90 results on '"Wei-Chung Chang"'
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2. Dietary Exposure and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Black Tea Consumed in Taiwan
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Drewyan Minelly Harrison, Wei-Chung Chang, and Hsin-Tang Lin
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Camellia sinensis ,polycyclic aromatic hydrocarbons (PAHs) ,risk assessment ,margin of exposure (MOE) ,Chemical technology ,TP1-1185 - Abstract
Polycyclic aromatic hydrocarbons (PAHs) are organic compounds found in many foods and drinks, and there have been some concerns over these compounds due to their carcinogenic nature. This study evaluated the concentrations of PAH4 (BaP, BaA, BbF, and CHR) in different black tea infusions and drinks based on the origin of the tea. The release of PAH4 from tea leaves to tea infusions was significantly low, with the highest transfer being 25.81%. The mean concentrations of BaP and PAH4 in tea infusions were used to conduct a risk assessment for the Taiwanese population, which showed that the 19–65 age group had the highest estimated intake of PAH4 and BaP among all age groups. These results, however, also showed margin of exposure (MOE) values well above the benchmark of 10,000. This indicated that PAH exposure from black tea consumption for the Taiwanese population constitutes a low-level health concern.
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- 2024
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3. Red Phosphorus Potassium‐Ion Battery Anodes
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Wei‐Chung Chang, Jen‐Hsuan Wu, Kuan‐Ting Chen, and Hsing‐Yu Tuan
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PC bonding ,PIB anodes ,red phosphorus ,wet‐ball milling process ,Science - Abstract
Abstract Phosphorus (P) possesses the highest theoretical specific capacity (865 mA h g−1) among all the elements for potassium‐ion battery (PIB) anodes. Although Red P (RP) has intrinsic advantages over its allotropes, including low cost and nontoxicity, and simpler preparation, it is yet unknown to effectively activate it into a high‐performance PIB anode. Here, high‐performance RP PIB anodes are reported. Two important factors are found to facilitate RP react with K‐ions reversibly: i) nanoscale RP particles are dispersed evenly in a conductive carbon matrix composed of multiwall carbon nanotubes and Ketjen black that provide an efficient electrical pathway and a tough scaffold. ii) The results of X‐ray photoelectron spectroscopy spectrum and the electrochemical performance perhaps show that no PC bond formation is beneficial to allow K‐ions to react with RP effectively. As a result, the RP/C electrodes deliver a reversible specific capacity of ≈750 mA h g−1 and exhibit a high‐rate capability (≈300 mA h g−1 at 1000 mA g−1). RP/C full cells using potassium manganese hexacyanoferrate as cathode show a long cycling life (680 cycles) at a current density of 1000 mA g−1, in addition, a pouch‐type battery is built to demonstrate practical applications.
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- 2019
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4. Glucosides from the unripe fruit juice of Carica papaya Linn. (Caricaceae) cultivar ‘Red Lady’ with antioxidant activity
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Mary Grace M. Galang, Allan Patrick G. Macabeo, Wei-Chung Chang, Minoru Isobe, and Ma Alicia M. Aguinaldo
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Carica papaya ,Red Lady papaya cultivar ,DPPH radical ,Hydroxyl radical ,Isopropyl 5-β-D-glucopyranosyloxy-2-hydroxybenzoate and methyl β-D-glucopyranoside ,Nutrition. Foods and food supply ,TX341-641 - Abstract
Natural antioxidants from Carica papaya (‘Red Lady’ cultivar) were investigated. Reversed phase chromatography of the fruit juice gave 12 fractions that were subjected to DPPH and hydroxyl radical scavenging assays. Purification of Cp7 afforded isopropyl 5-β-D-glucopyranosyloxy-2-hydroxybenzoate (1) while the methanol fractions Cp8–10 afforded methyl β-D-glucopyranoside (2). This is the first report on the isolation of these compounds from C. papaya. Compound (1) showed significant DPPH radical scavenging capacity. Compound (2) was an isolate giving 77% DPPH and 81% hydroxyl radical scavenging activities, which are close or equal to the values for the standard ascorbic acid (98% DPPH and 81% hydroxyl radical scavenging activities).
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- 2016
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5. Co-pyrolysis of sewage sludge and food waste digestate to synergistically improve biochar characteristics and heavy metals immobilization
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Wang, Xingdong, Wei-Chung Chang, Victor, Li, Zhiwei, Song, Yang, Li, Chunxing, and Wang, Yin
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- 2022
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6. Exploring temporal patterns of bacterial and fungal DNA accumulation on a ventilation system filter for a Singapore university library.
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Luhung, Irvan, Wu, Yan, Xu, Siyu, Yamamoto, Naomichi, Wei-Chung Chang, Victor, and Nazaroff, William W
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DNA ,Bacterial ,DNA ,Fungal ,RNA ,Ribosomal ,16S ,Fluorometry ,Environmental Microbiology ,Environmental Monitoring ,Universities ,Construction Materials ,Singapore ,DNA ,Bacterial ,Fungal ,RNA ,Ribosomal ,16S ,General Science & Technology - Abstract
IntroductionVentilation system filters process recirculated indoor air along with outdoor air. This function inspires the idea of using the filter as an indoor bioaerosol sampler. While promising, there remains a need to investigate several factors that could limit the accuracy of such a sampling approach. Among the important factors are the dynamics of microbial assemblages on filter surfaces over time and the differential influence of outdoor versus recirculated indoor air.MethodsThis study collected ventilation system filter samples from an air handling unit on a regular schedule over a 21-week period and analyzed the accumulation patterns of biological particles on the filter both quantitatively (using fluorometry and qPCR) and in terms of microbial diversity (using 16S rDNA and ITS sequencing).ResultsThe quantitative result showed that total and bacterial DNA accumulated monotonically, rising to 41 ng/cm2 for total DNA and to 2.8 ng/cm2 for bacterial DNA over the 21-week period. The accumulation rate of bacterial DNA correlated with indoor occupancy level. Fungal DNA first rose to 4.0 ng/cm2 before showing a dip to 1.4 ng/cm2 between weeks 6 and 10. The dip indicated a possible artifact of this sampling approach for quantitative analysis as DNA may not be conserved on the filter over the months-long service period. The sequencing results indicate major contributions from outdoor air for fungi and from recirculated indoor air for bacteria. Despite the quantitative changes, the community structure of the microbial assemblages was stable throughout the 21-week sampling period, highlighting the robustness of this sampling method for microbial profiling.ConclusionThis study supports the use of ventilation system filters as indoor bioaerosol samplers, but with caveats: 1) an outdoor reference is required to properly understand the contribution of outdoor bioaerosols; and 2) there is a need to better understand the persistence and durability of the targeted organisms on ventilation system filters.
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- 2018
7. Comparison and modeling of leachate transportation dominated by the field permeability with an anisotropic characteristic based on a large-scale field trial study
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Yin, Ke, Chan, Wei-Ping, Dou, Xiaomin, Lisak, Grzegorz, and Wei-Chung Chang, Victor
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- 2020
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8. Cr, Cu, Hg and Ni release from incineration bottom ash during utilization in land reclamation – based on lab-scale batch and column leaching experiments and a modeling study
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Yin, Ke, Chan, Wei Ping, Dou, Xiaomin, Ren, Fei, and Wei-Chung Chang, Victor
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- 2018
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9. Massive collaborative animation projects: changing paradigms in animation education.
