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71.
Hugo M. Ortner Gerhard Schlemmer Bernhard Welz W. Wegscheider 《Spectrochimica Acta Part B: Atomic Spectroscopy》1985,40(7):959-977
Morphological studies on graphite tube surfaces by scanning electron microscopy are presented for unused and corroded tubes from various endurance experiments in electrothermal AAS.Tubes always break in their center as this is the hottest part; tube thinning occurs predominantly at the outside. The inner surface of tubes coated with pyrographite is usually only slightly corroded, unless highly aggressive reagents are applied. Deposition of carbon in thin layers as well as in nodules is observed in the hot central zone. 相似文献
72.
Online LC-MS-MS process monitoring for optimization of biological treatment of wastewater containing azo dye concentrates 总被引:1,自引:0,他引:1
A biological high-performance treatment process comprising two 40-L reactor compartments has been developed for purification
and decoloration of concentrated textile wastewater containing up to 15 g L−1 reactive dyestuff. The decoloration rate of 95% meets the requirements of German legislation for textile wastewater treatment.
Successful process development and optimization was achieved by use of high-performance liquid chromatography, with diode-array
and electrospray tandem mass spectrometric (LC-ESI-MS-MS) detection, coupled with inline microfiltration membrane-sampling
devices, applied online to bioreactors as a process analytical tool for the first time. The optimum process performance was
found by correlation of dye and decoloration product-specific concentrations with summary properties such as redox potential
and dissolved oxygen content. Details of the degradation and decoloration mechanism for the azo dye reactive black 5 was revealed
by using mass spectrometry for structure elucidation. 相似文献
73.
Loison JC Bergeat A Caralp F Hannachi Y 《The journal of physical chemistry. A》2006,110(50):13500-13506
The reactions of the CH radical with several alkanes were studied, at room temperature, in a low-pressure fast-flow reactor. CH(X2Pi, v = 0) radicals were obtained from the reaction of CHBr(3) with potassium atoms. The overall rate constants at 300 K are (0.76 +/- 0.20) x 10(-10) [Fleurat-Lessard, P.; Rayez, J. C.; Bergeat, A.; Loison, J. C. Chem. Phys. 2002, 279, 87],1 (1.60 +/- 0.60) x 10(-10)[Galland, N.; Caralp, F.; Hannachi, Y.; Bergeat, A.; Loison, J.-C. J. Phys. Chem. A 2003, 107, 5419],2 (2.20 +/- 0.80) x 10(-10), (2.80 +/- 0.80) x 10(-10), (3.20 +/- 0.80) x 10(-10), (3.30 +/- 0.60) x 10(-10), and (3.60 +/- 0.80) x 10(-10) cm3 molecule(-1) s(-1), (errors refer to +/-2sigma) for methane, ethane, propane, n-butane, n-pentane, neo-pentane, and n-hexane respectively. The experimental overall rate constants correspond to those obtained using a simple classical capture theory. Absolute atomic hydrogen production was determined by V.U.V. resonance fluorescence, with H production from the CH + CH4 reaction being used as a reference. Observed H branching ratios were for CH4, 1.00[Fleurat-Lessard, P.; Rayez, J. C.; Bergeat, A.; Loison, J. C. Chem. Phys. 2002, 279, 87];1 C(2)H(6), 0.22 +/- 0.08 [Galland, N.; Caralp, F.; Hannachi, Y.; Bergeat, A.; Loison, J.-C. J. Phys. Chem. A 2003, 107, 5419];2 C(3)H(8), 0.19 +/- 0.07; C(4)H(10) (n-butane), 0.14 +/- 0.06; C(5)H(12) (n-pentane), 0.52 +/- 0.08; C(5)H(12) (neo-pentane), 0.51 +/- 0.08; C(5)H(12) (iso-pentane), 0.12 +/- 0.06; C(6)H(14) (n-hexane), 0.06 +/- 0.04. 相似文献
74.
