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Y W Yang

Publications and source records attributed to Y W Yang.

At least 19 recordsLinked to original sources
PubMed2006

Extraction of nanosize copper pollutants with an ionic liquid.

Speciation and possible reaction paths of nanosize copper pollutants extracted with a RTIL (room-temperature ionic liquid ([C4mim][PF6], 1-butyl-3-methylimidazolium hexafluorophosphate)) have been studied in the present work. Experimentally, in a very short contact time (2 min), 80-95% of nanosize CuO as well as other forms of copper (such as nanosize Cu, Cu2+, or Cu(II)(ads) (in the channels of MCM-41)) in the samples could be extracted into the RTIL. The main copper species extracted in the RTIL as observed by XANES (X-ray absorption near edge structure) were Cu(II). Existence of Cu-N bondings with coordination numbers (CNs) of 3-4 for copper extracted in the RTIL was found by EXAFS (extended X-ray absorption fine structural) spectroscopy. Interestingly, chelation of Cu(II) with 1-methylimidazole (MIm) in the RTIL during extraction was also observed by 1H NMR (nuclear magnetic resonance). At least two possible reaction paths for the rapid extraction of nanosize copper pollutants with the RTIL might occur: (1) an enhanced dissolution of nanosize CuO (to form Cu2+) and (2) formation of [Cu(MIm)4(H2O)2]2+ that acted as a carrier of copper into the RTIL matrix.

Copper↗
PubMed2004

Two novel mutations of the glycine receptor gene in a Taiwanese hyperekplexia family.

The authors report a Taiwanese family with autosomal recessive hyperekplexia. Two novel mutations, W96C (from the paternal allele) and R344X (from the maternal allele), which are located in exon 4 and exon 7 of the GLRA1 gene, were identified in this family. A series of electrophysiologic investigations were conducted in one of the probands, and the results suggest that the "startle center" is located subcortically.

Acoustic Stimulation↗
PubMed2001

Mineralization of CCl4 with copper oxide.

Experimentally, CCl4 was effectively mineralized by CuO to yield stable inorganic species of CO2 and CuCl2 (CCl4 + 2CuO --> 2CuCl2 + CO2). High CCl4 conversions (63-83%) were found in the mineralization process performed at 513-603 K for 10-30 min. Using X-ray-absorption near edge structure (XANES) and X-ray photoelectron spectroscopies, we found that most CuCl2 was encapsulated in the CCl4-mineralized product solid (mineralization at 513 K for 30 min). At higher mineralization temperatures (563-603 K), CuCl2 was found to be predominant on the surfaces of the mineralization product. Speciation of copper in the mineralization product solid was also studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. Bond distances of Cu-O and Cu-Cl in the CCl4-mineralized product solid were 1.93-1.94 and 2.10-2.12 , respectively, which were greater than those of normal CuO and CuCl2 by 0.03-0.07 A. The increase of the bond distances for Cu-O and Cu-Cl might be due to Cl insertion and concomitant structural perturbation of unreacted CuO in the mineralization process. Forthe second shell around copper atom, bond distances of Cu-(O)-Cu also increased by 0.03-0.05 A, and the coordination numbers of Cu-O and Cu-(O)-Cu decreased, as expected, in the mineralization process. In addition, stoichiometrically excess oxygen atoms were found on the solid surfaces, and they might play an important role in the mineralization of CCl4, leading to the formation of CO2 and Cl. Chloride atoms might be further captured by CuO, yielding CuCl2 in the mineralization process. This work exemplifies the utilization of X-ray spectroscopies (XANES, EXAFS, and XPS) to reveal the speciation and possible reaction pathway in a very complex mineralization process in detail.

Carbon Tetrachloride↗
PubMed2001

NEXAFS study of 1-butanethiol adsorbed on Cu(111) and square root of 7 x square root of 7 R19.1 degrees S/Cu(111).

The adsorption of 1-butanethiol on Cu(111) and square root of 7 x square root of 7 R19.1 degrees S/Cu(111) surfaces has been studied by S K-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy and thermal desorption spectroscopy. Upon adsorption on clean Cu(111) surface at room temperature, butanethiolate as well as atomic sulfur is formed. For the butanethiolate, the S-C bond is found predominately perpendicular to the surface as revealed by polarization analysis. In contrast, on square root of 7 x square root of 7 R19.1 degrees S/Cu(111) surface, the S-H and S-C bonds of the butanethiol stay intact, resulting in a weakly chemisorbed butanethiol.

