Cartilage injury is extremely common and leads to joint dysfunction. Existing joint prostheses do not remodel with host joint tissue. However, developing large-scale biomimetic anisotropic constructs mimicking native cartilage with structural integrity is challenging. In the present study, we describe anisotropic cartilage regeneration by three-dimensional (3D) bioprinting dual-factor releasing and gradient-structured constructs. Dual-factor releasing mesenchymal stem cell (MSC)–laden hydrogels were used for anisotropic chondrogenic differentiation. Together with physically gradient synthetic biodegradable polymers that impart mechanical strength, the 3D bioprinted anisotropic cartilage constructs demonstrated whole-layer integrity, lubrication of superficial layers, and nutrient supply in deep layers. Evaluation of the cartilage tissue in vitro and in vivo showed tissue maturation and organization that may be sufficient for translation to patients. In conclusion, one-step 3D bioprinted dual-factor releasing and gradient-structured constructs were generated for anisotropic cartilage regeneration, integrating the feasibility of MSC- and 3D bioprinting–based therapy for injured or degenerative joints.

Abstract-The modular multilevel converter (MMC) is distinguished by its modularity, that is the use of standardized submodules (SMs). To enhance reliability and avoid unscheduled maintenance, it is desired that MMC can remain operational without having to shut down despite some of its SMs are failed. Particularly, in this paper, a complete fault diagnosis and tolerant control solution, including the fault detection, fault tolerance, fault localization, and fault reconfiguration, has been proposed to ride through the IGBT open-circuit failures. The fault detection method detects the fault by means of state observers and the knowledge of fault behaviors of MMC, without using any additional sensors. Then MMC is controlled in a newly proposed tolerant mode until the specific faulty SM is located by the fault localization method, thus no overcurrent problems will happen during this time interval. After that, the located faulty SM will be bypassed while the remaining SMs are reconfigured to provide continuous operation. Throughout the fault periods, it allows the MMC to operate smoothly without obvious waveform distortion and power interruption. Finally, experimental results using a single-phase scaled-down MMC prototype with six SMs per arm show the validity and feasibility of the proposed methods. Index Terms-Fault diagnosis, fault tolerance, insulated gate bipolar transistor (IGBT), modular multilevel converter (MMC), open-circuit failure, redundancy, state observer, submodule (SM).

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Confining interacting particles in one-dimension (1D) changes the electronic behavior of the system fundamentally, which has been studied extensively in the past. Examples of 1D metallic systems include carbon nanotubes, quasi-1D organic conductors, metal chains, and domain boundary defects in monolayer thick transition-metal dichalcogenides such as MoSe 2 . Here single and bundles of Mo 6 Se 6 nanowires were fabricated through annealing a MoSe 2 monolayer grown by molecular-beam epitaxy on graphene. Conversion from twodimensional (2D) MoSe 2 film to 1D Mo 6 Se 6 nanowire is reversible. Mo 6 Se 6 nanowires form preferentially at the Se-terminated zigzag edges of MoSe 2 and stitch to it via two distinct atomic configurations. The Mo 6 Se 6 wire is metallic and its length is tunable, which represents one of few 1D systems that exhibit properties pertinent to quantum confined Tomonaga−Luttinger liquid, as evidenced by scanning tunneling microscopic and spectroscopic studies.