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181.
The systems Kα of transfinite cumulative types up to α are extended to systems K∞α that include a natural infinitary inference rule, the so‐called limit rule. For countable α a semantic completeness theorem for K∞α is proved by the method of reduction trees, and it is shown that every model of K∞α is equivalent to a cumulative hierarchy of sets. This is used to show that several axiomatic first‐order set theories can be interpreted in K∞α, for suitable α. 相似文献
182.
183.
Siegel M Bethune MT Gass J Ehren J Xia J Johannsen A Stuge TB Gray GM Lee PP Khosla C 《Chemistry & biology》2006,13(6):649-658
Celiac sprue (also known as celiac disease) is an inheritable, gluten-induced enteropathy of the upper small intestine with an estimated prevalence of 0.5%-1% in most parts of the world. The ubiquitous nature of food gluten, coupled with inadequate labeling regulations in most countries, constantly poses a threat of disease exacerbation and relapse for patients. Here, we demonstrate that a two-enzyme cocktail comprised of a glutamine-specific cysteine protease (EP-B2) that functions under gastric conditions and a PEP, which acts in concert with pancreatic proteases under duodenal conditions, is a particularly potent candidate for celiac sprue therapy. At a gluten:EP-B2:PEP weight ratio of 75:3:1, grocery store gluten is fully detoxified within 10 min of simulated duodenal conditions, as judged by chromatographic analysis, biopsy-derived T cell proliferation assays, and a commercial antigluten antibody test. 相似文献
184.
(1) Background: Mass spectrometry-based quantitative proteome profiling is most commonly performed by label-free quantification (LFQ), stable isotopic labeling with amino acids in cell culture (SILAC), and reporter ion-based isobaric labeling methods (TMT and iTRAQ). Isobaric peptide termini labeling (IPTL) was described as an alternative to these methods and is based on crosswise labeling of both peptide termini and MS2 quantification. High quantification accuracy was assumed for IPTL because multiple quantification points are obtained per identified MS2 spectrum. A direct comparison of IPTL with other quantification methods has not been performed yet because IPTL commonly requires digestion with endoproteinase Lys-C. (2) Methods: To enable tryptic digestion of IPTL samples, a novel labeling for IPTL was developed that combines metabolic labeling (Arg-0/Lys-0 and Arg-d4/Lys-d4, respectively) with crosswise N-terminal dimethylation (d4 and d0, respectively). (3) Results: The comparison of IPTL with LFQ revealed significantly more protein identifications for LFQ above homology ion scores but not above identity ion scores. (4) Conclusions: The quantification accuracy was superior for LFQ despite the many quantification points obtained with IPTL. 相似文献
185.
A two-dimensional numerical model is used to study the nonlinear behavior of density gradients on transverse dispersion. Numerical
simulations are conducted using d
3
f, a computer code for simulation of density-dependent flow in porous media. Considering a density-stratified horizontal flow
in a heterogeneous porous media, a series of simulations is carried out to examine the effect of the density gradient on macro-scale
transverse dispersivity. Changing salt concentration significantly affects fluid properties. This physical behavior of the
fluid involves a non-linearity in modeling the interaction between salt and fresh water. It is concluded that the large-scale
transport properties for high density flow deviate significantly from the tracer case due to the spatial variation of permeability,
described by statistical parameters, at the local-scale. Indeed, the presence of vertical flow velocities induced by permeability
variations is responsible for the reduction of the mixing zone width in the steady state in the case of a high density gradient.
Uncertainties in the model simulations are studied in terms of discretization errors, boundary conditions, and convergence
of ensemble averaging. With respect to the results, the gravity number appears to be the controlling parameter for dispersive
flux. In addition, the applicability and limitations of the nonlinear model of Hassanizadeh (1990) and Hassanizadeh and Leijnse
(1995) (Adv Water Resour 18(4):203–215, 1995) in heterogeneous porous media are investigated. We found that the main cause
of the nonlinear behavior of dispersion, which is the interaction between density contrast and vertical velocity, needs to
be explicitly accounted for in a macro-scale model. 相似文献
186.
187.
Transition Metal Chemistry - 相似文献
188.
Jensen JF Svendsen BY la Cour TV Pedersen HL Johannsen M 《Journal of the American Chemical Society》2002,124(17):4558-4559
Currently, the most effective and economic way to convert an alkene into an optically active alcohol is the two-step sequence: hydrosilylation/oxidation. Much work has been devoted to elucidating effective catalysts for this process, but hitherto only one effective and highly stereoselective process has been available. Herein we present a novel catalytic system for the asymmetric hydrosilylation of aromatic alkenes, giving the products in high yields and with the highest enantioselectivity (up to 99% ee) ever observed for this reaction. The reaction works efficiently for a variety of substituted aromatic alkenes, giving access after Tamao oxidation to almost optically pure benzylic alcohols in high yields. 相似文献
189.
O. Johannsen 《Fresenius' Journal of Analytical Chemistry》1911,50(6):385
Ohne Zusammenfassung 相似文献
190.
For the assessment of diets and supplements formulated for the treatment of phenylketonuria, a highly sensitive and selective method was developed and validated for the quantification of dopamine (DA), serotonin (5‐HT), 3,4‐dihydroxyphenylacetic acid (DOPAC), 5‐hydroxyindoleacetic acid (5‐HIAA), phenylalanine, tyrosine and tryptophan in mouse cerebellum, brain stem, hypothalamus, parietal cortex, anterior piriform cortex and bulbus olfactorius. Samples were extracted by deproteinization with acetonitrile, and the extracts were cleaned up by strong anion exchange and weak cation exchange applied sequentially. The substances were detected by rapid liquid chromatography tandem mass spectrometry. Matrix components were largely removed by the clean‐up, resulting in low matrix effects. The lower limits of quantification for an extracted tissue mass of 100 mg were 0.3, 0.3, 0.2 and 2 ng/g for DA, 5‐HT, 5‐HIAA and DOPAC, respectively. The mean true extraction recoveries were 80–102%. The relative intra‐laboratory reproducibility standard deviations were generally <11% at concentrations of 20–1000 ng/g for DA, 5‐HT, 5‐HIAA and DOPAC and 7% at concentrations of 5–50 μg/g for the amino acids. This method was successfully used in a phenylketonuria mice study including nearly 300 brain tissue samples and for small sample masses (for example, 2 mg of bulbus olfactorius). 相似文献