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William J. Joel, Miho Aoki, Jacob Pollak, Johannes DeYoung, Anna Ursyn, and Wei-Chung Chang
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- 2018
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10. Teaching Action of Virtual Reality Video Creation Based on Viewers’ Cognitive Behavior
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Yu-Di Huang, Guang-Dah Chen, Wei-Chung Chang, and Yikang Sun
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General Medicine - Published
- 2022
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11. Exploring temporal patterns of bacterial and fungal DNA accumulation on a ventilation system filter for a Singapore university library.
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Irvan Luhung, Yan Wu, Siyu Xu, Naomichi Yamamoto, Victor Wei-Chung Chang, and William W Nazaroff
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Medicine ,Science - Abstract
INTRODUCTION:Ventilation system filters process recirculated indoor air along with outdoor air. This function inspires the idea of using the filter as an indoor bioaerosol sampler. While promising, there remains a need to investigate several factors that could limit the accuracy of such a sampling approach. Among the important factors are the dynamics of microbial assemblages on filter surfaces over time and the differential influence of outdoor versus recirculated indoor air. METHODS:This study collected ventilation system filter samples from an air handling unit on a regular schedule over a 21-week period and analyzed the accumulation patterns of biological particles on the filter both quantitatively (using fluorometry and qPCR) and in terms of microbial diversity (using 16S rDNA and ITS sequencing). RESULTS:The quantitative result showed that total and bacterial DNA accumulated monotonically, rising to 41 ng/cm2 for total DNA and to 2.8 ng/cm2 for bacterial DNA over the 21-week period. The accumulation rate of bacterial DNA correlated with indoor occupancy level. Fungal DNA first rose to 4.0 ng/cm2 before showing a dip to 1.4 ng/cm2 between weeks 6 and 10. The dip indicated a possible artifact of this sampling approach for quantitative analysis as DNA may not be conserved on the filter over the months-long service period. The sequencing results indicate major contributions from outdoor air for fungi and from recirculated indoor air for bacteria. Despite the quantitative changes, the community structure of the microbial assemblages was stable throughout the 21-week sampling period, highlighting the robustness of this sampling method for microbial profiling. CONCLUSION:This study supports the use of ventilation system filters as indoor bioaerosol samplers, but with caveats: 1) an outdoor reference is required to properly understand the contribution of outdoor bioaerosols; and 2) there is a need to better understand the persistence and durability of the targeted organisms on ventilation system filters.
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- 2018
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12. Journeys With Asian Doctoral Student Advisees
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Karen Keifer-Boyd, Wei-Chung Chang, Hui-Chun Hsiao, Hong Kyu Koh, Hyunji Kwon, Christine Liao, Yen-Ju Lin, Jihyun Sohn, and Shwu-Huoy Tzou
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- 2022
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13. Sensemaking for Strategy in an Agent-based Organization.
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Hsiao-Tzu Huang and Wei-Chung Chang
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- 2006
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14. DNA accumulation on ventilation system filters in university buildings in Singapore.
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Irvan Luhung, Yan Wu, Siyu Xu, Naomichi Yamamoto, Victor Wei-Chung Chang, and William W Nazaroff
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Medicine ,Science - Abstract
Biological particles deposit on air handling system filters as they process air. This study reports and interprets abundance and diversity information regarding biomass accumulation on ordinarily used filters acquired from several locations in a university environment.DNA-based analysis was applied both to quantify (via DNA fluorometry and qPCR) and to characterize (via high-throughput sequencing) the microbial material on filters, which mainly processed recirculated indoor air. Results were interpreted in relation to building occupancy and ventilation system operational parameters.Based on accumulated biomass, average DNA concentrations per AHU filter surface area across nine indoor locations after twelve weeks of filter use were in the respective ranges 1.1 to 41 ng per cm2 for total DNA, 0.02 to 3.3 ng per cm2 for bacterial DNA and 0.2 to 2.0 ng DNA per cm2 for fungal DNA. The most abundant genera detected on the AHU filter samples were Clostridium, Streptophyta, Bacillus, Acinetobacter and Ktedonobacter for bacteria and Aspergillus, Cladosporium, Nigrospora, Rigidoporus and Lentinus for fungi. Conditional indoor airborne DNA concentrations (median (range)) were estimated to be 13 (2.6-107) pg/m3 for total DNA, 0.4 (0.05-8.4) pg/m3 for bacterial DNA and 2.3 (1.0-5.1) pg/m3 for fungal DNA.Conditional airborne concentrations and the relative abundances of selected groups of genera correlate well with occupancy level. Bacterial DNA was found to be more responsive than fungal DNA to differences in occupancy level and indoor environmental conditions.
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- 2017
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15. Compact microstrip bandpass filters using triple‐mode resonator with lumped elements
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Wen-Hua Tu and Wei Chung Chang
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Physics ,Resonator ,Band-pass filter ,business.industry ,Mode (statistics) ,Optoelectronics ,Electrical and Electronic Engineering ,Condensed Matter Physics ,business ,Atomic and Molecular Physics, and Optics ,Microstrip ,Electronic, Optical and Magnetic Materials - Published
- 2020
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16. Dual-band bandpass filter for software defined radio and 5G
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Wei Chung Chang and Wen Hua Tu
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Filter design ,Waveguide (electromagnetism) ,Resonator ,Band-pass filter ,Computer science ,Electronic engineering ,Insertion loss ,Figure of merit ,Software-defined radio ,Electrical and Electronic Engineering ,Microstrip - Abstract
This paper presents the filter design in the student design competition of EuMW 2019. This contest motivates students for the design and implementation of a dual-band bandpass filter able to get outstanding performance, where different implementation technologies, such as microstrip, coplanar, multilayer microstrip, substrate integrated waveguide, and some others can be effectively employed. Filters are evaluated by considering a figure of merit (FoM) defined by the insertion loss level, selectivity, spurious-free response, and size. To this end, three viable dual-band bandpass filters with different feeding technologies, resonators, and design topologies are investigated for the optimal FoM.
