Single‐wall and multi‐wall carbon nanotubes promote rice root growth by eliciting the similar molecular pathways and epigenetic regulation

Organisms are constantly exposed to environmental stimuli and have evolved mechanisms of protection and adaptation. Various effects of nanoparticles (NPs) on crops have been described and some results confirm that NPs could enhance plant growth at the physiological and genetic levels. This study comparatively analysed the effect of carbon nanotubes (CNTs) on rice growth. The results showed that single‐wall CNTs were located in the intercellular space while multi‐wall CNTs penetrated cell walls in roots. CNTs could promote rice root growth through the regulation of expression of the root growth related genes and elevated global histone acetylation in rice root meristem zones. These responses were returned to normal levels after CNTs were removed from medium. CNTs caused the similar histone acetylation and methylation statuses across the local promoter region of the Cullin‐RING ligases 1 (CRL1) gene and increased micrococcal nuclease accessibility of this region, which enhanced this gene expression. The authors results suggested that CNTs could cause plant responses at the cellular, genetic, and epigenetic levels and these responses were independent on interaction modes between root cells and CNTs.Inspec keywords: crops, multi‐wall carbon nanotubes, single‐wall carbon nanotubes, nanobiotechnology, cellular biophysics, genetics, enzymes, biochemistry, molecular biophysicsOther keywords: single‐wall carbon nanotubes, multiwall carbon nanotubes, rice root growth, molecular pathways, epigenetic regulation, environmental stimuli, crops, intercellular space, cell walls, global histone acetylation, rice root meristem zones, histone acetylation, methylation statuses, local promoter region, CRL1 gene, micrococcal nuclease accessibility, root growth related gene expression, plant responses, cellular levels, epigenetic levels, genetic levels, interaction modes, C     

Experimental and theoretical investigation of sensing parameters in carbon nanotube‐based DNA sensor

Nowadays, sensitive biosensors with high selectivity, lower costs and short response time are required for detection of DNA. The most preferred materials in DNA sensor designing are nanomaterials such as carbon and Au nanoparticles, because of their very high surface area and biocompatibility which lead to performance and sensitivity improvements in DNA sensors. Carbon nanomaterials such as carbon nanotubes (CNTs) can be considered as a suitable DNA sensor platform due to their high surface‐to‐volume ratio, favourable electronic properties and fast electron transfer rate. Therefore, in this study, the CNTs which are synthesised by pulsed AC arc discharge method on a high‐density polyethylene substrate are used as conducting channels in a chemiresistor for the electrochemical detection of double stranded DNA. Moreover, the response of the proposed sensor is investigated experimentally and analytically in different temperatures, which confirm good agreement between the presented model and experimental data.Inspec keywords: electrochemical sensors, polymers, arcs (electric), biological techniques, nanosensors, carbon nanotubes, DNAOther keywords: C, chemiresistor, double stranded DNA detection, CNT, electronic properties, surface‐to‐volume ratio, nanoparticles, biosensors, electrochemical detection, high‐density polyethylene substrate, pulsed AC arc discharge method, electron transfer rate, carbon nanomaterials, carbon nanotube‐based DNA sensor     

Bogdanov–Takens bifurcation in a neutral BAM neural networks model with delays

In this study, the authors first discuss the existence of Bogdanov–Takens and triple zero singularity of a five neurons neutral bidirectional associative memory neural networks model with two delays. Then, by utilising the centre manifold reduction and choosing suitable bifurcation parameters, the second‐order and the third‐order normal forms of the Bogdanov–Takens bifurcation for the system are obtained. Finally, the obtained normal form and numerical simulations show some interesting phenomena such as the existence of a stable fixed point, a pair of stable non‐trivial equilibria, a stable limit cycles, heteroclinic orbits, homoclinic orbits, coexistence of two stable non‐trivial equilibria and a stable limit cycles in the neighbourhood of the Bogdanov–Takens bifurcation critical point.Inspec keywords: neurophysiology, neural nets, bifurcation, delays, critical pointsOther keywords: Bogdanov‐Takens bifurcation critical point, neutral BAM neural networks, bidirectional associative memory, delays, triple zero singularity, neurons, centre manifold reduction, bifurcation parameters, second‐order normal forms, third‐order normal forms, numerical simulations, stable fixed point, stable nontrivial equilibria, stable limit cycles, heteroclinic orbits, homoclinic orbits     

