Proton Flow Research Articles

Non-Electroneutrality Generated by Bacteriorhodopsin-Incorporated Membranes Enhances the Conductivity of a Gelatin Memory Device.

We have previously demonstrated the potential of gelatin films as a memory device, offering a novel approach for writing, reading, and erasing through the manipulation of gelatin structure and bound water content. Here, we discovered that incorporating a bacteriorhodopsin (BR)-lipid membrane into the gelatin devices can further increase the electron conductivity of the polypeptide-bound water network and the ON/OFF ratio of the device by two folds. Our photocurrent measurements show that the BR incorporated in the membrane sandwiched in a gelatin device can generate a net proton flow from the counter side to the deposited side of the membrane. This leads to the establishment of non-electroneutrality on the gelatin films adjacent to the BR-incorporated membrane. Our Raman spectroscopy results show that BR proton pumping in the ON state gelatin device increases the bound water presence and promotes polypeptide unwinding compared to devices without BR. These findings suggest that the non-electroneutrality induced by BR proton pumping can increase the extent of polypeptide unwinding within the gelatin matrix, consequently trapping more bound water within the gelatin-bound water network. The resulting rise in hydrogen bonds could expand electron transfer routes, thereby enhancing the electron conductivity of the memory device in the ON state.

Bayesian inference of in-medium baryon-baryon scattering cross sections from HADES proton flow data

Within a Bayesian statistical framework using a Gaussian Process emulator for an isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model simulator of heavy-ion reactions at intermediate energies, we infer from the HADES proton flow data the posterior probability distribution functions of in-medium baryon-baryon scattering cross section modification factor X with respect to free-space and the corresponding incompressibility K of nuclear matter as well as their correlation function. The mean value of X is found to be X=1.32−0.40+0.28 at 68% confidence level assuming the nuclear incompressibility K will not exceed 400 MeV, providing circumstantial evidence for enhanced baryon-braryon scattering cross sections in hot and dense nuclear matter.

Mitochondrial uncouplers impair human sperm motility without altering ATP content†.

In human spermatozoa, the electrochemical potentials across the mitochondrial and plasma membranes are related to sperm functionality and fertility, but the exact role of each potential has yet to be clarified. Impairing sperm mitochondrial function has been considered as an approach to creating male or unisex contraceptives, but it has yet to be shown whether this approach would ultimately block the ability of sperm to reach or fertilize an egg. To investigate whether the mitochondrial and plasma membrane potentials are necessary for sperm fertility, human sperm were treated with two small-molecule mitochondrial uncouplers (niclosamide ethanolamine and BAM15) that depolarize membranes by inducing passive proton flow, and evaluated the effects on a variety of sperm physiological processes. BAM15 specifically uncoupled human sperm mitochondria while niclosamide ethanolamine induced proton current in the plasma membrane in addition to depolarizing the mitochondria. In addition, both compounds significantly decreased sperm progressive motility with niclosamide ethanolamine having a more robust effect. However, these uncouplers did not reduce sperm adenosine triphosphate (ATP) content or impair other physiological processes, suggesting that human sperm can rely on glycolysis for ATP production if mitochondria are impaired. Thus, systemically delivered contraceptives that target sperm mitochondria to reduce their ATP production would likely need to be paired with sperm-specific glycolysis inhibitors. However, since niclosamide ethanolamine impairs sperm motility through an ATP-independent mechanism, and niclosamide is FDA approved and not absorbed through mucosal membranes, it could be a useful ingredient in on-demand, vaginally applied contraceptives.

Investigating the role of electric fields on flow harmonics in heavy-ion collisions

Using the blast-wave model, we explore the effect of electric fields on spectra and flow harmonics (especially the elliptic flow) for charged pions and protons. We incorporate the first-order correction to the single-particle distribution function due to the electric fields and the dissipative effect while calculating the invariant yields of hadrons in the Cooper–Frye prescription at the freezeout hypersurface. We find a noticeable correction to the directed and elliptic flow of pions and protons for unidirectional and azimuthal asymmetric electric fields of a magnitude in the transverse plane. Further, we observe mass dependency of the directed flow generated due to the electric fields. The splitting of particle and antiparticle’s elliptic flow due to the electric fields is also discussed.

