Chien-Hsin Yang

Modified Polyanilines via Electrochemical Copolymerization of Aniline and para‐phenylenediamine Derivatives

Copolymerization of 2,5-diaminobenzenesulfonic acid (DABSA) and para-phenylenediamine (PPDA), respectively, with aniline (AN) was electrochemically performed by cyclic voltammetry on IrO 2 -coated electrodes in 1 M HCl. The copolymerization rate strongly depends on the amount of DABSA/PPDA in the comonomer feed. The composition analysis results indicate that the cross-linking and branching reactions occur simultaneously during copolymerization at the fraction of DABSA larger than 0.206 in DABSA-AN comonomer feed. The above-mentioned two reactions exist in the PPDA-AN copolymerization system at PPDA levels of 0.102 in comonomer feed. From x-ray photoelectron spectroscopy results, the C 1s lines show that the net charge residing on the carbon atoms is affected neither by reaction time (cycle number) nor by the DABSA/PPDA fraction in the feed. The N 1s lines show that the second component peak corresonding to an amine site at 400.4 eV is more dominant for both DABSA and PPDA-modified polyanilines. The composite film of DABSA/PPDA-AN copolymer with waterborne polyurethane was prepared, and its conductivity measured to compare the effect of DABSA/PPDA in the comonomer feed. Stability testing shows DABSA-AN copolymer film more stable than PPDA-AN copolymer film. Electrochemical response of the modified polyaniline films to dissolved hydroquinone and Fe(CN) 4- 6 was also examined

Hypochlorite generation on Ru–Pt binary oxide for treatment of dye wastewater

Ruthenium–platinum binary oxides [(Ru + Pt)Ox] were coated on titanium substrates by thermal decomposition. The surface morphologies and elemental analyses of these electrodes were examined by means of scanning electron microscopy. The electrochemical behaviour was characterized by cyclic voltammetry (CV) and linear scanning voltammetry (LSV). The effects of electrolyte conditions on the current efficiency (CE) of hypochlorite production on binary (Ru + Pt)Ox electrodes and the treatment of a high salt-containing dye wastewater using this hypochlorite were also investigated. The highest CE for hypochlorite production occurred on the RP1 (20 mol% Pt in precursor) electrode. The major factors influencing CE for hypochlorite production were the electrolyte flow rate, current density and chloride ion (C1−) concentration. The RP1 electrode exhibited the best removal of organics and chromophoric groups in the dye wastewater. On this electrode, better removal of organics and chromophoric groups was obtained at 300 mA cm−2. The colour of black–red dye wastewater became light yellow when a charge of 13.2 A h was passed while the COD of the wastewater decreased from 10 500 to 1250 mg L−1.

Multiphase CT Angiography versus Single-Phase CT Angiography: Comparison of Image Quality and Radiation Dose

BACKGROUND AND PURPOSE: Conventional CT angiography (CTA) is acquired during only a short interval in the arterial phase, which limits its ability to evaluate the cerebral circulation. Our aim was to compare the image quality and radiation dose of conventional single-phase CTA (SP-CTA) with a multiphase CTA (MP-CTA) algorithm reconstructed from a perfusion CT (PCT) dataset. MATERIALS AND METHODS: Fifty consecutive patients undergoing head CTA and PCT in 1 examination were enrolled. The PCT dataset was obtained with 40.0-mm-detector coverage, 5.0-mm axial thickness, 80 kilovolt peak (kVp), 180 mA, and 30 mL of contrast medium. MP-CTA was reconstructed from the same PCT dataset with an axial thickness of 0.625 mm by using a new axial reconstruction algorithm. A conventional SP-CTA dataset was obtained with 0.625-mm axial thickness, 120 kVp, 350 mA, and 60 mL of contrast medium. We compared image quality, vascular enhancement, and radiation dose. RESULTS: SP-CTA and MP-CTA of 50 patients (male/female ratio, 31/19; mean age, 59.25 years) were analyzed. MP-CTA was significantly better than SP-CTA in vascular enhancement (P = .002), in the absence of venous contamination (P = .006), and was significantly higher in image noise (P < .001). MP-CTA used less contrast medium than SP-CTA and could demonstrate hemodynamic information. The effective dose of MP-CTA was 5.73 mSv, which was equal to that in conventional PCT, and it was 3.57 mSv in SP-CTA. CONCLUSION: It is feasible that MP-CTA may provide both CTA and PCT results. Compared with SP-CTA, MP-CTA provides comparable image quality, better vascular enhancement, hemodynamic information, and more noise with less detail visibility with a lower tube voltage. The radiation dose of MP-CTA is higher than that of SP-CTA, but the dose can be reduced by altering the sampling interval.