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- 2020
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17. Examining particulate matter exposures in & around an opencast coal mine in Southern India
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Kamlika Gupta, Prince Vijay, Rohit Bodhale, Victor Wei-Chung Chang, Mohan Yellishetty, and Harish Phuleria
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Chemical Health and Safety ,Public Health, Environmental and Occupational Health ,Public aspects of medicine ,RA1-1270 ,Safety, Risk, Reliability and Quality ,Safety Research - Published
- 2022
18. Applying Evolutionary Computing to Complex Systems Design.
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Alistair G. Sutcliffe, Wei-Chung Chang, and Richard Stuart Neville
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- 2007
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19. Co-pyrolysis of sewage sludge and food waste digestate to synergistically improve biochar characteristics and heavy metals immobilization
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Xingdong Wang, Victor Wei-Chung Chang, Zhiwei Li, Yang Song, Chunxing Li, and Yin Wang
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Waste Management and Disposal - Abstract
Food waste digestate (FWD) is a desirable additive in sewage sludge (SS)-based biochar preparation owing to its high contents of intrinsic inorganic minerals and lignocellulosic compounds. In this study, we investigated the co-pyrolysis of SS with FWD at different mixing ratios (4:0, 3:1, 2:2, 1:3, and 0:4; SS:FWD w/w) at 550 °C to synergistically improve the biochar characteristics and immobilize the heavy metals in the SS. The results showed that co-pyrolysis of SS with FWD greatly increased the aromaticity and pH (by 13.22-26.56%) of the blended biochar, and significantly reduced the contents of total and bioavailable heavy metals. The addition of FWD effectively enhanced the conversion of heavy metals from less stable fractions to more stable forms, but led to the transformation of Cr from the residual fraction (F4) to the oxidizable fraction (F3) when the FWD:SS ratio was ≥ 3:1. Overall, the formation of co-crystal compounds, stable kaolinite, and metal oxides together with the enhancement of biochar characteristics during co-pyrolysis significantly reduced the heavy metal-associated ecological risk (potential ecological risk index lower than 15.51) and phytotoxicity (germination index higher than 139.41%) of the blended biochar. These findings suggest that high levels of mineral components in FWD greatly immobilize more heavy metals in biochar.
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- 2021
20. Chelation-Tamoxifen Conjugates for Imaging of Estrogen Receptors
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Yen-Chun Lee, Ming Hsien Lin, Chorng-Jer Hwang, Skye Hsin Hsien Yeh, Wei-Chung Chang, Min-Ching Chung, Chi-Shiang Ke, Shu-Meng Hsu, and David J. Yang
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Cancer Research ,medicine.drug_class ,Estrogen receptor ,Apoptosis ,Cell Line, Tumor ,medicine ,Endocrine system ,Humans ,Radiology, Nuclear Medicine and imaging ,Chelating Agents ,Pharmacology ,Ovarian Neoplasms ,business.industry ,General Medicine ,Organotechnetium Compounds ,Antiestrogen ,medicine.disease ,Tamoxifen ,Oncology ,Receptors, Estrogen ,Estrogen ,Cancer research ,Female ,Molecular imaging ,Differential diagnosis ,business ,Ovarian cancer ,hormones, hormone substitutes, and hormone antagonists ,medicine.drug - Abstract
Background: The differential diagnosis of estrogen receptor-positive (ER+) pathway-activated systems by using a labeled antiestrogen helps to select the patients for optimal response to endocrine t...
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- 2021
21. Facile Synthesis of Cu Nanocrystals with Morphology Evolution from Transitional Truncated Octahedra to Octahedra
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Shu-Chen Lu, Hsing-Yu Tuan, Kuan-Ting Chen, Wei-Chung Chang, and Po-Yuan Yang
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Colloid ,Crystallography ,Morphology (linguistics) ,Materials science ,Article Subject ,Nanocrystal ,Octahedron ,lcsh:Technology (General) ,lcsh:T1-995 ,Nanoparticle ,General Materials Science - Abstract
Growth of Cu polyhedral structures with well-defined and controllable shapes faced tremendous synthetic challenges in colloid nanocrystal synthesis in the past few decades. In this article, we report a facile approach for the synthesis of Cu nanocrystals with systematic morphological evolution. Transitional truncated octahedral, edge- and corner-truncated octahedral, all-corner-truncated octahedral, and octahedral structures were obtained in a solution-based reduction reaction by precise tuning reaction time. Four distinct morphologies of nanocrystals have been characterized by SEM technique. The optical properties of these various morphologies of nanocrystals were also investigated, and it indicates that the SPR band shifts red while the shape of nanoparticles evolves from transitional truncated octahedral to octahedral, whose resonant bands are transferred from 590 nm to 620 nm.
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- 2019
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22. Free standing Si (Ge) nanowire/Cu nanowire composites as lithium ion battery anodes
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Wei-Chung Chang, Hong-Jie Yang, Sheng-Bor Huang, Kuan-Ting Chen, Hsing-Yu Tuan, and Chun-Yu Tsai
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Materials science ,Silicon ,Annealing (metallurgy) ,General Chemical Engineering ,Nanowire ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,General Chemistry ,Current collector ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Lithium-ion battery ,0104 chemical sciences ,Anode ,chemistry ,Electrode ,Composite material ,0210 nano-technology - Abstract
Silicon (Si) and germanium (Ge) can alloy with lithium to achieve high theoretical specific capacities (3579 mAh/g for Li15Si4 and 1384 mAh/g for Li15Ge4), which are several times greater than commercial graphite (372 mAh/g). However, they exhibit significant volume and crystal structural change during cycling processes, leading to structural pulverization and loss of electrical conduction paths between individual active materials and current collector. We report a non-carbon based free standing electrodes fabricated by directly mixing Si and Ge nanowires with Cu nanowires as lithium ion battery anodes. The one dimensional nanostructure of Si (Ge) and Cu provide good charge transport along their length and many contact points were formed between NWs after annealing process. The nanowire composites have several advantages compared to the conventional electrode that slurry materials are coated on a metal foil. For example, the weight is lighter than conventional electrodes because it does not need a current collector and is fabricated without any additives, and binders. Moreover, the space among the nanowires can accommodate the volume contraction of Si (Ge) during alloying and dealloying process and enhance the electrolyte penetration.
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- 2019
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23. Lithium-Ion Battery Anodes of Stacked Nanowire Laminate for Ultrahigh Areal Capacities
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Shih-Pin Lu, Hsun-Chen Chu, Wei-Chung Chang, and Hsing-Yu Tuan
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Materials science ,General Chemical Engineering ,Stacking ,Nanowire ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Lithium-ion battery ,law.invention ,law ,Environmental Chemistry ,Electrical conductor ,Renewable Energy, Sustainability and the Environment ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,Cathode ,0104 chemical sciences ,Anode ,chemistry ,Electrode ,Optoelectronics ,0210 nano-technology ,business - Abstract
Herein, a stacked Ge/Cu nanowire (NW) laminate made by stacking several Ge/Cu nanowire laminates accompanied by the conductive glue adhesives is used to achieve high capacity output per unit area (>10 mA h cm–2). The combination of Cu NWs and conductive adhesives constructs a tough and conducting network through the electrode, and the stacked Ge/Cu nanowire laminate electrodes can load an ultrahigh mass of 14.8 mg Ge per unit area and provide an areal capacity output over 16 mA h cm–2. A full-cell with an areal capacity of 11 mA h cm–2 built by stacked Ge/Cu nanowire laminate anode and Li(Ni0.5Co0.3Mn0.2)O2 cathode was prepared and used to supply electricity for electronic devices, demonstrating their potential to be a candidate anode for high areal capacity Li-ion microbatteries that can be used for high-tech and integrated microsystems with limited space.
