National Tsing Hua University
Recent publications
Contagious pathogens, such as influenza and COVID-19, are known to be represented by multiple genetic strains. Different genetic strains may have different characteristics, such as spreading more easily, causing more severe diseases, or even evading the immune response of the host. These facts complicate our ability to combat these diseases. There are many ways to prevent the spread of infectious diseases, and vaccination is the most effective. Thus, studying the impact of vaccines on the dynamics of a multi-strain model is crucial. Moreover, the notion of complex networks is commonly used to describe the social contacts that should be of particular concern in epidemic dynamics. In this paper, we investigate a two-strain epidemic model using a single-strain vaccine in complex networks. We first derive two threshold quantities, R1 and R2, for each strain. Then, by using the basic tools for stability analysis in dynamical systems (i.e., Lyapunov function method and LaSalle’s invariance principle), we prove that if R1<1 and R2<1, then the disease-free equilibrium is globally asymptotically stable in the two-strain model. This means that the disease will die out. Furthermore, the global stability of each strain dominance equilibrium is established by introducing further critical values. Under these stability conditions, we can determine which strain will survive. Particularly, we find that the two strains can coexist under certain condition; thus, a coexistence equilibrium exists. Moreover, as long as the equilibrium exists, it is globally stable. Numerical simulations are conducted to validate the theoretical results.
Novel detached curved ribs are proposed in this study and their influence on turbulent thermofluidic features in a two-pass U-shaped square channel is experimentally investigated using particle image ve-locimetry (PIV) and infrared thermography (IRT). Due to their geometric complexity, the ribs are fabricated with the 3D printing technology-fused deposition modeling and mounted in line inside the channel with a hydraulic diameter (D H) of 45.5 mm. Examined parameters include the rib convergence angle (α), divergence angle (β), clearance ratio (C / H), and Reynolds number, which are respectively in the range of (25 °, 35 °, 45 °), (30 °, 40 °, 50 °), (0.25, 0.38, 0.56, 0.75, and 1), and (5,0 0 0-20,0 0 0). The PIV and IRT results show that that the detached curved ribs accelerate the core flow and significantly strengthen the Dean vortices in the turn region, leading up to 70% enhancement in Nusselt number ratio (Nu /Nu ∞) in that region compared with previous best results. Further parametric studies reveal that at α= 25 ˚and β = 40 °, Nu /Nu ∞ and Fanning friction factor ratio (f / f ∞) first increase and then decrease with increasing C / H , with the maximum thermal performance factor (TPF) of 1.4 occurring at C / H = 0.38, slightly higher than the previous highest data for f / f ∞ = 10-50. Finally, empirical formulations of Nu /Nu ∞ and f / f ∞ with α, β, C/H, and Re for the present design are proposed with an average difference of 2.24% and 4.95%, respectively.
Beyond 5G (B5G) in mobile network technologies is the latest communication technology currently under development. B5G is expected to achieve superior capabilities in ultra-high network transmission speed, low latency, low energy consumption, and high coverage, comparing to current 5G network performance. Although B5G is still in the development and implementation stage, there are many patents and non-patent literature depicting B5G innovative technologies and applications. The landscapes of B5G technologies are great references for governments and industries to understand the advances in mobile communication for R&D strategies. Thus, this research focuses on developing a formal tech-mining workflow integrating semantic-based patent and non-patent literature analysis for ontology building, patent technological topic clustering, and graph convolutional network (GCN) modeling for depicting key technology interactions among clusters of sub-domain topics. This research emphasizes the study of B5G patent landscape and key technology interaction roadmap in comprehensive steps as a valuable reference for B5G mobile network R&D, as well as for conducting tech-mining of other technology domains of interests.
The increasing generation of solid waste, varying waste compositions, and inefficient waste recovery processes have limited the performance of traditional approaches. It is urgent to collect a virtual special issue (VSI) that consolidates research on efficient models and better treatment technologies to break up the current system limitations. Recently, Solid Waste Management (SWM) strategies that focus on reuse and recycling have revealed their current limitations or challenges. An awareness of the progress in addressing these limitations through the advancement in available technologies and the development of new systematic approaches for SWM are of increasing importance not just for advanced but more for emerging economies. Herein, this VSI aims to provide a review and collect important studies for SWM on reuse and recycling. The challenges and future opportunities in the application of SWM have been discussed to highlight the potential development in this VSI.
