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991.
This review highlights recent developments and applications of on-line sample preconcentration techniques to enhance the detection sensitivity in microchip electrophoresis (MCE); references are mainly from 2008 and later. Among various developed techniques, we focus on the sample preconcentration based on the changes in the migration velocity of analytes in two or three discontinuous solutions system, since they can provide the sensitivity enhancement with relatively easy experimental procedures and short analysis times. The characteristic features of the on-line sample preconcentration applied to microchip electrophoresis (MCE) are presented, categorized on the basis of "field strength-" or "chemically" induced changes in the migration velocity. The preconcentration techniques utilizing field strength-induced changes in the velocity include field-amplified sample stacking, isotachophoresis and transient-isotachophoresis, whereas those based on chemically induced changes in the velocity are sweeping, transient-trapping and dynamic pH junction. 相似文献
992.
Nagaoka T Tokonami S Shiigi H Matsumoto H Takagi Y Takahashi Y 《Analytical sciences》2012,28(2):187-191
In this article, we report on a food-cholesterol monitoring sensor based on a non-enzymatic approach. Amorphous and single-crystal gold electrodes were modified with an alkanethiol self-assembled monolayer to quantify it by voltammetry. We first discuss the basic characteristics of these sensors and provide more information about the instrument developed by JSK Co. This instrument is a battery-operated handheld voltammetric analyzer, which mounts a sensor chip to monitor cholesterol contents in food samples. The sensor showed excellent linearity with the cholesterol concentration; egg-yolk samples were analyzed to give an excellent agreement between the values obtained by the sensor (1.4 mM) and chromatography (1.1 mM). 相似文献
993.
Ken Yoshimura Kei Matsumoto Yasunori Uetani Shigeki Sakumichi Shuichi Hayase Motoi Kawatsura Toshiyuki Itoh 《Tetrahedron》2012,68(18):3605-3610
A study of the design of thiophene-substituted fulleropyrrolidine derivatives as the acceptor in photovoltaic cells has been carried out using poly(3-hexylthiophene) (P3HT) as the model donor polymer. It was found that five types of thiophene-substituted fulleropyrrolidine worked as a good acceptor partner with P3HT, and the highest power conversion efficiency (PCE) was obtained for 1-(2-(2-methoxyethoxy)ethyl)-2-(2-thiophen-2-yl)fulleropyrrolidine (2.99%); this is superior to that of the P3HT polymer including methyl [C60]-PCBM under the same experimental conditions. 相似文献
994.
N-Acylhomoserine lactones (AHLs) are the conserved quorum-sensing signal molecules in Gram-negative bacteria. (Z)-N-(4-Decenoyl)homoserine lactone (1), a new AHL, was isolated from the culture broth of the fungus Mortierella alpina A-178 harboring bacterial endosymbionts, called endobacteria. The structure and absolute configuration of 1 were elucidated by EI-MS, chemical synthesis, and chiral GC analysis. The compound induced the expression of a QS-regulated reporter gene in Agrobacterium tumefaciens NTL4, although its activity was lower than that of N-decanoylhomoserine lactone (6). 相似文献
995.
A tetra-n-butylammonium (TBA) salt of [H(4.5)(Ta(6)O(19))](3.5-) was synthesized by reacting hydrous tantalum oxide with TBAOH. X-ray structural analysis of TBA(3.5)[H(4.5)(Ta(6)O(19))]·2THF·5.5H(2)O (THF = tetrahydrofuran) revealed that this compound consists of a hydrogen-bonded, rod-shaped tetramer of hexatantalate that is almost 30 ? long together with TBA cations and solvent molecules of crystallization [a = 20.6354(5) ?, b = 25.5951(7) ?, c = 37.2058(8) ?, α = 77.092(1)°, β = 86.177(1)°, γ = 88.683(1)°, V = 19110.9(8) ?(3), Z = 8, and space group P ?1]. (1)H NMR spectra showed that this tetrameric structure is maintained in solution. 相似文献
996.
Divalent and trivalent nickel complexes of 1,4,8,11-tetraazacyclotetradecane, denoted as cyclam hereafter, coordinated by methyl coenzyme M (MeSCoM(-)) and coenzyme M (HSCoM(-)) have been synthesized in the course our model studies of methyl coenzyme M reductase (MCR). The divalent nickel complexes Ni(cyclam)(RSCoM)(2) (R = Me, H) have two trans-disposed RSCoM(-) ligands at the nickel(II) center as sulfonates, and thus, the nickels have an octahedral coordination. The SCoM(2-) adduct Ni(cyclam)(SCoM) was also synthesized, in which the SCoM(2-) ligand chelates the nickel via the thiolate sulfur and a sulfonate oxygen. The trivalent MeSCoM adduct [Ni(cyclam)(MeSCoM)(2)](OTf) was synthesized by treatment of [Ni(cyclam)(NCCH(3))(2)](OTf)(3) with ((n)Bu(4)N)[MeSCoM]. A similar reaction with ((n)Bu(4)N)[HSCoM] did not afford the corresponding trivalent HSCoM(-) adduct, but rather the divalent nickel complex polymer [-Ni(II)(cyclam)(CoMSSCoM)-](n) was obtained, in which the terminal thiol of HSCoM(-) was oxidized to the disulfide (CoMSSCoM)(2-) by the Ni(III) center. 相似文献
997.
A copper-catalyzed annulative amination approach to 3-aminobenzofurans and -indoles from o-alkynylphenols and -anilines has been developed. The Cu-based catalysis is based on an umpolung, electrophilic amination with O-benzoyl hydroxylamines and enables the mild and convergent synthesis of various 3-aminobenzoheteroles of biological and pharmaceutical interest. Some mechanistic investigations and an application of this protocol to construction of more complex tricyclic framework are also described. 相似文献
998.
Jovana Francuz Bojana Srećo Mirjana Popsavin Goran Benedeković Vladimir Divjaković Vesna Kojić Gordana Bogdanović Agneš Kapor Velimir Popsavin 《Tetrahedron letters》2012,53(14):1819-1822
Treatment of 7-O-benzoyl-5-O-benzyl derivatives of (+)-goniofufurone or 7-epi-(+)-goniofufurone with titanium(IV) chloride or titanium(IV) bromide gave 7-chloro and 7-bromo-7-deoxy-goniofufurone mimics as the main reaction products along with minor amounts of the corresponding C-7 epimers. An unexpected cyclized product, benzoxepane 8 was isolated in some cases. 相似文献
999.
The first μ-η(2):η(2)-diselenidodicopper(II) complex has been obtained in the reaction of a copper(I) complex with N,N',N″-tribenzyl-cis,cis-1,3,5-triaminocyclohexane and elemental selenium. The structure and reactivity of the complex is described. 相似文献
1000.
On the pressure of cavitation bubbles 总被引:1,自引:0,他引:1
Shock wave emission upon the collapse of a cavitation bubble attached to a rigid wall is investigated using high-speed photography with 200 million frames/s and 5 ns exposure time. At a distance of 68 μm from the bubble wall, the shock pressure is 1.3 ± 0.3 GPa. The shock pressure decays proportionally to r−1.5 with increasing distance from the bubble. An estimation of the peak pressure at the bubble wall reveals a pressure of about 8 GPa. A major part of the shock wave energy is dissipated within the first 100 μm from the bubble wall. 相似文献