanisms associated with device
operation. ATLAS produces outputs in three forms: the run
time output as a guide to the progress of the simulations
running, log files storing summaries of the electrical output
information, and the solution files storing the data related
to the values of the solution variables within the device. The
numerous carrier transport models, the availability of differ-
ent material substrates, and the ability to account for other
physical effects (e.g. surface charges, lattice heating, genera-
tion and recombination) have added greater flexibility to this
device simulator.
Semiconductor device operation is modeled in ATLAS by a
set of one to six coupled, non-linear partial-differential equa-
tions (PDE) [18]. ATLAS provides numerical solutions of these
equations by calculating the values of the unknowns on a
mesh of points within the device. The original, continuous
model (similar to the PNP equations) is converted to a dis-
crete, non-linear algebraic system by an internal discretization
procedure. The sets of PDEs, the mesh and the discretiza-
tion procedure determine the non-linear algebraic problem
to be solved. This is solved using an iterative procedure that
refines successive estimates of the solution. Different solution
procedures (e.g. Gummel, Newton, or block iteration) exhibit
different behavior with respect to convergence, accuracy, effi-
ciency and robustness.
2.3. KcsA ion channel simulations with SILVACO
Based on its structure revealed by X-ray crystallography [2,13],
we have built a KcsA channel model as shown in Fig. 1.
The potassium channel is modeled here as a transmembrane
lumen, surrounded by protein walls and with cylindrical reser-
voirs of potassium and chloride ions at two ends [4–13]. The
channel extends from 10 to 50 Å, with a narrow selectivity fil-
ter of radius 1.5 Å and length 12 Å and a wider segment of
length 23 Å. The selectivity filter extends into the extracellular
space, while the wider segment tapers towards the intracellu-
lar space. Each reservoir at either end has a radius of 40 Å and
a width of around 8 Å.
To replicate the shape of the KcsA channel, the structure is
made of two materials: one to mimic the water continuum that
is conducting, and the other to mimic the non-conducting pro-
tein walls [15,19]. The dielectric constants ε of the conducting
and non-conducting mediums are set as 80 and 2, respectively.
The entire device is constructed from 55 rectangular regions,
which is the maximum limit for ATLAS [18]. Each conduct-
3. computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7 3
Fig. 1 – The model of a KcsA ion channel built in SILVACO.
The channel extends from 10 to 50 Å, with a narrow
selectivity filter of radius 1.5 Å and length 12 Å and a wider
segment of length 23 Å. The selectivity filter extends into
the extracellular space, while the wider segment tapers
towards the intracellular space.
ing region has the capability of being defined with its unique
material properties. To this end, the carrier doping and their
diffusion coefficients are specified in each conducting region
as shown in Fig. 2. This allows us to emulate the fact that there
are considerably fewer carriers in the vestibule of the channel
compared to in the reservoirs. Interestingly, the selectivity fil-
ter hardly has four to five ions at one instant [13], which is
represented as an undoped region in Fig. 2. After the defini-
tion of the device structure, the mesh points are specified to
Fig. 2 – The doping profile of the various conducting
regions in the KcsA model. The extracellular baths have a
symmetric concentration of 100 mM equivalently, while the
selectivity filter is left undoped. The profile to chosen to
represent the realistic scenario in the vestibule of the
channel [13].
denote the locations where solutions are to be determined.
The mesh is defined by a series of horizontal and vertical lines
and the spacing between them. With a maximum limit of only
9600 mesh nodes in ATLAS [18], it is important to use the mesh
lines wisely and in locations which are crucial for the device
behavior. Two electrodes, the source and drain, each of length
20 Å are placed at either ends of the reservoirs for applying a
potential and measuring the electrodiffusion characteristics
of the device.
Despite the fact that ion channels can be modeled as
nanoscale electronic devices as discussed above, there are sev-
eral issues to be addressed in their electrical simulations. The
carriers in electronic devices are electrons and holes, while
those in ion channels are charged ions bound by hydration
shells [10]. The masses and radii of the semiconductor carriers
are significantly small compared to those of ions in channels.
Furthermore, the diffusion coefficient of electrons is around
500 cm2 s−1, while that of K+ ions is around 5 × 10−7 cm2 s−1.
The energy band structure and crystalline structures of solid-
state materials is well known, whereas that of liquids is less
known. On the brighter side, the drift–diffusion PNP theory still
holds for both solid-state devices and ion channels, providing
a simplistic, macroscopic study of the flow of electrons and
ions alike [15–17]. With this basis, we have incorporated many
of the characteristics of ion flow into our channel model. Even
though it is difficult take into account the large mass and radii
of ions, we have adjusted the diffusion coefficients of elec-
trons in each conducting region to describe the slower motion
of ions in a channel’s vestibule [19]. Also, the net carrier doping
and the degree of ionization is specified in a manner to pre-
dict decreased concentrations in the channel’s vestibule and
to obtain realistic current–voltage plots, as shown in Fig. 2.
