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Although great progress has been made in coaxial extrusion printing toward generating microtubes for mimicking tubular tissues, these microtubes with insufficient mechanical properties and uncontrollable inherent swelling attribute severely hinder their utilization as load-bearing tubular tissue. Herein, a high-strength microtube is constructed by coaxial printing with a customized biohybird hydrogel ink consisting of nanoclay, H-bonding mono mer N-acryloyl glycinamide, and gelatin methacryloyl. The physical interpenetration between nanoclay and polymer chains endows this ink with excellent printability and structural stability, thus facilitating the precise deposition of scalable microtubes with tunable small-diameters and large-scale lengths. After photocrosslinking, 3D-printed biohybrid hydrogel microtube demonstrates marvelous mechanical properties with a tensile strength (≈22 MPa), a stretchability (≈500%), a Young's modulus (≈21 MPa), an anti-fatigue performance (≈200 cycles), a burst pressure (≈2500 mmHg), and a suture retention strength (≈280 gf) in swelling equilibrium state, which are far superior to the previously printed microtubes and generally satisfy the requirements of tubular tissues. Additionally, this obtained microtube also displays favorable biological features that support adhesion, spreading, and endothelialization of human umbilical vein endothelial cells. This study successfully develops a biohybrid hydrogel ink to fabricate a scalable high-strength microtube with enormous potential in regeneration of tube-like tissues.

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The characteristics of a tunnel quantum dot intersublevel photodetector, designed for the absorption of terahertz radiation, are described. The absorption region consists of self-organized In 0.6 Al 0.4 As/ GaAs quantum dots with tailored electronic properties. Devices exhibit spectral response from 20 to 75 m ͑ϳ4 THz͒ with peak at ϳ50 m. The peak responsivity and specific detectivity of the device are 0.45 A / W and 10 8 cm Hz 1/2 / W, respectively, at 4.6 K for an applied bias of 1 V. Response to terahertz radiation is observed up to 150 K.

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Satisfactory repair of damaged articular cartilage is still a challenge, while tissue engineering provides a promising strategy. Collagen-based hydrogels have been widely applied in cartilage tissue engineering due to their biocompatibility. In this study, type I collagen and type II collagen were selected to prepare physically crosslinked composite hydrogels by self-assembly of collagen, and the effects of their physicochemical properties on chondrocyte phenotype maintenance and extracellular matrix (ECM) secretion were investigated. First, the microstructure of hydrogels was observed by a scanning electron microscope, and the compressive modulus was measured by a dynamic mechanical analyzer. Then, chondrocytes were encapsulated in hydrogels and detected by Live/Dead staining. The secretion of ECM was qualitatively estimated by histological staining and quantitatively analyzed by sulfated glycosaminoglycans and DNA content detection. Finally, cartilage-specific gene expression was analyzed by quantitative real-time polymerase chain reaction analysis. The results showed that the microstructure and mechanical property of hydrogels were relevant to the composition of composite hydrogels. The compressive modulus of hydrogels improved with the increase of type I collagen content in the hydrogels. Chondrocytes could maintain their round or oval morphology and secrete cartilage-specific ECM in the four groups of hydrogels, but higher the compressive modulus of composite hydrogels, the more ECM secretion of chondrocytes.

We demonstrate the generation of broadband THz pulses by optical rectification in GaP waveguides pumped by high power Yb-doped fiber amplifiers. The dispersion of the GaP emitter can be controlled via the geometry of the waveguide; the peak frequency of the emitted THz radiation is tuned by varying the waveguide cross-section. Most importantly, the use of a waveguide for the THz emission increases the coherent buildup length of the THz pulses and offers scalability to higher power; this was investigated by pumping a GaP waveguide emitter with a high power Yb-doped fiber laser system. A 25-MHz-repetition-rate pulse train of THz radiation with 120 muW average power was achieved using 14 W optical power, which represents the highest average power for a broadband THz source pumped by fiber lasers to date.