Structure, spin reorientation and M?ssbauer effect studies of Tb0.3Dy0.7(Fe1?xAlx)1.95 alloys

The effect of Al substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb_0.3Dy_0.7(Fe_1−x Al_x)_1.95 alloys (x = 0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35) at room temperature and 77 K was investigated systematically. It was found that the primary phase of Tb_0.3Dy_0.7(Fe_1−x Al_x)_1.95 is the MgCu₂-type cubic Laves phase structure when x < 0.4 and the lattice constant a of Tb_0.3Dy_0.7(Fe_1−x Al_x)_1.95 increases approximately and monotonically with the increase of x. The substitution of Al leads to the fact that the magnetostriction λ inceases slightly in a low magnetic field (H ⩽ 40 kA/m), but decreases sharply and is easily close to saturation in a high applied field as x increases, showing that a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy. It was also found that the spontaneous magnetostriction λ ₁₁₁ decreases greatly with x increasing. The analysis of the M?ssbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the changes of composition and temperature, namely spin reorientation. A small amount of non-magnetic phase exists for x = 0.15 in Tb_0.3Dy_0.7(Fe_1−x Al_x)_1.95 alloys and the alloys become paramagnetic for x > 0.15 at room temperature, but at 77 K the alloys still remain magnetic phase even for x = 0.2. At room temperature and 77 K, the hyperfine field decreases and the isomer shifts increase with Al concentration increasing.     

Two-Dimensional Rossby Waves: Exact Solutions to Petviashvili Equation

The two-dimensional (2D) nonlinear Rossby waves described by the Petviashvili equation, which has been invoked as an ageostrophic extension of the barotropic quasi-geostrophic potential vorticity equation, can be investigated through the exact periodic-wave solutions for the Petviashvili equation, while the exact analytical periodic-wave solutions to the Petviashvili equation are obtained by using the Jacobi elliptic function expansion method. It is shown that periodic-wave 2D Rossby solutions can be obtained by this method, and in the limit cases, the 2D Rossby soliton solutions are also obtained.     

Temperature dependence of excitonic emission in cubic CdSe thin film

A detailed photoluminescence investigation of the thermal redshift and broadening of the excitonic line of cubic CdSe film grown by molecular beam epitaxy is presented. Free excitonic emission from the cubic CdSe film was observed at low temperature. Temperature-dependent measurement was performed to obtain material parameters related to exciton-phonon interaction by fitting the experimental data to the phenomenological model. The relative contribution of both acoustic and optical phonon to the band gap shrinkage and exciton linewidth broadening are discussed. Exciton binding energy of 16±1.5 meV was determined from the Arrhenius analysis.     

Crystal structure of Ni(II) complex and fluorescence properties of Zn(II) complex with the Schiff base derived from diethenetriamine and PMBP

The Schiff base, H₂L, was derived from 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and diethenetriamine. The crystal structure of [NiL(C₂H₅OH)]·H₂O obtained from ethanol solution was determined by X-ray diffraction analysis. The coordination geometry of Ni(II) ion is a distorted octahedron with three oxygen atoms and three nitrogen atoms. Under the excitation of ultraviolet light, strong fluorescence of solid Zn(II) complex was observed. In addition, the fluorescence enhancement was obtained in the presence of Zn²⁺ in THF solution of the ligand, indicating that H₂L may be a potential fluorescent sensor for Zn²⁺.     

Synthesis, characterization and mechanism of cetyltrimethylammonium bromide bilayer-encapsulated gold nanosheets and nanocrystals

Single-crystal Au nanosheets and fcc gold nanocrystals of uniform size were synthesized by a novel and simple route. The results of field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicated the formation of the single-crystal structure of gold nanosheets and fcc nanocrystals. Energy-dispersive analysis of X-ray (EDAX) showed absorbance of cetyltrimethylammonium bromide (CTAB) molecules onto the surface of gold nanostructures. Moreover, zeta potential measurements showed that CTAB-coated nanostructures were positively charged and the zeta potential remained almost the same upon centrifugation and redispersion of the resulting nanostructures in methanol, confirming the high stability of the surfactant-protected nanocomposites. Evolution of the nanostructures during the reaction was monitored by TEM observations. The results indicated that the formation of the gold nanostructures followed a two-step mechanism with a bilayer CTAB structure on the surface of the gold nanostructures.     

