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1.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 3973-3976, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018870

RESUMO

Low electrode-skin impedance can be achieved if the interface has an electrolytic medium that allows the movement of ions across the interface. Maintaining good physical contact of the sensor with the skin is imperative. We propose a novel hydrophilic conductive sponge interface that encapsulates both of these fundamental concepts into an effective physical realization. Our implementation uses a hydrophilic polyurethane prepolymer doped with conductive carbon nanofibers and cured to form a flexible sponge material that conforms to uneven surfaces, for instance, on parts of the scalp with hair. Our results show that our sponges are able to stay in a hydrated state with a low electrode-skin impedance of around 5kΩ for more than 20 hours. The novelty in our conductive sponges also lies in their versatility: the carbon nanofibers make the electrode effective even when the electrode dries up. The sensors remain conductive with a skin impedance on the order of 20kΩ when dry, which is substantially lower than typical impedance of dry electrodes, and are able to extract alpha wave EEG activity in both wet and dry conditions.


Assuntos
Eletroencefalografia , Condutividade Elétrica , Impedância Elétrica , Eletrodos , Desenho de Equipamento
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4105-4108, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018901

RESUMO

The aim of this paper is to experimentally assess the capacity of radio-frequency flexible sensors to localize a dielectric object inside a fluid, which could be used as a non contact sensor detected to the detection or the monitoring a local modification of a tissue, such as a tumor or a lesion. The used sensor is an MRI-like antenna, which consists in a flat, flexible and low cost multi-turn split resonator (MTLR), which features a geometrically pre-determined resonance frequency. The MTLR is used here as a transmit and receive sensor monitored by a distant loop coil. The complex impedance changes observed at the ends of the monitoring coil is known to be linked to the dielectric properties of the resonator environment. If a dielectric object is placed close to the resonator, the complex impedance is altered. In this work, an experimental set up is used to assess the relevance of such a measurement scheme to detect the presence of a dielectric inclusion embedded in another dielectric medium. The setup includes a spherical object of 1.5 cm diameter filled with various NaCl solutions moved vertically inside a tank filled with deionized water by means of a three axis robotic arm, to create an electrical conductivity contrast between the inclusion and the media, and three 2 cm diameter MTLR sensors featuring 30, 47 and 70 MHz resonance frequencies, respectively. The sensors are operated through the use of monitoring coils connected to a network analyzer, and measurements are carried out at each position of the spherical object. The resulting sensor responses are plotted and used for the assessment of sensor performances. In addition, a method to combine the multi-frequency data provided by the three different sensors is proposed. Two different metrics regarding the spatial resolution (SR) and the peak signal to noise ratio (PSNR) are computed to characterize the single sensor performances, as well as the enhancement provided by the proposed multi-frequency approach.


Assuntos
Ondas de Rádio , Água , Condutividade Elétrica , Impedância Elétrica , Razão Sinal-Ruído
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4373-4376, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018964

RESUMO

A new multi-material polymer fiber electrode has been developed for smart clothing applications. The conductive fiber is optimized for bipotential measurements such as surface electromyogram (sEMG) and electrocardiogram (ECG). The main benefit of this fiber is its flexibility and being a dry and non-obtrusive electrode. It can be directly integrated into a garment to make a smart textile for real time biopoten-tial monitoring. A customized wireless electronic system has been developed to acquire electrophysiological signal from the fiber. The receiver base station is connected to a PC host running Matlab. The multi-material polymer fiber electrode recording setting were first optimized in length and inter-electrode distance by recording different sEMG signals. The typical sEMG signal to noise ratio ranges from 19.1 dB to 33.9 dB depending on the geometry. These value are comparable with those obtained with Ag/AgCl electrodes and dry electrode-base commercial system such as Delsys Trigno. The frequency domain analysis obtained from the power spectral density reveals that the new flexible fiber-electrode enables high sEMG signals recording quality while being suitable for integration in smart clothing fabric. A muscle fatigue analysis and ECG recording are also presented in this study. The multi-material polymer fiber electrodes demonstrate a viable solution for sEMG and ECG data acquisition.


