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111.
Wei-Jing Gao Chiu Marco Lam Bao-Guo Sun R. Daniel Little Cheng-Chu Zeng 《Tetrahedron》2017,73(17):2447-2454
The electrochemically oxidative cleavage of lignin β-O-4 model compounds mediated by iodide ion has been studied. The results indicate that electrolytic conditions play a predominant role in determining the distribution of cleavage products. The preparative-scale electrolysis proceeds in a simple undivided cell, employing a catalytic amount of NaI as the redox mediator and supporting electrolyte in methanol. Under these conditions, the CβO bond is selectively cleaved with 2,2-dimethoxy-2-arylacetaldehyde being the main product. In some cases, the reaction gives a good yield of cleavaged products. The results further demonstrate that the indirect electrolysis mediated by halide is a versatile approach for chemical transformation. 相似文献
112.
Wu C Schneider T Zeigler M Yu J Schiro PG Burnham DR McNeill JD Chiu DT 《Journal of the American Chemical Society》2010,132(43):15410-15417
Semiconducting polymer dots (Pdots) represent a new class of ultrabright fluorescent probes for biological imaging. They exhibit several important characteristics for experimentally demanding in vitro and in vivo fluorescence studies, such as their high brightness, fast emission rate, excellent photostability, nonblinking, and nontoxic feature. However, controlling the surface chemistry and bioconjugation of Pdots has been a challenging problem that prevented their widespread applications in biological studies. Here, we report a facile yet powerful conjugation method that overcomes this challenge. Our strategy for Pdot functionalization is based on entrapping heterogeneous polymer chains into a single dot, driven by hydrophobic interactions during nanoparticle formation. A small amount of amphiphilic polymer bearing functional groups is co-condensed with the majority of semiconducting polymers to modify and functionalize the nanoparticle surface for subsequent covalent conjugation to biomolecules, such as streptavidin and immunoglobulin G (IgG). The Pdot bioconjugates can effectively and specifically label cellular targets, such as cell surface marker in human breast cancer cells, without any detectable nonspecific binding. Single-particle imaging, cellular imaging, and flow cytometry experiments indicate a much higher fluorescence brightness of Pdots compared to those of Alexa dye and quantum dot probes. The successful bioconjugation of these ultrabright nanoparticles presents a novel opportunity to apply versatile semiconducting polymers to various fluorescence measurements in modern biology and biomedicine. 相似文献
113.
Mei‐Hsin Chiu Annamalai Senthil Kumar Sundaram Sornambikai Jyh‐Myng Zen Ying Shih 《Electroanalysis》2010,22(20):2421-2427
A screen‐printed silver strip with a built‐in three‐in‐one electrode (SPAgE) configuration of Ag‐working, Ag‐counter and Ag/AgxO (silver oxides) pseudoreference electrodes has been developed for sensitive and selective electrochemical flow injection analysis (FIA) of aluminum chlorohydrate (ACH) present in antiperspirants, through the free Cl? ion liberated from ACH in aqueous medium, as a redox signal at Ag‐working electrode in pH 6 phosphate buffer solution (PBS). The solution phase and instrumental parameters were systematically optimized. The calibration graph was linear in the window 1–200 ppm concentration of ACH and the lowest detection limit (S/N=3) was 295 ppb with a slope of 0.0989 μA/ppm and regression coefficient of 0.998. Calculated relative standard deviation (RSD) values for the detection of 5 and 50 ppm ACH by this method are 2.21 % and 2.16 %, respectively. Four different antiperspirant deodorants real samples with and without ACH content were successfully analyzed and the detected values obtained were found to be in good agreement with the product labeled values. 相似文献
114.
Kuo-Hsun Chiu Chih-Ching Chang Yu-Chen Chang Jing-Fang Hsu 《Analytica chimica acta》2010,673(2):160-166
Ultrafine carbon black (ufCB) is a potential hazard to the lung. It causes changes in protein expression and it increases alveolar-capillary permeability in the lung. Label-free quantitative proteomic methods allow a sensitive and accurate analytical method for identifying and quantifying proteins in a protein mixture without chemically modifying the proteins. We used a label-free quantitative proteomic approach that combined and aligned LC-MS and LC-MS/MS spectra to analyze mouse bronchoalveolar lavage fluid (BALF) protein changes associated with exposure to ufCB. We developed a simple normalization method for quantification without spiking the internal standard. The intensities of unchanged peptides were used as normalization factors based on a statistical method to avoid the influence of peptides changed because of ufCB. LC-MS/MS spectra and then database searching were used to identify proteins. The relative abundances of the aligned peptides of identified proteins were determined using LC-MS spectra. We identified 132 proteins, of which 77 are reported for the first time. In addition, the expression of 15 inflammatory proteins and surfactant-associated proteins was regulated (i.e., 7 upregulated and 8 downregulated) compared with the controls. Several proteins not previously reported provide complementary information on the proteins present in mouse BALF, and they are potential biomarkers for the understanding of mechanisms involved in ufCB-induced lung disorders hypothesize that using the label-free quantitative proteomic approach introduced here is well suited for more rigorous, large-scale quantitative analysis of biological samples. We hypothesize that this label-free quantitative proteomic approach will be suited for a large-scale quantitative analysis of biological samples. 相似文献
115.
