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<jats:p>The doping effects of transition metals (TMs = Mn, Co, Ni, and Cu) on the superconducting critical parameters are investigated in the films of iron selenide (Li,Fe)OHFeSe. The samples are grown via a matrix-assisted hydrothermal epitaxy method. Among the TMs, the elements of Mn and Co adjacent to Fe are observed to be incorporated into the crystal lattice more easily. It is suggested that the doped TMs mainly occupy the iron sites of the intercalated (Li,Fe)OH layers rather than those of the superconducting FeSe layers. We find that the critical current density <jats:italic>J</jats:italic> <jats:sub>c</jats:sub> can be enhanced much more strongly by the Mn dopant than the other TMs, while the critical temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> is weakly affected by the TM doping.</jats:p>

<jats:p>The magnetic cooling utilizing magneto-caloric effect is recognized as promising energy efficiency and environmentally friendly technology. Here we report a systematical study on the microstructures, magnetic properties and cryogenic magneto-caloric performances of the Gd<jats:sub>20</jats:sub>Ho<jats:sub>20</jats:sub>Tm<jats:sub>20</jats:sub>Cu<jats:sub>20</jats:sub>Ni<jats:sub>20</jats:sub> amorphous ribbons. It is found that the ribbons reveal a second-order phase transition and are accompanied by a table-shaped magneto-caloric effect. The calculated magnetic-entropy-change maximum |Δ<jats:italic>S</jats:italic> <jats:sub>M</jats:sub>|, temperature averaged entropy change (i.e., TEC(10)), and refrigerant capacity reach 13.9 J/kg⋅K, 13.84 J/kg⋅K and 740 J/kg with magnetic field change of 0–7 T, respectively, indicating that the present Gd<jats:sub>20</jats:sub>Ho<jats:sub>20</jats:sub>Tm<jats:sub>20</jats:sub>Cu<jats:sub>20</jats:sub>Ni<jats:sub>20</jats:sub> amorphous ribbons are good candidates for magnetic cooling.</jats:p>

<jats:p>The side effects of chemotherapy are mainly the poor control of drug release. Magnetic nanoparticles (MNPs) have super-paramagnetic behaviors which are preferred for biomedical applications such as in targeted drug delivery, besides, in magnetic recording, catalysis, and others. MNPs, due to high magnetization response, can be manipulated by the external magnetic fields to penetrate directly into the tumor, thus they can act as ideal drug carriers. MNPs also play a crucial role in drug delivery system because of their high surface-to-volume ratio and porosity. The drug delivery in tumor therapy is related to the sizes, shapes, and surface coatings of MNPs as carriers. Therefore, in this review, we first summarize the effects of the sizes, shapes, and surface coatings of MNPs on drug delivery, then discuss three types of drug release systems, <jats:italic>i.e.</jats:italic>, pH-controlled, temperature-controlled, and magnetic-controlled drug release systems, and finally compare the principle of passive drug release with that of active drug release in tumor therapy.</jats:p>

<jats:p>Tumor-targeted magnetic hyperthermia has recently attracted much attention. Magnetic nanoparticles (NPs) are heat mediator nanoprobes in magnetic hyperthermia for cancer treatment. In this paper, single cubic spinel structural Zn<jats:sub>0.3</jats:sub>Fe<jats:sub>2.7</jats:sub>O<jats:sub>4</jats:sub> magnetic NPs with sizes of 14 nm–20 nm were synthesized, followed by coating with SiO<jats:sub>2</jats:sub> shell. The SLP value of Zn<jats:sub>0.3</jats:sub>Fe<jats:sub>2.7</jats:sub>O<jats:sub>4</jats:sub>/SiO<jats:sub>2</jats:sub> NPs below 20 nm changes non-monotonically with the concentration of solution under the alternating current (AC) magnetic field of 430 kHz and 27 kA/m. SLP values of all Zn<jats:sub>0.3</jats:sub>Fe<jats:sub>2.7</jats:sub>O<jats:sub>4</jats:sub>/SiO<jats:sub>2</jats:sub> NPs appear a peak value with change of solution concentration. The solution concentrations with optimal SLP value decrease with increasing magnetic core size. This work can give guidance to the better prediction and control of the magnetic hyperthermia performance of materials in clinical applications.</jats:p>

<jats:p>We theoretically investigate the exact soliton solutions of anisotropic ferromagnetic wires with Dzyaloshinskii–Moriya interaction. For example, we give the bright and black soliton solutions. From these results we find that the Dzyaloshinskii–Moriya interaction affects the existence region of soliton, spin-wave transport, and soliton dynamic properties. As the Dzyaloshinskii–Moriya interaction grows, the soliton width is widened, which provides a way to control the soliton dynamics.</jats:p>

<jats:p>The growth of <jats:italic>γ</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> thin films on mica by molecular beam epitaxy is studied. Single-crystalline <jats:italic>γ</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> is achieved at a relatively low growth temperature. An ultrathin <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystalline <jats:italic>γ</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved <jats:italic>γ</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> thin films.</jats:p>

