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171.
Pulkkinen M Palmgrén JJ Auriola S Malin M Seppälä J Järvinen K 《Rapid communications in mass spectrometry : RCM》2008,22(2):121-129
This paper describes a straightforward and rapid on-line characterization using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS(n)) of the enzymatic degradation products of 2,2'-bis(2-oxazoline)-linked poly-epsilon-caprolactone (PCL-O). These new PCL-O polymers are expected to be used in a variety of pharmaceutical and biomedical applications since they are degraded enzymatically by surface erosion. PCL-O was polymerized in a three-step reaction and characterized by (1)H-NMR and size-exclusion chromatography (SEC). Solvent cast polymer films were exposed to enzymatic degradation in phosphate buffer (pH 7.5, 1% pancreatin). The enzymatic degradation of the polymer produced a wide variety of water-soluble oligomers which were separated and identified by HPLC/ESI-MS(n). Optimization of the gradient HPLC method resulted in effective separation of the oligomers. Furthermore, specific structures of the oligomers were clearly identified by tandem mass spectrometry. According to these results, ester bonds seem to be most sensitive to enzymatic degradation and, correspondingly, pancreatic lipase seems to be mainly responsible for the enzymatic erosion of the PCL-O films. This novel mass spectrometric method provides important knowledge about the enzymatic degradation process and structure of the polymer which is difficult to ascertain by other conventional methods. 相似文献
172.
Ultrasound assisted method to increase soluble chemical oxygen demand (SCOD) of sewage sludge for digestion 总被引:3,自引:0,他引:3
Grönroos A Kyllönen H Korpijärvi K Pirkonen P Paavola T Jokela J Rintala J 《Ultrasonics sonochemistry》2005,12(1-2):115-120
The aim of this study was to clarify the possibilities to increase the amount of soluble chemical oxygen demand (SCOD) and methane production of sludge using ultrasound technologies with and without oxidising agents. The study was done using multivariate data analyses. The most important factors affected were discovered. Ultrasonically assisted disintegration increased clearly the amount of SCOD of sludge. Also more methane was produced from treated sludge in anaerobic batch assays compared to the sludge with no ultrasonic treatment. Multivariate data analysis showed that ultrasonic power, dry solid content of sludge (DS), sludge temperature and ultrasonic treatment time have the most significant effect on the disintegration. It was also observed that in the reactor studied energy efficiency with high ultrasound power together with short treatment time was higher than with low ultrasound power with long treatment time. When oxidising agents were used together with ultrasound no increase in SCOD was achieved compared the ultrasonic treatment alone and only a slight increase in total organic carbon of sludge was observed. However, no enhancement in methane production was observed when using oxidising agents together with ultrasound compared the ultrasonic treatment alone. Ultrasound propagation is an important factor in ultrasonic reactor scale up. Ultrasound efficiency rose linearly with input power in sludge at small distances from the transducer. Instead, ultrasound efficiency started even to decrease with input power at long distances from the transducer. 相似文献
173.
Firas?Rassoul-AghaEmail author Timo?Sepp?l?inen 《Probability Theory and Related Fields》2005,133(3):299-314
We consider a discrete time random walk in a space-time i.i.d. random environment. We use a martingale approach to show that
the walk is diffusive in almost every fixed environment. We improve on existing results by proving an invariance principle
and considering environments with an L2 averaged drift. We also state an a.s. invariance principle for random walks in general random environments whose hypothesis
requires a subdiffusive bound on the variance of the quenched mean, under an ergodic invariant measure for the environment
chain.
T. Sepp?l?inen was partially supported by National Science Foundation grant DMS-0402231. 相似文献
174.
Using a relativistic molecular DFS code we have calculated a self-consistent many electron relativistic correlation diagram of the system Cl-Ar. The resulting energy for the 2pπ-1sσ transition is in complete agreement with the experimental results of Schuch et al./1/. This definitely confirms their claim that they are able to measure this quantity from interference structures observed in quasi-molecular K-X-ray spectra. 相似文献
175.
Johanna Sepp 《Fresenius' Journal of Analytical Chemistry》1960,174(2):159
Ohne Zusammenfassung 相似文献
176.
At the beginning of 1975 the Federation of the Finnish Chemical Industry and the University of Helsinki, Department of Computer Science, set up a project to develop a mathematical model to be used as a planning tool during accidental raw material shortages in the Finnish chemical industry. The model has been designed, programmed, and tested. The main part of the system consists of a linear programming model, which is used to answer “what-if” questions.This paper describes the model, the programs and the main problems encountered in the design process. The present version of the system can solve problems involving at most 100 firms, 400 products, 400 types of raw materials and 200 technical or policy constraints. 相似文献
177.
178.
E. Müller K. Söllner M. Hivná Z. Stejskal Johanna Sepp H. Garschagen Margot Zimmermann B. Rossmann und H. Wunderlich 《Fresenius' Journal of Analytical Chemistry》1961,179(6):459-462
Ohne Zusammenfassung 相似文献
179.
Johanna Sepp 《Fresenius' Journal of Analytical Chemistry》1960,175(6):457
Ohne Zusammenfassung 相似文献
180.
Doaa Abu Saleh Jukka Niskanen Yanming Xue Dmitri Golberg Françoise M. Winnik Alejandro Sosnik 《Materials Today Chemistry》2017
We report an organic-inorganic hybrid core-shell nanomaterial obtained by conjugation of an amphiphilic monomethoxy-poly(ethylene glycol)-b-poly(epsilon-caprolactone) diblock copolymer to hydroxylated boron nitride nanotubes (BNNTs). The extent of copolymer grafting reached 64% w/w, an exceptionally high value. The hybrid materials exhibit excellent physical stability in water and an outstanding loading capacity (31.3% w/w) for curcumin, a hydrophobic drug. Moreover, they present good compatibility with the Caco2 cell line, a model of intestinal epithelium. Our findings demonstrate the potential of multifunctional hybrid BNNTs to serve as a platform for complex amphiphilic nanoparticle architectures with improved features. 相似文献