The platelet-rich fibrin (PRF) is known as a rich source of autologous cytokines and growth factors and universally used for tissue regeneration in current clinical medicine. However, the microstructure of PRF has not been fully investigated nor have been studied the key molecules that differ PRF from platelet-rich plasma. We fabricated PRF under Choukroun's protocol and produced its extract (PRFe) by freezing at À808C. The conventional histological, immunohistological staining, and scanning electron microscopy images showed the microstructure of PRF, appearing as two zones, the zone of platelets and the zone of fibrin, which resembled a mesh containing blood cells. The PRFe increased proliferation, migration, and promoted differentiation of the human alveolar bone marrow stem cells (hABMSCs) at 0.5% concentration in vitro. From the results of proteome array, matrix metalloproteinase 9 (MMP9) and Serpin E1 were detected especially in PRFe but not in concentrated platelet-rich plasma. Simultaneous elevation of MMP9, CD44, and transforming growth factor b-1 receptor was shown at 0.5% PRFe treatment to the hABMSC in immunoblot. Mineralization assay showed that MMP9 directly regulated mineralization differentiation of hABMSC. Transplantation of the fresh PRF into the mouse calvarias enhanced regeneration of the critical-sized defect. Our results strongly support the new characteristics of PRF as a bioscaffold and reservoir of growth factors for tissue regeneration.

The catalytic activity for the hydrogen evolution reaction (HER) at the anion vacancy of 40 2D transition-metal dichalcogenides (TMDs) is investigated using the hydrogen adsorption free energy (Δ G) as the activity descriptor. While vacancy-free basal planes are mostly inactive, anion vacancy makes the hydrogen bonding stronger than clean basal planes, promoting the HER performance of many TMDs. We find that ZrSe and ZrTe have similar Δ G as Pt, the best HER catalyst, at low vacancy density. Δ G depends significantly on the vacancy density, which could be exploited as a tuning parameter. At proper vacancy densities, MoS, MoSe, MoTe, ReSe, ReTe, WSe, IrTe, and HfTe are expected to show the optimal HER activity. The detailed analysis of electronic structure and the multiple linear regression results identifies the vacancy formation energy and band-edge positions as key parameters correlating with Δ G at anion vacancy of TMDs.

We perform first-principles calculations to investigate the electronic and vibrational spectra and the electron mobility of β-GaO. We calculate the electron-phonon scattering rate of the polar optical phonon modes using the Vogl model in conjunction with Fermi's golden rule; this enables us to fully take the anisotropic phonon spectra of the monoclinic lattice of β-GaO into account. We also examine the scattering rate due to ionized impurities or defects using a Yukawa-potential-based model. We consider scattering due to donor impurities, as well as the possibility of compensation by acceptors such as Ga vacancies. We then calculate the room-temperature mobility of β-GaO using the Boltzmann transport equation within the relaxation time approximation, for carrier densities in the range from 10 to 10 cm. We find that the electron-phonon interaction dominates the mobility for carrier densities of up to 10 cm. We also find that the intrinsic anisotropy in the mobility is small; experimental findings of large anisotropy must therefore be attributed to other factors. We attribute the experimentally observed reduction of the mobility with increasing carrier density to increasing levels of compensation, which significantly affect the mobility.

Zinc‐based metal oxide semiconductors have attracted attention as an alternative to current silicon‐based semiconductors for applications in transparent and flexible electronics. Despite this, metal oxide transistors require significant improvements in performance and electrical reliability before they can be applied widely in optoelectronics. Amorphous indium–zinc–tin oxide (a‐IZTO) has been considered an alternative channel layer to a prototypical indium–gallium–zinc oxide (IGZO) with the aim of achieving a high mobility (>40 cm2 Vs−1) transistors. The effects of the gate bias and light stress on the resulting a‐IZTO field‐effect transistors are examined in detail. Hydrogen impurities in the a‐IZTO semiconductor are found to play a direct role in determining the photo‐bias stability of the resulting transistors. The Al2O3‐inserted IZTO thin‐film transistors (TFTs) are hydrogen‐poor, and consequently show better resistance to the external‐bias‐thermal stress and photo‐bias‐thermal stress than the hydrogen‐rich control IZTO TFTs. First‐principles calculations show that even in the amorphous phase, hydrogen impurities including interstitial H and substitutional H can be bistable centers with an electronic deep‐to‐shallow transition through large lattice relaxation. The negative threshold voltage shift of the a‐IZTO transistors under a negative‐bias‐thermal stress and negative‐bias‐illumination stress condition is attributed to the transition from the acceptor‐like deep interstitial Hi− (or substitutional H‐DX−) to the shallow Hi+ (or HO+) with a high (low) activation energy barrier. Conclusively, the delicate controllability of hydrogen is a key factor to achieve the high performance and stability of the metal oxide transistors.

