34254 research outputs found
Sort by
Synthesis of Biodegradability Polycarbonate Copolymers Using Epoxide and CO2
No full textIn this study focuses on using the epoxy compounds tert-butyl 3,4-epoxybutanoate and benzyl glycidate as monomers to copolymerize with CO2 using binary (salen) Co III X (X = Cl/[PPN]Cl or DNP ), to produce biodegradable polycarbonates. When compared to the references, it was observed that under the same reaction conditions, increasing the monomer concentration did not lead to an increase in the molecular weight of the polycarbonate. The obtained polymer had only about one-third of the expected molecular weight, and the control over the polymerization was not sufficient to achieve a narrow polydispersity index (PDI). Therefore, attempts were made to synthesize a second-generation bifunctional (salen) Co III X catalyst with high selectivity towards epoxy compounds
Wi-Fi-based Passive Radar for Localizing Multiple People and Monitoring Their Vital Signs
No full textThe aim of this study is to develop a passive Doppler radar based on an injection-locked quadrature receiver architecture. The system uses a Wi-Fi access point module as a transmission signal source to detect human vital signs and their distances simultaneously. Due to the presence of amplitude modulation (AM) and phase modulation (PM) components in Wi-Fi signals, the sensing performance of the system is degraded. To improve radar performance, the injection locking technique and dual-channel noise cancellation method proposed by our laboratory are employed to suppress both amplitude and phase modulations, thereby enhancing the quality of Doppler signals and enabling the measurement of respiratory and heartbeat signals.
In order to enable distance measurement with Wi-Fi radar, this study introduces a method based on the concept of frequency-shift keying (FSK) to switch between two different carrier frequencies of Wi-Fi signals using RF switches with compensation for circuit delays. By obtaining the correct phase difference and utilizing digital processing techniques, the phase difference can be converted into distance information accurately. Furthermore, to achieve simultaneous measurements of multiple individuals' vital signs and distances, a 1T6R one-dimensional digital beamforming architecture is utilized. The dual-channel noise cancellation method is employed to suppress Wi-Fi modulation noises, and in conjunction with FSK ranging technology, it allows for angular differentiation between various targets, as well as the simultaneous monitoring of their respiration, heartbeat, and distance information
Ultrasonication Synthesis of 2D Oraganic-Metallic Nanosheets and their Detections of Brain Disease's Biomarkers
No full textThe synthesis of two-dimensional (2D) nanosheet materials has been developed for a period of time. From graphene to boron nitride (BN), transition metal dichalcogenides (TMDs), Mxene, etc., a variety of two-dimensional nanomaterials have been developed successively, which are used in optoelectronics, disease detection, energy, catalysts, etc. Two-dimensional nanomaterials have unique chemical and physical properties. Based on the extremely large specific surface area, two-dimensional nanomaterials have a very large reaction area, thereby improving reaction efficiency. In addition, different two-dimensional nanomaterials also have very good photoelectric or optical effects, and have good mechanical strength, so they have very good prospects in application. In the synthesis of two-dimensional nanomaterials, the ultrasonication probe method is a very promising method. When a specific vibration intensity is applied, the "top-down" and "bottom-up" synthesis mechanisms can be operated at the same time, and the shape and size of the two-dimensional nanomaterials can be further controlled. In addition, the ultrasonication probe method is a simple and low-cost synthesis method, which can achieve the goal of reducing cost, reducing energy consumption, and rapid synthesis, and has very high applicability in the field of synthesis of two-dimensional nanomaterials.
In the first study, 2D nanosheets based on dopamine and molybdenum were synthesized by probe sonication. Amyloid fibrils are a biomarker for psychiatric disorders, and dopamine has the ability to inhibit amyloid fibrils. Dopamine mixed with molybdenum to form two-dimensional nanosheets with a hybrid structure enhanced the ability to inhibit amyloid fibrils. With this phenomenon, the kinetics of inhibition of amyloid fibrils was studied with a fluorometer, and the quantitative detection of amyloid fibrils was performed using a colorimetric method, and a detection limit of 8.01 nM was able to be achieved.
