Search

In three-phase ac/dc power applications, the dc-link voltage of the Vienna rectifier can function as a dual-output independent voltage source. This enables it to fulfill various output voltage requirements for dual-loaded dc-link buses. These requirements may arise owing to different charging rates applied to the dual loads or other factors that cause unbalanced voltage at the output capacitor terminals. To address these scenarios, this article introduces a novel voltage judgment component injection scheme (VJCIS) for Vienna rectifiers. The VJCIS considers the effective reduction of input current distortion and neutral point voltage oscillation in both balanced and unbalanced capacitor voltages. These improvements enhance the dc output performance, allowing the simultaneous control of balanced and unbalanced output voltages to satisfy the requirements of dual-port and parallel charging applications. The proposed VJCIS method only requires the identification of specific continuous intervals and clamping intervals using the input voltage signal and reference voltage to enhance the dc output voltage performance and eliminate zero crossing distortion in the input current. Experimental results in the practical implementation of a 2.4-kW Vienna rectifier confirm the effectiveness and correctness of the proposed method.

In skeletal muscles, calorie restriction (CR) preserves muscle mass in middle-aged rats but not younger rats. The underlying mechanisms for this age-specific response are unknown. Skeletal muscle mass depends on several factors, with protein synthesis and degradation playing major roles. Therefore, the purpose of this study was to investigate whether CR affects younger and older animals differently on mTOR signaling and ubiquitin-proteasome pathway (UPP). Four-, 8-, and 16-month-old rats, with or without 40% CR for a duration of 14 weeks, were sacrificed after an overnight fasting. Total protein content and the phosphorylation level of AKT, mTOR, S6K, and 4EBP1 and protein content of key markers in the UPP (FOXO3a, atrogin, MuRF1, ubiquitinated proteins, proteasome subunits alpha 7 and beta 5) were determined. Unlike younger rats, CR decreased the content of phosphorylated mTOR, S6K, phosphorylated S6K, FOXO3a, and ubiquitinated proteins in middle-aged rats. In conclusion, CR-induced reduction of content/ phosphorylation levels of key proteins in mTOR signaling and the UPP occurred in the middle-aged rats but not younger rats. The age-dependent effects of CR on mTOR signaling and the UPP indirectly explained the age-related effects of CR on muscle mass of animals.

Single-molecule tracking is a powerful method to study molecular dynamics in living systems including biological membranes. High-resolution single-molecule tracking requires a bright and stable signal, which has typically been facilitated by nanoparticles due to their superb optical properties. However, there are concerns about using a nanoparticle to label a single molecule because of its relatively large size and the possibility of cross-linking multiple target molecules, both of which could affect the original molecular dynamics. In this work, using various labeling schemes, we investigate the effects using nanoparticles to measure the diffusion of single-membrane molecules. By conjugating a low density of streptavidin (sAv) to gold nanoparticles (AuNPs) of different sizes (10, 15, 20, 30, and 40 nm), we isolate and quantify the effect of the particle size on the diffusion of biotinylated lipids in supported lipid bilayers (SLBs). We find that single sAv tends to cross-link two biotinylated lipids, leading to a much slower diffusion in SLBs. We further demonstrate a simple and robust strategy for the monovalent and oriented labeling of a single lipid molecule with a AuNP by using naturally dimeric rhizavidin (rAv) as a bridge, thus connecting the biotinylated nanoparticle surface and biotinylated target molecule. The rAv–AuNP conjugate demonstrates fast and free diffusion in SLBs (2–3 μm2/s for rAv–AuNP sizes of 10–40 nm), which is comparable to the diffusion of dye-labeled lipids, indicating that the adverse size and cross-linking effects are successfully avoided. We also note that the diffusion of dye-labeled lipids critically depends on the choice of dye, which could report different diffusion coefficients by about 20% (2.2 μm2/s of ATTO647N and 2.6 μm2/s of ATTO532). By comparing the diffusion of the uniformly and randomly oriented labeling of a single lipid molecule with a AuNP, we conclude that oriented labeling is favorable for measuring the diffusion of single-membrane molecules. Our work shows that the measured diffusion of the membrane molecule is highly sensitive to the molecular design of the cross-linker for labeling. The demonstrated approach of monovalent and oriented AuNP labeling provides the opportunity to study single-molecule membrane dynamics at much higher spatiotemporal resolutions and, most importantly, without labeling artifacts.

