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161.
K. Y. Lee Y. Y. Yoon S. Y. Cho K. S. Ko Y. Kim 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(2):287-290
Naturally occurring radionuclides (NORN) such as 40K, 226Ra and 232Th from 44 surface sediment samples collected from four desert regions of Chinese were determined to investigate the regional
characteristics of the source areas of Asian dust. The radionuclides for 41 surface sediment samples collected from seven
sites of the Keum River area in Korea were also determined to compare the regional characteristics with the Chinese desert
area. The specific activities (SA) and the specific activity ratios (SAR) of the radionuclides were investigated for distinguishing
the source region of Asian dust. The SA of 226Ra and 232Th as well as the SAR of 226Ra/40K and 232Th/40K were found to be useful to characterize source area and tracing Asian dust. 相似文献
162.
Remote‐Controlled Release of Singlet Oxygen by the Plasmonic Heating of Endoperoxide‐Modified Gold Nanorods: Towards a Paradigm Change in Photodynamic Therapy 下载免费PDF全文
Dr. Safacan Kolemen Dr. Tugba Ozdemir Dayoung Lee Gyoung Mi Kim Tugce Karatas Prof. Juyoung Yoon Prof. Engin U. Akkaya 《Angewandte Chemie (International ed. in English)》2016,55(11):3606-3610
The photodynamic therapy of cancer is contingent upon the sustained generation of singlet oxygen in the tumor region. However, tumors of the most metastatic cancer types develop a region of severe hypoxia, which puts them beyond the reach of most therapeutic protocols. More troublesome, photodynamic action generates acute hypoxia as the process itself diminishes cellular oxygen reserves, which makes it a self‐limiting method. Herein, we describe a new concept that could eventually lead to a change in the 100 year old paradigm of photodynamic therapy and potentially offer solutions to some of the lingering problems. When gold nanorods with tethered endoperoxides are irradiated at 808 nm, the endoperoxides undergo thermal cycloreversion, resulting in the generation of singlet oxygen. We demonstrate that the amount of singlet oxygen produced in this way is sufficient for triggering apoptosis in cell cultures. 相似文献
163.
164.
A straightforward methodology for the synthesis of multifunctionalized dendrimers that is based on an orthogonal functionalization strategy has been developed. Polyamide-based dendrimers that possess both a single aldehyde and a single azide moiety on their periphery have been synthesized by using a convergent synthetic strategy. These dendrimers can be functionalized quantitatively with small organic and biological molecules that contain hydrazide and/or alkyne groups in which each functional moiety is completely specific for its complementary motif. This orthogonal functionalization strategy has the potential to be used to synthesize multifunctional dendrimers for a variety of applications, which range from targeted biological delivery vehicles to optical materials. 相似文献
165.
Jhung SH Yoon JW Lee JS Chang JS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(22):6502-6507
Several zeolites, such as faujasite, mordenite, and ZSM-5, with various aluminum contents have been used to analyze the effect of aluminum or cation concentration (strength of electrostatic field) on hydrogen adsorption at low temperature. Irrespective of the zeolite structure, the adsorption capacity, isosteric heat of adsorption (-DeltaHads), surface coverage, and micropore occupancy increase with increasing aluminum content of a zeolite. Zeolites with a higher amount of aluminum favorably adsorb hydrogen at relatively low pressures. For zeolites with similar aluminum contents, the adsorption capacity, isosteric heat of adsorption, surface coverage, and micropore occupancy are in the order of mordenite>ZSM-5>faujasite, probably due to differing pore sizes and the presence or absence of pore intersections. This work demonstrates that zeolites with strong electrostatic fields and narrow pores without intersections are beneficial for high hydrogen uptake. 相似文献
166.
Yoon HJ Kim YW Lee BK Lee WK Kim Y Ha HJ 《Chemical communications (Cambridge, England)》2007,(1):79-81
An efficient and highly stereoselective synthesis of D-ribo-(2S,3S,4R)-phytosphingosine was accomplished in 62% overall yield starting from commercially available (2S)-hydroxymethylaziridine via osmium-catalyzed asymmetric dihydroxylation as a key step. 相似文献
167.
