Influence Of Weak Magnetic Field Research Articles

Mechanistic insight of weak magnetic field trigger transformation of amorphous Fe(III)-(oxy)hydroxide for enhanced ferrate (VI) towards selective removal of natural organic matter.

It was important to regulate the formation of Fe-hydroxyl during ferrate (Fe(VI)) oxidation and hydrolysis which was beneficial for interfacial adsorption of natural organic matter (NOM). Based on the influence of weak magnetic field (WMF) on the physical and chemical characteristics of particles in chemistry. This study investigated the effect of WMF on Fe(VI) oxidation and Fe(III) flocculation performance by regulating iron species during hydrolysis, for NOM removal. Results indicated WMF efficiently accelerate the removal of NOM that the reactions rate constants in magnetization system was twice as much as the control group. With the structure and electrochemical analysis, WMF enhanced Hydrogen-bond and caused much polar hydroxyl groups combined with iron ions, further triggered Fe(III) transformed to amorphous Fe-hydroxide and ferrihydrite with large specific surface area and high surface activity which removed the pollutants by adsorption and co-precipitation, instead of crystalloid Fe2O3 and Fe3O4. In addition, the nucleation aggregation behavior and interaction energy of Fe-(oxy)hydroxide revealed that the lower free energy obtained in magnetization system, could lead to higher nucleation rate, and promoted the aggregation. WMF increased hydrophobicity of Fe-(oxy)hydroxides, further more easily adsorbed with humic acid (HA) and bovine serum albumin (BSA) with lower interaction energies than in control group. The selective removal mechanism of Fe-(oxy)hydroxide hardly to aggregate with pollutants which caused by the difference of electrostatic interaction, was illustrated that electronegativity HA and SA were liable to electrostatically attract with Fe-(oxy)hydroxide and removed while the low electronegativity BSA was difficult to remove which its attraction was weakened.

Influence of Weak Magnetic Field on Electrodeposition and Properties of Copper Films

Influence of Weak Magnetic Field on Electrodeposition and Properties of Copper Films

Superconducting heterostructure with barrier with strong spin-orbit interaction

We report on observation of superconducting current and AC Josephson effect in mesa-heterostructures with spin-singlet superconducting electrodes, interlayered by a barrier material with strong spin-orbit interaction. The mesa-heterostructures were Nb/Au/Sr2IrO4/YBa2Cu3Ox with d=5 nm and 7 nm thick interlayer of strontium iridate Sr2IrO4, which is known as a canted antiferromagnetic insulator with a weak magnetic moment from Ir atoms and with spin-orbit interaction energy ESO ~0.4 eV. The superconducting critical current density was jC ≈0.3 A/cm2 at T=4.2 K for mesa-heterostructures with d=7 nm and a few times higher for d=5 nm. The zero-bias conductance peak has been observed due to low energy states originated at Sr2IrO4/YBa2Cu3Ox interface. Under influence of weak magnetic field the critical current IC (H) dependences showed Fraunhofer-like pattern indicating absence of pinholes, supported also by oscillating with microwave power Shapiro steps. Fiske resonance steps with voltage positions deviated from the ordinary ones were registered for mesas with d=5 nm.

Superconducting Current in Mesa Structures with Interlayer of Strontium Iridate, a Material Having Strong Spin-Orbit Interaction

We report on observation of superconducting current and AC Josephson effect in mesa-heterostructures with the interfaces comprised spin-singlet superconducting electrodes, coupled by a barrier made from strontium iridate, a material with the strong spin-orbit interaction. The superconducting critical current density was jC ≈ 0.3 A/cm2 at T = 4.2 K for mesa-heterostructures with d = 7 nm and jC ≈ 4 A/cm2 for d = 5 nm. The zero-bias conductance peak has been observed due to low energy states originated at Sr2IrO4/YBa2Cu3Ox interface. Under influence of weak magnetic field the critical current IC(H) dependences showed Fraunhofer-like pattern indicating absence of pinholes, supported also by oscillating with microwave power Shapiro steps. Fiske resonance steps with voltage positions deviated from the ordinary ones were registered for mesas with d = 5 nm.