The diffusion and segregation rates of immiscible alloying elements in Cu-based alloys with one (V) or five refractory metals (V, Nb, Mo, Ta and W) at 300 to 500 °C were investigated for understanding the kinetics of phase separation in multicomponent alloys. At a comparable grain size and a similar influence of grain boundary diffusion (more dominant at 300 °C), the summed rate constant of segregation of the five alloying elements was higher than that of the one element, attributable to the larger entropy change for vacancy formation and atom exchange. The rate constant and time exponent of segregation depended on the melting temperature of the alloying element (W > Ta > Mo > Nb > V), while the activation energy of diffusion, 5.1 to 12.3 kJ/mole (W < Mo < V < Nb < Ta), was inversely related to the delta mixing enthalpy (to Cu) or electronegativity.
Transparent conductive oxides (TCOs) are indispensable as transparent electrodes in optoelectronic applications due to their unique features of high optical transmittance, high electrical conductivity, and cost-effective industrial-scale manufacturability. However, patterning TCO films for functional devices requires lengthy and expensive photolithography and etching processes. Although the laser patterning technique—based on nanoparticle ink and particle-free ink—has been used to fabricate patterned metal electrodes without photolithography, it is still unknown if it works for TCO, such as doped zinc oxide (ZnO). Here, we introduce a novel single-step maskless, particle-free, and ink-free process to deposit transparent, conductive Ga-doped ZnO (GZO) patterns on glass substrates via a laser-assisted atmospheric pressure plasma jet (APPJ) technique. With the exposure of a plasma jet, GZO patterns can be deposited by scanning a continuous-wave CO2 laser using a galvanometer and computer-aided design (CAD) images. The GZO patterns (∼100 nm thick) are visually transparent and exhibit remarkably low resistivity of 7.89 × 10–4 Ω cm, comparable with that of uniform (unpatterned) GZO films prepared by APPJ only. Our present work fundamentally differs from prior works since neither particles nor ink is applied to the substrate before processing. The entire process is conducted in ambient conditions without substrate preheating and pre-/post-processing. Also, it does not require expensive vacuum apparatus and pulsed laser sources and has a high potential for cost-effective and sustainable fabrication of TCO patterns and circuits.
A thermomagnetic pump represents a novel pumping system that can be operated by simply heating and applying an external magnetic field. The working fluid in the thermomagnetic pump is temperature-sensitive magnetic fluid (TSMF). The magnetization of the TSMF decreases as its temperature increases. In the present study, a set of sub-millimeter thermomagnetic pumps was fabricated in microchannel systems with channel heights of 180, 290, 350, and 420 μm. A microheater was placed underneath the microchannel to control the input heat flux. A flow meter and five thermocouples were installed to examine the performance of these thermomagnetic pumps under different heating conditions. Although the flow rate increases as the height of the microchannel rise, the highest flow rate of 81.74 μl/min was achieved under the highest heating condition of 459.8 kW/m² and channel height of 350 μm, instead of 420 μm, due to the high Prandtl number of the TSMF.
In our previous study, we have shown that a heat pipe heat exchanger system modified from a commercial air-to-air heat exchanger operates without pulsations for working fluids of dielectric HFE-7000 or R134a, or under low heat loads for water, due to the large internal tube diameter of 5.6 mm. To incite pulsation and enhance the thermal performance, a straight dividing copper board is inserted into the straight section of each of the tube to form two semicircular compartments with an effective hydraulic diameter of 3.4 mm. The heat transfer characteristics and thermal performance against the hot air inlet temperature for the novel boarded model and the non-boarded model are experimentally explored with three working fluids (water, HFE-7000 and R134a) under six filling ratios (35%, 38.5%, 50%, 55%, 65%, 71.5%). Because water already works in a PHP mode in the non-boarded model under high heat loads, the thermal performance in the boarded model improved mildly by 2.7%–10.6%. Whereas, for HFE-7000 and R134a, the heat transfer mode is successfully incited from thermosyphon in the non-boarded model into PHP in the boarded model. The most significant thermal performance improvement was observed for HFE-7000 by 8.3%–24.5%. The improvement can be attributed to the switch of heat transfer mode, the generated corners for condensate accumulation, and the additional heat conduction via the copper board.
