Ionization Of Water Molecules Research Articles

Phase-separated super-enhancers confer an innate radioresistance on genomic DNA.

Recently, biomolecular condensates formed through liquid-liquid phase separation have been widely reported to regulate key intracellular processes involved in cell biology and pathogenesis. BRD4 is a nuclear protein instrumental to the establishment of phase-separated super-enhancers (SEs) to direct the transcription of important genes. We previously observed that protein droplets of BRD4 became hydrophobic as their size increase, implying an ability of SEs to limit the ionization of water molecules by irradiation. Here, we aim to establish if SEs confer radiation resistance in cancer cells. We established an in vitro DNA damage assay that measures the effect of radicals provoked by the Fenton reaction on DNA integrity. This revealed that DNA damage was markedly reduced when BRD4 underwent phase separation with DNA. Accordingly, co-focal imaging analyses revealed that SE foci and DNA damage foci are mutually exclusive in irradiated cells. Lastly, we observed that the radioresistance of cancer cells was significantly reduced when irradiation was combined with ARV-771, a BRD4 de-stabilizer. Our data revealed the existence of innately radioresistant genomic regions driven by phase separation in cancer cells. The disruption of these phase-separated components enfolding genomic DNA may represent a novel strategy to augment the effects of radiotherapy.

DISCUSSION OF THE MECHANISM OF THE ELECTRICAL CONDUCTIVITY OF PURE WATER IN THE FRAMEWORK OF THE BJERRUM MODEL

An alternative mechanism of electrical conductivity and ionization of molecules in pure water is considered. Calculation of the temperature dependence for the activation energy of ionization of water molecules was carried out using data on the value of its ionic product. The calculated activation energies for the ionization and flow processes show the presence of a certain proportionality between them. This suggests that the ionization of water is caused by intermolecular forces rather than intramolecular forces. Accordingly, the electrical conductivity of water is associated with the appearance and movement in it of L and D defects of hydrogen bonds between water molecules, which have significant electrical pseudo charges and are considered in the Bjerrum model for ice. This work proposes a new interpretation of the mechanism of ionization (pseudoionization) of molecules and generation of L and D defects in water. Rotation is considered not for one, but for two of its molecules in opposite directions with partial compensation of their angular momentum, and the breaking of not three bonds for one molecule, but four bonds with neighbors for two molecules. Moreover, these four neighbors do not include molecules from water clusters that have stronger bonds, since neighboring molecules with weaker bonds can be found for the process of rotation activation. Accordingly, the exponential contribution made by molecules from water clusters is absent or small in the ionization activation energy. In this way, the activation energy for the flow, which occurs throughout the entire volume of the liquid and automatically includes molecules from clusters, differs from the activation energy of electrical conductivity, which occurs for individual molecules in chains of bonds. The presence of a maximum in the ionic product of water near 250 ⁰C can be explained by the rapid decrease in the lifetime of L and D defects with heating, which prevents the use of the standard equation for accurate calculation of the ionization activation energy above 100...200 ⁰C. However, the presence of this maximum contradicts the generally accepted model of proton hopping between neighboring hydronium and water molecules in the mechanism of its electrical conductivity.

Size reduction and water dispersibility improvement of hexagonal boron nitride particles by femtosecond laser irradiation in water

Controlling the size and surface state of inorganic particles, which strongly influence their dispersibility in solvents, is important for diverse applications. Intense femtosecond laser pulses can induce plasma formation in material–dispersed solvents and interact with both materials and solvents. In this study, femtosecond laser pulses are employed to modify hexagonal boron nitride (hBN) particles dispersed in water, with the aim of evaluating the effects of the femtosecond laser process on the size reduction and surface modification of hBN particles. Shadowgraph imaging reveals the formation of the reactive environment in hBN–dispersed water, resulting from the ionization of water molecules which leads to the generation of OH radicals. Evaluation of the hBN particle sizes suggests an overall reduction from 160 to 110 nm after 60 min of irradiation and the generation of nanodots between 5 and 10 nm in size. In addition, it is confirmed that the number of particles with higher zeta potentials increases after the samples are laser-irradiated, suggesting a change in the surface state. Consequently, the duration of hBN particle dispersion in water is significantly increased, with an improvement of at least one order of magnitude, for the laser-irradiated samples. This study presents a demonstration of the formation of a reaction field that affects hBN particles in size and dispersibility in water.

