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91.
Cristofor I. Simionescu Virgil BÎrboiu Bogdan C. Simionescu Viorica Talmaciu Corina Sava 《Journal of polymer science. Part A, Polymer chemistry》1986,24(5):851-860
Bulk radical copolymerization of methyl acrylate (MeA, M1) with styrene (St, M2) in presence and absence of ZnCl2 as complexing agent was studied. 1H-NMR spectra were used to establish copolymer composition and sequence distribution. The methoxy group signal was observed to be split due to pentads, but the analysis of sequence distribution is possible only at triad level. Both composition and sequence distribution data confirmed that bulk radical copolymerization respects quite well the terminal addition model; the values of r1 = 0.14 ± 0.02 (from composition data) and r1 = 0.25 ± 0.03 (from sequence distribution data) and r2 = 0.83 ± 0.10 (from composition data) were found. The presence of ZnCl2 increases the probability of alternating addition, e.g., for [ZnCl2]/[MeA] = 0.2, r1 = 0.03 ± 0.02 and r2 = 0.17 ± 0.03. The radical copolymer obtained in bulk in the absence of ZnCl2 presents a coisotactic configuration with σ = 0.75 ± 0.03, but the presence of the complexing agent reduces the probability of coisotactic addition, e.g., for [ZnCl2]/[MeA] = 0.2, σ = 0.52 ± 0.03. 相似文献
92.
D. Vieru Corina Fetecău C. Fetecău 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(5):834-847
The unsteady flow of an Oldroyd-B fluid due to an infinite flat plate, subject to a translation motion of linear time-dependent
velocity in its plane, is studied by means of the Laplace transform. The velocity field and the associated tangential stress
corresponding to the flow induced by the constantly accelerating plate as well as those produced by the impulsive motion of
the plate are obtained as special cases. The solutions that have been determined, in all accordance with the solutions established
using the Fourier transform, reduce to those for a Newtonian fluid as a limiting case. The similar solutions for a Maxwell
fluid are also obtained. 相似文献
93.
Babić-Samardzija K Lupu C Hackerman N Barron AR Luttge A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(26):12187-12196
The heterocyclic diazoles 3-amino-1H-isoindole, indazole, imidazole, 4-bromoimidazole, 4-methylimidazole, pyrazole, 4-nitropyrazole, and 4-sulfopyrazole were investigated as corrosion inhibitors of iron in 1 M HCl using ac and dc techniques. The polarization curves showed a decrease in corrosion current for the inhibitor-containing solution. Impedance spectra demonstrate that the charge-transfer resistance in the presence of these inhibitors was greater than in inhibitor-free solution, except for 4-nitropyrazole. The resistance increased with inhibitor concentration and with immersion time. The structural and electronic parameters of these diazoles were calculated using computational methodologies. The elemental composition and the speciation of the treated surfaces were investigated via XPS measurements, and morphological changes were monitored by vertical scanning interferometery. 相似文献
94.
A novel three-component, one-pot condensation yielding 1H-imidazol-4-yl-pyridines from aldehydes, o-picolylamines, and isocyanides is described. The scope and limitations of the reaction have been investigated. 相似文献
95.
Corina J. van As-Brooks Frans J.M. Hilgers Florien J. Koopmans-van Beinum Louis C.W. Pols 《Journal of voice》2005,19(3):360-372
The purpose of the current study was to assess the anatomic and functional correlates of voice quality in tracheoesophageal speech, with dynamic imaging studies of the neoglottis. Videofluoroscopy (providing a lateral view), digital high-speed endoscopy (providing a "birds-eye" view), and their relationships with perceptual evaluations of voice quality were investigated. Several significant relationships were found. Imaging with videofluoroscopy revealed that the following anatomic and functional parameters (established during phonation) are related to voice quality: presence of a neoglottic bar, regurgitation of barium, tonicity of the neoglottis, and minimal neoglottic distance. Furthermore, the index of the increase of the maximal subneoglottic distance from rest to phonation also showed a significant relationship with voice quality. Imaging with digital high-speed endoscopy revealed features relevant to voice quality, including amount of saliva, visibility of the origin of the neoglottis, shape of the neoglottis, and regularity of the vibration. Knowledge of the anatomic and functional correlates of tracheoesophageal voice quality provides prerequisite information for future (phono-) surgical and/or clinical improvements to the voice quality of postlaryngectomy (prosthetic) voice production. 相似文献
96.