Native cell-membrane-derived supported lipid bilayers (SLBs) are an emerging platform with broad applications ranging from fundamental research to next-generation biosensors. Central to the success of the platform is the proper accommodation of membrane proteins so that their dynamics and functions are preserved. Polymer cushions have been commonly employed to avoid direct contact between the bilayer membrane and the supporting substrate, and thus, the mobility of the transmembrane proteins is maintained. However, little is known about how the polymer cushion affects the absolute mobility of membrane molecules. Here, we characterized the dynamics of single membrane proteins in polymer-cushioned lipid bilayers derived from cell plasma membranes and investigated the effects of polymer length. Three membrane proteins with distinct structures, i.e., a GPI-anchored protein, single-pass transmembrane protein CD98 heavy chain, and seven-pass transmembrane protein SSTR3, were fused with green fluorescent protein (GFP), and their dynamics were measured by fluorescent single-molecule tracking. An automated data acquisition was implemented to study the effects of PEG polymer length on protein dynamics with large statistics. Our data showed that increasing the PEG polymer length (molecular weight from 1000 to 5000) enhanced the mobile fraction of the membrane proteins. Moreover, the diffusion coefficients of transmembrane proteins were augmented with the polymer length, whereas the diffusion coefficient of the GPI-anchored protein remained almost identical for different polymer lengths. Importantly, the diffusion coefficients of the three membrane proteins became identical (2.5 μm2/s approximately) for the cushioned membrane with the longest polymer length (molecular weight of 5000), indicating that at the microscopic length scale, the SLBs were fully suspended from the substrate by the polymer cushion. Transient confinements were observed for all three proteins, and increasing the polymer length reduced the tendency of transient confinement. The measured dynamics of membrane proteins were found to be nearly unchanged after the depletion of cholesterol, suggesting that the observed immobilization and transient confinement were not due to cholesterol-enriched membrane nanodomains (lipid rafts). Our single-molecule dynamics elucidate the biophysical properties of polymer-cushioned plasma membrane bilayers that are potentially useful for the future developments of membrane-based biosensors and analytical assays.

The predominance for dye-sensitized solar cell (DSSC) is its application in low illumination. However, there are only a few studies to investigate the performance of DSSC under low illumination. In this study, we investigated DSSC's effect on photovoltaic performance under low illumination. The photoelectrode of DSSC is based on titanium dioxide–reduced graphene oxide (RGO)–indium gallium zinc oxide (IGZO) composited photoelectrode, which was fabricated through the hydro-thermal method, spin coating, and sputtering. According to our experiments, the improvement in photovoltaic conversion efficiency of DSSC achieved 69.57%, after introducing IGZO and RGO into the photoelectrode. Moreover, the enhancement of photovoltaic conversion efficiency under low illumination is due to the decrease in dark reaction, and the amount of the current is small under low illumination. Thus, in order to increase the photovoltaic conversion efficiency under low illumination, it is crucial to decrease the back reaction or dark reaction.

In this study, titanium dioxide (TiO2) colloid was deposited on the fluorine-doped tin oxide substrate by a spin coating method and blade coating method. The characteristics of indium gallium zinc oxide (IGZO) are uniform porous structure, lower reverse recombination, high optical transparency, and good mobility. Composite of an IGZO/TiO2 film was fabricated by sputtering IGZO on the TiO2 film to form a photoelectrode. The reduced graphene oxide (rGO) has high electrocatalysis activity and excellent electron conduction. Besides, the rGO can be applied to the counter electrode of a dye-sensitized solar cell (DSSC). The IGZO/TiO2 photoelectrode with a platinum (Pt) counter electrode exhibited optimal photovoltaic conversion efficiency ( η), and η increased 21% compared with a pure TiO2 photoelectrode. η of the IGZO/TiO2 photoelectrode and rGO/Pt counter electrode exhibited optimal efficiency, which was comparable with a TiO2 photoelectrode with the Pt counter electrode under the same condition. In our research, electrochemical impedance spectroscopy was used to analyze the interface resistance between internal components, which could confirm recombination of electrons and electrical conductivity. The rGO/Pt counter electrode demonstrated low resistance between electrolyte and counter electrode, whose resistance was similar to the pure Pt counter electrode.