In the second study, 2D nanosheets based on tryptophan and tungsten were synthesized by probe sonication. By combining tryptophan and tungsten, the fluorescence intensity is increased, and it is applied to the detection of epinephrine. Epinephrine is a hormone and neurotransmitter that also acts as a biosensor for certain mental illnesses or problems in the human body. Through the energy transfer fluorescence quenching property of epinephrine, the fluorescence produced by tryptophan-tungsten nanosheets is quenched, and the absorbance colorimetric change of tryptophan-tungsten nanosheets combined with epinephrine is used for quantitative detection of epinephrine, and the detection limits of 0.466 \uce\ubcM and 0.686 \uce\ubcM were respectively achieved
Influences of Mesh Stiffness and Vibration Modes on Spray Characteristics of Piezoelectric Atomizers
No full textThe purpose of this study is to investigate the effect of the vibration mode on the atomization characteristics of a piezoelectric atomizer. By designing piezoelectric atomizers to increase the local stiffness in the mesh, different mode shapes are generated compared to those in the original design. The study analyzes the atomization characteristics by using droplet size and atomization rate as indicators. It aims to analyze the impact of variations in mode shape on atomization performance.
In the design of the piezoelectric atomizer, lead zirconate titanate (PZT) piezoelectric ceramics are chosen as the source of ultrasonic vibration. The stiffness of the mesh is improved through two approaches. The first approach is to design a stainless steel sheet or use adhesive to attach the PC cap to the original piezoelectric atomizer design. The second approach involves replacing the original polyimide (PI) mesh with a metal mesh made of SUS 316 and PdNi, and testing its corrosion resistance against the acidic fluid used in the experiment. Finite element software (COMSOL) is used to perform simulation analysis prior to conducting the experiment. It helps in predicting and evaluating the vibration performance of the piezoelectric atomizer. By utilizing calculated parameters such as impedance, phase, and resonance frequency, one can gain a comprehensive understanding of the response characteristics of the piezoelectric atomizer across different frequencies. These analysis results provide crucial information for selecting the appropriate frequency and driving mode to ensure optimal atomization performance.
The actual measurement demonstrates that the average error between the resonant frequency of nebulizers with different designs and the measured resonant frequency is approximately 1.46%. This indicates that the analysis method employed in this study possesses a certain level of reliability. According to the results of the amplitude measurement, the expected mode shape can be successfully obtained by locally increasing the stiffness of the mesh plate. Combined with the actual atomization situation and the measurement amplitude results, it is speculated that the required amplitude for successful atomization is about 2.3 \uce\ubcm. An empirical formula has been established to calculate the amount of atomization. The results of the particle size measurement show that the piezoelectric atomizer's drive state is controlled by the circuit, making it more sensitive to changes in the particle size distribution. It is possible to achieve a concentrated particle size distribution through the design of the drive circuit
Composite thermal protection coating to prevent ink washout during in-mold decoration process
No full textIn-mold decoration (IMD) is a mass production method that places a pre-made coating layer in the path of injection molding to create perfectly coated parts. While this combine coating and injection molding in one step, IMD coatings can suffer from the coating layer being washed out during the injection molding process. Jin Yadian company\ue2s IMD process suffers from such washout problem when applying a polycarbonate support to a IMD coating. The problem was tackled by modifying the IMD coating in two directions; improving thermal conductivity and improving thermal stability. To improve thermal conductivity, reduced graphene oxide can be added to the coating matrix. To improve thermal stability, polybenzoxazines with high thermal stability can be added to the IMD coating. In addition to improving the qualities of the IMD coating, a characterization method was developed to aid Jin Yadian characterize their IMD coating\ue2s effectiveness. Infrared camera was explored as the convenient solution as it suited a factory\ue2s needs. The infrared camera can detect temperature changes to help evaluate relative heat conductivity between samples
