In this work, we demonstrate that a graphene oxide (GO) hydrogel with unique rheological properties, such as high storage modulus, shear-thinning nature and fast viscosity recovery, is highly suitable as an ink for three dimensional (3D) printing. The results show that the GO ink has the characteristics of both gel and viscous liquid, where the gel-liquid transition depends on the shear rate and shear strain amplitude. In the extrusion and printing process, the ink shows significant shear thinning and rapid viscosity recovery after cessation of shearing, which are desirable for 3D printing through direct ink writing (DIW). A suitable scanning speed and extrusion speed were determined to construct a precise 3D structure. After the reduction, the RGO electrode with hierarchical porous structures is stable, of higher precision, and loaded with more of the effective materials per unit area. The 3D printed micro-supercapacitors (MSCs) with interdigitated architecture exhibit a high areal specific capacitance of 101 mF cm À2 at a current density of 0.5 mA cm À2 and 111 mF cm À2 at a scan rate of 10 mV s À1 , which are superior compared with most of the reported MSCs of carbon-based materials. Fig. 1 (a) Schematic illustration of the fabrication process of 3DHG-MSCs, (b) structural decomposition diagram of 3DHG-MSCs, (c) optical image of the 3D interdigitated architecture composed of three-pair fingers with 5 printed layers, (d) optical microscopic image of 3DHG electrode.This journal is

However, it is often challenging to print large free-form tissue structures owing to the inadequate structural integrity and mechanical stability of softhydrogel-based bioink. [4] For the past decade, considerable effort has been made to address this particular challenge. For example, Kang and co-workers proposed a hydrogel reinforcing strategy by coprinting cell-laden hydrogel bioinks with synthetic polycaprolactone (PCL) polymer that serves as a supporting framework. [5] Although this strategy allowed the fabrication of humanscale bone and cartilage tissue constructs, the mechanically robust PCL fibers often impeded the maturation of soft tissue such as the heart and liver. Alternatively, the embedded 3D bioprinting strategy has gained increasing popularity for constructing complex freeform structures. [6] In this approach, a suspension medium is utilized to support the deposition of bioinks in 3D space before crosslinking. The suspension medium undergoes rapid fluidization at yield stress and then solidification in the absence of stress due to its unique shear-thinning and self-healing properties. [7] The printed structures can easily be removed from the suspension medium by gently washing the suspension medium or raising the temperature. As an example of this strategy, Lee and co-workers printed a functional ventricle and full-size human heart model into a gelatin microparticles-based suspension medium by using a freeform reversible embedding of suspended hydrogels, also termed the FRESH technique. [8] Creating functional tissues and organs in vitro on demand is a major goal in biofabrication, but the ability to replicate the external geometry of specific organs and their internal structures such as blood vessels simultaneously remains one of the greatest impediments. Here, this limitation is addressed by developing a generalizable bioprinting strategy of sequential printing in a reversible ink template (SPIRIT). It is demonstrated that this microgel-based biphasic (MB) bioink can be used as both an excellent bioink and a suspension medium that supports embedded 3D printing due to its shear-thinning and self-healing behavior. When encapsulating human-induced pluripotent stem cells, the MB bioink is 3D printed to generate cardiac tissues and organoids by extensive stem cell proliferation and cardiac differentiation. By incorporating MB bioink, the SPIRIT strategy enables the effective printing of a ventricle model with a perfusable vascular network, which is not possible to fabricate using extant 3D printing strategies. This SPIRIT technique offers an unparalleled bioprinting capability to replicate the complex organ geometry and internal structure in a faster manner, which will accelerate the biofabrication and therapeutic applications of tissue and organ constructs.

A new coal-based polygeneration system with CO 2 recycle is proposed in this paper. With the gasified coal gas containing 23 vol % CO 2 and the coke oven gas containing 25 vol % CH 4 as the dual gas sources, the system mainly produces methanol, dimethyl ether, and electric power. The system adopts CO 2 /CH 4 reforming to modify the C/H ratio of the syngas. Particularly, the CO 2 , coming from the distillation tower, is recycled separately back to be a reactant during gasification and the resource gas in the reforming unit. As the CO 2 concentration in the exhausted gas from the distillation tower is more than 95 wt %, this system does not require a CO 2 separation unit. The system avoids the conventional water−gas shift reaction that is used to adjust the ratio of C/H in the syngas, but fully uses the CO 2 produced from coal gasification, which solves the problems of CO 2 capture and storage. The performance of the whole system's energy, CO 2 emission, and economics are analyzed by Aspen Plus 11.1 and Aspen Icarus 11.1 software. Results indicate that the new system realizes 11.5% increase of chemical energy, 1.3% increase of internal rate of return and 33.8% reduction of CO 2 emission at the expense of 8.4% of power output. Especially, the new system can save about 13−18% on energy versus single product systems. The scheme in which CO 2 is recycled back to the gasifier and the reforming unit plays the most significant role in the comprehensive evaluation of energy utilization, CO 2 emission control, and economy benefits of the system.

In order to utilize lignite in a clean and highly efficient way, an energy system for lignite pyrolysis by solid heat carrier coupled gasification is proposed in this study. The process is simulated and analyzed by Aspen Plus 11.1 on the basis of experimental data. The energy consumption distribution of the system and the mass ratio of the solid heat carrier to lignite, the most important technological parameters, are revealed. The choice of gasifier has the greatest impact on the energy efficiency of the system. Results show that, with a lignite handling capacity of 41.7 t•h −1 , the yields of tar and coal gasified gas are 1.6 and 25.7 t•h −1 , respectively, and 17% of the char is burnt to supply energy for the system while the remainder is used in the gasifier. Also, the surface moisture present in lignite and the phenol water from the tar can be utilized as the gasification agent in the coupled process, saving up to 8.9 t•h −1 water and decreasing the handling capacity of phenol water by 2.7 t•h −1 , thereby reducing the net volume of polluted water emitted by the system. It is possible for the system as a whole to achieve an energy efficiency of up to 85.8%. The study also shows that the majority of the energy used by the system is consumed during the drying and pyrolysis processes. Exploiting new technology, integrating and optimizing the energy use of the system to reduce energy consumption will be beneficial to improving the overall system performance.

Despite progress in engineering both vascularized tissues and oriented tissues, the fabrication of 3D vascularized oriented tissues remains a challenge due to an inability to successfully integrate vascular and anisotropic structures that can support mass transfer and guide cell alignment, respectively. More importantly, there is a lack of an effective approach to guiding the scaffold design bearing both structural features. Here, an approach is presented to optimize the bifurcated channels within an anisotropic scaffold based on oxygen transport simulation and biological experiments. The oxygen transport simulation is performed using the experimentally measured effective oxygen diffusion coefficient and hydraulic permeability of the anisotropic scaffolds, which are also seeded with muscle precursor cells and cultured in a custom‐made perfusion bioreactor. Symmetric bifurcation model is used as fractal unit to design the channel network based on biomimetic principles. The bifurcation level of channel network is further optimized based on the oxygen transport simulation, which is then validated by DNA quantification assay and pimonidazole immunostaining. This study provides a practical guide to optimizing bifurcated channels in anisotropic scaffolds for oriented tissue engineering.