Increase In Charge Density Research Articles

Exploring the Electronic Influence of β‐Br Substitutions in CuTPP on Electrochemical Overall Water Splitting in Alkaline Medium

AbstractBeta substitution has a marked influence on the electronic environment of porphyrin ring atoms and the structure of the substituted porphyrin. In this work, we explore the influence of the bromo (Br) substitution at the β‐positions of copper tetraphenylporphyrin (CuTPP) and its consequent influence on the electrocatalytic alkaline overall water splitting. The β‐Br substitution is expected to exercise a strong influence on the electronic environment of central Cu through the electronic effects of Br. The overall influence of electronic effects is seen to lead to the net increase in the electron density of the central Cu (observed from XPS shifts) which is ultimately reflected in their different HER and OER performance in the alkaline medium. We observe the HER overpotentials (for 10 mA cm−2) of 697 mV, 760 mV, 838 mV, and 883 mV for the unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The OER performance on the contrary depicts the reverse order with the overpotentials of 1118 mV, 827 mV, 637 mV, and 420 mV respectively for unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The observed shifts in the catalytic performance can directly be attributed to increasing charge density on the central metal Cu2+ with the increase in the number of Br groups which in turn has opposite consequences for HER and OER performance.

Effect of Permittivity of Plasma Medium on the Particle Properties and Electric Field in a Magnetized Plasma Sheath

The plasma sheath, a thin layer having sharp gradients, is necessary to be formed at any material wall in exposure with plasma for its stability. Characteristics of magnetized plasma sheath formed in front of a material wall for different permittivity of plasma medium has been studies using the kinetic trajectory simulation (KTS) model. The electron density, ion density, electric field and potential decreases on moving away from the sheath entrance but total charge density increases. As plasma is composed of charged particles, any variation in the permittivity of the medium has significant effects on the sheath properties. It is found that on increasing the permittivity of the medium, the electric potential strength and hence electric field decreases because of increased shielding ability of the plasma. The results are in qualitative agreement with earlier studies based on the fluid approach but the kinetic approach is more accurate quantitatively providing a better perception of plasma-wall transition phenomena.

The electrophoretic motion of cylindrical macroions inside a nanochannel using molecular dynamics simulation

This paper examines the electrophoretic motion of a cylindrical macroion floating in a solution of water and NaCl inside a silicon nanochannel using molecular dynamics simulation. The aim is to investigate the effects of parameters like free movement, initial orientation, shape, aspect ratio, surface charge density and initial electrical charge of macroion on the electrophoretic motion. Findings suggest that any increase in surface charge density could give a rise to electrophoretic velocity of the solution. Considering the macroion free to move around, initial orientation does not play significant role in final results. Results also imply that macroion’s velocity does not change steadily by variations in surface charge density which is because of the multilayer structure of the Stern layer. Finally, average electrophoretic velocity of the solution for all scenarios in this study is witnessed to be the same. However, maximum electrophoretic velocity could be four times greater than average values. This must be taken into account in applications with limited maximum velocity.

Charge modifications of graphene oxide enhance the inhibitory effect on insulin amyloid fibrillation based on electrostatic interactions

Graphene oxide (GO) is a biocompatible nanomaterial that has an inhibitory effect on insulin amyloid fibrillation. In order to enhance the inhibitory effect of GO and explore the rules of electrostatic interactions on the inhibitory effect, carboxyl group, PEI and PEG were coupled to the GO nanoplatelet surface to prepare inhibitors of different surface electrical properties. The effects of surface electrical properties of inhibitors on insulin fibrillation were investigated. The results showed that GO, carboxyl group modified GO (GO-COOH), PEI modified GO (GO-PEI), and PEG modified GO (GO-PEG) inhibited insulin fibrillation in a dose-dependent manner. Compared with GO, positive charge-modified GO-PEI and negative charge-modified GO-COOH enhanced the inhibitory effect, while uncharged polymer-modified GO-PEG weakened the inhibitory effect. The inhibitory effect of the inhibitors increased with the increase of surface charge density. The difference in inhibitory effect between GO-PEI and GO-COOH was due to the different electrostatic interactions between inhibitors and insulin, and the different inhibition mechanisms. In addition, inhibitors mainly interact with insulin during the nucleation phase to hinder insulin fibrillation. The charge modifications of graphene oxide enhanced the inhibitory effect on insulin fibrillation based on electrostatic interactions, which will provide new thoughts for the development of anti-amyloid fibrillation drugs.