Identifying multitarget impurities on contact lenses is challenging because traditional methods such as polymerase chain reaction cannot be used on the unknown target. Other sampling methods often require expensive antibodies or dyes. Therefore, this research focuses on the detection of multitarget impurities in situ on the lens surface as a more innovative and effective label-free assay using scanning electrochemical microscopy (SECM). Impurities were investigated using an electrochemical assay and an oxygen consumption assay. The electrochemical activity of BSA and the bacteria adhered to the contact lenses was explored using a FcMeOH solution. The experimental results revealed the difference in current values of the clean and protein-adsorbed contact lens samples. Furthermore, SECM can be used to detect the oxygen consumption of aerobic microbes using the oxygen reduction method. Thus, contaminated microbes can be identified without labeling in phosphate buffer saline. The mass spectra of the contact lenses were studied and the adsorption of impurities was verified. Finally, contact lens samples were investigated from various patients with ocular infection diagnosed with corneal ulcers, preseptal cellulitis, and orbital cellulitis. As a result, SECM could be a new tool for distinguishing the cleanliness of contact lenses in the future.
The complex process of wound healing depends on the coordinated interaction between various immunological and biological systems, which can be aided by technology. This present review provides a broad overview of the medical applications of piezoelectric and triboelectric nanogenerators, focusing on their role in the development of wound healing technology. Based on the finding that the damaged epithelial layer of the wound generates an endogenous bioelectric field to regulate the wound healing process, development of technological device for providing an exogenous electric field has therefore been paid attention. Authors of this review focus on the design and application of piezoelectric and triboelectric materials to manufacture self-powered nanogenerators, and conclude with an outlook on the current challenges and future potential in meeting medical needs and commercialization.
Lipid droplets (LDs) are organelles that function as sites for lipid storage. LDs have also been implicated in the cellular response to proteotoxic or lipotoxic stress as sites for sequestering dysfunctional or excess proteins or lipids, and targeting those cargos for degradation by LD microautophagy (microlipophagy, µLP). Here, we describe two mechanisms for µLP in yeast, which are triggered by different stressors. µLP occurs at raft-like liquid ordered microdomains in the vacuolar membrane in yeast exposed to severe nutrient limitations. In contrast, in yeast exposed to ER stress or less severe nutrient limitations, LD uptake at the vacuole is liquid ordered (Lo) microdomain-independent and dependent upon vacuolar membrane remodeling mediated by endosomal sorting complexes required for transport (ESCRT).
An on-wafer micro-detector for in situ EUV (wavelength of 13.5 nm) detection featuring FinFET CMOS compatibility, 1 T pixel and battery-less sensing is demonstrated. Moreover, the detection results can be written in the in-pixel storage node for days, enabling off-line and non-destructive reading. The high spatial resolution micro-detectors can be used to extract the actual parameters of the incident EUV on wafers, including light intensity, exposure time and energy, key to optimization of lithographic processes in 5 nm FinFET technology and beyond.
Rice blast, one of the most destructive epidemic diseases, annually causes severe losses in grain yield worldwide. To manage blast disease, breeding resistant varieties is considered a more economic and environment-friendly strategy than chemical control. For breeding new resistant varieties, natural germplasms with broad-spectrum resistance are valuable resistant donors, but the number is limited. Therefore, artificially induced mutants are an important resource for identifying new broad-spectrum resistant ( R ) genes/loci. To pursue this approach, we focused on a broad-spectrum blast resistant rice mutant line SA0169, which was previously selected from a sodium azide induced mutation pool of TNG67, an elite japonica variety. We found that SA0169 was completely resistant against the 187 recently collected blast isolates and displayed durable resistance for almost 20 years. Linkage mapping and QTL-seq analysis indicated that a 1.16-Mb region on chromosome 6 ( Pi169-6 ( t )) and a 2.37-Mb region on chromosome 11 ( Pi169-11 ( t )) conferred the blast resistance in SA0169. Sequence analysis and genomic editing study revealed 2 and 7 candidate R genes in Pi169-6 ( t ) and Pi169-11 ( t ), respectively. With the assistance of mapping results, six blast and bacterial blight double resistant lines, which carried Pi169-6 ( t ) and/or Pi169-11 ( t ), were established. The complementation of Pi169-6 ( t ) and Pi169-11 ( t ), like SA0169, showed complete resistance to all tested isolates, suggesting that the combined effects of these two genomic regions largely confer the broad-spectrum resistance of SA0169. The sodium azide induced mutant SA0169 showed broad-spectrum and durable blast resistance. The broad resistance spectrum of SA0169 is contributed by the combined effects of two R regions, Pi169-6 ( t ) and Pi169-11 ( t ). Our study increases the understanding of the genetic basis of the broad-spectrum blast resistance induced by sodium azide mutagenesis, and lays a foundation for breeding new rice varieties with durable resistance against the blast pathogen.
