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1.
Zamfir A Seidler DG Kresse H Peter-Katalinić J 《Rapid communications in mass spectrometry : RCM》2002,16(21):2015-2024
An analytical approach based on high-performance capillary electrophoresis (CE) in conjunction with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) has been developed for providing the basis to obtain new insights into the domain structure of the glycosaminoglycan (GAG) moiety of proteoglycans. The feasibility and performance of the off-line CE/ESI-QTOF-MS approach in GAG oligosaccharide analysis were assessed by screening a chondroitin/dermatan sulfate (DS) oligosaccharide mixture obtained from bovine aorta by enzymatic depolymerization by chondroitin B lyase. The CS/DS mixture was analyzed by CE using 50 mM ammonium acetate, pH 12.0, dissolved in aqueous methanol (2:3; v/v), as a CE carrier. Structural identification of the GAG components was achieved using off-line CE/nanoESI-QTOF-MS and-MS/MS experiments. ESI-QTOF instrumental parameters were found to play an important role in the MS screening of the CE-separated GAG species. By optimizing the ESI conditions, oligosaccharides differing in chain length and degree of sulfation could be detected. The building block composition, the size of the carbohydrate chain, as well as structural features of the repeating HexA-GalNAc, HexA-GalNAc(S) units, have been determined using MS/MS by applying collision-induced dissociation at low energies. Cleavage of GAG chains by chondroitin B lyase occurs with formation of structural markers useful for identification of IdoA-containing domains. 相似文献
2.
Thomas Koch Franz R. Kogler Ulrich Schubert Sabine Seidler 《Monatshefte für Chemie / Chemical Monthly》2007,19(2):293-299
The mechanical properties of hybrid materials consisting of polystyrene (PS), which was cross-linked with different proportions of the multifunctional cluster Zr6O4(OH)4(methacrylate)12 (Zr6) were investigated. With the help of (micro)indentation and scratch testing, the influence of the Zr6 clusters on mechanical properties, such as hardness, stiffness, creep, craze initiation, and scratch resistance was shown.
There was only a slight increase in hardness and in indentation modulus with higher cluster loadings. While this observation
was in agreement with the compression behaviour of the materials, the tensile properties showed a much stronger dependence
on the Zr6 content. With increasing cluster loading, an increase of craze initiation stress, as determined by ball indentation experiments,
was found. Performing scratch testing with constant load, a reduction of pile-up and a stronger recovery were observed for
the hybrid materials compared to the neat PS. Scratch tests with a constant increase of load showed an increase of the critical load for crack opening during scratching. 相似文献
3.
By14C-labeling it is shown that the ring contraction reaction of 1,4-benzothiazin-2,3-4H-dione (1), leading via benzthiazol-2-carbonic acid (2) finally to benzthiazole (3), proceeds via hydrolytic opening of the thiolactone-bond in1, irrespectively of H+ or OH– catalysis. 相似文献
4.
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6.
Samuel Clark Ligon Konstanze Seidler Christian Gorsche Markus Griesser Norbert Moszner Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2016,54(3):394-406
The rapid and uncontrolled nature of network formation from di(meth)acrylate monomers produces high shrinkage stress and results in polymers with oftentimes brittle mechanical properties. Methods for regulating polymerization and network formation are sought. One option is the use of addition–fragmentation chain transfer (AFCT) agents, which are well known to control molecular weight and molecular weight distribution of monofunctional (meth)acrylates. A series of novel and previously described AFCT reagents were synthesized and screened with laser flash photolysis to determine reactivity. Well‐performing AFCT reagents were then tested in polymerizations with monofunctional and difunctional methacrylates. With monofunctional monomers, the molecular weight and polydispersity of the resultant linear polymers tend to decrease with the addition of AFCT agent. In copolymerization with dimethacrylate monomers, the AFCT agents were found to substantially lower and sharpen the glass transition. Sharpness of the glass transition is here indicative of a more regular and homogenous network. After coupling of the instruments, photorheology was performed simultaneously with real‐time IR to show an increase in monomer conversion at the time of gelation, which appears to have a positive effect on reducing shrinkage stress. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 394–406 相似文献
7.
Hermann Seidler 《Fresenius' Journal of Analytical Chemistry》1877,16(1):198-199
Ohne Zusammenfassung 相似文献
8.
Dr. P. Seidler 《Analytical and bioanalytical chemistry》1883,22(1):529-530
9.
Chondroitin/dermatan sulfate (CS/DS) chain of decorin (DCN) from human skin fibroblasts (HSk) was released by reductive β-elimination reaction and digested with chondroitin AC I lyase. Enzymatic hydrolysis mixture of CS/DS chains was separated by size-exclusion chromatography (SEC). Collected octasaccharide fraction was subjected to fully automated chip-based nanoelectrospray (nanoESI) quadrupole time-of-flight (QTOF) MS and tandem MS (MS/MS). MS of human skin fibroblasts DCN CS/DS displayed a high complexity due to the large variety of glycoforms, which under chip-nanoESI MS readily ionized to form multiply charged ions. Except for the regularly tetrasulfated octasaccharide, the investigated fraction contained four additional octasaccharides of atypical sulfation status. Two new oversulfated glycoforms and two undersulfated species were identified. Remarkably, the series of decasaccharides discovered in the same SEC pool was found to encompass a trisulfated and a novel hexasulfated [4,5-Δ-GlcAGalNAc(IdoAGalNAc)?] species. MS/MS by collision-induced dissociation (CID) on the [M-4H]? ion corresponding to the previously not reported [4,5-Δ-GlcAGalNAc(IdoAGalNAc)?](5S) corroborated for a novel motif in which three N-acetylgalactosamine (GalNAc) moieties are monosulfated, 4,5-Δ-GlcA and the first IdoA from the non-reducing end bear one sulfate group each, while the second N-acetylgalactosamine from the reducing end is unsulfated. 相似文献
10.
The calculation of vibrational contributions to molecular properties using vibrational coupled cluster (VCC) response theory is discussed. General expressions are given for expectation values, linear response functions, and transition moments. It is shown how these expressions can be evaluated for arbitrary levels of excitation in the wave function parameterization as well as for arbitrary coupling levels in the potential and property surfaces. The convergence of the method is assessed by benchmark calculations on formaldehyde. Furthermore, excitation energies and infrared intensities are calculated for the fundamental vibrations of furan using VCC limited to up to two-mode and up to three-mode excitations, VCC[2] and VCC[3], as well as VCC with full two-mode and approximate three-mode couplings, VCC[2pt3]. 相似文献