Adsorption↗
PubMed2001

EXAFS and XANES studies of copper in a solidified fly ash.

Speciation of copper in the fly ash solidification process has been studied by X-ray based spectroscopies inthe present work. Fourier transformed EXAFS (extended X-ray absorption fine structural) spectra of the solidified fly ashes showed that the bond distance of Cu-O (first shell) was 1.96 A with a coordination number (CN) of about 3.0. However, in the second shell of copper atoms, the bond distance of Cu-(O)-Cu was decreased by 0.12-0.22 A during solidification, which might cause the stabilization of the CuO species in the solidified fly ash matrix. By the least-squares fits of the XANES (X-ray absorption near edge structural) spectra, fractions of the main copper species in the solidified fly ashes such as CuCl2 (0.08-0.11), Cu2O (0.07-0.09), Cu(OH)2 (0.31-0.33), and CuO (0.49-0.52) were observed. Combined EXAFS and XANES observations suggested that chemical reactions such as hydroxylation of CuCl2 and oxidation of Cu2O and/or metallic Cu might involve in the solidification process, which also led to a significant reduction of the leachability of copper from the solidified fly ashes.

Air Pollutants↗
PubMed2001

In-situ EXAFS study of copper in the electrokinetic remediation process.

The speciation of copper in the early stage of the electrokinetic remediation (EKR) process has been studied by extended X-ray absorption fine structure (EXAFS) spectroscopy in the present work. By in-situ EXAFS, we found that copper in a contaminated soil possessed a Cu-O bond distance of 1.98 A with a coordination number (CN) of 5.8. In the second shell, the bond distance of Cu-(O)-Cu was 2.87 A with a CN of 6.4. However, possibly due to the fact that incompact copper atoms in the outer shells were distorted by EKR, the Cu-(O)-Cu (2nd shell) bond distance and the CN of copper in the contaminated soil decreased by 0.08 A and 5.4, respectively in the early stage of the EKR process. Interestingly, after prolonging the contact time to about 80 minutes, the 1st-shell copper atoms were also perturbed by EKR. This work is an example of usefulness of the in-situ EXAFS spectroscopy for detailed studies of the speciation of copper in the contaminated soil during EKR process.

Copper↗
PubMed2001

Speciation of As in the blackfoot disease endemic area.

Speciation of arsenic (As) in well water and contaminated soil in the blackfoot disease endemic area has been studied by extended X-ray absorption fine structural (EXAFS) spectroscopy in the present work. Experimentally, we found that arsenic in the well water possessed an As-O bond distance of 1.72 A with a coordination number (CN) of 4.3. In the blackfoot disease area, arsenic with a high oxidation state (As(V)) was also observed in the contaminated soil. In the early stage (after 90 minutes) of the electrokinetic remediation (EKR) of the contaminated soil, the in-situ EXAFS data indicated that the CN of As-O (1st shell) decreased slightly, that may be due to the perturbation of the incompact As atoms in the outer shells by EKR.

Arsenic↗
PubMed2001

Chromium speciation in residues after sequential extraction of a thermally treated sludge analog.

XANES fitting indicates that non-Cr2O3 form of Cr(III), transformed from CrO3 by four-hour heat application at 1100 degrees C, is the key species sorbed onto or lattice-diffused into kaolin matrices that exhibits strong leaching resistance to sequential extraction using various combined solutions including HNO3, H2O2, and HF. The EXAFS spectra are all in agreement with the XANES results. It is suggested that some Cr2O3 might have reacted with kaolin to form new compounds such as Cr2O3 x Al2O3 x 2SiO2 to account for the slight dissimilarity between the EXAFS spectra of samples and that of Cr2O3.

Chromates↗
PubMed2001

EXAFS study of copper in waste incineration fly ashes.

Copper species such as CuCO3, Cu(OH)2, CuS and CuO were found in the bag house and EP (electrostatic precipitator) fly ashes of waste incineration processes by X-ray absorption near edge structural (XANES) spectroscopy. A small amount of Cu(I) and metallic Cu was found in the bag house fly ash. The averaged Cu-O bond distance in the fly ashes determined by EXAFS (extended X-ray absorption fine structural) was 1.96 A with coordination numbers of 2.4-3.9. However, the Cu-(O)-Cu (2nd shell) bond distance of the fly ashes in the incineration process was decreased by 0.19-0.21 A if compared to that of the CuO standard. The coordination numbers of the 2nd shell contribution to the bag house fly ash were not very significant.