For this purpose, we have used the fact that the carrier doping
density (per cm3) is given by n = 103
NAVC, where NAV is the
Avogadro’s number and C is the concentration of the solution
(mol/l). As will be demonstrated in the next section, with these
modifications and appropriate mesh definition, it is possible
to obtain realistic simulations results.
3. Results
The solid-state KcsA channel model was simulated using
the PNP theory under various symmetric bath concentrations
and potentials. The discretized PNP equations were solved by
ATLAS using Gummel iteration and with each simulation run-
time of 30 s.
Figs. 3 and 4 show the potential contours along the chan-
nel at a bath concentration of 100 mM and voltages of 100 and
200 mV, respectively. In Fig. 3, for example, a voltage potential
of 100 mV was applied to the drain electrode in the reservoir
at the right side, while the source electrode at the left side
reservoir was kept at ground. The potential drops gradually
along the channel, with most of the significant voltage drop
occurring within the 12 Å length of narrow selectivity filter.
Figs. 5 and 6 plot the electric field contours along the channel
axis at 100 and 200 mV, respectively, and a 100 mM bath con-
centration. The electric field variations can be observed along
the channel, with noticeable changes at either mouths of the
narrow selectivity filter. The entrance and exit of the channel
4. 4 computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7
Fig. 3 – The SILVACO contour profile of the potential
variation along the channel axis with 100 mV applied
across the channel and extracellular bath concentrations of
100 mM.
are made rounded, as any sharp boundaries cause problems
while solving the Poisson’s equation and lead to unwanted
peaks.
Figs. 7 and 8 plot of the electric fields and potentials, respec-
tively, along the channel for varying drain voltages and a bath
concentration of 100 mM. As observed, the simulation pro-
gram takes into account an inherent built-in potential of the
structure, which is around ∼0.575 V in this case. The origin
of this potential is similar to that of Nernst Potential in ion
channels as the SILVACO program considers the same Boltz-
mann energy distribution of carriers [10]. In this case, the bath
concentration is 6 × 1019 cm−3 (or 100 mM equivalently) and
the inside of the channel has an intrinsic concentration of
Fig. 4 – The SILVACO contour profile of the potential
variation along the channel axis with 200 mV applied
across the channel and extracellular bath concentrations of
100 mM.
Fig. 5 – The SILVACO contour profile of the electric field
variation along the channel axis with 100 mV applied
across the channel and extracellular bath concentrations of
100 mM.
1010 cm−3. Plugging this in the formula for the built-in poten-
tial V = (kT/q) ln(Cbath/Cchannel), we get a value of ∼0.575 V. In
Figs. 9 and 10, we plot the electric fields and potentials, respec-
tively, along the channel for a fixed drain voltage of 100 mV
and varying symmetric bath concentrations. As expected, the
built-in potential increases with increasing extracellular con-
centrations.
In an attempt to check the validity of our model, we com-
pare the current–voltage (IV) characteristics from our simula-
tions with those of experiments [20]. Fig. 11 shows the corre-
sponding IV plots of a KcsA channel at two symmetric bath
concentrations of 250 and 500 mM. Using reverse engineer-
ing, the material properties of the solid-state KcsA structure
Fig. 6 – The SILVACO contour profile of the electric field
variation along the channel axis with 200 mV applied
across the channel and extracellular bath concentrations of
100 mM.
5. computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7 5
Fig. 7 – Plots of electric field variation along the channel
axis at varying voltages applied across the channel and
extracellular bath concentrations of 100 mM.
have been adjusted so as to mimic the realistic ion-channel
structure and obtain a good fit between the IV curves. As seen
from Fig. 11, the simulated IV curves closely agree with the
experimental IV curves until 70 mV. Above this voltage, there
is a slight tendency towards saturation in the experimental
curves, whereas the simulated IV curves keep rising almost
linearly. Nevertheless, this degree of agreement between our
simulated results and the experimental IV curves is much bet-
ter than those reported in the previous literature [9].
Next, we consider the effect of surface charges on the
electrical properties of KcsA channels. These surface charges
are known to influence the gating, conductance, and toxin-
binding effects of KcsA ion-channels, and their actual physical
locations are presumed to be in the selectivity filter [21]. Being
negatively charged, these surface charges aid the permeation
of cations and impede the flow of anions through the KscA
channel. Here, we explored the effects of such charges on ion
permeation by placing three positive charges in the selectiv-
ity filter at the interface of water and protein walls (at 40, 44,
Fig. 8 – Plots of potential variation along the channel axis at
varying voltages applied across the channel and
extracellular bath concentrations of 100 mM.
