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21.
Mariana Cristea Daniela Gheorghiu Ionita Maria Bruma B. C. Simionescu 《Journal of Thermal Analysis and Calorimetry》2008,93(1):63-68
Two aromatic polyimides and the corresponding poly(amic acid)s, with oxadiazole and para/meta phenoxyphenylene rings in the backbone, were synthesized and the structure — thermal properties correlation was followed
by dynamic mechanical analysis. Concerning the poly(amic acid)s, the glass transition domain was emphasized only for the compound
with meta-oriented rings because the process of imidization takes place with increasing temperature. A multiplex experiment was performed
to calculate the activation energy of the transition localized under 200°C. Consecutive heating-cooling-heating cycles were
accomplished. All phenomena are discussed by cross-examination of the storage modulus (E′), loss modulus (E″) and loss factor tanδ variation with temperature. 相似文献
22.
Iuliu O. Marian Nicolae Bonciocat Cecilia Cristea Robert Săndulescu Monica Bucşa Mircea Vlassa 《Electroanalysis》2010,22(5):542-548
The electrochemical and spectroelectrochemical behavior of 9‐substituted with ? CN and ? COOH acridine N‐oxides with potential antitumor activity was investigated. In SER spectra of the investigated compounds, the ring stretching vibration at 1568 cm?1 for 9‐CN‐substituted compound respectively 1639 cm?1 for 9‐COOH‐substituted compound was analyzed. Cyclic voltammograms indicates that the reduction potential ?0.766 V for ? CN substituted compound increase towards ?0.745 V for ? COOH substituted compound. The proposed theoretical method in the electrochemical impedance spectroscopy uses a reference redox dielectrode and a multielectrode containing the compound. To account for the change of electrochemical impedance we have considered two theoretical quantities: a pseudocapacitance and a pseudo inductance. Two possible arrangements of them: in series, respective in parallel can be used like criteria of drug classification. 相似文献
23.
Electropolymerization of a new phenothiazine derivative (bis-phenothiazin-3-yl methane, BPhM) on glassy carbon electrodes
leads to electroactive and conducting layers of poly-BPhM. Based on the Laviron method, the kinetic parameters (the heterogeneous
electron transfer rate constants k
s and transfer coefficients α) were calculated out of the experimental and theoretical data. The theoretical data have been
obtained by using the analogical modelling and numerical simulating method. The modified electrodes present high values of
k
s(~50s−1) in phosphate buffer solutions of different pH values. A good correlation of mathematical and numerical simulated kinetic
parameters has been obtained, with the experimental values and the norm of residuals being very close to zero. 相似文献
24.
Genovaitė Valiulienė Albina Žielienė Birutė Šimkūnaitė Leonas Naruškevičius Loreta Tamašauskaitė Tamašiūnaitė Vidas Pakštas Algis Selskis 《Journal of Solid State Electrochemistry》2010,14(2):203-212
The electrochemical behavior of Bi2S3 coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal
microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction
in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi2S3 and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S2− ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed
increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni2+ ions reduction before the bulk deposition of Ni, initiated by Bi2S3. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth
sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 1013 to 500–700 Ω cm. A metal-rich mixed sulfide Ni3Bi2S2–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential
close to the equilibrium potential of the Ni/Ni2+ system and then annealed at temperatures higher than 120 °C. 相似文献
25.
Yang Luo Tuo Li Fang Yu Tal Kramer Ileana M. Cristea 《Journal of the American Society for Mass Spectrometry》2010,21(1):34-46
Current biological studies have been advanced by the continuous development of robust, accurate, and sensitive mass spectrometric
technologies. The MALDI LTQ Orbitrap is a new addition to the Orbitrap configurations, known for their high resolving power
and accuracy. This configuration provides features inherent to the MALDI source, such as reduced spectra complexity, forgiveness
to contaminants, and sample retention for follow-up analyses with targeted or hypothesis-driven questions. Here we investigate
its performance for characterizing the composition of isolated protein complexes. To facilitate the assessment, we selected
two well characterized complexes from Saccharomyces cerevisiae, Apl1 and Nup84. Manual and automatic MS and MS/MS analyses readily resolved their compositions, with increased confidence
of protein identification compared with our previous reports using MALDI QqTOF and MALDI IT. CID fragmentation of singly-charged
peptides provided sufficient information for conclusive identification of the isolated proteins. We then assessed the resolution,
accuracy, and sensitivity provided by this instrument in the context of analyzing the isolated protein assemblies. Our analysis
of complex mixtures of singly-charged ions up to m/z 4000 showed that (1) the resolving power, inversely proportional to the square root of m/z, had over four orders of magnitude dynamic range; (2) internal calibration led to improved accuracy, with an average absolute
mass error of 0. 5 ppm and a distribution centered at 0 ppm; and (3) subfemtomole sensitivity was achieved using both CHCA
and DHB matrices. Additionally, our analyses of a synthetic phosphorylated peptide in mixtures showed subfemtomole level of
detection using neutral loss scanning. 相似文献
26.
Ligia Frunza Stefan Frunza Irina Zgura Traian Beica Nicoleta Gheorghe Paul Ganea Daniel Stoenescu Adrian Dinescu Andreas Schönhals 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(4):1228-1235
Composites prepared from aerosil A380 and liquid crystals (LCs) of 4-n-alkyl-4′-cyanophenyl benzoate type, with four to six carbon atoms in the alkyl chain were investigated by infrared spectroscopy. Their high silica content (of 2–7 g aerosil/1 g of LC) was given by thermogravimetric investigations and allows the observation of a rather thin LC layer on the silica particles. Several surface species onto the external surface of the grains were demonstrated. Arguments are given that monomer and dimer species are present in the bulk cyanophenyl benzoate materials while bulk-like species along with hydrogen-bonded ones coexist in the so-called surface layer of the composites. The main interaction of LC molecules with the aerosil surface is by hydrogen bonding taking place with the involvement of the cyan group. There is a contribution of ester carbonyl group to these surface interactions but this cannot be well quantified. 相似文献
27.
28.
Saunoriene Loreta Ragulskis Minvydas Cao Jinde Sanjuán Miguel A. F. 《Nonlinear dynamics》2021,104(1):739-751
Nonlinear Dynamics - The Wada index based on the weighted and truncated Shannon entropy is presented in this paper. The proposed Wada index can detect if a given basin boundary is a Wada boundary.... 相似文献
29.
Mihai Cristea 《Complex Analysis and Operator Theory》2017,11(8):1789-1799
We give a generalization of a known theorem from classical complex analysis, namely the univalence on the boundary theorem. We apply this result to obtain some univalence conditions for Sobolev mappings \(f\in C({\overline{D}},{\mathbb {R}}^n)\bigcap W_{loc}^{1,q}(D,{\mathbb {R}}^n)\) which are injective on \(\partial D\), in connection with a known result of Ball from (Proc R Soc Edinb Sect A 88(3–4):315–328, 1981) modeling nonlinear elasticity. 相似文献
30.
Alexandru C. Razus Liviu Birzan Mihaela Cristea Eugenia Andreea Dragu Anamaria Hanganu 《Monatshefte für Chemie / Chemical Monthly》2011,40(9):1271-1282