Ionic conductivity of polymer electrolytes derived from various diisocyanate-based waterborne polyurethanes

Abstract Various diisocyanate-based waterborne polyurethanes (WPU) were synthesized by polyaddition of poly(propylene glycol) (PPG) and dimethylol propionic acid (DMPA) with various diisocyanates ((4,4′-methylenebis(phenyl isocyanate) (MDI), 4,4′-methylenebis(cyclohexyl isocyanate)(H12MDI), isophorone diisocyanate (IPDI), and toluene diisocyanate(TDI)) via our modified acetone process. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and impedance spectroscopy (IS) were utilized to monitor the phase change and the conductivity of the WPU-based electrolytes with the doped lithium perchlorate (LiClO4) concentration. The soft segment Tg increases with increasing LiClO4 from the examination of DSC. Significant changes occur in the FTIR spectrum of the various diisocyanate-based WPUs with adding LiClO4, indicating that different interactions with the lithium cation within the hard segment and between the hard and soft phases occur. The result reflects that the phase separation of aromatic diisocyanate-based WPU is more significant than that of aliphatic one in the addition of salts. IS results indicate that there exists the different effect of the added lithium salt on conductivity for aromatic/aliphatic diisocyanate-based WPU electrolytes.

Mixture design approaches to IPDI-H6XDI-XDI ternary diisocyanate-based waterborne polyurethanes

Abstract A systematic modelling analysis for polyaddition of poly(butylene glycol adipate) [PBA] to isophorone diisocyanate (IPDI), xylene diisocyanate (XDI) and hydrogenated xylene diisocyanate (H6XDI) ternary diisocyanate-based waterborne polyurethane (WPU) synthesized by a modified acetone process was performed. Using a mixture of experimental designs, empirical models are fitted and plotted as contour diagrams, which facilitate revealing the synergistic/antagonistic effects between the mixed diisocyanates. The results indicate that each component demonstrates different performances in either binary (IPDI–XDI, XDI–H6XDI and IPDI–H6XDI) or ternary (IPDI–XDI–H6XDI) systems with the IPDI-based WPU, which possesses the highest tensile strength. The largest ultimate elongation occurs at 1 3 IPDI/ 1 3 H6XDI/ 1 3 XDI ternary diisocyanate-mixed WPU. Particle size analysis shows that the larger particles are obtained in the dispersion of IPDI–XDI binary WPU. Differential scanning calorimetry (DSC) results show that PBA polyol and its converted WPU show doublet melting behaviour. A plot of 1/TmL (lower melting temperature) against −lnXIPDI (mole fraction of IPDI in mixed diisocyanates) is approximately linear, indicating that the hard segments are randomly distributed along the molecular chain. Wide angle X-ray diffraction (XRD) and polarized microscopy (POM) on these WPU films were also examined.

Synthesis of CdSe-Poly(N-vinylcarbazole) Nanocomposite by Atom Transfer Radical Polymerization for Potential Optoelectronic Applications.

A hybrid inorganic-polymer nanocomposite using CdSe nanocrystals with high electron mobility has been successfully synthesized by atom transfer radical polymerization (ATRP). First the hydroxyl-coated CdSe nanoparticles (i.e., CdSe-OH) were prepared via a wet chemical route. A polymerization initiator was then prepared for ATRP of N-vinylcarbazole. FT-IR, (1) H NMR, and XRD analyses confirmed the successful synthesis of CdSe-poly(N-vinylcarbazole) (PVK) nanohybrid. UV-Vis spectra and photoluminescence data revealed that grafting of PVK onto the surface of CdSe nanocrystals would reduce the band gap of PVK and cause the red shift of emission peak. TEM and SEM micrographs exhibited CdSe nanoparticles that were well-coated with PVK polymer.