Norbert Ortner 《Monatshefte für Mathematik》2010,160(3):313-335
We investigate several conditions of the convolvability and ${\mathcal{S}'}$ -convolvability of distributions and we show their equivalence by characterizing the partial summability of distribution kernels by multiplicative properties. More generally, partial summability to the power p and the partial vanishing at infinity of kernels are characterized by multiplicative properties. As an application we state several sufficient equivalent conditions ensuring the validity of the equation, $$ (\partial_jS)\ast T=S\ast (\partial_j T).$$ Furthermore, it is shown that the Chevalley condition for the convolvability of two distributions ${S,T\in\mathcal{D}'}$ , i.e., $$ (\varphi\ast S)(\psi\ast\check T)\in L^1\quad\text{for all }\varphi,\psi\in\mathcal D,$$ is equivalent with $$S(x-y)T(y-z)\in\mathcal D'_{xz}\hat\otimes L^1_y.$$ 相似文献
75.
The 1,4-addition of the lithium enolate of methyldithioacetate (LMDTA) to (+/-)-4-O-TBS-2-cyclohexenone (3) can be varied from being highly 3,4-trans selective to being highly 3,4-cis selective simply by varying the reaction temperature. This stereodivergency allows expedient syntheses of the corresponding trans and cis methyl esters 6t and 6c and derived bicyclic ketolactones 7t and 7c. 相似文献
76.
77.
Daniel Leitner Sabine Klepsch Astrid Knieß Andrea Schnepf 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(6):575-587
Understanding the impact of root architecture on plant resource efficiency is important, in particular, in the light of upcoming shortages of mineral fertilizers and changed environmental conditions. In the 1950s, a great number of root systems of European cultivated plants were excavated and studied by L. Kutschera (1960). Her work gave enormous insight into the variety of root system architectures and helped to realize the importance of belowground processes to plant productivity. We analysed the resulting hand drawings by using mathematical modelling and found root system parameters for a newly developed parametric L-System model. In this way we were able to first reproduce the illustrations, second computationally analyse root system traits and finally access the dynamic root architecture development. 相似文献
78.
79.
The lateral Casimir-Polder force between an atom and a corrugated surface should allow one to study experimentally nontrivial geometrical effects in the electromagnetic quantum vacuum. Here, we derive the theoretical expression of this force in the scattering approach. We show that large corrections to the "proximity force approximation" could be measured using present-day technology with a Bose-Einstein condensate used as a vacuum field sensor. 相似文献
80.
Kornelija Lasi Ana Bokuli Astrid Mili Biljana Nigovi Ana Mornar 《Biomedical chromatography : BMC》2019,33(8)
This paper presents lipophilicity and bio‐mimetic property determination of 15 phytoestrogens, namely biochanin A, daidzein, formononetin, genistein, genistein‐4,7‐dimethylether, prunetin, 3,4,7‐trihydroxyisoflavon, 4,6,7‐trihydroxyisoflavon, 4,6,7‐trimethoxyisoflavon, daidzin, genistin, ononin, sissotrin, coumestrol and coumestrol dimethylether. High‐performance liquid chromatography with fast gradient elution and Caco‐2 cell line were used to determine the physicochemical properties of selected phytoestrogens. Lipophilicity was determined on octadecyl‐sylane stationary phase using pH 2.0 and pH 7.4 buffers. Immobilized artificial membrane chromatography was used for prediction of interaction with biological membranes. Protein binding was measured on human serum albumin and α‐1‐acid‐glycoprotein (AGP) stationary phases. Caco‐2 assay was used as a gold standard for assessing in vitro permeability. The obtained results differentiate phytoestrogens according to their structure where aglycones show significantly higher lipophilicity, immobilized artificial membrane partitioning, AGP binding and Caco‐2 permeability compared with glucosides. However, human serum albumin binding was very high for all investigated compounds. Furthermore, a good correlation between experimentally obtained chromatographic parameters and in silico prediction was obtained for lipophilicity and human serum albumin binding, while the somewhat greater difference was obtained for AGP binding and Caco‐2 permeability. 相似文献