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81.
Precision criteria for multi-component analysis procedures are examined on a statistical basis for calibrating and analytical procedures. The standard deviation σ or its only by measuring approachable estimate s shows to be unsuitable when looked at more closely. By the aid of statistical methods which base on combinatorial rules, and by using redundant calibrating and analytical procedures, the expected value Δ and the second moment of the distribution of the differences of nominal values can be calculated. The expected value Δ E of calibration increases monotonously with the number of over-determinations in calibration samples, while that one for analytical procedures (Δ F ) decreases monotonously, so that there exists a mutual value Δ + for both distributions of differences of nominal values. This is a characteristic magnitude, which only depends on the procedure and the equipment, and it can be applied for the statistical evaluation of calibrating and analytical procedures. The characters $$G_E = \frac{1}{{\Delta ^ + }}{\text{ }}(\Delta ^ + - \Delta _{\rm E} ){\text{ and }}G_F = \frac{1}{{\Delta ^ + }}{\text{ (}}\Delta _F - \Delta ^ + )$$ present themselves as characters of quality for the precision of calibrating and analytical systems. Both characters always are non-negative and decrease monotonously with increasing number of calibration samples. The postulate G E ≤0.2 defines the minimum number of calibration samples, which secures the required compensation of errors as well as an average difference of nominal values for analytical samples Δ F , which is comparable with those for calibration samples. With a great number of calibration samples, however, the second moment is still significantly greater than that one for analytical samples. 相似文献
82.
C. Dedlow D. T. Smith J. Großfeld A. Düring O. Jones E. Waltzinger K. Brauer J. Tillmans R. Strohecker W. Schütze H. Mildner R. Otto Lüttge v. Mertz E. Arbenz R. Herzner O. Mann K. Beck W. Schneider A. Striegel K. Pfizenmaier S. Galanos Th. Sudendorf O. Lahrmann Wilhelm Müller O. Folin L. Geret A. Gompf Gart A. Behre W. Kerp G. Riess A. Juckenack M. Rubner A. Gronover E. Wohnlich H. Willke F. Junker O. Lüning St. Gerö Preußischer Ministerfür Volkswohlfahrt 《Analytical and bioanalytical chemistry》1928,73(1-3):87-104
83.
The unified treatment of the Dirac monopole, the Schwinger monopole, and the Aharonov-Bohm problem by Barut and Wilson is revisited via a path integral approach. The Kustaanheimo-Stiefel transformation of space and time is utilized to calculate the path integral for a charged particle in the singular vector potential. In the process of dimensional reduction, a topological charge quantization rule is derived, which contains Dirac's quantization condition as a special case.
相似文献
84.
85.
Aniline was polymerised enzymatically in aqueous solution at pH = 4.3 and 25°C in the presence of submicrometer-sized vesicles formed from sodium bis(2-ethylhexyl)sulphosuccinate (AOT). H2O2 served as oxidant and the enzyme used was either horseradish peroxidase isoenzyme C (HRPC) or soybean peroxidase (SBP), both being class III peroxidases. From previous studies with HRPC, it is known that stable vesicle suspensions containing the emeraldine salt form of polyaniline (PANI-ES) can be obtained within 1–2 days with a 90–95 % yield, provided that optimal reaction conditions are applied. Unfortunately, HRPC becomes inactivated during polymerisation. In the present study, a linear dendritic block copolymer was added to HRPC, resulting in higher operational enzyme stability; the stabilising effect, however, was too small to afford a substantial decrease in the required amount of enzyme. Moreover, replacing HRPC with SBP was of no advantage, although SBP is known to be more stable towards inactivation by H2O2 than HRPC. By contrast, SBP was found to be much slower in oxidising aniline, and complete inactivation of SBP occurred before all the aniline monomers were oxidised, leading to low yields and the formation of over-oxidised products. The same was observed for HRP isoenzyme A2. Reactions without vesicles indicated that peroxidase inactivation was probably caused by PANI-ES. 相似文献
86.
87.
