Browsing by Author "Chen, Wei-Jen"

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A 2-D Amplifying Array Using Multi-Ported Aperture-Coupled Patch Antennas
(2009-07-01)
Ho, Tan-Hsiung
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Chen, Wei-Jen
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Chung, Shyh-Jong
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電信工程研究所
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Institute of Communications Engineering
This paper proposes a new circuit-fed 2-D amplifying array architecture using the multi-ported aperture-coupled patch antennas. The power distribution achieved by this array is formed by stacking three kinds of basic cells repeatedly. Each cell, which serves as a radiator and also a power relay, has a multi-ported patch antenna and one or two amplifiers. The signal transmission coefficient of the cell from the input port to the output port is designed with a power level of 0dB and a phase of 360 degrees. An X-band 4 x 3 element array with uniform amplitude distribution is demonstrated. The measured results, such as the antenna gain and the radiation patterns, agree very well with the predicted ones, due to the precision design of the basic cells. The measured gain of the antenna array is 27.7 dBi(A) at the frequency of 10.4 GHz on the H-plane, with a half-power beamwidth of 14 degrees in the H-plane and 16 degrees in the E-plane.
Fe(3)O(4)/TiO(2) core/shell magnetic nanoparticle-based photokilling of pathogenic bacteria
(2010-12-01)
Chen, Wei-Jen
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Aims: We demonstrate a photokilling approach for pathogenic bacteria using magnetic nanoparticles as photokilling nanoprobes. Materials & methods: The nanoprobes are composed of iron oxide/titania (Fe(3)O(4)/TiO(2)) core/shell magnetic nanoparticles. The titanium layer on the magnetic nanoprobes plays two roles: as a photokilling agent and as an affinity substrate for pathogenic bacteria. The magnetic property of the nanoprobes allows the resultant nanoprobe-target species conjugates to be readily aggregated at a small spot under external magnetic field for conducting photokilling treatment. Therefore, damage to nontarget cells can be reduced. Results: The results show that Fe(3)O(4)/TiO(2) core/shell magnetic nanoparticles do not only have the capacity to target pathogenic bacteria, including Gram-negative, Gram-positive and antibiotic-resistant bacteria, but they can also be used to effectively inhibit the cell growth of the bacteria (>99.9%) targeted by the magnetic nanoparticles under irradiation of a low-power UV lamp (lambda(max) similar to 306 nm, 0.412 mW/cm(2)) within 15 min. Conclusion: The potential application of this approach is in the treatment of cutaneous bacterial infections.
Fe3O4/TiO2 core/shell magnetic nanoparticle-based photokilling of pathogenic bacteria
(2010-12-01)
Chen, Wei-Jen
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Chen, Yu-Chie
;
應用化學系
;
Department of Applied Chemistry
Aims: We demonstrate a photokilling approach for pathogenic bacteria using magnetic nanoparticles as photokilling nanoprobes. Materials & methods: The nanoprobes are composed of iron oxide/titania (Fe3O4/TiO2) core/shell magnetic nanoparticles. The titanium layer on the magnetic nanoprobes plays two roles: as a photokilling agent and as an affinity substrate for pathogenic bacteria. The magnetic property of the nanoprobes allows the resultant nanoprobe-target species conjugates to be readily aggregated at a small spot under external magnetic field for conducting photokilling treatment. Therefore, damage to nontarget cells can be reduced. Results: The results show that Fe3O4/TiO2 core/shell magnetic nanoparticles do not only have the capacity to target pathogenic bacteria, including Gram-negative, Gram-positive and antibiotic-resistant bacteria, but they can also be used to effectively inhibit the cell growth of the bacteria (>99.9%) targeted by the magnetic nanoparticles under irradiation of a low-power UV lamp (lambda(max) similar to 306 nm, 0.412 mW/cm(2)) within 15 min. Conclusion: The potential application of this approach is in the treatment of cutaneous bacterial infections.