Рекомбинация носителей заряда через возбужденные уровни бора в кремнии при низких температурах

In present article was studied the process of recombination of charged carriers across shallow impurity boron’s centers in silicon at low temperatures. Major attention was devoted to theoretical interpretation of empiric temperature dependencies of lifetime τ(T) of the carriers in the temperature range of (1.7 – 4.2) K under doped impurity concentrations nB ≥ 1014 sm – 3 with compensation ≤ 10% (nD + nA ≤ 1013 sm – 3). It is enough exactly determined that shallow excited level with binding energy 5 meV (3s-state) is almost resonant. The approximate formulas for the coefficient of resonant capture are obtained. Influence of weak magnetic field (10 – 100) Gs on value of the coefficient of resonant capture is analyzed, as for showed that weak magnetic field (in order 10 Gs) loosely decreases of carrier’s lifetime in such a way to stimulate a process of their recombination.

Enhanced chromium(VI) removal by zero-valent iron in the presence of anions and a weak magnetic field: Batch and column tests

In this study, batch and column tests were conducted to evaluate the influence of selected anions (ClO4−, NO3−, Cl− and SO42−) on Cr(VI) removal by zero-valent iron (ZVI) with and without a weak magnetic field (WMF). Batch kinetic experiments demonstrated a synergetic enhancing effect of WMF and each anion on Cr(VI) removal. In addition, the ratio of the Cr(VI) removal rate constant for each tested anion to that of deionized water (i.e., the promotion factor of the combined effect) exhibited a hyperbolic increase as a function of anion concentration. Based on the magnitudes of their enhancing effects, the anions were ranked from most to least enhancing: SO42− > Cl− > ClO4− > NO3−. The synergetic effect of WMF and anions was also obvious in a continuous flow system, which could both dramatically extend the lifespan of ZVI systems and improve the efficiency of Cr(VI) removal. The influence of WMF and the tested anions on ZVI corrosion products was investigated by scanning electron microscopy and X-ray diffraction. These findings could encourage the application of ZVI/WMF technology in the field.

Influence of weak magnetic field and tartrate on the oxidation and sequestration of Sb(III) by zerovalent iron: Batch and semi-continuous flow study

The influence of weak magnetic field (WMF) and tartrate on the oxidation and sequestration of Sb(III) by zerovalent iron (ZVI) was investigated with batch and semi-continuous reactors. The species analysis of antinomy in aqueous solution and solid precipitates implied that both Sb(III) adsorption preceding its conversion to Sb(V) in solid phase and Sb(III) oxidation to Sb(V) preceding its adsorption in aqueous phase occurred in the process of Sb(III) sequestration by ZVI. The application of WMF greatly increased the rate constants of Sbtot (total Sb) and Sb(III) disappearance during Sb(III)-tartrate and uncomplexed-Sb(III) sequestration by ZVI. The enhancing effect of WMF was primarily due to the accelerated ZVI corrosion in the presence of WMF, as evidenced by the influence of WMF on the change of solution and solid properties with reaction. However, tartrate greatly retarded Sb removal by ZVI. It was because tartrate inhibited ZVI corrosion, competed with Sb(III) and Sb(V) for the active surface sites, increased the negative surface charge of the generated iron (hydr)oxides due to its adsorption, and formed soluble complexes with Fe(III). The positive effect of WMF on Sb(III)-tartrate and uncomplexed-Sb(III) removal by ZVI was also verified with a magnetic semi-continuous reactor.

Weak magnetic field significantly enhances selenite removal kinetics by zero valent iron

The effect of weak magnetic field (WMF) on Se(IV) removal by zero valent iron (ZVI) was investigated as functions of pH and initial Se(IV) concentrations. The presence of WMF significantly accelerated Se(IV) removal and extended the working pH range of ZVI from 4.0–6.0 to 4.0–7.2. The WMF induced greater enhancement in Se(IV) removal by ZVI at lower initial Se(IV) concentrations. The influence of WMF on Se(IV) removal by ZVI was associated with a more dramatic drop in ORP and a more rapid release of Fe2+ compared to the case without WMF. SEM and XRD analysis revealed that WMF accelerated the corrosion of ZVI and the transformation of amorphous iron (hdyr)oxides to lepidocrocite. XANES analyses showed that WMF expedited the reduction of Se(IV) to Se(0) by ZVI at pH 6.0 when its initial concentration was ≤20.0 mg L−1. Se(IV) dosed at 40.0 mg L−1 was removed by ZVI via adsorption followed by reduction to Se(0) at pH 7.0 but via adsorption at 7.2 in the presence of WMF. Regardless of WMF, Se(IV) applied at 40.0 mg L−1 was removed by reduction at pH 4.0–6.0. The WMF-induced improvement in Se(IV) removal by ZVI may be mainly attributable to the Lorentz force and magnetic field gradient force. Employing WMF to enhance Se(IV) removal by ZVI is a promising and environmental-friendly method since it does not need extra energy and costly reagents.

