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101.
Corina Cheptea Valeriu Sunel Jacques Desbrieres Marcel Popa 《Journal of heterocyclic chemistry》2013,50(2):366-372
The synthesis of new derivatives of 1,3,4‐thiadiazoles and 1,2,4‐triazoles was achieved using the 1,4‐disubstituted thiosemicarbazides as intermediaries. 相似文献
102.
Alina D. Zamfir Dragana Fabris Florina Capitan Cristian Munteanu Željka Vukelić Corina Flangea 《Analytical and bioanalytical chemistry》2013,405(23):7321-7335
In this preliminary investigation, a low-grade astrocytoma (AcT) is investigated by high-resolution (HR) mass spectrometry (MS) aiming at characterization of gangliosides with potential biomarker value. The research was conducted towards a comparative mapping of ganglioside expression in AcT, its surrounding tissue (ST) and a normal control brain tissue (NT). HR MS was conducted in the negative ion mode nanoelectrospray ionization (nanoESI). Fragmentation analysis was carried out by collision-induced dissociation (CID) MS2–MS4. Due to the high resolving power and mass accuracy, by comparative mapping of the ganglioside extracts from AcT, ST and NT, under identical conditions, 37 different species in AcT, 40 in ST and 56 in NT were identified. AcT and ST were found to contain 18 identical ganglioside components. Among all three specimens, ST extract presented the highest levels of sialylation, fucosylation and acetylation, a feature which might be correlated to the tumor expansion in the adjacent brain area. MS mapping indicated also that AcT, ST and NT share one doubly deprotonated molecule at m/z 1063.31, attributable to GT1(d18:1/18:0) or GT1(d18:0/18:1). CID MS2–MS4 on these particular ions detected in AcT and ST provided data supporting GT1c isomer in the investigated astrocytoma tissue. Our results show that HR MS has a remarkable potential in brain cancer research for the determination of tumor-associated markers and for their structural determination. Figure
Ganglioside isomer discrimination in human astrocytoma by Orbitrap multistage MS 相似文献
103.
Corina Flangea Catalin Schiopu Florina Capitan Cristina Mosoarca Marilena Manea Eugen Sisu Alina D. Zamfir 《Central European Journal of Chemistry》2013,11(1):25-34
The conventional protocol for protein identification by electrospray ionization mass spectrometry (MS) is based on enzymatic digestion which renders peptides to be analyzed by liquid chromatography-MS and collision-induced dissociation (CID) multistage MS, in the so-called bottom-up approach. Though this method has brought a significant progress to the field, many limitations, among which, the low throughput and impossibility to characterize in detail posttranslational modifications in terms of site(s) and structure, were reported. Therefore, the research is presently focused on the development of procedures for efficient top-down fragmentation of intact protein ions. In this context, we developed here an approach combining fully automated chip-based-nanoelectrospray ionisation (nanoESI), performed on a NanoMate robot, with electron transfer dissociation (ETD) for peptide and top-down protein sequencing and identification. This advanced analytical platform, integrating robotics, microfluidics technology, ETD and alternate ETD/CID, was tested and found ideally suitable for structural investigation of peptides and modified/functionalized peptides as well as for top-down analysis of medium size proteins by tandem MS experiments of significantly increased throughput and sensitivity. The obtained results indicate that NanoMate-ETD and ETD/CID may represent a viable alternative to the current MS strategies, with potential to develop into a method of routine use for high throughput top-down proteomics. 相似文献
104.
Stefania Racovita Nicolae Baranov Ana Maria Macsim Catalina Lionte Corina Cheptea Valeriu Sunel Marcel Popa Silvia Vasiliu Jacques Desbrieres 《Molecules (Basel, Switzerland)》2020,25(22)
New grafted copolymers possessing structural units of 1-vinyl-3-(1-carboxymethyl) imidazolium betaine were obtained by graft copolymerization of N-vinylimidazole onto gellan gum followed by the polymer-analogous reactions on grafted polymer with the highest grafting percentage using sodium chloroacetate as the betainization agent. The grafted copolymers were prepared using ammonium persulfate/N,N,N′,N′ tetramethylethylenediamine in a nitrogen atmosphere. The grafting reaction conditions were optimized by changing one of the following reaction parameters: initiator concentration, monomer concentration, polymer concentration, reaction time or temperature, while the other parameters remained constant. The highest grafting yield was obtained under the following reaction conditions: ci = 0.08 mol/L, cm = 0.8 mol/L, cp = 8 g/L, tr = 4 h and T = 50 °C. The kinetics of the graft copolymerization of N-vinylimidazole onto gellan was discussed and a suitable reaction mechanism was proposed. The evidence of the grafting reaction was confirmed through FTIR spectroscopy, X-ray diffraction, 1H-NMR spectroscopy and scanning electron microscopy. The grafted copolymer with betaine structure was obtained by a nucleophilic substitution reaction where the betainization agent was sodium chloroacetate. Preliminary results prove the ability of the grafted copolymers to bind amphoteric drugs (cefotaxime) and, therefore, the possibility of developing the new sustained drug release systems. 相似文献
105.
