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.

Low Dielectric Constant and High Organosolubility of Novel Polyimide Derived from Unsymmetric 1,4-Bis(4-aminophenoxy)-2,6-di-tert-butylbenzene

Abstract: A series of new polyimides (PIs) containing tert-butyl side groups were synthesized via a polycondensation of 1,4-bis(4-aminophenoxy)-2,6-di-tert-butylbenzene (4) with various aromatic tetracarboxylic dianhydrides. The introduction of the asymmetric di-tert-butyl groups is an effective way to increase the interchain distance and decrease in the intermolecular force and packing ability of the resulting polymers. Thus, this novel PIs exhibit a low dielectric constant (2.74−2.92), low moisture absorption (0.32−1.53%), excellent solubility, and high glass transition temperature (276−398 °C). The PIs derived from the very rigid pyromellitic dianhydride (PMDA) were soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, chloroform, tetrahydrofuran, and cyclohexanone. The crystal structure of 1,4-bis(4-phthalimidophenoxy)-2,5-di-tert-butylbenzene indicates that the symmetric compound leads to the strong intermolecular interaction and good packing ability. In the 1H spectrum of the diamine 4, the protons of 4-a...

Dynamic properties of mixed nanoparticle/surfactant adsorption layers

Abstract: The adsorption films of silica nanoparticles modified by a cationic surfactant (cetyltrimethylammonium bromide, CTAB) at the air–water interface were investigated by the dilational surface rheology and optical methods. Special attention was paid to the slow changes of surface properties with the surface age. The surface tension and dynamic dilational surface elasticity were measured as a function of CTAB concentration. The whole surfactant concentration range can be divided into four regions characterized by different surface rheological behavior. Depending on the CTAB concentration, the surface elasticity close to the equilibrium may reach extremely high values (∼1000 mN m−1) and strongly depends on the applied surface strain. This occurs at surfactant concentrations below the region where the dispersion becomes turbid, indicating particle aggregation in the bulk. The Brewster angle microscopy and ellipsometry show that the adsorption layer becomes fragile and inhomogeneous in this region.

Inverse halftoning algorithm using edge-based lookup table approach

Abstract: The inverse halftoning algorithm is used to reconstruct a gray image from an input halftone image Based on the recently published lookup table (LUT) technique, this paper presents a novel edge-based LUT method for inverse halftoning which improves the quality of the reconstructed gray image The proposed method first uses the LUT-based inverse halftoning method as a preprocessing step to transform the given halftone image to a base gray image, and then the edges are extracted and classified from the base gray image According to these classified edges, a novel edge-based LUT is built up to reconstruct the gray image Based on a set of 30 real training images with both low- and high-frequency contents, experimental results demonstrated that the proposed method achieves a better image quality when compared to the currently published two methods, by Chang et al and Mes$80e and Vaidyanathan

Quantum confinement effect in diamond nanocrystals studied by X-Ray-absorption spectroscopy

Abstract: This study measures the x-ray-absorption spectra of a series of nanodiamond thin films with grain diameters ranging from 3.5 nm to $5\ensuremath{\mu}\mathrm{m}$ at the C $K$-edge using the sample drain current mode at room temperature. Resonance peaks resembling the C $1s$ core exciton are observed. The exciton state and conduction band edge are found to shift to higher energies with the decrease of the grain size indicative of the presence of the quantum confinement effect.