Time‐invariant biological networks with feedback loops: structural equation models and structural identifiability

Quantitative analyses of biological networks such as key biological parameter estimation necessarily call for the use of graphical models. While biological networks with feedback loops are common in reality, the development of graphical model methods and tools that are capable of dealing with feedback loops is still in its infancy. Particularly, inadequate attention has been paid to the parameter identifiability problem for biological networks with feedback loops such that unreliable or even misleading parameter estimates may be obtained. In this study, the structural identifiability analysis problem of time‐invariant linear structural equation models (SEMs) with feedback loops is addressed, resulting in a general and efficient solution. The key idea is to combine Mason''s gain with Wright''s path coefficient method to generate identifiability equations, from which identifiability matrices are then derived to examine the structural identifiability of every single unknown parameter. The proposed method does not involve symbolic or expensive numerical computations, and is applicable to a broad range of time‐invariant linear SEMs with or without explicit latent variables, presenting a remarkable breakthrough in terms of generality. Finally, a subnetwork structure of the C. elegans neural network is used to illustrate the application of the authors’ method in practice.Inspec keywords: matrix algebra, least squares approximations, statistical analysis, parameter estimation, biologyOther keywords: structural identifiability analysis problem, time‐invariant linear structural equation models, feedback loops, identifiability equations, time‐invariant linear SEMs, time‐invariant biological networks, graphical model methods, parameter identifiability problem, biological parameter estimation, subnetwork structure, C. elegans neural network     

In‐vitro toxicity of carbon nanotube/polylysine colloids to colon cancer cells

Single‐walled carbon nanotubes (SWCNTs) are thoroughly purified and dispersed in an aqueous solution of high molecular weight poly‐L‐lysine (pLlys). Human intestinal epithelial Caco‐2/TC7 cells are incubated with the SWCNT dispersions in pLlys, and their effects on cell viability are studied by image flow cytometry. No significant changes are observed in the cell culture wells up to pLlys concentrations of 10 μg ml⁻¹. However, high mortality is detected at pLlys concentrations of 100 μg ml⁻¹. The presence of oxygen‐free SWCNTs does not modify the effects of pLlys on cell cultures at any of the tested concentrations (≤1 μg ml⁻¹). In addition, SWCNTs having an 8 wt.% of surface oxygen are tested with identical results. Thus, purified SWCNTs, even bearing oxygen functional groups, act as inert particles in the cell culture medium. This result supports the applicability of SWCNTs as carriers in pharmacological formulations against digestive tract diseases.Inspec keywords: single‐wall carbon nanotubes, cellular biophysics, molecular weight, filled polymers, biochemistry, cancer, colloidsOther keywords: surface oxygen, mortality, cell culture wells, image flow cytometry, human intestinal epithelial Caco‐2/TC7 cells, molecular weight, aqueous solution, single walled carbon nanotubes, colon cancer cells, carbon nanotube‐polylysine colloids, toxicity     

Effect of external periodic signals and electromagnetic radiation on autaptic regulation of neuronal firing

An improved Hindmarsh–Rose (HR) neuron model, where the memristor is a bridge between membrane potential and magnetic flux, can be used to investigate the effect of periodic signals on autaptic regulation of neurons under electromagnetic radiation. Based on the improved HR model driven by periodic high–low‐frequency current and electromagnetic radiation, the responses of electrical autaptic regulation with diverse high–low‐frequency signals are investigated using bifurcation analysis. It is found that the electrical modes of neurons are determined by the selecting parameters of both periodic high and low‐frequency current and electromagnetic radiation, and the Hamiltonian energy depends on the neuronal firing modes. The effects of Gaussian white noise on the membrane potential are discussed using numerical simulations. It is demonstrated that external high–low‐frequency stimulus plays a significant role in the autaptic regulation of neural firing mode, and the electrical mode of neurons can be affected by the angular frequency of both high–low‐frequency forcing current and electromagnetic radiation. The mechanism of neuronal firing regulated by high–low‐frequency signal and electromagnetic radiation discussed here could be applied to research neuronal networks and synchronisation modes.Inspec keywords: bioelectric potentials, neural nets, bifurcation, synchronisation, memristors, neurophysiology, numerical analysis, white noiseOther keywords: synchronisation modes, external periodic signals, electromagnetic radiation, improved Hindmarsh–Rose neuron model, membrane potential, periodic high–low‐frequency current, electrical autaptic regulation, diverse high–low‐frequency signals, neuronal firing modes, external high–low‐frequency stimulus, high–low‐frequency forcing current, high–low‐frequency signal, research neuronal networks     