Enhancing the Photothermocatalytic Efficiency of Hg0 and NO in Flue Gases Emitted from Coal-Fired Power Plants with Bi2O3/TiO2 Modified by Reduced Graphene Oxide
No full textAbstract
Mercury (Hg) and nitrogen oxides (NOx) are two main gaseous pollutants in the flue gases of coal-fired power plants and cogeneration boilers. Mercury is characterized by its high volatility, persistent toxicity, long-range transport, and bioaccumulation, posing potential hazards to the ecosystem and human health. In Taiwan, the current technologies employed for mercury removal include wet flue gas desulfurization (WFGD) and electrostatic precipitators (ESP). However, due to low solubility of elemental mercury (Hg0) in water, the removal efficiency is inadequate, which is a major technological bottleneck for coal-fired power plants. Selective catalytic reduction (SCR) is commonly used for NOx control, wherein a catalyst and a reducing agent (such as NH3 or urea) are employed to convert NOx into N2 and H2O. SCR operates optimally at the operating temperatures ranging from 300 to 400\uc2\ub0C, necessitating its placement before ESP and WFGD. However, high concentrations of total particulate matter (TPM) in the flue gas cause masking effect. This effect occurs when the particles interfere with the catalytic process, leading to reduce SCR efficiency. In view of these challenges, the objective of this study is to relocate the SCR system to the downstream of air pollution control devices (APCDS). This approach offers several advantages. Firstly, it allows for lower operating temperatures (100-200\uc2\ub0C). Secondly, by placing the catalyst after high concentrations of particulate matter, it can prevent dust fouling and poisoning effects. Thus, this study aims to develop a high-temperature-tolerant catalyst for the simultaneous removal of Hg0 and NOx.
This research focused on the development of rGO/ Bi2O3/TiO2 photocatalysts with high catalytic oxidation capabilities. This innovative air pollution control technology can be directly applied to the existing SCR systems. This study further investigated the thermal stability and Hg0 oxidation capability of GBT photocatalysts. Initially, different Bi2O3 loading levels in Bi2O3/TiO2 catalysts were tested, and the optimal addition ratio of reduced graphene oxide (rGO) was determined. This study examined the optimal photocatalytic oxidation efficiency of Hg0 at different reaction temperatures. Additionally, it explored the simultaneous removal efficiency of Hg0 and NO, as well as the reaction mechanisms, in the atmosphere of various NO and NH3 concentrations.
The experimental results revealed that GBT photocatalysts were synthesized using a hydrothermal method, with TiO2 predominantly in the form of anatase phase. The BT particles were approximately 2 \uce\ubcm in size and were uniformly dispersed on the surface of folded and layered rGO. XPS analysis indicated the presence of Bi in the forms of Bi0 and Bi3+, and the transformation between these two forms facilitated the adsorption and oxidation of Hg0 and NO. The catalysts contained lattice oxygen (O\uce\ub1) and adsorbed oxygen (O\uce\ub2), with the latter exhibiting higher reactivity and lower binding energy. The 4G3BT catalyst exhibited a high adsorbed oxygen(O\uce\ub2) content up to 14.1%. Raman spectra preseuted the characteristic peaks of Bi2O3, which varied with the doping level. The ID/IG ratio of rGO in this study was 1.25, indicating significant reduction of graphene oxide. PL analysis demonstrated that the addition of Bi2O3 and rGO modification reduced the recombination efficiency of electrons and holes, thereby enhancing the catalytic oxidation efficiency of Hg0. UV-vis analysis indicated a decrease in the bandgap to 2.54 eV after modification, resulting in a redshift phenomenon. EPR spectroscopy revealed that 4G3BT generated the highest amount of \uc2\ub7OH, indicating superior oxidative activity.