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- 2018
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24. Multi-walled carbon nanotube-wrapped SiP2 as a superior anode material for lithium-ion and sodium-ion batteries
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Ching-Yu Wang, Yuan-Hsing Yi, Tzu-Lun Kao, Hsing-Yu Tuan, and Wei-Chung Chang
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Materials science ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,Sodium-ion battery ,chemistry.chemical_element ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Lithium-ion battery ,Cathode ,0104 chemical sciences ,law.invention ,Anode ,chemistry ,law ,Lithium ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Composite material ,0210 nano-technology ,Energy source ,Electrical conductor - Abstract
SiP2 has a high specific theoretical capacity of 2902 mA h g-1 as an anode material for lithium-ion batteries and 1788 mA h g-1 for sodium-ion batteries, respectively, but demonstrates very poor cycling stability in the entire voltage range (0–2 V). Here, we report high performance SiP2 anodes for lithium-ion batteries and sodium-ion batteries with good cycling stability by wrapping SiP2 with multi-walled carbon nanotube (MWCNT) on the surface of SiP2 via a ball milling prociess. MWCNT provides a robust network to connect fragment SiP2 with surrounding electrical conductor and serves as an effective conductive agent. MWCNT-wrapped SiP2 shows a reversible capacity of 1622 mA h g-1 after 100 cycles at 0.5 A g−1 in lithium-ion batteries and 925 mA h g-1 after 200 cycles at 0.2 A g−1 in sodium-ion batteries. In addition, rate capability is significantly enhanced. Furthermore, both coin-type and pouch-type full cells are assembled using SiP2 anodes which are coupled respectively with a cathode of LiFePO4 for lithium-ion batteries and a cathode of Na2/3Ni1/3Mn2/3O2 for sodium-ion batteries, and supplied as a reliable energy source for electronic uses to evaluate practical applications.
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- 2018
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25. Synthesis of Mesoporous Germanium Phosphide Microspheres for High-Performance Lithium-Ion and Sodium-Ion Battery Anodes
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Wei-Chung Chang, Sheng-Bor Huang, Hsing-Yu Tuan, and Kuan-Wei Tseng
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Materials science ,Phosphide ,General Chemical Engineering ,chemistry.chemical_element ,Sodium-ion battery ,Germanium ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Anode ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Lithium ,0210 nano-technology ,Mesoporous material ,Faraday efficiency - Abstract
Germanium phosphide is a potential anode material because of its high theoretical capacity and incredible rate capability on lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, the huge volume change that occurs while germanium phosphide is converted to Na3P or Li3P directly leads to poor cyclability and limits further applications. Herein, mesoporous germanium phosphide (MGePx) microspheres with diameter size ranging from 0.5 to 1.5 μm were first prepared by a one-step and template-free approach. MGePx microspheres were composed of nanoparticles of around 10 nm with a narrow distribution of pore sizes of around 4 nm. The MGePx possessed superior features in LIBs/SIBs since it shortens the diffusion path of the energy carrier and provides the buffer space for the transport of Li/Na ions. MGePx showed attractive electrochemical properties as a potential anode candidate, such as a high first-cycle Coulombic efficiency of 82.63%, high reversible capacity (1400 mA h g–1 after 150 cycles at ...
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- 2018
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26. Significantly improved performance of red phosphorus sodium-ion anodes with the addition of iron
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Hsing-Yu Tuan, Yuan-Hsing Yi, Wei-Chung Chang, and Li-Chu Chin
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Battery (electricity) ,Materials science ,General Chemical Engineering ,Phosphorus ,Sodium ,chemistry.chemical_element ,Sodium-ion battery ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Energy storage ,0104 chemical sciences ,Anode ,chemistry ,Chemical engineering ,Lithium ,0210 nano-technology - Abstract
Sodium-ion battery is the most promising alternative to lithium-ion battery for the similar chemical properties to lithium and low cost due to the earth abundance of sodium. Red phosphorus (RP) is regarded as a potential candidate for sodium-ion batteries because it has the highest theoretical capacity (∼2600 mA h/g), but commercially available RP is electrochemical inactivity with sodium as a result of the insulating nature. Among the P-based anodes for SIBs, they were all in the form of carbon−P composites. Herein, we report that commercial RP mixed with appropriate amount of iron developed by high-energy ball milling can deliver a reversible capacity of 1642 mA h g −1 over 30 cycles. EIS measurement results indicated that Fe content composites has higher sodium diffusion coefficient. When utilized as a sodium ion battery anode, 9.1% Fe-adding RP composites exhibited the best electrochemical performance achieved 1582, 1419, 884 and 676 mA h g −1 specific desodiation capacity at 0.2, 0.6, 1, 6 and 10 A g −1 current density in rate capability tests. This study opens a new approach to activate the sodium-ion storage of phosphorus, which will enable phosphorus-related materials to be used in more innovative energy storage systems.
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- 2018
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27. Solution Synthesis of Iodine-Doped Red Phosphorus Nanoparticles for Lithium-Ion Battery Anodes
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Wei-Chung Chang, Kuan-Wei Tseng, and Hsing-Yu Tuan
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Materials science ,Silicon ,Mechanical Engineering ,Inorganic chemistry ,Nanoparticle ,chemistry.chemical_element ,Bioengineering ,Germanium ,02 engineering and technology ,General Chemistry ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Lithium-ion battery ,0104 chemical sciences ,Anode ,chemistry.chemical_compound ,chemistry ,Bromide ,General Materials Science ,0210 nano-technology ,Ethylene glycol - Abstract
Red phosphorus (RP) is a promising anode material for lithium-ion batteries due to its earth abundance and a high theoretical capacity of 2596 mA h g–1. Although RP-based anodes for lithium-ion batteries have been reported, they were all in the form of carbon–P composites, including P–graphene, P–graphite, P–carbon nanotubes (CNTs), and P–carbon black, to improve P’s extremely low conductivity and large volume change during cycling process. Here, we report the large-scale synthesis of red phosphorus nanoparticles (RPNPs) with sizes ranging from 100 to 200 nm by reacting PI3 with ethylene glycol in the presence of cetyltrimethylammonium bromide (CTAB) in ambient environment. Unlike the insulator behavior of commercial RP (conductivity of
- Published
- 2017
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28. A flexible all inorganic nanowire bilayer mesh as a high-performance lithium-ion battery anode
- Author
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Tzu-Lun Kao, Yow Lin, Wei-Chung Chang, and Hsing-Yu Tuan
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Battery (electricity) ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Bilayer ,Nanowire ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanowire battery ,Cathode ,0104 chemical sciences ,law.invention ,Anode ,chemistry ,law ,Electrode ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
Herein, we report a flexible, binder-free inorganic nanowire bilayer mesh as a lithium-ion battery anode that provides high practical areal, gravimetric, and volumetric capacities. The configuration of the binder-free inorganic nanowire bilayer mesh anode is solely composed of two layers of nanowire fabric with one layer of germanium (Ge) nanowires and the other of copper nanowires. This nanowire electrode exhibited a high specific capacity of 1153 mA h g−1 when cycled at 0.1C, good rate-capability (359 mA h g−1 at a charge current density of 20 A g−1, 20C), and long-term cycling life of 1000 cycles and 1300 cycles when operated at 1C and 10C (discharge rate was fixed at 1C), respectively. The tightly tangled bilayer Ge/Cu nanowire mesh provides not only a strong structure to prevent the detachment of active materials, but also better electrical conduction because the two layers of nanowires penetrate each other instead of making a clear boundary. Moreover, the loading of Ge nanowires on a 1 cm2 Cu nanowire mesh is tunable within a wide range from 0.5 to 6 mg, corresponding to high areal capacities from 0.5 to 6 mA h cm−2 and volumetric capacity from 217 to 539 mA h cm−3, which is nearly twice as high as that of commercial graphite anodes with one side coating (255 mA h cm−3) and 10 times higher than those of reported Ge flexible electrodes made with CNFs. A full-cell battery with a capacity of 60 mA h composed of a Ge/Cu fabric anode and Li(Ni0.5Co0.3Mn0.2)O2 cathode was assembled to power up a power tool and LED arrays; this provided a proof-of-concept example to implement the nanowire mesh structure into a current battery system.