Functional Fe3O4/TiO2 core/shell magnetic nanoparticles as photokilling agents for pathogenic bacteria
(2008-04-01)
Chen, Wei-Jen
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Tsai, Pei-Jane
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Chen, Yu-Chie
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應用化學系
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應用化學系分子科學碩博班
A photokilling approach for pathogenic bacteria is demonstrated using a new type of magnetic nanoprobe as the photokilling agent. In addition to their magnetic property, the nanoprobes have other features including a photocatalytic property and the capacity to target bacteria. The nanoprobes comprise iron oxide/titania (Fe3O4@TiO2) core/shell magnetic nanoparticles. As dopamine molecules can self-assemble onto the surface of the titania substrate, dopamine is used as the linker to immobilize succinic anhydride onto the surfaces of the Fe3O4@TiO2 nanoparticles. This is followed by the immobilization of IgG via amide bonding. We demonstrate that the IgG-Fe3O4@TiO2 magnetic nanoparticles not only have the capacity to target several pathogenic bacteria, but they also can effectively inhibit the cell growth of the bacteria targeted by the nanoparticles under irradiation of a low-power UV lamp within a short period. Staphylococcus saprophyticus, Streptococcus pyogenes, and antibiotic-resistant bacterial strains, such as multiantibiotic-resistant S. pyogenes and methicillin-resistant Staphylococcus aureus (MRSA), are used to demonstrate the feasibility of this approach.
Functional gold nanoclusters as antimicrobial agents, for antibiotic-resistant bacteria
(2010-07-01)
Chen, Wei-Yu
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Lin, Ju-Yu
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Chen, Wei-Jen
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Luo, Liyang
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Diau, Eirc Wei-Guang
Aims: Our aim was to demonstrate that lysozyme-directed generation of gold nanoclusters (Au NCs) are potential antimicrobial agents for antibiotic-resistant bacteria and broad labeling agents for pathogenic bacteria. Materials & methods: Lysozyme is an enzyme that is capable of hydrolyzing the cell walls of bacteria. In this study, we demonstrated the generation of functional Au NCs by using lysozyme as the sequester and the reducing agent for Au precursors at 40 degrees C. In addition, to shorten the reaction time, the reaction was conducted under microwave irradiation within a short period of time for the first time. Results: The bioactivity of the lysozyme on the Au NCs was retained. Therefore, the as-prepared lysozyme Au NCs with desirable fluorescence feature were successfully employed to be broad-band labeling agents for pathogenic bacteria. Furthermore, we also demonstrated that the lysozyme Au NCs can be used to effectively inhibit the cell growth of notorious antibiotic-resistant bacteria, including pan-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis. Conclusion: The potential of employing the lysozyme Au NCs for bacterial labeling and as antimicrobial agents is expected.
Functional Nanoparticle-Based Proteomic Strategies for Characterization of Pathogenic Bacteria
(2008-12-15)
Chen, Wei-Jen
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Tsai, Pei-Jane
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Although matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) can be employed to rapidly characterize pathogenic bacteria, bacterial cultures are generally required to obtain sufficient quantities of the bacterial cells prior to MALDI MS analysis. If this time-consuming step could be eliminated, the length of time required for identification of bacterial strains would be greatly reduced. In this paper, we propose an effective means of rapidly identifying bacteria-one that does not require bacterial culturing-using functional nanoparticle-based proteomic strategies that are characterized by extremely short analysis time. In this approach, we used titania-coated magnetic iron oxide nanoparticles (Fe(3)O(4)@TiO(2) NPs) as affinity probes to concentrate the target bacteria. The magnetic properties of the Fe(3)O(4)@TiO(2) NPs allow the conjugated target species to be rapidly isolated from the sample solutions under a magnetic field. Taking advantage of the absorption of the magnetic Fe(3)O(4) NPs in the microwave region of the electromagnetic spectrum, we performed the tryptic digestion of the captured bacteria under microwave heating for only 1-1.5 min prior to MALDI MS analysis. We identified the resulting biomarker ions by combining their MS/MS analysis results with protein database searches. Using this technique, we identified potential biomarker ions representing five Gram-negative bacteria: Escherichia coli O157:H7, uropathogenic E. coli, Shigella sonnei, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Finally, we demonstrated the practical feasibility of using this approach to rapidly characterize bacteria in clinical samples.
