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991.
A sensitive heterogeneous immunoassay for human IgG and anti-human IgG was developed using an enzyme cascade system in limulus amoebocyte as a signal amplification system. Lipopolysaccharide (LPS) was conjugated to human IgG and anti-human IgG was adsorbed on polystyrene beads. The LPS-labelled human IgG mixed with unlabelled human IgG was allowed to react in a competitive manner with the immobilized anti-IgG on the polystyrene bead surface. After B/F separation, the LPS activity in the supernatant (free) and LPS activity on the bead (bound) were measured by using the chromogenic limulus test. IgG could be measured in the range 10?7-10?11 g ml?1. LPS-labelled anti-IgG and IgG absorbed on polystyrene beads were prepared, and LPS-labeled anti-IgG mixed with unlabelled anti-IgG was allowed to react again in a competitive manner with solid-phase IgG. The LPS activity specifically bound to the bead was then measured. Anti-IgG could be measured in the range 10?7-10?11 g ml?1. 相似文献
992.
Infrared and Raman band frequencies, intensities and line shapes are often sensitive to the local molecular environment determined by molecular conformation, surrounding matrix, temperature, pressure, etc. The variety of local environments experienced by a condensed-phase molecule can lead to vibrational spectra with broad bands containing many overlapped spectral features. The spectral resolution of these overlapped features can be enhanced by making perturbations to the sample environment. Examples of perturbations which can be applied to the sample to enhance the information content of infrared spectra are changes in temperature, concentration and mechanical strain. In each instance, the spectra obtained as a function of the perturbation can be cross-correlated to produce a two-dimensional correlation map defined by two independent wavenumber axes. in this representation, infrared bands which respond to the perturbation in a similar or different manner can be clearly identified. This information can be used to help resolve overlapped bands and make unambiguous band assignments. 相似文献
993.
Shen Y Chen E Ye C Zhang H Wu P Noda I Zhou Q 《The journal of physical chemistry. B》2005,109(13):6089-6095
Two-dimensional correlation spectroscopy has been applied to study PMPCS (poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene}), a representative example of mesogen-jacketed liquid crystalline polymers. With the precise analysis of a series of Fourier transform infrared (FTIR) spectra of PMPCS recorded at varied temperatures, a reasonable mechanism of the development of liquid crystalline (LC) phase is proposed. Before the phase transition, the conformational change of individual side chains occurs sooner than that of the backbone due to the larger motional freedom of the side chains. After the phase transition, however, the readjustment of still somewhat mobile backbone occurs before the ordered, rigid, and mutually interacting side chains. That is, phase transition leading to the LC phase formation brings in a new cooperative restriction of motions to the segments. 相似文献
994.
Yoshitsugu Kojima Arimitsu Usuki Masaya Kawasumi Akane Okada Toshio Kurauchi Osami Kamigaito 《Journal of polymer science. Part A, Polymer chemistry》1993,31(7):1755-1758
Nylon 6–clay hybrid is a molecular composite of nylon 6 and uniformly dispersed silicate layers of montmorillonite. One-pot synthesis of the hybrid was carried out by the following procedures. Montmorillonite was dispersed in water, and then ε-caprolactam, acid (phosphoric acid, hydrochloric acid, benzenesulfonic acid, isophthalic acid, trichloroacetic acid, or acetic acid), and 6-aminocaproic acid were added to the dispersion. The mixtures were reacted at 260°C for 6 h, yielding the nylon 6–clay hybrids (1potNCHs). X-ray diffraction revealed that the silicate layers of 1potNCH by phosphoric acid were uniformly dispersed in the nylon 6 matrix. The 1potNCH had excellent mechanical properties. The strength and the modulus of the hybrid increased compared with previously reported nylon 6–clay hybrid (NCH) synthesized by montmorillonite intercalated with 12-aminolauric acid. The heat distortion temperature (HDT) of the 1potNCH was 160°C, which was 8°C higher than that of NCH. In other 1potNCHs, montmorillonite had a smaller effect on the increase of those properties, and interlayer spacing of montmorillonite was observed at ca. 20 Å. © 1993 John Wiley & Sons, Inc. 相似文献
995.
A one-carbon ring enlarged cyclopropanation or vinylation reaction of cyclic keto eaters or sulfones
On treating potassium salts of n-membered cyclic keto esters or sulfones with phenyl 1-propenyl selenone, a one-carbon ring expansion reaction involving cyclopropanation or vinylation takes place to give the corresponding bicyclo[(n - 1).1.0]alkanones or (n + 1)-membered cyclic ketones bearing vinyl group at their 3-position. 相似文献
996.