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- 2017
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29. A germanium nanoparticles/molybdenum disulphide (MoS2) nanocomposite as a high-capacity, high-rate anode material for lithium-ion batteries
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Guo-An Li, Meng-Hsun Hsieh, Wei-Chung Chang, and Hsing-Yu Tuan
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Nanocomposite ,Materials science ,Renewable Energy, Sustainability and the Environment ,Annealing (metallurgy) ,Metallurgy ,chemistry.chemical_element ,Nanoparticle ,Germanium ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,Anode ,chemistry ,Chemical engineering ,Molybdenum ,law ,General Materials Science ,0210 nano-technology - Abstract
A facile synthesis of Ge/MoS2 nanocomposites is developed by blending Ge nanoparticles into MoS2 nanosheets in solution at room temperature followed by annealing at 350 °C. The decoration with Ge nanoparticles in this compound can synergistically improve the electrochemical performance of LIBs because of increased conductivity and structure stability. Ge/MoS2 nanocomposites exhibit a high reversible capacity of 1362 mA h g−1 cycled at 0.2 A g−1 after 50 cycles. Even at high rate capability (>1 A g−1), the battery performance of Ge/MoS2 from 0.2 A g−1 to 15 A g−1 is superior to the performances of the reported graphene-based and other nanoparticle-decorated MoS2 anodes. Finally, a coin-type full-cell with a high areal capacity (∼3 mA h cm−2) and a high volumetric capacity (∼1700 mA h cm−3) was also achieved with a Ge/MoS2 anode and a Li(MnCoNi)O2 cathode.
- Published
- 2017
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30. Design as narrative: making thinking visible.
- Author
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Wei-Chung Chang
- Published
- 2006
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31. Potassium‐Ion Batteries: Red Phosphorus Potassium‐Ion Battery Anodes (Adv. Sci. 9/2019)
- Author
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Hsing-Yu Tuan, Kuan-Ting Chen, Jen-Hsuan Wu, and Wei-Chung Chang
- Subjects
Battery (electricity) ,red phosphorus ,Chemistry ,General Chemical Engineering ,Potassium ,Inorganic chemistry ,General Engineering ,General Physics and Astronomy ,Medicine (miscellaneous) ,chemistry.chemical_element ,wet‐ball milling process ,PHOSPHORUS/POTASSIUM ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Ion ,Anode ,P—C bonding ,Cover Picture ,General Materials Science ,PIB anodes - Abstract
In article number 1801354, Hsing‐Yu Tuan and co‐workers effectively activate red phosphorus as an anode for potassium‐ion batteries with a record‐high specific energy density.
- Published
- 2019
32. Phosphorus-Rich Copper Phosphide Nanowires for Field-Effect Transistors and Lithium-Ion Batteries
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Wei-Chung Chang, Guo-An Li, Hsing-Yu Tuan, and Chiu-Yen Wang
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Electron mobility ,Materials science ,business.industry ,Phosphide ,Inorganic chemistry ,General Engineering ,Nanowire ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Anode ,chemistry.chemical_compound ,Semiconductor ,chemistry ,Optoelectronics ,General Materials Science ,Field-effect transistor ,Lithium ,0210 nano-technology ,business ,Single crystal - Abstract
Phosphorus-rich transition metal phosphide CuP2 nanowires were synthesized with high quality and high yield (∼60%) via the supercritical fluid-liquid-solid (SFLS) growth at 410 °C and 10.2 MPa. The obtained CuP2 nanowires have a high aspect ratio and exhibit a single crystal structure of monoclinic CuP2 without any impurity phase. CuP2 nanowires have progressive improvement for semiconductors and energy storages compared with bulk CuP2. Being utilized for back-gate field effect transistor (FET) measurement, CuP2 nanowires possess a p-type behavior intrinsically with an on/off ratio larger than 10(4) and its single nanowire electrical transport property exhibits a hole mobility of 147 cm(2) V(-1) s(-1), representing the example of a CuP2 transistor. In addition, CuP2 nanowires can serve as an appealing anode material for a lithium-ion battery electrode. The discharge capacity remained at 945 mA h g(-1) after 100 cycles, showing a good capacity retention of 88% based on the first discharge capacity. Even at a high rate of 6 C, the electrode still exhibited an outstanding result with a capacity of ∼600 mA h g(-1). Ex-situ transmission electron microscopy and CV tests demonstrate that the stability of capacity retention and remarkable rate capability of the CuP2 nanowires electrode are attributed to the role of the metal phosphide conversion-type lithium storage mechanism. Finally, CuP2 nanowire anodes and LiFePO4 cathodes were assembled into pouch-type lithium batteries offering a capacity over 60 mA h. The full cell shows high capacity and stable capacity retention and can be used as an energy supply to operate electronic devices such as mobile phones and mini 4WD cars.
- Published
- 2016
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33. Glucosides from the unripe fruit juice of Carica papaya Linn. (Caricaceae) cultivar ‘Red Lady’ with antioxidant activity
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Allan Patrick G. Macabeo, Ma. Alicia M. Aguinaldo, Mary Grace M. Galang, Minoru Isobe, and Wei-Chung Chang
- Subjects
0301 basic medicine ,Isopropyl 5-β-D-glucopyranosyloxy-2-hydroxybenzoate and methyl β-D-glucopyranoside ,Antioxidant ,DPPH ,medicine.medical_treatment ,Medicine (miscellaneous) ,01 natural sciences ,Caricaceae ,03 medical and health sciences ,chemistry.chemical_compound ,DPPH radical ,medicine ,Organic chemistry ,TX341-641 ,Food science ,Scavenging ,Nutrition and Dietetics ,biology ,Carica papaya ,Nutrition. Foods and food supply ,010405 organic chemistry ,biology.organism_classification ,Ascorbic acid ,Red Lady papaya cultivar ,0104 chemical sciences ,030104 developmental biology ,chemistry ,Hydroxyl radical ,Carica ,Isopropyl ,Food Science - Abstract
Natural antioxidants from Carica papaya (‘Red Lady’ cultivar) were investigated. Reversed phase chromatography of the fruit juice gave 12 fractions that were subjected to DPPH and hydroxyl radical scavenging assays. Purification of Cp7 afforded isopropyl 5-β-D-glucopyranosyloxy-2-hydroxybenzoate (1) while the methanol fractions Cp8–10 afforded methyl β-D-glucopyranoside (2). This is the first report on the isolation of these compounds from C.papaya. Compound (1) showed significant DPPH radical scavenging capacity. Compound (2) was an isolate giving 77% DPPH and 81% hydroxyl radical scavenging activities, which are close or equal to the values for the standard ascorbic acid (98% DPPH and 81% hydroxyl radical scavenging activities).