Synthesis and thermomechanical characteristics of zwitterionic poly(arylene ether sulfone) copolymers

Charge-containing polymeric materials have been widely studied for a range of applications. The fundamental relationships between the charge species, charge density, and the microscale morphology of charge-containing polymers are critical for defining the application in which they may be used. In this work, a series of thermoplastic poly(arylene ether sulfone) (PAES) copolymers with controllable sulfobetaine charge contents (0–100 mol%) and high molecular weights (Mw ∼ 65 kDa) were prepared. All the zwitterionic PAESs synthesized showed thermal stability up to 250 °C. DSC and tensile tests showed a decreased Tg and mechanical strength with the incorporation of increasing charge density, which suggests a plasticization effect by the charged group. Electron microscopy and X-ray scattering data confirmed the absence of microphase separation in the ion-containing random copolymer system, which corroborated with the observation of a single Tg for all zwitterionic copolymers studied. Furthermore, the relative hydrophilicity of the samples was evaluated by water uptake measurements, which revealed that the water uptake of the zwitterionic PAESs can reach up to 64% for the 72 mol% zwitterion copolymer while the free-standing film in the wet state still maintains a Young's modulus of 185 MPa. The thermoplastic charge-containing copolymers in this work demonstrated potential for applications such as coatings or water purification membranes, in which balancing hydrophilicity, processibility, and thermomechanical performance are important.

Effect of layer charge density and cation concentration on sorption behaviors of heavy metal ions in the interlayer and nanopore of montmorillonite: A molecular dynamics simulation

Soil and ground water pollution by heavy metal is an identified global environment concern. Montmorillonite is widely adopted as an adsorbent used in retardation of heavy metals due to its excellent adsorption capacity, conveniency, and stability. However, the adsorption mechanism of heavy metal ions in the interlayer and nanopore of montmorillonite needs to be further studied. The classical grand canonical monte carlo (GCMC) and molecular dynamics (MD) simulations were performed to quantify the structural and dynamic properties of heavy metal ions in the interlayer and nanopore of montmorillonite (MMT). Two layer charge densities of MMT, two cation concentrations, and three typical heavy metal ions (Pb2+, Ba2+, and Cs+) were considered. With the increase of layer charge density, outer-sphere adsorption (OSA) was transformed into inner-sphere adsorption (ISA) for three heavy metal ions. The adsorption quantity increased with the increase of layer charge density and cation concentration. The calculated diffusion coefficients of three heavy metal caions in montmorillonite was bulk solution > nanopore > interlayer. The results and adsorption mechanism are helpful for understanding the natural processes of heavy metal ions in environment and developing more efficient remediation materials.

Dynamic interplay between thionine and DNA under carbon ion irradiation: a real-time first-principles study

Understanding the interactions between deoxyribonucleic acid (DNA) and photosensitizer under ion irradiation benefits the development of aptasensors, DNA biosensors and cancer diagnosis. Using real-time time-depended density functional theory, by simulating high-energy C ion passing through DNA with poly(dG)·poly(dC) sequence and that with embedded thionine (3,7-diamino-5-phenothiazinium, TH), we compared the electronic stopping power (ESP), evolution of the structure and charge, and absorption spectrum. TH inserting leads the increase in space charge density, a larger electron de-excitation and a larger ESP, but the speed corresponding to the maximum ESP is almost same. When C ion passes through TH–DNA, the structure of TH slightly changes and there still exists noncovalent interaction between TH and DNA, but the absorption coefficient depends on the electron occupied state of TH when the ion passes through. These results indicate that at low radiation doses, TH still can be a DNA detector, although its response wavelength and intensity have been slightly changed, and provide a theoretical reference to improve the possible application of phenothiazine dye in DNA biosensor under ion irradiation.