Carbon↗
PubMed2001

Study of thermally immobilized Cu in analogue minerals of contaminated soils.

Thermal immobilization of copper contaminants in soil analogue minerals, quartz and kaolin, at low temperatures such as 300 degrees C is studied to corroborate its technical feasibility as a method for soil remediation. We use a synchrotron-based, X-ray absorption spectroscopy (XAS) technique to study the speciation of and the local structure around copper in the soil analogues that are thermally treated at 300-900 degrees C for 1 h. The toxicity characteristic leaching procedure (TCLP) method is employed to investigate the leaching behavior of copper compounds. CuO, being predominately transformed from Cu(OH)2 with a lesser amount from Cu(NO3)2 by 1-h heat application at 300-900 degrees C, is identified by the spectroscopy of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) as the key species that is leaching-resistant due to its low solubility and its chemisorption onto the soil analogue minerals. Fourier transform of EXAFS spectrum of the Cu-doped kaolin heated at 900 degrees C for 1 h indicates that the intensity of Cu-Cu peaks (2.50 and 5.48 A, both without phase shift correction) is either relatively smaller or disappearing as compared with that of kaolin samples heated at 300 and 500 degrees C. The EXAFS analysis suggests that the Cu solid phase in the 900 degrees C kaolin sample is different from the lower temperature samples, the 900 degrees C SiO2 sample, and the Cu standards. The leaching studies also support the formation of a less soluble phase in the 900 degrees C kaolin sample. An increase of heating temperature, in the range of 105-900 degrees C, reduces the Cu leaching percentage; this reduction trend is more marked for Cu-doped kaolin than for Cu-doped SiO2.

Copper↗
PubMed2001

Protamine sulfate enhances the transduction efficiency of recombinant adeno-associated virus-mediated gene delivery.

PURPOSE: The purpose of this study was to evaluate glucose responsiveness in HepG2 human hepatoma cells transduced by a recombinant adeno-associated virus (rAAV) vector containing the insulin gene promoter. and to investigate the effect of protamine sulfate on rAAV-mediated gene delivery. METHODS: Recombinant AAV vector, AAV.Ins.Luc.delta EGFP, was employed to transduce HepG2 hepatoma cells. Virus infection was carried out either in the absence or presence of protamine sulfate, followed by fluorescence microscopic examination, luciferase activity assay, and flow cytometric analysis. Electrokinetic measurements were carried out to determine the effect of protamine sulfate on zeta potential of the cells and the virus. RESULTS: Glucose-responsive luciferase gene expression was obtained in rAAV-transduced HepG2 cells. Addition of 5 microg/ml protamine reversed the zeta potential of the cells and the virus particles, leading to enhanced transgene expression in rAAV-transduced HepG2 cells. Enhancement of protamine sulfate on rAAV-mediated gene transfer was dose-dependent. Addition of more than 5 microg/ml protamine resulted in a reduction of infectability of the virus. CONCLUSIONS: Glucose responsiveness in the millimolar concentration range can be obtained in rAAV-transduced HepG2 cells. Protamine sulfate, up to 5 microg/ml, enhanced the rAAV transduction efficiency in HepG2 cells. The enhancement was correlated with zeta potential of the cells and the virus.

DNA, Recombinant↗
PubMed2001

Regulated secretion of proinsulin/insulin from human hepatoma cells transduced by recombinant adeno-associated virus.

