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61.
Thermally-induced reaction between bicyclo[5.1.0]octa-2,5-diene (I) and sulphur dioxide under dry conditions is toluene-d8 as solvent leads to the unexpected formation of the hitherto unknown diene sulphone 7-thiabicyclo[4.2.1]nona-2,4-diene 7,7-dioxide (II). 相似文献
62.
Ken Ohwada 《Polyhedron》1983,2(5):423-424
It is shown that the Pauling electronegativity scale χ is closely related to the electrostatic potential near the physical meaningful boundary between the core and valence regions in an atom, and is well reproduced by the relationship: where Nν is the valence electron number and the factor f(n) is empirically given by n being the periodic number. 相似文献
63.
A simple and automated methodology for a sensitive electrochemical detection of enzyme immunoassays that employ alkaline phosphatase (AP) as label has been developed. A flow injection system with programmable pump, valve and cell functions, amperometric detection of indigo and screen-printed electrodes (SPEs) are responsible for the advantages of this methodology. Amperometric detection at a low potential of indigo, the product of the enzymatic hydrolysis of the substrate 3-indoxyl phosphate (IP), is combined with a flow injection system. This incorporates in the flow cell a disposable screen-printed board provided with a graphite working electrode. No electrode pretreatment is necessary to obtain reproducible signals. The system was applied to the determination by an enzyme-linked immunosorbent assays (ELISA) of pneumolysin (PLY), a toxin related to respiratory infections. Linear calibration curves for low and high concentration ranges were obtained. These were also performed in a proteic matrix and linearity was also obtained. 相似文献
64.
The assembly strategy to prepare a monolayer of bovine serum albumin on the surface of silica gel supported gold nanoparticles is described. The stereo‐specific recognition ability of this material was evaluated by enantioresolution of Dansyl‐norvaline. For enantiomeric separation, the influences of buffer concentration and the concentration of organic modifier on the separation performance were investigated. A better separation in terms of enantioresolution and peak shape was found with the phosphate concentration at 30 mM. Moreover, the peak shape and resolution can be improved by the addition of methanol solution. Enantioresolution of Dansyl‐norvaline was obtained from this material at optimized conditions. It appears that the immobilization of a monolayer of bovine serum albumin on gold nanoparticles as the chiral selector of Dansyl‐derivative amino acid is promising. 相似文献
65.
The standardization of EDTA solution against metallic copper as primary standard is studied. Six indicators were examined; titration with PAN as indicator at pH 6 is recommended. 相似文献
66.
Turowski M Yamakawa N Meller J Kimata K Ikegami T Hosoya K Tanaka N Thornton ER 《Journal of the American Chemical Society》2003,125(45):13836-13849
Hydrogen/deuterium isotope effects on hydrophobic binding were examined by means of reversed-phase chromatographic separation of protiated and deuterated isotopologue pairs for a set of 10 nonpolar and low-polarity compounds with 10 stationary phases having alkyl and aryl groups bonded to the silica surface. It was found that protiated compounds bind to nonpolar moieties attached to silica more strongly than deuterated ones, demonstrating that the CH/CD bonds of the solutes are weakened or have less restricted motions when bound in the stationary phase compared with the aqueous solvent (mobile phase). The interactions responsible for binding have been further characterized by studies of the effects of changes in mobile phase composition, temperature dependence of binding, and QSRR (quantitative structure-chromatographic retention relationship) analysis, demonstrating the importance of enthalpic effects in binding and differentiation between the isotopologues. To explain our results showing the active role of the hydrophobic (stationary) phase we propose a plausible model that includes specific contributions from aromatic edge-to-face attractive interactions and attractive interactions of aliphatic groups with the pi clouds of aromatic groups present as the solute or in the stationary phase. 相似文献
67.
Motokawa M Kobayashi H Ishizuka N Minakuchi H Nakanishi K Jinnai H Hosoya K Ikegami T Tanaka N 《Journal of chromatography. A》2002,961(1):53-63
Reduction of through-pore size and skeleton size of a monolithic silica column was attempted to provide high separation efficiency in a short time. Monolithic silica columns were prepared to have various sizes of skeletons (approximately 1-2 microm) and through-pores (approximately 2-8 microm) in a fused-silica capillary (50-200 microm I.D.). The columns were evaluated in HPLC after derivatization to C18 phase. It was possible to prepare monolithic silica structures in capillaries of up to 200 microm I.D. from a mixture of tetramethoxysilane and methyltrimethoxysilane. As expected, a monolithic silica column with smaller domain size showed higher column efficiency and higher pressure drop. High external porosity (> 80%) and large through-pores resulted in high permeability (K = 8 x 10(-14) -1.3 x 10(-12) m2) that was 2-30 times higher than that of a column packed with 5-mirom silica particles. The monolithic silica columns prepared in capillaries produced a plate height of about 8-12 microm with an 80% aqueous acetonitrile mobile phase at a linear velocity of 1 mm/s. Separation impedance, E, was found to be as low as 100 under optimum conditions, a value about an order of magnitude lower than reported for conventional columns packed with 5-microm particles. Although a column with smaller domain size generally resulted in higher separation impedance and the lower total performance, the monolithic silica columns showed performance beyond the limit of conventional particle-packed columns under pressure-driven conditions. 相似文献
68.
G. Mairle Liu Ken Pao G. J. Wagner K. T. Knöpfle H. Riedesel 《Zeitschrift für Physik A Hadrons and Nuclei》1981,301(2):157-163
The reactions22Ne(d, t)21Ne and22Ne(d, τ)21F have been investigated in a parallel experiment atE d=52MeV. Energy spectra of tritons andτ particles have been measured up to excitation energies of 18MeV in both21Ne and21F nuclei. Thel values could be determined, and spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. Together with the results from a preceding \({}^{22}Ne(\vec d, \tau ){}^{21}F\) experiment, several spins could be determined in21F. From a comparison of the triton andτ particle spectra,T=3/2 states in21Ne could be identified and on this basis the new information on spins of21F states could be transferred to their analog states in21Ne. The completeT < andT > parts of the (2s, 1d) strengths could be observed. The 1p strength is highly fragmented. Of theT < part only 60% of the 1p1/2 and 40% of the lp3/2 strength could be found, but the totalT > part of the 1p strength could be localized. The spectroscopic results for positive parity states are in qualitatively good agreement with shell model predictions. 相似文献
69.
1-Chlorovinyl p-tolyl sulfoxides were synthesized from several kinds of cyclic ketones and chloromethyl p-tolyl sulfoxide in good yields. Treatment of the 1-chlorovinyl p-tolyl sulfoxides with cyanomethyllithium at −78°C to room temperature gave spirocyclic enaminonitriles in high yields. Acidic treatment of the enaminonitriles afforded spiro[4.n]alkenones in good yields. By using an unsymmetrical cyclic ketone, α-tetralone, and optically active chloromethyl p-tolyl sulfoxide, this procedure afforded enantiomerically pure spiro[4.5]decenone in good yield with excellent asymmetric induction from the sulfoxide chiral center. By using this method a formal total synthesis of a racemic spirocyclic sesquiterpene, acorone, was realized. 相似文献
70.