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61.
Markus Junker 《Israel Journal of Mathematics》1999,109(1):273-298
Zariski groups are ℵ0-stable groups with an axiomatically given Zariski topology and thus abstract generalizations of algebraic groups. A large
part of algebraic geometry can be developed for Zariski groups. As a main result, any simple smooth Zariski group interprets
an algebraically closed field, hence is almost an algebraic group over an algebraically closed field. 相似文献
62.
Yong P. Chen J. Hitchcock D. Dries M. Junker C. Welford S.E. Pollack T.A. Corcovilos R.G. Hulet 《Physica D: Nonlinear Phenomena》2009,238(15):1321-1325
We review recent studies of the effects of disorder on an atomic Bose-Einstein condensate (BEC). We focus particularly on our own experiments with 7Li BECs in laser speckle. Both the interaction, which gives rise to the nonlinearity in a BEC, and the disorder can be tuned experimentally. This opens many opportunities to study the interplay of interaction and disorder in both condensed matter physics and nonlinear science. 相似文献
63.
Corina Flangea Catalin Schiopu Eugen Sisu Alina Serb Michael Przybylski Daniela G. Seidler Alina D. Zamfir 《Analytical and bioanalytical chemistry》2009,395(8):2489-2498
Chondroitin sulfate (CS) and dermatan sulfate (DS) glycosaminoglycans display variability of sulfation in their constituent
disaccharide repeats during chain elongation. Since a large proportion of the extracellular matrix of the central nervous
system (CNS) is composed of proteoglycans, CS/DS disaccharide degree and profile of sulfation play important roles in the
functional diversity of neurons, brain development, and some of its pathological states. To investigate the sulfation pattern
of CS/DS structures expressed in CNS, we introduced here a novel method based on an advanced system encompassing fully automated
chip nanoelectrospray ionization (nanoESI) in the negative ion mode and high capacity ion trap multistage mass spectrometry
(MS2–MS3) by collision-induced dissociation (CID). This method, introduced here for the first time in glycomics of brain glycosaminoglycans,
was particularly applied to structural investigation of disaccharides obtained by β-elimination and digestion with chondroitin
B and AC I lyase of hybrid CS/DS chains from wild-type mouse brain. Screening in the chip-MS mode of DS disaccharide fraction
resulting after depolymerization with chondroitin B lyase revealed molecular ions assigned to monosulfated disaccharide species
having a composition of 4,5-Δ-[IdoA-GalNAc]. By optimized CID MS2–MS3, fragment ions supporting the localization of sulfate ester group at C4 within GalNAc were produced. Chip ESI MS profiling
of CS disaccharide fraction obtained by depolymerization of the same CS/DS chain using chondroitin AC I lyase indicated the
occurrence of mono- and bisulfated 4,5-Δ-[GlcA-GalNAc]. The site of oversulfation was determined by MS2–MS3, which provided sequence patterns consistent with a rare GlcA-3-sulfate–GalNAc-6-sulfate structural motif.
相似文献
64.
Ioana Sisu Valentina Udrescu Corina Flangea Sorin Tudor Nicolae Dinca Lucian Rusnac Alina D. Zamfir Eugen Sisu 《Central European Journal of Chemistry》2009,7(1):66-73
A variety of carbohydrates, in particular polysaccharides can be subjected to chemical modification to obtain derivatives
with amphiphilic properties, which enable biochemical or biological reactions at the polymer surface. In the present work,
a polydisperse maltodextrin mixture of average molecular weight 3000 was coupled with 1,6-hexamethylenediamine (HMD) via reductive amination reaction. Resulting products were characterized by thermal analysis and positive nanoelectrospray quadrupole
time-of-flight (Q-TOF) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Both thermal analysis and MS screening
confirmed the formation of the HMD-polysaccharide coupling products. Moreover, HMD-linked polysaccharide chains containing
2 to 26 glucose building blocks were identified by nanoESI Q-TOF MS. MS/MS fragmentation using collision-induced dissociation
(CID) at low ion acceleration energies provided strong evidence for HMD-maltodextrin linkage formation and the set of sequence
ions diagnostic for the composition and structure of a HMD-linked chain containing 18 glucose residues.
相似文献
65.
Corina Fetecau Muhammad Jamil Constantin Fetecau Dumitru Vieru 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,25(6):921-933
The velocity field corresponding to the Rayleigh–Stokes problem for an edge, in an incompressible generalized Oldroyd-B fluid
has been established by means of the double Fourier sine and Laplace transforms. The fractional calculus approach is used
in the constitutive relationship of the fluid model. The obtained solution, written in terms of the generalized G-functions, is presented as a sum of the Newtonian solution and the corresponding non-Newtonian contribution. The solution
for generalized Maxwell fluids, as well as those for ordinary Maxwell and Oldroyd-B fluids, performing the same motion, is
obtained as a limiting case of the present solution. This solution can be also specialized to give the similar solution for
generalized second grade fluids. However, for simplicity, a new and simpler exact solution is established for these fluids.
