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A Rectifier-Reusing Bias-Flip Energy Harvesting Interface Circuit With Adaptively Reconfigurable SC Converter for Wind-Driven Triboelectric Nanogenerator
No full textThe energy harvesting interface circuit is proposed for wind-driven triboelectric nanogenerator (WDTENG). To extract power from the WD-TENG maximally and deliver power to the output (battery) efficiently, a rectifierreusing bias-flip (RRBF) technique and a multiphase reconfigurable switched-capacitor converter (MRSCC) are developed. In the RRBF, the low-side switches of the rectifier are reused as switches for bias-flip without additional components. The MRSCC delivers power to the battery efficiently by reducing switching loss including overlap loss. Furthermore, the MRSCC maintains a rectified voltage (V RECT) as high as a breakdown voltage (V BR) of a switch by adaptive conversion control and multiphase operation to extract maximized power from the WD-TENG in a given process, even if the battery voltage is varied from 2.7 to 4.2 V. Owing to the proposed techniques, the maximum extracted power to the output is 238 mu W and peak power delivering efficiency of the MRSCC is 79.3%. The chip was fabricated in 0.18 mu m BCD process
Probing the Melting Transitions in Phase-Change Superlattices via Thin Film Nanocalorimetry
No full textPhase-change superlattices with nanometer thin sublayers are promising for low-power phase-change memory (PCM) on rigid and flexible platforms. However, the thermodynamics of the phase transition in such nanoscale superlattices remain unexplored, especially at ultrafast scanning rates, which is crucial for our fundamental understanding of superlattice-based PCM. Here, we probe the phase transition of Sb2Te3 (ST)/Ge2Sb2Te5 (GST) superlattices using nanocalorimetry with a monolayer sensitivity (similar to 1 angstrom) and a fast scanning rate (10(5) K/s). For a 2/1.8 nm/nm Sb2Te3/GST superlattice, we observe an endothermic melting transition with an similar to 240 degrees C decrease in temperature and an similar to 8-fold decrease in enthalpy compared to those for the melting of GST, providing key thermodynamic insights into the low-power switching of superlattice-based PCM. Nanocalorimetry measurements for Sb2Te3 alone demonstrate an intrinsic premelting similar to the unique phase transition of superlattices, thus revealing a critical role of the Sb2Te3 sublayer within our superlattices. These results advance our understanding of superlattices for energy-efficient data storage and computing
Coupling nitrate capture with ammonia production through bifunctional redox-electrodes
No full textNitrate is a ubiquitous aqueous pollutant from agricultural and industrial activities. At the same time, conversion of nitrate to ammonia provides an attractive solution for the coupled environmental and energy challenge underlying the nitrogen cycle, by valorizing a pollutant to a carbon-free energy carrier and essential chemical feedstock. Mass transport limitations are a key obstacle to the efficient conversion of nitrate to ammonia from water streams, due to the dilute concentration of nitrate. Here, we develop bifunctional electrodes that couple a nitrate-selective redox-electrosorbent (polyaniline) with an electrocatalyst (cobalt oxide) for nitrate to ammonium conversion. We demonstrate the synergistic reactive separation of nitrate through solely electrochemical control. Electrochemically-reversible nitrate uptake greater than 70 mg/g can be achieved, with electronic structure calculations and spectroscopic measurements providing insight into the underlying role of hydrogen bonding for nitrate selectivity. Using agricultural tile drainage water containing dilute nitrate (0.27 mM), we demonstrate that the bifunctional electrode can achieve a 8-fold up-concentration of nitrate, a 24-fold enhancement of ammonium production rate (108.1 ug h???1 cm???2), and a >10-fold enhancement in energy efficiency when compared to direct electrocatalysis in the dilute stream. Our study provides a generalized strategy for a fully electrified reaction-separation pathway for modular nitrate remediation and ammonia production
Commissioning results of single bunch selection system for the RAON heavy-ion accelerator facility
