scholarly journals Dynamic Molecular Switches Drive Negative Memristance Mimicking Synaptic Behavior

2021 ◽  
Author(s):  
christian nijhuis ◽  
Yulong Wang ◽  
Qian Zhang ◽  
Hippolyte Astier ◽  
Cameron Nickle ◽  
...  
Keyword(s):  
Logic Gates ◽  
Von Neumann ◽  
Compact Component ◽  
Memristive Behavior ◽  
Molecular Scale ◽  
Voltage Dependent ◽  
Drive Speed ◽  
Pavlovian Learning ◽  
Conductance States ◽  
Self Learning

To realize molecular scale electrical operations beyond the von Neumann bottleneck, new types of multi-functional switches are needed that mimic self-learning or neuromorphic computing by dynamically toggling between multiple operations that depend on their past. Here we report a molecule that switches from high to low conductance states with massive negative memristive behavior that depends on the drive speed and the number of past switching events. This dynamic molecular switch emulates synaptic behavior and Pavlovian learning and can provide all of the fundamental logic gates because of its time-domain and voltage-dependent plasticity. This multi-functional switch represents molecular scale hardware operable in solid-state devices opening a pathway to dynamic complex electrical operations encoded within a single ultra-compact component.

scholarly journals Modeling of Memristive and Memcapacitive Behaviors in Metal-Oxide Junctions

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
M. G. A. Mohamed ◽  
HyungWon Kim ◽  
Tae-Won Cho
Keyword(s):  
Metal Oxide ◽  
Physical Model ◽  
Tunneling Current ◽  
Behavioral Modeling ◽  
Capacitance Change ◽  
Thin Filaments ◽  
Memristive Behavior ◽  
Modeling Techniques ◽  
Voltage Dependent ◽  
Simulation Results

Memristive behavior has been clearly addressed through growth and shrinkage of thin filaments in metal-oxide junctions. Capacitance change has also been observed, raising the possibility of using them as memcapacitors. Therefore, this paper proves that metal-oxide junctions can behave as a memcapacitor element by analyzing its characteristics and modeling its memristive and memcapacitive behaviors. We develop two behavioral modeling techniques: charge-dependent memcapacitor model and voltage-dependent memcapacitor model. A new physical model for metal-oxide junctions is presented based on conducting filaments variations, and its effect on device capacitance and resistance. In this model, we apply the exponential nature of growth and shrinkage of thin filaments and use Simmons’ tunneling equation to calculate the tunneling current. Simulation results show how the variations of practical device parameters can change the device behavior. They clarify the basic conditions for building a memcapacitor device with negligible change in resistance.

Target-triggered cascade recycling amplification for label-free detection of microRNA and molecular logic operations

2016 ◽  
Vol 52 (2) ◽  
pp. 402-405 ◽  
Author(s):  
Sai Bi ◽  
Jiayan Ye ◽  
Ying Dong ◽  
Haoting Li ◽  
Wei Cao
Keyword(s):  
Logic Gates ◽  
Logic Circuits ◽  
Label Free ◽  
Chemiluminescence Detection ◽  
Molecular Logic ◽  
Label Free Detection ◽  
Molecular Scale ◽  
Ultrahigh Sensitivity ◽  
Recycling Amplification ◽  
Logic Operations

A cascade recycling amplification (CRA) that implements cascade logic circuits with feedback amplification function is developed for label-free chemiluminescence detection of microRNA-122 with an ultrahigh sensitivity of 0.82 fM and excellent specificity, which is applied to construct a series of molecular-scale two-input logic gates by using microRNAs as inputs and CRA products as outputs.

scholarly journals Implicit-OR tiling of deoxyribozymes: Construction of molecular scale OR, NAND and four-input logic gates

2003 ◽  
Vol 68 (4-5) ◽  
pp. 321-326 ◽  
Author(s):  
Milan Stojanovic ◽  
Dragan Nikic ◽  
Darko Stefanovic
Keyword(s):  
Logic Gates ◽  
Molecular Scale ◽  
Complete Set ◽  
Common Substrate

We recently reported the first complete set of molecular-scale logic gates based on deoxyribozymes. Here we report how we tile these logic gates and construct new logic elements: OR, NAND, and the first element with four inputs (i1^i5)V(i2^i6). Tiling of logic gates was achieved through a common substrate used for core deoxyribozyme; degradation of this substrate defines the output. This kind of connection between logic gates is an implicit- OR tiling, because it suffices that one componenet of the network is active for the whole network to give an output of 1.

scholarly journals Luminescent sensors and photonic switches

2001 ◽  
Vol 73 (3) ◽  
pp. 503-511 ◽  
Author(s):  
A. Prasanna de Silva ◽  
David B. Fox ◽  
Thomas S. Moody ◽  
Sheenagh M. Weir
Keyword(s):  
Small Molecules ◽  
Excited States ◽  
Logic Gates ◽  
Xor Gate ◽  
Luminescent Sensors ◽  
Photonic Switches ◽  
Multiple Receptors ◽  
Molecular Scale ◽  
First Time ◽  
Internal Charge Transfer