Fig. 9 – Plots of electric field variation along the channel
axis at varying extracellular bath concentrations and an
applied voltage of 100 mV across the channel. In each case,
both the baths are symmetric, having the same
concentration.
and 48 Å in Fig. 2). It is worth mentioning that the surface
charges in our simulations are positive (each QSC = 1014 cm−2)
since the majority carriers used in our model are electrons.
The SILVACO program is versatile in allowing us to incorpo-
rate any fixed charges, interface traps, or even bulk traps at the
semiconductor–insulator interface and observing their effects
on the conduction of a device [18]. Fig. 12 plots the poten-
tial variation along the channel with a bath concentration
of 100 mM and drain voltages of 0 V, 150 mV and 250 mV. In
comparison to its steadily increasing nature in Fig. 7 (with no
charges), the axial potential variation in Fig. 12 (with surface
charges) has a plateau inside the selectivity filter, with three
small humps resulting from the charges at those locations.
The simulated IV curves (with and without charges) are plot-
ted in Fig. 13 for a 250 mM bath concentration. Besides the
Fig. 10 – Plots of potential variation along the channel axis
at varying extracellular bath concentrations and an applied
voltage of 100 mV across the channel. In each case, both the
baths are symmetric, having the same concentration.
6. 6 computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7
Fig. 11 – The current–voltage characteristics of the KcsA
channel model at two different symmetric bath
concentrations (250 and 500 mM). Comparison is made
between the SILVACO simulated plots (—, 250 mM; – – –,
500 mM) and the experimental data (, KcsA: 250 mM; ,
KcsA: 500 mM).
general increase in conductance, there is an added asymme-
try in the linearity of the IV curves (in positive and negative
voltage ranges) by surface charges. As seen in Fig. 13, the
current component due to the majority carriers (electrons) is
enhanced much more compared to that due to the minority
carriers (holes) owing to the attractive and repulsive forces,
respectively, exerted by the surface charges.
4. Discussion
We have demonstrated the possibility of representing a KcsA
channel as a solid-state device, and employing a device simu-
Fig. 12 – Plots of potential variation along the channel axis
at varying voltages applied across the channel, in the
presence of surface charges, and extracellular bath
concentrations of 100 mM. Three pairs of charges (each
QSC = 1014 cm−2) are located inside the selectivity filter at
the interface between the water and protein walls (at 40,
44, and 48 Å in Fig. 2).
Fig. 13 – The simulated current–voltage characteristics of
the KcsA channel model in the presence of surface charges
and at two different symmetric bath concentrations (250
and 500 mM). Besides the increase in conductance, there is
an enhancement in the majority carrier current and
decrease in the minority carrier current. The nature and
amount of surface charges is same as that in Fig. 12.
lator, SILVACO, to simulate its electrical characteristics. With
a goal to mimic the realistic and computationally feasible
scenario inside an ion channel, we created a model with
well-adjusted material parameters and employed SILVACO to
obtain self-consistent solutions of the axial potential and ion
fluxes. The simulated IV curves closely match the available
experimental results, supporting the validity of the model.
Besides giving insight into the general ion permeation
mechanisms in a channel’s vestibule, the simulation results
do open exciting opportunities to extend this work. Addi-
tional features can be incorporated in the model to bridge the
gap between the nature of a semiconductor–insulator and a
water–protein wall interface. In solid-state devices, the inter-
face between a semiconductor and an overlying insulator is
sharp and abrupt, while the dielectric boundary at a channel’s
water–protein wall interface is not so distinctly defined. This
dielectric boundary and its curvature is important in decid-
ing an ion’s potential energy, which varies as 1/εwater in the
baths and as 1/εprotein inside the channel [22]. Even though
the precise value of εprotein is not crucial, it would better our
model to put an additional protein region (εprotein
∼
= 10) at the
dielectric boundary to smoothen the sharp water–protein wall
interface. Also, it is suspected that the dielectric constant of
water decreases inside the channel, and recently Monte Carlo
simulations have shown that lowering its dielectric constant
in a channel’s vestibule alters a channel’s selectivity for dif-
ferent ions [5]. Studies can be performed to investigate the
effects of changing εwater on the channel permeation and its
selectivity for monovalent or divalent ions.
Although our model is based on macroscopic drift–
diffusion computations, they do describe the experimental IV
data surprisingly well. It is, however, tempting to be able to
perform simulations at molecular and atomistic levels (Monte
Carlo and Brownian dynamics) with the computational ease
of PNP programs [19]. In this context, a common platform can
7. computer methods and programs in biomedicine 8 5 ( 2 0 0 7 ) 1–7 7
be built which has the capability of running molecular-level
simulations for a short timeframe, inferring the ion-transport
parameters, and feeding them to the SILVACO program to cal-
culate the ion fluxes within reasonable time. Such a hybrid
model would blend the accurate predictions of molecular-level
simulations with the computationally cheap macroscopic flux
calculations.
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