No full textTo enable neutron time-of-flight experiments at the RAON heavy-ion accelerator facility, we tested a single bunch beam selection method by combining an RF chopper and a double gap buncher in the low-energy beam transport section. The RF chopper converts a CW beam into a hundreds-nanosecond pulsed beam. Then, the double gap buncher performs bunching to shorten the pulse length to less than one radio frequency quadrupole (RFQ) cycle. Ideally, a single isolated bunch can be achieved after the RFQ. In this study, we discuss the design concept of the single bunch selection system and present initial beam commissioning results
Manipulating Physicochemical Properties of Biosensor Platform with Polysuccinimide-Silica Nanocomposite for Enhanced Protein Detection
No full textAs point-of-care testing (POCT) is becoming the new paradigm of medical diagnostics, there is a growing need to develop reliable POCT devices that can be conveniently operated in a minimally invasive manner. However, the clinical potential of POCT diagnostics is yet to be realized, mainly due to the limited and inconsistent amount of collected samples on these devices, undermining their accuracy. This study proposes a new biosensing platform modified with a functional polysuccinimide (PSI)-silica nanoparticle (SNP) composite system that can substantially increase the protein conjugation efficiency by modulating physicochemical interaction with proteins by several hundred percent from an unmodified device. The efficacy of this PSI-SNP system is further validated by applying it on the surface of a microneedle array (MN), which has emerged as a promising POCT device capable of accessing interstitial fluid through minimal penetration of the skin. This PSI-SNP MN is demonstrated to detect a wide array of proteins with high sensitivity on par with conventional whole serum analysis, validated by in vivo animal testing, effectively displaying broad applicability in biomedical engineering
Atomic Layer Deposition Route to Scalable, Electronic-Grade van der Waals Te Thin Films
No full textScalable production and integration techniques for vander Waals(vdW) layered materials are vital for their implementation in next-generationnanoelectronics. Among available approaches, perhaps the most well-receivedis atomic layer deposition (ALD) due to its self-limiting layer-by-layergrowth mode. However, ALD-grown vdW materials generally require highprocessing temperatures and/or additional postdeposition annealingsteps for crystallization. Also, the collection of ALD-produciblevdW materials is rather limited by the lack of a material-specifictailored process design. Here, we report the annealing-free wafer-scalegrowth of monoelemental vdW tellurium (Te) thin films using a rationallydesigned ALD process at temperatures as low as 50 & DEG;C. They exhibitexceptional homogeneity/crystallinity, precise layer controllability,and 100% step coverage, all of which are enabled by introducing adual-function co-reactant and adopting a so-called repeating dosingtechnique. Electronically, vdW-coupled and mixed-dimensional verticalp-n heterojunctions with MoS2 and n-Si, respectively, aredemonstrated with well-defined current rectification as well as spatialuniformity. Additionally, we showcase an ALD-Te-based threshold switchingselector with fast switching time (& SIM;40 ns), selectivity (& SIM;10(4)), and low V (th) (& SIM;1.3 V).This synthetic strategy allows the low-thermal-budget production ofvdW semiconducting materials in a scalable fashion, thereby providinga promising approach for monolithic integration into arbitrary 3Ddevice architectures
Feasibility study of power-to-gas as simultaneous renewable energy storage and CO2 utilization: Direction toward economic viability of synthetic methane production