Preparation and characterisation of CNF/MWCNT carbon aerogel as efficient adsorbents

In recent years, carbon aerogels have attracted much attention in basic research and as potential applications in many fields. Herein, the authors report a novel approach using bamboo powder as raw material to fabricate cellulose nanofibers (CNFs)/multi‐walled carbon nanotubes (MWCNTs) carbon aerogels by a simple dipping and carbonisation process. The developed material exhibits many exciting properties including low density (0.056 g cm⁻³), high porosity (95%), efficient capability for separation of oily droplets from water, and high adsorption capacity for a variety of oils and organic solvents by up to 110 times its own weight. Furthermore, the CNF/MWCNT carbon aerogels (CMCA) can be recycled many times by distillation and combustion, satisfying the requirements of practical oil‐water separation. Taken together with its economical, environmentally benign manufacturing process, sustainability of the precursor and versatility of material, the CMCA developed in this study will be a promising candidate for addressing the problems arising from the spills of oily compounds.Inspec keywords: aerogels, adsorption, nanofibres, filled polymers, nanocomposites, multi‐wall carbon nanotubes, porosity, drops, distillation, combustion, nanofabrication, polymer fibresOther keywords: CNF‐MWCNT carbon aerogel, adsorbents, bamboo powder, cellulose nanofibers, multiwalled carbon nanotubes, dipping, carbonisation, density, porosity, oily droplets, adsorption capacity, organic solvents, distillation, combustion, practical oil‐water separation, manufacturing process, sustainability, C     

In silico discovery of significant pathways in colorectal cancer metastasis using a two‐stage optimisation approach

Accurate and reliable modelling of protein–protein interaction networks for complex diseases such as colorectal cancer can help better understand mechanism of diseases and potentially discover new drugs. Different machine learning methods such as empirical mode decomposition combined with least square support vector machine, and discrete Fourier transform have been widely utilised as a classifier and for automatic discovery of biomarkers for the diagnosis of the disease. The existing methods are, however, less efficient as they tend to ignore interaction with the classifier. In this study, the authors propose a two‐stage optimisation approach to effectively select biomarkers and discover interactions among them. At the first stage, particle swarm optimisation (PSO) and differential evolution (DE) are used to optimise parameters of support vector machine recursive feature elimination algorithm, and dynamic Bayesian network is then used to predict temporal relationship between biomarkers across two time points. Results show that 18 and 25 biomarkers selected by PSO and DE‐based approach, respectively, yields the same accuracy of 97.3% and F1‐score of 97.7 and 97.6%, respectively. The stratified analysis reveals that Alpha‐2‐HS‐glycoprotein was a dominant hub gene with multiple interactions to other genes including Fibrinogen alpha chain, which is also a potential biomarker for colorectal cancer.Inspec keywords: cancer, proteins, particle swarm optimisation, evolutionary computation, support vector machines, recursive functions, Bayes methods, genetics, molecular biophysics, medical computingOther keywords: colorectal cancer metastasis, two‐stage optimisation approach, protein–protein interaction networks, biomarkers, particle swarm optimisation, differential evolution, support vector machine recursive feature elimination, dynamic Bayesian network, stratified analysis, Alpha‐2‐HS‐glycoprotein, hub gene, Fibrinogen alpha chain     

Synthesis and characterization of MWCNT/TiO2 /Au nanocomposite for photocatalytic and antimicrobial activity.

