Hydroxyapatite
is the main inorganic component of human bone. Synthetic
hydroxyapatite and its different modified forms, which have been shown
to be biocompatible and osteoconductive, have been widely used in
bone tissue engineering. It is still challenging to controllably synthesize
hydroxyapatite with a targeted morphology. In this work, we synthesized
highly crystalline selenium-doped hydroxyapatite nanorods (SeHAN)
via a two-step alcohol thermal method and provided a complete explanation
of the synthesis mechanism. Tracing the crystals obtained from the
solvated phase to the crystal phase with high-resolution microscopy,
the nanorod formation route can be briefly described as follows: as
a basic unit, ∼30 nm amorphous apatite initially formed in
the first step and partly crystallized in early part of the second
step; after a period of alcohol thermal reaction, immature nanorods
appeared, which were composed of nanocrystals; finally, immature nanorods
transformed into single-crystal nanorods through crystallization by
particle attachment. Since few works have focused on the osteogenesis
ability of SeHAN, whose antitumor effect has been widely studied,
we investigated the influences of SeHAN on rat-bone-marrow-resident
mesenchymal stem cells (MSCs). Surprisingly, SeHAN exhibited excellent
biocompatibility for MSCs, enhanced their osteogenic differentiation,
and inhibited their adipogenic differentiation. This work provides
not only a general method to controllably synthesize hydroxyapatite
nanorods/SeHAN but also an insight into understanding the hydroxyapatite
formation mechanism. The current study also highlights the effects
of SeHAN on MSCs that could furnish a significative strategy for manufacturing
functional biomaterials for biomedical applications and tissue engineering
by enhanced ossification and reduced marrow adiposity.
A real-time qualitative and quantitative polymerase chain reaction method (cer-194) using the fluorescence dye EvaGreen and aimed at the cytochrome b sequence was established for detection of cervidae DNA in feedstuff. Eight meat meal samples derived from deer, bovine, ovine, camel, pig, rabbit, fish, and chicken and 17 cervidae hair samples covering 2 subfamilies, 4 genera, and 7 species were tested to prove the specificity of the cer-194 system and its universality within the cervidae family. Detection limit of 0.1 deer meat in fish meal, blood powder, and feather powder matrixes was confirmed.
We present the ionospheric disturbance responses over low-latitude regions by using total electron content from Geostationary Earth Orbit (GEO) satellites of the BeiDou Navigation Satellite System (BDS), ionosonde data and Swarm satellite data, during the geomagnetic storm in August 2018. The results show that a prominent total electron content (TEC) enhancement over low-latitude regions is observed during the main phase of the storm. There is a persistent TEC increase lasting for about 1–2 days and a moderately positive disturbance response during the recovery phase on 27–28 August, which distinguishes from the general performance of ionospheric TEC in the previous storms. We also find that this phenomenon is a unique local-area disturbance of the ionosphere during the recovery phase of the storm. The enhanced foF2 and hmF2 of the ionospheric F2 layer is observed by SANYA and LEARMONTH ionosonde stations during the recovery phase. The electron density from Swarm satellites shows a strong equatorial ionization anomaly (EIA) crest over the low-latitude area during the main phase of storm, which is simultaneous with the uplift of the ionospheric F2 layer from the SANYA ionosonde. Meanwhile, the thermosphere O/N2 ratio shows a local increase on 27–28 August over low-latitude regions. From the above results, this study suggests that the uplift of F layer height and the enhanced O/N2 ratio are possibly main factors causing the local-area positive disturbance responses during the recovery phase of the storm in August 2018.
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