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381.
382.
383.
Constantin Zălinescu 《Optimization and Engineering》2011,12(4):477-487
In this note counter-examples to two triality results are provided. In addition, one of the before mentioned results is corrected
and improved. 相似文献
384.
Beatrice-Cristina Ivan Stefania-Felicia Barbuceanu Camelia Mia Hotnog Adriana Iuliana Anghel Robert Viorel Ancuceanu Mirela Antonela Mihaila Lorelei Irina Brasoveanu Sergiu Shova Constantin Draghici Octavian Tudorel Olaru George Mihai Nitulescu Mihaela Dinu Florea Dumitrascu 《International journal of molecular sciences》2022,23(16)
The current study describes the synthesis, physicochemical characterization and cytotoxicity evaluation of a new series of pyrrole derivatives in order to identify new bioactive molecules. The new pyrroles were obtained by reaction of benzimidazolium bromide derivatives with asymmetrical acetylenes in 1,2-epoxybutane under reflux through the Huisgen [3 + 2] cycloaddition of several ylide intermediates to the corresponding dipolarophiles. The intermediates salts were obtained from corresponding benzimidazole with bromoacetonitrile. The structures of the newly synthesized compounds were confirmed by elemental analysis, spectral techniques (i.e., IR, 1H-NMR and 13C-NMR) and single-crystal X-ray analysis. The cytotoxicity of the synthesized compounds was evaluated on plant cells (i.e., Triticum aestivum L.) and animal cells using aquatic crustaceans (i.e., Artemia franciscana Kellogg and Daphnia magna Straus). The potential antitumor activity of several of the pyrrole derivatives was studied by performing in vitro cytotoxicity assays on human adenocarcinoma-derived cell lines (i.e., LoVo (colon), MCF-7 (breast), and SK-OV-3 (ovary)) and normal human umbilical vein endothelial cells (HUVECs). The obtained results of the cytotoxicity assessment indicated that the tested compounds had nontoxic activity on Triticum aestivum L., while on Artemia franciscana Kellogg nauplii, only compounds 2c and 4c had moderate toxicity. On Daphnia magna, 4b and 4c showed high toxicity; 2a, 2b, and 2c moderate to high toxicity; only 4a and 4d were nontoxic. The compound-mediated cytotoxicity assays showed that several pyrrole compounds demonstrated dose- and time-dependent cytotoxic activity against all tested tumor cell lines, the highest antitumor properties being achieved by 4a and its homologue 4d, especially against LoVo colon cells. 相似文献
385.
Constantin Pyriki 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1925,50(5):366-371
Ohne ZusammenfassungMitteilung aus der Lebensmittelchemischen Abteilung der Staatlichen Landesstelle für öffentliche Gesundheitspflege zu Dresden. (Direktor: Professor Dr. A. Heiduschka). 相似文献
386.
387.
Constantin Claudiu V?duva Nicolae Vaszilcsin Andrea Kellenberger Mihai Medeleanu 《International Journal of Hydrogen Energy》2011,36(12):6994-7001
Benzylamine catalytic effect on the cathodic hydrogen evolution in acid aqueous solution has been studied on copper electrode. Experimental results obtained by voltammetric techniques emphasize that the presence of benzylamine in 1 M sulfuric acid solution enhances the hydrogen evolution reaction (HER). In such a solution, benzylamine is protonated and exists as benzylammonium cation. Kinetic parameters of HER have been determined, observing a significant increase of the exchange current in the presence of benzylamine. Also, a decrease of the cathodic transfer coefficient has been noticed. Activation energy for HER has been computed on the basis of the Arrhenius plots. In the presence of benzylamine the activation energy was 33.0 kJ mol−1, whereas without benzylamine a greater value was obtained: 94.6 kJ mol−1. The catalytic effect of benzylamine was confirmed by electrochemical impedance spectroscopy. The considerable diminution of the double layer capacity is a valid proof of the strong adsorption of benzylamine at the Cu - sulfuric acid solution interface, while the reduction of the charge transfer resistance is a symptom of the enhancement of HER. Ab initio molecular modeling of benzylammonium ion showed that, due to a high value of the dipole moment, the molecules are oriented in the most favorable position for the charge transfer reaction, i.e., with the protonated amino group facing toward the electrode. 相似文献
388.
In the present paper we introduce a new approximation method, called the squared remainder minimization method (SRMM), which allows us to compute analytical approximate polynomial solutions for several nonlinear heat transfer problems. The applications illustrate the validity of the method and a comparison with previous results emphasizes the accuracy of the method. 相似文献
389.
We present a decentralized design that dynamically allocates resources to multiple services inside a global server cluster. The design supports QoS objectives (maximum response time and maximum loss rate) for each service. A system administrator can modify policies that assign relative importance to services and, in this way, control the resource allocation process. Distinctive features of our design are the use of an epidemic protocol to disseminate state and control information, as well as the decentralized evaluation of utility functions to control resource partitioning among services. Simulation results show that the system operates both effectively and efficiently; it meets the QoS objectives and dynamically adapts to load changes and to failures. In case of overload, the service quality degrades gracefully, controlled by the cluster policies. 相似文献
390.
The nitrate complexes of cerium, praseodymium and neodymium with 1,10-phenanthroline(phen) of general formula [Ln(phen)2(NO3)2(H2O)2]·NO3(where, Ln=Ce, Pr and Nd) were prepared and characterized by X-ray crystallography. Thermolysis of these complexes was investigated by simultaneous thermogravimetry(TG) and differential thermal analysis(DTA). Isothermal TG was taken to evaluate the kinetic parameters using model fitting as well as model free isoconversional methods. The thermolytic pathways were also suggested, which involves decomposition followed by ignition. All the three complexes had coordination number ten and showed multistep decompositions. In order to evaluate the response of rapid heating, ignition delay(Di) measurements were undertaken. The activation energies for ignition were found to decrease in the order: NdPrCe. 相似文献