<jats:p>Na<jats:sub>5</jats:sub>Y<jats:sub>9</jats:sub>F<jats:sub>32</jats:sub> single crystals doped with ∼ 0.8-mol% Ho<jats:sup>3+</jats:sup>, ∼ 1-mol% Tm<jats:sup>3+</jats:sup>, and various Er<jats:sup>3+</jats:sup> ion concentrations were prepared by a modified Bridgman method. The effects of Er<jats:sup>3+</jats:sup> ion concentration on 2.0-μm emission excited by an 800-nm laser diode were investigated with the help of their spectroscopic properties. The intensity of 2.0-μm emission reached to maximum when the Er<jats:sup>3+</jats:sup> ion concentration was ∼ 1 mol%. The energy transfer mechanisms between Er<jats:sup>3+</jats:sup>, Ho<jats:sup>3+</jats:sup>, and Tm<jats:sup>3+</jats:sup> ions were identified from the change of the absorption spectra, the emission spectra, and the measured decay curves. The maximum 2.0-μm emission cross section of the Er<jats:sup>3+</jats:sup>/Ho<jats:sup>3+</jats:sup>/Tm<jats:sup>3+</jats:sup> tri-doped Na<jats:sub>5</jats:sub>Y<jats:sub>9</jats:sub>F<jats:sub>32</jats:sub> single crystal reached 5.26 × 10<jats:sup>−21</jats:sup> cm<jats:sup>2</jats:sup>. The gain cross section spectra were calculated according to the absorption and emission cross section spectra. The cross section for ∼ 2.0-μm emission became a positive gain once the inversion level of population was reached 30%. The energy transfer efficiency was further increased by 11.81% through the incorporation of Er<jats:sup>3+</jats:sup> ion into Ho<jats:sup>3+</jats:sup>/Tm<jats:sup>3+</jats:sup> system estimated from the measured lifetimes of Ho<jats:sup>3+</jats:sup>/Tm<jats:sup>3+</jats:sup>- and Er<jats:sup>3+</jats:sup>/Ho<jats:sup>3+</jats:sup>/Tm<jats:sup>3+</jats:sup>-doped Na<jats:sub>5</jats:sub>Y<jats:sub>9</jats:sub>F<jats:sub>32</jats:sub> single crystals. The present results illustrated that the Er<jats:sup>3+</jats:sup>/Ho<jats:sup>3+</jats:sup>/Tm<jats:sup>3+</jats:sup> tri-doped Na<jats:sub>5</jats:sub>Y<jats:sub>9</jats:sub>F<jats:sub>32</jats:sub> single crystals can be used as promising candidate for 2.0-μm laser.</jats:p>

<jats:p>Aiming to achieve InAs quantum dots (QDs) with a long carrier lifetime, the effects of Sb component in cap layers on the band alignment of the InAs/GaAsSb QDs have been studied. InAs QDs with high density and uniformity have been grown by molecular beam epitaxy. With increasing Sb composition, the InAs/GaAsSb QDs exhibit a significant red-shift and broadening photoluminescence (PL). With a high Sb component of 22%, the longest wavelength emission of the InAs/GaAs<jats:sub>0.78</jats:sub>Sb<jats:sub>0.22</jats:sub> QDs occurs at 1.5 μm at room temperature. The power-dependence PL measurements indicate that with a low Sb component of 14%, the InAs/GaAs<jats:sub>0.86</jats:sub>Sb<jats:sub>0.14</jats:sub> QDs have a type-I and a type-II carrier recombination processes, respectively. With a high Sb component of 22%, the InAs/GaAs<jats:sub>0.78</jats:sub>Sb<jats:sub>0.22</jats:sub> QDs have a pure type-II band alignment, with three type-II carrier recombination processes. Extracted from time-resolved PL decay traces, the carrier lifetime of the InAs/GaAs<jats:sub>0.78</jats:sub>Sb<jats:sub>0.22</jats:sub> QDs reaches 16.86 ns, which is much longer than that of the InAs/GaAs<jats:sub>0.86</jats:sub>Sb<jats:sub>0.14</jats:sub> QDs (2.07 ns). These results obtained here are meaningful to realize high conversion efficiency intermediate-band QD solar cells and other opto-electronic device.</jats:p>

<jats:p>To investigate the optical properties of the ternary nanostructures, the nanodisk, core–shell, and three-sphere structures are constructed. The extinction coefficients and electric near-field distributions of these structures are calculated by the discrete dipole approximation (DDA) method. The result shows that the nanodisk structure has the best extinction efficiency in the three structures. Furthermore, several three-material combinations of the nanodisk structures are investigated. The ternary nanodisk structure composed of TiO<jats:sub>2</jats:sub> and two noble metals (Au, Ag or Pt) has higher extinction coefficient and near-field intensity than the nanodisk consisting of Au, TiO<jats:sub>2</jats:sub> and a semiconductor (PbSe, Ge, MoS<jats:sub>2</jats:sub>, CdSe, CdS or TiO<jats:sub>2</jats:sub>). Especially, TiO<jats:sub>2</jats:sub>/Ag/Pt has the best extinction efficiency and the max electric near-field intensity. And the extinction spectra of TiO<jats:sub>2</jats:sub>/Ag/Pt and TiO<jats:sub>2</jats:sub>/Ag/Au structures are complementary in the visible range. This work conduces to the further research into ternary nanostructure and provides essential information about its performance in visible range.</jats:p>

<jats:p>We study the plasmonic properties of hybrid nanostructures consisting of double vacancy defected graphene (DVDGr) and metallic nanoarrays using the time-dependent density functional theory. It is found that DVDGr with pure and mixed noble/transition-metal nanoarrays can produce a stronger light absorption due to the coherent resonance of plasmons than graphene nanostructures. Comparing with the mixed Au/Pd nanoarrays, pure Au nanoarrays have stronger plasmonic enhancement. Furthermore, harmonics from the hybrid nanostructures exposed to the combination of lasers ranged from ultraviolet to infrared and a controlling pulse are investigated theoretically. The harmonic plateau can be broadened significantly and the energy of harmonic spectra is dramatically extended by the controlling pulse. Thus, it is possible to tune the width and intensity of harmonic spectrum to achieve broadband absorption of radiation. The methodology described here not only improves the understanding of the surface plasmon effect used in a DVDGr-metal optoelectronic device but also may be applicable to different optical technologies.</jats:p>