Objective To determine the effects and potential synergy of resistance training (RT), Huang Qi(HQ) herbal supplementation, and electroacupuncture (EA) on skeletal muscle mass, contractile properties, and components of the insulin signalling pathway in healthy Sprague Dawley rats.Methods Female Sprague Dawley rats were randomly assigned to one of five groups (n=8 each): control (CON), RT only, RT with EA (RT-EA), RT with HQ (RT-HQ), and RT combined with both EA and HQ (RT-EA-HQ). RT was performed using ladder climbing every other day for 8 weeks. Sparse-wave EA was applied for 15 min/day, 3 times/week for 8 weeks. HQ supplementation was provided via oral gavage daily for 8 weeks.Results RT significantly increased the muscle mass of the flexor hallucis longus (FHL) compared to CON. The isometric twitch and tetanic tension of the FHL in the RT-EA, RT-HQ, and RT-EA-HQ groups were significantly higher compared to CON and RT groups. RT-EA treatment (with or without HQ) significantly increased GLUT4 protein concentration but had no impact on Akt-2.Conclusions EA appears to be an effective treatment modality for increasing muscle mass and function when combined with RT. RT-EA may also be an effective method for improving glucose tolerance as a result of increases in GLUT4 protein concentration.

In this study, the titanium dioxide (TiO2) photoelectrode of a dye-sensitized solar cell (DSSC) was fabricated into a double-layer structure, which was made up of a TiO2/graphene/magnetic bead layer and a TiO2 layer by the spin coating method and electrophoretic deposition. The effects of graphene and magnetic bead for photovoltaic performances of the DSSC were investigated by X-ray diffraction, solar simulator, ultra-violet (UV)-visible spectrometer, and electrochemical impedance spectroscopy. According to the experimental results, graphene had the higher specific surface area to improve the dye loading of the DSSC and magnetic bead used its ability for dispersion and charge transfer to enhance the electron transportation in the DSSC, which made the photovoltaic conversion efficiency of DSSC achieve 5.70%. Moreover, DSSC with incorporation of graphene and magnetic bead was combined with electrochemical capacitor, which had the specific capacitance of 4.15 F/g to store energy from DSSC. Then, the electricity stored from electrochemical capacitor was used to drive the light-emitting diode (LED) for work.

Graphene/TiO2 composite films were deposited on fluorine-doped SnO2-coated conductive substrates by spin coating acting as photoelectrodes of dye-sensitized solar cells. The graphene/TiO2 composite films were characterized by scanning electronic microscopy, an X-ray diffractometer, a UV-visible spectrometer, and electrochemical impedance spectroscopy. Nyquist plots showed the decrease of impedance, in which electron transport rate was promoted. The photovoltaic properties showed that the incorporation of graphene could increase the short-circuit current density and photoelectric conversion efficiency. However, an excessive incorporation of graphene led to the enhancement of charge recombination and the reduction of photoelectric conversion efficiency. The graphene/TiO2 composite film with 1.5-mL graphene oxide solution obtained the optimal photoelectric conversion efficiency of 5.26%.

The lifeworlds of children incorporate home, school and community locations. They are different environments and each has different contexts and goals. In Taiwan, while school is more focused on an overt exchange of teaching and learning, home is more informal and generally characterized by unstructured contexts and parents' attention that encourages and enhances their children's learning with practical knowledge. Consequently, while literacy is taught in school via a well-planned curriculum, at home it is expected to happen via everyday communications and family activities that promote a close parent-child relationship. This ethnographic study was designed to consider emerging literacy practices in two main venues of kindergarten children's life (school and home) to get a greater understanding of how early literacy is evident in Taiwan. In addition, patterns and practices of children's literacy learning in both urban and suburban areas of Taiwan are scrutinized and analyzed to provide a rationale for early literacy learning and teaching in a time of governmental mandates and global literacy efforts.

A laboratory-made conducting polymer reference electrode (CPRE) was developed using polypyrrole coated onto indium tin oxide by the electroplating technique and used as the miniaturized reference electrode (RE) for a ruthenium dioxide (RuO2)ion-selective electrode device in electrochemical hydrogen ion measurements. Ruthenium dioxide thin films were deposited by a radio frequency sputtering method, and the sensing characteristics of RuO2were measured with a CPRE and an Ag/AgCl RE. Subsequently, the selectivity coefficients (K+, Na+, Ca2+, Mg2+, and NH4+) of the ruthenium dioxide thin film with the CPRE were investigated. Furthermore, we also compared the sensing characteristics (such as: pH sensitivity, drift rate, hysteresis width, and response time) of the RuO2thin-film pH electrode with a commercial Ag/AgCl RE and the laboratory-made CPRE. The experimental results demonstrated that the sensing characteristics of the RuO2pH electrode measured with the laboratory-made CPRE are superior to the Ag/AgCl RE, and the size of the CPRE can be efficiently miniaturized compared to a commercial Ag/AgCl RE.