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921.
Nasioudis A Heeren RM van Doormalen I de Wijs-Rot N van den Brink OF 《Journal of the American Society for Mass Spectrometry》2011,22(5):837-844
Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming
low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions
of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole
ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid
mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of
substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially
the amine’s degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted
in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information
about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the
ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was
cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium
cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high
molar mass polyethers. 相似文献
922.
We examined the correlation between behavioural reaction time and functional imaging parameters of the blood oxygenated level dependent (BOLD) response in Broca's Area during a word identification task, and whether the correlation [Magnetic Resonance Imaging 22 (2004) 451-455] varies as a function of four stimulus types: regular words (REGs) (e.g., hint), irregular words (IRRs) (e.g., pint), nonwords (NWs) (e.g., bint), and pseudohomophones (PHs) (e.g., pynt). Participants named letter strings aloud during a functional magnetic resonance imaging study. Naming reaction times were recorded during regular gaps in image acquisition, and BOLD parameters were extracted via a Tikhonov regularized BOLD analysis technique. The results revealed that only PH reaction times were correlated with BOLD width, providing evidence that Broca's area supports phonetic decoding accompanied with phonological lexical access. In addition, we advanced the development of equation-based models of cognitive behaviour and neurophysiology, whereby we showed that the relationship of mathematical independence that exists for predicting REG accuracy, given IRR and NW or PH naming accuracy, was present for naming reaction time, BOLD width, BOLD time to peak, and BOLD intensity. Therefore, we provide converging behavioural and neuroanatomical evidence for a mathematically independent relationship between sight vocabulary and phonetic decoding systems, consistent with a dual-route model of reading. 相似文献
923.
Granular cell tumor (GCT) of the larynx is an uncommon, benign laryngeal neoplasm. Abrikossoff first described the tumor in 1926 as myoblastoma. The origin of this tumor has been debated in the literature. Most of the authors believe that the tumor is of neural origin due to the characteristic immunohistochemical-staining pattern. The authors describe two cases of laryngeal GCTs located in different sites with a review of the histological and clinical features, the differential diagnosis, and the treatment and the prognosis of the tumor. 相似文献
924.
925.
Lilian Tichagwa Christian Götz Matthew Tonge Ron Sanderson Harald Pasch 《Macromolecular Symposia》2003,193(1):251-260
Polymerizable surfactants (surfmers) 12-acryloyloxy-dodecanoic acid and 11-acrylamidoundecanoic acid and their respective sodium salts were prepared and then polymerized to form their corresponding oligomers using reversible addition-fragmentation chain transfer (RAFT). Different concentrations of both the surfmers, their sodium salts, and their RAFT oligomers were used as polysoaps in the emulsion polymerization of styrene. Stabilities of the pre-emulsions before polymerization were determined and compared. After polymerization, particle sizes and polydispersities of the resulting polystyrene latices were determined. Sodium dodecyl sulfate (SDS) was used as a reference surfactant to compare the particle sizes and stabilities of the pre-emulsions prepared using surfmers and polymeric surfactants (polysoaps) as particle stabilizers. Emulsion polymerization of styrene using these surfmers and polysoaps all led to latices which were stable for a period of more than six months, as indicated by constant particle sizes, whereas latices prepared using the conventional surfactant, SDS, were not as stable. 相似文献
926.
Marianne E. Prévôt Senay Ustunel Guillaume Freychet Caitlyn R. Webb Mikhail Zhernenkov Ron Pindak Robert J. Clements Elda Hegmann 《Macromolecular bioscience》2023,23(3):2200343
Advanced manufacturing has received considerable attention as a tool for the fabrication of cell scaffolds however, finding ideal biocompatible and biodegradable materials that fit the correct parameters for 3D printing and guide cells to align remain a challenge. Herein, a photocrosslinkable smectic-A (Sm-A) liquid crystal elastomer (LCE) designed for 3D printing is presented, that promotes cell proliferation but most importantly induces cell anisotropy. The LCE-based bio-ink allows the 3D duplication of a highly complex brain structure generated from an animal model. Vascular tissue models are generated from fluorescently stained mouse tissue spatially imaged using confocal microscopy and subsequently processed to create a digital 3D model suitable for printing. The 3D structure is reproduced using a Digital Light Processing (DLP) stereolithography (SLA) desktop 3D printer. Synchrotron Small-Angle X-ray Diffraction (SAXD) data reveal a strong alignment of the LCE layering within the struts of the printed 3D scaffold. The resultant anisotropy of the LCE struts is then shown to direct cell growth. This study offers a simple approach to produce model tissues built within hours that promote cellular alignment. 相似文献