Characterization of cyclic (aryletherketone)s by matrix-assisted laser desorption ionization time of flight mass spectrometry

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to identify cyclic(aryl ether ketone) oligomers, using 2,5-dihydroxybenzoic acid as a matrix, and Na+ and K+ as cationization agents, The existence of different ring-sized cyclic oligomers up to 9 and their distribution were determined and compared with GPC results, The results indicated that MALDI-TOF MS was a powerful and rapid analytical tool for the cyclic oligomers.

Positive- and negative-ion matrix-assisted laser desorption/ionization mass spectrometry of saccharides

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) of oligosaccharides and polysaccharides has been investigated in detail, It is demonstrated that cationized species of oligosaccharides, [M+Na](+) and [M+K](+), are dominant products under the MALDI condition, and negative ions of oligosaccharides are not formed to any significant extent in this process, The molecular masses of polysaccharides are similarly determined by positive- and negative-ion MALDI-MS with the help of column chromatography. The distinction between positive- and negative-ion MALDI mass spectra of oligo-and polysaccharides indicates that the MALDI processes for saccharides vary with molecular mass. The matrix plays a more important role in the ionization process for oligosaccharides, while in the desorption process for polysaccharides. (C) 1998 John Wiley & Sons, Ltd.

Matrix-assisted laser desorption/ionization of ginsenosides

Molecular weight of 8 ginsenosides and the component of total saponions in American ginseng have been determined by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The average error of the molecular weight of each ginsenoside was found less than 0.05%. The results demonstrate that MALDI-MS is a very simple and useful method to measure the molecular weight of some high polar, thermal unstable small molecules with high sensitivity and reproducibility.

Studies on extracting solutions of endohedral rare-earth metallofullerenes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Thirteen extracting solutions of rare-earth metallofullerenes containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb respectively have been investigated by means of matrix-assisted laser desorption/ionization time-of-night, mass spectrometry. The influences of the positive-ion/negative-ion mode, laser intensity, matrix and mass discrimination to the analytical results are studied, based on which the optimal analytical conditions have been determined. The results show that the extracting solutions contain large quantities of rare-earth metallofullerenes brs;des empty fullerenes, On the basis of comparing their relative intensities, the different structure stabilities and solubilities of metallofullerenes with different rare-earth metals encapsulated into the fullerene cages, as well as some possible reasons to those differences, are discussed.

LIGHT-ASSISTED OXIDATIVE DOPING OF POLYANILINES

A novel doping phenomenon of fully reduced polyaniline and poly-o-methyl-aniline, "light-assisted oxidative doping", was found for the first time. The doping reaction was followed by FTIR, UV-VIS, ESR and electrical conductivity measurements. It was shown that the fully reduced polyanilines in the form of HCl-salts undergo a spontaneous transition from an insulator or semiconductor to a conductor when exposed to air and light, and their final molecular chain structures are analogous to those found in HCl-doped common polyanilines.

Heat-shock protein70 gene expression in four hatchery Pacific Abalone Haliotis discus hannai Ino populations using for marker-assisted selection

Heat shock proteins (Hsps) are molecular chaperones that help organisms cope with stressful conditions. Here, we report on the growth rates and Hsp70 expressions in inbred and hybrid populations of abalone Haliotis discus hannai Ino. In abalone, inbred populations expressed more Hsp70 than hybrid populations at all temperatures, except at very high temperatures close to the physiological limit. At benign temperatures, there was a clear trend towards higher Hsp70 expression in inbred than hybrid populations, whereas at higher temperatures, a trend in the opposite direction was observed. The temperature of maximal Hsp70 expression (T-peak) varied with the population type. The T-peak of inbred populations (26 degrees C) was lower than that of the hybrid populations (28 degrees C). The maximal inducible Hsp70 of inbred populations was higher than that of hybrid populations. The results showed a trend towards higher expression in inbred population at a lower temperature. These results provide direct experimental evidence that hybrids can cope with the intrinsic stress even at non-stressful temperatures. The constitutive Hsp70 may therefore be used for marker-assisted selection in a breeding programme.