- Published
- 2016
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34. Solution-grown GeO2 nanoparticles with a nearly 100% yield as lithium-ion battery anodes
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Wei-Chung Chang, Guo-An Li, Hsing-Yu Tuan, and Wei-Chin Li
- Subjects
Battery (electricity) ,Materials science ,General Chemical Engineering ,Nanoparticle ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Micelle ,Lithium-ion battery ,0104 chemical sciences ,Anode ,Chemical engineering ,chemistry ,Lithium ,0210 nano-technology ,Germanium oxide - Abstract
Germanium oxide (GeO2) nanoparticles were synthesized with a nearly 100% production yield in a nonionic reverse micelle system at ambient temperature. The procedure is a facile and energy saving strategy for producing germanium oxide nanoparticles with ultra large throughput. As-prepared GeO2 nanoparticles can be directly used as anode materials without any post-treatment or other supplementary additives for lithium ion batteries. GeO2-anodes exhibited good electrochemical performance in terms of both gravimetric and volumetric capacity. The GeO2 anodes have a reversible capacity of approximately 1050 mA h g−1 at a rate of 0.1C, close to its theoretical capacity (1100 mA h g−1), and good rate capability without severe capacity decade. The volumetric capacity of the GeO2 anodes reaches 660 mA h cm−3, which is higher than the performance of commercial graphite anode (370–500 mA h cm−3). Coin type and pouch type full cells assembled for electronic devices applications were also demonstrated. A single battery is shown to power LED array over 120 bulbs with a driving current of 650 mA. Based on the above, the micelle process of GeO2 nanoparticle synthesis provides a possible solution to high-capacity nanoparticles' scalable manufacturing for lithium ion battery applications.
- Published
- 2016
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35. Synthesis of Cu/ZnO core/shell nanocomposites and their use as efficient photocatalysts
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Guo-An Li, Chien-Ming Lai, Shu-Hao Chang, Shu-Chen Lu, Hsing-Yu Tuan, Wei-Chung Chang, and Po-Yuan Yang
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Materials science ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Zinc ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Copper ,0104 chemical sciences ,Nanomaterials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Oleylamine ,Transmission electron microscopy ,Photocatalysis ,General Materials Science ,Selected area diffraction ,0210 nano-technology ,High-resolution transmission electron microscopy - Abstract
The synthesis of a metal/semiconductor (Cu/ZnO) core/shell nanostructure consisting of Cu nanoparticles with an average diameter of 44.4 ± 4.3 nm and coated with a 4.8 ± 0.5 nm-thick layer of ZnO is reported. The Cu/ZnO core/shell nanomaterials were formed by rapidly injecting a mixture of copper(I) chloride, zinc acetate and oleylamine (OLA) solution into a hot OLA solution at 320 °C for 5 min. Both the Cu (core) and ZnO (shell) parts were crystalline according to X-ray diffraction, selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) analyses. The Cu/ZnO core/shell nanomaterials acted as an efficient photocalyst and degraded the pollutant methylene blue, whereas pure Cu nanoparticles did not. The average degradation rate constant of methylene blue by the Cu/ZnO heterostructures was determined to be 1.708 h−1, much higher than those of commercial ZnO (1.628 h−1) and TiO2 (0.307 h−1), showing that the Cu/ZnO core/shell heterostructure is a promising photocatalyst for pollutant degradation.
- Published
- 2016
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36. Phosphorus-sulfur/graphene composites as flexible lithium-sulfur battery cathodes with super high volumetric capacity
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Wei-Chung Chang, Cheng-Chieh Chuang, Hsing-Yu Tuan, and Yi-Yen Hsieh
- Subjects
Materials science ,Graphene ,General Chemical Engineering ,Composite number ,chemistry.chemical_element ,Lithium–sulfur battery ,02 engineering and technology ,General Chemistry ,Current collector ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Sulfur ,Industrial and Manufacturing Engineering ,Cathode ,0104 chemical sciences ,law.invention ,chemistry ,law ,Electrode ,Environmental Chemistry ,Composite material ,0210 nano-technology - Abstract
A phosphorus-sulfur/graphene composite (PS/G composites) cathode via a one-step PS additive reaction at 320 °C is reported to achieve high volumetric capacities with a high sulfur packing density. The PS/G composites are self-supporting, bendable, and compressible, and can be easily compressed into a sheet of binder-free LiS cathode. The PS/G cathode with an extremely high cathode sulfur density of 1.8 g cm−3 (active materials content of 80%) delivers an excellent specific capacity of 959 mA h g−1, an areal capacity of 5.5 mA h cm−2, and exhibits a low capacity fading rate (0.15% per cycle) within 200 cycles (~60% utilization). Consequently, the electrode gives a corresponding high volumetric capacity of 1726 mA h cm−3 (the volume is based on all cathode materials plus current collector). Moreover, flexible devices of Li-S pouch cell using PS/G composites as cathodes shows stable electrochemical characteristics under bending condition, demonstrating their feasibility in commercial batteries.
- Published
- 2020
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37. AgiRPG: An Agile-Based Role-Playing Game Design System
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Chung-Wen Hung, Wei-Chung Chang, and Teng-Wen Chang
- Subjects
Game mechanics ,Non-cooperative game ,Health (social science) ,General Computer Science ,Game design document ,Computer science ,General Mathematics ,General Engineering ,Education ,General Energy ,Game client ,Game design ,Human–computer interaction ,Simultaneous game ,Game Developer ,Video game design ,General Environmental Science - Published
- 2015
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38. Stereochemical Course of Wittig Rearrangements of Dihydropyran Allyl Propargyl Ethers
- Author
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Chin-Hui Yu, Pei-Kang Tsou, Minoru Isobe, Wei-Chung Chang, and Chatchawan Ploysuk
- Subjects
chemistry.chemical_compound ,Deprotonation ,Chemistry ,Dihydropyran ,Stereochemistry ,Organic Chemistry ,Wittig reaction ,Propargyl ,Chirality (chemistry) ,Bond cleavage ,Stereocenter ,Carbanion - Abstract
[2,3]-Wittig rearrangements of sugar-derived dihydropyran allyl propargyl ethers located at the 2- or 4-position have been studied as useful means for extending the carbon chains of the 4- or 2-position with chirality transfer. The stereochemical course of these reactions depends on the following factors: (1) deprotonation of pro-R or pro-S-H, (2) equilibration of the lithiated stereogenic carbanion, (3) conformational inversion during the rearrangement, and (4) concerted [2,3]- or [1,2]-Wittig rearrangement. In some cases, a stepwise mechanism that involves the allyl-C-O bond cleavage is shared as the first step by both the [2,3]- and [1,2]-Wittig rearrangements. The stereochemical courses of the rearrangements are compared among the lithiated reactants to determine the reaction pathways. These mechanisms in the polyoxygenated dihydropyran ring system were further supported by DFT calculations.