Hansjoerg Albrecher Corina Constantinescu Enrique Thomann 《Stochastic Processes and their Applications》2012
We consider a renewal jump–diffusion process, more specifically a renewal insurance risk model with investments in a stock whose price is modeled by a geometric Brownian motion. Using Laplace transforms and regular variation theory, we introduce a transparent and unifying analytic method for investigating the asymptotic behavior of ruin probabilities and related quantities, in models with light- or heavy-tailed jumps, whenever the distribution of the time between jumps has rational Laplace transform. 相似文献
88.
Alina Serb Catalin Schiopu Corina Flangea Eugen Sisu Alina D. Zamfir 《Journal of mass spectrometry : JMS》2009,44(10):1434-1442
We developed a straightforward approach for high‐throughput top–down glycolipidomics based on fully automated chip‐nanoelectrospray (nanoESI) high‐capacity ion trap (HCT) multistage mass spectrometry (MSn) by collision‐induced dissociation (CID) in the negative ion mode. The method was optimized and tested on a polysialylated ganglioside fraction (GT1b), which was profiled by MS1 and sequenced in tandem MS up to MS6 in the same experiment. Screening of the fraction in the MS1 mode indicated the occurrence of six [M ? 2H]2? ions which, according to calculation, support 13 GT1 variants differing in their relative molecular mass due to dissimilar ceramide (Cer) constitutions. By stepwise CID MS2–MS5 on the doubly charged ion at m/z 1077.20 corresponding to a ubiquitous GT1b structure, the complete characterization of its oligosaccharide core including the identification of sialylation sites was achieved. Structure of the lipid moiety was further elucidated by CID MS6 analysis carried out using the Y0 fragment ion, detected in MS5, as a precursor. MS6 fragmentation resulted in a pattern supporting a single ceramide form having the less common (d20 : 1/18 : 0) configuration. The entire top–down experiment was performed in a high‐throughput regime in less than 3 min of measurement, with an analysis sensitivity situated in the subpicomolar range. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
89.
Catalin Schiopu Corina Flangea Florina Capitan Alina Serb Željka Vukelić Svjetlana Kalanj-Bognar Eugen Sisu Michael Przybylski Alina D. Zamfir 《Analytical and bioanalytical chemistry》2009,395(8):2465-2477
We report here on a preliminary investigation of ganglioside composition and structure in human hemangioma, a benign tumor
in the frontal cortex (HFC) in comparison to normal frontal cortex (NFC) tissue using for the first time advanced mass spectrometric
methods based on fully automated chip-nanoelectrospray (nanoESI) high-capacity ion trap (HCT) and collision-induced dissociation
(CID). The high ionization efficiency, sensitivity and reproducibility provided by the chip-nanoESI approach allowed for a
reliable MS-based ganglioside comparative assay. Unlike NFC, ganglioside mixture extracted from HFC was found dominated by
species of short glycan chains exhibiting lower overall sialic acid content. In HFC, only GT1 (d18:1/20:0), and GT3 (d18:1/25:1)
polysialylated species were detected. Interestingly, none of these trisialylated forms was detected in NFC, suggesting that
such components might selectively be associated with HFC. Unlike the case of previously investigated high malignancy gliosarcoma,
in HFC one modified O-Ac-GD2 and one modified O-Ac-GM4 gangliosides were observed. This aspect suggests that these O-acetylated structures could be associated with cerebral tumors having reduced malignancy grade. Fragmentation analysis by
CID in MS2 mode using as precursors the ions corresponding to GT1 (d18:1/20:0) and GD1 (d18:1/20:0) provided data corroborating for
the first time the presence of the common GT1a and GT1b isomers and the incidence of unusual GT1c and GT1d glycoforms in brain
hemangioma tumor.
相似文献
90.
The chiral Pt catalyst precursor Pt((R,R)-Me-Duphos)(Ph)(Cl) mediated alkylation of racemic secondary phosphines PHR(R') with benzyl halides in the presence of base to give enantioenriched tertiary phosphines PR(R')(CH2Ar). Similar reactions of bis(secondary) phosphines yielded chiral diphosphines in up to 93% ee and with good rac/meso diastereoselection. 相似文献