Salt-assisted acid hydrolysis of chitosan to oligomers under microwave irradiation

The effect of inorganic salts such as sodium chloride on the hydrolysis of chitosan in a microwave field was investigated. While it is known that microwave heating is a convenient way to obtain a wide range of products of different molecular weights only by changing the reaction time and/or the radiation power, the addition of some inorganic salts was shown to effectively accelerate the degradation of chitosan under microwave irradiation. The molecular weight of the degraded chitosan obtained by microwave irradiation was considerably lower than that obtained by traditional heating. Moreover, the molecular weight of degraded chitosan obtained by microwave irradiation assisted under the conditions of added salt was considerably lower than that obtained by microwave irradiation without added salt. Furthermore, the effect of ionic strength of the added salts was not linked with the change of molecular weight. FTIR spectral analyses demonstrated that a significantly shorter time was required to obtain a satisfactory molecular weight by the microwave irradiation-assisted inorganic salt method than by microwave irradiation without inorganic salts and conventional technology. (C) 2005 Elsevier Ltd. All rights reserved.

Use of computer-assisted sperm analysis (CASA) to evaluate the quality of cryopreserved sperm in red seabream (Pagrus major)

In the present study, the quality of post-thaw sperm of red seabream Pagrus major frozen with 6-24% DMSO was investigated. The motility, average path velocity and fertilizing capacity of fresh and their corresponding post-thaw sperm were examined for evaluation of the post-thaw sperm motion characteristics and its association with fertilizing capacity. An analysis of sperm motility before and after cryopreservation has been performed using computer-assisted sperm analysis (CASA). For post-thaw sperm frozen with 12-21% DMSO, the percentages of motile sperm were not significantly (P > 0.05) changed 10 s after activation. Moreover, the main motility pattern and swimming velocity of the motile post-thaw sperm were not significantly (P > 0.05) changed and the progressive linear motion was still the dominant pattern. However, the total motility of post-thaw sperm (72.3 +/- 6.3%) 30 s after activation was (P < 0.05) lower than the corresponding fresh sperm (82.7 +/- 7.2%). Additionally, the fertilizing capacity of post-thaw sperm was investigated with a standardized sperm to egg ratio 500:1. There is a linear regression relationship between the percentage of motile post-thaw sperm and fertilizing capability. These data demonstrate that 12-21% DMSO can provide good protection to the sperm during the freezing-thawing process. (c) 2006 Elsevier B.V. All rights reserved.

Computer-assisted automatic peak recognition and result evaluation for analysis of chlorinated hydrocarbons in environmental samples

A data manipulation method has been developed for automatic peak recognition and result evaluation in the analysis of organic chlorinated hydrocarbons with dual-column gas chromatography. Based on the retention times of two internal standards, pentachlorotoluene and decachlorobiphenyl, the retention times of chlorinated hydrocarbons can be calibrated automatically and accurately. It is very convenient to identify the peaks by comparing the retention times of samples with the calibrated retention times calculated from the relative retention indices of standards. Meanwhile, with a suggested two-step evaluation method the evaluation coefficients and the suitable quantitative results of each component can be automatically achieved for practical samples in an analytical system using two columns with different polarities and two internal standards. (C) 2002 Elsevier Science B.V. All rights reserved.

Salt-assisted acid hydrolysis of starch to D-glucose under microwave irradiation

The effect of inorganic salts on the hydrolysis of starch in a microwave field was investigated and it was found that some inorganic salts can effectively accelerate the acid hydrolysis of starch. The yield of D-glucose reached 111 wt% (equal to the theoretical yield). (C) 2001 Published by Elsevier Science Ltd. All rights reserved.

Lewis acid assisted ring-closing metathesis of chiral diallylamines: An efficient approach to enantiopure pyrrolidine derivatives

Lewis acid assisted ring-closing olefin metathesis (RCM) of chiral diallylamines, using the second generation RCM ruthenium-based catalyst, leads to enantiopure pyrrolidine derivatives in 79-93% yields under very mild conditions. The scope of the olefin metathesis has been expanded.