The results of Hg0 catalytic oxidation efficiency indicated that the oxidation efficiency decreased with reaction temperature, following the order of \uce\ub7(100\ue2)> \uce\ub7(150\ue2)>\uce\ub7(200\ue2). Among them, BT catalysts prepared with 3% Bi2O3 exhibited better thermal stability. Therefore, the photothermocatalyets was modified to form 4G3BT. In the presence of N2+Hg0+NO atmosphere, low concentrations of NO (300 ppm), it showed a promoting effect. The investigation of different NH3-to-NO concentration ratios revealed that at [NH3]/[NO] = 1:1, the synergistic oxidation-reduction efficiency of Hg0 and NO reached 81% and 90%, respectively, which represented the optimal oxidation-reduction ratio. Using the Langmuir-Hinshelwood (L-H) kinetics model, it was determined that with an increase in reaction temperature, the reaction rate constant (k) increased, while the reaction equilibrium constant (KHg0) decreased. This indicated that higher temperatures reduced the adsorption efficiency of Hg0 over the photocatalyst surface, suggesting that the photocatalytic reaction was primarily controlled by physical adsorption. XPS analysis of 4G3BT after the reaction showed the characteristic peaks of oxidized mercury (HgO), indicating that the photocatalysts facilitated the formation and deposition of HgO over the catalyst surface during the photocatalytic oxidation process.
This innovative technology is a newly developed air pollution control devices (APCD) that can significantly and simultaneously reduce the emissions of Hg0 and NO from flue gases, while effectively enhancing the thermal stability and catalytic oxidation activity of the photocatalysts
Modeling Scandium Based Hydrogen Storage Material in the Presence of Non-Inert Gaseous Species
No full textIn this study, the co-adsorption of O2, H2, and H2O on hydrogen storage materials based on supported scandium atoms has been studied with density functional theory (DFT) calculations and kinetic Monte Carlo (kMC) simulations. This work aims to answer what would happen if a hydrogen storage material accidentally comes in contact with O2 or H2O from the atmosphere. The energetics calculated at the DFT level show that the adsorption energy of oxygen is significantly more exothermic than that of hydrogen and water.
These energetics are used as input for the kMC simulations, which show that single Sc atoms supported on graphene adsorb H2 at 200 K / 300 K and an H2 pressure of 100 bar. If it is due to improper operation, exposing the systems to H2O or O2 will result in the adsorbed hydrogen molecules being replaced. In addition, the simulation has shown that once water is adsorbed on the Sc sites, it can be easily removed under vacuum conditions at 400 K. At variance, O2 is very challenging to remove, no matter with high temperatures or with high H2 pressure at 300 K. This indicates that the big challenge in using supported Sc atom for hydrogen storage is to prevent its contact with O2
Active Distribution Network Planning Considering Uncertainties of Renewable Generation and Load Growth
No full textIntegrated distribution system planning is a specific grid planning method to satisfy load growth and design objectives related to reliability, resilience, safety, and operational efficiency. The installation of distributed energy resources (DER) has transformed the traditional passive distribution network, where power flows from the main transformer to the loads, into an active distribution network that accommodates bidirectional power flows. This study proposes an active distribution network planning model that considers the uncertainties in the load growth prediction and outputs of renewable energy resources for future years. The model adopted in this study divides the energy roles in the distribution network into two players: the distribution system operator (DSO) and the prosumers. Prosumers can play the role of power producers and consumers. Using game theory, the interactions between these two players can be defined as an optimization problem to find the best strategies for each player and satisfy the goal of integrated resource planning. Each player has their respective investment strategies based on the constraints of resources and responsibility. In this study, the prosumer utilizes the Maximin Decision Criterion to select the optimal investment for selling electricity to the DSO. Considering these scenarios and constraints, both players can have a satisfying solution, which leads to the optimal location, equipment type, capacity size, investment time, and electricity price
A Study on the Related Factors of Japan's Frozen Tuna Import
No full textTuna is a natural low-fat source of protein, and the demand for it in health-oriented advanced countries is gradually increasing. Tuna is a food source with high economic value, and the world's production has increased from less than 600,000 tons in 1950 to 6 million tons in 2010. Japan's tuna catch is no longer the largest in the world, but it is still a big consumer of tuna, comprising 20% of the world's tuna. In particular, the consumption of sashimi is large. The consumption of bluefin tuna accounts for 90% of the world market, bigeye tuna accounts for about 31%, albacore tuna accounts for about 27%, and yellowfin tuna accounts for about 11% .The consumption of tuna in japan reach 357,000 tons in 2011.
