The stereospecific synthesis of aryloxy and amino substituted E- and Z-ethyl-3-acrylates is of interest because of their potential in the polymer industry and in medicinal chemistry. During work on a copper-catalyzed cross-coupling reaction of ethyl (E)- and (Z)-3-iodoacrylates with phenols and N-heterocycles, we discovered a very simple (nonmetallic) method for the stereospecific synthesis of aryloxy and amino substituted acrylates. To study this long-standing problem on the stereoselectivity of aryloxy and amino substituted acrylates, a series of O- and N-substituted nucleophiles was allowed to react with ethyl (E)- and (Z)-3-iodoacrylates. Screening of different bases indicated that DABCO (1,4-diazabicyclo[2.2.2]octane) afforded successful conversion of ethyl (E)- and (Z)-3-iodoacrylates into aryloxy and amino substituted ethyl acrylates in a stereospecific manner. Herein are the details of this DABCO-mediated stereospecific synthesis of aryloxy and amino substituted E- or Z-acrylates. 相似文献
Patient-specific sequential epitopes were identified by peptide chip analysis using 15mer peptides immobilized on glass slides
that covered the topoisomerase IIa protein with a frameshift of five amino acids. Binding specificities of serum antibodies
against sequential epitopes were confirmed as being mono-specific by peptide chip re-analysis of epitope-affinity-purified
antibody pools. These results demonstrate that serum samples from colon carcinoma patients contain antibodies against sequential
epitopes from the topoisomerase IIa antigen. Interactions of patients’ antibodies with sequential epitopes displayed by peptides
on glass surfaces may thus mirror disease-specific immune situations. Consequently, these data suggest epitope–antibody reactivities
on peptide chips as potential diagnostic readouts of individual immune response characteristics, especially because monospecific
antibodies can be interrogated. Subsequently, the clonality of the antibodies present in the mono-specific antibody pools
was characterized by 2D gel electrophoresis. This analysis suggested that the affinity-purified antibodies were oligoclonal.
Similarly to large-scale screening approaches for specific antigen–antibody interactions in order to improve disease diagnostic,
we suggest that “protein-wide” screening for specific epitope–paratope interactions may help to develop novel assays for monitoring
of personalized therapies, since individual properties of antigen–antibody interactions remain distinguishable. 相似文献
The synthesis, spectroscopic characterization and crystal structures of the first 1,4-bis(4-nitrosophenyl)piperazine (BNPP) (4) bridged dinuclear complexes of rhodium(III) and iridium(III) are presented. The reaction of the μ(2)-halogenido-bridged dimers [(η(5)-C(5)Me(5))IrX(2)](2) [X = Cl (5a), Br (5b), I (5c)] and [(η(5)- C(5)Me(5))RhCl(2)](2) (6a) with 4 yields the dinuclear complexes [(η(5)-C(5)Me(5))IrX(2)](2)-BNPP (7a-c) and [(η(5)-C(5)Me(5))RhCl(2)](2)-BNPP (8a). All new compounds were characterized by their NMR, IR and mass spectra. The X-ray structure analyses of the obtained half-sandwich complexes revealed a slightly distorted pseudo-octahedral configuration ("three-legged pianostool") for the metal(III) centers. The bridging BNPP ligand is σ-N coordinated by both nitroso groups and shows different conformations of the piperazine ring depending on the solvent used for crystallization. Moreover the crystal structures of 1,4-bis(4-nitrosophenyl)piperazine (4) and its precursor 1,4-diphenylpiperazine (3) are reported. 相似文献
In this paper, we prove a local in time unique existence theorem for the free boundary problem of a compressible barotropic viscous fluid flow without surface tension in the \(L_p\) in time and \(L_q\) in space framework with \(2 < p < \infty \) and \(N < q < \infty \) under the assumption that the initial domain is a uniform \(W^{2-1/q}_q\) one in \({\mathbb {R}}^{N}\, (N \ge 2\)). After transforming a unknown time dependent domain to the initial domain by the Lagrangian transformation, we solve problem by the Banach contraction mapping principle based on the maximal \(L_p\)–\(L_q\) regularity of the generalized Stokes operator for the compressible viscous fluid flow with free boundary condition. The key issue for the linear theorem is the existence of \({\mathcal {R}}\)-bounded solution operator in a sector, which combined with Weis’s operator valued Fourier multiplier theorem implies the generation of analytic semigroup and the maximal \(L_p\)–\(L_q\) regularity theorem. The nonlinear problem we studied here was already investigated by several authors (Denisova and Solonnikov, St. Petersburg Math J 14:1–22, 2003; J Math Sci 115:2753–2765, 2003; Secchi, Commun PDE 1:185–204, 1990; Math Method Appl Sci 13:391–404, 1990; Secchi and Valli, J Reine Angew Math 341:1–31, 1983; Solonnikov and Tani, Constantin carathéodory: an international tribute, vols 1, 2, pp 1270–1303, World Scientific Publishing, Teaneck, 1991; Lecture notes in mathematics, vol 1530, Springer, Berlin, 1992; Tani, J Math Kyoto Univ 21:839–859, 1981; Zajaczkowski, SIAM J Math Anal 25:1–84, 1994) in the \(L_2\) framework and Hölder spaces, but our approach is different from them. 相似文献
The combination of the Passerini reaction and olefin cross‐metathesis is shown to be a very useful approach for the divergent synthesis of dendrimers. Castor oil‐derived platform chemicals, such as 10‐undecenoic acid and 10‐undecenal, are reacted in a Passerini reaction with an unsaturated isocyanide to obtain a core unit having three terminal double bonds. Subsequent olefin cross‐metathesis with tert‐butyl acrylate, followed by hydrogenation of the double bonds and hydrolysis of the tert‐butyl ester, leads to an active core unit bearing three carboxylic acid groups as reactive sites. Iterative steps of the Passerini reaction with 10‐undecenal and 10‐isocyanodec‐1‐ene for branching, and olefin cross‐metathesis with tert‐butyl acrylate, followed by hydrogenation and hydrolysis allow the synthesis of a third‐generation dendrimer. All steps of the synthesis are carefully characterized by NMR, GPC, MS, and IR.
