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871.
The signal amplification technique of peptide nucleic acid (PNA)-based electrochemical DNA sensor was developed in a label-free and one-step method utilizing enzymatic catalysis. Electrochemical detection of DNA hybridization on a PNA-modified electrode is based on the change of surface charge caused by the hybridization of negatively charged DNA molecules. The negatively charged mediator, ferrocenedicarboxylic acid, cannot diffuse to the DNA hybridized electrode surface due to the charge repulsion with the hybridized DNA molecule while it can easily approach the neutral PNA-modified electrode surface without the hybridization. By employing glucose oxidase catalysis on this PNA-based electrochemical system, the oxidized mediator could be immediately reduced leading to greatly increased electrochemical signals. Using the enzymatic strategy, we successfully demonstrated its clinical utility by detecting one of the mutation sequences of the breast cancer susceptibility gene BRCA1 at a sample concentration lower than 10(-9) M. Furthermore, a single base-mismatched sample could be also discriminated from a perfectly matched sample. 相似文献
872.
Sun Young Kim Yun Seon Yeon Seung Min Park Jeong Hyun Kim Jae Kyu Song 《Chemical physics letters》2008,462(1-3):100-103
Photoluminescence (PL) of zinc oxide (ZnO) nanorods with an average thickness of 5 nm and a length of 30 nm is blue-shifted compared to the bulk due to quantum confinement effects. The exciton states remain relatively stable at a high carrier density due to a smaller exciton size and an enhanced exciton binding energy in the quantum confined nanorods, whereas the electron-hole plasma states are formed in the bulk at the similar carrier density. A linear dependence of the PL intensity on the excitation intensity also corroborates the assumption that the stable exciton states are responsible for the undisturbed emission at a high carrier density. 相似文献
873.
Hak‐Ju Lee Seon‐Mi Seo Oh‐Kyu Lee Hyun‐Jin Jo Ha‐Young Kang Don‐Ha Choi Ki‐Hyon Paik Merajuddin Khan 《Helvetica chimica acta》2008,91(12):2361-2366
The Et2O‐soluble fraction from the bark of Magnolia kobus led to the isolation of two new lignans, (+)‐(7α,7′α,8α,8′α)‐3′,4,4′,5,5′‐pentamethoxy‐7,9′: 7′,9‐diepoxylignan‐3‐ol ( 1 ) and (+)‐(7α,7′α,8α,8′α)‐4,5‐dimethoxy‐3′,4′‐(methylenedioxy)‐7,9′: 7′,9‐diepoxylignan‐3‐ol ( 2 ), along with five known lignans 3 – 7 . Their structures were established on the basis of various spectroscopic analyses including 1D‐ (1H, 13C, and DEPT) and 2D‐NMR (COSY, NOESY, HMQC, and HMBC) and by comparison of their spectral data with those of related compounds. 相似文献
874.
The reaction of (COD)PdCl 2 (COD = 1,5-cyclooctadiene) with bis(3-pyridyl)methylphenylsilane (L) in acetone affords single crystals consisting of cyclodimers, [PdCl 2(L)] 2, whereas the reaction in a mixture of dichloromethane and ethanol yields amorphous spheres consisting of cyclotrimers, [PdCl 2(L)] 3. The interconversion and morphology control between the crystals and the microspheres can be explained by the difference in flexibility between the cyclodimer and cyclotrimer. 相似文献
875.
Indium was substituted at gallium site in chalcopyrite AgGaS(2) structure by using a simple solid solution method. The spectroscopic analysis using extended x-ray absorption fine structure and x-ray photoelectron spectroscopy confirmed the indium substitution in AgGaS(2) lattice. The band gap energy of AgGa(1-x)In(x)S(2) (x=0-1) estimated from the onset of absorption edge was found to be reduced from 2.67 eV (x=0) to 1.9 eV (x=1) by indium substitution. The theoretical and experimental studies showed that the indium s orbitals in AgGa(1-x)In(x)S(2) tailored the band gap energy, thereby modified the photocatalytic activity of the AgGa(1-x)In(x)S(2). 相似文献
876.