Currently, the world's tuna catch and tuna trade data are regulated by the International Food and Agriculture Organization (FAO), which was established by the United Nations to combine international efforts to relieve hunger. The goal is to achieve food security and enable people to have enough high-quality food to be active and lead a healthy life. In addition, there are several regional commissions that manage tuna fishery resources through proper regulations, including Indian Ocean Tuna Commission (IOTC), Atlantic Tuna Conservation Commission (ICCAT) and Western and Central Pacific Fisheries Commission (WCPFC) that regulate tuna fishery in Indian Ocean, Atlantic Ocean, and Western and Central Pacific.
The purpose of this study is to compare the data of FAO with IOTC, ICCAT, and WCPFC, in order to understand the respective influences of the catch of the world for Japanese tuna import.
In 2022, the ranking of the price for frozen tuna is southern bluefin tuna > bigeye tuna > yellowfin tuna > albacore, according to the result of calculation, the effective catching in Indian Ocean is most high, the second is Western and Central Pacific Ocean, the lowest is Atlantic Ocean
Application of Modified Biochar Electrode Materials in Supercapacitors and Electrochemical Detection
No full textA supercapacitor is an energy storage device with very high capacity and low internal resistance, which is capable of storing and transferring energy at a much higher rate than batteries due to its energy storage mechanism involving a simple charge at the interface between the electrodes and the electrolyte separate. As an important energy storage device, supercapacitors have attracted much attention due to their small size, light weight, high power density, and long cycle life, and have a wide range of applications. Recycling activated carbon from agricultural waste as an energy storage material, in addition to achieving carbon reduction and green demands, because the activator can adjust the specific surface area, porosity and pore size of activated carbon, so activated carbon is also expected to have high-performance supercapacitors The energy storage capacity makes this research a topic worthy of discussion.
Biomass is renewable organic material from plants and animals.In this study, activated carbon (BC-NaOH) was successfully prepared by using biochar and NaOH as the activator, and compared with activated carbon activated by NaHCO3 and KOH, it has a larger surface area and a good pore structure, BC-NaOH electrode achieved the largest specific capacitance Cb of 315.8 F/g at 0.25 A/g, while BC-NaHCO3 and BC-KOH fabricated using NaHCO3 and KOH showed smaller Cb values of 165.9 and 151.7 F/g. Using BC-NaOH test, the maximum energy density at 2500 W/kg was 9.3 Wh/kg, and the Cb retention was 96.8\uc2\ub1 1.28 % after 2500 charge/discharge cycles. The synthesis of activated carbon has successfully opened up a new blueprint for utilizing waste to produce highly efficient energy storage materials, which is expected to further enhance the energy storage capacity of waste-derived activated carbon by improving the activation process in the near future.
In addition, this experiment uses biochar and KOH as activators to prepare activated carbon (BC-KOH). In the detection experiment of H2O2 by cyclic voltammetry, a set of linear range of 2-400 \uce\ubcM can be obtained, and the detection limit is about 3.762 \uc2\ub5M (S/N=3), which is lower than the (Federal Food and Drug Administration, FDA) limit of 15 \uc2\ub5M for H2O2 remaining in food packages immersed in distilled water. This method has low material cost , the manufacturing process is simple and the material is sustainable