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Journal of the American Chemical Society Feb 2020We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new...
We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new catalytic system is able to productively engage aryl chlorides with reduction potentials hundreds of millivolts beyond the potential of Na in productive radical coupling reactions. The aryl radicals produced via this strategy can be leveraged for both carbon-carbon and carbon-heteroatom bond-forming reactions. Through direct comparison, we illustrate the reactivity and selectivity advantages of this approach relative to electrolysis and photoredox catalysis.
Topics: Catalysis; Chlorides; Electrons; Oxidation-Reduction; Photochemical Processes
PubMed: 31951393
DOI: 10.1021/jacs.9b12328 -
Science (New York, N.Y.) Jan 1969Membrane currents were measured in thin bundles of dog ventricular myocardium under voltage-clamp conditions. A rather large initial inward current which had an...
Membrane currents were measured in thin bundles of dog ventricular myocardium under voltage-clamp conditions. A rather large initial inward current which had an equilibrium potential at about + 55 millivolts could be recorded. When the external sodium concentration was reduced, the equilibrium potential for this current was shifted by the amount predicted theoretically for a current carried solely by sodium ions. The size of the sodium inward current (I(Na)) was largely dependent on the preceding membrane potential. The I(Na) was completely inactivated if the membrane potential was as low as -45 millivolts. Sodium ions are the main carrier of charge during the rapid depolarization phase of the action potential.
Topics: Action Potentials; Animals; Dogs; Heart; Heart Ventricles; In Vitro Techniques; Membrane Potentials; Myocardium; Papillary Muscles; Sodium
PubMed: 5762778
DOI: 10.1126/science.163.3865.397 -
Methods in Enzymology 2021Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are...
Membrane potential is a fundamental biophysical parameter common to all of cellular life. Traditional methods to measure membrane potential rely on electrodes, which are invasive and low-throughput. Optical methods to measure membrane potential are attractive because they have the potential to be less invasive and higher throughput than classic electrode based techniques. However, most optical measurements rely on changes in fluorescence intensity to detect changes in membrane potential. In this chapter, we discuss the use of fluorescence lifetime imaging microscopy (FLIM) and voltage-sensitive fluorophores (VoltageFluors, or VF dyes) to estimate the millivolt value of membrane potentials in living cells. We discuss theory, application, protocols, and shortcomings of this approach.
Topics: Fluorescent Dyes; Membrane Potentials; Microscopy, Fluorescence; Optical Imaging
PubMed: 34099175
DOI: 10.1016/bs.mie.2021.02.009 -
Science (New York, N.Y.) Jun 1966Changes in the membrane potential of the S-potential-producing cells (S-cells) in the isolated retina of fish (Gerridae) were correlated with changes in oxygen...
Changes in the membrane potential of the S-potential-producing cells (S-cells) in the isolated retina of fish (Gerridae) were correlated with changes in oxygen concentration. During brief hypoxia the changes in potential consisted of initial depolarization and subsequent hyperpolarization to near 70 millivolts. Depolarization occurred when oxygen concentration was reduced to a level of from 13 to 10 percent, and hyperpolarization occurred on reduction from 10 to 2.5 percent; there was yariation from cell to cell. The recovery of S-cell function from anoxia was fast in oxygen but slow in air. The results show that the S-cell stops functioning in seconds without oxygen; hence this kind of cellular element in the nervous system is much more sensitive to oxygen deprivation than other cells studied thus far.
Topics: Animals; Cell Membrane; Electrophysiology; Fishes; Hypoxia; In Vitro Techniques; Oxygen; Retina
PubMed: 5936886
DOI: 10.1126/science.152.3729.1621 -
Frontiers in Microbiology 2019Microorganisms can increase the open-circuit potential of stainless steel immersed in seawater of several hundred millivolts in a phenomenon called ennoblement. It...
Microorganisms can increase the open-circuit potential of stainless steel immersed in seawater of several hundred millivolts in a phenomenon called ennoblement. It raises the chance of corrosion as the open-circuit potential may go over the pitting corrosion potential. Despite the large impact of the ennoblement, no unifying mechanisms have been described as responsible for the phenomenon. Here we show that the strict electrotroph bacterium " Tenderia electrophaga" is detected as an ennoblement biomarker and is only present at temperatures at which we observe ennoblement. This bacterium was previously enriched in biocathode systems. Our results suggest that " Tenderia electrophaga," and its previously described extracellular electron transfer metabolism coupled to oxygen reduction activity, could play a central role in modulating stainless steel open-circuit potential and consequently mediating ennoblement.