Adsorption of ammonium ions onto the external surface of smectite: Effects of layer charge, concentration, anion and comparison with interlayer adsorption

The residual and release of ammonium in ion-adsorption rare earth tailings and soil are related to the interaction of NH4+ with clay minerals. Molecular dynamics simulations were used to study the adsorption and diffusion of NH4+ on the external surface of smectite. The factors, such as layer charge position (octahedral and tetrahedral substitution) and charge density (0.5, 1.0 and 1.5 e⋅uc−1, where uc denotes unit cell), initial NH4+ concentration (from 0.64 to 1.60 mol⋅L−1), and anion types (Cl−, NO3− and SO42−) were considered. The results of NH4+ adsorption on the external surface were also compared with that in the interlayer. The layer charge of smectite significantly affected the interaction between NH4+ and smectite. With increasing charge density, the major NH4+ surface complexes were changed from outer-sphere to inner-sphere, resulting in increased adsorption density and stability, which was verified by calculated hydration structure and adsorption free energies. The inner-sphere NH4+ complexes were located above the centers of the hexagonal rings and the Si tetrahedras for montmorillonite at a charge density of 1.0 e⋅uc−1, while only located in the vicinity of tetrahedral substitutions for beidellite. NO3− promoted the adsorption of NH4+ as inner-sphere complexes relative to Cl− and SO42−. As the water content in the interlayer increased, the confinement effect weakened and the mobility of NH4+ increased, and the NH4+ adsorption in the interlayer exhibited similar characteristics to that on the external surface at a water content of 10 H2O⋅uc−1.

Identifying the role of oxygen vacancy on cobalt-based perovskites towards peroxymonosulfate activation for efficient iohexol degradation

Oxygen vacancy (VO) is attracting extensive interest in heterogeneous peroxymonosulfate (PMS) activation, but its role remains elusive for water treatment. Herein, we constructed VO-tuned cobalt-based perovskite LaCoO3-VO, achieving superior activity (0.335 min−1) than LaCoO3 (0.124 min−1) for iohexol degradation. Nevertheless, VO did not directly serve as reactive sites, indicated by prohibited contaminant degradation via targeted poisoning of cobalt sites. Systemic electrochemical and spectroscopic measurements illustrate facile transformation of cobalt ions, increased charge density of depletion layer and low transfer resistance are attributed to VO manipulation. DFT calculations suggest reactant HSO5− is prone to attach defect site for elongated O-O bond. Experimental and theoretical results reveal the contributions of VO include adjusting PMS adsorption configuration, weakening lattice restraining of cobalt ions, reducing reaction barrier and optimizing electronic structures on perovskites. Our work attempts to understand energetic and kinetic factors of deficiency strategy for rational PMS-based degradation.

Micro-/Nanofibrillated Cellulose-Based Coating Formulations: A Solution for Improving Paper Printing Quality.

The use of micro-/nanofibrillated celluloses (M/NFCs) is often considered for the enhancement of paper properties, while it is still challenging to use them in lower weight gain coatings. This work explores how they might be used on the paper surface to improve the printing quality. In this regard, M/NFCs were produced using different pre-treatment methods, including mechanical (m-MFC), enzymatic (e-MFC), TEMPO-mediated oxidation (t-NFC) and cationization (c-NFC), and uniform coating formulations were developed through the cooking of starch and M/NFCs simultaneously. The formulations, at 6–8% of total solid concentration, were applied to the paper surface by roll coating, resulting in a dry coating weight of 1.5 to 3 g/m. Besides M/NFCs, other components such as starch betainate (a cationic starch ester; SB), Pluronics® (a triblock co-polymer), precipitated calcium carbonate (PCC) and betaine hydrochloride (BetHCl) were also used in the M/NFC-based coating formulations to observe their combined influence on the printing quality. The presence of M/NFCs improved the paper printing quality, which was further enhanced by the increase in cationic charge density due to the presence of BetHCl/SB, and also by Pluronics®. The cationic charge of c-NFC was also found to be effective for improving the gamut area and optical density of coated papers, whereas whiteness was often reduced due to the quenching of the brightening agent. BetHCl, on the other hand, improved the printing quality of the coated papers, even though it was more effective when combined with M/NFCs, PCC and Pluronics®, and also helped to retain paper whiteness.