Intercalated kaolinite as an emerging platform for cancer therapy

An innovative cancer therapy strategy regarding the interface engineering of kaolinite has been designed. The exposed silanol group facilitates more guest species with high dispersion on the supports. Mn_3O_4 magnetic nanoparticles are uniformly distributed on external surfaces of the Kaolin_(C12N)with the Al–O–Mn bond for the detection of the tumor microenvironment by T1-MRI; Doxorubicin(DOX) are loaded in the interlayer space with the electrostatic interaction for chemo-treating; and KI is coated on the outer layer of the nanocomposites based on the electrostatic interaction for thyroid cancer targeting. The synergetic effects and the treatment mechanism enhanced by the interface engineering, KI@DOX-Mn_3O_4-Kaolin_(C12N)can cause remarkably low cell viability(57%, 200 μg/mL), tumor shrinking(75%, 20 μg/kg), and accumulation into the tumor tissues. The novel kaolinite based drug delivery system is expected to incorporate imaging diagnosis, targeted therapy and drug delivery into one single system for postoperative residual thyroid cancer treatment and observation for metastasis of focal area.     

LiB6Si: An indirect band gap semiconductor

Using first-principle calculations, mechanical properties, electronic structure, and Raman spectra of LiB₆Si structure were investigated. The band structures calculated by GGA-PBE and HSE06 methods reveal that LiB₆Si is an indirect band gap semiconductor. The band gap estimated by HSE06 method is about 2.24 eV, which is in good agreement with that of experimental value 2.27 eV. The calculated tensile stress-strain curves of LiB₆Si reveal that [010] direction is the cleavage direction under tensile strains. The calculated Raman spectra of LiB₆Si are also in good agreement with that of measured. The position of the band gap may provide a basis for further photocatalysis research on LiB₆Si.     

Stimuli-Responsive Fluorescent Nanoswitches: Solvent-Induced Emission Enhancement of Copper Nanoclusters

Copper nanoclusters (CuNCs) as a new class of fluorescent materials have attracted a great deal of interest due to their outstanding fluorescence properties. In this work, a variety of organic solvents were used to induce self-assembly of glutathione-capped CuNCs (GSH-CuNCs) to form ordered assemblies with enhanced fluorescence properties. Assemblies with multicolor fluorescence emission were constructed on the basis of the aggregation-induced emission (AIE) of GSH-CuNCs and the solvent effect. The fluorescence emission from these GSH-CuNCs assemblies can also be tuned from yellow to purple by changing the organic solvent. A possible mechanism based on the size of the assemblies and electron transfer was explored to explain the solvent effects on GSH-CuNCs. Stimuli-responsive nanoswitches with excellent reversibility can be controlled by changing the type of organic solvent and the ratio of the organic solvent to the aqueous solution of GSH-CuNCs. As the CuNCs assemblies exhibit strong, stable, and color-tunable fluorescence, they were employed as color-conversion materials for recognizing different organic solvents.     

Double-Shelled C@MoS2 Structures Preloaded with Sulfur: An Additive Reservoir for Stable Lithium Metal Anodes

The growth of Li dendrites hinders the practical application of lithium metal anodes (LMAs). In this work, a hollow nanostructure, based on hierarchical MoS₂ coated hollow carbon particles preloaded with sulfur (C@MoS₂/S), was designed to modify the LMA. The C@MoS₂ hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. More importantly, the encapsulated sulfur could gradually release lithium polysulfides during the Li plating/stripping, acting as an effective additive to promote the formation of a mosaic solid electrolyte interphase layer embedded with crystalline hybrid lithium-based components. These two factors together effectively suppress the growth of Li dendrites. The as-modified LMA shows a high Coulombic efficiency of 98 % over 500 cycles at the current density of 1 mA cm⁻². When matched with a LiFePO₄ cathode, the assembled full cell displays a highly improved cycle life of 300 cycles, implying the feasibility of the proposed LMA.