Simulation of collective flow of protons and deuterons in Au+Au collisions at Ebeam=1.23A GeV with the isospin-dependent quantum molecular dynamics model

Collective flows of protons and deuterons for $\text{Au}+\text{Au}$ collisions at beam energy ${E}_{\text{beam}}=1.23A \mathrm{GeV}$ were simulated by an isospin-dependent quantum molecular dynamics model. Two coalescence models, namely, naive coalescence and dynamical coalescence models, are compared for the formation of deuterons. After a reasonable agreement of the proton and deuteron rapidity spectra with the high acceptance dielectron spectrometer data is obtained, we apply an event-plane method to calculate the first four order collective flow coefficients and the ratios of $\ensuremath{\langle}{v}_{4}\ensuremath{\rangle}/{\ensuremath{\langle}{v}_{2}\ensuremath{\rangle}}^{2}$ and $\ensuremath{\langle}{v}_{3}\ensuremath{\rangle}/(\ensuremath{\langle}{v}_{1}\ensuremath{\rangle}\ensuremath{\langle}{v}_{2}\ensuremath{\rangle})$ and observe the scaling of the number of constituent nucleons between protons and deuterons. In addition, the dependence of ${\ensuremath{\varepsilon}}_{n}$ versus $\ensuremath{\langle}{v}_{n}\ensuremath{\rangle}$ and the ratio $\ensuremath{\langle}{v}_{n}\ensuremath{\rangle}/{\ensuremath{\varepsilon}}_{n}$ on the centrality is obtained. Finally, the Pearson coefficients $\text{corr}({v}_{n},{v}_{m})$ between the first four harmonic flows for protons and deuterons are studied as a function of rapidity and centrality.

A microfluidic proton flow reactor system: In-situ visualisation of hydrogen evolution and storage in carbon-based slurry electrodes

A Proton flow reactor (PFR) system stores energy in the form of hydrogen in porous carbon particles in slurry electrodes. However, the hydrogen storage mechanisms and the reactions in this system are not well understood. In this study, we design and fabricate a microfluidic proton flow reactor (MPFR) as a small-scale PFR to enable in-situ visualisation of the key processes underlying PFR operations. We observe the behaviour of slurries and water in both hydrogen and oxygen sides with emphasis on processes in the vicinity of membranes. We use fluorescence microscopy with quinine to visualize hydronium transport from the oxygen to the hydrogen side and employ in-situ Raman spectroscopy to analyze surface structural changes in carbon particles before and after charging. Fluorescence microscopy demonstrates the formation of hydronium ions on the oxygen side and their subsequent migration to the hydrogen side, proving that the oxygen evolution reaction occurs on the oxygen side. Raman heat maps prove the formation of carbon–hydrogen bonding in particles after they are charged with PFR. Although the MPFR is operated at non-optimal slurry concentrations to allow optical access, we demonstrate that it provides maximum hydrogen storage capacity of 0.64 wt%.

Directed and elliptic flows of protons and deuterons in HADES Au+Au collisions at [formula omitted] GeV

Within a transport model coupled with a microscopic coalescence model, the directed and elliptic flows of protons and deuterons as well as their scalling properties are studied in the centrality of 20-30% Au+Au collisions at sNN=2.4 GeV. It is found that the flows as well as their scaling properties simulated with the isospin- and momentum-dependent nuclear mean field with an incompressibility K0=230 MeV fit fairly the HADES data, while those simulated with the commonly used momentum-independent nuclear mean field with an incompressibility K0=380 MeV can only fit partially the HADES data. Moreover, by checking the rapidity distributions of both protons and deuterons in the centrality of 0-10% Au+Au collisions at sNN=2.4 GeV, we find that the rapidity distributions of deuterons are underestimated while those of protons are overestimated by the simulations with the momentum-independent nuclear mean field. In contrast, the rapidity distributions of both protons and deuterons simulated with the isospin- and momentum-dependent nuclear mean field are in good agreement with the HADES data. Our findings imply that the momentum dependence of nuclear mean field is an unavoidable feature for a fundamental understanding of nuclear matter properties and for the successful interpretation of the HADES data.

