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EP Sheretov VS Gurov MV Dubkov OV Korneeva 《Rapid communications in mass spectrometry : RCM》1999,13(16):1699-1702
In this article we compare the classical monopole mass filter of von Zahn and the monopole mass filter with a hyperbolic V-shaped electrode. The experimental results and those of computer simulation for both mass spectrometers are presented. We show that the replacement of a conventional 90 degrees V-shaped electrode by an electrode with a hyperbolic profile substantially improves the peak shape of any given mass, and increases the mass resolution by a factor of 3-4 and the abundance sensitivity by a factor of 100. The potential of high analytical performance combined with electroforming techniques for electrode manufacture indicate future practical uses of such instruments. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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DC magnetization, neutron depolarization and neutron diffraction (with both polarized and unpolarized neutrons) measurements
have been reported for the Co1.1−x
Zn
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Ge0.1Fe1.2O1 spinels with x=0.5, 0.6 and 0.7. Neutron depolarization and neutron diffraction measurements confirm the presence of a long range ferrimagnetic
ordering of the local canted spins in these ferrite samples. The observed features of low field magnetization have been explained
under the framework of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins. An important
role of magnetic anisotropy (due to the presence of Co2+ ions) in establishing the magnetic ordering and domain kinetics in these ferrites has been observed. 相似文献
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MV Muftakhov YV Vasil'ev VA Mazunov 《Rapid communications in mass spectrometry : RCM》1999,13(12):1104-1108
Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Di Venosa G Hermida L Batlle A Fukuda H Defain MV Mamone L Rodriguez L MacRobert A Casas A 《Journal of photochemistry and photobiology. B, Biology》2008,92(1):1-9
Liposomes of different compositions have been designed to improve delivery of aminolevulinic acid (ALA) and its esterified derivatives ALA-Hexyl ester (He-ALA) and ALA-Undecanoyl ester (Und-ALA) for its use in photodynamic therapy (PDT). Egg yolk phosphatidyl choline (PC), phosphatidic acid (PA) and phosphatidyl glycerol (PG) were employed in the preparation of the liposomes. Sonicated vesicles composed of PC, PC-PG (80:20) or PC-PA (80:20) containing ALA or derivatives were obtained and purified by a minicolumn centrifugation method. PC liposomes presented encapsulation percentages around 6% for 2 mM ALA, 13% for 2 mM He-ALA and 51% for 2 mM Und-ALA. The addition of PG or PA to the formulation, resulted in an increased entrapment: 19% for 2 mM ALA, 69% for 2 mM He-ALA and 87% for 2 mM Und-ALA in PC-PG liposomes and 21% for 2 mM ALA, 60% for 2 mM He-ALA and 87% for 2 mM Und-ALA in PC-PA liposomes. Higher concentrations of ALA or derivatives resulted in lower percentages of entrapment. The three formulations containing ALA or derivatives were stable up to 1 week upon storage at 4 degrees C. However, upon dilution with medium, ALA leaked from the liposomes, while on the contrary, He-ALA was highly retained, being therefore a good choice for its use in PDT. The stability of Und-ALA upon dilution could not be tested, but Und-ALA proved to have the highest entrapment efficacy. 相似文献
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