DNA-templated metallization is broadly investigated in the fabrication of metallic structures by virtue of the unique DNA-metal ion interaction. However, current DNA-templated synthesis is primarily carried out based on pure DNA in an aqueous solution. In this study, we present in situ synthesis of metallic structures in a natural DNA complex bulk film by UV light irradiation, where the growth of silver particles is resolved by in situ time-resolved small-angle X-ray scattering and dielectric spectroscopy. Our studies provide physical insights into the kinetics and mechanisms of natural DNA metallization, in correlation with the multi-stage switching operations in the bulk phase, paving the way towards the development of versatile biomaterial composites with tunable physical properties for optical storage, plasmonics, and catalytic applications.
The accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.
The association between Helicobacter pylori (H. pylori) infection and osteoporosis risk remains equivocal. Our findings showed that H. pylori infection appears to have no effect on the risk of osteopenia and osteoporosis. Weight status may modify the association of H. pylori infection with low bone mass. Purpose: To evaluate the association between baseline H. pylori infection and osteoporosis risk in the general population. Methods: From January 1, 2019, to March 31, 2020, 1388 women and men aged over 50 years underwent a health examination. H. pylori infection was detected by the 13C urea breath test. Subjects were classified as having normal bone mineral density (BMD), osteopenia, and osteoporosis according to dual-energy X-ray absorptiometry. Chi-square tests and multinomial logistic regression models were performed to analyze the associations of H. pylori infection with osteopenia and osteoporosis. Results: Of the 1388 participants, 545 (39.3%) were H. pylori-positive. The prevalence rates of osteoporosis and osteopenia were 10.2% and 32.3%, respectively. No differences were observed in the rates of osteoporosis and osteopenia between H. pylori-positive and H. pylori-negative groups (P > 0.05). The association for the trend between the H. pylori infection and osteoporosis was only seen in the nonoverweight subgroup (trend χ2 = 5.455, P = 0.02). The odds ratio (OR) between H. pylori infection and osteoporosis was 1.31 (95% CI, 0.86-2.02, P = 0.211) after adjusting for sex, age, and body weight status. Conclusions: We demonstrate that H. pylori infection is not an independent risk factor for osteopenia and osteoporosis. This study did not support the association of H. pylori infection with osteoporosis.
Moiré lattice in artificially stacked monolayers of two-dimensional (2D) materials effectively modulates the electronic structures of materials, which is widely highlighted. Formation of the electronic Moiré superlattice promises the prospect of uniformity among different moiré cells across the lattice, enabling a new platform for novel properties, such as unconventional superconductivity, and scalable quantum emitters. Recently, epitaxial growth of the monolayer transition metal dichalcogenide (TMD) is achieved on the sapphire substrate by chemical vapor deposition (CVD) to realize scalable growth of highly-oriented monolayers. However, fabrication of the scalable Moiré lattice remains challenging due to the lack of essential manipulation of the well-aligned monolayers for clean interface quality and precise twisting angle control. Here, scalable and highly-oriented monolayers of TMD are realized on the sapphire substrates by using the customized CVD process. Controlled growth of the epitaxial monolayers is achieved by promoting the rotation of the nuclei-like domains in the initial growth stage, enabling aligned domains for further grain growth in the steady-state stage. A full coverage and distribution of the highly-oriented domains are verified by second-harmonic generation (SHG) microscopy. By developing the method for clean monolayer manipulation, hetero-stacked bilayer (epi-WS 2 /epi-MoS 2 ) is fabricated with the specific angular alignment of the two major oriented monolayers at the edge direction of 0°/ ± 60°. On account of the optimization for scalable Moiré lattice with a high-quality interface, the observation of interlayer exciton at low temperature illustrates the feasibility of scalable Moiré superlattice based on the oriented monolayers.
