Charge Shift Research Articles

Defect-Rich PdIr Bimetallene Nanoribbons with Interatomic Charge Localization for Isopropanol-Assisted Seawater Splitting.

Metallene with outstanding physicochemical properties is an efficient two-dimensional electrocatalysts for sustainable hydrogen (H2 ) production applications. However, the controllable fabrication of extended atomically thin metallene nanoribbons remains a formidable challenge. Herein, this work proposes a controllable preparation strategy for atomically thin defect-rich PdIr bimetallene nanoribbons (PdIr BNRs) with a thickness of only 1.5nm for the efficient and stable isopropanol-assisted seawater electrolytic H2 production. When using PdIr BNRs as catalyst to build an isopropanol-assisted seawater electrolysis system, a voltage of only 0.38V is required at @10mA cm-2 to achieve energy-saving H2 production, while producing high value-added acetone at the anode. The aberration-corrected high-resolution transmission electron microscopy (HRTEM) clearly reveals that the PdIr BNRs possess abundant structural defects, which can additionally serve as highly catalytically active sites. Density functional theory (DFT) calculations combined with X-ray absorption spectroscopy studies reveal that the introduction of Ir atoms can induce the formation of a localized charge region and shift the d-band center of Pd down, thereby reducing the adsorption energy on the catalyst in favor of the rapid desorption of H2 . This work opens the way for the controllable design and construction of defect-rich atomically thin metallene nanoribbons for efficient electrocatalytic applications.

Biochemical composition and adenylate energy charge shifts in longfin yellowtail (Seriola rivoliana) embryos during development under different temperatures

The longfin yellowtail Seriola rivoliana is an emerging species for aquaculture diversification worldwide and production relies on fertilized eggs from captive broodstock. Temperature is the main factor that influences the developmental process and success during fish ontogeny. However, the effects of temperature on the utilization of the main biochemical reserves and bioenergetics are scarcely investigated in fish, whereas protein, lipid and carbohydrate metabolism have critical roles in maintaining cellular energy homeostasis. In this context, we aimed to evaluate metabolic fuels (protein, lipids, triacylglicerides, carbohydrates), adenylic nucleotides and derivates (ATP, ADP, AMP, IMP), and the adenylate energy charge (AEC) during embryogenesis and in hatched larvae in S. rivoliana at different temperatures. For this purpose, fertilized eggs were incubated at six constant (20, 22, 24, 26, 28 and 30 °C) and two oscillating (21⇄29 °C) temperatures. Biochemical analyses were made at blastula, optic vesicles, neurula, prehatch and hatch periods. Results indicated that the developmental period had a major influence on the biochemical composition at any temperature regime tested during the incubation. Protein content decreased only at hatching mainly due to the loss of the chorion, total lipids tended to increase at the neurula period and variations in carbohydrates depended on the particular spawn analyzed. Triacylglicerides were a critical egg fuel during hatching. The high AEC during embryogenesis and even in hatched larvae suggested an optimal energy balance regulation. The lack of critical biochemical changes from different temperature regimes during embryo development confirmed that this species exhibits a high adaptive capacity in response to constant and fluctuating temperatures. However, the timing of hatching was the most critical period of development, where biochemical components and energy utilization significantly changed. The oscillating temperatures tested may have physiological advantages without detrimental energetic effects that will require further research on larval quality after hatching.

The impact of initial working fluid charge on performance of Organic Rankine Cycle using zeotrope mixture under design condition

Mass-based analysis of thermodynamic cycle can be a link to realize the matching between the fluid properties, components performance, and operation parameters. The present paper proposes a mass-based analysis for ORC systems using zeotropic fluid mixture, focusing on evaporator and condenser as the phase-change heat transfer components. This proves to be an effective way to investigate the impact of composition shift and the initial working fluid charge on system design performance. Results indicated that liquid-phase zones in both heat exchangers account for about 60 % of total mass. Since the largest composition shift occurs in condensation zone, this relation affects the masses and composition shifts in other zones as well as the overall system. Meanwhile, the relationship between the initial charge and composition shift are analyzed. It is found that the increase of total mass leads to a decrease of mass in two-phase zones and an increase of mass in single-phase zones. It therefore causes a reduction of the average composition shift. Moreover, analysis shows the highest net output work of 2.34 kW, which occurs when the initial working fluid charge rises to 130 % of the design value. However, further increases in mass will have a negative impact on system performance.

