Magnetorheological Effect of Magnetoactive Elastomer with a Permalloy Filler.

Within the frames of this study, the synthesis of a permalloy to be used as a filler for magnetoactive and magnetorheological elastomers (MAEs and MREs) was carried out. By means of the mechanochemical method, an alloy with the composition 75 wt.% of Fe and 25 wt.

Bethe-Salpeter Equation at the Critical End Point of the Mott Transition.

Strong repulsive interactions between electrons can lead to a Mott metal-insulator transition. The dynamical mean-field theory (DMFT) explains the critical end point and the hysteresis region usually in terms of single-particle concepts, such as the spectral function and the quasiparticle weight. In this Letter, we reconsider the critical end point of the metal-insulator transition on the DMFT's two-particle level.

Mechanistic pathways of cationic and anionic surfactants sorption by kaolinite in water.

Surfactants are widely used in many chemical industries and as primary components of cleaning detergents due to their specific characteristics, which in turn results in high pollution of domestic and industrial wastewaters by such substances. In this study, the mechanistic pathways of the adsorption of cationic benzyl-dimethyl-dodecyl ammonium bromide (BDDAB) and anionic sodium dodecyl sulfate (SDS) surfactants on kaolinite clay in water were investigated. The results showed that the adsorption of anionic surfactant (SDS) on kaolinite is better compared with cationic surfactant (BDDAB), wherein the ♦maximum adsorption capacity was found 161.

Chain Formation and Phase Separation in Ferrofluids: The Influence on Viscous Properties.

Ferrofluids have attracted considerable interest from researchers and engineers due to their rich set of unique physical properties that are valuable for many industrial and biomedical applications. Many phenomena and features of ferrofluids' behavior are determined by internal structural transformations in the ensembles of particles, which occur due to the magnetic interaction between the particles. An applied magnetic field induces formations, such as linear chains and bulk columns, that become elongated along the field.

Efficient and Stable MAPbI-Based Perovskite Solar Cells Using Polyvinylcarbazole Passivation.

Hybrid perovskite solar cells attract a great deal of attention due to the feasibility of their low-cost production and their demonstration of impressive power conversion efficiencies (PCEs) exceeding 25%. However, the insufficient intrinsic stability of lead halides under light soaking and thermal stress impedes practical implementation of this technology. Herein, we show that the photothermal aging of a widely used perovskite light absorber such as MAPbI can be suppressed significantly by using polyvinylcarbazole (PVC) as a stabilizing agent.

Electronic correlations in uranium hydride UHunder pressure.

We report results of calculations based on density functional theory and dynamical mean-field theory for the electronic structure of uranium hydride UHunder pressure, a compound of the uranium-based hydride family some members of which have been predicted to be superconducting. The effective electronic mass enhancement*/∼ 1.4 indicates that the Coulomb correlations have a moderate strength.

Field-induced circulation flow in magnetic fluids.

In this paper, we present results of a theoretical study of circulation flow in ferrofluids under the action of an alternating inhomogeneous magnetic field. The results show that the field with the amplitude of about 17 kA m and angular frequency 10 s can induce mesoscopic flow with a velocity amplitude of about 0.5 mm s.

Role of particle clusters on the rheology of magneto-polymer fluids and gels.

Even in the absence of cross-linking, at large enough concentration, long polymer strands have a strong influence on the rheology of aqueous systems. In this work, we show that solutions of medium molecular weight (120 000-190 000 g mol) alginate polymer retained a liquid-like behaviour even for concentrations as large as 20% w/v. On the contrary, solutions of alginate polymer of larger (and also polydisperse) molecular weight (up to 600 000 g mol) presented a gel-like behaviour already at concentrations of 7% w/v.

On the theory of magnetic hyperthermia: clusterization of nanoparticles.

Experiments show that clusters consisting of nano-sized ferromagnetic particles strongly affect the intensity of heat production during magnetic hyperthermia. In this paper, a theoretical study and mathematical modelling of the heat production by clusters of single-domain ferromagnetic particles, immobilized in a host medium, are presented. Two situations of strong and weak magnetic anisotropy of the particles are considered.

Unraveling the Impact of Hole Transport Materials on Photostability of Perovskite Films and p-i-n Solar Cells.