Surfactants in electrokinetic remediation of sediments to enhance the removal of metals

PurposeThe study focuses on the use of surfactants as enhancing solutions in electrokinetic remediation trials on sediments, with the hypothesis that they will allow heavy metals to desorb from organic matter, and thus favour their removal to the solution.Materials and methodsA total of 15 remediation trials were conducted. As enhancing solutions, four different non-ionic commercial surfactants were used, either alone or in combination with citric acid (CA) or ethylenediaminetetraacetic acid (EDTA) in both compartments. A comparison with distilled water was also performed. 30–40 VDC was applied between activated titanium electrodes. The pH, electroosmotic flow (EOF), mineralogy of the samples (before and after the electrokinetic tests), and the percentage of removal of Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg were determined.Results and discussionEvery test showed an increase in current intensity during the first hours, and in certain cases, additional intensity peaks were found during the trial, which were mostly attributed to the establishment of EOF episodes. Depending on the case, EOF was transferred to the anolyte or the catholyte. Reversal of EOF occurred in one case, but was not detected in the others. Cr was primarily removed when CA was used. In the catholite, Ni, Cu, Zn, and Pb were extracted preferentially with EDTA. Surfactant B was more effective at removing Zn and As. Only a few treatments removed Cd with CA and surfactant C extracting the most. Hg was detected in the electrolytes of some experiments, being extracted with surfactant A in the catholyte in all cases, and with surfactant B and surfactant C with EDTA. Cr, Ni, Cu, Zn, Cd, and Pb were preferentially collected in the anolyte. Cu and Zn were found in trace levels in the catholyte.ConclusionsSurfactants have been shown to help with metal solubilisation to different degrees depending on the metal. Each metal has a unique optimal species combination in the enhancing electrolyte. The direction of the EOF is determined by the chemical conditions of the system as a whole, not by the type of surfactant. Surfactants in combination with CA and EDTA improve desorption in general, which has been attributed to an increase in charge density passed during the tests rather than a symbiotic enhancement between both types of enhancing solutions.

Surface Charge Characteristics of DC-GIL Insulator Under Multiphysics Coupled Field: Effects of Ambient Temperature, Load Current, and Gas Pressure

In this article, the surface charge characteristics of the direct current gas-insulated transmission lines (DC-GIL) insulator under thermal–electric coupled fields are investigated. A horizontally installed GIL with a basin-type insulator is employed. The 3-D charge distribution under different ambient temperatures, load currents, and gas pressures is obtained based on the finite-element method. It is found that the charge density increases with increasing ambient temperature since the bulk conduction is promoted due to the increasing insulator temperature. At lower ambient temperature, the surface charge distribution shows a more obvious difference in different radial directions along the insulator due to the increasing difference in electric conductivity in different directions. With increasing load current, the charge density increases, and the difference in charge density in different radial directions becomes more obvious. The charge density increases with increasing gas pressure although the temperature decreases, which is attributed to the domination of decreasing ion mobility over decreasing bulk conduction. It can be concluded that attention should be paid to these conditions when dealing with the insulation property of DC-GIL considering the effect of thermal gradient on the charge accumulation. Besides, simulation based on a 3-D model is necessary, especially for horizontal GILs.