Abstract Since the end of the 80s elemental analyzer-isotope ratio mass spectrometer connections have been used for the fast, automatic and highly precise determination of carbon and nitrogen content as well as their isotopic composition in one run. But for artificially enriched stable isotopes as tracer in biological processes and since these processes have a high biological variability anyway (e.g. soil processes) the use of these highly precise but also sophisticated and expensive instruments is not required. In this case the use of a quadrupole mass spectrometer connected with an elemental analyzer can offer a low cost alternative. As shown, such coupling is suitable for automatic simultaneous routine analysis of total nitrogen and carbon and their isotopic enrichment (15N, 13C) in plant material and soils. The relative standard deviation for 15N and 13C determination is 2% To meet this precision a careful sample homogenization by grinding is very important. The duration of one measurement is 6–8 min. depending on whether nitrogen alone or both nitrogen and carbon are determined. This enables a high sample throughput. 相似文献
Abstract One of the main problems while developing analytical multilayer models for ion implantation is how to make them ‘physical'. Satisfactory agreement between results obtained with existing multilayer models and the Monte Carlo prediction cannot always be expected, since mostly none of the important physical effects is accounted for. Extensive Monte Carlo study has been performed in order to extract some guiding principles for the construction of a more physically based multilayer model. Ion reflection accross the interfaces has a very strong impact on the final shape of a multilayer profile. First attempts to include this phenomenon in a multilayer model have been made. In this paper, a simple approach for light ion reflection at an interface is presented and the incorporation into a multilayer model is discussed. 相似文献
The nanostructuring of dielectrics is a big challenge for laser patterning methods. In this study a novel laser structuring method for the fabrication of randomly distributed nanostructures, called laser-induced front side etching using in situ pre-structured metal layers (IPSM-LIFE), is presented. The pulsed laser irradiation of a thin metal film deposited onto a dielectric substrate with fluences below the ablation threshold results in the formation of randomly distributed metal structures by self-assembly processes. Further pulsed laser irradiation of these metal structures with higher or equal laser fluences causes the formation of complex patterns at the surface of the dielectric due to localized ablation and melting processes of the dielectric surface induced by the absorption of the laser energy by the metal structures and the local energy transfer into the dielectric surface. The pattern formation observed in the film and the dielectrics substrate after irradiation of 10 nm chromium layers on fused silica, with laser pulses (Δtp=25 ns, λ=248 nm), was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different features with a lateral size down to a few tens of nanometers, like concentric ring patterns, donut-like structures, and bar patterns were observed at the dielectric. 相似文献
A new secondary isotopic reference material has been prepared from Puerto Rico precipitation, which was filtered, homogenised, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and calibrated by dual-inlet isotope-ratio mass spectrometry. This isotopic reference material, designated as USGS48, is intended to be one of two isotopic reference waters for daily normalisation of stable hydrogen (δ2H) and stable oxygen (δ18O) isotopic analysis of water with a mass spectrometer or a laser absorption spectrometer. The δ2H and δ18O values of this reference water are?2.0±0.4 and?2.224±0.012 ‰, respectively, relative to Vienna Standard Mean Ocean Water on scales normalised such that the δ2H and δ18O values of Standard Light Antarctic Precipitation reference water are?428 and?55.5 ‰, respectively. Each uncertainty is an estimated expanded uncertainty (U=2uc) about the reference value that provides an interval that has about a 95 % probability of encompassing the true value. This isotopic reference water is available by the case of 144 glass ampoules containing 5 mL of water in each ampoule. 相似文献
In an attempt to combine non-commutative geometry and quantum gravity, Aastrup-Grimstrup-Nest construct a semi-finite spectral triple, modeling the space of G-connections for G = U(1) or SU (2). AGN show that the interaction between the algebra of holonomy loops ${\mathcal{B}}$ and the Dirac type operator ${\mathcal{D}}$ quantizes the Poisson structure of General Relativity in Ashtekar’s loop variables. This article generalizes AGN’s construction to any connected compact Lie group G. A construction of AGN’s semi-finite spectral triple in terms of an inductive limit of spectral triples is formulated. The refined construction permits the semi-finite spectral triple to be even when G is even dimensional. The Dirac-type operator ${\mathcal{D}}$ in AGN’s semi-finite spectral triple is a weighted sum of a basic Dirac operator on G. The weight assignment is a diverging sequence that governs the “volume” associated to each copy of G. The JLO cocycle of AGN’s triple is examined in terms of the weight assignment. An explicit condition on the weight assignment perturbations is given, so that the associated JLO class remains invariant. Such a condition leads to a functoriality property of AGN’s construction. 相似文献