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Carbon capture and liquefaction from methane steam reforming unit: 4E's analysis (Energy, Exergy, Economic, and Environmental)
No full textExcessive fossil-fuel consumption to meet increased energy demand is considered as the main reason of the climatic change. To prevent this devastating change, hydrogen has gained much attention as an intermediate to replace fossil-fuel-based energy systems by sustainable green energy system. Since most of the H-2 is produced through natural gas process, a trade-off in terms of huge amounts of CO2 emissions should be concerned. Accordingly, integration of the H-2 production and carbon capture facility actively, called blue H-2, emerges as a workable alternative. In addition, with the rise in CO2 demand, the liquefaction of captured CO2 has become an attractive strategy in terms of long-term storage and transportation. Therefore, a comprehensive study is performed to assess the feasibility of an integrated system based on carbon capture using monoethanol amine and four CO2 liquefaction systems such as Linde-Hampson, dual pressure Linde-Hampson, vapor compression refrigerant, and absorption refrigerant systems (later will use as case 1 to 4, respectively). Based on energy and exergy evaluations, case 4 reflects the higher efficiencies with specific energy consumption of 0.188(el) and 0.733th GJ ton CO2-1 and exergy efficiency of 85.55 %. In addition, techno-economic analysis calculates unit LCO2 production of each case; 22.19, 21.35, 21.00, and 24.60 $ ton(-1) for cases 1, 2, 3, and 4, respectively. The quantified climate change impacts were estimated by life-cycle assessment; 0.629, 0.620, 0.608. and 0.674 kg CO2-eq kg LCO2-1 for cases 1, 2, 3, and 4, respectively. Furthermore, analytic hierarchy process is performed to provide comprehensive guidelines of liquefied CO2 production under technical, economic, and environmental aspects
Operational Algorithm of Aerosol Effective Height from the Geostationary Environment Monitoring Spectrometer (GEMS)
No full textThe Geostationary Environment Monitoring Satellite (GEMS) retrieves several species of trace gases and aerosol properties. For the aerosol property, retrieval results from the GEMS can be used for the surface air quality analysis and aerosol effect for the airmass factor (AMF) calculation. To provide accurate information on aerosol, in addition, aerosol vertical information is also retrieved from the GEMS defined by the aerosol effective height (AEH). The AEH can help to estimate the AMF for tropospheric trace gases and surface concentration of particulate matter (PM).
The aerosol vertical distribution is relatively difficult to retrieve compared to those of clouds, because the optical property of aerosol is various due to the various aerosol types in the atmosphere. For the UV-visible hyperspectral observation, the aerosol vertical distribution can estimate from the absorption bands based on the Oxygen molecules, such as O2-A, O2-B, and O2-O2 absorption. Because of the limitation for the spectral coverage from 300~500 nm, however, GEMS is only available to use O2-O2 absorption bands. For the possibility of the AEH retrieval algorithm from GEMS, Park et al. (2016) investigated the theoretical sensitivity test of the AEH retrieval by solely using the O2-O2 absorption band with considering the aerosol and surface properties. Based on the previous studies, we introduce the operational retrieval algorithm for AEH with the theoretical basement. Also, we showed the performance of the operational AEH algorithm from GEMS based on case studies and the validation study using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)
Orai1-mediated store-operated Ca2+ entry (SOCE) in breast cancer signaling and entosis
No full textThe intracellular Ca2+ concentrations are highly regulated by a variety of Ca2+ channels that can be disrupted in cancer. Store-operated Ca2+ entry (SOCE) is a primary source of Ca2+ influx in non-excitable cells, which is activated by the decrease in Ca2+ concentration within the endoplasmic reticulum (ER) in response to cell surface receptor stimulation. SOCE is regulated by the ER membrane protein STIM1 (stromal interaction molecular 1), which translocates to the junctional sites between the ER and plasma membrane (PM) to open the Ca2+ channel Orai1 when sensing a decrease in ER Ca2+ concentration. Any disruption of STIM1 or Orai1 function can have a direct influence on SOCE and potentially affect various pathophysiological activities, such as cancer metastasis, which is accountable for approximately 90% of all cancer-related deaths.
Overexpression of progesterone receptor membrane component 1 (PGRMC1) is associated with decreased cancer patient survivability. However, the intracellular signaling pathways involved are largely unknown. Here, we report that PGRMC1 functions as a regulator of store-operated Ca2+ entry (SOCE) by interacting with stromal interaction molecular 1 (STIM1) to promote its conformational switch, leading to the activation of the nuclear factor of the activated T cell (NFAT) pathway. Additionally, genetic depletion of PGRMC1 caused impaired SOCE and disrupted focal adhesion turnover and actomyosin formation in breast cancer cells. These findings indicate that PGRMC1 is essential for regulating Ca2+ signaling in breast cancer cells, providing a potential target for treating cancer metastasis and a greater understanding of the PGRMC1/SOCE-induced biological processes.
Additionally, entosis is a non-apoptotic process of cell death that forms characteristic cell-in-cell structures and induces cancer development. The role of Ca2+ and Ca2+ channels in the process of entosis is not well understood. Here, we demonstrate that Orai1 is an entotic Ca2+ channel and provokes Ca2+ oscillations, which play a role in the engulfment of entotic cells. Furthermore, we show that SEPTIN-Orai1-Ca2+/CaM-MLCK-actomyosin axis is a mechanism by which Orai1 regulates entosis, potentially leading to cancer development
Electrical addressing of exceptional points in compact plasmonic structures
No full textExceptional points (EPs) are degenerate singularities in a non-Hermitian system that can be induced by controlling the interaction between resonant photonic modes. EPs can enable unusual optical phenomena and significantly enhance the optical sensitivity under small perturbations. However, most studies thus far have been limited to static photonic structures. In this study, we propose and experimentally demonstrate electrically addressable EP in a plasmonic structure. Inspired by optical microcavity studies, we employ a localized spoof plasmon structure that supports circulating plasmonic modes in compact single-resonator geometry. The plasmonic modes are perturbed by an angled metal line, and the interaction between the plasmonic modes is electrically controlled using a varactor. Continuous electrical tuning of the varactor capacitance facilitates simultaneous coalescence of the real and imaginary parts of the eigenfrequency, allowing the direct addressing of EPs. We first investigate the eigenmodes and their coupling in localized plasmonic structures using numerical simulations. We then present experimentally measured spectra that manifest the coalescence of the two resonant modes in both the resonance frequency and linewidth. Electrically addressable EPs in compact plasmonic structures may provide exciting opportunities for highly functional and tunable elements in integrated device platforms
Reconfigurable Low-Voltage Hexagonal Boron Nitride Nonvolatile Switches for Millimeter-Wave Wireless Communications
No full textRecently, nonvolatile resistive switching memory effects have been actively studied in two-dimensional (2D) transition metal dichalcogenides and boron nitrides to advance future memory and neuromorphic computing applications. Here, we report on radiofrequency (RF) switches utilizing hexagonal boron nitride (hBN) memristors that afford operation in the millimeter-wave (mmWave) range. Notably, silver (Ag) electrodes to h-BN offer outstanding nonvolatile bipolar resistive switching characteristics with a high ON/OFF switching ratio of 1011 and low switching voltage below 0.34 V. In addition, the switch exhibits a low insertion loss of 0.50 dB and high isolation of 23 dB across the D-band spectrum (110 to 170 GHz). Furthermore, the S21 insertion loss can be tuned through five orders of current compliance magnitude, which increases the application prospects for atomic switches. These results can enable the switch to become a key component for future reconfigurable wireless and 6G communication systems