Deep Utilization of Low-Grade Heat through Compositional Modulation of Multi-Component Liquid Desiccant

Low-grade heat is a challenge for deep utilization due to its low temperature. Based on the optimization of the saturated vapor pressure of liquid desiccant in absorption or dehumidification cooling systems, an idea of deep utilization of low-grade heat is proposed in this paper. Instead of optimizing the cycle process or equipment, this paper achieves this goal by obtaining a multi-component salt solution with the advantages of both strong moisture absorption capacity and lower regeneration temperature. The sensitivity of saturated vapor pressure to temperature is defined to evaluate the performance of the salt solution, and the sensitivity mechanism is revealed. The results show that the sensitivity of saturated vapor pressure to temperature increases with the increase of ion charge density, and compositional modulation is proposed to improve the sensitivity. The formula of a multi-component salt solution is taken as an example to illustrate the deep utilization of low-grade heat. As a result, the dehumidification performance of the multi-component dehumidification is equivalent to that of the typical desiccant solution, but its regeneration temperature is about 4 K lower. Furthermore, by using the concept proposed in this paper, it is pointed out that the utilization of low-grade heat can be improved by 40% approximately in an absorption cooling system.

Structure and Diffusion of Ionic PDMS Melts.

Ionic polymers exhibit mechanical properties that can be widely tuned upon selectively charging them. However, the correlated structural and dynamical properties underlying the microscopic mechanism remain largely unexplored. Here, we investigate, for the first time, the structure and diffusion of randomly and end-functionalized ionic poly(dimethylsiloxane) (PDMS) melts with negatively charged bromide counterions, by means of atomistic molecular dynamics using a united atom model. In particular, we find that the density of the ionic PDMS melts exceeds the one of their neutral counterpart and increases as the charge density increases. The counterions are condensed to the cationic part of end-functionalized cationic PDMS chains, especially for the higher molecular weights, leading to a slow diffusion inside the melt; the counterions are also correlated more strongly to each other for the end-functionalized PDMS. Temperature has a weak effect on the counterion structure and leads to an Arrhenius type of behavior for the counterion diffusion coefficient. In addition, the charge density of PDMS chains enhances the diffusion of counterions especially at higher temperatures, but hinders PDMS chain dynamics. Neutral PDMS chains are shown to exhibit faster dynamics (diffusion) than ionic PDMS chains. These findings contribute to the theoretical description of the correlations between structure and dynamical properties of ion-containing polymers.

An analytical approach to estimating electrostatic repulsion between soil particles

The electrostatic repulsion between soil particles has an important effect on the stability of soil aggregates and soil water movement. However, the electrostatic repulsive pressure is traditionally quantified through a complicated numerical method. In this study, the analytical expressions for calculating the midplane potential between soil particles in 1:1 and 2:1 electrolytes were derived respectively, consequently an analytical method for estimating the electrostatic repulsive pressure was obtained. The theoretical solutions of midplane potential between particles and electrostatic repulsive pressure are in good agreement with the numerical ones, and correctly predict the swelling pressure of montmorillonite. The surface potential, midplane potential and electrostatic repulsive pressure between soil particles calculated by the analytical method increase with increasing charge density, which depends on ionic polarization or/and polarization-induced covalent bond. For example, electrostatic repulsive pressure is the highest in non-polarized Li+, decreases in polarized Na+, and the lowest in K+ solution due to potassium’s relatively high polarization and polarization-induced covalent bond. The percentage of large soil pores (> 1 mm) and electrostatic repulsive pressure appear in a negative correlation, which is consistent with changes in the soil water infiltration rate, whereas the percentage of small soil pores (< 0.5 mm) has a positive relationship to electrostatic repulsive pressure. The ion polarization or/and polarization-induced covalent bond affect soil pore distribution and control soil water infiltration through significantly affecting the electrostatic repulsive pressure between soil particles. The analytical estimation of electrostatic repulsion is of great significance for understanding the physical/chemical processes in soils and quantifying the relations between mesoscopic processes and macroscopic phenomena.