The principles of photochemistry continue to fuel progress in luminescent sensors and photonic switches. Examples of sensors based on photoinduced electron transfer (PET) are discussed, including those which form the basis of successful systems used in physiology and medicine. More complex formats usually involve multiple receptors. One progression takes us to lanthanide complexes enabled with sensory capabilities. Another path takes us to molecular-scale implementation of logic gates such as AND and INHIBIT. Such luminescent switches can be enriched by combination with nonluminescent cousins. The latter are based on internal charge-transfer excited states (ICT). An example of rudimentary arithmetic at the molecular scale is presented by running a luminescent AND gate in parallel with a nonluminescent XOR gate. Thus, small molecules can process small numbers for the first time outside of our brains.

scholarly journals The Role of Voltage-Dependent Anion Channel in Mitochondrial Dysfunction and Human Disease

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1737
Author(s):  
Joyce T. Varughese ◽  
Susan K. Buchanan ◽  
Ashley S. Pitt
Keyword(s):  
Physiological Role ◽  
Anion Channel ◽  
Calcium Flux ◽  
Voltage Dependent Anion Channel ◽  
X Ray Crystallography ◽  
Mitochondrial Regulation ◽  
Interaction Partners ◽  
Voltage Dependent ◽  
Conductance States

The voltage-dependent anion channel (VDAC) is a β-barrel membrane protein located in the outer mitochondrial membrane (OMM). VDAC has two conductance states: an open anion selective state, and a closed and slightly cation-selective state. VDAC conductance states play major roles in regulating permeability of ATP/ADP, regulation of calcium homeostasis, calcium flux within ER-mitochondria contact sites, and apoptotic signaling events. Three reported structures of VDAC provide information on the VDAC open state via X-ray crystallography and nuclear magnetic resonance (NMR). Together, these structures provide insight on how VDAC aids metabolite transport. The interaction partners of VDAC, together with the permeability of the pore, affect the molecular pathology of diseases including Parkinson’s disease (PD), Friedreich’s ataxia (FA), lupus, and cancer. To fully address the molecular role of VDAC in disease pathology, major questions must be answered on the structural conformers of VDAC. For example, further information is needed on the structure of the closed state, how binding partners or membrane potential could lead to the open/closed states, the function and mobility of the N-terminal α-helical domain of VDAC, and the physiological role of VDAC oligomers. This review covers our current understanding of the various states of VDAC, VDAC interaction partners, and the roles they play in mitochondrial regulation pertaining to human diseases.

scholarly journals Rediscovering Majority Logic in the Post-CMOS Era: A Perspective from In-Memory Computing

2020 ◽  
Vol 10 (3) ◽  
pp. 28
Author(s):  
John Reuben
Keyword(s):  
Integrated Circuits ◽  
Logic Gates ◽  
Expressive Power ◽  
Boolean Logic ◽  
Majority Gate ◽  
Von Neumann ◽  
Majority Logic ◽  
Memory Array ◽  
Memory Wall ◽  
Parallel Prefix

As we approach the end of Moore’s law, many alternative devices are being explored to satisfy the performance requirements of modern integrated circuits. At the same time, the movement of data between processing and memory units in contemporary computing systems (‘von Neumann bottleneck’ or ‘memory wall’) necessitates a paradigm shift in the way data is processed. Emerging resistance switching memories (memristors) show promising signs to overcome the ‘memory wall’ by enabling computation in the memory array. Majority logic is a type of Boolean logic which has been found to be an efficient logic primitive due to its expressive power. In this review, the efficiency of majority logic is analyzed from the perspective of in-memory computing. Recently reported methods to implement majority gate in Resistive RAM array are reviewed and compared. Conventional CMOS implementation accommodated heterogeneity of logic gates (NAND, NOR, XOR) while in-memory implementation usually accommodates homogeneity of gates (only IMPLY or only NAND or only MAJORITY). In view of this, memristive logic families which can implement MAJORITY gate and NOT (to make it functionally complete) are to be favored for in-memory computing. One-bit full adders implemented in memory array using different logic primitives are compared and the efficiency of majority-based implementation is underscored. To investigate if the efficiency of majority-based implementation extends to n-bit adders, eight-bit adders implemented in memory array using different logic primitives are compared. Parallel-prefix adders implemented in majority logic can reduce latency of in-memory adders by 50–70% when compared to IMPLY, NAND, NOR and other similar logic primitives.

Open-channel subconductance state of K+ channel from cardiac sarcoplasmic reticulum

1990 ◽  
Vol 258 (1) ◽  
pp. H159-H164 ◽  
Author(s):  
J. A. Hill ◽  
R. Coronado ◽  
H. C. Strauss
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Open Channel ◽  
State Transitions ◽  
K Channel ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Reaction Rate Constants ◽  
Binary Model ◽  
Voltage Dependent ◽  
Conductance States ◽  
Open States

We have characterized the K+ channel of canine cardiac sarcoplasmic reticulum in terms of its gating kinetics and conductance states. We demonstrate that the open channel dwells in two states, O1 and O2, where O1 is a true subconductance state of O2. The two open states are linked with a closed state by a cyclic gating scheme. Under certain circumstances, however, important information can be derived using a binary model. Each open state separately exhibited an ohmic current-voltage relation with unitary conductance values of 105 (O1) and 189 (O2) pS in 0.1 M K+. Gating between closed and open states was weakly voltage dependent, and we derive reaction rate constants for the state transitions. Finally, we postulate three models to explain the existence of a subconductance state (blockade, stenosis, flutter). We argue that a flutter model best accounts for our observations of O1.

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