Bonding and the role of electrostatics in driving C-C bond formation in high valent organocopper compounds.

The electronic structures and contrasting reactivity of [Cu(CF3)4]- and [Cu(CF3)3(CH3)]- were probed using coupled cluster and ab initio valence bond calculations. The Cu-C bonds in these complexes were found to be charge shift bonds. A key finding is that electrostatics likely prevent [Cu(CF3)4]- from accessing a productive transition state for C-C bond formation while promote one for [Cu(CF3)3(CH3)]-. These results therefore highlight essential design criteria for Cu-mediated C-C/C-heteroatom bond formation.

Fractional Disclination Charge and Discrete Shift in the Hofstadter Butterfly.

In the presence of crystalline symmetries, topological phases of matter acquire a host of invariants leading to nontrivial quantized responses. Here we study a particular invariant, the discrete shift 𝒮, for the square lattice Hofstadter model of free fermions. 𝒮 is associated with a Z_{M} classification in the presence of M-fold rotational symmetry and charge conservation. 𝒮 gives quantized contributions to (i)the fractional charge bound to a lattice disclination and (ii)the angular momentum of the ground state with an additional, symmetrically inserted magnetic flux. 𝒮 forms its own "Hofstadter butterfly," which we numerically compute, refining the usual phase diagram of the Hofstadter model. We propose an empirical formula for 𝒮 in terms of density and flux per plaquette for the Hofstadter bands, and we derive a number of general constraints. We show that bands with the same Chern number may have different values of 𝒮, although odd and even Chern number bands always have half-integer and integer values of 𝒮, respectively.

The effect of immediate environment on bond strength of different bond types-A valence bond study.

The ability to design catalysis largely depends on our understanding of the electrostatic effect of the surrounding on the bonds participating in the reaction. Here, we used a simplistic model of point charges (PCs) to determine a set of rules guiding how to construct PC-bond arrangement that can strengthen or weaken different chemical bonds. Using valence bond theory to calculate the in situ bond energies, we show that the effect of the PC mainly depends on the bond's dipole moment irrespective of its type (being covalent or charge shift). That is, polar bonds are getting stronger or weaker depending on the signand location of the PC, whereas non- or weakly polar bonds become stronger or weaker depending only on the location of the PC and to a smaller extent compared with polar bonds. We also show that for polar bonds, the maximal bond strengthening and weakening effect can be achieved when the PC is placed along the bond axis, as close as possible to the more and less polarizable atom/fragment, respectively. Finally, due to the stabilizing effects of polarizability, we show that, overall, it is easier to cause bond strengthening compared with bond weakening. Particularly, for polar bonds, bond strengthening is larger than bond weakening obtained by an oppositely signed PC. These rules should be useful in the future design of catalysis in, e.g., enzyme active sites.

Electron acceptor, excitation energies, oscillatory strength, spectroscopic and solvent effects on 5-amino-4,6-dichloro-2-(propylthio) pyrimidine - anticancer agent

The characteristics of Five-amino-4,6-dichloro-2-(propylthio) pyrimidine (5ADCPP) are studied using theoretical vibrational spectroscopic techniques including spectroscopy in the FT-IR, FT-Raman, and UV–Visible ranges. Raman scattering, infrared penetration intensities, vibrational modes, and the optimized geometric figure make use of the theory of density functionals (DFT). The HOMO and LUMO molecular orbitals indicate the molecule underwent an excellent shift in charge. The NBO approach was used to study the relationships between donors and recipients. Topological studies are carried out with AIM theory and LOL and ELF studies are done on the molecule. The hyperpolarizability calculation indicates that the 5ADCPP has excellent NLO properties. By using UV–Vis studies at different solvents the electronic transition is obtained. Fukui function and molecular electrostatic potential (MEP) research are covered. Drug-likeness has been carried out. The target proteins and the ligand 5ADCPP are used in molecular docking to get the cancer-preventive action.

