One-dimensional ZnMn2O4 nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn2O4 nanowires about 15 nm in width and 500 nm in ...length showed a high specific capacity of about 650 mAh.g-1 at a current rate of 100 mA.g-1 after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh.g 1 at current rates of 500 and 1000 mA.g 1, respectively. Formation of Mn3O4 and ZnO phases was identified by ex situ X-ray diffraction （XRD） and transmission electron microscopy （TEM） studies after the initial discharge-charge cycle, which indicates that the ZnMn2O4 phase was converted to a nanocomposite of Mn3O4 and ZnO phases immediately after the electrochemical conversion reaction.
In this work, we present a true 3D 128 Gb 2 bit/cell vertical-NAND (V-NAND) Flash product for the first time. The use of barrier-engineered materials and gate all-around structure in the 3D V-NAND ...cell exhibits advantages over 1 × nm planar NAND, such as small Vth shift due to small cell coupling and narrow natural Vth distribution. Also, a negative counter-pulse scheme realizes a tightly programmed cell distribution. In order to reduce the effect of a large WL coupling, a glitch-canceling discharge scheme and a pre-offset control scheme is implemented. Furthermore, an external high-voltage supply scheme along with the proper protection scheme for a high-voltage failure is used to achieve low power consumption. The chip accomplishes 50 MB/s write throughput with 3 K endurance for typical embedded applications. Also, extended endurance of 35 K is achieved with 36 MB/s of write throughput for data center and enterprise SSD applications.
Operando analyses have provided several breakthroughs in the construction of high‐performance materials and devices, including energy storage systems. However, despite the advances in electrode ...engineering, the formidable issues of lithium intercalation and deintercalation kinetics cannot be investigated by using planar observations. This study concerns side‐view operando observation by optical microscopy of a graphite anode based on its color changes during electrochemical lithiation. Since the graphite color varies according to the optical energy gap during lithiation and delithiation, this technique can be used to study the corresponding charge–discharge kinetics. In addition, the cell configuration uses liquid electrolytes similar to commercial cells, allowing practical application. Furthermore, this side‐view observation has shown that microscale spatial variations in rate and composition control the insertion and deinsertion, revealing the kinetics throughout the whole electrode. The results of this study could enhance the fundamental understanding of the kinetics of battery materials.
A certain point of view: Graphite color varies according to the optical energy gap during lithiation and delithiation, and this can be used to study the corresponding charge–discharge kinetics. Side‐view observation shows that microscale spatial variations in rate and composition control the insertion and deinsertion, revealing the kinetics throughout the whole electrode.
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•Freestanding nanofiber film collected using a circle electrode collector.•Easy transfer process of freestanding nanofiber film onto a non-planar surface.•Numerical studies were ...performed to investigate an electric field during electrospinning.•High productivity and uniform nanofiber film fabrication process.•Application to multifunctional filter for dust filtration and humidity blocking.
Here, we investigate a circle electrode in the electrospinning process for the fabrication of substrate-free, freestanding nanofiber films. Circle electrode-based electrospinning is controlled by varying the applied voltage and the metal needle tip-to-collector distance. The equipment used for the voltage source and syringe pump is the same as those in traditional electrospinning. A hollow cylinder is used as the circle electrode to ensure stable electrostatic conditions on the top surface of the cylinder collector. Many studies of electrospinning have presented parameters for optimal film fabrication that are inadequate for film fabrication on wire electrode-based electrospinning. To overcome obstacles inherent to substrate-free film fabrication, the voltage and tip-to-collector distance are controlled in the circle electrode-based electrospinning process. Numerical simulation is used to determine the electric field in the electrospinning process for quantitative analysis. Under voltages of 6–18 kV and tip-to-collector distances of 30–100 mm, a freestanding film is successfully fabricated on a circle electrode with 20-mm inner diameter. The freestanding electrospun film can be transferred as a coating to a non-planar surface without using additional processes. Thus, the electrospinning process using the circle electrode collector was successfully optimized for freestanding film fabrication. Substrate-free electrospun films can be applied to multifunctional filters for dust filtration with humidity blocking. Regarding future applications, the circle electrode-based electrospinning process verified the potential for integrating freestanding electrospun films into organs-on-chip, biochemical sensors, and microfluidic analysis systems.