Cultivation and characteristics of micro-aerobic activated sludge with weak magnetic field

Dynamic experiments were carried out in two reactors with anaerobic sludge as the seed sludge under low dissolved oxygen concentration (lower than 1.0 mg/L) condition, one reactor with magnetic particle and the dosage being 4 g/L determined by the static experiments and the other as the blank control. The synthetic glucose solution was used to culture the micro-aerobic sludge. The results indicated that the reactor with magnetic particles had a higher chemical oxygen demand removal efficiency and mixed liquid suspended sludge than the blank in which no magnetic particles existed. The sludge under the influence of weak magnetic field had better settling property with the average value of sludge volumetric index (SVI) lower than 100 mL/g, while in the reactor without magnetic particles, the sludge had a loose structure, poor setting property, and a SVI value higher than 200 mL/g. The influence of the weak magnetic field on the flocculation capability of the sludge was investigated through the testing of the indexes such as the total dose of extracellular polymers, the ratio of protein and polysaccharides, flocculating ability, relative hydrophobicity, and surface charge. The results showed that the existence of magnetic particles had greatly increased flocculating performance of the sludge.

Transformations of microdefect structure in silicon crystals under the influence of weak magnetic field

Quantitative characterization of complex microdefect structures in annealed silicon crystals (1150 °С, 40 h) and their transformations after exposing for one day in a weak magnetic field (1 T) has been performed by analyzing the rocking curves, which have been measured by a high-resolution double-crystal X-ray diffractometer. Based on the characterization results, which have been obtained by using the formulas of the dynamical theory of X-ray diffraction by imperfect crystals with randomly distributed microdefects of several types, the concentrations and average sizes of oxygen precipitates and dislocation loops after imposing the magnetic field and their dependences on time after its removing have been determined.

Changes in the state of paramagnetic centers and lattice parameter of micro-structured Si under the influence of weak magnetic field

Changes in the state of paramagnetic centers and lattice parameter of micro-structured Si under the influence of weak magnetic field

Influence of weak magnetic field on growth morphology of Zn branched electrodeposits

The influence of a weak magnetic field on the microstructure of the Zn electrode posits prepared in a thin concentric electrode cell is investigated. Mechanism o f the effect of the magnetohydrodynamic (MHD) flow on the morphological transiti on is proposed through experimental evidences. 1) In the early growth phase of a crystallite, the unbalanced force caused by the MHD flow on the crystallite, wh ich suspends in the electrolyte close to the previous branch, rotates its prefer ential growth orientation towards the downstream of the MHD flow; 2) A stable co ncentration profile is formed in the vicinity of the electrodeposits by the MHD flow. After the crystallite grows large enough to stick on its previous branch, and the concentration of the electrolyte is high enough for both the primary bra nch and its secondary branches, the single-crystalline dendrites will grow strai ght. But if the concentration of the electrolyte is small, the secondary branche s crowd to the side facing the upstream of the MHD flow and the primary branch i s forced to bend towards the downstream of the MHD flow. A spiral structure in t he branched electrodeposits grown in a magnetic field is formed by this mechanis m.

Change of mechanical properties of Fe-Cr-Ni steel after corrosion of steel in chlorine medium without and with magnetic field

The influence of weak magnetic field (B = 0.05 T) on mechanical properties, i.e. the torsional and twisting strength, of Fe-Cr-Ni steel (18.2% Cr, 9.4% Ni, 0.08% Mn, 0.6% Ti, 0.04% Co) has been investigated. When a permanent magnetic field is used, the steel wire, treated in acidic chloride solutions (11% FeCl3·6H2O or 11% FeCl3·6H2O + 3% NaCl), loses its mechanical properties more rapidly than if the magnetic field is not used. It suggests that the loss of mechanical properties of the wire is connected with peculiarities of formation of pitting. When pitting is formed without magnetic field, it penetrates preferably in depth of steel, meanwhile in the magnetic field pitting is formed preferably on the surface area.