A novel combination of titanium oxide (TiO₂)/gold (Au)/multiwalled carbon nanotubes (MWCNTs) nanocomposite (NC) was synthesised by sol– gel method. MWCNT functionalisation by modified Hummers method. TiO₂ /Au nanoparticles (NPs) were synthesised by biological method using Terminalia chebula bark extract. MWCNT/TiO₂ /Au NC samples were characterised by X‐ray diffraction, ultraviolet–visible–diffuse reflectance spectra, microRaman, scanning electron microscopy and high‐resolution‐transmission electron microscopy analyses. The photocatalytic performance of the obtained for NC toward the decomposition of congo‐red and the antimicrobial activity for inhibition of Gram positive (Bacillus subtilis, Streptococcus pneumonia and Staphylococcus aureus), Gram negative (Shigella dysenderiae, Proteus vulgaris and Klebsiella pneumonia) and fungal strains have been evaluated and the results are compared with positive control ampicillin. The metal and metal–oxide NPs have a lower sorption capacity. The herbicidal bond to the tested CNTs by the combination of electron donor–acceptor interactions and hydrogen bonds. In particular, the dispersion of NC and control of sodium borohydride, it has more efficient effect on the photodegradation and antibacterial activity of positive control of ampicillin. The NC material has exhibited maximum photodegradation and antibacterial activity results of zone of inhibition when compared with control samples.Inspec keywords: nanocomposites, nanoparticles, titanium compounds, gold, multi‐wall carbon nanotubes, nanofabrication, sol‐gel processing, catalysis, photodissociation, antibacterial activity, microorganisms, X‐ray diffraction, reflectivity, Raman spectra, ultraviolet spectra, visible spectra, hydrogen bonds, scanning electron microscopy, transmission electron microscopy, dyes, sorption, nanobiotechnologyOther keywords: titanium oxide‐gold‐multiwalled carbon nanotubes nanocomposite, sol‐gel method, photocatalytic activity, antimicrobial activity, MWCNT functionalisation, modified Hummers method, nanoparticles, biological method, Terminalia chebula bark extract, X‐ray diffraction, ultraviolet‐visible‐diffuse reflectance spectra, microRaman spectra, scanning electron microscopy, high‐resolution‐transmission electron microscopy, congo‐red decomposition, Gram positive bacteria, Bacillus subtilis, Streptococcus pneumonia, Staphylococcus aureus, Shigella dysenderiae, Proteus vulgaris, Klebsiella pneumonia, fungal strains, Gram negative bacteria, sorption capacity, herbicidal bond, electron donor‐acceptor interactions, hydrogen bonds, sodium borohydride, photodegradation, metal‐oxide nanoparticles, C‐TiO₂ ‐Au     

Inferring non‐synonymous single‐nucleotide polymorphisms‐disease associations via integration of multiple similarity networks

Detecting associations between human genetic variants and their phenotypic effects is a significant problem in understanding genetic bases of human‐inherited diseases. The focus is on a typical type of genetic variants called non‐synonymous single nucleotide polymorphisms (nsSNPs), whose occurrence may potentially alter the structures of proteins, affecting functions of proteins, and thereby causing diseases. Most of the existing methods predict associations between nsSNPs and diseases based on features derived from only protein sequence and/or structure information, and give no information about which specific disease an nsSNP is associated with. To cope with these problems, the identification of nsSNPs that are associated with a specific disease from a set of candidate nsSNPs as a binary classification problem has been formulated. A new approach has been adopted for predicting associations between nsSNPs and diseases based on multiple nsSNP similarity networks and disease phenotype similarity networks. With a series of comprehensive validation experiments, it has been demonstrated that the proposed method is effective in both recovering the nsSNP‐disease associations and inferring suspect disease‐associated nsSNPs for both diseases with known genetic bases and diseases of unknown genetic bases.Inspec keywords: diseases, genetics, polymorphism, proteinsOther keywords: nonsynonymous single‐nucleotide polymorphisms, disease associations, multiple similarity network integration, human genetic variants, phenotypic effects, human‐inherited diseases, nonsynonymous single nucleotide polymorphisms, proteins, protein sequence, structure information, candidate nsSNP, binary classification problem, disease phenotype similarity networks, unknown genetic bases     

Facile synthesis of gold nanoparticles using carbon dots for electrochemical detection of neurotransmitter,dopamine in human serum and as a chemocatalyst for nitroaromatic reduction