Three-dimensionally porous carbon nanostructures have been widely used in energy storage applications owing to their large specific surface areas and excellent electrical properties. In addition, ...copper oxide has been considered as an effective pseudocapacitive material to significantly increase the energy density. In this paper, we introduce the synergetic combination of one-dimensional copper oxide nanowires and two-dimensional graphene sheets to fabricate a highly porous and electrically conductive three-dimensional hybrid nanostructure for high-performance supercapacitor electrodes with increased capacitances. The copper oxide nanowires were synthesized by reduction of copper nitrate and sequential oxidation at a high temperature. The copper oxide nanowire/graphene hybrid three-dimensional nanostructure was obtained by a self-assembly technique through a simple hydrothermal treatment. The hybrid nanostructure had an acceptable surface area and increased thermal stability. The porous hybrid nanostructure utilized as a supercapacitor electrode provided 1.6 times higher electrochemical capacitance than that of a graphene-only nanostructure-based electrode as well as superior capacitance stability with a retention of 91.2% retention after 5,000 charge−discharge cycles. Owing to the increased capacitance, the manufactured electrode exhibited high a specific energy density of 50.6 Wh kg−1 at a power density of 200 W kg−1, which demonstrates its potential for use in electrochemical energy storage devices.
Three-dimensional integrated organ printing (IOP) technology seeks to fabricate tissue constructs that can mimic the structural and functional properties of native tissues. This technology is ...particularly useful for complex tissues such as those in the musculoskeletal system, which possess regional differences in cell types and mechanical properties. Here, we present the use of our IOP system for the processing and deposition of four different components for the fabrication of a single integrated muscle-tendon unit (MTU) construct. Thermoplastic polyurethane (PU) was co-printed with C2C12 cell-laden hydrogel-based bioink for elasticity and muscle development on one side, while poly( -caprolactone) (PCL) was co-printed with NIH 3T3 cell-laden hydrogel-based bioink for stiffness and tendon development on the other. The final construct was elastic on the PU-C2C12 muscle side (E = 0.39 0.05 MPa), stiff on the PCL-NIH 3T3 tendon side (E = 46.67 2.67 MPa) and intermediate in the interface region (E = 1.03 0.14 MPa). These constructs exhibited >80% cell viability at 1 and 7 d after printing, as well as initial tissue development and differentiation. This study demonstrates the versatility of the IOP system to create integrated tissue constructs with region-specific biological and mechanical characteristics for MTU engineering.
Solid-state flexible energy storage devices hold the key to realizing portable and flexible electronic devices. Achieving fully flexible energy storage devices requires that all of the essential ...components (i.e., electrodes, separator, and electrolyte) with specific electrochemical and interfacial properties are integrated into a single solid-state and mechanically flexible unit. In this study, we describe the fabrication of solid-state flexible asymmetric supercapacitors based on an ionic liquid functionalized-chemically modified graphene (IL-CMG) film (as the negative electrode) and a hydrous RuO(2)-IL-CMG composite film (as the positive electrode), separated with polyvinyl alcohol-H(2)SO(4) electrolyte. The highly ordered macroscopic layer structures of these films arising through direct flow self-assembly make them simultaneously excellent electrical conductors and mechanical supports, allowing them to serve as flexible electrodes and current collectors in supercapacitor devices. Our asymmetric supercapacitors have been optimized with a maximum cell voltage up to 1.8 V and deliver a high energy density (19.7 W h kg(-1)) and power density (6.8 kW g(-1)), higher than those of symmetric supercapacitors based on IL-CMG films. They can operate even under an extremely high rate of 10 A g(-1) with 79.4% retention of specific capacitance. Their superior flexibility and cycling stability are evident in their good performance stability over 2000 cycles under harsh mechanical conditions including twisted and bent states. These solid-state flexible asymmetric supercapacitors with their simple cell configuration could offer new design and fabrication opportunities for flexible energy storage devices that can combine high energy and power densities, high rate capability, and long-term cycling stability.