- Published
- 2015
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39. Diastereoselective cobalt-assisted Ferrier-type rearrangement to construct chiral alkynyl cyclohexanones
- Author
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Minoru Isobe and Wei-Chung Chang
- Subjects
Steric effects ,Ferrier rearrangement ,Anomer ,chemistry ,Stereochemistry ,Organic Chemistry ,Drug Discovery ,Molecular mechanism ,chemistry.chemical_element ,Stereoselectivity ,Biochemistry ,Medicinal chemistry ,Cobalt - Abstract
Functionalized 1-C-alkynyl sugars are prepared from 2-acetoxy-glucal triacetate. Dicobalt complexes of these sugar acetylenes can stabilize the anomeric carbenium cations, which promote the Ferrier-type rearrangement through the 5,6-dehydro precursors to afford alkynyl cyclohexanones after decomplexation. High stereoselectivity resulted from suitable steric interaction between the C-2 O-protecting group and the alkynyl substituents. Molecular mechanism is discussed.
- Published
- 2014
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40. Model-based optimization for vapor compression refrigeration cycle
- Author
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Lei Zhao, Xu-dong Ding, Wenjian Cai, and Wei-chung Chang
- Subjects
Engineering ,Optimization problem ,business.industry ,Mechanical Engineering ,Cooling load ,Control engineering ,Building and Construction ,Pollution ,Industrial and Manufacturing Engineering ,Nonlinear system ,General Energy ,Control theory ,Component (UML) ,Genetic algorithm ,Electrical and Electronic Engineering ,Vapor-compression refrigeration ,business ,Global optimization ,Operating cost ,Civil and Structural Engineering - Abstract
This paper presents a model-based optimization strategy for vapor compression refrigeration cycle. Through analyzing each component characteristics and interactions within the cycle, the optimization problem is formulated as minimizing the total operating cost of the energy consuming devices subject to the constraints of mechanical limitations, component interactions, environment conditions and cooling load demands. A MGA (modified genetic algorithm) together with a solution strategy for a group of nonlinear equations is proposed to obtain optimal set point under different operating conditions. Simulation studies are conducted to compare the proposed method with traditional on–off control strategy to evaluate its performance. Experiment results of a real practical system are also presented to demonstrate its feasibility.
- Published
- 2013
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41. Decentralized optimization for vapor compression refrigeration cycle
- Author
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Wenjian Cai, Xu-dong Ding, Lei Zhao, and Wei-chung Chang
- Subjects
Engineering ,business.industry ,Computation ,Cooling load ,Energy Engineering and Power Technology ,Energy consumption ,Industrial and Manufacturing Engineering ,Control theory ,Component (UML) ,Genetic algorithm ,Vapor-compression refrigeration ,business ,Global optimization ,Energy (signal processing) - Abstract
This paper presents a model based decentralized optimization method for vapor compression refrigeration cycle (VCC). The overall system optimization problem is formulated and separated into minimizing the energy consumption of three interactive individual subsystems subject to the constraints of hybrid model, mechanical limitations, component interactions, environment conditions and cooling load demands. Decentralized optimization method from game theory is modified and applied to VCC optimization to obtain the Perato optimal solution under different working conditions. Simulation and experiment results comparing with traditional on–off control and genetic algorithm are provided to show the satisfactory prediction accuracy and practical energy saving effect of the proposed method. For the working hours, its computation time is steeply reduced to 1% of global optimization algorithm with consuming only 1.05% more energy consumption.
- Published
- 2013
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42. Spray-Deposited Large-Area Copper Nanowire Transparent Conductive Electrodes and Their Uses for Touch Screen Applications
- Author
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Wei-Chung Chang, Hsing-Yu Tuan, Yen-Chen Chang, Shu-Hao Chang, Yow Lin, Hsun-Chen Chu, and Guo-An Li
- Subjects
Resistive touchscreen ,Materials science ,business.industry ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,0104 chemical sciences ,chemistry ,Electrode ,Transmittance ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Electrical conductor ,Sheet resistance - Abstract
Large-area conducting transparent conducting electrodes (TCEs) were prepared by a fast, scalable, and low-cost spray deposition of copper nanowire (CuNW) dispersions. Thin, long, and pure copper nanowires were obtained via the seed-mediated growth in an organic solvent-based synthesis. The mean length and diameter of nanowires are, respectively, 37.7 μm and 46 nm, corresponding to a high-mean-aspect ratio of 790. These wires were spray-deposited onto a glass substrate to form a nanowire conducting network which function as a TCE. CuNW TCEs exhibit high-transparency and high-conductivity since their relatively long lengths are advantageous in lowering in the sheet resistance. For example, a 2 × 2 cm(2) transparent nanowire electrode exhibits transmittance of T = 90% with a sheet resistance as low as 52.7 Ω sq(-1). Large-area sizes (50 cm(2)) of CuNW TCEs were also prepared by the spray coating method and assembled as resistive touch screens that can be integrated with a variety of devices, including LED lighting array, a computer, electric motors, and audio electronic devices, showing the capability to make diverse sizes and functionalities of CuNW TCEs by the reported method.
- Published
- 2016
43. Development of an accelerated leaching method for incineration bottom ash correlated to toxicity characteristic leaching protocol
- Author
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Shengxuan, Lin, Xuedong, Zhou, Liya, Ge, Sum Huan, Ng, Xiaodong, Zhou, and Victor Wei-Chung, Chang
- Subjects
Sonication ,Time Factors ,Metals, Heavy ,Coal Ash ,Mass Spectrometry ,Environmental Monitoring ,Metalloids - Abstract
Heavy metals and some metalloids are the most significant inorganic contaminants specified in toxicity characteristic leaching procedure (TCLP) in determining the safety of landfills or further utilization. As a consequence, a great deal of efforts had been made on the development of miniaturized analytical devices, such as Microchip Electrophoresis (ME) and μTAS for on-site testing of heavy metals and metalloids to prevent spreading of those pollutants or decrease the reutilization period of waste materials such as incineration bottom ash. However, the bottleneck lied in the long and tedious conventional TCLP that requires 18 h of leaching. Without accelerating the TCLP process, the on-site testing of the waste material leachates was impossible. In this study, therefore, a new accelerated leaching method (ALM) combining ultrasonic assisted leaching with tumbling was developed to reduce the total leaching time from 18 h to 30 min. After leaching, the concentrations of heavy metals and metalloids were determined with ICP-MS or ICP-optical emission spectroscopy. No statistical significance between ALM and TCLP was observed for most heavy metals (i.e., cobalt, manganese, mercury, molybdenum, nickel, silver, strontium, and tin) and metalloids (i.e., arsenic and selenium). For the heavy metals with statistical significance, correlation factors derived between ALM and TCLP were 0.56, 0.20, 0.037, and 0.019 for barium, cadmium, chromium, and lead, respectively. Combined with appropriate analytical techniques (e.g., ME), the ALM can be applied to rapidly prepare the incineration bottom ash samples as well as other environmental samples for on-site determination of heavy metals and metalloids.