Quaternary ammonium engineered polyamide membrane with high positive charge density for efficient Li+/Mg2+separation

The efficient separation of Li+/Mg2+ is the key to lithium extraction from salt lake brine. Herein, a multi-amino quaternary ammonium salt (3,5-dimethylhydrazide-benzyl trimethyl ammonium bromide, DHTAB) was designed and synthesized to modify pristine polyamide (PA) nanofiltration membranes. DHTAB was grafted on the surface of the PA nanofiltration membrane to construct a positively selective layer for Li+/Mg2+ separation. The introduction of DHTAB increased the membrane surface charge density to +5.16 mC m−2, which was nearly three times that of the pristine PA membrane. The increased charge density of the modified membrane led to a stronger Donnan exclusion for Mg2+, and accordingly a high MgCl2 rejection of 99.2%. The modified membranes exhibited a high Li+/Mg2+ separation factor of up to 60.1, when applied for MgCl2 and LiCl binary solution, which exceeded all known PA-based nanofiltration membranes.

Effect of Temperature on Grain Growth during Ti Electrodeposition in Lif–LiCl Eutectic Melt

1. IntroductionTi has superior properties, such as high specific strength, corrosion resistance, biocompatibility, and is used for many fields such as airplane, chemical plant, consumer products. However, its high manufacturing cost and poor processability have hindered its further spread. Thus, a number of smelting processes and processing methods have been investigated to reduce the cost and spread the use of Ti. Among them, plating Ti metal on inexpensive substrates is one of the methods that can utilize the surface properties of Ti. Electrodeposition is a promising plating method from the viewpoints of the cost and the flexibility in shape of substrate. Therefore, electrodeposition of Ti metal in high-temperature molten salts has been investigated for a long time [1–3].Our group has reported the electrodeposition of Ti films with compact and smooth surfaces in molten KF–KCl and LiF–LiCl containing Ti(III) ions at 923 K [4–7]. We also reported that the Ti films obtained in LiF–LiCl at 823 K had smoother surfaces [8]. In the present study, we investigated the effect of temperature on the grain growth and smoothness of Ti films electrodeposited in LiF–LiCl eutectic melt at 823–973 K.2. ExperimentalThe experiments were carried out in eutectic LiF–LiCl melt (30:70 mol%, melting point 774 K) at 823–973 K. The melt was placed in a nickel crucible and the experiments were conducted in an airtight Kanthal container in an argon glove box. As Ti(III) ion sources, Li2TiF6 (2.00 mol%) and Ti sponge (1.33 mol%) were added to the melt. The added amounts of Ti sponge were twice the amounts necessary to generate Ti(III) ions by comproportionation reaction between Ti(IV) ions and Ti(0) according to Eq. 1.Ti(0) + 3Ti(IV) → 4Ti(III) (1)Ni plates were used as working electrodes, and Ti rods was used as counter and reference electrodes. The samples prepared by galvanostatic electrolysis were analyzed by XRD and SEM/EDX after washing with distilled water to remove adhered salts.3. Results and DiscussionFig. 1 shows the optical and surface SEM images of the samples obtained by galvanostatic electrolysis at 823, 873, 923, and 973 K. The cathodic current density was 50 mA cm−2 and electrolysis time was 20 min. All the samples have a metallic luster and are confirmed to be Ti metal by XRD analysis. However, the brightness differs between samples, with the Ti film at 823 K showing the highest brightness. From the surface SEM images, the crystal grain size of Ti increases as the temperature rises. This tendency is reasonably explained by previous work on the temperature dependence on grain growth of Ti [9]. Also, the value of surface roughness (Sa) measured by SEM increases as the temperature increases. The smoothest Ti film with Sa = 2.05 ± 0.22 μm was obtained at 823 K. These results show that Ti film with smoother surface can be electrodeposited by suppressing the grain growth of Ti at lower temperatures.To obtain thicker films, electrolysis was conducted for longer time at 823 K, where grain growth is suppressed. Fig. 2 shows the optical and SEM images of the samples obtained by galvanostatic electrolysis at a cathodic current density of 50 mA cm−2 and charge densities of 60, 150, and 450 C cm−2. As shown in the SEM images, the thickness of the Ti film increases with the increase in charge density. Although some deposition onto the edge was observed at 450 C cm−2, the thickness of the Ti film reaches 100 μm.AcknowledgementA part of this work was supported by JSPS Fellows grant number 19J15015. A part of this study was conducted as a collaboration with Sumitomo Electric Industries, Ltd. The present address of Kouji Yasuda is Graduate School of Engineering, Kyoto Univ.