Assuntos
Polímeros , Têxteis , Fibras na Dieta , Condutividade Elétrica , Eletrodos
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4402-4405, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018971

RESUMO

This paper describes a research collaboration with Studio 1 Labs to provide the characterization for a novel smart baby monitoring device which includes conductive fabrics. The electrical characterization of the conductive fabrics is important for designing a bedsheet that can adequately be sensitive to physiological movement. Electrical impedance spectroscopy (EIS) has been performed using the Metrohm Autolab potentiostat on a two-fabric interface. For an increase in applied weight, there was an overall decrease in impedance shown both in its real and imaginary components. A simple RC circuit model could be used to describe the system. A test bedsheet was made from a 3x3 conductive fabric matrix stitched into a cotton sheet. Conversely, an increase in resistance was observed from an increase in applied weights at the intersection points of the bedsheet. The following characterization provided useful insight into the future design of the smart bedsheet.


Assuntos
Espectroscopia Dielétrica , Têxteis , Condutividade Elétrica , Impedância Elétrica
5.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4506-4509, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018995

RESUMO

Smart devices are quickly becoming ubiquitous with the rise of portable biosensors and the internet of things. There exists particular interest in enhancing common objects to have smart capabilities and finding inexpensive solutions for diagnostic tools. One such example is transforming paper items into interactive devices and point-of-care analytic products. Due to the lightweight, flexible, and cost-efficient qualities of paper, unobtrusively powering these devices remains an outstanding problem. In this paper, we demonstrate an electrostatic human-touch powered energy harvesting system, integrated with flexible painted conductive electrodes on paper. This system harvests 8.5 nJ of energy and reaches a voltage of 1.3 V on a 10 nF energy storage capacitor. This technology not only provides a method of powering paper-based products with routine human gestures but can also detect human touch for input communication to sensors.


Assuntos
Eletrônica , Condutividade Elétrica , Eletrodos , Humanos , Fenômenos Físicos , Eletricidade Estática
6.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4555-4558, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019007

RESUMO

Textile-based strain sensors combine wearability with strain sensing functionality by using only the tensile and electrical properties of the threads they are made of. In this study, two conductive sleeves were manufactured for the elbow and three for the knee using a Santoni circular machine with different combinations of elastomeric and non-elastomeric yarns. Linearity, repeatability and sensitivity of the sleeves resistance with strain were compared during 5 repetitive trials, each of them consisting of 4 sequences of 50 joint flexion-extension cycles. All knitted conductive sleeves registered motion over 1000 cycles, proving their suitability for joint motion tracking. In addition, sleeves whose inner layer was made only with nylon exhibited the highest sensitivity and predictability of changes (i.e. a linear trend of the non-elastic deformation). On the other hand, sleeves whose inner layer was made with lycra and polyester or lycra and nylon showed a more balanced performance in terms of linearity, sensitivity and repeatability either for low or high number of cycles. Based on requirements, knitted conductive sleeves show a potential for application in rehabilitation both in healthcare and sports.


Assuntos
Têxteis , Dispositivos Eletrônicos Vestíveis , Condutividade Elétrica , Movimento (Física) , Nylons
7.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 430-433, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018020

RESUMO

In this paper, we review several advances in different fields that provide new potential for brain-computer interfaces enabled by directly interfacing biological neural networks with electrodes, including recent successes with liquid injected conductive channels and mesh electronics supported by 3D scaffolds. Based on this review, it is clear that the success of biological neural connectivity is dependent on the precision and density of the inserted electrodes. In order to better understand the dynamics of this relationship, we propose a simple impedance-based electrode connectivity model, based on which we perform a simulation of the impact of both electrode density and electrode precision on the amount of information lost as part of the connection. Although the examples illustrated are more informative rather than conclusive, the fundamental takeaway from this work is that electrode density is a substantially important parameter while electrode precision is necessarily helpful.


Assuntos
Interfaces Cérebro-Computador , Condutividade Elétrica , Impedância Elétrica , Eletrodos , Eletrônica
8.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1440-1443, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018261