Effects of pH on electrocatalytic activity of functionalized carbon nanotubes

In this study, we modified carbon nanotubes (CNTs) by grafting with poly(ethylene glycol) (PEG) using the “grafting to” method. The PEG-grafted CNT (CNT-g-PEG) was cast on indium tin oxide (ITO) electrode to investigate the electrocatalytic activity of CNT to the redox reactions of the Fe(CN)63−/4−as a probe using cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of CNT was correlated with CNT dispersion in the cast film on ITO as a function of pH of aqueous solution from which the film was cast. The CNT dispersions in aqueous solutions of different pH and in the cast films were examined by visual observation and zeta potential, scanning electron microscopy and transmission electron microscopy, respectively. At a pH in the range of 3–11 at which ITO electrode was modified, two functionalized CNT (fCNT and CNT-g-PEG) were both found to electrocatalyze the redox reactions of the Fe(CN)63−/4−probe and the PEG grafts in CNT-g-PEG could help CNT adhere to the electrode to obtain durable modified electrode. The more uniform CNT dispersions in aqueous solutions and in the cast films appeared to have greater electrocatalytic acitivity.

Dual donor–π–acceptor type organic dyes for efficient dye-sensitized solar cells

A series of novel triphenylamine (TPA)-based dyes that use double linkers between the electron donor and the electron acceptor are synthesized, characterized, and applied as photosensitizers for dye-sensitized solar cells. The dyes contain N-methylpyrrole (NMP) (MTPA-2 dye) and styrene (St) (STPA-2 dye), respectively, linkers on TPA. These linkers are expected to generate effective π-conjugation forming donor–π–acceptor (D–π–A) links. The photovoltaic performance of the dyes depends on the linker type. For the dual-St-π-linked dye, the charge transfer from the excited dye molecules to the conduction band of TiO2 is improved, making the efficiency of the corresponding devices higher than those of dye-based devices with NMP linkers and no linkers. The device with the dye bearing positions of C3 and C4 on NMP linkers has the lowest conjugation effect and efficiency. In particular, the STPA-2 dye shows a broad incident-photon-to-current conversion efficiency response with a signal of up to 700 nm, covering most of the ultraviolet-visible light region. Device efficiencies of 5.43% and 7.56% for dye-sensitized devices using the STPA-2 dye and the cis-RuL2(NCS)2 (N3) dye, respectively, were fabricated using the same method and measured under AM 1.5 irradiation.

CT Angiography Findings in Carotid Blowout Syndrome and Its Role as a Predictor of 1-Year Survival

BACKGROUND AND PURPOSE: Carotid blowout is a serious late complication of prior treatment of advanced head and neck cancer. We evaluate the efficacy of CTA in the diagnosis of impending carotid blowout syndrome in patients with head and neck cancer, and its capability to predict clinical outcome. MATERIALS AND METHODS: The clinical data of 29 patients with impending carotid blowout who underwent CTA were collected and analyzed. Imaging signs included tissue necrosis, exposed artery, viable perivascular tumor, pseudoaneurysm, and contrast extravasation. DSA was obtained in 20 patients. One-year outcomes were compared based on management. RESULTS: The most common CTA finding was necrosis (94%), followed by exposed artery (73%), viable tumor (67%), pseudoaneurysm (58%), and contrast extravasation (30%). Exposed artery, pseudoaneurysm, and contrast extravasation were the 3 CTA findings related to outcomes. All of the pseudoaneurysm and contrast extravasation cases were associated with an exposed artery. An exposed artery was the most important prognostic predictor and could not be diagnosed on DSA. Patients without the 3 findings on CTA (group 1) had the best survival rate at 1-year follow-up, followed by patients with the 3 findings treated immediately by permanent artery occlusion (group 2). Patients with the 3 findings who had no immediate treatment (group 3) had the worst outcomes (P < .001 in group 1 vs group 3 and group 2 vs group 3; P = .056 group 1 vs group 2). CONCLUSIONS: CTA, with its ability to diagnose an exposed artery compared with DSA, may offer important management and prognostic information in patients with impending carotid blowout.

Impedance monitor to protect the thyratron in metal vapor lasers

It is found that the appearance of high reverse‐voltage spikes on the thyratron anode in the discharge of metal vapor lasers due to high laser impedances can easily be monitored by a dc current meter in series with the bypass inductor of the discharge circuit. Experiments are demonstrated using a copper vapor laser. Results show that the proposed impedance monitor is effective, reliable, and economical. The meter deflection corresponding to acceptable, well‐behaved thyratron operation can be obtained easily by the residual ionization‐control method using a clean laser tube. By keeping the deflection within a specified limit, the lifetime of thyratron can greatly be extended.