The state with effective total moment J eff = 1/2 stabilized by the spin-orbit coupling is known to suppress Jahn-Teller distortions and may induce a strong exchange anisotropy. This in turn may lead to the formation of an elusive spin-liquid state in real materials. While recent studies have demonstrated that such a situation can be realized in 3 d transition-metal compounds such as those based on Co ²⁺ and Cu ²⁺ , diagnosis of J eff = 1/2 state remains challenging. We show that resonant inelastic X-ray scattering is an effective tool to probe this state and apply it to CuAl 2 O 4 , material where Cu ²⁺ ions were previously proposed to be in the J eff = 1/2 state. Our results unambiguously demonstrate that, contrary to previous expectations, a competitive (to J eff = 1/2) Jahn-Teller state realizes in this compound.
Background Taichung Native 1 (TN1) is the first semidwarf rice cultivar that initiated the Green Revolution. As TN1 is a direct descendant of the Dee-geo-woo-gen cultivar, the source of the sd1 semidwarf gene, the sd1 gene can be defined through TN1. Also, TN1 is susceptible to the blast disease and is described as being drought-tolerant. However, genes related to these characteristics of TN1 are unknown. Our aim was to identify and characterize TN1 genes related to these traits. Results Aligning the sd1 of TN1 to Nipponbare sd1 , we found a 382-bp deletion including a frameshift mutation. Sanger sequencing validated this deleted region in sd1 , and we proposed a model of the sd1 gene that corrects errors in the literature. We also predicted the blast disease resistant (R) genes of TN1. Orthologues of the R genes in Tetep, a well-known resistant cultivar that is commonly used as a donor for breeding new blast resistant cultivars, were then sought in TN1, and if they were present, we looked for mutations. The absence of Pi54 , a well-known R gene, in TN1 partially explains why TN1 is more susceptible to blast than Tetep. We also scanned the TN1 genome using the PosiGene software and identified 11 genes deemed to have undergone positive selection. Some of them are associated with drought-resistance and stress response. Conclusions We have redefined the deletion of the sd1 gene in TN1, a direct descendant of the Dee-geo-woo-gen cultivar, and have corrected some literature errors. Moreover, we have identified blast resistant genes and positively selected genes, including genes that characterize TN1’s blast susceptibility and abiotic stress response. These new findings increase the potential of using TN1 to breed new rice cultivars.
To unveil a novel switching mechanism in liquid crystal (LC)-based phase shifters for the THz range, we analyse how the dimensions of the electrode structures enable a new type of switching, namely, THz in-plane and THz out-of-plane (TIP–TOP) switching. Specifically, we determine how varying these electrode dimensions influences the LC in-plane states with the corresponding phase shifts by calculating these effects in virtual devices. Interestingly, we found that significant dimensional effects of the in-plane electrode structures statically and dynamically influence the phase shift and response time of LC switching. Analysing the electromagnetic fields in the TIP–TOP cell clearly reveals that these dimensional effects are due to changes in the electric field strengths caused by lateral bus-line electrodes that were originally assumed not to contribute to the switching. Further, we discover that the ultimate dimensional effect produces a novel type of LC switching, which results in hexadirectional switching between the initial, intrinsic in-plane, and out-of-plane reorientations of the LCs, suggesting a broader range of phase shifts while maintaining a rapid response.
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6,220 members
Paramaguru Ganesan
  • Department of Chemistry
Alex J Y Lee
  • Physical Education
Jayachandran Jayakumar
  • Department of Chemistry
Yun-Ju Lee
  • Department of Industrial Engineering and Engineering Management
Shawn Lu
  • Institute of Biomedical Engineering
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