BaSnO3 (BSO) is a promising transparent conducting oxide (TCO) with reported roomtemperature (RT) Hall mobility exceeding 320 cm 2 V −1 s −1 . Among perovskite oxides, it has the highest RT mobility, about 30 times higher than that of the prototypical SrTiO3. Using firstprinciples calculations based on hybrid density functional theory, we elucidate the physical mechanisms that govern the mobility by studying the details of LO-phonon and ionized impurity scattering. A careful numerical analysis to obtain converged results within the relaxation-time approximation of Boltzmann transport theory is presented. The k dependence of the relaxation time is fully taken into account. We find that the high RT mobility in BSO originates not only from a small effective mass, but also from a significant reduction in the phonon scattering rate compared to other perovskite oxides; the origins of this reduction are identified. Ionized impurity scattering influences the total mobility even at RT for dopant densities larger than 5 × 10 18 cm −3 , and becomes comparable to LO-phonon scattering for 1 × 10 20 cm −3 doping, reducing the drift mobility from its intrinsic LO-phonon-limited value of ∼594 cm 2 V −1 s −1 to less than 310 cm 2 V −1 s −1 . We suggest pathways to avoid impurity scattering via modulation doping or polar discontinuity doping. We also explicitly calculate the Hall factor and Hall mobility, allowing a direct comparison to experimental reports for bulk and thin films and providing insights into the nature of the dominant mechanisms that limit mobility in state-of-the art samples.

Inorganic cesium-lead-halide perovskites (CsPbX 3 , where X = Cl, Br, and I) have recently emerged as promising semiconductors for photovoltaic and light-emitting devices. In this study, we investigate electronic and vibrational properties of CsPbX 3 using the density-functional-theory calculations. We explicitly evaluate k-dependent electron-phonon scattering rates of the polar longitudinal-optical phonon modes. The transport property at room temperature is then computed based on Boltzmann transport theory within the relaxation-time approximation. The computational results identify the fundamental limit of the carrier mobility and its dependence on the halide species. Our results show that different choices of X lead to the variation in the mobility by a factor of 3 to 5 depending on the carrier concentration between 10 15 and 10 18 cm −3 . The preferred carrier type (electron or hole) in terms of the mobility also varies with X . Through the detailed analysis on the band structures and scattering rates, we provide insights into the role of halide species in the transport properties.

This study examined the performance and photo-bias stability of double-channel ZnSnO/InZnO (ZTO/IZO) thin-film transistors. The field-effect mobility (μFE) and photo-bias stability of the double-channel device were improved by increasing the thickness of the front IZO film (tint) compared to the single-ZTO-channel device. A high-mobility (approximately 32.3 cm2/Vs) ZTO/IZO transistor with excellent photo-bias stability was obtained from Sn doping of the front IZO layer. First-principles calculations revealed an increase in the formation energy of O vacancy defects in the Sn-doped IZO layer compared to the IZO layer. This observation suggests that the superior photo-bias stability of the double-channel device is due to the effect of Sn doping during thermal annealing. However, these improvements were observed only when tint was less than the critical thickness. The rationale for this observation is also discussed based on the oxygen vacancy defect model.

Using the multiscale simulation combining ab initio calculations and kinetic Monte Carlo (KMC) simulations, we theoretically investigate the hydrogen evolution reaction (HER) on the sulfur vacancy of a MoS 2 monolayer. Unlike metal catalysts, the protonation step and the charging step proceed independently in semiconducting MoS 2 . Interestingly, the barrier for hydrogen evolution decreases when the vacancy site is hyper-reduced with extra electrons. The turnover frequency and polarization curve obtained from the KMC simulation agree well with extant experimental data, and the major HER paths underscore the role of hyper-reduced states, particularly when the overpotential is applied. The strain effect is also simulated, and it is found that the tensile strain enhances HER by reducing the energy cost of hyper-reduced states. The estimated reduction in the overpotential agrees favorably with the experiment while the hydrogen binding energy alone cannot account for it, suggesting that the full-blown KMC simulation should be used to accurately predict the variation of HER performance under various conditions. By uncovering the nature of the catalytic reaction at the sulfur vacancy of MoS 2 and revealing a design principle in which the facile formation of hyper-reduced states plays an important role, the present work will pave the way for developing HER catalysts that may replace Pt.