No abstract

In order to understand the physical properties of materials it is necessary to determine the 3D positions of all atoms. There has been significant progress towards this goal using electron tomography. However, this method requires a relatively high electron dose and often extended acquisition times which precludes the study of structural dynamics such as defect formation and evolution. In this work we describe a method that enables the determination of 3D atomic positions with high precision from single high resolution electron microscopic images of graphene that show dynamic processes. We have applied this to the study of electron beam induced defect coalescence and to long range rippling in graphene. The latter strongly influences the mechanical and electronic properties of this material that are important for possible future applications.

Owing to its superior bioactivity, biocompatibility, and biodegradability, bioactive glass (BG) has been attracting significant attention within biomedical science fields. However, BG powders with variable particle sizes are required targeting different applications, such as dermal fillers. Thus, in this study, granulated BG powders were prepared via the spray drying and granulation method. Size‐controlled BG micron sphere with diameters of up to tens of microns can be mass‐produced and their phase information, particle morphology, and specific surface area were characterized via X‐ray diffraction, scanning electron microscopy, and nitrogen adsorption/desorption isotherm, respectively. In addition, the in vitro bioactivity was evaluated following Kokubo's protocol, and the formation of a hydroxyapatite (HA) layer after immersion into the simulated body fluid was confirmed via energy‐dispersive and Fourier transform infrared spectroscopy. The cytotoxicity was examined using a 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide assay. Finally, the resulting morphologies and corresponding properties are shown, and the related mechanisms are discussed.

Chou (2021): Fabrication and characterization of freeze dried strontium-doped bioactive glasses/chitosan composite scaffolds for biomedical engineering, Journal of Asian Ceramic Societies,

Bioactive glass (BG) has been regarded as an excellent candidate for biomedical applications due to its superior properties of bioactivity, biocompatibility, osteoconductivity and biodegradability. Thus, in this study, we aimed to fabricate drug carriers that were capable of loading therapeutic antibiotics while promoting bone regeneration using macroporous BG microspheres, prepared by a spray drying method. Characterizations of particle morphology and specific surface area were carried out via scanning electron microscopy and nitrogen adsorption/desorption isotherm. Evaluations of in vitro bioactivity were performed based on Kokubo’s simulated body fluid to confirm the formation of the hydroxyapatite (HA) layer after immersion. In addition, the in vitro drug release behaviors were examined, using tetracycline as the therapeutic antibiotic in pH 7.4 and 5.0 environments. Finally, the results showed that BG microspheres of up to 33 μm could be mass-produced, targeting various therapeutic situations and their resulting bioactivities and drug release behaviors, and related properties were discussed.