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951.
Vincent Caudrelier Aikaterini Gkogkou Barbara Prinari 《Studies in Applied Mathematics》2023,151(1):285-351
The complex coupled short-pulse equation (ccSPE) describes the propagation of ultrashort optical pulses in nonlinear birefringent fibers. The system admits a variety of vector soliton solutions: fundamental solitons, fundamental breathers, composite breathers (generic or nongeneric), as well as so-called self-symmetric composite solitons. In this work, we use the dressing method and the Darboux matrices corresponding to the various types of solitons to investigate soliton interactions in the focusing ccSPE. The study combines refactorization problems on generators of certain rational loop groups, and long-time asymptotics of these generators, as well as the main refactorization theorem for the dressing factors that leads to the Yang–Baxter property for the refactorization map and the vector soliton interactions. Among the results obtained in this paper, we derive explicit formulas for the polarization shift of fundamental solitons that are the analog of the well-known formulas for the interaction of vector solitons in the Manakov system. Our study also reveals that upon interacting with a fundamental breather, a fundamental soliton becomes a fundamental breather and, conversely, that the interaction of two fundamental breathers generically yields two fundamental breathers with a polarization shifts, but may also result into a fundamental soliton and a fundamental breather. Explicit formulas for the coefficients that characterize the fundamental breathers, as well as for their polarization vectors are obtained. The interactions of other types of solitons are also derived and discussed in detail and illustrated with plots. New Yang–Baxter maps are obtained in the process. 相似文献
952.
Kentaro Uesugi Hideyuki Yasuda Barbara Pierscionek Kiyohiko Toyoda Masato Hoshino Naoto Yagi 《Synchrotron Radiation News》2015,28(5):30-35
The medium-length (215 m) bending-magnet beamline 20B2 is allocated to medical applications and various X-ray micro imaging techniques (e.g., angiography, computed tomography, phase contrast imaging and diffraction topography) [1]. The unique properties of BL20B2 are high spatial coherence (large coherent length) and its wide beam cross-section, which come from its long beam transport path and bending magnet light source. The horizontal angular aperture of BL20B2 is 1.5 mrad, as in all bending magnet beamlines at SPring-8. The horizontal beam width at the end station is larger than 300 mm for a 215 m beamline length. 相似文献
953.
954.
Abstract
The crystal structure of the title compound, C4H6N2, has been determined using X-ray diffraction at 100 K. The crystal of 2-methylimidazole is in orthorhombic crystal system with space group P212121 (Z = 4), lattice parameters: a = 5.9957(12) ?, b = 8.1574(16) ? and c = 9.7010(19) ?, V = 474.47(16) ?. The molecule of 2-methylimidazole is approximately planar. The maximum deviation from the least-squares imidazole plane, calculated for all non-H atoms is 0.006(2) ?. N–H···N hydrogen bonds link the molecules together, forming infinite chains of hydrogen bond pattern C(4) defined by the graph-set analysis. Two chains, which are almost antiparallel to each other, pass through each unit cell. The dihedral angle between the mean planes of molecules forming these intersecting chains is 76.90(4)°. No evidence was found for disorder of the hydrogen-bonding proton between the atoms N1 and N3. The significance of this study lies in the analysis of the interactions occurring via hydrogen bonds in this structure, as well as, in the comparison drawn between the molecular structure of 2-methylimidazole and those of several of other imidazole derivatives possessing a hydrogen atom in the N1 position. 相似文献955.
956.
Albertazzi L Storti B Marchetti L Beltram F 《Journal of the American Chemical Society》2010,132(51):18158-18167
Synthesis and targeted delivery of dendrimer-based fluorescent biosensors in living HeLa cells are reported. Following electroporation dendrimers are shown to display specific subcellular localization depending on their size and surface charge and this property is preserved when they are functionalized with sensing moieties. We analyze the case of double dendrimer conjugation with pH-sensitive and pH-insensitive molecules leading to the realization of ratiometric pH sensors that are calibrated in vitro and in living cells. By tuning the physicochemical properties of the dendrimer scaffold sensors can be targeted to specific cellular compartments allowing selective pH measurements in different organelles in living cells. In order to demonstrate the modularity of this approach we present three different pH sensors with tuned H(+) affinity by appropriately choosing the pH-sensitive dye. We argue that the present methodology represents a general approach toward the realization of targetable ratiometric sensors suitable to monitor biologically relevant ions or molecules in living cells. 相似文献
957.