Heung‐Seop Yim Mi‐Ra Kim Gi‐Hyeon Sung Hyun‐A Chung Jin‐Kook Lee Sang‐Gyeong Lee Yong‐Jin Yoon 《Journal of heterocyclic chemistry》2008,45(1):215-220
trans‐2‐(2‐Aryl‐ or heteroarylvinyl)‐4,5‐dichloropyridazin‐3(2H)‐ones 3 were synthesized from 4,5‐dichloropyridazin‐3(2H)‐one via 2 step. The photochemical behavior of 3 in THF, methylene chloride, acetonitrile and methanol is dependent on the kind of aryl or heterocyclic ring and the solvent polarity 相似文献
877.
Kim YK Lee HN Singh NJ Choi HJ Xue JY Kim KS Yoon J Hyun MH 《The Journal of organic chemistry》2008,73(1):301-304
Two new anthracene thiourea derivatives, 1 and 2, were investigated as fluorescent chemosensors for the chiral recognition of the two enantiomers of alpha-amino carboxylates. Especially, host 2 displayed K(L)/K(D) values as high as 10.4 with t-Boc alanine. Furthermore, the D/L selectivity of hosts 1 and 2 is opposite, even though both hosts bear the same glucopyranosyl units. These intriguing opposite D/L binding affinities by 1 and 2 were obtained without/with H-pi interaction between anthrancene moiety and the methyl groups, which were explained by extensive high-level theoretical investigations taking into account the dispersion energy as well as the 2D-NMR chemical shifts. 相似文献
878.
Do Nam Lee Shin Han Kim Sook Hyun Yoon Byeong Hyo Kim 《Journal of organometallic chemistry》2008,693(4):655-666
Several dendritic bridging ligands were designed and synthesized to develop more sensitive and efficient electrochemiluminescent (ECL) polynuclear Ru(II) complexes. Various types of novel two-armed, four-armed and six-armed tris(bipyridyl)ruthenium core dendrimers were synthesized by coordinating dendritic polybipyridyl ligands with Ru(II) complexes, and the effect of the ligand and the dendritic network on the ECL characteristics were studied. Their electrochemical redox potentials, UV, photoluminescence (PL), and relative ECL intensities were also investigated in detail. The synthesized metallodendrimers exhibited strong metal-to-ligand charge transfer (MLCT) absorption at 428-451 nm and emission at 591-601 nm. Most of the newly synthesized metallodendrimers showed enhanced ECL intensities compared to the reference complex, [Ru(o-phen)3](PF6)2. In particular, the ECL intensities of the six-armed heptanuclear ruthenium complexes were almost four times greater than that of [Ru(o-phen)3]2+. These metallodendrimers could be utilized as efficient ECL materials and light emitting devices. 相似文献
879.
880.
Hyunchul Jung Chang Hun Lee Sunbin Jeon Dong Hyun Jo June Huh Sung Hyun Kim 《Adsorption》2016,22(8):1137-1146
Amine double-functionalized adsorbents were fabricated using silica gel as supports and their capabilities for CO2 capture were examined. Aminopropyltrimethoxysilane (1N-APS), and N1-(3-trimethoxysilylpropyl)diethylenetriamine (3N-APS) were used as grafted amine compounds, and tetraethylenepentamine and polyethyleneimine were used as impregnated species. The influence of double-functionalization method on the CO2 adsorption performance and textural properties of adsorbents was investigated. The adsorption capacity, the amine efficiency, and the thermal stability of double-functionalized sorbents depend strongly upon molecular variables associated with two different functional states (i.e., chemically grafted and physically impregnated amines). The temperature dependence of adsorption isotherms reveals that the CO2 adsorption behavior in the double-functionalized adsorbents follow the diffusion limitation model proposed by Xu et al. (Energy Fuels 16:1463–1469, 2002) where the CO2 adsorption is helped by the diffusion of impregnated amines. It is also found that the adsorption isotherm in the double-functionalized sorbent system with a proper choice for grafted and impregnated amines is nearly independent of temperature, which may offer a novel means to fabricate practically useful sorbents that can be used in a wide range of temperature without loss of CO2 adsorption capacity. 相似文献