Bio-Electrochemical Fuel CELL: A Review Study on Electricity Generation Using Bio-Waste

This era is all about energy, humans cannot survive without energy. Conventional energy resources are not enough to fulfill the needs of energy that’s why it is necessary to find alternate energy resources that will be efficient and environment friendly. Microbial Fuel Cell (MFC) is one of the reasonably low costs and is considered as environment friendly It degrades the harmful substance during production of electricity.This technology helps out for the producing of electricity by using the microbes. The generation of electricity is the new form of non-renewable energy by treating of the waste water from different types of effluent. The purpose of this technology is to produce the electricity that is environment friendly and sustainable. This review is also the part of research which is also to make a comparison of different MFC feeds which have unique chemical composition and are rich of various biological species and designing. This report also contains the discussion of MFC principle, necessary components, bacteria that are responsible for electricity production. This MFC contain the different batch type of reactor and in each reactor anode and cathode are dipped for time to check the response of flow of electron. Electrodes are used for drawing the comparison data of the MFC and giving new direction for the researchers. Salt bridge or membrane is connected between the reactor for the flow of proton to the cathode side and oxygen is supplied in the cathode compartment.

Testing the phase transition parameters inside neutron stars with the production of protons and lambdas in relativistic heavy-ion collisions

We demonstrate the consistency of the quark deconfinement phase transition parameters in the beta-stable neutron star matter and in the nearly symmetric nuclear matter formed in heavy-ion collisions (HICs). We investigate the proton and $\mathrm{\ensuremath{\Lambda}}$ flow in $\mathrm{Au}+\mathrm{Au}$ collisions at 3 and $4.5\text{ }\text{ }\mathrm{GeV}/\mathrm{nucleon}$ incident beam energies with the pure hadron cascade version of a multiphase transport model. The phase transition in HICs and neutron stars is described based on a class of hybrid equations of state from the quark mean-field model for the hadronic phase and a constant-speed-of-sound parametrization for the high-density quark phase. The measurements of the anisotropic proton flow at $3\text{ }\text{ }\mathrm{GeV}/\mathrm{nucleon}$ by the STAR Collaboration favor a relatively low phase transition density lower than $\ensuremath{\sim}2.5$ times saturation density indicated by the gravitational wave and electromagnetic observations of neutron stars. And the proton flow data at the higher energy of $4.5\text{ }\text{ }\mathrm{GeV}/\mathrm{nucleon}$ can be used to effectively constrain the softness of high-density quark matter equations of state. Finally, compared to the proton flow, the $\mathrm{\ensuremath{\Lambda}}$ flow is found to be less sensitive and not constraining to the equations of state.

Impact of engineering the ATP synthase rotor ring on photosynthesis in tobacco chloroplasts.

The chloroplast ATP synthase produces the ATP needed for photosynthesis and plant growth. The trans-membrane flow of protons through the ATP synthase rotates an oligomeric assembly of c subunits, the c-ring. The ion-to-ATP ratio in rotary F1F0-ATP synthases is defined by the number of c-subunits in the rotor c-ring. Engineering the c-ring stoichiometry is, therefore, a possible route to manipulate ATP synthesis by the ATP synthase and hence photosynthetic efficiency in plants. Here, we describe the construction of a tobacco (Nicotiana tabacum) chloroplast atpH (chloroplastic ATP synthase subunit c gene) mutant in which the c-ring stoichiometry was increased from 14 to 15 c-subunits. Although the abundance of the ATP synthase was decreased to 25% of wild-type (WT) levels, the mutant lines grew as well as WT plants and photosynthetic electron transport remained unaffected. To synthesize the necessary ATP for growth, we found that the contribution of the membrane potential to the proton motive force was enhanced to ensure a higher proton flux via the c15-ring without unwanted low pH-induced feedback inhibition of electron transport. Our work opens avenues to manipulate plant ion-to-ATP ratios with potentially beneficial consequences for photosynthesis.