S.-Y. Jou C.-T. Hung Y.-M. Chiu J.-S. Wu B.-Y. Wei 《Plasma Chemistry and Plasma Processing》2010,30(6):907-931
Simulation of excimer ultraviolet (EUV) emission from a coaxial xenon excimer ultraviolet lamp driven by distorted bipolar
square voltages is presented in this study. A self-consistent radial one-dimensional fluid model, considering local mean energy
approximation (LMEA), along with a set of simplified xenon plasma chemistry was employed to simulate the discharge physics
and chemistry. Emitted powers of EUV light and deposited powers to the charged species were simulated by varying the values
of four key parameters, which include the driving frequency, gas pressure, gap distance and number of dielectric layers. Results
show that there are three distinct periods that include pre-discharge, discharge and post-discharge ones. It is found that
intensive EUV (172 nm) emission occurs during the early part of the discharge period, which correlates very well in time with
the power deposition through electrons. In addition, power deposition through
\textXe + {\text{Xe}}^{ + } and
\textXe2 + {\text{Xe}}_{2}^{ + } occurs mainly in the discharge period and later part of discharge period, respectively. Surprisingly, the emission efficiency
of 172 nm increases slightly with increasing driving frequency of power source, while it increases dramatically with increasing
gap distance. In addition, the maximal emission efficiency is found to take place at gas pressure of 600 torr. The emission
efficiency of one-dielectric case is found to be better than that of two-dielectric one. The underlying mechanisms in the
above observations are discussed in detail in the paper. 相似文献
116.
Yu-Yen Kao Kung-Tien Liu Ming-Feng Huang Tai-Chia Chiu Huan-Tsung Chang 《Journal of chromatography. A》2010,1217(4):582-587
We describe simultaneous analysis of naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and NDA-biogenic amine derivatives by CE in conjunction with light-emitting diode-induced fluorescence detection using poly(ethylene oxide) (PEO) solutions containing sodium dodecyl sulfate (SDS). After sample injection, via EOF 0.1% PEO prepared in 100 mM TB solution (pH 9.0) containing 30 mM SDS entered a capillary filled with 0.5 M TB solution (pH 10.2) containing 40 mM SDS. Under this condition, 14 NDA-amino acid and NDA-amine derivatives were separated within 16 min, with high efficiency ((1.0–3.2) × 105 theoretical plates) and sensitivity (LODs at S/N = 3 ranging from 2.06 to 19.17 nM). In the presence of SDS and PEO, analytes adsorption on the capillary wall was suppressed, leading to high efficiency and reproducibility. The intraday analysis RSD values (n = 3) of the mobilities for the analytes are less than 0.52%. We have validated the practicality of this approach by quantitative determination of 9 amino acids in breast cancer cells (MCF-7) and 10 amino acids in normal epithelial cells (H184B5F5/M10). The concentrations of Tau and Gln in the MCF-7 cells were different than those in the H184B5F5/M10 cells, respectively. Our results show the potential of this approach for cancer study. 相似文献
117.
A high contrast and capacity efficient visual cryptography scheme for the encryption of multiple secret images 总被引:1,自引:0,他引:1
The visual secret sharing for multiple secrets (VSSM) allows for the encryption of a greater number of secret images into a given image area. Previous researches on VSSM schemes incur a very serious pixel expansion that will damage capable of increasing the capacity of secret image encryption. Moreover, the most of VSSM schemes will decrease the contrast of recover images while the amount of secret image encryption increases. These drawbacks limit applicability of the existing VSSM schemes. In this paper, we propose a highly efficient encryption algorithm to cope with this problem. The proposed algorithm adopts a novel hybrid encryption approach that includes a VC-based encryption and a camouflaging process. The experimental results demonstrate that the proposed approach not only can increase the capacity efficient for VSSM schemes, but also maintains an excellent level of contrast in the recovered secret images. 相似文献
118.
In this paper, we demonstrate the monolithic integration of a conventional waveguide, a photonic crystal demultiplexer, a photonic crystal taper coupler, photonic crystal waveguides, and photodiodes in InGaAsP-based material to form a planar nano-optics system. Photonic crystal demultiplexers consist of hexagonally arranged air holes. Finite-difference time-domain method is implemented to investigate the performance of the demultiplexer. The system is fabricated using e-beam lithography and conventional photolithography. The input light at wavelengths of 1530 and 1550 nm can be separated using the demultiplexing system. These can then be detected by photodiodes that exhibit a wide-bandwidth performance of 22 GHz. 相似文献
119.
Biological specimens have to be prepared for imaging in the electron microscope in a way that preserves their native structure. Two-dimensional (2D) protein crystals to be analyzed by electron crystallography are best preserved by sugar embedding. One of the sugars often used to embed 2D crystals is trehalose, a disaccharide used by many organisms for protection against stress conditions. Sugars such as trehalose can also be added to negative staining solutions used to prepare proteins and macromolecular complexes for structural studies by single-particle electron microscopy (EM). In this review, we describe trehalose and its characteristics that make it so well suited for preparation of EM specimens and we review specimen preparation methods with a focus on the use of trehalose. 相似文献
120.
A highly sensitive miniature photonic crystal fiber refractive index sensor based on field mode excitation is presented. The sensor is fabricated by melting one end of a photonic crystal fiber into a rounded tip and splicing and collapsing the other end with a single-mode fiber. The rounded tip is able to induce cladding mode excitation, which resulted in an additional phase delay. Linear response of 262.28 nm/refractive index unit in the refractive index range of 1.337 to 1.395 is obtained for the physical length of a 953 μm sensor. The sensor is also shown to be insensitive to environmental temperature. 相似文献