Showing papers by "National Tsing Hua University published in 2022"

New‐onset autoimmune phenomena post‐COVID‐19 vaccination

Abstract: Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to an unprecedented setback for global economy and health. Vaccination is one of the most effective interventions to substantially reduce severe disease and death due to SARS-CoV-2 infection. Vaccination programmes are being rolled out globally, but most of these vaccines have been approved without extensive studies on their side-effects and efficacy. Recently, new-onset autoimmune phenomena after COVID-19 vaccination have been reported increasingly (e.g. immune thrombotic thrombocytopenia, autoimmune liver diseases, Guillain-Barré syndrome, IgA nephropathy, rheumatoid arthritis and systemic lupus erythematosus). Molecular mimicry, the production of particular autoantibodies and the role of certain vaccine adjuvants seem to be substantial contributors to autoimmune phenomena. However, whether the association between COVID-19 vaccine and autoimmune manifestations is coincidental or causal remains to be elucidated. Here, we summarize the emerging evidence about autoimmune manifestations occurring in response to certain COVID-19 vaccines. Although information pertaining to the risk of autoimmune disease as a consequence of vaccination is controversial, we merely propose our current understanding of autoimmune manifestations associated with COVID-19 vaccine. In fact, we do not aim to disavow the overwhelming benefits of mass COVID-19 vaccination in preventing COVID-19 morbidity and mortality. These reports could help guide clinical assessment and management of autoimmune manifestations after COVID-19 vaccination.

Chiral Diene Ligands in Asymmetric Catalysis

Abstract: Asymmetric catalysis has emerged as a general and powerful approach for constructing chiral compounds in an enantioselective manner. Hence, developing novel chiral ligands and catalysts that can effectively induce asymmetry in reactions is crucial in modern chemical synthesis. Among such chiral ligands and catalysts, chiral dienes and their metal complexes have received increased attention, and a great progress has been made over the past two decades. This review provides comprehensive and critical information on the essential aspects of chiral diene ligands and their importance in asymmetric catalysis. The literature covered ranges from August 2003 (when the first effective chiral diene ligand for asymmetric catalysis was reported) to October 2021. This review is divided into two parts. In the first part, the chiral diene ligands are categorized according to their structures, and their preparation methods are summarized. In the second part, their applications in asymmetric transformations are presented according to the reaction types.

In-situ grown metal-organic framework-derived carbon-coated Fe-doped cobalt oxide nanocomposite on fluorine-doped tin oxide glass for acidic oxygen evolution reaction

Abstract: Development of stable and efficient non-noble metal based electrocatalysts for oxygen evolution reaction (OER) in acidic media is of great importance for proton exchange membrane based water electrolysis, which is indispensable for green hydrogen production. Herein, iron-doped, carbon-coated Co3O4 nanocomposite derived from a cobalt metal-organic framework, is grown in-situ on fluorine-doped tin oxide (FTO) glass (Fe-Co3O4@C/FTO) as an efficient and a stable binder-free electrode for acidic OER. Fe doping enhances both catalytic efficiency and stability of carbon coated Co3O4 toward acidic OER, through inducing small primary particle sizes and suitably modulated electronic structure of Co3O4, and better catalyst/substrate adhesion. Fe-Co3O4@C/FTO exhibits impressive electrocatalytic performances in 0.5 M H2SO4, with a low overpotential of 396 mV at 10 mA cm−2 and a small Tafel slope of 68.6 mV dec−1. Its electrochemical performances remain stable for over 50 h at 10 mA cm−2, making it a promising non-noble metal based electrocatalyst for acidic OER.

The role of lattice dynamics in ferroelectric switching

Abstract: Reducing the switching energy of ferroelectric thin films remains an important goal in the pursuit of ultralow-power ferroelectric memory and logic devices. Here, we elucidate the fundamental role of lattice dynamics in ferroelectric switching by studying both freestanding bismuth ferrite (BiFeO3) membranes and films clamped to a substrate. We observe a distinct evolution of the ferroelectric domain pattern, from striped, 71° ferroelastic domains (spacing of ~100 nm) in clamped BiFeO3 films, to large (10's of micrometers) 180° domains in freestanding films. By removing the constraints imposed by mechanical clamping from the substrate, we can realize a ~40% reduction of the switching voltage and a consequent ~60% improvement in the switching speed. Our findings highlight the importance of a dynamic clamping process occurring during switching, which impacts strain, ferroelectric, and ferrodistortive order parameters and plays a critical role in setting the energetics and dynamics of ferroelectric switching.

Fabrication of visible-light-driven tubular F, P-codoped graphitic carbon nitride for enhanced photocatalytic degradation of tetracycline

Abstract: The fluorine and phosphorus co-doped tubular g-C3N4 (CNPF) photocatalyst has been successfully synthesized through hydrothermally supramolecular self-assembly at 180 ºC for 10 h followed by the crystallization at 500 ºC for 4 h in N2. The as-prepared CNPF was then used for the photocatalytic degradation of tetracycline (TC) under visible-light irradiation at 460 nm. Tubular CNPF structures can shorten the diffusion length thereby increasing the electric conductivity and electron transfer rate. The P element can replace C atoms in g-C3N4 to delocalize the π-conjugated triazine structure. Moreover, addition of F atoms significantly reduces the bandgap and recombination rate of holes and electrons, leading to the enhanced photocatalytic degradation of TC under different environmental conditions. The as-prepared CNPF exhibits TC photodegradation rate 4.2–11.7 times higher than that of pristine g-C3N4 under different environmental conditions. CNPF also shows significant stability and reusability with 98% of mineralization efficiency in 5 cycles. Results of radical trapping experiments clearly indicate that hole and superoxide radical are the dominant reactive species enhancing TC photodegradation. Moreover, the possible reaction mechanism for TC photodegradation over CNPF are proposed.