No full textAccording to an increase in concerns for environmental issues, the energy transition toward sustainable and alternative energy has received much attention. Synthetic methane, which is a fuel synthesized by the reaction of green hydrogen (H2) and carbon dioxide (CO2), is perceived as a promising alternative to fossil-fuel-based natural gas. A feasibility study of synthetic methane production focusing on green H2 production is conducted to investigate how to make the technology economically feasible. Cost estimation for methane production is performed by classifying various scenarios of H2 production based on water electrolysis technologies and renewable energy resources. The production costs of synthetic methane show diverse ranges following the considerations: 0.049-0.199, 0.059-0.215, and 0.154-0.273 $ kWh-1 for alkaline water electrolysis, polymer electrolyte membrane water electrolysis, and solid oxide water electrolysis, respectively. Moreover, sensitivity analysis discloses that parameters associated with green H2 production costs dominate the methane costs; therefore, predictive analysis demonstrates the economic outlook of synthetic methane production by applying learning-by-doing effects, future performance of electrolyzer, and renewable electricity costs. Consequently, we reveal the possibility of onshore wind electricity that can achieve economic feasibility with fully developed electrolysis systems for green H2 production at low electricity prices
Highly Efficient and Stable Green Phosphorescent Light-Emitting Diodes Based on Solution-Processable Ir(III) Complexes with Electron-Transporting Ancillary Ligands
No full textTwo green heteroleptic Ir(III) complexes are reported, namely, bis[5-(2-ethylhexyl)-8-trifluoromethyl-5H-benzo[c][1,5]-naphthyridin-6-one](2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenolate)iridium (III) (Ir(CF3BNO)(2)-pop) and bis[5-(2-ethylhexyl)-5H-benzo[c][1,5]naphthyridin-6-one](2-(5-phenyl-1,3,4-oxadiazol-2-yl)phenolate)iridium (III) (Ir(BNO)(2)-pop) for solution-processed phosphorescent organic light-emitting diodes (PHOLEDs). Both the Ir(III) complexes exhibit high external quantum efficiency (EQE) and intense green emission upon using poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) as a hole injection layer (HIL); Ir(CF3BNO)(2)-pop based PHOLEDs perform better with an EQE of 23% and a current efficiency of 82 cd A(-1) than Ir(BNO)(2)-pop based PHOLEDs. In addition, to improve device operational lifetime, a crosslinkable HIL material, 9,9'-(cyclohexane-1,1-diylbis(4,1-phenylene))bis(N-phenyl-N-(4-(((4-vinylbenzyl)oxy)methyl)phenyl)-9H-carbazol-3-amine) (CPCzDPAX-1) is designed and synthesized. Device operational lifetimes of Ir(CF3BNO)(2)-pop and Ir(BNO)(2)-pop PHOLEDs incorporating the CPCzDPAX-1 HIL show 14-fold and 6-fold improvement, compared to the corresponding devices incorporating the PEDOT:PSS HIL. To the best of the authors' knowledge, this is the best device lifetime performance by using the combination of new Ir(III) complexes and HIL materials for solution-processed green PHOLEDs
Modulation of Macrophages by In Situ Ligand Bridging
No full textExtracellular matrix (ECM) proteins containing cell-attachable Arg-Gly-Asp (RGD) sequences exhibit variable bridging and non-bridging in fibronectin-collagen and laminin-collagen complexes that can regulate inflammation, tissue repair, and wound healing. In this study, linking molecule-mediated conjugation of 1D magnetic nanocylinders (MNCs) to material surfaces pre-decorated with gold nanospheres (GNSs) is performed, thereby yielding RGD-coated MNCs (RGD-MNCs) over RGD-coated GNSs (RGD-GNSs) in a non-bridging state. The RGD-MNCs are drawn closer to the RGD-GNSs via magnetic field-mediated compression of the linking molecules to establish the bridging between them. Relative proportion of the RGD-MNCs to the RGD-GNSs is optimized to yield effective remote stimulation of integrin binding to variably bridged RGDs similar to that of invariably bridged RGDs used as a control group. Remote manipulation of the RGD bridging facilitates the attachment structure assembly of macrophages that leads to pro-healing/anti-inflammatory phenotype acquisition. In contrast, the non-bridged RGDs inhibited macrophage attachment that acquired pro-inflammatory phenotypes. The use of various nanomaterials in constructing heterogeneous RGD-coated materials can further offer various modes in remote switching of RGD bridging and non-bridging to understand dynamic integrin-mediated modulation of macrophages that regulate immunomodulatory responses, such as foreign body responses, tissue repair, and wound healing