To employ hepatocytes as surrogate beta-cells for gene therapy of diabetes, a regulatory system was devised in this study by placing the human insulin cDNA under the control of the phosphoenolpyruvate carboxykinase (PEPCK) promoter, followed by the cytomegalovirus immediate early promoter-driven enhanced-green-fluorescent-protein open reading frame. The expression cassette was inserted into the adeno-associated virus vector between two inverted terminal repeats, and used to produce recombinant adeno-associated virus (rAAV). HepG2 human hepatoma cells were transduced by rAAV at the desired multiplicity of infection, followed by treatment with various concentrations of retinoic acid, dexamethasone, dibutyryl cAMP (dbcAMP) and 3-isobutyl-1-methylxanthine (IBMX). The cell-culture media were collected at 8, 16 and 24 h later. Proinsulin/insulin levels were determined with human proinsulin/insulin radioimmunoassay kits. Transduction of HepG2 cells by rAAV showed that green fluorescence was produced as early as 12 h after rAAV infection. Flow-cytometrical analysis demonstrated that transduction efficiency increased with the numbers of transducing rAAV particles used. The transduced hepatocytes were shown to secrete immunoreactive proinsulin/insulin, which were stimulated by the concentrations of retinoic acid, dexamethasone and dbcAMP in the culture medium. High conversion from proinsulin into insulin occurred when these cells were treated with dexamethasone and dbcAMP. The presence of IBMX enhanced the secretion of proinsulin/insulin from the dbcAMP-treated cells. We conclude that rAAV is a promising vector for gene therapy of diabetes. Regulated secretion of proinsulin/insulin can be obtained in the rAAV-transduced HepG2 cells conferred with the PEPCK promoter via rAAV-mediated gene transfer.

Blotting, Southern↗
PubMed2001

Reversal of mivacurium chloride: edrophonium of spontaneous recovery in microscopic laryngeal surgery.

BACKGROUND: A double-blind, randomized study was designed to compare the recovery manner of mivacurium infusion with or without edrophonium reversal in microscopic laryngeal surgery. Neuromuscular blockade was quantified using the train-of-four stimuli to the ulnar nerve and quantification of the ratio of the fourth twitch to the first twitch. METHODS: With the approval of the Human Studies Committee of the Taipei Veterans General Hospital and patient informed consent, 40 healthy (ASA I or II) patients with age from 24 to 54 years, undergoing microscopic laryngeal surgery were randomly selected for study. Mivacurium chloride 0.2 mg/kg was given intravenously, and then it was given in continuous infusion to maintain muscle relaxation at 90% twitch block during the procedure. At the end of operation, mivacurium infusion was terminated. In a double-blind manner, group I patients (n = 20) received intravenous edrophonium 1 mg/kg and atropine 0.01 mg/kg for reversal when T1 was at 10% recovery whereas patients in Group II (n = 20) received placebo in the same manner. Mean infusion rate, recovery index (RI50, time from T1 25% to T1 50%; RI75, time from T1 25% to T1 75%), extubation time, and discharge time between groups were compared. Nausea, vomiting, and dysrhythmias were also documented until the patient was discharged from hospital. RESULTS: The demographic data between two groups were similar. The recovery index (RI75) for group I was shorter than that of placebo group (5.3 +/- 2.19 min vs. 7.3 +/- 0.9 min) and the difference was statistically significant (P = 0.017). There were no statistically significant differences in mean infusion rate, incidence of nausea and vomiting, and discharge time from the POR. The incidence of tachycardia or arrhythmia in group I was significantly greater than that in group placebo. CONCLUSIONS: Mivacurium, a short-acting nondepolarizing agent, is a suitable muscle relaxant for patients receiving microscopic laryngeal surgery. Recovery time with the use of edrophonium as reversal agent was shorter than with placebo, but extubation and discharge time did not differ in two groups. The time which could be saved by the use of edrophonium for reversal of mivacurium to hasten the maximal recovery appears to be less than a few minutes. Therefore, clinically, the value of routine use of edrophonium to obtain a faster recovery does not outweigh its demerits of cost and risk and is not worthy of recommendation.

Adult↗
PubMed2000

Fate of bromine in pyrolysis of printed circuit board wastes.

Behavior of Br in pyrolysis of the printed circuit board waste with valuable copper and oil recycling has been studied in the present work. Experimentally, pyrolysis of the printed circuit board waste generated approximately 40.6% of oils, 24.9% of noncondensible gases and 34.5% of solid residues that enriched in copper (90-95%). The cuts of the oils produced from pyrolysis of the printed circuit board waste into weighted boiling fraction were primarily light naphtha and heavy gas oil. Approximately 72.3% of total Br in the printed circuit board waste were found in product gas mainly as HBr and bromobenzene. However, by extended X-ray absorption fine structural (EXAFS) spectroscopy, Cu-O and Cu-(O)-Cu species with bond distance of 1.87 and 2.95 A, respectively, were observed in the solid residues. Essentially, no Cu-Br species was found.

Bromine↗