PubMed: 30792705
DOI: 10.3389/fmicb.2019.00170 -
FEMS Microbiology Reviews Jan 2010In microbial fuel cells and electrolysis cells (MXCs), anode-respiring bacteria (ARB) oxidize organic substrates to produce electrical current. In order to develop an... (Review)
Review
In microbial fuel cells and electrolysis cells (MXCs), anode-respiring bacteria (ARB) oxidize organic substrates to produce electrical current. In order to develop an electrical current, ARB must transfer electrons to a solid anode through extracellular electron transfer (EET). ARB use various EET mechanisms to transfer electrons to the anode, including direct contact through outer-membrane proteins, diffusion of soluble electron shuttles, and electron transport through solid components of the extracellular biofilm matrix. In this review, we perform a novel kinetic analysis of each EET mechanism by analyzing the results available in the literature. Our goal is to evaluate how well each EET mechanism can produce a high current density (> 10 A m(-2)) without a large anode potential loss (less than a few hundred millivolts), which are feasibility goals of MXCs. Direct contact of ARB to the anode cannot achieve high current densities due to the limited number of cells that can come in direct contact with the anode. Slow diffusive flux of electron shuttles at commonly observed concentrations limits current generation and results in high potential losses, as has been observed experimentally. Only electron transport through a solid conductive matrix can explain observations of high current densities and low anode potential losses. Thus, a study of the biological components that create a solid conductive matrix is of critical importance for understanding the function of ARB.
Topics: Bacteria; Bioelectric Energy Sources; Biofilms; Electrodes; Electrolysis; Electrons; Kinetics; Nanowires
PubMed: 19895647
DOI: 10.1111/j.1574-6976.2009.00191.x -
Nano-micro Letters Apr 2023Ionic thermoelectrics (i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin....
Ionic thermoelectrics (i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin. However, as ions cannot enter external circuit, the utilization of i-TE is currently based on capacitive charge/discharge, which results in discontinuous working mode and low energy density. Here, we introduce an ion-electron thermoelectric synergistic (IETS) effect by utilizing an ion-electron conductor. Electrons/holes can drift under the electric field generated by thermodiffusion of ions, thus converting the ionic current into electrical current that can pass through the external circuit. Due to the IETS effect, i-TE is able to operate continuously for over 3000 min. Moreover, our i-TE exhibits a thermopower of 32.7 mV K and an energy density of 553.9 J m, which is more than 6.9 times of the highest reported value. Consequently, direct powering of electronics is achieved with i-TE. This work provides a novel strategy for the design of high-performance i-TE materials.
PubMed: 37052861
DOI: 10.1007/s40820-023-01077-7 -
Nuclear Medicine decision makers in need of help: The remote places' cyclotron installation example.Hellenic Journal of Nuclear Medicine 2021
Topics: Cyclotrons; Decision Making; Humans; Nuclear Medicine; Radionuclide Imaging
PubMed: 34901971
DOI: 10.1967/s002449912414 -
Nanoscale Advances Mar 2022Harvesting ocean wave energy through carbon-based materials, particularly graphene, is receiving increasing attention. However, the complicated fabrication process and...
Harvesting ocean wave energy through carbon-based materials, particularly graphene, is receiving increasing attention. However, the complicated fabrication process and the low output power of the present monolayer graphene-based wave energy generators limit their further application. Here, we demonstrate the facile fabrication of a new type of wave energy generator based on graphene/TiO nanoparticle composite films using the doctor-blading method. The developed wave energy harvesting device exhibits a high open-circuit voltage of up to 75 millivolts and a high output power up to 1.8 microwatts. A systematic study was conducted to explore the optimal conditions for the energy harvesting performance.
PubMed: 36134363
DOI: 10.1039/d1na00658d -
Sensors (Basel, Switzerland) Dec 2022DAS and geophones are the two most popular sensors for borehole seismic acquisition. As such, it is important to get a good understanding of how these two types of...
DAS and geophones are the two most popular sensors for borehole seismic acquisition. As such, it is important to get a good understanding of how these two types of sensors compare to each other. The natural measurand for the techniques is different; millivolts are approximately proportional to particle velocities for geophones vs. changes in the phase of light linked to the changes in strain on the sensing fibre. This paper focuses on the experimental comparison of absolute values of these measurands derived from a VSP survey acquired in Curtin GeoLab training well. We describe the acquisition setup for the walk-away VSP acquired with DAS and geophones, allowing the direct comparison and the workflow, which we can use to represent the data in strain rate. Albeit this is unlikely to be universal, we find that the absolute values are similar for this experimental setup.
PubMed: 36502212
DOI: 10.3390/s22239510