Masayoshi Watanabe Nobuhiro Toneaki Yoshio Takizawa Isao Shinohara 《Journal of polymer science. Part A, Polymer chemistry》1982,20(9):2669-2680
The elastomeric ionene polymers characterized by the alternating structure of the rigid polycation segments that contained 4,4′-bipyridilium rings and the flexible polypropyleneoxide (PPO) segments were prepared as a function of chain length of the PPO segments. From the measurements of dynamic mechanical properties and x-ray diffraction patterns of these ionenes and their 7,7,8,8-tetracyanoquinodimethane (TCNQ) salts, a microheterogeneous structure of the PPO segments and the polycation-TCNQ salts segments in the TCNQ salts was estimated. On the basis of this microstructure a change in the conductive and dielectric properties with an increase on the weight fraction of the PPO segments the TCNQ salts (Wf) were discussed. For the simple salts the values of resistivity (ρ) and activation energy of conduction (Ea) were increased with the increase in the value of Wf. The values of ρ for the complex salts also increased with the increase in the value of Wf, whereas the values of Ea were nearly constant (ca. 0.07 eV) until the value of Wf reached 0.8. Strong interaction between \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm TCNQ}^{-\atop\cdot}$\end{document} and TCNQ° molecules facilitated the formation of the continuous conduction columns and did not change their structure and properties. Dielectric constant (ε) of the TCNQ salts attained 102?104. The dielectric behavior was consistent with the conductive behavior, and the appearance of the high ε values was caused by polarization of carrier electrons of the TCNQ salts in the conductive paths isolated or interrupted by the PPO segments. As the Wf value increased, the ε values of the TCNQ salts decreased. The decrease in the number of these paths accompanied by the increase in the Wf value led to reduced ε values. 相似文献
997.
A microbial sensor consisting of immobilized Escherichia coli 215 and an oxygen electrode is described for the determination of vitamin B12. When the sample solution is injected into the microbial electrode system, the increased consumption of oxygen by the micro-organisms causes a decrease in the dissolved oxygen around the porous membrane of the oxygen electrode and the current decreases gradually with time until a steady state is reached. The response time for a rate measurement is 2 h. When 0.5 mg of Escherichia coli 215 is immobilized, a linear relationship is obtained between the current decrease and the vitamin B12 concentration between 5 × 10?9 and 25 × 10?9 g ml?1. 相似文献
998.
Two types of hydrophobic gel particles containing dithizone were prepared, either by the swelling of low cross-linkage polystyrene beads with a dithizone solution in chlorobenzene, or by the gelatinization of a dithizone solution with dibenzalsorbitol. The extraction capacity of the gel particles for metal ions such as mercury, cadmium, zinc and lead from dilute aqueous solution, was investigated at various dithizone concentration and pH values. A column packed with such gel particles is found to be useful for the selective preconcentration or the selective trapping of specific metal ions at low concentration levels. 相似文献
999.
The reaction between an α-pyridinium acetamide bearing an 8-phenylmenthyl group as the chiral auxiliary and β-substituted methylidenemalononitriles gave rise to trans-cyclopropanes with diastereomeric ratios of up to 98:2. For most of the reactions, the absolute stereochemistry of the major product was found to be opposite of that of the major products of the reaction of the corresponding ester series, which also utilized the 8-phenylmenthyl group. 相似文献
1000.
Eishun Tsuchida Takamu Yao Kiwamu Kitamura Isao Shinohara 《Journal of polymer science. Part A, Polymer chemistry》1972,10(12):3605-3613
The analysis of the endgroups of the oligomers produced in the styrene (A)–CCl4(S) system (system I), the methyl methacrylate(B)–CCl4 system (system II), and the styrene–methyl methacrylate–CCl4 system (system III) was carried out in order to clarify the mechanism of the initiation, transfer, and termination. In system I, the number of Cl atoms per oligomer molecule NCl increases with the molar ratio of [S]/[A] when the molar ratio of [S]/[A] is below unity and is about four when the molar ratio of [S]/[A] is above unity, and the number of initiator fragments per oligomer molecule NI decreases with the increase in the molar ratio of [S]/[A]. In system II, NCl is about 0.45 over a considerably wide range of the molar ratio of [S]/[B]. In system III, NCl increases and NI decreases with the increase in the molar ratios of [S]/([A] + [B]) and [A]/[B]. From the data of NCl and NI, the fraction ICC14 of the initiation by the tri-chloromethyl radical in the overall initiation reactions and the fraction TCC14 of the chain transfer reaction of the growing radical of styrene in all the reactions which produce the cooligomer in the system III were calculated. ICCl3 and TCC14 both increase with the molar ratios [S]/([A] + [B]) and [A]/[B]. 相似文献