The investigation of the fluorescence mechanism of carbon dots (CDs) has attracted significant attention, particularly the role of the oxygen-containing groups. Dual-CDs exhibiting blue and green emissions are synthesized from glucose via a simple ultrasonic treatment, and the oxidation degree of the CDs is softly modified through a slow natural oxidation approach, which is in stark contrast to that aggressively altering CDs’ surface configurations through chemical oxidation methods. It is interesting to find that the intensity of the blue fluorescence gradually increases, eventually becoming the dominant emission after prolonging the oxidation periods, with the quantum yield (QY) of the CDs being enhanced from ~0.61% to ~4.26%. Combining the microstructure characterizations, optical measurements, and ultrafiltration experiments, we hypothesize that the blue emission could be ascribed to the surface states induced by the C–O and C=O groups, while the green luminescence may originate from the deep energy levels associated with the O–C=O groups. The distinct emission states and energy distributions could result in the blue and the green luminescence exhibiting distinct excitation and emission behaviors. Our findings could provide new insights into the fluorescence mechanism of CDs.

This study aimed to elucidate the molecular mechanisms, whereby hyaluronic acid, a main extracellular matrix component of articular cartilage, promotes the chondrogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs). Our previous findings indicated that hyaluronic acid combined with hAMSCs showed a marked therapeutic effect against rat osteoarthritis. In the present study, hyaluronic acid markedly enhanced the expression of chondrocyte-specific markers including Col2α1, Acan, and Sox9 in hAMSCs, with strong synergistic effects on chondrogenic differentiation, in combination with the commonly used inducer, transforming growth factor β3 (TGF-β3). Microarray analysis showed that Ras-like protein family member 11B (RASL11B) played a pivotal role in the process of hyaluronic acid-mediated chondrogenesis of hAMSCs. This directional differentiation was significantly inhibited by RASL11B knockdown, but RASL11B overexpression dramatically promoted the expression of Sox9, a master chondrogenesis transcriptional factor, at the levels of transcription and translation. Increased Sox9 expression subsequently resulted in high expression levels of Col2α1 and Acan and the accumulation of cartilage-specific matrix components, such as type 2 collagen and glycosaminoglycans. Moreover, we observed that RASL11B activated the signal molecules such as ERK1/2, and Smad2/3 in the presence of hyaluronic acid during TGF-β3-induced chondrogenesis of hAMSCs. Taken together, these findings suggest that hyaluronic acid activates the RASL11B gene to potentiate the chondrogenic differentiation of hAMSCs via the activation of Sox9 and ERK/Smad signaling, thus providing a new strategy for cartilage defect repairing by hyaluronic acid-based stem cell therapy.

Developing efficient power-splitting device for multichannel distributed low-frequency (LF) mechanical antenna (MA) communication system is challenging since conventional LF power-splitting technologies rely on lumped resistive elements with unsatisfied efficiency and poor electrical isolation. In view of this, a magnetoelectric (ME) power splitter consisting of nickel–zinc ferrite and Rosen-type piezoelectric transformer composite was modeled, fabricated, and packaged with a supporting theory to quantitatively describe the power-splitting ratio. To reveal the energy loss between interlayers, a noncontact optical Doppler measurement was employed to track the energy losses between interlayers. Results show that favorable input-to-output isolation with a high insulation voltage of 2.35 kV in the packaged device was obtained, and the maximum PE for Port I and Port II reached 34.45% and 35.87% at R _L = 1 kΩ and R _L = 13 kΩ, respectively, in tailored sample with thickness ratio of n _p = 0.412, and then the measured splitting ratio approximates 1.1 and matches well with the theoretical predictions. Finally, the proposed ME splitter was deployed in a dual-channel distributed LF communication system for implementing each MA excitation, the system divided one source into two independent transmitting ME antennas and accomplished 20 bps amplitude shift keying modulated signal delivery to searching coils under a distance of 125 cm and an input power of 3.57 mW.

A new idea was provided by the group-IV GeSn alloys for short-wave infrared light source compatible with CMOS due to the low cost integrated on the Si platform and can be transformed into direct bandgap alloy. More than 7.1% Sn content or strain engineering is used to achieve the direct bandgap GeSn semiconductors and enhance the luminous efficiency of GeSn light-emitting devices. We theoretically investigate a strain-adjustable GeSn light-emitting diode with the giant magnetostrictive stressor. A 0 ∼ 0.11% adjustable uniaxial tensile strain is introduced into Ge _0.92 Sn _0.08 LED by adjusting the external magnetic field. A continuously adjustable bandgap from 0.543 eV to 0.475 eV of the Ge _0.92 Sn _0.08 alloy is achieved in the magnetic field intensity range of 0 ∼ 240 kA/m, and the spontaneous emission rate of the strained LED is enhanced about 3.63 times compared with the relaxed device. Besides, an adjustable range of luminous peak is achieved from 2.18 μm to 2.46 μm, which can promote the application of GeSn light source for magnetic field detection and photo-communication in short-wave infrared.

Germanium tin (GeSn) is group IV alloys with a high carrier mobility and tunable energy bandgap. GeSn alloys with high crystallinity were epitaxially grown on Ge and Si substrates using solid source molecular beam epitaxy at very low temperature. Undoped Ge_0.92Sn_0.08 quantum well p-channel MOSFETs with in-situ Si₂H₆ passivation has been fabricated and the devices demonstrate a high effective hole mobility of 693 cm² V^–1 s^–1. Impact of Sn composition on performance of GeSn MOSFETs is also investigated. We also introduce strain engineering used in GeSn photodetector for mid-infrared applications. A novel strained Ge_0.90Sn_0.10 photodetector with fin structures wrapped in Si₃N₄ liner stressor was designed. With biaxial tensile strain induced by Si₃N₄ liner stressor, the cut-off wavelength of Ge_0.90Sn_0.10 fin photodetectors is extended to 4 μm.