RESUMO

Electrical Impedance Tomography (EIT) can be used to estimate the electrical properties of the head tissues in a parametric approach. This modality is called parametric EIT or bounded EIT (bEIT). Typical bEIT protocols alternate between several current injection patterns with two current injection electrodes each: one source and one sink ("1-to-1"), while the rest of the electrodes measure the resulting electric potential. Then, one value of conductivity per tissue (e.g. scalp and/or skull) is estimated independently for each current injection pair. With these protocols, it is difficult to obtain local estimates of the skull tissue. Thus, the grand average of the estimates obtained from each pair is assigned to each tissue modeling them as homogeneous. However, it is known that these tissues are inhomogeneous within the same subject. We propose the use of current injection patterns with one source and many sinks ("1to-N") located at the opposite side of the head to build individual and inhomogeneous skull conductivity maps. We validate the method with simulations and compare its performance with equivalent maps generated by using the classical "1-to-1" patterns. The map generated by the novel method shows better spatial correlation with the more conductive spongy bone presence.Clinical Relevance- The novel bEIT protocol allows to map individual head models with spatially resolved skull conductivities in vivo and non-invasively for use in electroencephalography (EEG) source localization, transcranial electrical stimulation (TES) dose calculations and TES pattern optimization, without the risk of ionizing radiation associated with computed tomography (CT) scans.


Assuntos
Crânio , Tomografia Computadorizada por Raios X , Condutividade Elétrica , Eletroencefalografia , Couro Cabeludo , Crânio/diagnóstico por imagem
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2249-2252, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018455

RESUMO

We report on a unique microfluidic device that can enrich nanoparticles in a continuous flow by railing them along activated tracks (electrodes). This was achieved based on dielectrophoretic force and electrohydrodynamic drag (electrothermal rolls and AC electroosmosis) in both low and high conductive media. The results have implication for the isolation of high quality and pure nanoparticles such as exosomes from biofluids for applications in cancer diagnosis and prognosis.


Assuntos
Técnicas Analíticas Microfluídicas , Nanopartículas , Condutividade Elétrica , Eletro-Osmose , Dispositivos Lab-On-A-Chip
10.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(7): 1036-1043, 2020 Jul 30.
Artigo em Chinês | MEDLINE | ID: mdl-32895168

RESUMO

OBJECTIVE: To investigate the sensing volume of open-ended coaxial probe technique for measurement of dielectric characteristics. METHODS: A measurement model combining macro- measurement device with a layer model of dielectric properties parameters was established for evaluating the sensing volume of open-ended coaxial probe technique. We defined sensing depth and sensing diameter to describe the distance that could be detected in vertical and horizontal direction. Using a variety of materials with different dielectric properties (Teflon, deionized water, ethanol, and gradient concentration sodium chloride solution), a layered model of dielectric properties differentiation was established. The total combined uncertainties (TCU) were calculated for different output power, and the output power was controlled to increase from -50 dBm to 15 dBm to calibrate the error range of the dielectric properties measurement system. The optimal output power range was determined based on the results of TCU test. In sensing volume measurement experiment, we set the control groups based on measurement parameters that potentially affect the sensing volume including output power (-10, -5, 0, 3, 6, and 9 dBm), frequency (1-500 MHz), Teflon, deionized water, and ethanol to form a dielectric constant difference between high and low contrast groups. Different concentrations of sodium chloride solution and Teflon were used to generate a conductivity difference between high and low contrast groups. These groups were tested in the sensing depth and sensing diameter measurement experiments. RESULTS: The result of TCU test indicated that accurate and stable measurement results could be obtained when the output power was greater or equal to-10 dBm (TCU < 2%). Sensing volume measurement experiment revealed a positive correlation between the sensing depth and output power (P < 0.05). As the measured power increased, the sensing depth gradually increased in deionized water and ethanol, and the difference reached 70 µm. The sensing depth was negatively correlated frequency (P < 0.05). As the concentration of sodium chloride solution increased, the corresponding sensing depth gradually decreased, with a difference reaching 270 µm. The sensing depth of high dielectric materials was greater than that pf low dielectric materials. The results of sensing diameter measurement were not obviously affected by the measurement parameters, and the sensing diameter was stable in a fixed range (1.0 to 1.8 mm) between the diameter of the inner conductor and the diameter of the insulation layer, and was less than the diameter of the probe. CONCLUSIONS: The sensing volume of open-ended coaxial probe technique is affected by measurement parameters and dielectric properties of materials, which significantly affect the sensing depth.