Changes within the central stalk of E. coli F1Fo ATP synthase observed after addition of ATP

F1Fo ATP synthase functions as a biological generator and makes a major contribution to cellular energy production. Proton flow generates rotation in the Fo motor that is transferred to the F1 motor to catalyze ATP production, with flexible F1/Fo coupling required for efficient catalysis. F1Fo ATP synthase can also operate in reverse, hydrolyzing ATP and pumping protons, and in bacteria this function can be regulated by an inhibitory ε subunit. Here we present cryo-EM data showing E. coli F1Fo ATP synthase in different rotational and inhibited sub-states, observed following incubation with 10 mM MgATP. Our structures demonstrate how structural transitions within the inhibitory ε subunit induce torsional movement in the central stalk, thereby enabling its rotation within the Fο motor. This highlights the importance of the central rotor for flexible coupling of the F1 and Fo motors and provides further insight into the regulatory mechanism mediated by subunit ε.

Proton and Λ flow and the equation of state at high density

Results on proton and Λ flow, calculated with the UrQMD model that incorporates different realistic density dependent equations of state, are presented. It is shown that the proton and hyperon flow shows sensitivity to the equation of state and especially to the appearance of a phase transition at densities below 4n0. Even though qualitatively hyperons and protons exhibit the same beam energy dependence of the flow, the quantitative results are different. In this context it is suggested that the hyperon measurements can be used to study the density dependence of the hyperon interaction in high density QCD matter.

Purification of the Transmembrane Polypeptide Channel Complex of the Salmonella Flagellar Type III Secretion System.

Many motile bacteria employ the flagellar type III secretion system (fT3SS) to build the flagellum on the cell surface. The fT3SS consists of a transmembrane export gate complex, which acts as a proton/protein antiporter that couples proton flow with flagellar protein export, and a cytoplasmic ATPase ring complex, which works as an activator of the export gate complex. Three transmembrane proteins, FliP, FliQ, and FliR, form a core structure of the export gate complex, and this core complex serves as a polypeptide channel that allows flagellar structural subunits to be translocated across the cytoplasmic membrane. Here, we describe the methods for overproduction, solubilization, and purification of the Salmonella FliP/FliQ/FliR complex.

Model Study of the Energy Dependence of Anisotropic Flow in Heavy-Ion Collisions at sNN = 2–4.5 GeV

The anisotropic flow is one of the important observables sensitive to the equation of state (EOS) and transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. In this work, we report a detailed multi-differential study of the directed (v1), elliptic (v2), triangular (v3), and quadrangular (v4) flow coefficients of protons in relativistic heavy-ion collisions at sNN = 2.2–4.5 GeV using several hadronic transport models. Recent published results for Au + Au collisions at sNN = 2.4 GeV from HADES experiment and at sNN = 3.0 GeV from the STAR experiment have been used for comparison. The study motivates further experimental investigations of the anisotropic collective flow of protons and neutrons in a high baryon density region.

Artificial Water Channels—Progress Innovations and Prospects

Artificial Water Channels—Progress Innovations and Prospects

The high-density equation of state in heavy-ion collisions: constraints from proton flow

A set of different equations of state is implemented in the molecular dynamics part of a non-equilibrium transport simulation (UrQMD) of heavy-ion collisions. It is shown how different flow observables are affected by the density dependence of the equation of state. In particular, the effects of a phase transition at high density are explored, including an expected reduction in mean m_T. We also show that an increase in v_2 is characteristic for a strong softening of the equation of state. The phase transitions with a low coexistence density, n_{text {CE}}<4 n_0, show a distinct minimum in the slope of the directed flow as a function of the beam energy, which would be a clear experimental signal. By comparing our results with experimental data, we can exclude any strong phase transition at densities below 4n_0.

Nuclear Bubble Configuration in Heavy-Ion Collisions

We study the effects of a bubble configuration in a nucleus on heavy-ion collisions at a few tens and hundreds A MeV. We first investigate the bubble structure of 206Hg using the relativistic continuum Hartree–Bogoliubov theory and then study the 206Hg + 208Pb and 206Hg+206Hg reactions using the DaeJeon–Boltzmann–Uehling–Uhlenbeck (DJBUU) transport model. To see the role of the bubble structure, we consider the maximum density of the produced nuclear matter, directed flow of neutrons and protons, and π−/π+ ratio. We observe that the maximum density is smaller with a bubble nucleus, and the directed flow of nucleons and π−/π+ ratio may depend on the bubble structure.

F1FO ATP synthase molecular motor mechanisms.