We investigated the impact of a series of hole transport layer (HTL) materials such as Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), NiO, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), and polytriarylamine (PTA) on photostability of thin films and solar cells based on MAPbI, CsFAPbI, CsMAFAPbI, CsMAFAPb(BrI), and CsFAPb(BrI) complex lead halides. Mixed halide perovskites showed reduced photostability in comparison with similar iodide-only compositions. In particular, we observed light-induced recrystallization of all perovskite films except MAPbI with the strongest effects revealed for Br-containing systems.

Unravelling the Material Composition Effects on the Gamma Ray Stability of Lead Halide Perovskite Solar Cells: MAPbI Breaks the Records.

In this work, we report a comparative study of the gamma ray stability of perovskite solar cells based on a series of perovskite absorbers including MAPbI (MA = methylammonium), MAPbBr, CsFAPbI (FA = formamidinim), CsMAFAPbI, CsPbI, and CsPbBr We reveal that the composition of the perovskite material strongly affects the radiation stability of the solar cells. In particular, solar cells based on the MAPbI were found to be the most resistant to gamma rays since this perovskite undergoes rapid self-healing due to the special gas-phase chemistry analyzed with calculations. The fact that the solar cells based on MAPbI can withstand a 1000 kRad gamma ray dose without any noticeable degradation of the photovoltaic properties is particularly exciting and shifts the paradigm of research in this field toward designing more dynamic rather than intrinsically robust (e.

L-Lysine-modified FeO nanoparticles for magnetic cell labeling.

The efficiency of magnetic labeling with L-Lys-modified FeO magnetic nanoparticles (MNPs) and the stability of magnetization of rat adipose-derived mesenchymal stem cells, lineage-negative (Lin(-)) hematopoietic progenitor cells from mouse bone marrow and human leukemia K562 cells were studied. For this purpose, covalent modification of MNPs with 3-aminopropylsilane and N-di-Fmoc-L-lysine followed by removal of N-protecting groups was carried out. Since the degree of hydroxylation of the surface of the starting nanoparticles plays a crucial role in the silanization reaction and the possibility of obtaining stable colloidal solutions.

Surface-Dependent Osteoblasts Response to TiO Nanotubes of Different Crystallinity.

One of the major challenges of implantology is to design nanoscale modifications of titanium implant surfaces inducing osseointegration. The aim of this study was to investigate the behavior of rat osteoblasts cultured on anodized TiO nanotubes of different crystallinity (amorphous and anatase phase) up to 24 days. TiO nanotubes were fabricated on VT1-0 titanium foil via a two-step anodization at 20 V using NHF as an electrolyte.

Characterization of the defect structure of oxide nanoparticles with the use of deuterium probes.

The method of using deuterium probes was proposed for studying the defect structure of oxide nanoparticles. It was based on the fact that in the course of annealing nanoparticles in deuterium, clusters consisting of point defects and deuterium atoms are formed. The content of the clusters depended on the type of defects.

Light or Heat: What Is Killing Lead Halide Perovskites under Solar Cell Operation Conditions?

We report the first systematic assessment of intrinsic photothermal stability of a large panel of complex lead halides APbX incorporating different univalent cations (A = CHNH, [NHCHNH], Cs) and halogen anions (X = Br, I) using a series of analytical techniques such as UV-vis and X-ray photoelectron spectroscopy, X-ray diffraction, EDX analysis, atomic force and scanning electron microscopy, ESR spectroscopy, and mass spectrometry. We show that heat stress and light soaking induce a severe degradation of perovskite films even in the absence of oxygen and moisture. The stability of complex lead halides increases in the order MAPbBr < MAPbI < FAPbI < FAPbBr < CsPbI < CsPbBr, thus featuring all-inorganic perovskites as the most promising absorbers for stable perovskite solar cells.

Thermal Effects and Halide Mixing of Hybrid Perovskites: MD and XPS Studies.