Daria L. Melnikova Zilya F. Badrieva Mikhail A. Kostin Corina Maller Monika Stas Aneta Buczek Malgorzata A. Broda Teobald Kupka Anne-Marie Kelterer Peter M. Tolstoy Vladimir D. Skirda 《Molecules (Basel, Switzerland)》2020,25(23)
In this work, the nuclear magnetic resonance (NMR) and IR spectroscopic markers of the complexation between 5-fluorouracil (5-FU) and β-cyclodextrin (β-CD) in solid state and in aqueous solution are investigated. In the attenuated total reflectance(ATR) spectra of 5-FU/β-CD products obtained by physical mixing, kneading and co-precipitation, we have identified the two most promising marker bands that could be used to detect complex formations: the C=O and C-F stretching bands of 5-FU that experience a blue shift by ca. 8 and 2 cm−1 upon complexation. The aqueous solutions were studied by NMR spectroscopy. As routine NMR spectra did not show any signs of complexation, we have analyzed the diffusion attenuation of spin–echo signals and the dependence of the population factor of slowly diffusing components on the diffusion time (diffusion NMR of pulsed-field gradient (PFG) NMR). The analysis has revealed that, at each moment, ~60% of 5-FU molecules form a complex with β-CD and its lifetime is ca. 13.5 ms. It is likely to be an inclusion complex, judging from the independence of the diffusion coefficient of β-CD on complexation. The obtained results could be important for future attempts of finding better methods of targeted anticancer drug delivery. 相似文献
106.
107.
Constantin Fetecau Corina Fetecau 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2005,16(1):1098-1106
The velocity fields corresponding to some flows of second grade and Maxwell fluids, induced by a circular cylinder subject
to a constantly accelerating translation along its symmetry axis, are presented as Fourier-Bessel series in terms of the eigenfunctions
of some suitable boundary value problems. These solutions satisfy both the associate partial differential equations and all
imposed initial and boundary conditions. For α or λ → 0, they are going to those for a Newtonian fluid. Finally, for comparison,
some diagrams corresponding to the solutions for the flow through a circular cylinder are presented for different values of
t and of the material constants. 相似文献
108.
Corina J. van As Frans J.M. Hilgers Irma M. Verdonck-de Leeuw Florien J. Koopmans-van Beinum 《Journal of voice》1998,12(2):239-248
Voice analysis was performed on 21 “standard” laryngectomized, male patients with a Provox® voice prosthesis, along with an age- and sex-matched control group of 20 normal speakers, using acoustical analyses (MDVP and CSL, Kay Elemetrics Corp.), maximum phonation time measurements, and perceptual evaluations. Comparison between MDVP and CSL revealed that the latter was not useful for the analysis of laryngectomized prosthetic voices. In contrast, MDVP seems suitable for this purpose, and contains a large number of parameters that significantly differentiate between patient and control speakers, as did the perceptual ratings and the maximum phonation time. Fundamental frequency appeared to be comparable for patients and control speakers. A significant influence of stoma occlusion and age was found for some voice parameters. Factor analyses showed correlations between the different MDVP parameters and correlations between the MDVP parameters and the perceptual ratings. 相似文献
109.
Zamfir AD Serb A Vukeli Ž Flangea C Schiopu C Fabris D Kalanj-Bognar S Capitan F Sisu E 《Journal of the American Society for Mass Spectrometry》2011,22(12):2145-2159
Gangliosides (GGs), sialic acid-containing glycosphingolipids, are known to be involved in the invasive/metastatic behavior
of brain tumor cells. Development of modern methods for determination of the variations in GG expression and structure during
neoplastic cell transformation is a priority in the field of biomedical analysis. In this context, we report here on the first
optimization and application of chip-based nanoelectrospray (NanoMate robot) mass spectrometry (MS) for the investigation
of gangliosides in a secondary brain tumor. In our work a native GG mixture extracted and purified from brain metastasis of
lung adenocarcinoma was screened by NanoMate robot coupled to a quadrupole time-of-flight MS. A native GG mixture from an
age-matched healthy brain tissue, sampled and analyzed under identical conditions, served as a control. Comparative MS analysis
demonstrated an evident dissimilarity in GG expression in the two tissue types. Brain metastasis is characterized by many
species having a reduced N-acetylneuraminic acid (Neu5Ac) content, however, modified by fucosylation or O-acetylation such as Fuc-GM4, Fuc-GM3, di-O-Ac-GM1, O-Ac-GM3. In contrast, healthy brain tissue is dominated by longer structures exhibiting from mono- to hexasialylated sugar
chains. Also, significant differences in ceramide composition were discovered. By tandem MS using collision-induced dissociation
at low energies, brain metastasis-associated GD3 (d18:1/18:0) species as well as an uncommon Fuc-GM1 (d18:1/18:0) detected
in the normal brain tissue could be structurally characterized. The novel protocol was able to provide a reliable compositional
and structural characterization with high analysis pace and at a sensitivity situated in the fmol range. 相似文献
110.
Corina Constantinescu Enkelejd Hashorva Lanpeng Ji 《Insurance: Mathematics and Economics》2011,49(3):487-495
In this paper we discuss the link between Archimedean copulas and L1 Dirichlet distributions for both finite and infinite dimensions. With motivation from the recent papers Weng et al. (2009) and Albrecher et al. (2011) we apply our results to certain ruin problems. 相似文献