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Aluminum-substituted M-type strontium hexaferrite (SrM-Al, SrFe12−xAlxO19, 0 ≤ x ≤ 4) with uniform microstructure and excellent magnetic properties was synthesized by conventional ceramic processing based on solid state reaction. Coercive field was highly enhanced by heavy doping with Al3+ although magnetization was significantly reduced. However, formation of coarse microstructure and poor development of Hc with low level doping of Al3+ disturbed practical application. To promote phase formation and to suppress growth of coarse grains which were induced by incorporation of Al3+ ions, SrM-Al ceramics was processed with NaOH. Such Na-assisted processing of SrM-Al reduced formation of non-magnetic phases and assisted development of uniform fine grains. In addition, the large residual strain by Al3+ doping was partially relieved by the same approach. As a result, saturation magnetization of SrFe12−xAlxO19 was remarkably enhanced and the BHmax of randomly oriented hard magnetic ceramics was improved to 1.23MGOe by concomitant addition of Na and Al ions.

We studied the structural and magnetic properties of BaFe

Scale-up of synthesis process is highly required for commercial application of quantum dots (QDs). Although batch-type hot injection method is most popular synthesis route for QDs, its commercial scale-up version only gives non-uniform and less luminescent QDs with broad size distribution. In this study, we introduce a novel and facile method of large-scale synthesis of QDs using a fluid-dynamically controlled reactor, Taylor-Couette reactor (TCR). We successfully synthesized CdSe QDs with TCR and as-synthesized QDs were capped with epitaxial CdS layers using the molecular precursors for enhanced luminescence. The synthesis process was stabilized after 20 min from the start of initial injection of precursors and standard deviation of luminescence wavelength and spectral linewidth was less than 1 nm. After shell capping process based on pyrolysis of Cd-diethyldithiocarbamate, CdSe QDs synthesized from continuous processing route based on TCR showed intense photoluminescence at 640 nm with a spectral linewidth of 33 nm, which is much narrower than PL spectra of QDs synthesized from conventional batch-type synthesis route using reaction vessel with large volume capacity. We demonstrated high throughput synthesis of highly luminescent CdSe QDs using TCR as a platform for continuous synthesis with very large production yield (22,560 kg‧day−1‧m−3 in space-time yield).

The drawbacks of conventional drug administration include repeated administration, non-specific biodistribution in the body's systems, the long-term unsustainability of drug molecules, and high global cytotoxicity, posing a challenge for the efficient treatment of chronic diseases that require varying drug dosages over time for optimal therapeutic efficacy. Most controlled-release methods encapsulate drug molecules in biodegradable materials that dissolve over time to release the drug, making it difficult to deliver drugs on a schedule. To address these limitations, we developed a magneto-, opto-stimuli responsive drug delivery system based on functionalized electrospun nanofibers loaded with superparamagnetic iron oxide nanoparticles (SPIONs). We exploited the Neel relaxation effect of SPIONs, where heat generated from vibrating SPIONs under exogenously applied magnetic fields or laser illumination induced structural changes of the thermo-sensitive nanofibers that encapsulate the particles. We showed that this structural change of nanofibers is the governing factor in controlling the release of dye molecules, used as a model drug and co-encapsulated within the nanofibers. We also showed that the degree of nanofiber structural change depends on SPION loading and duration of stimulation, demonstrating the tunability of the drug release profile. Overall, we demonstrated the potential of SPION-embedded thermoplastic nanofibers as an attractive platform for on-demand drug delivery.

We developed linearly linked spherical fillers in polymer composites with incorporating Al2O3-Fe3O4 hybrid particles under a magnetic field to form thermal networks for high thermal conductivity. The Al2O3-Fe3O4 hybrid particles were prepared by a simple precipitation method and their magnetic properties were characterized with magnetic hysteresis. The Al2O3-Fe3O4 hybrid particles were well aligned through direction of magnetic field as confirmed by microscopic observation. The polymer composites obtained with Al2O3-Fe3O4 hybrid particles possessed high thermal conductivity in a parallel magnetic alignment direction at low filler loading, which is more than 240% outperformed the composites with randomly dispersed fillers.

Efficient heat transport along through-plane direction is one of the primary requisites for thermal interface materials (TIMs) to relieve heat accumulation at the interface between chip and heat sinks. We report enhanced thermal conduction of Al 2 O 3 -based polymer composites by surface wetting and texturing of thermally conductive hexagonal boron nitride (h-BN) nanoplatelets with large anisotropy (diameter 2 O 3 macrobeads and surface modified h-BN nanoplatelets. Here, the clustering or assembly of h-BN nanoplatelets is analyzed based on depletion interaction of colloidal particles. In addition, further addition of minimal amount of SiO 2 nanoparticles shows a drastic improvement of thermal transport properties, which is attributed to the depletion interaction between nanoplatelets mediated by spherical nanoparticles. Here, the benefits of surface wetting for thermal management composite materials are illustrated.

Highly luminescent boron nitride (BN) was synthesized by pyrolysis of molecular adduct prepared by chemical mixing of boric acid and melamine with a small amount of cerium nitrate. After pyrolysis, Ce ions were substitutionally incorporated to B3N3 hexagonal layer of turbostratic BN at a very low doping level which was estimated to be less than 7 × 1018 atoms/cm3. Ordered stacking of hexagonal layers along c-axis of BN or transformation of turbostratic BN to hexagonal BN was induced by addition of Ce ions even though the amount of Ce ions surpassed substitutional doping limits. The intense photoluminescence (PL) spectrum of Ce-doped BN was detected at 390 nm by excitation of UV light (λ = 314 nm) and PL intensity was improved with increasing level of Ce addition following the enhanced crystallinity of turbostratic BN. The origin of UV-emission was ascribed to the transition from the crystal field components of the 5d level to the 4f ground states of the Ce3+ ion.