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排序方式: 共有1063条查询结果,搜索用时 8 毫秒
911.
Young Bok Ryu Man Sig Lee Seong Soo Park Gun-Dae Lee Seong-Soo Hong 《Reaction Kinetics and Catalysis Letters》2005,84(1):101-108
Summary TiO2 nanoparticles were prepared by the hydrolysis of titanium tetraisopropoxide (TTIP) using TMA (tetramethylamine) as a peptizer in the hydrothermal method. The photocatalytic degradation of Orange II has been studied in a batch reactor under UV light. The particle size was similar to that from hydrothermal treatment at 120-170oC, but it increased to 23 nm at 200oC. The titania particles prepared at 170oC and calcined at 600oC showed the highest activity in the photocatalytic decomposition ofOrange II. 相似文献
912.
Capillary electrophoresis of high-molecular chitosan: the natural carbohydrate biopolymer 总被引:1,自引:0,他引:1
Due to its high resolving power and diverse application range, capillary electrophoresis (CE) has been successfully applied to the analysis of carbohydrates. In this paper, a method for the determination of high-molecular chitosan (Mr 200,000) using CE is presented. We studied the optimal condition of buffer pH and type, and column type for determination of chitosan. Optimal CE performance was found when employing 100 mM triethylamine (TEA)-phosphate buffer, pH 2.0 and untreated fused-silica capillary (50 microm x 27 cm) for the chitosan analysis. Under optimum conditions, excellent linear responses were obtained in the concentration range of 1.25-20 microM, with a linear correlation coefficient of 0.9983. The standard deviations of the migration time and peak area were found to be 2.5 and 6.4%, respectively. This method could be readily applied to chitosan determination in real biological samples and commercial products. 相似文献
913.
Azumaya I Kato T Okamoto I Yamasaki R Tanatani A Yamaguchi K Kagechika H Takayanagi H 《Organic letters》2003,5(21):3939-3942
[reaction: see text] 1,2-Bis(N-benzenesulfonyl-N-methylamino)benzene (2), which has no fixed asymmetric element, was crystallized from ethyl acetate as chiral crystals belonging to space group P4(1)2(1)2 (No. 92) or P4(3)2(1)2 (No. 96). The array of molecules built by the CH-pi interaction along the c-axis forms an enantiomeric helical superstructure in each individual crystal. The absolute configurations of the chiral crystals of 2 were determined by X-ray crystal structure analysis using the Flack parameter method. The solid-state CD spectra of the chiral crystals in KBr were mirror images. The equilibrium between the two enantiomers in solution is fast during crystallization at ambient temperature, and the energy barrier (DeltaG()) is estimated to be 11.7 +/- 0.3 kcal/mol (233 K). 相似文献
914.
Hui Bin Jeon Sehoon Park Kyeong Rim Ryu Suman Kr Ghosh Jaehoon Jung Kyeng Min Park Ji Won Ha 《Chemical science》2021,12(20):7115
Recently, chemical interface damping (CID) has been proposed as a new plasmon damping pathway based on interfacial hot-electron transfer from metal to adsorbate molecules. It has been considered essential, owing to its potential implications in efficient photochemical processes and sensing experiments. However, thus far, studies focusing on controlling CID in single gold nanoparticles have been very limited, and in situ reversible tuning has remained a considerable challenge. In these scanning electron microscopy-correlated dark-field spectroscopic measurements and density functional theory calculations, cucurbit[7]uril (CB[7])-based host–guest supramolecular interactions were employed to examine and control the CID process using monoamine-functionalized CB[7] (CB[7]-NH2) attached to single gold nanorods (AuNRs). In situ tuning of CID through the CB[7]–oxaliplatin complexation, which can result in the variation of the chemical nature and electronic properties of adsorbates, was presented. In addition, in situ tuning of CID was demonstrated through the competitive release of the oxaliplatin guest from the oxaliplatin@CB[7] complex, which was then replaced by a competitor guest of spermine in sufficient amounts. Furthermore, nuclear magnetic resonance experiments confirmed that the release of the guest is the consequence of adding salt (NaCl). Thus, in situ reversible tuning of CID in single AuNRs was achieved through successive steps of encapsulation and release of the guest on the same AuNR in a flow cell. Finally, single CB[7]-NH2@AuNRs were presented as a recyclable platform for CID investigations after the complete release of guest molecules from their host–guest inclusion complexes. Therefore, this study has paved a new route to achieve in situ reversible tuning of CID in the same AuNR and to investigate the CID process using CB-based host–guest chemistry with various guest molecules in single AuNRs for efficient hot-electron photochemistry and biosensing applications.This study has paved a new route to achieve in situ reversible tuning of chemical interface damping (CID) in the same gold nanorod (AuNR) and to investigate the CID process using cucurbituril (CB)-based host–guest chemistry with various guest molecules in single AuNRs. 相似文献
915.
The β-(trifluoromethyl)vinylsulfides on treatment with n-BuLi/TMEDA were readily lithiated at α-position of the sulfanyl group, and the generated α-lithiovinylsulfides were trapped with a variety of electrophiles to give the corresponding β-trifluoromethyl-α-functionalized vinylsulfides in good to high yields. 相似文献
916.
Ogawa S Yoshimura S Nagahora N Kawai Y Mikata Y Sato R 《Chemical communications (Cambridge, England)》2002,(17):1918-1919
The molecular structure of novel five-membered trichalcogenaheterocycles with three different chalcogen atoms, sulfur, selenium and tellurium, has been determined by crystallographic studies. 相似文献
917.
Masayoshi?OkuboEmail author Ryu?Takekoh Naohiko?Saito 《Colloid and polymer science》2004,282(11):1192-1197
The formation mechanism of the onionlike multilayered morphology of micron-sized, monodisperse poly(methyl methacrylate) (PMMA)/polystyrene (PS) (1/1 w/w) composite particles by the solvent-absorbing/solvent-releasing method was discussed. It was concluded that the orientation of PMMA components at the outer interface of toluene-swollen particles with water is the trigger and that PMMA-g-PS operates to stabilize inner multilayer interfaces for the formation of the onionlike multilayered morphology.Part CCLV of the series Studies on suspension and emulsion 相似文献
918.
Ryu I Matsubara H Yasuda S Nakamura H Curran DP 《Journal of the American Chemical Society》2002,124(44):12946-12947
In fluorous triphasic reactions, such as bromination of alkenes by dibromine and dealkylation of aromatic ethers by boron tribromide, the middle fluorous phase acts as a liquid membrane permitting passive transport of the reagents at the bottom to the top layer involving the substrates, thereby regulating the reactions. 相似文献
919.
Molecular orbital calculations predict that the 5-azahexenoyl radical ring closes via nucleophilic addition to the acyl carbon to afford the 5-exo product; CCSD(T)/cc-pVDZ/ /BHLYP/cc-pVDZ calculations predict energy barriers of 36.1 and 46.9 kJ mol-1 for the exo and endo cyclization modes of the 5-azahexenoyl radical, respectively. 相似文献
920.