Electron-Irradiation-Induced Degradation of Transfer Characteristics in Super-Junction VDMOSFET

High electric-field stress is an effective solution to the recovery of irradiated devices. In this paper, the dependence of the recovery level on the magnitude of gate voltage and duration is investigated. Compared with the scheme of high gate-bias voltage with a short stress time, the transfer characteristics are significantly recovered by applying a low electric field with a long duration. When the electric field and stress time are up to a certain value, the threshold voltage almost approaches the limitation, which is less than that before irradiation. Meanwhile, the effect of temperature on the recovery of the irradiated devices is also demonstrated. The result indicates that a high temperature of 175 °C used for the irradiated devices’ annealing does not play a role in promoting the recovery of transfer characteristics. In addition, to obtain a deep-level understanding of threshold degradation, the first-principles calculations of three Si/SiO2 interfaces are performed. It is found that new electronic states can be clearly observed in the conduction bans and valence bands after the Si-H/-OH bonds are broken by electron irradiation. However, their distribution depends on the selection of the passivation scheme. Ultimately, it can be observed that the threshold voltage linearly decreases with the increase in interface charge density. These results can provide helpful guidance in the deep interpretation of threshold degradation and the recovery of the irradiated super-junction devices.

Green Crop Yam-Derived Carbons: Off-Plane Active Sites for Oxygen Electroreduction Identified by First-Principles.

Plant-derived nonprecious metal catalysts are considered one of the promising candidates of platinum for oxygen reduction reaction (ORR). In this work, the typical microscopic morphology of fresh green crop yam is first detected by cryoscanning electronic microscopy. Using the green and widely sourced yam with spherical starch in nature as a precursor, well-defined spherical carbons are prepared via hypersaline-assisted hydrothermal carbonization and NH3activation, featuring a high heteroatom doping level and a hierarchical porous structure. Experimental results and density functional theory (DFT) calculations reveal that diverse off-plane Fe-Nx-Cy ensembles on the spherical carbons trigger the high performance that exceeds state-of-art Pt/C and most reported carbon catalysts toward ORR in a KOH solution. The increased charge density and the bond length of Fe coordinated in the sites should be responsible for the significantly improved property. The easily editing of off-plane active sites from the simple carbon morphology may shed light on optimizing nonprecious carbons as next-generation catalysts for ORR.

Potential risk resulting from the influence of static magnetic field upon living organisms. Numerically simulated effects of the static magnetic field upon simple alkanols

Background: Recognising effects of static magnetic field (SMF) of varying flux density on flora and fauna is attempted. For this purpose, the influence of static magnetic field upon molecules of lower alkanols i.e. methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, S-butan-2-ol, isobutanol and tert-butanol is studied. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AFU (Arbitrary Field Unit; here 1AFU &amp;gt; 1000 T) flux density were performed in silico (computer vacuum), involving advanced computational methods. Results: SMF polarises molecules depending on applied flux density, but it neither ionises nor breaks valence bonds. Some irregularities in the changes of positive and negative charge densities and bond lengths provide evidence that molecules slightly change their initially fixed positions with respect to the force lines of the magnetic field. Length of some bonds and bond angles change with an increase in the applied flux density, providing, in some cases, polar interactions between atoms through space. Conclusions: Since SMF produced and increase in the negative charge density at the oxygen atom of the hydroxyl group and elongated the –O-H bond length, these results show that SMF facilitates metabolism of the alkanols.