Different RP-HPLC columns (phenyl, conventional ODS, cross-linked C(18) and special end-capped C(8) and C(18) phases) were used to investigate the separation of four basic ionizable isomers. Using ACN/20mM NH(4)OAc aq., a separation was observed exclusively on RP columns with higher silanol activity at unusual high ACN concentration, indicating cation-exchange as main retention mechanism. Using MeOH/20mM NH(4)OAc aq., another separation at low MeOH concentrations was observed on both, RP columns with higher as well as RP columns with lower silanol activity, which is mainly based on hydrophobic interactions. The isomers were also separated on a bare silica column at higher MeOH content using NH(4)OAc. Since cation-exchange governs this retention, the elution order was different compared to the RP phases. A strong retention on the silica column was observed in ACN, which could be attributed to partition processes as additional retention mechanism. 相似文献
958.
Peter Nockemann Dr. Michael Pellens Kristof Van Hecke Dr. Luc Van Meervelt Prof. Dr. Johan Wouters Prof. Dr. Ben Thijs Dr. Evert Vanecht Tatjana N. Parac‐Vogt Prof. Dr. Hasan Mehdi Stijn Schaltin Jan Fransaer Prof. Dr. Stefan Zahn Barbara Kirchner Prof. Dr. Koen Binnemans Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(6):1849-1858
A series of nitrile‐functionalized ionic liquids were found to exhibit temperature‐dependent miscibility (thermomorphism) with the lower alcohols. Their coordinating abilities toward cobalt(II) ions were investigated through the dissolution process of cobalt(II) bis(trifluoromethylsulfonyl)imide and were found to depend on the donor abilities of the nitrile group. The crystal structures of the cobalt(II) solvates [Co(C1C1CNPyr)2(Tf2N)4] and [Co(C1C2CNPyr)6][Tf2N]8, which were isolated from ionic‐liquid solutions, gave an insight into the coordination chemistry of functionalized ionic liquids. Smooth layers of cobalt metal could be obtained by electrodeposition of the cobalt‐containing ionic liquids. 相似文献
959.
Martin Adiels Thomas Larsson Pauline Sutton Marja‐Riitta Taskinen Jan Borén Barbara A. Fielding 《Rapid communications in mass spectrometry : RCM》2010,24(5):586-592
Stable isotope kinetic studies play an important role in the study of very‐low density lipoprotein (VLDL) metabolism, including basic and clinical research. Today, [1,1,2,3,3‐2H5]glycerol is the most cost‐effective alternative to measure glycerol and triglyceride kinetics. Recycling of glycerol from glycolysis and gluconeogenesis may lead to incompletely labelled tracer molecules. Many existing methods for the measurement of glycerol isotopic enrichment involve the production of glycerol derivatives that result in fragmentation of the glycerol molecule after ionization. It would be favourable to measure the intact tracer molecule since incompletely labelled tracer molecules may be measured as fully labelled. The number of methods available to measure the intact tracer in biological samples is limited. The aim of this project was to develop a gas chromatography/mass spectrometry (GC/MS) method for glycerol enrichment that measures the intact glycerol backbone and is suitable for electron ionization (EI), which is widely available. A previously published method for N‐methyl‐N‐[tert‐butyldimethylsilyl]trifluoroacetamide (MTBSTFA) derivatization was significantly improved; we produced a stable derivative and increased recovery 27‐fold in standards. We used the optimized MTBSTFA method in VLDL‐triglyceride and found that further modification was required to take matrix effects into account. We now have a robust method to measure glycerol isotopic enrichment by GC/EI‐MS that can be used to rule out the known problem of tracer recycling in studies of VLDL kinetics. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
960.
Gregorius B Schaumlöffel D Hildebrandt A Tholey A 《Rapid communications in mass spectrometry : RCM》2010,24(22):3279-3289
Metal labelling of peptides and proteins using high-affinity metal-chelating compounds has found widespread applications in the medical and bioanalytical fields. In the present study we investigated the analysis of peptides derivatized either with cysteine- or amino group-directed metal-bound DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) chelators in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The metal complexes of DOTA were shown to be stable under MALDI-MS conditions. The introduction of the metal label led in a number of cases to significantly increased signal-to-noise (S/N) values and thus improved sensitivity of the labelled peptides compared to their unlabelled counterparts, especially for multiply labelled peptides. The presence of the labels did alter the tandem mass spectrometric (MS/MS) behaviour, namely the formation of sequence specific a-, b- and y-ion series, in dependence of the position of the label within the peptide sequence. For cysteine-derivatized peptides several label-specific reporter ions and characteristic immonium ions could be identified. Amino-directed labelling led only to the formation of characteristic immonium ions in ε-amino groups of lysine, whereas N-terminal labelling in some cases led to the formation of a(1)- and b(1)-ions. The results clearly show that MALDI-MS is suitable for the analysis of metal-labelled peptides, which was also confirmed in liquid chromatography (LC)/MALDI-based identification of proteins in a model protein mixture labelled with Cys-reactive DOTA. Here, in comparison to a run with alkylated cysteines, more than 50% more cysteine-containing peptides were identified. 相似文献