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排序方式: 共有402条查询结果,搜索用时 218 毫秒
311.
Development and certification of the new NIES CRM 28: urban aerosols for the determination of multielements 总被引:1,自引:0,他引:1
Mori I Sun Z Ukachi M Nagano K McLeod CW Cox AG Nishikawa M 《Analytical and bioanalytical chemistry》2008,391(6):1997-2003
A new environmental certified reference material (CRM) for the determination of multielements in aerosol particulate matter
has been developed and certified by the National Institute for Environmental Studies (NIES), Japan, based on analyses by a
network of laboratories using a wide range of methods. The origin of the material was atmospheric particulate matter collected
on filters in a central ventilating system in a building in Beijing city centre. The homogeneity and stability of this material
were sufficient for its use as a reference material. Values for elemental mass fractions in the material were statistically
determined based on the analytical results of the participating laboratories. Eighteen certified values and 14 reference values
were obtained. The diameters, obtained from a micrographic image using image analysis software, of 99% of the particles were
less than 10 μm, demonstrating that almost all the particles in the material could be classified as particles of 10 μm or
less in aerodynamic diameter. The chemical composition and particle size distribution of this material were close to those
of an authentic aerosol collected in Beijing. NIES CRM 28 is appropriate for use in analytical quality control and in the
evaluation of methods used in the analysis of aerosols, particularly those collected in urban environments in northeast Asia
Figure New NIES CRM 28 Urban Aerosols and photo micrograph of the material 相似文献
312.
Treatment of enynes with a catalytic amount of Rh(II) complex results in skeletal reorganization to give cis-configured 1-vinylcycloalkenes, the formation of which occurs via double cleavage of both C-C double and C-C triple bonds. 相似文献
313.
Renard VT Tkachenko OA Tkachenko VA Ota T Kumada N Portal JC Hirayama Y 《Physical review letters》2008,100(18):186801
An unusual increase of the conductance with temperature is observed in clean quantum point contacts for conductances larger than 2(e2/h). At the same time, a positive magnetoresistance arises at high temperatures. A model accounting for electron-electron interactions mediated by boundaries (scattering on Friedel oscillations) qualitatively describes the observation. It is supported by a numerical simulation at zero magnetic field. 相似文献
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The molecular behaviors of proteins under crowding conditions are crucial for understanding the protein actions in intracellular environments. Under a crowded environment, the distance between protein molecules is almost the same size as the molecular level, thus, both the excluded volume effect and short ranged soft chemical interaction on protein surface could induce the complicated influence on the protein behavior cooperatively. Recently, various kinds of analytical approaches from macroscopic to microscopic aspects have been made to evaluate the crowding effect. The method, however, has not been established to evaluate the surface specific interactions on protein surface. In this study, the analytical method to evaluate the crowding effect has been suggested by using a charge-transfer fluorescence probe, ANS. By employing the unique property of ANS attaching to charged residues on the surface of lysozyme, the crowding effect was focused, while the case was compared as a reference, in which ANS is confined in hydrophobic pockets of BSA. Consequently, the surface specific changes of fluorescence spectra were readily observed under the crowded environment, whereas the fluorescence spectra of ANS in protein inside did not change. This result suggests the fluorescence spectra of ANS binding to protein surface have the capability to estimate the crowding effect of proteins. 相似文献
319.
Gislaine Zulli Patrícia Santos Lopes Maria Valéria Robles Velasco Mara Tânia Silva Alcântara Sizue Ota Rogero Ademar Benévolo Lugao Monica Beatriz Mathor 《Radiation Physics and Chemistry》2010,79(3):286-288
Papain is a proteolytic enzyme that has been widely used as debridement agent for scars and wound healing treatment. However, papain presents low stability, which limits its use to extemporaneous or short shelf-life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system that could be used as medical device. Since these systems must be sterile, gamma radiation is an interesting option and presents advantages in relation to conventional agents: no radioactive residues are formed; the product can be sterilized inside the final packaging and has an excellent reliability. The normative reference for the establishment of the sterilizing dose determines 25 kGy as the inactivation dose for viable microorganisms. A silicone dispersion was selected to prepare membranes containing 2% (w/w) papain. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify whether gamma radiation interferes with the drug-releasing profile. Results showed that irradiation does not affect significantly papain release and its activity. Therefore papain shows radioresistance in the irradiation conditions applied. In conclusion, gamma radiation can be easily used as sterilizing agent without affecting the papain release profile and its activity onto the biocompatible device is studied. 相似文献
320.
Ikuko Nishimura Atsushi HiranoTaro Yamashita Takehiro Fukami 《Journal of chromatography. A》2009,1216(15):2984-2988
An improved method for the high-speed assay for log D (HSLogD) employing an injection marker is described. The critical process of HSLogD is automated sampling of the water phase, which prevents contamination from the octanol phase. However, deployment of HSLogD sometimes produces incorrect and inaccurate values compared with data from closely related methods due to low solubility of compounds or instrument problems. Therefore, careful manual inspection of data is needed to confirm the results obtained by this method. To solve this problem, compounds were screened for suitability as injection markers and 2-(4-methoxyphenoxy)-4,8-dimethylquinoline was the most suitable compound examined. Introduction of the injection marker into the process successfully eliminated the need for the tedious and time-consuming manual inspection process. 相似文献