Nanodisk–like activated carbon-branched polyamine for adsorption and degradation of gaseous formaldehyde

The adsorption potential of activated carbon (AC) is determined to a large extent by an interplay between its surface functional groups and target pollutants like volatile organic compounds (VOCs). Herein, we present a new approach to improve such property through the creation of nanodisk-like material by modifying the surface and morphology of AC with branched polyamine (BPA). The formulated AC-BPA possesses large number of surface functional moieties (e.g., amine, –COOH, –OH, and Cl−) to facilitate physical, chemical, and reactive adsorption to tackle a common air pollutant such as formaldehyde (FA). Despite its reduction in surface area (relative to AC), AC-BPA was demonstrated to have a significantly large potential for reactive adsorption and catalytic oxidation (RACO) against FA with high adsorption capacity (82.3 mg g−1) and partition coefficient (PC = of 0.64 mol kg−1 Pa−1) under dry condition. Interestingly, a noticeable enhancement in its performance is attained by the presence of moisture (e.g., 100 % RH) as evidenced by adsorption capacity of 144.3 mg g−1 (PC of 1.25 mol kg−1 Pa−1). This can be attributed to its rich heteroatom content (e.g., COO− and Cl−), possibly inducing partial ionization of water molecules and generating secondary active sites for FA adsorption. In-situ diffuse reflectance infrared Fourier-transform spectroscopy revealed that AC-BPA catalyzed the chemical transformation of FA into methylol adducts, H2O, and CO2. These findings indicate that FA adsorption is primarily influenced by surface functional groups rather than by surface area. This study is expected to pave the way for designing metal-free high-performance RACO materials against FA under ambient conditions.

Electron and positron impact differential cross sections for the (e,2e) process on water molecule

We present a theoretical study for electron and positron-impact ionization of water molecule by using the three-body formalism of distorted-wave approximation. In this approximation, the final state contains one-Coulomb, two-Coulomb, and three-Coulomb distortion due to pairwise Coulombic interactions, respectively. In the entrance channel, the initial state is a product of two wavefunctions: the first one for the incident electron/positron described by a Coulomb wave and the second one for the ten bound electrons. The molecular wavefunction for these bound electrons of H2O are described by the linear combination of atomic orbitals. We investigate the angular distribution of the triple differential cross section (TDCS) for single ionization of the outer orbitals 1b1,3a1,1b2, and 2a1. The structure with two peaks around the binary and recoil region are clearly observed for 1b1, 3a1, and 1b2 orbitals. At the same time, a single peak in the binary region with no recoil peak is found for the 2a1 orbital. The present TDCS results are compared with available experimental and theoretical findings. Fair agreement regarding the structure of angular profile of the TDCS is observed for all orbitals except 2a1. Finally, an enhanced TDCS have been found for positron impact compared to the electron impact.

Electron impact single ionization TDCS of H2O at 81 eV for coplanar asymmetric emission of electrons

We report the results of triple differential cross section (TDCS) for the electron impact single ionization of water molecules at incident electron energy 81 eV for coplanar asymmetric emission of electrons. The TDCS results have been obtained in distorted wave second Born approximation using orientation averaged molecular orbital (OAMO) approximation. The TDCS results have been calculated for the ionization of 1b1 and 3a1 molecular orbital of water molecules for the coplanar asymmetric emission of electrons. The obtained theoretical TDCSs are compared with the available measurements as well as with the first Born results. The second Born results are found to be significant by improving agreement with the measurements particularly in the binary peak region.