Bioprinting technology and its applications Seol, Young-Joon; Kang, Hyun-Wook; Lee, Sang Jin ...
European journal of cardio-thoracic surgery,
09/2014, Letnik:
46, Številka:
3
Journal Article
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Bioprinting technology has emerged as a powerful tool for building tissue and organ structures in the field of tissue engineering. This technology allows precise placement of cells, biomaterials and ...biomolecules in spatially predefined locations within confined three-dimensional (3D) structures. Various bioprinting technologies have been developed and utilized for applications in life sciences, ranging from studying cellular mechanisms to constructing tissues and organs for implantation, including heart valve, myocardial tissue, trachea and blood vessels. In this article, we introduce the general principles and limitations of the most widely used bioprinting technologies, including jetting- and extrusion-based systems. Application-based research focused on tissue regeneration is presented, as well as the current challenges that hamper clinical utility of bioprinting technology.
Three-dimensional printing enables precise and on-demand manufacture of customizable drug delivery systems to advance healthcare toward the goal of personalized medicine. However, major challenges ...remain in realizing personalized drug delivery that fits a patient-specific drug dosing schedule using local drug delivery systems. In this study, a user-designed device is developed as implantable therapeutics that can realize personalized drug release kinetics by programming the inner structural design on the microscale. The drug release kinetics required for various treatments, including dose-dense therapy and combination therapy, can be implemented by controlling the dosage and combination of drugs along with the rate, duration, initiation time, and time interval of drug release according to the device layer design. After implantation of the capsular device in mice, the in vitro–in vivo and pharmacokinetic evaluation of the device is performed, and the therapeutic effect of the developed device is achieved through the local release of doxorubicin. The developed user-designed device provides a novel platform for developing next-generation drug delivery systems for personalized and localized therapy.
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•A user-designed device is developed for personalized drug delivery that fits a patient-specific treatment schedule.•The device has programmable release kinetics of single or multiple drugs by controlling the internal structural design.•Drug release characteristics of the device show no difference between in vitro and in vivo environments.•The device exhibits high therapeutic efficiency in localized treatment.
Aqueous redox flow batteries (RFBs) have attracted significant attention as energy storage systems by virtue of their inexpensive nature and long‐lasting features. Although all‐vanadium RFBs exhibit ...long lifetimes, the cost of vanadium resources fluctuates considerably, and is generally expensive. Iron–chromium RFBs take advantage of utilizing a low‐cost and large abundance of iron and chromite ore; however, the redox chemistry of CrII/III generally involves strong Jahn–Teller effects. Herein, this work introduces a new Cr‐based negolyte coordinated with strong‐field ligands capable of mitigating strong Jahn–Teller effects, thereby facilitating low redox potential, high stability, and rapid kinetics. The balanced full‐cell configuration features a stable lifetime of 500 cycles with energy density of 14 Wh L−1. With an excessive posolyte, the full‐cell can attain a high energy density of 38.6 Wh L−1 as a single electron redox process. Consequently, the proposed system opens new avenues for the development of high‐performance RFBs.
A new iron‐chromium flow battery is discovered using hexacyanometallate compounds. This is the first demonstration of the use of hexacyanochromate ions to insulate flow batteries against the formidable challenges of parasitic hydrogen evolution reaction and cross‐contamination. The strong‐field ligand of cyanides plays a significant role in governing the low‐spin state of CrII, allowing for the low redox potential of negolytes.
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