Phenanthroimidazole substituted imidazo[1,2-a]pyridine derivatives for deep-blue electroluminescence with CIEy ∼ 0.08

Abstract: Blue emitting materials with balanced charge carrying capacity are crucial for effective OLED. Phenanthroimidazole based deep blue materials are developed with a donor-acceptor configuration to optimize charge balance in OLEDs. In this work, three new dipolar materials based on the phenanthroimidazole-imidazopyridine conjugated system were synthesized and characterized. The position and number of phenanthroimidazole substituents are changed to study structure property relationships. All derivatives carried superb thermal stability and high photoluminescence quantum yield. Dyes in which phenanthroimidazole chromophore linked at the para-position of C2 phenyl ring showed the red-shifted emission band. The positive solvatochromism was observed with the increase of solvent polarity, associated with the intramolecular charge transfer at excited state. The electrochemical measurement revealed that the fluorophores have low-lying LUMO energy levels. Further, doped devices were fabricated with these emitters to estimate the EL performances. Among all the emitters, the doped device fabricated with a dye containing phenanthroimidazole chromophore at para-position of C2 phenyl showed superior electroluminescence performance with CIE coordinates (0.16, 0.08).

Artificial Intelligence-Based Real-Time Pineapple Quality Classification Using Acoustic Spectroscopy

Abstract: The pineapple is an essential fruit in Taiwan. Farmers separate pineapples into two types, according to the percentages of water in the pineapples. One is the “drum sound pineapple” and the other is the “meat sound pineapple”. As there is more water in the meat sound pineapple, the meat sound pineapple more easily rots and is more challenging to store than the drum sound pineapple. Thus, farmers need to filter out the meat sound pineapple, so that they can sell pineapples overseas. The classification, based on striking the pineapple fruit with rigid objects (e.g., plastic rulers) is most commonly used by farmers due to the negligibly low costs and availability. However, it is a time-consuming job, so we propose a method to automatically classify pineapples in this work. Using embedded onboard computing processors, servo, and an ultrasonic sensor, we built a hitting machine and combined it with a conveyor to automatically separate pineapples. To classify pineapples, we proposed a method related to acoustic spectrogram spectroscopy, which uses acoustic data to generate spectrograms. In the acoustic data collection step, we used the hitting machine mentioned before and collected many groups of data with different factors; some groups also included the noise in the farm. With these differences, we tested our deep learning-based convolutional neural network (CNN) performances. The best accuracy of the developed CNN model is 0.97 for data Group V. The proposed hitting machine and the CNN model can assist in the classification of pineapple fruits with high accuracy and time efficiency.

Effects of Subseasonal Variation in the East Asian Monsoon System on the Summertime Heat Wave in Western North America in 2021

Abstract: In the early summer (late June–early July) of 2021, a prolonged and extremely high temperature event was observed in the Northwest United States and Southwest Canada. In this study, a connection was found between the subseasonal variations of the East Asian monsoon system and the anomalous heat dome over western North America (WNA). Around 2–3 pentads prior to the period of maximum heat, a northward-propagating rain belt and abnormally intensified jet stream in East Asia excited a Rossby wave train, causing the high-pressure anomaly over WNA that was responsible for the occurrence of this heat wave in 2021. Multivariate singular value decomposition analysis results using historical data and a series of numerical experiments further supported the finding of this East Asia–western North America teleconnection. The results provide precursor signals for better monitoring and predicting heat waves over WNA.

Cosmological Constraints on Nonflat Exponential f(R) Gravity

Abstract: We explore the viable $f(R)$ gravity models in FLRW backgrounds with a free spatial curvature parameter $\Omega_{K}$. In our numerical calculation, we concentrate on the exponential $f(R)$ model of $f(R) = R - \lambda R_{ch}(1-\exp{(-R/R_{ch}}))$, where $R_{ch}$ is the characteristic curvature scale, which is independent of $\Omega_K$, and $\lambda$ corresponds to the model parameter, while $R_{ch}\lambda=2\Lambda$ with $\Lambda$ the cosmological constant. In particular, we study the evolutions of the dark energy density and equation of state for exponential $f(R)$ gravity in open, flat and closed universe, and compare with those for $\Lambda$CDM. From the current observational data, we find that $\lambda^{-1}=0.42927^{+0.39921}_{-0.32927}$ at 68$\%$ C.L and $\Omega_K=-0.00050^{+0.00420}_{-0.00414}$ at 95$\%$ C.L. in the exponential $f(R)$ model. By using Akaike information criterion (AIC), Bayesian information criterion (BIC) and Deviance Information Criterion (DIC), we conclude that there is no strong preference between the exponential $f(R)$ gravity and $\Lambda$CDM models in the non-flat universe.