Assuntos
Condutividade Elétrica , Algoritmos
11.
Nat Commun ; 11(1): 4683, 2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32943621

RESUMO

Wearable dry electrodes are needed for long-term biopotential recordings but are limited by their imperfect compliance with the skin, especially during body movements and sweat secretions, resulting in high interfacial impedance and motion artifacts. Herein, we report an intrinsically conductive polymer dry electrode with excellent self-adhesiveness, stretchability, and conductivity. It shows much lower skin-contact impedance and noise in static and dynamic measurement than the current dry electrodes and standard gel electrodes, enabling to acquire high-quality electrocardiogram (ECG), electromyogram (EMG) and electroencephalogram (EEG) signals in various conditions such as dry and wet skin and during body movement. Hence, this dry electrode can be used for long-term healthcare monitoring in complex daily conditions. We further investigated the capabilities of this electrode in a clinical setting and realized its ability to detect the arrhythmia features of atrial fibrillation accurately, and quantify muscle activity during deep tendon reflex testing and contraction against resistance.


Assuntos
Condutividade Elétrica , Epiderme , Monitorização Fisiológica/instrumentação , Movimento (Física) , Pele , Artefatos , Impedância Elétrica , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , Eletrodos , Eletroencefalografia/instrumentação , Eletroencefalografia/métodos , Eletromiografia/instrumentação , Eletromiografia/métodos , Desenho de Equipamento , Humanos , Monitorização Fisiológica/métodos , Polímeros/química , Sorbitol
12.
PLoS One ; 15(8): e0236409, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853253

RESUMO

This paper proposes an alternative approach to extract transformer's winding parameters of resistance (R), inductance (L), capacitance (C) and conductance (G) based on Finite Element Method (FEM). The capacitance and conductance were computed based on Fast Multiple Method (FMM) and Method of Moment (MoM) through quasi-electrostatics approach. The AC resistances and inductances were computed based on MoM through quasi-magnetostatics approach. Maxwell's equations were used to compute the DC resistances and inductances. Based on the FEM computed parameters, the frequency response of the winding was obtained through the Bode plot function. The simulated frequency response by FEM model was compared with the simulated frequency response based on the Multi-conductor Transmission Line (MTL) model and the measured frequency response of a 33/11 kV, 30 MVA transformer. The statistical indices such as Root Mean Square Error (RMSE) and Absolute Sum of Logarithmic Error (ASLE) were used to analyze the performance of the proposed FEM model. It is found that the simulated frequency response by FEM model is quite close to measured frequency response at low and mid frequency regions as compared to simulated frequency response by MTL model based on RMSE and ASLE analysis.


Assuntos
Capacitância Elétrica , Fontes de Energia Elétrica , Análise de Elementos Finitos , Simulação por Computador , Condutividade Elétrica , Eletricidade Estática
13.
An Acad Bras Cienc ; 92(suppl 1): e20181112, 2020 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-32756839

RESUMO

This work aimed to study different seeding rates in soybean, at management zones determined by the mapping of the soil apparent electrical conductivity (ECa) and its relationships with plant phenology and grain yield (GY). The experiment consisted of a completely randomized design, with six replications. The plant population ranged between 311,000, 360,000, and 422,000 plants ha-1, and the fixed population (360,000 plants ha-1). The management zone with the least yield potential, received the highest seed population. The management zone with the highest plant vigor potential, received the lowest seed population. The variables plant height, Normalized Difference Vegetation Index (NDVI) at 50, 66, and 92 days after emergence (DAE), one hundred-grain weight, and GY were analyzed. ECa maps can be used to decide the seed population of the soybean. The decision strategy of increasing 20% of the seed soybean population on the smaller ECa map zones, and decreasing 20% seed population on higher ECa zones was effective and resulted in similar GY, even with the negative pressure of the high resistance of penetration (RP) values in some zones. GY map variability was influenced by ECa 0-0.2 m, by NDVI at 92 DAE and by RP 0.4-0.6 m soil layer.


Assuntos
Soja , Condutividade Elétrica , Sementes , Solo
14.
J Chromatogr A ; 1626: 461262, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797810

RESUMO

In this paper, a semi-analytical investigation was performed to study the effect of the geometrical parameters of insulator-based dielectrophoresis (iDEP) systems for cell free DNA (cfDNA) trapping. For this purpose, first electrical potential and fluid flow fields were calculated by solving the governing equations including Poisson and Navier-stokes equations with appropriate boundary conditions (BCs) and then a Lagrangian approach was utilized to analyze the motion of cfDNA under the most important forces affected on it including Brownian, Drag, electrophoresis and dielectrophoresis (DEP) forces. The effect of the different parameters such as the electrical conductivity of the medium, shape and geometrical parameters of the insulators on the dielectrophoretic behavior of cfDNA was studied and the optimal value of these parameters was presented. Finally, in order to predict the minimum voltage required for cfDNA trapping, artificial neural network (ANN) was utilized and a relation between input and output parameters was introduced.