Herein, the authors reported a carbon dots mediated synthesis of gold nanoparticles (AuNPs) at room temperature. Transmission electron microscopy revealed that the AuNPs are spherical in shape with a size of 10 nm. As‐prepared AuNPs was immobilised on carbon paste electrode and subjected to electrochemical sensing of an important neurotransmitter dopamine. Differential pulse voltammetry studies revealed sensitive and selective determination of dopamine in the presence of commonly interfering ascorbic acid and uric acid. The linear detection range was 10–600 μM and the limit of detection was 0.7 ± 0.18 μM. The practical application was demonstrated by measuring dopamine in human blood serum and urine samples. The catalytic activity of AuNPs was evaluated by sodium borohydride mediated reduction of nitroaromatic compounds. The reduction kinetics was found to be pseudo‐first‐order kinetics. All the tested nitroaromatics reduced to corresponding amines in <10 min.Inspec keywords: voltammetry (chemical analysis), electrochemical sensors, biosensors, nanosensors, reduction (chemical), organic compounds, nanofabrication, gold, catalysis, transmission electron microscopy, electrochemical electrodes, blood, nanoparticles, carbon, chemical variables measurement, catalysts, particle sizeOther keywords: nitroaromatic compounds, reduction kinetics, gold nanoparticles, chemocatalyst, nitroaromatic reduction, carbon dots mediated synthesis, room temperature, transmission electron microscopy, carbon paste electrode, electrochemical sensing, ascorbic acid, uric acid, linear detection range, human blood serum, urine samples, sodium borohydride mediated reduction, neurotransmitter dopamine, differential pulse voltammetry, catalytic activity, pseudofirst‐order kinetics, amines, temperature 293 K to 298 K, C‐Au     

Non‐fragile reliable control synthesis of the sugarcane borer

This study considers the problem of non‐fragile reliable control synthesis for mathematical model of interaction between the sugarcane borer (Diatraea saccharalis) and its egg parasitoid Trichogramma galloi. In particular, the control could be substituted by periodic releases of a small population of natural enemies and hence it is important to propose the time‐varying controller in sugarcane borer. The main aim of this study is to design a state feedback non‐fragile (time‐varying) reliable controller such that the states of the sugarcane borer system reach the equilibrium point within the desired period. A novel approach is proposed to deal with the uncertain matrices which appear in non‐fragile reliable control. Finally, simulations based on sugarcane borer systems are conducted to illustrate the advantages and effectiveness of the proposed design technique. The result reveals that the proposed non‐fragile control provides good performance in spite of periodic releases of a small population of natural enemies occurs.Inspec keywords: microorganisms, plant diseases, biology computing, state feedback, biocontrol, control system synthesisOther keywords: nonfragile reliable control synthesis, sugarcane borer, mathematical model, Diatraea saccharalis, egg parasitoid, Trichogramma galloi, periodic releases, natural enemies, state feedback nonfragile time‐varying reliable controller, equilibrium point, design technique     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C     

Architecture‐dependent robustness in a class of multiple positive feedback loops

Many types of multiple positive feedbacks with each having potentials to generate bistability exist extensively in natural, raising the question of why a particular architecture is present in a cell. In this study, the authors investigate multiple positive feedback loops across three classes: one‐loop class, two‐loop class and three‐loop class, where each class is composed of double positive feedback loop (DPFL) or double negative feedback loop (DNFL) or both. Through large‐scale sampling and robustness analysis, the authors find that for a given class, the homogeneous DPFL circuit (i.e. the coupled circuit that is composed of only DPFLs) is more robust than all the other circuits in generating bistable behaviour. In addition, stochastic simulation shows that the low stable state is more robust than the high stable state in homogeneous DPFL whereas the high‐stable state is more robust than the low‐stable state in homogeneous DNFL circuits. It was argued that this investigation provides insight into the relationship between robustness and network architecture.Inspec keywords: cellular biophysics, feedback, sampling methods, stochastic processesOther keywords: network architecture, low stable state, stochastic simulation, bistable behaviour, homogeneous DPFL circuit, robustness analysis, large‐scale sampling, DNFL, double negative feedback loop, double positive feedback loop, three‐loop class, two‐loop class, one‐loop class, cell architecture, bistability, multiple positive feedback loops, architecture‐dependent robustness     