Gold(I)···Lanthanide(III) Bonds in Discrete Heterobimetallic Compounds: A Combined Computational and Topological Study.

The chemical nature of the ligand-unsupported gold(I)-lanthanide(III) bond in the proposed [LnIII(η5-Cp)2][AuIPh2] (Ln-Au; LnIII = LaIII, EuIII, or LuIII; Cp = cyclopentadienide; Ph = phenyl) models is examined from a theoretical viewpoint. The covalent bond-like Au-Ln distances (Au-La, 2.95 Å; Au-Eu, 2.85 Å; Au-Lu, 2.78 Å) result from a strong interaction between the oppositely charged fragments (ΔEintMP2 > 600 kJ mol-1), including the aforementioned metal-metal bond and additional LnIII-Cipso and C-H···π interactions. The Au-Ln bond has been characterized as a chemical bond rather than a strong metallophilic interaction with the aid of energy decomposition analysis, interaction region indicator, and quantum theory of atoms in molecules topological tools. The chemical nature of the Au-Ln bond cannot be fully ascribed to a covalent or an ionic model; an intermediate situation or a charge shift bond is proposed. The [AuIPh2]- anion has also been identified as a suitable lanthanide(III) emission sensitizer for La-Au and Lu-Au.

Modeling the Effect of H-Bonding of Excited Quadrupolar Molecules with a Solvent on Charge Transfer Symmetry Breaking.

A model of the H-bonding effect on charge transfer symmetry breaking in excited quadrupolar dyes is proposed. A dye is assumed to have two symmetrically arranged H-bond acceptors. The effect of H-bonding is described in terms of two quantities: (i) the free energy of H-bond formation by an excited symmetric dye with a protic solvent and (ii) a parameter that determines the susceptibility of the H-bond strength to the charge of the H-bond acceptor. The model assumes that an increase in dye dissymmetry results in a charge shift from one acceptor to the other, making one acceptor more negative and the other less negative. As a result, the strength of the H-bond on one branch increases, while on the other branch, it decreases. An analytical solution of the mathematical model is obtained. Regardless of the strength of the H-bond, the effect of the H-bonding on the symmetry breaking degree is shown to be small, as long as the free energy of formation of the weaker H-bond is negative. A strong effect is expected only if this free energy becomes positive, that is, when the H-bond is formed on only one arm. An unexpected result of weakening of the dissymmetry degree caused by the strengthening of the H-bond is predicted and discussed. An approach for quantitative determination of the susceptibility of the H-bond strength to the charge of the H-bond acceptor is proposed.

Characteristics of organic titanate modified titanium dioxide nanoparticles and its dispersibility in acrylic emulsion coating

AbstractThis work presents the characteristics of rutile TiO2 nanoparticles modified by isopropyl tri[di(octyl) phosphato] titanate (KR‐12) with the content of 3, 5 and 10 wt.% as compared to TiO2 nanoparticles weight. The infrared (IR) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), and thermal gravimetry analysis (TGA) methods were used to evaluate the surface modification efficiency of the TiO2 nanoparticles with KR‐12. The TGA and IR analysis results indicated that the organic coupling agent (KR‐12) was grafted to the surface of the nanoparticles. The TiO2 nanoparticles after modification could disperse stably in water easily. The modification caused the shift of surface charge of the TiO2 nanoparticles to more positive region. The average particle size of TiO2 nanoparticles modified with 0, 3, 5, and 10 wt.% of KR‐12 was 443.9 nm, 295.3 nm, 334.8 nm, and 392.3 nm, respectively. The hydrophobic ability of TiO2 nanoparticles was improved significantly after modification. The modified TiO2 nanoparticles could well disperse in acrylic emulsion coating with dispersed phase size of 200‐400 nm.