Thermal effects in organo-metal halide perovskites are studied by ab initio molecular dynamics (MD) simulations performed at effective temperatures of 293 and 383 K and by X-ray photoelectron spectroscopy (XPS). We find that the cause of thermal instability in this class of perovskites is the rotation of the methylammonium (MA) groups that destroy the rigid lattice of pure compounds (MAPbI and MAPbBr). When the Pb-I lattice is initially distorted by partial replacement of the I with Cl or Br, this not only prevents formation of PbI seeds but also improves lattice flexibility and stability against the temperature-induced motion and rotation of MA groups.

Scaling theory of magnetism in frustrated Kondo lattices.

A scaling theory of the Kondo lattices with frustrated exchange interactions is developed, criterium of antiferromagnetic ordering and quantum-disordered state being investigated. The calculations taking into account magnon and incoherent spin dynamics are performed. Depending on the bare model parameters, one or two quantum phase transitions into non-magnetic spin-liquid and Kondo Fermi-liquid ground states can occur with increasing the bare coupling constant.

DC Self-Field Critical Current in Superconductor Dirac-Cone Material/Superconductor Junctions.

Recently, several research groups have reported on anomalous enhancement of the self-field critical currents, (sf,), at low temperatures in superconductor/Dirac-cone material/superconductor (S/DCM/S) junctions. Some papers attributed the enhancement to the low-energy Andreev bound states arising from winding of the electronic wave function around DCM. In this paper, (sf,) in S/DCM/S junctions have been analyzed by two approaches: modified Ambegaokar-Baratoff and ballistic Titov-Beenakker models.

p-wave superconductivity in iron-based superconductors.

The possibility of p-wave pairing in superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor.

Magnetic Nanoclusters Coated with Albumin, Casein, and Gelatin: Size Tuning, Relaxivity, Stability, Protein Corona, and Application in Nuclear Magnetic Resonance Immunoassay.

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated iron nanoparticles with four proteins: bovine serum albumin, casein, and gelatins A and B, and we conducted a comprehensive comparative study of their properties essential to applications in biosensing.

Ferrogels Ultrasonography for Biomedical Applications.

Ferrogels (FG) are magnetic composites that are widely used in the area of biomedical engineering and biosensing. In this work, ferrogels with different concentrations of magnetic nanoparticles (MNPs) were synthesized by the radical polymerization of acrylamide in stabilized aqueous ferrofluid. FG samples were prepared in various shapes that are suitable for different characterization techniques.

High-Energy and High-Power-Density Potassium Ion Batteries Using Dihydrophenazine-Based Polymer as Active Cathode Material.

Polymeric aromatic amines were shown to be very promising cathodes for lithium-ion batteries. Surprisingly, these materials are scarcely used for designing post-lithium batteries. In this Letter, we investigate the application of the high-voltage poly(-phenyl-5,10-dihydrophenazine) (p-DPPZ) cathodes for K-ion batteries.

Quantum Diffusion of Deuterium in Sodium.

The online nuclear reaction analysis technique has been applied to study the temperature dependence of deuterium diffusion coefficients for deuterium in sodium at temperatures ranging between 110 and 240 K, and at cryogenic temperatures, below 160 K, tunneling of deuterium atoms in the metal lattice has been observed. Above 160 K, diffusion occurs by the classical mechanism of overbarrier atomic jumps. Results of quantum diffusion of deuterium in a metal have been obtained for the first time; they used to be known only for the lightest hydrogen isotope, protium, in niobium and tantalum.

Magnetic hyperthermia in a system of immobilized magnetically interacting particles.

This paper deals with the theoretical study of magnetic hyperthermia, induced by a system of immobilized single-domain ferro- (ferri-) magnetic particles under the action of an oscillating magnetic field. It is supposed that the particles are randomly distributed in a host medium. The effect of magnetic interparticle interaction on the intensity of the heat production is the focus of our attention.

Preparation, Crystal Chemistry, and Hidden Magnetic Order in the Family of Trigonal Layered Tellurates AMn(4+)TeO (A = Li, Na, Ag, or Tl).

We report the first four magnetic representatives of the trigonal layered AM(4+)TeO (here, M = Mn) family. NaMnTeO was synthesized from NaMnO, NaNO, and TeO at 650-720 °C, but analogues for which A = Li and K could not be obtained by direct synthesis. However, those for which A = Li, Ag, and Tl (but not K) were prepared by exchange reactions between NaMnTeO and the corresponding molten nitrates.