Radiation damage by extensive local water ionization from two-step electron-transfer-mediated decay of solvated ions

Biomolecular radiation damage is largely mediated by radicals and low-energy electrons formed by water ionization rather than by direct ionization of biomolecules. It was speculated that such an extensive, localized water ionization can be caused by ultrafast processes following excitation by core-level ionization of hydrated metal ions. In this model, ions relax via a cascade of local Auger–Meitner and, importantly, non-local charge- and energy-transfer processes involving the water environment. Here, we experimentally and theoretically show that, for solvated paradigmatic intermediate-mass Al3+ ions, electronic relaxation involves two sequential solute–solvent electron transfer-mediated decay processes. The electron transfer-mediated decay steps correspond to sequential relaxation from Al5+ to Al3+ accompanied by formation of four ionized water molecules and two low-energy electrons. Such charge multiplication and the generated highly reactive species are expected to initiate cascades of radical reactions.

Superoxide Production under Soft X-ray Irradiation of Liquid Water

Soft X-rays behave like particles with high linear energy transfer, as they deposit a large amount of their energy in the nanometric range, triggered by inner-shell ionization. In water, this can lead to the formation of a doubly ionized water molecule (H2O2+) and the emission of two secondary electrons (photoelectron and Auger electron). Our focus lies on detecting and quantifying the superoxide (HO2°) production via the direct pathway, i.e., from the reaction between the dissociation product of H2O2+, i.e., the oxygen atom (∼4 fs), and the °OH radicals present in the secondary electron tracks. The HO2° yield for 1620 eV photons, via this reaction pathway, was found to be 0.005 (±0.0007) μmol/J (formed within the ∼ps range). Experiments were also performed to determine the yield of HO2° production via another (indirect) pathway, involving solvated electrons. The indirect HO2° yield, measured experimentally as a function of photon energy (from 1700 to 350 eV), resulted in a steep decrease at around 1280 eV and a minimum close to zero at 800 eV. This behavior in contradiction with the theoretical prediction reveals the complexity hidden in the intratrack reactions.

The Effect of Taheri Consciousness Fields on the ATP Production in HEK-293 Cell Line by Measuring Luciferase Activity

Various T-Consciousness Fields with different functions have been introduced by Mohammad Ali Taheri. Not only has the existence of these fields been investigated in the initial phase through various experiments, but also the empirical evidence of Mohammad Ali Taheri’s theories, such as the existence of the “mind in the matter”, has been observed. This study aimed to explore the effect of Taheri Consciousness Fields (TCFs) 1, 2, and 3 in the production process of ATP or biological energy in the human cell lines. In this experiment, a human HEK 293 cell line was used in a cell culture medium at the 24th hour of growth. The luciferase enzyme, the concentration of ATP in the sample under the influence of TCFs and control was measured and evaluated. Our findings showed that TCF 1, 2, and 3 resulted respectively in a 5, 11 and 7-fold increase in the number of ATP molecules, compared to the control samples. Due to the limited fuel cell resources and the brief treatment time (one hour) with TCFs, this increase in ATP levels cannot be attributed to the normal cytosolic and mitochondrial glucose oxidation pathways. Thus, there seems to be an alternative pathway. It is possible that TCFs influenced the ionization of water molecules in the mitochondrial intermembrane space and led to more ATP production by maintaining the proton gradient. The factor that makes this possible is nothing but the existence of a type of mind in the cells. According to Taheri’s theory, transmitted information through TCFs has been received by the mind of the cells, and as a result, has led to the ionization of water molecules in the mitochondrial intermembrane space. In conclusion, it seems that regardless of the biological system, under the influence of TCFs, there is an alternative way to increase ATP at the immediate time, which is associated with an increase in information and a decrease in the entropy of the system.

Mesenchymal stem cells in radiation-induced lung injury: From mechanisms to therapeutic potential.