Dr. Stefan Henkel Corina H. Pollok Tim Schleif Prof. Dr. Wolfram Sander 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12479-12486
Four isomeric azulenylcarbenes were synthesized in argon matrices by photolysis of the corresponding diazo precursors, and the photochemistry of these carbenes was studied. The carbenes and their rearranged products were characterized by IR, UV/Vis, and EPR spectroscopy, and the experimental data were compared to results from DFT calculations. While 2‐, 5‐ and 6‐azulenylcarbene show triplet ground states, 1‐azulenylcarbene exhibits a singlet ground state, in accord with theoretical predictions. The rearrangements of the azulenylcarbenes give access to a number of unusual C11H8 isomers, such as other carbenes and strained allenes. 相似文献
97.
Calin Vasile Andritoiu Corina Elena Andriescu Constanta Ibanescu Cristina Lungu Bianca Ivanescu Laurian Vlase Cornel Havarneanu Marcel Popa 《Molecules (Basel, Switzerland)》2020,25(22)
The present paper aims to formulate and characterize four phytotherapeutic ointments based on Hippophae fructus, Calendulae flos, Bardanae folium, and Millefolii herba, which are included in a novel ointment base. In order to investigate the healing properties of the ointments, in vivo experimental wound models of linear incision, circular excision, and thermal burn were performed on Wistar rats. Topical treatment was performed daily for 21 days. Determination of the wound contraction rate (WCR), the period of reepithelization, and histopathological examination were achieved. Additionally, for the tested ointments, oscillatory and rotational rheological tests were carried out, and for the extracts, HPLC analysis was performed. The results demonstrate that the tested novel ointments are safe for use and the most effective ointment proved to be the one based on Arctium lappa, followed by that of Calendulae flos. 相似文献
98.
Corina Aramă Camelia Nicolescu Angela Nedelcu Crina-Maria Monciu 《Journal of inclusion phenomena and macrocyclic chemistry》2011,70(3-4):421-428
An inclusion complex between repaglinide and a cyclodextrin derivative, 7-sulfobutylether-β-cyclodextrin (Captisol®) was synthesized and characterized taking into account its possible benefits regarding the solubility, thus the bioavailability of repaglinide (an oral antidiabetic, carbamoyl methyl benzoic acid, practically insoluble in water, used for the treatment of type II diabetes mellitus). In order to establish the optimal conditions for the synthesis, phase-solubility studies were performed. Their results (AL type phase-solubility diagram), as well as the chromatographic retention behavior of repaglinide in the presence of Captisol® indicated that an 1:1 inclusion complex is formed. The estimated apparent stability constant, according to the Higuchi-Connors method is 530 M?1. These data were confirmed by 1H-NMR, IR, DTA of the inclusion complex prepared through lyophilization. 相似文献
99.
M. Nazar Corina Fetecau D. Vieru C. Fetecau 《Nonlinear Analysis: Real World Applications》2010,11(1):584-591
New exact solutions for the velocity field corresponding to the second problem of Stokes, for second grade fluids, have been established by the Laplace transform method. These solutions, presented as a sum of the steady-state and transient solutions, are in accordance with the previous solutions obtained by a different technique. The required time to reach the steady state is determined by graphical illustrations. This time decreases if the frequency of the velocity increases. The effects of the material parameters on the decay of the transients are also investigated by graphs. 相似文献
100.
Corina Flangea Alina F. Serb Catalin Schiopu Sorin Tudor Eugen Sisu Daniela G. Seidler Alina D. Zamfir 《Central European Journal of Chemistry》2009,7(4):752-759
Sulfation pattern within chondroitin sulfate (CS) glycosaminoglycan (GAG) chains is an important post-translational modification
that regulates their interaction with proteins. In this context, development of highly efficient and reproducible analytical
methods for the investigation of CS sulfation patterns is of high necessity. In this study we report a novel method for straightforward
determination of N-acetylgalactosamine (GalNAc) sulfation sites in chondroitin sulfate disaccharides. Our protocol involves
combining fully automated chip-based nanoelectrospray (nanoESI) for analyte infusion and ionization in negative ion mode with
multistage (MSn) collision-induced dissociation (CID) high capacity ion trap (HCT) mass spectrometry for generation of sequence ions diagnostic
for identification of sulfate ester group position within GalNAc residues. The feasibility of this approach is here demonstrated
on chondroitin 6-O-sulfate and chondroitin 4-O-sulfate disaccharides. Fragmentation patterns obtained by MS2 and MS3 sequencing stages provided first mass spectrometric data from which sulfation site(s) within GalNAc monosaccharide ring could
be unequivocally deciphered. Hence, the method allowed discriminating 4S/6S sulfation sites solely on the basis of MS and
multistage MS evidence.
相似文献