Functional tunability of biological circuits from additional toggle switches

In many complex regulatory networks with interlinked feedback loops, the simple core circuits are sufficient to achieve the specific biological functions of the whole networks, naturally raising a question: what is the role of the additional feedback loops. By investigating the effect of an additional toggle switch on the auto‐activation circuit responsible for competent switch in Bacillus subtilits and on the activator–repressor circuit responsible for cell cycle in Xenopus embryonic, the authors show that the additional toggle switch can elaborate the dynamical behaviour of both circuits. Specifically, the additional toggle switch in B. subtilits does not significantly affect the saturation level of the competent state but can tune the activation threshold (i.e. the minimal stimulus required to switch the system from the non‐competent state to the competent state). For the activator–repressor circuit in X. embryonic cell cycle, the additional toggle switch can tune the oscillation frequency but does not change the oscillation amplitude. The proposed detailed results not only provide guidelines to the engineering of synthetic genetic circuits, but also imply a significant fact that additional toggle switches in a complex network are not really redundant but play a role of tuning network functions.Inspec keywords: biochemistry, cellular biophysics, microorganismsOther keywords: functional tunability, biological circuits, toggle switches, complex regulatory networks, interlinked feedback loops, Bacillus subtilits, autoactivation circuit, activator‐repressor circuit, Xenopus embryonic     

Two faces of competition: target‐mediated reverse signalling in microRNA and mitogen‐activated protein kinase regulatory networks

Biomolecular regulatory networks are organised around hubs, which can interact with a large number of targets. These targets compete with each other for access to their common hubs, but whether the effect of this competition would be significant in magnitude and in function is not clear. In this review, the authors discuss recent in vivo studies that analysed the system level retroactive effects induced by target competition in microRNA and mitogen‐activated protein kinase regulatory networks. The results of these studies suggest that downstream targets can regulate the overall state of their upstream regulators, and thus cannot be ignored in analysing biomolecular networks.Inspec keywords: reviews, RNA, molecular biophysics, enzymesOther keywords: target‐mediated reverse signalling, mitogen‐activated protein kinase regulatory networks, biomolecular regulatory networks, microRNA regulatory networks, review, in vivo study     

Small RNA‐mediated switch‐like regulation in bacterial quorum sensing

Quorum sensing (QS) is a signalling mechanism by which bacteria produce, release and then detect and respond to changes in their density and biosignals called autoinducers (AIs). There are multiple feedback loops in the QS system of Vibrio harveyi. However, how these feedback loops function to control signal processing remains unclear. In this study, the authors present a computational model for the switch‐like regulation of signal transduction by small regulatory RNA‐mediated QS based on intertwined network involving AIs, LuxO, LuxU, Qrr sRNAs and LuxR. In agreement with experimental observations, the model suggests that different feedbacks play critical roles in the switch‐like regulation. The authors results reveal that V. harveyi uses multiple feedbacks to precisely control signal transduction.Inspec keywords: biocommunications, biocontrol, biology computing, cellular biophysics, physiological models, RNAOther keywords: RNA‐mediated switch‐like regulation, bacterial quorum sensing, signaling mechanism, autoinducers, Vibrio harveyi, feedback loops function, signal processing control, switch‐like regulation     

Controllability and observability analysis of basal ganglia model and feedback linearisation control

Deep brain stimulation (DBS) is a clinical remedy to control tremor in Parkinson''s disease. In DBS, one of the two main areas of basal ganglia (BG) is stimulated. This stimulation is produced with no feedback of the tremor and often causes a wide range of unpleasant side effects. Using a feedback signal from tremor, the stimulatory signal can be reduced or terminated to avoid extra stimulation and as a result decrease the side effects. To design a closed‐loop controller for the non‐linear BG model, a complete study of controllability and observability of this system is presented in this study. This study shows that the BG model is controllable and observable. The authors also propose the idea of stimulating the two BG areas simultaneously. A two‐part controller is then designed: a feedback linearisation controller for subthalamic nucleus stimulation and a partial state feedback controller for globus pallidus internal stimulation. The controllers are designed to decrease three indicators: the hand tremor, the level of delivered stimulation signal in disease condition, and the ratio of the level of delivered stimulation signal in health condition to disease condition. Considering these three indicators, the simulation results show satisfactory performance.Inspec keywords: feedback, brain, neurophysiology, diseases, medical control systems, closed loop systems, controllers, linearisation techniques, bioelectric phenomenaOther keywords: controllability analysis, observability analysis, basal ganglia model, feedback linearisation control, deep brain stimulation, clinical remedy, tremor control, Parkinson''s disease, feedback signal, closed‐loop controller, nonlinear BG model, feedback linearisation controller, two‐part controller, subthalamic nucleus stimulation, partial state feedback controller, globus pallidus internal stimulation, disease condition, delivered stimulation signal