Radiotherapy (RT) is an effective treatment option for multiple thoracic malignant tumors, including lung cancers, thymic cancers, and tracheal cancers. Radiation-induced lung injury (RILI) is a serious complication of radiotherapy. Radiation causes damage to the pulmonary cells and tissues. Multiple factors contribute to the progression of Radiation-induced lung injury, including genetic alterations, oxidative stress, and inflammatory responses. Especially, radiation sources contribute to oxidative stress occurrence by direct excitation and ionization of water molecules, which leads to the decomposition of water molecules and the generation of reactive oxygen species (ROS), reactive nitrogen species (RNS). Subsequently, reactive oxygen species and reactive nitrogen species overproduction can induce oxidative DNA damage. Immune cells and multiple signaling molecules play a major role in the entire process. Mesenchymal stem cells (MSCs) are pluripotent stem cells with multiple differentiation potentials, which are under investigation to treat radiation-induced lung injury. Mesenchymal stem cells can protect normal pulmonary cells from injury by targeting multiple signaling molecules to regulate immune cells and to control balance between antioxidants and prooxidants, thereby inhibiting inflammation and fibrosis. Genetically modified mesenchymal stem cells can improve the natural function of mesenchymal stem cells, including cellular survival, tissue regeneration, and homing. These reprogrammed mesenchymal stem cells can produce the desired products, including cytokines, receptors, and enzymes, which can contribute to further advances in the therapeutic application of mesenchymal stem cells. Here, we review the molecular mechanisms of radiation-induced lung injury and discuss the potential of Mesenchymal stem cells for the prevention and treatment of radiation-induced lung injury. Clarification of these key issues will make mesenchymal stem cells a more fantastic novel therapeutic strategy for radiation-induced lung injury in clinics, and the readers can have a comprehensive understanding in this fields.

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing.

Cellulose polymer insulation material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

Different approximations in the polarization control of two-color water molecule ionization

We investigate different approximations in a polarization control scheme in two-color two-photon ionization by means of second-order time-dependent perturbation theory. Experiments revealed light-polarization dependencies in the above-threshold ionization of water molecules assisted by an IR field. These experiments were performed at photoelectron energies at which the soft-photon approximation exhibits discrepancies. We show that these discrepancies may be attributed to the coulombic nature of the scattering process for continuum–continuum transitions.

The role of negative hydroxyl ions in the electron generation and breakdown during plasma formation in liquid water

The role of negative hydroxyl ions in liquid-phase plasma discharge formation is investigated using an inhouse modeling framework. Two tunneling sources for electrons are considered—tunneling ionization of water molecules and tunneling detachment of negative hydroxyl ions together with additional reaction steps. The simulations are conducted for a needle-like powered electrode with two different nanosecond rise time voltage profiles—a linear and an exponential rise. Both the profiles have a maximum voltage of 15 kV. The predictions show that the electron detachment, which has a much lower threshold energy requirement, provides a stream of electrons at low applied voltage during the initial rise time. The electrical forces from the electron detachment process generate stronger compression but a weaker expansion regime in the liquid resulting in ∼40% increase in the density and only ∼1% decrease. The electron detachment tunneling process is found to be not limited by the electric field, but rather by the availability of negative hydroxyl ions in the system and ceases when these ions are depleted. The tunnel ionization of water molecules forms the electron wave at a higher applied voltage, but the resulting peak electron number density is typically six orders of magnitude larger than the detachment tunneling. The higher electron number density allows the recycling of depleted negative hydroxyl ions in the system and can reestablish tunneling detachment. In addition, the system experiences a larger variation in density; specifically, a decrease in density due to tunnel ionization. The prediction also shows that irrespective of the initial electron sources (i.e. tunnel ionization or tunnel detachment) the reduced electric field is not sufficient enough to allow electron impact ionization to be active and make a significant contribution. Path flux analysis is conducted to determine the kinetics responsible for the recycling of the negative hydroxyl ions.