Investigation on charged particles in inductively coupled Ar/O2 plasmas: The role of Ar proportion

In this paper, a 2D fluid model is built to reveal the inductively coupled Ar/O2 plasma behavior at 300 W, 30 mTorr, in the gas mixture of 95% Ar −5% O2 and 10% Ar −90% O2. The reliability of the model is first verified by comparing the calculated results with the experimental data, and the consistent results are obtained. Then, the spatial distributions of the charged species densities are investigated. As Ar fraction decreases, the maximum densities of charged particles shift toward the coil significantly, and the O2+ becomes the dominant positive ion at higher O2 fractions. The main reaction mechanisms are also discussed. It is concluded that the electrons are generated by the ionization of background gases, and the Ar+ ions are primarily formed by the ionization of Ar. However, the charge exchange processes account for the most production of O2+ and O+ ions at a high Ar fraction. The loss at the walls is the most important process to the consumption of positive ions. For the O− ions, they are first generated by the dissociative attachment of O2 at ground state, followed by the metastable state, and they are destroyed either by the ion–ion recombination with Ar+ ions or the detachment with O atoms as the Ar proportion varies. Finally, the effect of the ion–ion recombination reaction rate coefficients is discussed. The results indicate that rate coefficients of the recombination reactions have a significant influence on the positive ion densities when the Ar fractions are high.

Theoretical design and prediction of novel fluorene-based non-fullerene acceptors for environmentally friendly organic solar cell

Organic solar cells (OSCs) with electron-withdrawing cyano-group (−CN) have created massive interest by exhibiting higher efficiencies. Nevertheless, introducing the − CN group through malononitrile during their synthesis is highly toxic and harmful to the environment. Therefore, the development of environmentally friendly OSCs (EFOSCs) is of utmost importance. Taking inspiration from the recent reports, this manuscript looks to suggest more efficient novel fluorene-based EFOSCs based on DTC-T-F type molecule containing fluorene as central core and thiophene as the linker. The − CN of 2-(6-oxo-5,6-dihydro-4H-cyclopenta[c]thiophen-4-ylidene) malononitrile (TC) present as an end-capped acceptor in DTC-T-F is replaced with non-toxic electron-pulling units -CF3, -SO3H, –NO2 and a novel series developed through quantum chemical calculation of fluorene-based photovoltaic materials (C1- C9). Frontier molecular orbital, density of state, heat maps of TDM, and finally, the charge shift process is observed by blending the C3 acceptor with donor polymer PTB7-Th (HOMOPTB7-Th-LUMOC3). The designed molecules gave comparable and better results from reference C. The minimum energy gap is observed in C3, C6 and C9 molecules with 2.29 eV, 2.28 eV and 2.27 eV energy gap values respectively. The proposed C9 compound exhibits a prominent redshift in solvent (681.82 nm) and gas phase (618.88 nm). Open circuit voltage (Voc) is the key parameter while assessing the OSC efficiency. The highest Voc is possessed by C5 (2.05 V). Exciton binding energy (Eb) is computed, and C7 has the lowest value of Eb = 0.38 eV. Finally, the reorganization energy values shown by proposed molecules indicate that fluorene-based series are effective candidates for manufacturing EFOSCs. All of the data showed that the designed molecules not only have superior optoelectronic properties to those of the synthetic compound, but also possess environmentally benign properties. This theoretical understanding will provide a CNfree strategy for developing next-generation EFOSCs and novel fluorene-based environmentally friendly materials for OSCs applications.

Sandwich, Triple-Decker and Other Sandwich-like Complexes of Cyclopentadienyl Anions with Lithium or Sodium Cations.

Density functional theory, DFT, calculations were carried out on complexes containing cyclopentadienyl anions and lithium or sodium cations; half-sandwich, sandwich and sandwich-like complexes (among them triple-decker ones) are analyzed. Searches performed through the Cambridge Structural Database revealed that crystal structures containing these motifs exist, mostly structures with sodium cations. The DFT calculations performed here include geometry optimization and frequency calculations of the complexes at the ωB97XD/aug-cc-pVTZ level, followed by the partitioning of the energy of interaction via the Energy Decomposition Analysis scheme, EDA, at the BP86-D3/TZ2P level. Additional calculations and analyses were performed using both the Quantum Theory of Atoms in Molecules, QTAIM, and the Natural Bond Orbital analyses, NBO. The results of this work show that the electrostatic interaction energy is the most important attractive contribution to the total interaction energy of each of the complex systems analyzed here, and that complexation itself leads to minor electron charge shifts.