Assuntos
Ácidos Nucleicos Livres/química , Eletroforese/métodos , Nanopartículas/química , Condutividade Elétrica , Técnicas Analíticas Microfluídicas , Redes Neurais de Computação
15.
Science ; 369(6506): 904, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32820106
16.
J Environ Manage ; 271: 110978, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778277

RESUMO

Geosynthetic clay liners (GCL) are increasingly being used as a major component of barrier systems replacing compacted clay liners due to their very low permeability and speed of installation. Researchers and practitioners have identified the critical role of the GCL overlap that presents constant challenges encountered in maintaining the designed hydraulic conductivity. This study presents a series of flow box tests conducted to evaluate and improve understanding of the combined effect of each of the four contributing factors, namely, overlap width, supplemental bentonite applied at the overlap, the overburden confining stress, and the hydraulic head acting on the GCL overlap. The findings reveal that the overlap width is the most significant parameter affecting the design hydraulic conductivity. The application of a minimum overburden stress to maintain the designed hydraulic performance is also recognised as important. The effect of confinement due to higher hydraulic heads is of interest to practitioners. The supplemental bentonite has the least effect on the GCL overlap hydraulic performance even though it enhances the function of the overlap seam. This knowledge addresses the inadequacy of published GCL overlap experimental data comparing the effect of different factors affecting its hydraulic performance. It also assists industry practitioners to design and specify the overlap criterion for a specific application depending on the product specifications and site conditions. The results of this research will help minimise failures of liner systems in barrier applications such as landfills, mines, tailing dams substantially to reduce the potential risk of groundwater contamination.


Assuntos
Argila , Eliminação de Resíduos , Silicatos de Alumínio , Condutividade Elétrica , Instalações de Eliminação de Resíduos
17.
Environ Sci Pollut Res Int ; 27(30): 37455-37467, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32767011

RESUMO

Slope failure is a one of major process that causes severe landform variation and environment variation, and slope failure has become a major hidden danger to human settlement and urban construction in this vast loess region. The physical model of slope failure as induced by artificial rainfall was constructed in the field, and monitored the pore water pressure (PWP), earth stress (ES), volumetric water content (VWC), electrical conductivity (EC), and temperature (T) of the soil using this physical simulation. The surface morphology of slope started to occur in the slope as a result of erosion caused by rainfall and rainwater infiltration at the beginning of the experiment; concurrently, PWP, ES, VWC, and EC were increased gradually. Meanwhile, the saturated weight of the soil rose. In the middle of the experiment, PWP, ES, VWC, and EC were increased rapidly as the artificial rainfall continued, and the ratio of soil pore the soil fell. The slope landform was obviously occurred during the experiment, when it was noted that PWP, ES, VWC, and EC of the soil rapidly decreased. Afterwards, slope failure evolved into a debris flow; eventually, the landform was entirely changed in the slope. The soil became more compact toward the end of the experiment, and PWP, ES, VWC, and EC were slowly increased; these factors indicated that the loess slope was temporarily stable. This study could potentially be used to provide the relevant parameters for numerical simulations of landform variation in loess regions, and provide reference for regional land use planning and environmental development.


Assuntos
Chuva , Movimentos da Água , China , Conservação dos Recursos Naturais , Condutividade Elétrica , Solo , Água/análise
18.
PLoS One ; 15(8): e0238061, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32846429

RESUMO

The method of non-aqueous conductivity titration (NACT) of organic weak acids was applied to quickly and accurately determine the phenolic-hydroxyl and carboxyl-groups contents in humic acid. By varying the pH of the humic-acid sample, the concentration of the titrant, and the nitrogen-gas flow rate, the optimal titration conditions were determined to be a sample pH of 4, titrant concentration of 0.05 mol/L, and nitrogen-gas flow rate of 80 mL/min. Applying the detection method to p-hydroxybenzoic acid showed that its phenolic-hydroxyl content was 758.82±111.76 cmol/kg and carboxyl content was 744.44±51.11 cmol/kg. The theoretical phenolic-hydroxyl and carboxyl-groups contents of the p-hydroxybenzoic acid were 723.96 cmol/kg respectively, indicating that the method can accurately quantify the carboxyl and phenolic-hydroxyl groups in the sample. The NACT was used to measure the phenolic-hydroxyl and carboxyl-groups contents in humic acid quickly and accurately. In addition, 29 humic acid samples from 8 provinces of China covering the main humic-acid producing areas were collected and analyzed for acidic-groups content using the reported method.