- Published
- 2016
44. Applying Evolutionary Computing to Complex Systems Design
- Author
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Wei-Chung Chang, R. Neville, and Alistair Sutcliffe
- Subjects
Human-Computer Interaction ,Control and Systems Engineering ,Computer science ,Formal specification ,Component (UML) ,Systems engineering ,Complex system ,Electrical and Electronic Engineering ,Formal verification ,Requirements analysis ,Software ,Evolutionary computation ,Computer Science Applications - Abstract
Development of an evolutionary computing tool for requirements analysis and optimization of component-based systems is described. The tool assesses scenarios that represent potential designs and their operational behavior, as well as how the designs perform in a range of environmental conditions. Designs are optimized for three objective functions: 1) reliability; 2) performance time; and 3) costs. Use of the tool is illustrated in a systems engineering case study to derive optimal design for a naval command and control system that includes human operator roles as well as technology components.
- Published
- 2007
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45. Time-resolved aerosol and fluorescent bioaerosol concentrations in an air-conditioned and mechanically ventilated office in Singapore
- Author
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JIN ZHOU, Wei-Chung Chang, and Nazaroff, William W.
- Abstract
© 2015 International Society of Indoor Air Quality and Climate. All rights reserved. Using an ultraviolet-light induced fluorescence (UV-LIF) technique, we measured number concentrations of total aerosol particulate matter (tPM) and fluorescent biological aerosol particles (bioPM) (1.0-3.0 µm and 3.0-5.0 µm diameter) in an office and outdoors, sampling with 1-min resolution. The air-conditioning and mechanical ventilation (ACMV) system equipped with high-grade filters was effective in controlling both tPM and bioPM indoors. As expected, removal efficiencies were found to be size dependent. One human subject walking on the carpet was found to be a strong contributor to bioPM, resulting in 2-3 times higher concentration than that outdoors. Compared to the times when the room is vacant, the biological proportion of total airborne particles increased by an order of magnitude during the light walking period. Consequently, indoor-to-outdoor ratios depend on the ACMV operating conditions and on human activities. This pilot study provides preliminary data concerning the bioPM levels in an indoor environment equipped with an ACMV system. Ongoing investigations using this approach promise to improve our understanding of the processes that influence indoor bioaerosol levels and the effectiveness of control alternatives.
- Published
- 2015
46. Bioaccumulation on HVAC filters in university buildings in Singapore
- Author
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Irvan Luhung, Yan Wu, Victor Wei-Chung CHANG, and Nazaroff, William W.
- Subjects
complex mixtures - Abstract
© 2015 International Society of Indoor Air Quality and Climate. All rights reserved. Particle filters are important components of HVAC systems. Biomass accumulation on HVAC filters can potentially have adverse effects on building occupants. The research reported in this paper aims to quantitatively describe the content of biomass on HVAC filters from various indoor office environments in Singapore in relation to key governing processes. In this initial phase, filter samples were collected and analysed using DNA-based methods. The collected DNA was directly extracted from the filters and the final concentration was measured with Qubit and qPCR methods. The DNA concentrations were then related to the cumulative indoor occupancy level. The results show good correlations between bacterial DNA and cumulative occupancy. The proportion of total DNA that belongs to fungal and bacterial species decreases as occupancy level increases, probably because of biomass from other sources such as human skin cells.
- Published
- 2015
47. Characterizing the indoor microbiome in an office in singapore before and after cleaning to address a mold problem
- Author
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Yan Wu, Irvan Luhung, Qingliang Cao, Nazaroff, William W., and Victor Wei-Chung CHANG
- Published
- 2014
48. DNA-based protocol optimization for bioaerosol sampling in an urban tropical environment
- Author
-
Luhung, I., Wu, Y., Nazaroff, W. W., and Victor Wei-Chung CHANG
- Published
- 2014
49. Quality of sleep and quality of life in caregivers of breast cancer patient
- Author
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Tsai-Wang Chang, Edward Wei-Chung Chang, Ying-Ying Tsai, and Chao-Jung Tsao
- Subjects
Gerontology ,Adult ,Male ,Sleep Wake Disorders ,Cross-sectional study ,Quality of sleep ,media_common.quotation_subject ,Health Status ,MEDLINE ,Taiwan ,Experimental and Cognitive Psychology ,Breast Neoplasms ,Pittsburgh Sleep Quality Index ,Breast cancer ,Quality of life ,Risk Factors ,Medicine ,Humans ,Quality (business) ,media_common ,Aged ,business.industry ,Middle Aged ,medicine.disease ,Psychiatry and Mental health ,Cross-Sectional Studies ,Oncology ,Caregivers ,Quality of Life ,Regression Analysis ,Female ,Sleep (system call) ,business ,Sleep - Abstract
Background: Sleep is an important issue for cancer patients and caregivers and poor sleep quality may have deleterious effects on health. This study will examine the correlation between sleep quality and quality of life of breast cancer caregivers. Method: A cross-sectional and correlational design was used to explore the relationship between sleep quality and the quality of life of caregivers. Sixty-one participants were identified by invasive early breast cancer patients, who were diagnosed within the period of 18-month period, as their primary caregivers. The World Health Organization Questionnaire on Quality of Life: BREF-Taiwan version (WHOQOL-BREF-TAIWAN) and the Chinese Pittsburgh Sleep Quality Index (CPSQI) were used to measure the quality of life and sleep quality of caregivers, respectively. Result: Eighty-nine percent of caregivers from this study reported possible sleep difficulties. The scores of CPSQI scores were negatively correlated with the score of every domain of the WHOQOL-BREF-TAIWAN. Discussion: The results suggest that sleep quality may have an impact on several aspects of the quality of life of caregivers. Understanding the correlation between sleep quality and the quality of life of caregivers may assist health professionals in enhancing the sleep quality of caregivers and their ability to care for patients and themselves. Copyright © 2007 John Wiley & Sons, Ltd.
- Published
- 2007
50. Cognitive functioning correlates of self-esteem and health locus of control in schizophrenia
- Author
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Wei-Chung Chang, Jo Yung-Wei Wu, Chien-Shu Wang, and Shu Ping Chuang
- Subjects
self-esteem ,medicine.medical_specialty ,Neuropsychiatric Disease and Treatment ,business.industry ,media_common.quotation_subject ,Self-esteem ,internal health locus of control ,medicine.disease ,external health locus of control ,behavioral disciplines and activities ,cognitive functioning ,schizophrenia ,Psychiatry and Mental health ,Locus of control ,Schizophrenia ,medicine ,In patient ,Cognitive skill ,Psychiatry ,business ,Neurocognitive ,Biological Psychiatry ,Original Research ,media_common - Abstract
Chien-Shu Wang,1 Jo Yung-Wei Wu,2 Wei-Chung Chang,3 Shu-Ping Chuang1 1Department of Psychiatry, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung, Taiwan; 2Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; 3Hsin-Jia Psychotherapy Clinic, Taitung County, Taiwan Aim: The study aimed to investigate the relationship among sociodemographic factors, neurocognitive factors, self-esteem, and health locus of control in patients diagnosed with schizophrenia. We examined the self-esteem, internal health locus of control, and external health locus of control through sociodemographic and neurocognitive factors. Methods: Forty-six schizophrenic patients and 31 healthy residents from the community or hospital were recruited as the control group. All subjects participated in the self-esteem questionnaire, health locus of control questionnaire, and a series of neuropychological measures. Results: Multiple regression analysis revealed that inhibition of attention and external health locus of control were predictors for self-esteem (r=−0.30, P
- Published
- 2013
- Full Text
- View/download PDF
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