A DFT study of the adsorption of F atoms on germanene nanoribbons

In the paper, we investigate the structure and electronic properties of the pristine germanene nanoribbon and four adsorption configurations of 1F and 2F on the substrate of germanene nanoribbon. We obtained the parameters of the most stable structures of pristine germanene nanoribbon and four adsorption configurations. The band structure and the density of state and the part density of state for each element were also obtained. Findings show the adsorption configuration of 1F-GeNR.bridge has no band structure, while other configurations are semimetals with band gap from 0.175eV to 0.67eV; both four adsorption configurations are chemisorption and non-magnetic. The charge distribution of all configurations also was investigated; it showed that there is a charge shift from Ge atoms towards F atoms due to their electronegativity difference.

Investigating the Role of Novel Benzotrithiophene-Based Bat-Shaped Non-Fullerene Acceptors for High Performance Organic Solar Cells

The development of an effective building blocks considered the boon in constructing highly efficient nonfullerene electron acceptors (NFEAs). The first theoretical design and investigation of environmental-friendly groups for changing potential end-capped electron acceptor molecules for high-performance environmental-friendly OSCs is proposed in this study. We developed BTT-based [Formula: see text]–[Formula: see text]–[Formula: see text]–[Formula: see text]–[Formula: see text] (acceptor–bridge–core–bridge–acceptor) type, neoteric Bat-shaped environmental-friendly acceptor molecules (K1–K6) for the first time by replacing the electronegative –F group of BTT with four electron-withdrawing (–CN, –COOCH3, –NO2, –Cl) groups. K1–K6 has its exciton-binding energy ([Formula: see text]), open-circuit voltage ([Formula: see text]), frontier molecular orbital analysis (FMO), transition density matrix (TDM) analysis, electron and hole reorganization energy ([Formula: see text]e, [Formula: see text]h), density of state (DOS) graphs, and transition energy Ex values computed and compared to the recently proposed high-performance BTT molecule. According to the research, the photovoltaic, photo-physical and electrical applications of proposed molecules K1–K6 are comparable to those of [Formula: see text]. When compared to reference [Formula: see text] and proposed molecules, K6 tested to be the proverbial optoelectronic compound for OSCs due to its low [Formula: see text] (2.05[Formula: see text]eV), lowest [Formula: see text] (1.57[Formula: see text]eV), highest [Formula: see text] max values of 790.61[Formula: see text]nm in CHCl3, 0.95[Formula: see text]V value for [Formula: see text] and comparable [Formula: see text] (0.482[Formula: see text]eV). The superposition of orbitals and lucrative charge shift from the highest occupied molecular orbital (HOMO) (PTB7-Th) to the lowest unoccupied molecular orbital (LUMO) were verified by charge transfer study among the K6: PTB7-Th combine. As a result, the proposed molecules (K1–K6) with exceptional optoelectronic capabilities are suggested as the best harmless alternative materials for creating proficient and environmental-friendly OSCs.

U(1) CS theory vs SL(2) CS formulation: Boundary theory and Wilson line

We first derive the boundary theory from the U(1) Chern-Simons theory. The boundary action on an n-sheet manifold appears from its back-reaction of the Wilson line. The reason is that the U(1) Chern-Simons theory can provide an exact effective action when introducing the Wilson line. The Wilson line in the pure AdS3 Einstein gravity is equivalent to entanglement entropy in the boundary theory up to classical gravity. The U(1) Chern-Simons theory deviates by a self-interaction term from the gauge formulation on the boundary. We also compare the Hayward term in the SL(2) Chern-Simons formulation to the Wilson line approach. Introducing two wedges can reproduce the entanglement entropy for a single interval at the classical level. We propose quantum generalization by combining the bulk and Hayward terms. The quantum correction of the partition function vanishes. In the end, we calculate the entanglement entropy for a single interval. The pure AdS3 Einstein gravity theory shows a shift of central charge by 26 at the one-loop level. The U(1) Chern-Simons theory does not show a shift from the quantum effect. The result is the same in the weak gravitational constant limit. The non-vanishing quantum correction shows that the Hayward term is incorrect.

Pion-Induced Radiative Corrections to Neutron β Decay.