168.
Xanthine Sensors Based on Anodic and Cathodic Detection of Enzymatically Generated Hydrogen Peroxide
A xanthine biosensor was fabricated by the covalent immobilization of xanthine oxidase (XO) onto a functionalized conducting polymer (Poly‐5, 2′: 5′, 2″‐terthiophine‐3‐carboxylic acid), poly‐TTCA through the formation of amide bond between carboxylic acid groups of poly‐TTCA and amine groups of enzyme. The immobilization of XO onto the conducting polymer (XO/poly‐TTCA) was characterized using cyclic voltammetry, quartz crystal microbalance (QCM), and X‐ray photoelectron spectroscopy (XPS) techniques. The direct electron transfer of the immobilized XO at poly‐TTCA was found to be quasireversible and the electron transfer rate constant was determined to be 0.73 s?1. The biosensor efficiently detected xanthine through oxidation at +0.35 V and reduction at ?0.25 V (versus Ag/AgCl) of enzymatically generated hydrogen peroxide. Various experimental parameters, such as pH, temperature, and applied potential were optimized. The linear dynamic ranges of anodic and cathodic detections of xanthine were between 5.0×10?6?1.0×10?4 M and 5.0×10?7 to 1.0×10?4 M, respectively. The detection limits were determined to be of 1.0×10?6 M and 9.0×10?8 M with anodic and cathodic processes, respectively. The applicability of the biosensor was tested by detecting xanthine in blood serum and urine real samples. 相似文献
169.
Jang‐Hee Yoon G. Muthuraman JeeEun Yang Yoon‐Bo Shim Mi‐Sook Won 《Electroanalysis》2007,19(11):1160-1166
Pt‐nanoparticles were synthesized and introduced into a carbon paste electrode (CPE), and the resulting modified electrode was applied to the anodic stripping voltammetry of copper(II) ions. The synthesized Pt‐nanoparticles were characterized by cyclic voltammetry, scanning electron microscopy and X‐ray photoelectron spectroscopy techniques to confirm the purity and the size of the prepared Pt‐nanoparticles (ca. 20 nm). This incorporated material seems to act as catalysts with preconcentration sites for copper(II) species that enhances the sensitivity of Cu(II) ions to Cu(I) species at a deposition potential of ?0.6 V in an aqueous solution. The experimental conditions, such as, the electrode composition, pH of the solution, pre‐concentration time, were optimized for the determination of Cu(II) ion using as‐prepared electrode. The sensitivity changes on the different binder materials and the presence of surfactants in the test solution. The interference effect of the coexisted metals were also investigated. In the presence of surfactants, especially TritonX‐100, the Cu(II) detection limit was lowered to 3.9×10?9 M. However, the Pt‐nanoparticle modified CPE begins to degrade when the period of deposition exceeds to 10 min. Linear response for copper(II) was found in the concentration range between 3.9×10?8 M and 1.6×10?6 M, with an estimated detection limit of 1.6×10?8 M (1.0 ppb) and relative standard deviation was 4.2% (n=5). 相似文献
170.
Heong‐Seup Yim Ho‐Kyun Kim Jeum‐Jong Kim Deok‐Heon Kweon Yong‐Jin Yoon Sang‐Gyeong Lee Jung‐Ho Kim 《Journal of heterocyclic chemistry》2007,44(4):909-914
1‐Alkyl‐5‐arylalkoxy‐6‐methoxy‐3,4‐dihydroisoquinolines were synthesized by the alkylation of 1‐alkyl‐5‐hydroxy‐6‐methoxy‐3,4‐dihydroisoquinolines with arylalkyl halide in the presence of potassium carbonate. 1‐Alkyl‐5‐hydroxy‐6‐methoxy‐3,4‐dihydroisoquinolines as key precursor prepared from o‐vaniline via 6 steps. 相似文献