Electron generation and multiplication at the initial stage of nanosecond breakdown in water

Electrical breakdown of liquid dielectrics under nanosecond pulsed high voltage has been investigated extensively in the last decade. Prior studies have focused on either experimental characterization of the breakdown process and discharge plasma or formulation/verification of the electrostrictive cavitation mechanism of the breakdown initiation. There remain knowledge gaps toward a clear physical picture of how the first plasma is generated in a region saturated by nanoscale cavities created by electrostrictive forces in inhomogeneous fields at the nanosecond timescale. Initial plasma results from the multiplication of primary electrons that gain energy collisionlessly in the cavities to cause collisional ionization of water molecules on the cavity walls. This paper quantitatively discusses the possible sources of primary electrons that seed the plasma discharge. Electron detachment from hydroxide is shown to be the most probable and sustainable electron source. Using numerical modeling, this study demonstrates the plausibility of an electron multiplication mechanism involving two neighboring cavities. The drift of hydrated electrons from one cavity to the next is the rate-limiting step and sets the minimum electric field requirement. This work will inform subsequent experimental studies and have implications in various applications such as plasma sources in biomedical applications, cavitation study, and insulation of pulsed power equipment.

Initiation of nanosecond-pulsed discharge in water: Electrostriction effect

Underwater nanosecond-pulsed discharges have been widely utilized in numerous industrial applications. The initial stage of nanosecond-pulsed discharge in water contains extremely abundant physical processes, however, it is still difficult to reveal the details of charge transportation and multiplicative process in liquid within several nanoseconds by currently existing experimental diagnostic techniques. Up to now, the initiation mechanism of underwater nanosecond discharge has been still a puzzle. In this paper, we develop a two-dimensional axially symmetric underwater discharge model of pin-to-plane, and numerically investigate the electrostriction process, cavitation process, and ionization process in water, induced by nanosecond-pulsed voltage. The negative pressure in water caused by tensile ponderomotive force is calculated. The creation of nanoscale cavities (so-called nanopores) in liquid due to negative pressure is modeled by classical nucleation theory with modified nucleation energy barrier. When estimating the temporal development of nanopore radius, a varying hydrostatic pressure is considered to restrain the unlimited expansion of nanopores. We estimate the electron generation rate by the product of the generation rate of incident electrons and the number density of nanopores. The simulation results show that cavitation occurs in liquid within several microns from pin electrode due to the electrostriction, which results in the formation of a large number of nanopores. The expansion of nanopore, caused by electrostrictive pressure on nanopore surface, provides a sufficient acceleration distance for electrons. The impact ionization of water molecules can be triggered by energetic electrons, leading the local liquid to be ionized rapidly. The effects of nanopores on rapid electron generation in water are discussed. Once nanopores are formed, the electrons can be generated in the following ways: 1) Field ionization of water molecules on the nanopore wall continuously provides seed electrons; 2) the seed electrons accelerated in nanopores enter into the liquid and collide with water molecules, resulting in the rapid increase of electrons. It can be inferred that the randomly scattered nanopores act as micro-sources of charges that contribute to the continuing ionization of liquid water in cavitation region near pin electrode. Electrostriction mechanism provides a new perspective for understanding the initiation of nanosecond-pulsed discharge in water.

Nanosecond pulsed discharges in distilled water: I. Continuum radiation and plasma ignition