We compute the electromagnetic corrections to neutron β decay using a low-energy hadronic effective field theory. We identify new radiative corrections arising from virtual pions that were missed in previous studies. The largest correction is a percent-level shift in the axial charge of the nucleon proportional to the electromagnetic part of the pion-mass splitting. Smaller corrections, comparable to anticipated experimental precision, impact the β-ν angular correlations and the β asymmetry. We comment on implications of our results for the comparison of the experimentally measured nucleon axial charge with first-principles computations using lattice QCD and on the potential of β decay experiments to constrain beyond-the-standard-model interactions.

Computational modeling and quantitative physiology reveal central parameters for brassinosteroid-regulated early cell physiological processes linked to elongation growth of the Arabidopsis root.

Brassinosteroids (BR) are key hormonal regulators of plant development. However, whereas the individual components of BR perception and signaling are well characterized experimentally, the question of how they can act and whether they are sufficient to carry out the critical function of cellular elongation remains open. Here, we combined computational modeling with quantitative cell physiology to understand the dynamics of the plasma membrane (PM)-localized BR response pathway during the initiation of cellular responses in the epidermis of the Arabidopsis root tip that are be linked to cell elongation. The model, consisting of ordinary differential equations, comprises the BR-induced hyperpolarization of the PM, the acidification of the apoplast and subsequent cell wall swelling. We demonstrate that the competence of the root epidermal cells for the BR response predominantly depends on the amount and activity of H+-ATPases in the PM. The model further predicts that an influx of cations is required to compensate for the shift of positive charges caused by the apoplastic acidification. A potassium channel was subsequently identified and experimentally characterized, fulfilling this function. Thus, we established the landscape of components and parameters for physiological processes potentially linked to cell elongation, a central process in plant development.

A fluorescent turn-on sensor for mercury (II) ions in near neutral poly(metharylic acid) solution

The conformational change of poly (methacrylic acid) (PMAA) at various pH values is well studied; however, the application of PMAA in the field of analytical chemistry has been very limited. This investigation takes advantage of the conformational change of PMAA at various pH levels and the conformational change induced by metal ions. By adjusting the pH, thiophene-phenylanilide-acridinium molecules can serve as turn-on sensors for Hg2+ ions. In pH 7.4 buffer with PMAA molecules, the sensor is selectively turned on by Hg2+ ions to display strong charge shift state (CSH) emission at 560 nm. The intensity shows linear response to the concentration of Hg2+ ions between 0.020 mM and 0.151 mM with a detection limit in nanomolar range. The photophysical properties of sensor molecules in PMAA/mercury (II) mixture at near neutral pH are comparable to those in PMAA solution in acidic condition without mercury (II) ions. The effect of pH, temperature, polymer size, and polymer concentration on emission intensity were investigated. The sensor showed excellent percent recovery (98.4 % to 103 %) of spiked mercury (II) ions in real water samples. The sensing mechanism is likely through intrachain and interchain coordination of mercury (II) ions with the carboxyl groups on the side chain of PMAA to induce an extended coil conformation of PMAA. Calculations support the conclusion that the size and geometry of the binding sites formed inside PMAA are suitable to incorporate sensor molecules and enhance the charge shift state emission of sensor molecules.

First principles calculations of charge shift photocurrent in vdWs slide double layered 2D h-BN and β-GeS homostructures

Shift photovoltaic current (SPC) in polar non-centrosymmetric materials has recently emerged as a promising candidate for the next generation photovoltaic devices in which Shockley-Queisser limits are fully overcome. Here, we apply first-principles calculations to predict colossal SPC in the slide bilayers of 2D h-BN and β-GeS vdW homostructures. The large SPC in slide bilayers h-BN and β-GeS reaches 49.3 μAV−2 and 130 μ μAV−2, respectively, in the ultra-violet (UV) region. Increasing the number of layers is further implemented to tune the band structure of the two homostructures. Consequently, giant SPC peaks about 3 times larger than those of the bilayers are predicted at photon energies of 7.40 eV and 5.95 eV in the 5-layers of h-BN and β-GeS, respectively. The two homostructures are thus promising building blocks for next-generation photovoltaic devices. These findings also suggest layering as a possible convenient approach to enhancing and also tuning the SPC output in thin layered materials.