For β → 1, this last solution reduces to a previous solution obtained by a different technique. 相似文献
66.
Dumitru Vieru Corina Fetecau Muhammad Athar Constantin Fetecau 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,60(2):334-343
The unsteady flow of a viscoelastic fluid with the fractional Maxwell model, induced by a constantly accelerating plate between
two side walls perpendicular to the plate, is investigated by means of the integral transforms. Exact solutions for the velocity
field are presented under integral and series forms in terms of the derivatives of generalized Mittag–Leffler functions. The
corresponding solutions for Maxwell fluids are obtained as limiting cases for β → 1. In the absence of the side walls, all
solutions that have been determined reduce to those corresponding to the motion over an infinite plate.
相似文献
67.
The name shape memory originates from the material's capability to recover its original shape after an apparent plastic deformation. The secret of this property lies in the specific microstructure. During mechanical loading, alloys of this particular kind change their crystallographic structure from randomly orientated martensite to ordered martensite. With austenite as high-temperature inter-state induced by heat supply, a recovery from the ordered to the unordered martensite is possible. This is accompanied by a macroscopic "healing" process. We apply our material model for shape-memory alloys to this special property and present numerical results. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
68.
Over the past decades, different software programs have been developed for the Computer-Assisted Structure Elucidation (CASE) with NMR data using with various approaches. WebCocon is one of them that has been continuously improved over the past 20 years. Here, we present the inclusion of CH correlations (-HMBC) in the HMBC interpretation of Cocon and NOE data in WebCocon. The -HMBC data is used during the structure generation process, while the NOE data is used in post-processing of the results. The marine natural product oxocyclostylidol was selected to demonstrate WebCocon’s enhanced HMBC data processing capabilities. A systematic study of the CH correlations of oxocyclostylidol was performed. The application of NOEs in CASE is demonstrated using the NOE correlations of the diterpene pyrone asperginol A known from the literature. As a result, we obtained a conformation that corresponds very well to the existing X-ray structure. 相似文献
69.
Danciu C Soica C Csanyi E Ambrus R Feflea S Peev C Dehelean C 《Chemistry Central journal》2012,6(1):58
ABSTRACT: BACKGROUND: The isoflavonoid genistein represents the major active compound from soybean, the vegetalproduct from Glycine max (Fabaceae). The aim of this study is to prove that genistein wasincorporated in two semisynthetic cyclodextrins, beta-cyclodextrin derivatives:hydroxypropyl-beta-cyclodextrin and randomly-methylated-beta-cyclodextrin as well as to compare the anti-inflammatory activity of genistein with that of genistein incorporated inthese two types of semisynthetic cyclodextrins. RESULTS: The animal studies were conducted on 8-week old C57BL/6 J female mice. Inflammation wasinduced in both ears of each mouse by topical application of 10 micrograms 12-Otetradecanoylphorbol-3-acetate dissolved in 0.1 ml solvent (acetone : dimethylsulfoxide in amolar ratio 9:1). Thirty minutes later treatment was applied. The inflammatory reaction wascorrelated with increased values in ear thickness. Treatment with genistein and genisteinincorporated in the two cyclodextrins led to decreased values for ear thickness. Better antiinflammatoryaction was found for the complexes of genistein. Both haematoxylin-eosinanalysis and CD45 marker expression are in agreement with these findings. CONCLUSIONS: Results allow concluding that genistein is an active anti-inflammatory phytocompound andits complexation with hydrophilic beta-cyclodextrin derivatives leads to a stronger antiinflammatoryactivity. 相似文献
70.
L de Lichtervelde CE Antal AE Boitano Y Wang P Krastel F Petersen AC Newton MP Cooke PG Schultz 《Chemistry & biology》2012,19(8):994-1000
To identify small molecules that selectively control hematopoietic stem cell differentiation, we performed an unbiased screen using primary human CD34(+) cells. We identified a plant-derived natural product, euphohelioscopin A, capable of selectively differentiating CD34(+) cells down the granulocyte/monocytic lineage. Euphohelioscopin A also inhibits proliferation and induces differentiation of the myeloid leukemia cell lines THP-1 and HL-60. Mechanistic studies revealed that euphohelioscopin A is an activator of protein kinase C (PKC), and that the promonocytic effects of this natural product are mediated by PKC activation. In addition to shedding insights into normal hematopoiesis, this work may ultimately facilitate the application of stem cell therapies to a host of myeloid dysfunctions. 相似文献