The F-ATP synthase, consisting of F1 and FO motors connected by a central rotor and the stators, is the enzyme responsible for synthesizing the majority of ATP in all organisms. The F1 (αβ)3 ring stator contains three catalytic sites. Single-molecule F1 rotation studies revealed that ATP hydrolysis at each catalytic site (0°) precedes a power-stroke that rotates subunit-γ 120° with angular velocities that vary with rotational position. Catalytic site conformations vary relative to subunit-γ position (βE, empty; βD, ADP bound; βT, ATP-bound). During a power stroke, βE binds ATP (0°–60°) and βD releases ADP (60°–120°). Årrhenius analysis of the power stroke revealed that elastic energy powers rotation via unwinding the γ-subunit coiled-coil. Energy from ATP binding at 34° closes βE upon subunit-γ to drive rotation to 120° and forcing the subunit-γ to exchange its tether from βE to βD, which changes catalytic site conformations. In F1FO, the membrane-bound FO complex contains a ring of c-subunits that is attached to subunit-γ. This c-ring rotates relative to the subunit-a stator in response to transmembrane proton flow driven by a pH gradient, which drives subunit-γ rotation in the opposite direction to force ATP synthesis in F1. Single-molecule studies of F1FO embedded in lipid bilayer nanodisks showed that the c-ring transiently stopped F1-ATPase-driven rotation every 36° (at each c-subunit in the c10-ring of E. coli F1FO) and was able to rotate 11° in the direction of ATP synthesis. Protonation and deprotonation of the conserved carboxyl group on each c-subunit is facilitated by separate groups of subunit-a residues, which were determined to have different pKa’s. Mutations of any of any residue from either group changed both pKa values, which changed the occurrence of the 11° rotation proportionately. This supports a Grotthuss mechanism for proton translocation and indicates that proton translocation occurs during the 11° steps. This is consistent with a mechanism in which each 36° of rotation the c-ring during ATP synthesis involves a proton translocation-dependent 11° rotation of the c-ring, followed by a 25° rotation driven by electrostatic interaction of the negatively charged unprotonated carboxyl group to the positively charged essential arginine in subunit-a.

Proton coupling and the multiscale kinetic mechanism of a peptide transporter

Proton-coupled peptide transporters (POTs) are crucial for the uptake of di- and tripeptides as well as drug and prodrug molecules in prokaryotes and eukaryotic cells. We illustrate from multiscale modeling how transmembrane proton flux couples within a POT protein to drive essential steps of the full functional cycle: 1) protonation of a glutamate on transmembrane helix 7 (TM7) opens the extracellular gate, allowing ligand entry; 2) inward proton flow induces the cytosolic release of ligand by varying the protonation state of a second conserved glutamate on TM10; 3) proton movement between TM7 and TM10 is thermodynamically driven and kinetically permissible via water proton shuttling without the participation of ligand. Our results, for the first time, give direct computational confirmation for the alternating access model of POTs, and point to a quantitative multiscale kinetic picture of the functioning protein mechanism.

Kinetic simulation of electron, proton and helium acceleration in a non-relativistic quasi-parallel shock

ABSTRACT In addition to accelerating electrons and protons, non-relativistic quasi-parallel shocks are expected to possess the ability to accelerate heavy ions. The shocks in supernova remnants are generally supposed to be accelerators of Galactic cosmic rays, which consist of many species of particles. We investigate the diffusive shock acceleration of electrons, protons and helium ions in a non-relativistic quasi-parallel shock through a 1D particle-in-cell simulation with a helium-to-proton number density ratio of 0.1, which is relevant for Galactic cosmic rays. The simulation indicates that waves can be excited by the flow of energetic protons and helium ions upstream of a non-relativistic quasi-parallel shock with a sonic Mach number of 14 and an Alfvén Mach number of 19.5 in the shock rest frame, and that the charged particles are scattered by the self-generated waves and accelerated gradually. Moreover, the spectra of the charged particles downstream of the shock are thermal with a non-thermal tail, and the acceleration is efficient, with about $7{{\ \rm per\ cent}}$ and $5.4{{\ \rm per\ cent}}$ of the bulk kinetic energy transferred into the non-thermal protons and helium ions, respectively, in the near downstream region by the end of the simulation.