Glutathione-bound gold nanoclusters for selective-binding and detection of glutathione S-transferase-fusion proteins from cell lysates
(2009)
Chen, Cheng-Tai
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Chen, Wei-Jen
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Liu, Chao-Zong
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Chang, Ling-Ya
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Chen, Yu-Chie
A straightforward method for the rapid detection of the presence of glutathione S-transferase (GST)-tagged proteins from sample solutions using glutathione (GSH)-bound gold nanoclusters (Au@GSH NCs) with luminescence properties as the detection probes by simple observation with the naked eye was proposed in this study.
Identification of Pseudomonas aeruginosa using functional magnetic nanoparticle-based affinity capture combined with MALDI MS analysis
(2009)
Liu, Jr-Chi
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Chen, Wei-Jen
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Li, Chen-Wei
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Mong, Kwok-Kong Tony
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Tsai, Pei-Jane
PA-IL is a galactophilic lectin that is found on the outer membrane of Pseudomonas aeruginosa. Pigeon ovalbumin (POA), a phosphoprotein, contains high levels of terminal Gala(1 -> 4) Gal units. Thus, magnetic nanoparticles with immobilized POA can be used as affinity probes for P. aeruginosa, functioning via the recognition of galactophilic PA-IL. We fabricated POA-bound nanoparticles (NPs) by immobilizing POA onto the surface of core/shell magnetic iron oxide/alumina NPs via metal phosphate chelation. We then used the generated NPs to probe target bacteria from complex samples. The trapped bacterial cells were characterized based on their mass peak profiles obtained from MALDI MS analyses. In addition, we confirmed the determination of P. aeruginosa using a proteomic strategy: combining the resultant MALDI MS/MS spectra of its tryptic digest with protein database searching. The feasibility of using this approach to rapidly characterize P. aeruginosa from clinical samples without the need to perform culturing steps was also demonstrated.
Phylogenetic relationships of Acheilognathidae (Cypriniformes: Cyprinoidea) as revealed from evidence of both nuclear and mitochondrial gene sequence variation: Evidence for necessary taxonomic revision in the family and the identification of cryptic species
(2014-12-01)
Chang, Chia-Hao
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Li, Fan
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Shao, Kwang-Tsao
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Lin, Yeong-Shin
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Morosawa, Takahiro
Bitterlings are relatively small cypriniform species and extremely interesting evolutionarily due to their unusual reproductive behaviors and their coevolutionary relationships with freshwater mussels. As a group, they have attracted a great deal of attention in biological studies. Understanding the origin and evolution of their mating system demands a well-corroborated hypothesis of their evolutionary relationships. In this study, we provide the most comprehensive phylogenetic reconstruction of species relationships of the group based on partitioned maximum likelihood and Bayesian methods using DNA sequence variation of nuclear and mitochondrial genes on 41 species, several subspecies and three undescribed species. Our findings support the monophyly of the Acheilognathidae. Two of the three currently recognized genera are not monophyletic and the family can be subdivided into six clades. These clades are further regarded as genera based on both their phylogenetic relationships and a reappraisal of morphological characters. We present a revised classification for the Acheilognathidae with five genera/lineages: Rhodeus, Acheilognathus (new constitution), Tanakia (new constitution), Paratanakia gen. nov., and Pseudorhodeus gen. nov. and an unnamed clade containing five species currently referred to as "Acheilognathus". Gene trees of several bitterling species indicate that the taxa are not monophyletic. This result highlights a potentially dramatic underestimation of species diversity in this family. Using our new phylogenetic framework, we discuss the evolution of the Acheilognathidae relative to classification, taxonomy and biogeography. (C) 2014 Elsevier Inc. All rights reserved.
Poster - RECO: A Reconfigurable Core Network for Future 5G Communication Systems
(2017-01-01)
Wu, Chia-Han
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Chen, Wei-Jen
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Chen, Jyh-Cheng
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資訊工程學系
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Department of Computer Science
It is envisioned in the fiittire, that not only smartphones will conned to cellular networks, but all kinds of different wearable devices, sensors, vehicles, home appliances, VR headsets, robots, will also connect to cellular networks. Because the characteristics of these devices differ largely, people argue that future 5G systems should be designed to elastically accommodate to the different users. In this paper, we propose a reconfigurable core network called RECO that demonstrates how to implement customized virtual core network entities efficiently to suit for users with different characteristics. We then build a testbed to verify our proposed RECO architecture. Finally, we will open source our RECO in the near future so that the research community can take benefit out of it.