Nanosecond plasmas in liquids are an important method to trigger the water chemistry for electrolysis or for biomedical applications in plasma medicine. The understanding of these chemical processes relies on knowing the variation of the temperatures in these dynamic plasmas. This is analyzed by monitoring nanosecond pulsed plasmas that are generated by high voltages at 20 kV and pulse lengths of 15 ns applied to a tungsten tip with 50 μm diameter immersed in water. Plasma emission is analyzed by optical emission spectroscopy ranging from UV wavelengths of 250 nm to visible wavelengths of 850 nm at a high temporal resolution of 2 ns. The spectra are dominated by the black body continuum from the hot tungsten surface and line emissions from the hydrogen Balmer series. Typical temperatures from 6000 K up to 8000 K are reached for the tungsten surface corresponding to the boiling temperature of tungsten at varying tungsten vapor pressures. The analysis of the ignition process and the concurrent spectral features indicate that the plasma is initiated by field ionization of water molecules at the electrode surface. At the end of the pulse, field emission of electrons can occur. During the plasma pulse, it is postulated that the plasma contracts locally at the electrode surface forming a hot spot. This causes a characteristic contribution to the continuum emission at small wavelengths.

Field-Induced Tunneling Ionization and Terahertz-Driven Electron Dynamics in Liquid Water.

Liquid water at ambient temperature displays ultrafast molecular motions and concomitant fluctuations of very strong electric fields originating from the dipolar H2O molecules. We show that such random intermolecular fields induce the tunnel ionization of water molecules, which becomes irreversible if an external terahertz (THz) pulse imposes an additional directed electric field on the liquid. Time-resolved nonlinear THz spectroscopy maps charge separation, transport, and localization of the released electrons on a few-picosecond time scale. The highly polarizable localized electrons modify the THz absorption spectrum and refractive index of water, a manifestation of a highly nonlinear response. Our results demonstrate how the interplay of local electric field fluctuations and external electric fields allows for steering charge dynamics and dielectric properties in aqueous systems.

Energetics of Ionized Water Molecules in the H-Bond Network near the Ca2+ and Cl- Binding Sites in Photosystem II.

In photosystem II, water oxidation occurs at the oxygen-evolving complex (OEC). The presence of a hydronium ion (H3O+) was proposed at the Cl- binding site and Ca2+-depleted OEC. Using a quantum mechanical/molecular mechanical approach, we report the stability of H3O+ in the PSII protein environment. Neither release of the proton from ligand water molecule W2 at the OEC nor formation of H3O+ at Cl- is energetically favorable. In contrast, H3O+ can exist at the Ca2+-depleted OEC. Even when H3O+ exists in Ca2+-depleted PSII, the H-bond network of the redox-active tyrosine (TyrZ) remains unaltered, retaining the unusually short low-barrier H-bond with D1-His190, and the redox potential of TyrZ, Em(TyrZ), remains unaltered. These observations explain why the oxidation of the Ca2+-depleted Mn4O5 cluster by TyrZ (i.e., the S2 to S3 transition) is not inhibited at low pH. It seems likely that Ca2+ plays a role in not only (i) maintaining the H-bond network and facilitating TyrZ oxidation [tuning Em(TyrZ)] but also (ii) providing the valence of +2, decreasing the pKa of the ligand molecule (W1), and facilitating the release of the proton from W1 in the S2 to S3 transition together with Cl-.

Chemical Analysis of Secondary Electron Emission from a Water Cathode at the Interface with a Nonthermal Plasma.

When a nonthermal plasma and a liquid form part of the same circuit, the liquid may function as a cathode, in which case electrons are emitted from the liquid into the gas to sustain the plasma. As opposed to solid electrodes, the mechanism of this emission has not been established for a liquid, even though various theories have attempted to explain it via chemical processes in the liquid phase. In this work, we tested the effects of the interfacial chemistry on electron emission from water, including the role of pH as well as the hydroxyl radical, the hydrogen atom, the solvated electron, and the presolvated electron; it was found that none of these species are critical to sustain the plasma. We propose an emission mechanism where electrons, generated from ionized water molecules in the uppermost monolayers of solution, are emitted into the plasma directly from the conduction band of the water.

Water molecule ionization by proton impact experiment and GTO-First Born theory

SynopsisIn this communication we present calculations and measurements of water ionization by protons at intermediate and high impact energies. The main goal of the present theoretical approach is the development of a method to routinely incorporate sophisticated wavefunctions for small and medium-sized molecules in the determination of ionization cross-sections.