Assuntos
Técnicas Eletroquímicas/métodos , Substâncias Húmicas/análise , China , Condutividade Elétrica , Eletrodos , Concentração de Íons de Hidrogênio , Hidroxibenzoatos/análise , Fenóis/química , Solo/química
19.
Nature ; 585(7823): 129-134, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32848250

RESUMO

Transmembrane channels and pores have key roles in fundamental biological processes1 and in biotechnological applications such as DNA nanopore sequencing2-4, resulting in considerable interest in the design of pore-containing proteins. Synthetic amphiphilic peptides have been found to form ion channels5,6, and there have been recent advances in de novo membrane protein design7,8 and in redesigning naturally occurring channel-containing proteins9,10. However, the de novo design of stable, well-defined transmembrane protein pores that are capable of conducting ions selectively or are large enough to enable the passage of small-molecule fluorophores remains an outstanding challenge11,12. Here we report the computational design of protein pores formed by two concentric rings of α-helices that are stable and monodisperse in both their water-soluble and their transmembrane forms. Crystal structures of the water-soluble forms of a 12-helical pore and a 16-helical pore closely match the computational design models. Patch-clamp electrophysiology experiments show that, when expressed in insect cells, the transmembrane form of the 12-helix pore enables the passage of ions across the membrane with high selectivity for potassium over sodium; ion passage is blocked by specific chemical modification at the pore entrance. When incorporated into liposomes using in vitro protein synthesis, the transmembrane form of the 16-helix pore-but not the 12-helix pore-enables the passage of biotinylated Alexa Fluor 488. A cryo-electron microscopy structure of the 16-helix transmembrane pore closely matches the design model. The ability to produce structurally and functionally well-defined transmembrane pores opens the door to the creation of designer channels and pores for a wide variety of applications.


Assuntos
Simulação por Computador , Genes Sintéticos/genética , Canais Iônicos/química , Canais Iônicos/genética , Modelos Moleculares , Biologia Sintética , Linhagem Celular , Microscopia Crioeletrônica , Cristalografia por Raios X , Condutividade Elétrica , Escherichia coli/genética , Escherichia coli/metabolismo , Hidrazinas , Canais Iônicos/metabolismo , Transporte de Íons , Lipossomos/metabolismo , Técnicas de Patch-Clamp , Porinas/química , Porinas/genética , Porinas/metabolismo , Engenharia de Proteínas , Estrutura Secundária de Proteína , Solubilidade , Água/química
20.
Bioresour Technol ; 317: 123977, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32799079

RESUMO

Methanogenesis can be promoted by the addition of conductive materials. Although stimulating effects of conductive materials on methane (CH4) production has been extensively reported, the crucial roles on recovering methanogenic activities under inhibitory conditions have not been systematically discussed. This critical review presents the current findings on the effects of conductive materials in methanogenic systems under volatile fatty acids (VFAs), ammonia, sulfate, and nano-cytotoxicity stressed conditions. Conductive materials induce fast VFAs degradation, avoiding VFAs accumulation during anaerobic digestion. Under high ammonia concentrations, conductive materials may ensure sufficient energy conservation for methanogens to maintain intracellular pH and proton balance. When encountering the competition of sulfate-reducing bacteria, conductive materials can benefit electron competitive capability of methanogens, recovering CH4 production activity. Conductive nanomaterials stimulate the excretion of extracellular polymeric substances, which can prevent cells from nano-cytotoxicity. Future perspectives about unraveling mitigation mechanisms induced by conductive materials in methanogenesis processes are further discussed.


Assuntos
Amônia , Metano , Anaerobiose , Condutividade Elétrica , Elétrons , Ácidos Graxos Voláteis
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