National Taiwan University of Science and Technology

About: National Taiwan University of Science and Technology is a education organization based out in Taipei, Taipei, Taiwan. It is known for research contribution in the topics: Fuzzy logic & Control theory. The organization has 16288 authors who have published 21577 publications receiving 426294 citations. The organization is also known as: Taiwan Tech & Taiwantech.

Active-Clamping ZVS Flyback Converter Employing Two Transformers

Abstract: This paper presents a two-transformer active-clamping zero-voltage-switching (ZVS) flyback converter, which is mainly composed of two active-clamping flyback converters. By utilizing two separate transformers, the proposed converter allows a low-profile design to be readily implemented while retaining the merits of a conventional single-transformer topology. The presented two-transformer active-clamping ZVS flyback converter can approximately share the total load current between two secondaries. Therefore, the transformer copper loss and the rectifier diode conduction loss can be decreased. Detailed analysis and design of this new two-transformer active-clamping ZVS flyback converter are described. Experimental results are recorded for a prototype converter with an ac input voltage ranging from 85 to 135 V, an output voltage of 24 V and an output current of 8 A, operating at a switching frequency of 180 kHz.

Ultrathin TiO2-coated MWCNTs with excellent conductivity and SMSI nature as Pt catalyst support for oxygen reduction reaction in PEMFCs

Abstract: The sluggish kinetics of the oxygen reduction reaction (ORR), the instability of platinum on the carbon support, and carbon corrosion are still critical issues affecting the activity and long-term durability of polymer electrolyte membrane fuel cells. An ideal solution would be to modify the catalytic supports to enhance the durability and performance of supported catalysts. Here we have synthesized multiwalled carbon nanotube (MWCNT) supported ultrathin TiO2 films (MWCNT@UT-TiO2) using a simple modified sol–gel method. Our approach takes advantage of the strong metal support interactions (SMSIs) between the MWCNT@UT-TiO2 support and platinum nanoparticles, which results in a decrease of the d-band vacancy of platinum due to electron transfer from the support, thereby enhancing the performance of the supported catalysts. Our results revealed that Pt–MWCNT@UT-TiO2 has better catalytic activity and durability compared to Pt–MWCNT and Pt–C with equivalent Pt loadings.

Application of paramagnetic graphene quantum dots as a platform for simultaneous dual-modality bioimaging and tumor-targeted drug delivery

Abstract: Here, we report the development of a multifunctional nanocarrier consisting of paramagnetic graphene quantum dots (GQDs), folate, and doxorubicin (Dox), used as delivery vehicles, a targeting ligand, and a chemotherapeutic drug, respectively. The paramagnetic GQDs, named folate–GdGQDs, were successfully prepared by covalently conjugating diethylenetriaminepentaacetic acid gadolinium and folic acid onto the surface of GQDs. The resultant folate–GdGQDs, which showed a longitudinal relaxivity r1 of 11.49 mM−1 s−1, greatly enhanced the brightness of the T1-weighted magnetic resonance (MR) images, indicating their potential for use as positive contrast agents for MR imaging (MRI). The feasibility of utilizing the folate–GdGQDs with strong luminescence emissions for targeted imaging of HeLa cells was also evaluated. An in vitro cell (HeLa and HepG2 cells) viability assay and in vivo evaluation of toxicity to the embryonic development of zebrafish showed that these folate–GdGQDs exhibited negligible cytotoxicity and excellent biocompatibility within the given range of concentrations. More importantly, strong therapeutic activity was achieved by loading Dox onto the surfaces of folate–GdGQDs through π–π stacking and hydrophobic interactions, leading to the formation of folate–GdGQD/Dox multifunctional nanocarriers. Approximately 80% of the loaded Dox was released from the folate–GdGQD/Dox nanocarriers under mild acidic conditions (pH 5.0), whereas only 20% of Dox was released at pH 7.0 after 48 h. Furthermore, these multifunctional nanocarriers could efficiently induce an inhibitory effect on HeLa cells, as confirmed by an in vitro cytotoxicity assay. The combined flow cytometry analysis and confocal laser scanning microscopic observation showed that these nanocarriers were efficiently taken up by the cancer cells overexpressing folate receptors. Taken together, these results suggested that the multifunctional nanocarriers could be used as promising targeted drug delivery vehicles for the diagnosis and image-guided chemotherapy of various cancers.